64 results on '"Wilhelmsson U"'
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2. Retinoids and activation of PKC induce tissue‐type plasminogen activator expression and storage in human astrocytes
- Author
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HULTMAN, K., TJÄRNLUND‐WOLF, A., FISH, R.J., WILHELMSSON, U., RYDENHAG, B., PEKNY, M., KRUITHOF, E.K.O., and JERN, C.
- Published
- 2008
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3. Short general anaesthesia induces prolonged changes in gene expression in the mouse hippocampus
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PEKNY, T., ANDERSSON, D., WILHELMSSON, U., PEKNA, M., and PEKNY, M.
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- 2014
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4. GFAP AND VIMENTIN ARE NEGATIVE REGULATORS OF THE HIPPOCAMPAL NEUROGENIC NICHE: W08-04
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Pekny, M., Widestrand, Å., Wilhelmsson, U., Andersson, D., Linde, S., Smith, P. L., Christianson, H., Slaba, B., Pekny, T., Pekna, M., and Faiz, M.
- Published
- 2009
5. Appendix
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Alves, Valter, Cunningham, S, Droumeva, M, Grimshaw, M, Hug, D, Liljedahl, M, O'Keeffe, L, and Wilhelmsson, U
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Sound Design ,ComputingMilieux_PERSONALCOMPUTING ,Videogames - Abstract
What will the player experience of computer game sound be in the future? This was the question posed in an online discussion forum to which the book’s contributors were invited to respond. What follows is a free-wheeling debate about the future of game sound. Little editing has been done, other than the most obvious grammar, syntax and spelling errors, in order to maintain the fresh, often off-the-cuff responses. Three related themes become apparent in this discussion: affect, emotion and biofeedback; realism versus alternative realities; and the need for a game-sound design aesthetics. The first opens up interesting possibilities for enhanced player interaction (including player-player interaction across networked games) and immersion. Although authors and games companies often talk about the player being immersed in the gameworld, it is clear that current technology only hints at the potential. Similarly, games companies often praise the realism of their game sounds: even the iconic sound of Atari’s Pong of the early 1970s had its synthetic tones described as “realistic”. But which realism is being alluded to? What precisely does this Holy Grail of realism represent and how should it be attained? Is it the authenticity of sound that contributes to game realism or its verisimilitude in the context? If the latter, does realism derive from expectation, culture and genre and what debt does it owe to other forms of media? If realism refers to an emulation of reality, do we mean social realism, thematic realism, consequential or physical realism and who wants to play reality anyway? These questions directly relate to the need for a game sound design language: something that is still nascent. Game sound involves a very different paradigm to the derivation and perception of sound as found in reality or any other form of recreational medium. Like real-world environments, game sound derives from the actions of and upon its entities but it is triggered from a different rather than issuing directly from those entities. Unlike cinema, games require the willing and active participation of the player to effect the game and its sound. Whatever the future holds, it is clear that we have only begun to discover the possibilities inherent in computer game sound.
- Published
- 2011
6. GFAP and Astrocyte Intermediate Filaments
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Pekny, M., primary and Wilhelmsson, U., additional
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7. 333 Rat hepatic stellate cells express the intermediate filament anchor protein synemin
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Uyama, N., primary, Zhao, L., additional, Eliasson, C., additional, Wilhelmsson, U., additional, Reynaert, H., additional, Adams, D.H., additional, Pinzani, M., additional, Titeux, M., additional, Li, Z.L., additional, Robson, R., additional, Pekny, M., additional, and Geerts, A., additional
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- 2004
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8. Short general anaesthesia induces prolonged changes in gene expression in the mouse hippocampus
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Pekny T, Andersson D, Wilhelmsson U, Marcela Pekna, and Pekny M
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Male ,Mice ,Time Factors ,Ethanol ,Isoflurane ,Anesthetics, Inhalation ,Animals ,Gene Expression ,Anesthesia, General ,Real-Time Polymerase Chain Reaction ,Hippocampus - Abstract
The long-term molecular changes in the central nervous system constitute an important aspect of general anaesthesia, but little is known about to what extent these molecular changes are affected by anaesthesia duration. The aim of the present study was to evaluate the effects of short duration (20 min) general anaesthesia with isoflurane or avertin on the expression of 20 selected genes in the mouse hippocampus at 1 and 4 days after anaesthesia.Nine to eleven-weeks-old male mice received one of the following treatments: 20 min of avertin-induced anaesthesia (n=11), 20 min of isoflurane-induced anaesthesia (n=10) and no anaesthesia (n=5). One and four days after anaesthesia, gene expression in the hippocampus was determined with reverse transcription quantitative real-time polymerase chain reaction.We found that anaesthesia led to the upregulation of six genes: Hspd1 (heat shock protein 1), Plat (tissue plasminogen activator) and Npr3 (natriuretic peptide receptor 3) were upregulated only 1 day after anaesthesia, whereas Thbs4 (thrombospondin 4) was upregulated only 4 days after anaesthesia. Syp (synaptophysin) and Mgst1 (microsomal glutathione S-transferase 1) were upregulated at both time points. Hspd1, Mgst1 and Syp expression was increased regardless of the anaesthetic used, Npr3 and Plat were increased only in mice exposed to avertin, and Thbs4 was upregulated only after isoflurane-induced anaesthesia.This study shows that some of the effects of short general anaesthesia on gene expression in the mouse hippocampus persist for at least 4 days.
9. Reactive astrocytes prevent maladaptive plasticity after ischemic stroke.
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Aswendt M, Wilhelmsson U, Wieters F, Stokowska A, Schmitt FJ, Pallast N, de Pablo Y, Mohammed L, Hoehn M, Pekna M, and Pekny M
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- Animals, Astrocytes metabolism, Gliosis metabolism, Humans, Mice, Neuronal Plasticity, Recovery of Function physiology, Ischemic Stroke, Stroke
- Abstract
Restoration of functional connectivity is a major contributor to functional recovery after stroke. We investigated the role of reactive astrocytes in functional connectivity and recovery after photothrombotic stroke in mice with attenuated reactive gliosis (GFAP
-/- Vim-/- ). Infarct volume and longitudinal functional connectivity changes were determined by in vivo T2-weighted magnetic resonance imaging (MRI) and resting-state functional MRI. Sensorimotor function was assessed with behavioral tests, and glial and neural plasticity responses were quantified in the peri-infarct region. Four weeks after stroke, GFAP-/- Vim-/- mice showed impaired recovery of sensorimotor function and aberrant restoration of global neuronal connectivity. These mice also exhibited maladaptive plasticity responses, shown by higher number of lost and newly formed functional connections between primary and secondary targets of cortical stroke regions and increased peri-infarct expression of the axonal plasticity marker Gap43. We conclude that reactive astrocytes modulate recovery-promoting plasticity responses after ischemic stroke., (Copyright © 2021. Published by Elsevier Ltd.)- Published
- 2022
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10. Diet-induced weight loss in obese/diabetic mice normalizes glucose metabolism and promotes functional recovery after stroke.
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Karampatsi D, Zabala A, Wilhelmsson U, Dekens D, Vercalsteren E, Larsson M, Nyström T, Pekny M, Patrone C, and Darsalia V
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- Animals, Behavior, Animal, Biomarkers blood, Brain metabolism, Brain pathology, Diabetes Mellitus, Type 2 blood, Diabetes Mellitus, Type 2 physiopathology, Diet, High-Fat, Disease Models, Animal, Glycemic Control, Infarction, Middle Cerebral Artery blood, Infarction, Middle Cerebral Artery pathology, Infarction, Middle Cerebral Artery physiopathology, Male, Mice, Inbred C57BL, Obesity blood, Obesity physiopathology, Recovery of Function, Stroke blood, Stroke pathology, Stroke physiopathology, Time Factors, Mice, Blood Glucose metabolism, Brain physiopathology, Diabetes Mellitus, Type 2 diet therapy, Infarction, Middle Cerebral Artery diet therapy, Obesity diet therapy, Stroke diet therapy, Weight Loss
- Abstract
Background: Post-stroke functional recovery is severely impaired by type 2 diabetes (T2D). This is an important clinical problem since T2D is one of the most common diseases. Because weight loss-based strategies have been shown to decrease stroke risk in people with T2D, we aimed to investigate whether diet-induced weight loss can also improve post-stroke functional recovery and identify some of the underlying mechanisms., Methods: T2D/obesity was induced by 6 months of high-fat diet (HFD). Weight loss was achieved by a short- or long-term dietary change, replacing HFD with standard diet for 2 or 4 months, respectively. Stroke was induced by middle cerebral artery occlusion and post-stroke recovery was assessed by sensorimotor tests. Mechanisms involved in neurovascular damage in the post-stroke recovery phase, i.e. neuroinflammation, impaired angiogenesis and cellular atrophy of GABAergic parvalbumin (PV)+ interneurons were assessed by immunohistochemistry/quantitative microscopy., Results: Both short- and long-term dietary change led to similar weight loss. However, only the latter enhanced functional recovery after stroke. This effect was associated with pre-stroke normalization of fasting glucose and insulin resistance, and with the reduction of T2D-induced cellular atrophy of PV+ interneurons. Moreover, stroke recovery was associated with decreased T2D-induced neuroinflammation and reduced astrocyte reactivity in the contralateral striatum., Conclusion: The global diabetes epidemic will dramatically increase the number of people in need of post-stroke treatment and care. Our results suggest that diet-induced weight loss leading to pre-stroke normalization of glucose metabolism has great potential to reduce the sequelae of stroke in the diabetic population., (© 2021. The Author(s).)
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- 2021
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11. Neurofilament Light Chain (NfL) in Blood-A Biomarker Predicting Unfavourable Outcome in the Acute Phase and Improvement in the Late Phase after Stroke.
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Pekny M, Wilhelmsson U, Stokowska A, Tatlisumak T, Jood K, and Pekna M
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- Animals, Axons pathology, Humans, Magnetic Resonance Imaging methods, Neurodegenerative Diseases blood, Neurodegenerative Diseases pathology, Prognosis, Biomarkers blood, Neurofilament Proteins blood, Stroke blood, Stroke pathology
- Abstract
Increased sensitivity of methods assessing the levels of neurofilament light chain (NfL), a neuron-specific intermediate filament protein, in human plasma or serum, has in recent years led to a number of studies addressing the utility of monitoring NfL in the blood of stroke patients. In this review, we discuss that elevated blood NfL levels after stroke may reflect several different neurobiological processes. In the acute and post-acute phase after stroke, high blood levels of NfL are associated with poor clinical outcome, and later on, the blood levels of NfL positively correlate with secondary neurodegeneration as assessed by MRI. Interestingly, increased blood levels of NfL in individuals who survived stroke for more than 10 months were shown to predict functional improvement in the late phase after stroke. Whereas in the acute phase after stroke the injured axons are assumed to be the main source of blood NfL, synaptic turnover and secondary neurodegeneration could be major contributors to blood NfL levels in the late phase after stroke. Elevated blood NfL levels after stroke should therefore be interpreted with caution. More studies addressing the clinical utility of blood NfL assessment in stroke patients are needed before the inclusion of NfL in the clinical workout as a useful biomarker in both the acute and the chronic phase after stroke.
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- 2021
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12. Nestin affects fusion pore dynamics in mouse astrocytes.
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Lasič E, Trkov Bobnar S, Wilhelmsson U, de Pablo Y, Pekny M, Zorec R, and Stenovec M
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- Animals, Biological Transport, Cell Fusion, Cells, Cultured, Exocytosis physiology, Mice, Mice, Inbred C57BL, Mice, Knockout, Nestin genetics, Signal Transduction, Adenosine Triphosphate metabolism, Astrocytes metabolism, Calcium metabolism, Cell Membrane metabolism, Nestin metabolism
- Abstract
Aim: Astrocytes play a homeostatic role in the central nervous system and influence numerous aspects of neurophysiology via intracellular trafficking of vesicles. Intermediate filaments (IFs), also known as nanofilaments, regulate a number of cellular processes including organelle trafficking and adult hippocampal neurogenesis. We have recently demonstrated that the IF protein nestin, a marker of neural stem cells and immature and reactive astrocytes, is also expressed in some astrocytes in the unchallenged hippocampus and regulates neurogenesis through Notch signalling from astrocytes to neural stem cells, possibly via altered trafficking of vesicles containing the Notch ligand Jagged-1., Methods: We thus investigated whether nestin affects vesicle dynamics in astrocytes by examining single vesicle interactions with the plasmalemma and vesicle trafficking with high-resolution cell-attached membrane capacitance measurements and confocal microscopy. We used cell cultures of astrocytes from nestin-deficient (Nes
-/- ) and wild-type (wt) mice, and fluorescent dextran and Fluo-2 to examine vesicle mobility and intracellular Ca2+ concentration respectively., Results: Nes-/- astrocytes exhibited altered sizes of vesicles undergoing full fission and transient fusion, altered vesicle fusion pore geometry and kinetics, decreased spontaneous vesicle mobility and altered ATP-evoked mobility. Purinergic stimulation evoked Ca2+ signalling that was slightly attenuated in Nes-/- astrocytes, which exhibited more oscillatory Ca2+ responses than wt astrocytes., Conclusion: These results demonstrate at the single vesicle level that nestin regulates vesicle interactions with the plasmalemma and vesicle trafficking, indicating its potential role in astrocyte vesicle-based communication., (© 2019 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.)- Published
- 2020
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13. Nestin Null Mice Show Improved Reversal Place Learning.
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Wilhelmsson U, Kalm M, Pekna M, and Pekny M
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- Animals, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Exploratory Behavior physiology, Memory physiology, Motor Activity physiology, Nestin deficiency, Reversal Learning physiology
- Abstract
The intermediate filament protein nestin is expressed by neural stem cells, but also by some astrocytes in the neurogenic niche of the hippocampus in the adult rodent brain. We recently reported that nestin-deficient (Nes
-/- ) mice showed increased adult hippocampal neurogenesis, reduced Notch signaling from Nes-/- astrocytes to the neural stem cells, and impaired long-term memory. Here we assessed learning and memory of Nes-/- mice in a home cage set up using the IntelliCage system, in which the mice learn in which cage corner a nose poke earns access to drinking water. Nes-/- and wildtype mice showed comparable place learning assessed as the incorrect corner visit ratio and the incorrect nose poke ratio. However, during reversal place learning, a more challenging task, Nes-/- mice, compared to wildtype mice, showed improved learning over time demonstrated by the incorrect visit ratio and improved memory extinction over time assessed as nose pokes per visit to the previous drinking corner. In addition, Nes-/- mice showed increased explorative activity as judged by the increased total numbers of corner visits and nose pokes. We conclude that Nes-/- mice exhibit improved reversal place learning and memory extinction, a finding which together with the previous results supports the concept of the dual role of hippocampal neurogenesis in cognitive functions.- Published
- 2020
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14. Nestin Regulates Neurogenesis in Mice Through Notch Signaling From Astrocytes to Neural Stem Cells.
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Wilhelmsson U, Lebkuechner I, Leke R, Marasek P, Yang X, Antfolk D, Chen M, Mohseni P, Lasič E, Bobnar ST, Stenovec M, Zorec R, Nagy A, Sahlgren C, Pekna M, and Pekny M
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- Animals, Astrocytes cytology, Cell Differentiation, Cell Proliferation, Coculture Techniques, Jagged-1 Protein metabolism, Male, Memory, Long-Term physiology, Mice, Inbred C57BL, Mice, Knockout, Nestin genetics, Rats, Signal Transduction, Astrocytes metabolism, Brain metabolism, Nestin metabolism, Neural Stem Cells metabolism, Neurogenesis, Receptors, Notch metabolism
- Abstract
The intermediate filament (nanofilament) protein nestin is a marker of neural stem cells, but its role in neurogenesis, including adult neurogenesis, remains unclear. Here, we investigated the role of nestin in neurogenesis in adult nestin-deficient (Nes-/-) mice. We found that the proliferation of Nes-/- neural stem cells was not altered, but neurogenesis in the hippocampal dentate gyrus of Nes-/- mice was increased. Surprisingly, the proneurogenic effect of nestin deficiency was mediated by its function in the astrocyte niche. Through its role in Notch signaling from astrocytes to neural stem cells, nestin negatively regulates neuronal differentiation and survival; however, its expression in neural stem cells is not required for normal neurogenesis. In behavioral studies, nestin deficiency in mice did not affect associative learning but was associated with impaired long-term memory., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2019
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15. Vimentin Phosphorylation Is Required for Normal Cell Division of Immature Astrocytes.
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de Pablo Y, Marasek P, Pozo-Rodrigálvarez A, Wilhelmsson U, Inagaki M, Pekna M, and Pekny M
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- Animals, Astrocytes cytology, Astrocytes physiology, Cells, Cultured, Glial Fibrillary Acidic Protein genetics, Glial Fibrillary Acidic Protein metabolism, Mice, Mice, Inbred C57BL, Mutation, Phosphorylation, Protein Domains, Vimentin chemistry, Vimentin genetics, Astrocytes metabolism, Cell Division, Neurogenesis, Vimentin metabolism
- Abstract
Vimentin (VIM) is an intermediate filament (nanofilament) protein expressed in multiple cell types, including astrocytes. Mice with VIM mutations of serine sites phosphorylated during mitosis (VIM
SA/SA ) show cytokinetic failure in fibroblasts and lens epithelial cells, chromosomal instability, facilitated cell senescence, and increased neuronal differentiation of neural progenitor cells. Here we report that in vitro immature VIMSA/SA astrocytes exhibit cytokinetic failure and contain vimentin accumulations that co-localize with mitochondria. This phenotype is transient and disappears with VIMSA/SA astrocyte maturation and expression of glial fibrillary acidic protein (GFAP); it is also alleviated by the inhibition of cell proliferation. To test the hypothesis that GFAP compensates for the effect of VIMSA/SA in astrocytes, we crossed the VIMSA/SA and GFAP-/- mice. Surprisingly, the fraction of VIMSA/SA immature astrocytes with abundant vimentin accumulations was reduced when on GFAP-/- background. This indicates that the disappearance of vimentin accumulations and cytokinetic failure in mature astrocyte cultures are independent of GFAP expression. Both VIMSA/SA and VIMSA/SA GFAP-/- astrocytes showed normal mitochondrial membrane potential and vulnerability to H2 O2 , oxygen/glucose deprivation, and chemical ischemia. Thus, mutation of mitotic phosphorylation sites in vimentin triggers formation of vimentin accumulations and cytokinetic failure in immature astrocytes without altering their vulnerability to oxidative stress., Competing Interests: The authors declare no conflict of interest.- Published
- 2019
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16. Vimentin is required for normal accumulation of body fat.
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Wilhelmsson U, Stillemark-Billton P, Borén J, and Pekny M
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- Absorptiometry, Photon, Animal Feed, Animals, Body Weight, Female, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Vimentin genetics, Adipose Tissue diagnostic imaging, Vimentin physiology
- Abstract
Intermediate filaments (nanofilaments) have many functions, especially in response to cellular stress. Mice lacking vimentin (Vim-/-) display phenotypes reflecting reduced levels of cell activation and ability to counteract stress, for example, decreased reactivity of astrocytes after neurotrauma, decreased migration of astrocytes and fibroblasts, attenuated inflammation and fibrosis in lung injury, delayed wound healing, impaired vascular adaptation to nephrectomy, impaired transendothelial migration of lymphocytes and attenuated atherosclerosis. To address the role of vimentin in fat accumulation, we assessed the body weight and fat by dual-energy X-ray absorptiometry (DEXA) in Vim-/- and matched wildtype (WT) mice. While the weight of 1.5-month-old Vim-/- and WT mice was comparable, Vim-/- mice showed decreased body weight at 3.5, 5.5 and 8.5 months (males by 19-22%, females by 18-29%). At 8.5 months, Vim-/- males and females had less body fat compared to WT mice (a decrease by 24%, p < 0.05, and 33%, p < 0.0001, respectively). The body mass index in 8.5 months old Vim-/- mice was lower in males (6.8 vs. 7.8, p < 0.005) and females (6.0 vs. 7.7, p < 0.0001) despite the slightly lower body length of Vim-/- mice. Increased mortality was observed in adult Vim-/- males. We conclude that vimentin is required for the normal accumulation of body fat.
- Published
- 2019
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17. The role of GFAP and vimentin in learning and memory.
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Wilhelmsson U, Pozo-Rodrigalvarez A, Kalm M, de Pablo Y, Widestrand Å, Pekna M, and Pekny M
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- Animals, Glial Fibrillary Acidic Protein genetics, Hippocampus physiology, Intermediate Filaments metabolism, Male, Maze Learning, Mice, Mice, Knockout, Neurogenesis, Vimentin genetics, Glial Fibrillary Acidic Protein physiology, Learning physiology, Memory physiology, Vimentin physiology
- Abstract
Intermediate filaments (also termed nanofilaments) are involved in many cellular functions and play important roles in cellular responses to stress. The upregulation of glial fibrillary acidic protein (GFAP) and vimentin (Vim), intermediate filament proteins of astrocytes, is the hallmark of astrocyte activation and reactive gliosis in response to injury, ischemia or neurodegeneration. Reactive gliosis is essential for the protective role of astrocytes at acute stages of neurotrauma or ischemic stroke. However, GFAP and Vim were also linked to neural plasticity and regenerative responses in healthy and injured brain. Mice deficient for GFAP and vimentin (GFAP-/-Vim-/-) exhibit increased post-traumatic synaptic plasticity and increased basal and post-traumatic hippocampal neurogenesis. Here we assessed the locomotor and exploratory behavior of GFAP-/-Vim-/- mice, their learning, memory and memory extinction, by using the open field, object recognition and Morris water maze tests, trace fear conditioning, and by recording reversal learning in IntelliCages. While the locomotion, exploratory behavior and learning of GFAP-/-Vim-/- mice, as assessed by object recognition, the Morris water maze, and trace fear conditioning tests, were comparable to wildtype mice, GFAP-/-Vim-/- mice showed more pronounced memory extinction when tested in IntelliCages, a finding compatible with the scenario of an increased rate of reorganization of the hippocampal circuitry.
- Published
- 2019
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18. Astrocyte activation and reactive gliosis-A new target in stroke?
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Pekny M, Wilhelmsson U, Tatlisumak T, and Pekna M
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- Animals, Astrocytes metabolism, Gliosis metabolism, Humans, Astrocytes pathology, Gliosis pathology, Stroke pathology, Stroke therapy
- Abstract
Stroke is an acute insult to the central nervous system (CNS) that triggers a sequence of responses in the acute, subacute as well as later stages, with prominent involvement of astrocytes. Astrocyte activation and reactive gliosis in the acute stage of stroke limit the tissue damage and contribute to the restoration of homeostasis. Astrocytes also control many aspects of neural plasticity that is the basis for functional recovery. Here, we discuss the concept of intermediate filaments (nanofilaments) and the complement system as two handles on the astrocyte responses to injury that both present attractive opportunities for novel treatment strategies modulating astrocyte functions and reactive gliosis., (Copyright © 2018. Published by Elsevier B.V.)
- Published
- 2019
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19. Vimentin deficiency in macrophages induces increased oxidative stress and vascular inflammation but attenuates atherosclerosis in mice.
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Håversen L, Sundelin JP, Mardinoglu A, Rutberg M, Ståhlman M, Wilhelmsson U, Hultén LM, Pekny M, Fogelstrand P, Bentzon JF, Levin M, and Borén J
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- Animals, CD36 Antigens metabolism, Lipoproteins, LDL metabolism, Macrophages immunology, Mice, Mice, Transgenic, Vimentin metabolism, Atherosclerosis metabolism, Macrophages metabolism, Oxidative Stress, Vasculitis metabolism, Vimentin genetics
- Abstract
The aim was to clarify the role of vimentin, an intermediate filament protein abundantly expressed in activated macrophages and foam cells, in macrophages during atherogenesis. Global gene expression, lipid uptake, ROS, and inflammation were analyzed in bone-marrow derived macrophages from vimentin-deficient (Vim
-/- ) and wild-type (Vim+/+ ) mice. Atherosclerosis was induced in Ldlr-/- mice transplanted with Vim-/- and Vim+/+ bone marrow, and in Vim-/- and Vim+/+ mice injected with a PCSK9 gain-of-function virus. The mice were fed an atherogenic diet for 12-15 weeks. We observed impaired uptake of native LDL but increased uptake of oxLDL in Vim-/- macrophages. FACS analysis revealed increased surface expression of the scavenger receptor CD36 on Vim-/- macrophages. Vim-/- macrophages also displayed increased markers of oxidative stress, activity of the transcription factor NF-κB, secretion of proinflammatory cytokines and GLUT1-mediated glucose uptake. Vim-/- mice displayed decreased atherogenesis despite increased vascular inflammation and increased CD36 expression on macrophages in two mouse models of atherosclerosis. We demonstrate that vimentin has a strong suppressive effect on oxidative stress and that Vim-/- mice display increased vascular inflammation with increased CD36 expression on macrophages despite decreased subendothelial lipid accumulation. Thus, vimentin has a key role in regulating inflammation in macrophages during atherogenesis.- Published
- 2018
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20. Increased Neuronal Differentiation of Neural Progenitor Cells Derived from Phosphovimentin-Deficient Mice.
- Author
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Chen M, Puschmann TB, Marasek P, Inagaki M, Pekna M, Wilhelmsson U, and Pekny M
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- Animals, Astrocytes cytology, Astrocytes metabolism, Cell Proliferation, Cell Survival, Dentate Gyrus cytology, Intermediate Filaments metabolism, Mice, Inbred C57BL, Neurogenesis, Phosphorylation, Spheroids, Cellular cytology, Wound Healing, Cell Differentiation, Neural Stem Cells cytology, Neurons cytology, Vimentin deficiency, Vimentin metabolism
- Abstract
Vimentin is an intermediate filament (also known as nanofilament) protein expressed in several cell types of the central nervous system, including astrocytes and neural stem/progenitor cells. Mutation of the vimentin serine sites that are phosphorylated during mitosis (VIM
SA/SA ) leads to cytokinetic failures in fibroblasts and lens epithelial cells, resulting in chromosomal instability and increased expression of cell senescence markers. In this study, we investigated morphology, proliferative capacity, and motility of VIMSA/SA astrocytes, and their effect on the differentiation of neural stem/progenitor cells. VIMSA/SA astrocytes expressed less vimentin and more GFAP but showed a well-developed intermediate filament network, exhibited normal cell morphology, proliferation, and motility in an in vitro wound closing assay. Interestingly, we found a two- to fourfold increased neuronal differentiation of VIMSA/SA neurosphere cells, both in a standard 2D and in Bioactive3D cell culture systems, and determined that this effect was neurosphere cell autonomous and not dependent on cocultured astrocytes. Using BrdU in vivo labeling to assess neural stem/progenitor cell proliferation and differentiation in the hippocampus of adult mice, one of the two major adult neurogenic regions, we found a modest increase (by 8%) in the fraction of newly born and surviving neurons. Thus, mutation of the serine sites phosphorylated in vimentin during mitosis alters intermediate filament protein expression but has no effect on astrocyte morphology or proliferation, and leads to increased neuronal differentiation of neural progenitor cells.- Published
- 2018
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21. Attenuation of reactive gliosis in stroke-injured mouse brain does not affect neurogenesis from grafted human iPSC-derived neural progenitors.
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Laterza C, Uoshima N, Tornero D, Wilhelmsson U, Stokowska A, Ge R, Pekny M, Lindvall O, and Kokaia Z
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- Animals, Glial Fibrillary Acidic Protein genetics, Humans, Male, Mice, Mice, Inbred C57BL, Mutation, Gliosis prevention & control, Induced Pluripotent Stem Cells transplantation, Neural Stem Cells transplantation, Neurogenesis, Stroke pathology
- Abstract
Induced pluripotent stem cells (iPSCs) or their progeny, derived from human somatic cells, can give rise to functional improvements after intracerebral transplantation in animal models of stroke. Previous studies have indicated that reactive gliosis, which is associated with stroke, inhibits neurogenesis from both endogenous and grafted neural stem/progenitor cells (NSPCs) of rodent origin. Here we have assessed whether reactive astrocytes affect the fate of human iPSC-derived NSPCs transplanted into stroke-injured brain. Mice with genetically attenuated reactive gliosis (deficient for GFAP and vimentin) were subjected to cortical stroke and cells were implanted adjacent to the ischemic lesion one week later. At 8 weeks after transplantation, immunohistochemical analysis showed that attenuated reactive gliosis did not affect neurogenesis or commitment towards glial lineage of the grafted NSPCs. Our findings, obtained in a human-to-mouse xenograft experiment, provide evidence that the reactive gliosis in stroke-injured brain does not affect the formation of new neurons from intracortically grafted human iPSC-derived NSPCs. However, for a potential clinical translation of these cells in stroke, it will be important to clarify whether the lack of effect of reactive gliosis on neurogenesis is observed also in a human-to-human experimental setting.
- Published
- 2018
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22. Neural Progenitor Cells in Cerebral Cortex of Epilepsy Patients do not Originate from Astrocytes Expressing GLAST.
- Author
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Chen M, Puschmann TB, Wilhelmsson U, Örndal C, Pekna M, Malmgren K, Rydenhag B, and Pekny M
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- Adolescent, Adult, Astrocytes pathology, Cells, Cultured, Cerebral Cortex pathology, Cerebral Cortex surgery, Child, Child, Preschool, Drug Resistant Epilepsy pathology, Drug Resistant Epilepsy surgery, Female, Gray Matter metabolism, Gray Matter pathology, Gray Matter surgery, Humans, Male, Middle Aged, Multipotent Stem Cells metabolism, Multipotent Stem Cells pathology, Neural Stem Cells pathology, Young Adult, Astrocytes metabolism, Cerebral Cortex metabolism, Drug Resistant Epilepsy metabolism, Excitatory Amino Acid Transporter 1 metabolism, Neural Stem Cells metabolism, Neurogenesis physiology
- Abstract
Adult neurogenesis in human brain is known to occur in the hippocampus, the subventricular zone, and the striatum. Neural progenitor cells (NPCs) were reported in the cortex of epilepsy patients; however, their identity is not known. Since astrocytes were proposed as the source of neural progenitors in both healthy and diseased brain, we tested the hypothesis that NPCs in the epileptic cortex originate from reactive, alternatively, de-differentiated astrocytes that express glutamate aspartate transporter (GLAST). We assessed the capacity to form neurospheres and the differentiation potential of cells dissociated from fresh cortical tissue from patients who underwent surgical treatment for pharmacologically intractable epilepsy. Neurospheres were generated from 57% of cases (8/14). Upon differentiation, the neurosphere cells gave rise to neurons, oligodendrocytes, and astrocytes. Sorting of dissociated cells showed that only cells negative for GLAST formed neurospheres. In conclusion, we show that cells with neural stem cell properties are present in brain cortex of epilepsy patients, and that these cells are not GLAST-positive astrocytes., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2017
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23. Injury Leads to the Appearance of Cells with Characteristics of Both Microglia and Astrocytes in Mouse and Human Brain.
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Wilhelmsson U, Andersson D, de Pablo Y, Pekny R, Ståhlberg A, Mulder J, Mitsios N, Hortobágyi T, Pekny M, and Pekna M
- Subjects
- Alzheimer Disease pathology, Animals, Apoptosis Inducing Factor genetics, Apoptosis Inducing Factor metabolism, Astrocytes metabolism, Brain Injuries metabolism, CD11b Antigen genetics, CD11b Antigen metabolism, CX3C Chemokine Receptor 1 genetics, CX3C Chemokine Receptor 1 metabolism, Cell Hypoxia drug effects, Cells, Cultured, Dementia pathology, Glial Fibrillary Acidic Protein metabolism, Glucose deficiency, Hippocampus pathology, Humans, Lipopolysaccharides pharmacology, Male, Mice, Mice, Inbred C57BL, Mice, Transgenic, Microglia drug effects, Microglia metabolism, Astrocytes pathology, Brain Injuries pathology, Entorhinal Cortex pathology, Gene Expression Regulation physiology, Microglia pathology
- Abstract
Microglia and astrocytes have been considered until now as cells with very distinct identities. Here, we assessed the heterogeneity within microglia/monocyte cell population in mouse hippocampus and determined their response to injury, by using single-cell gene expression profiling of cells isolated from uninjured and deafferented hippocampus. We found that in individual cells, microglial markers Cx3cr1, Aif1, Itgam, and Cd68 were co-expressed. Interestingly, injury led to the co-expression of the astrocyte marker Gfap in a subpopulation of Cx3cr1-expressing cells from both the injured and contralesional hippocampus. Cells co-expressing astrocyte and microglia markers were also detected in the in vitro LPS activation/injury model and in sections from human brain affected by stroke, Alzheimer's disease, and Lewy body dementia. Our findings indicate that injury and chronic neurodegeneration lead to the appearance of cells that share molecular characteristics of both microglia and astrocytes, 2 cell types with distinct embryologic origin and function., (© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2017
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24. Heterogeneity of Notch signaling in astrocytes and the effects of GFAP and vimentin deficiency.
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Lebkuechner I, Wilhelmsson U, Möllerström E, Pekna M, and Pekny M
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- Animals, Epidermal Growth Factor genetics, Hippocampus cytology, Intercellular Signaling Peptides and Proteins genetics, Intercellular Signaling Peptides and Proteins physiology, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Primary Cell Culture, RNA, Messenger biosynthesis, RNA, Messenger genetics, Receptor, Notch1, SOXB1 Transcription Factors, Astrocytes physiology, Glial Fibrillary Acidic Protein deficiency, Glial Fibrillary Acidic Protein genetics, Receptors, Notch genetics, Receptors, Notch physiology, Signal Transduction genetics, Signal Transduction physiology, Vimentin deficiency, Vimentin genetics
- Abstract
Astrocytes have multiple roles in the CNS including control of adult neurogenesis. We recently showed that astrocyte inhibition of neurogenesis through Notch signaling depends on the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin. Here, we used real-time quantitative PCR to analyze gene expression in individual mouse astrocytes in primary cultures and in GFAP(POS) or Aldh1L1(POS) astrocytes freshly isolated from uninjured, contralesional and lesioned hippocampus 4 days after entorhinal cortex lesion. To determine the Notch signaling competence of individual astrocytes, we measured the mRNA levels of Notch ligands and Notch1 receptor. We found that whereas most cultured and freshly isolated astrocytes were competent to receive Notch signals, only a minority of astrocytes were competent to send Notch signals. Injury increased the fraction of astrocyte subpopulation unable to send and receive Notch signals, thus resembling primary astrocytes in vitro. Astrocytes deficient of GFAP and vimentin showed decreased Notch signal sending competence and altered expression of Notch signaling pathway-related genes Dlk2, Notch1, and Sox2. Furthermore, we identified astrocyte subpopulations based on their mRNA and protein expression of nestin and HB-EGF. This study improves our understanding of astrocyte heterogeneity, and points to astrocyte cytoplasmic intermediate filaments as targets for neural cell replacement strategies., (© 2015 International Society for Neurochemistry.)
- Published
- 2015
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25. Classification of subpopulations of cells within human primary brain tumors by single cell gene expression profiling.
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Möllerström E, Rydenhag B, Andersson D, Lebkuechner I, Puschmann TB, Chen M, Wilhelmsson U, Ståhlberg A, Malmgren K, and Pekny M
- Subjects
- Astrocytoma genetics, Astrocytoma pathology, Brain Neoplasms classification, Humans, Male, Middle Aged, Oligodendroglioma genetics, Oligodendroglioma pathology, Brain Neoplasms genetics, Brain Neoplasms pathology, Gene Expression Profiling, Single-Cell Analysis
- Abstract
Brain tumors are heterogeneous with respect to genetic and histological properties of cells within the tumor tissue. To study subpopulations of cells, we developed a protocol for obtaining viable single cells from freshly isolated human brain tissue for single cell gene expression profiling. We evaluated this technique for characterization of cell populations within brain tumor and tumor penumbra. Fresh tumor tissue was obtained from one astrocytoma grade IV and one oligodendroglioma grade III tumor as well as the tumor penumbra of the latter tumor. The tissue was dissociated into individual cells and the expression of 36 genes was assessed by reverse transcription quantitative PCR followed by data analysis. We show that tumor cells from both the astrocytoma grade IV and oligodendroglioma grade III tumor constituted cell subpopulations defined by their gene expression profiles. Some cells from the oligodendroglioma grade III tumor proper shared molecular characteristics with the cells from the penumbra of the same tumor suggesting that a subpopulation of cells within the oligodendroglioma grade III tumor consisted of normal brain cells. We conclude that subpopulations of tumor cells can be identified by using single cell gene expression profiling.
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- 2015
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26. Beneficial effects of gfap/vimentin reactive astrocytes for axonal remodeling and motor behavioral recovery in mice after stroke.
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Liu Z, Li Y, Cui Y, Roberts C, Lu M, Wilhelmsson U, Pekny M, and Chopp M
- Subjects
- Animals, Axons pathology, Biotin analogs & derivatives, Brain Infarction etiology, Calcium-Binding Proteins metabolism, Dextrans, Disease Models, Animal, Gene Expression Regulation genetics, Gene Expression Regulation physiology, Glial Fibrillary Acidic Protein genetics, Mice, Mice, Inbred C57BL, Mice, Transgenic, Microfilament Proteins metabolism, Movement Disorders etiology, Nerve Tissue Proteins genetics, Nerve Tissue Proteins metabolism, Pyramidal Tracts pathology, Thrombosis etiology, Versicans metabolism, Vimentin genetics, Glial Fibrillary Acidic Protein metabolism, Nerve Regeneration genetics, Recovery of Function genetics, Stroke pathology, Stroke physiopathology, Vimentin metabolism
- Abstract
The functional role of reactive astrocytes after stroke is controversial. To elucidate whether reactive astrocytes contribute to neurological recovery, we compared behavioral outcome, axonal remodeling of the corticospinal tract (CST), and the spatio-temporal change of chondroitin sulfate proteoglycan (CSPG) expression between wild-type (WT) and glial fibrillary acidic protein/vimentin double knockout (GFAP(-/-) Vim(-/-) ) mice subjected to Rose Bengal induced cerebral cortical photothrombotic stroke in the right forelimb motor area. A foot-fault test and a single pellet reaching test were performed prior to and on day 3 after stroke, and weekly thereafter to monitor functional deficit and recovery. Biotinylated dextran amine (BDA) was injected into the left motor cortex to anterogradely label the CST axons. Compared with WT mice, the motor functional recovery and BDA-positive CST axonal length in the denervated side of the cervical gray matter were significantly reduced in GFAP(-/-) Vim(-/-) mice (n = 10/group, P < 0.01). Immunohistological data showed that in GFAP(-/-) Vim(-/-) mice, in which astrocytic reactivity is attenuated, CSPG expression was significantly increased in the lesion remote areas in both hemispheres, but decreased in the ischemic lesion boundary zone, compared with WT mice (n = 12/group, P < 0.001). Our data suggest that attenuated astrocytic reactivity impairs or delays neurological recovery by reducing CST axonal remodeling in the denervated spinal cord. Thus, manipulation of astrocytic reactivity post stroke may represent a therapeutic target for neurorestorative strategies., (© 2014 Wiley Periodicals, Inc.)
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- 2014
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27. The dual role of astrocyte activation and reactive gliosis.
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Pekny M, Wilhelmsson U, and Pekna M
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- Animals, Astrocytes pathology, Brain Injuries metabolism, Brain Injuries pathology, Brain Ischemia metabolism, Brain Ischemia pathology, Cell Communication, Female, Gliosis pathology, Humans, Male, Microglia physiology, Nerve Degeneration metabolism, Nerve Degeneration pathology, Sex Factors, Spinal Injuries metabolism, Spinal Injuries pathology, Astrocytes physiology, Gliosis metabolism
- Abstract
Astrocyte activation and reactive gliosis accompany most of the pathologies in the brain, spinal cord, and retina. Reactive gliosis has been described as constitutive, graded, multi-stage, and evolutionary conserved defensive astroglial reaction [Verkhratsky and Butt (2013) In: Glial Physiology and Pathophysiology]. A well- known feature of astrocyte activation and reactive gliosis are the increased production of intermediate filament proteins (also known as nanofilament proteins) and remodeling of the intermediate filament system of astrocytes. Activation of astrocytes is associated with changes in the expression of many genes and characteristic morphological hallmarks, and has important functional consequences in situations such as stroke, trauma, epilepsy, Alzheimer's disease (AD), and other neurodegenerative diseases. The impact of astrocyte activation and reactive gliosis on the pathogenesis of different neurological disorders is not yet fully understood but the available experimental evidence points to many beneficial aspects of astrocyte activation and reactive gliosis that range from isolation and sequestration of the affected region of the central nervous system (CNS) from the neighboring tissue that limits the lesion size to active neuroprotection and regulation of the CNS homeostasis in times of acute ischemic, osmotic, or other kinds of stress. The available experimental data from selected CNS pathologies suggest that if not resolved in time, reactive gliosis can exert inhibitory effects on several aspects of neuroplasticity and CNS regeneration and thus might become a target for future therapeutic interventions., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)
- Published
- 2014
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28. Synemin is expressed in reactive astrocytes and Rosenthal fibers in Alexander disease.
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Pekny T, Faiz M, Wilhelmsson U, Curtis MA, Matej R, Skalli O, and Pekny M
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- Adolescent, Alexander Disease genetics, Alexander Disease pathology, Astrocytes pathology, Brain metabolism, Brain pathology, Child, Female, Glial Fibrillary Acidic Protein genetics, Gliosis metabolism, Gliosis pathology, Humans, Immunohistochemistry, Point Mutation, Tissue Distribution, Alexander Disease metabolism, Astrocytes metabolism, Glial Fibrillary Acidic Protein metabolism, Intermediate Filament Proteins metabolism
- Abstract
Alexander disease (AxD) is a neurodegenerative disorder with prominent white matter degeneration and the presence of Rosenthal fibers containing aggregates of glial fibrillary acidic protein (GFAP), and small stress proteins HSP27 and αB-crystallin, and widespread reactive gliosis. AxD is caused by mutations in GFAP, the main astrocyte intermediate filament protein. We previously showed that intermediate filament protein synemin is upregulated in reactive astrocytes after neurotrauma. Here, we examined immunohistochemically the presence of synemin in reactive astrocytes and Rosenthal fibers in two patients with AxD. There was an abundance of GFAP-positive Rosenthal fibers and widespread reactive gliosis in the white matter and subpial regions. Many of the GFAP-positive reactive astrocytes were positive for synemin, and synemin was also present in Rosenthal fibers. We show that synemin is expressed in reactive astrocytes in AxD, and is also present in Rosenthal fibers. The potential role of synemin in AxD pathogenesis remains to be investigated., (© 2013 APMIS Published by Blackwell Publishing Ltd.)
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- 2014
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29. Axonal regeneration after sciatic nerve lesion is delayed but complete in GFAP- and vimentin-deficient mice.
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Berg A, Zelano J, Pekna M, Wilhelmsson U, Pekny M, and Cullheim S
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- Animals, Axotomy, Female, Glial Fibrillary Acidic Protein metabolism, Mice, Motor Neurons pathology, Muscles innervation, Myelin Sheath physiology, Recovery of Function, Sciatic Nerve pathology, Sciatic Nerve physiopathology, Sciatic Neuropathy metabolism, Sciatic Neuropathy pathology, Synapses pathology, Up-Regulation, Vimentin metabolism, Axons pathology, Glial Fibrillary Acidic Protein deficiency, Nerve Regeneration, Sciatic Neuropathy physiopathology, Vimentin deficiency
- Abstract
Peripheral axotomy of motoneurons triggers Wallerian degeneration of injured axons distal to the lesion, followed by axon regeneration. Centrally, axotomy induces loss of synapses (synaptic stripping) from the surface of lesioned motoneurons in the spinal cord. At the lesion site, reactive Schwann cells provide trophic support and guidance for outgrowing axons. The mechanisms of synaptic stripping remain elusive, but reactive astrocytes and microglia appear to be important in this process. We studied axonal regeneration and synaptic stripping of motoneurons after a sciatic nerve lesion in mice lacking the intermediate filament (nanofilament) proteins glial fibrillary acidic protein (GFAP) and vimentin, which are upregulated in reactive astrocytes and Schwann cells. Seven days after sciatic nerve transection, ultrastructural analysis of synaptic density on the somata of injured motoneurons revealed more remaining boutons covering injured somata in GFAP(-/-)Vim(-/-) mice. After sciatic nerve crush in GFAP(-/-)Vim(-/-) mice, the fraction of reinnervated motor endplates on muscle fibers of the gastrocnemius muscle was reduced 13 days after the injury, and axonal regeneration and functional recovery were delayed but complete. Thus, the absence of GFAP and vimentin in glial cells does not seem to affect the outcome after peripheral motoneuron injury but may have an important effect on the response dynamics.
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- 2013
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30. Astrocytoma grade IV (glioblastoma multiforme) displays 3 subtypes with unique expression profiles of intermediate filament proteins.
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Skalli O, Wilhelmsson U, Orndahl C, Fekete B, Malmgren K, Rydenhag B, and Pekny M
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- Biomarkers, Tumor metabolism, Brain Neoplasms metabolism, Brain Neoplasms surgery, Female, Glial Fibrillary Acidic Protein metabolism, Glioblastoma metabolism, Glioblastoma mortality, Glioblastoma surgery, Humans, Male, Middle Aged, Nerve Tissue Proteins metabolism, Nestin, Retrospective Studies, Spinal Cord Neoplasms metabolism, Spinal Cord Neoplasms mortality, Spinal Cord Neoplasms surgery, Survival Rate, Sweden epidemiology, Vimentin metabolism, Brain Neoplasms pathology, Glioblastoma secondary, Intermediate Filament Proteins metabolism, Spinal Cord Neoplasms pathology
- Abstract
Astrocytoma grade IV (glioblastoma multiforme) is the most common and most malignant tumor of the central nervous system and is currently noncurable. Here, we have examined a population-based cohort of 47 patients with grade IV astrocytoma, who underwent tumor surgery at Sahlgrenska University Hospital in Sweden and who survived after surgery for less than 200 days (short survivors, 28 patients) and more than 500 days (long survivors, 19 patients). For each tumor, we ascertained information on patient age, sex, tumor location, oncological treatment, and survival after surgery. The analysis of the tumor volume and the extent of tumor resection (incomplete versus complete resection of the macroscopic tumor) was made retrospectively from the preoperative radiological investigations and, when available, also from postoperative radiology. We performed semiquantitative immunohistochemical evaluation of the presence of intermediate filament (nanofilament) proteins glial fibrillary acidic protein, vimentin, nestin, and synemin in tumor cells. The intermediate filament system helps cells and tissues to cope with various types of stress, and thus, it might affect the malignant potential of grade IV astrocytoma. We propose a subclassification of astrocytomas grade IV with respect to the expression of the intermediate filament proteins glial fibrillary acidic protein, vimentin, nestin, and synemin, namely, type A, B, and C. Our results suggest that the expression of the intermediate filament proteins glial fibrillary acidic protein, vimentin, nestin, and synemin is coregulated in grade IV astrocytomas. The expression patterns of the intermediate filament proteins in astrocytoma type A, B, and C might have biological and clinical significance., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
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31. Plasticity response in the contralesional hemisphere after subtle neurotrauma: gene expression profiling after partial deafferentation of the hippocampus.
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Andersson D, Wilhelmsson U, Nilsson M, Kubista M, Ståhlberg A, Pekna M, and Pekny M
- Subjects
- Afferent Pathways injuries, Animals, Astrocytes metabolism, Astrocytes pathology, Cerebrum injuries, Craniocerebral Trauma physiopathology, Cytoskeletal Proteins genetics, Cytoskeletal Proteins metabolism, Entorhinal Cortex injuries, Gene Expression Profiling, Glial Fibrillary Acidic Protein, Hippocampus injuries, Male, Mice, Mice, Knockout, Nerve Tissue Proteins deficiency, Nerve Tissue Proteins genetics, Stereotaxic Techniques, Synaptotagmin I genetics, Synaptotagmin I metabolism, Thrombospondins genetics, Thrombospondins metabolism, Vimentin deficiency, Vimentin genetics, Afferent Pathways metabolism, Cerebrum metabolism, Craniocerebral Trauma metabolism, Entorhinal Cortex metabolism, Gene Expression Regulation, Hippocampus metabolism, Neuronal Plasticity
- Abstract
Neurotrauma or focal brain ischemia are known to trigger molecular and structural responses in the uninjured hemisphere. These responses may have implications for tissue repair processes as well as for the recovery of function. To determine whether the plasticity response in the uninjured hemisphere occurs even after a subtle trauma, we subjected mice to a partial unilateral deafferentation of the hippocampus induced by stereotactically performed entorhinal cortex lesion (ECL). The expression of selected genes was assessed by quantitative real-time PCR in the hippocampal tissue at the injured side and the contralesional side at day 4 and 14 after injury. We observed that expression of genes coding for synaptotagmin 1, ezrin, thrombospondin 4, and C1q proteins, that have all been implicated in the synapse formation, re-arrangement and plasticity, were upregulated both in the injured and the contralesional hippocampus, implying a plasticity response in the uninjured hemisphere. Several of the genes, the expression of which was altered in response to ECL, are known to be expressed in astrocytes. To test whether astrocyte activation plays a role in the observed plasticity response to ECL, we took advantage of mice deficient in two intermediate filament (nanofilament) proteins glial fibrillary acidic protein (GFAP) and vimentin (GFAP(-/-)Vim(-/-) ) and exhibiting attenuated astrocyte activation and reactive gliosis. The absence of GFAP and vimentin reduced the ECL-induced upregulation of thrombospondin 4, indicating that this response to ECL depends on astrocyte activation and reactive gliosis. We conclude that even a very limited focal neurotrauma triggers a distinct response at the contralesional side, which at least to some extent depends on astrocyte activation.
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- 2013
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32. Versatile and simple approach to determine astrocyte territories in mouse neocortex and hippocampus.
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Grosche A, Grosche J, Tackenberg M, Scheller D, Gerstner G, Gumprecht A, Pannicke T, Hirrlinger PG, Wilhelmsson U, Hüttmann K, Härtig W, Steinhäuser C, Pekny M, and Reichenbach A
- Subjects
- Aging metabolism, Animals, Astrocytes metabolism, Cell Count, Female, Golgi Apparatus metabolism, Male, Mice, Reproducibility of Results, S100 Proteins metabolism, Staining and Labeling, Astrocytes cytology, Cell Size, Cytological Techniques methods, Hippocampus cytology, Neocortex cytology
- Abstract
Background: Besides their neuronal support functions, astrocytes are active partners in neuronal information processing. The typical territorial structure of astrocytes (the volume of neuropil occupied by a single astrocyte) is pivotal for many aspects of glia-neuron interactions., Methods: Individual astrocyte territorial volumes are measured by Golgi impregnation, and astrocyte densities are determined by S100β immunolabeling. These data are compared with results from conventionally applied methods such as dye filling and determination of the density of astrocyte networks by biocytin loading. Finally, we implemented our new approach to investigate age-related changes in astrocyte territories in the cortex and hippocampus of 5- and 21-month-old mice., Results: The data obtained by our simplified approach based on Golgi impregnation were compared to previously published dye filling experiments, and yielded remarkably comparable results regarding astrocyte territorial volumes. Moreover, we found that almost all coupled astrocytes (as indicated by biocytin loading) were immunopositive for S100β. A first application of this new experimental approach gives insight in age-dependent changes in astrocyte territorial volumes. They increased with age, while cell densities remained stable. In 5-month-old mice, the overlap factor was close to 1, revealing little or no interdigitation of astrocyte territories. However, in 21-month-old mice, the overlap factor was more than 2, suggesting that processes of adjacent astrocytes interdigitate., Conclusion: Here we verified the usability of a simple, versatile method for assessing astrocyte territories and the overlap factor between adjacent territories. Second, we found that there is an age-related increase in territorial volumes of astrocytes that leads to loss of the strict organization in non-overlapping territories. Future studies should elucidate the physiological relevance of this adaptive reaction of astrocytes in the aging brain and the methods presented in this study might be a powerful tool to do so.
- Published
- 2013
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33. Attenuating astrocyte activation accelerates plaque pathogenesis in APP/PS1 mice.
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Kraft AW, Hu X, Yoon H, Yan P, Xiao Q, Wang Y, Gil SC, Brown J, Wilhelmsson U, Restivo JL, Cirrito JR, Holtzman DM, Kim J, Pekny M, and Lee JM
- Subjects
- Animals, Blotting, Western, Enzyme-Linked Immunosorbent Assay, Immunohistochemistry, Mice, Real-Time Polymerase Chain Reaction, Amyloid beta-Protein Precursor genetics, Astrocytes cytology, Presenilin-1 genetics
- Abstract
The accumulation of aggregated amyloid-β (Aβ) in amyloid plaques is a neuropathological hallmark of Alzheimer's disease (AD). Reactive astrocytes are intimately associated with amyloid plaques; however, their role in AD pathogenesis is unclear. We deleted the genes encoding two intermediate filament proteins required for astrocyte activation-glial fibrillary acid protein (Gfap) and vimentin (Vim)-in transgenic mice expressing mutant human amyloid precursor protein and presenilin-1 (APP/PS1). The gene deletions increased amyloid plaque load: APP/PS1 Gfap(-/-)Vim(-/-) mice had twice the plaque load of APP/PS1 Gfap(+/+)Vim(+/+) mice at 8 and 12 mo of age. APP expression and soluble and interstitial fluid Aβ levels were unchanged, suggesting that the deletions had no effect on APP processing or Aβ generation. Astrocyte morphology was markedly altered by the deletions: wild-type astrocytes had hypertrophied processes that surrounded and infiltrated plaques, whereas Gfap(-/-)Vim(-/-) astrocytes had little process hypertrophy and lacked contact with adjacent plaques. Moreover, Gfap and Vim gene deletion resulted in a marked increase in dystrophic neurites (2- to 3-fold higher than APP/PS1 Gfap(+/+)Vim(+/+) mice), even after normalization for amyloid load. These results suggest that astrocyte activation limits plaque growth and attenuates plaque-related dystrophic neurites. These activities may require intimate contact between astrocyte and plaque.
- Published
- 2013
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34. Astrocytes negatively regulate neurogenesis through the Jagged1-mediated Notch pathway.
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Wilhelmsson U, Faiz M, de Pablo Y, Sjöqvist M, Andersson D, Widestrand A, Potokar M, Stenovec M, Smith PL, Shinjyo N, Pekny T, Zorec R, Ståhlberg A, Pekna M, Sahlgren C, and Pekny M
- Subjects
- Amyloid Precursor Protein Secretases genetics, Amyloid Precursor Protein Secretases metabolism, Animals, Astrocytes cytology, Calcium-Binding Proteins metabolism, Cell Communication genetics, Cell Differentiation, Coculture Techniques, Endocytosis, Gene Expression Regulation, Developmental, Glial Fibrillary Acidic Protein, Intercellular Signaling Peptides and Proteins metabolism, Jagged-1 Protein, Male, Membrane Proteins metabolism, Mice, Mice, Knockout, Nerve Tissue Proteins deficiency, Primary Cell Culture, Receptors, Notch metabolism, Serrate-Jagged Proteins, Signal Transduction, Stem Cells cytology, Stem Cells metabolism, Vimentin deficiency, Wnt Proteins genetics, Wnt Proteins metabolism, Astrocytes metabolism, Calcium-Binding Proteins genetics, Intercellular Signaling Peptides and Proteins genetics, Membrane Proteins genetics, Nerve Tissue Proteins genetics, Neurogenesis genetics, Receptors, Notch genetics, Vimentin genetics
- Abstract
Adult neurogenesis is regulated by a number of cellular players within the neurogenic niche. Astrocytes participate actively in brain development, regulation of the mature central nervous system (CNS), and brain plasticity. They are important regulators of the local environment in adult neurogenic niches through the secretion of diffusible morphogenic factors, such as Wnts. Astrocytes control the neurogenic niche also through membrane-associated factors, however, the identity of these factors and the mechanisms involved are largely unknown. In this study, we sought to determine the mechanisms underlying our earlier finding of increased neuronal differentiation of neural progenitor cells when cocultured with astrocytes lacking glial fibrillary acidic protein (GFAP) and vimentin (GFAP(-/-) Vim(-/-) ). We used primary astrocyte and neurosphere cocultures to demonstrate that astrocytes inhibit neuronal differentiation through a cell-cell contact. GFAP(-/-) Vim(-/-) astrocytes showed reduced endocytosis of Notch ligand Jagged1, reduced Notch signaling, and increased neuronal differentiation of neurosphere cultures. This effect of GFAP(-/-) Vim(-/-) astrocytes was abrogated in the presence of immobilized Jagged1 in a manner dependent on the activity of γ-secretase. Finally, we used GFAP(-/-) Vim(-/-) mice to show that in the absence of GFAP and vimentin, hippocampal neurogenesis under basal conditions as well as after injury is increased. We conclude that astrocytes negatively regulate neurogenesis through the Notch pathway, and endocytosis of Notch ligand Jagged1 in astrocytes and Notch signaling from astrocytes to neural stem/progenitor cells depends on the intermediate filament proteins GFAP and vimentin., (Copyright © 2012 AlphaMed Press.)
- Published
- 2012
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35. Reactive glial cells: increased stiffness correlates with increased intermediate filament expression.
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Lu YB, Iandiev I, Hollborn M, Körber N, Ulbricht E, Hirrlinger PG, Pannicke T, Wei EQ, Bringmann A, Wolburg H, Wilhelmsson U, Pekny M, Wiedemann P, Reichenbach A, and Käs JA
- Subjects
- Animals, Biomechanical Phenomena, Glial Fibrillary Acidic Protein, Gliosis metabolism, Gliosis pathology, Mice, Mice, Knockout, Nerve Tissue Proteins genetics, Nerve Tissue Proteins metabolism, Rats, Rats, Long-Evans, Reperfusion Injury, Vimentin genetics, Vimentin metabolism, Gene Expression Regulation physiology, Intermediate Filaments metabolism, Neuroglia cytology, Neuroglia physiology
- Abstract
Increased stiffness of reactive glial cells may impede neurite growth and contribute to the poor regenerative capabilities of the mammalian central nervous system. We induced reactive gliosis in rodent retina by ischemia-reperfusion and assessed intermediate filament (IF) expression and the viscoelastic properties of dissociated single glial cells in wild-type mice, mice lacking glial fibrillary acidic protein and vimentin (GFAP(-/-)Vim(-/-)) in which glial cells are consequently devoid of IFs, and normal Long-Evans rats. In response to ischemia-reperfusion, glial cells stiffened significantly in wild-type mice and rats but were unchanged in GFAP(-/-)Vim(-/-) mice. Cell stiffness (elastic modulus) correlated with the density of IFs. These results support the hypothesis that rigid glial scars impair nerve regeneration and that IFs are important determinants of cellular viscoelasticity in reactive glia. Thus, therapeutic suppression of IF up-regulation in reactive glial cells may facilitate neuroregeneration.
- Published
- 2011
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36. Expression of plasminogen activator inhibitor-1 and protease nexin-1 in human astrocytes: Response to injury-related factors.
- Author
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Hultman K, Blomstrand F, Nilsson M, Wilhelmsson U, Malmgren K, Pekny M, Kousted T, Jern C, and Tjärnlund-Wolf A
- Subjects
- Brain Chemistry, Brain Injuries pathology, Cell Hypoxia, Cells, Cultured, Cytokines biosynthesis, Enzyme-Linked Immunosorbent Assay, Gene Expression physiology, Glial Fibrillary Acidic Protein biosynthesis, Glial Fibrillary Acidic Protein genetics, Humans, Hypoxia, Brain pathology, Immunohistochemistry, Protease Nexins, RNA, Messenger biosynthesis, RNA, Messenger genetics, Serpin E2, Serpins biosynthesis, Tumor Necrosis Factor-alpha metabolism, Amyloid beta-Protein Precursor biosynthesis, Astrocytes metabolism, Brain Injuries metabolism, Plasminogen Activator Inhibitor 1 biosynthesis, Receptors, Cell Surface biosynthesis
- Abstract
Astrocytes play a diverse role in central nervous system (CNS) injury. Production of the serine protease inhibitors (serpins) plasminogen activator inhibitor-1 (PAI-1) and protease nexin-1 (PN-1) by astrocytes may counterbalance excessive serine protease activity associated with CNS pathologies such as ischemic stroke. Knowledge regarding the regulation of these genes in the brain is limited, so the objective of the present study was to characterize the effects of injury-related factors on serpin expression in human astrocytes. Native human astrocytes were exposed to hypoxia or cytokines, including interleukin-6 (IL-6), IL-1beta, tumor necrosis factor-alpha (TNF-alpha), IL-10, transforming growth factor-alpha (TGF-alpha), and TGF-beta for 0-20 hr. Serpin mRNA expression and protein secretion were determined by real-time RT-PCR and ELISA, respectively. Localization of PAI-1 and PN-1 in human brain tissue was examined by immunohistochemistry. Hypoxia and all assayed cytokines induced a significant increase in PAI-1 expression, whereas prolonged treatment with IL-1beta or TNF-alpha resulted in a significant down-regulation. The most pronounced induction of both PAI-1 and PN-1 was observed following early treatment with TGF-alpha. In contrast to PAI-1, the PN-1 gene did not respond to hypoxia. Positive immunoreactivity for PAI-1 in human brain tissue was demonstrated in reactive astrocytes within gliotic areas of temporal cortex. We show here that human astrocytes express PAI-1 and PN-1 and demonstrate that this astrocytic expression is regulated in a dynamic manner by injury-related factors., ((c) 2010 Wiley-Liss, Inc.)
- Published
- 2010
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37. Attenuation of reactive gliosis does not affect infarct volume in neonatal hypoxic-ischemic brain injury in mice.
- Author
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Järlestedt K, Rousset CI, Faiz M, Wilhelmsson U, Ståhlberg A, Sourkova H, Pekna M, Mallard C, Hagberg H, and Pekny M
- Subjects
- Animals, Animals, Newborn, Astrocytes, Cell Survival, Glial Fibrillary Acidic Protein deficiency, Mice, Mice, Knockout, Neurons, Brain Infarction pathology, Gliosis pathology, Hypoxia-Ischemia, Brain pathology
- Abstract
Background: Astroglial cells are activated following injury and up-regulate the expression of the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin. Adult mice lacking the intermediate filament proteins GFAP and vimentin (GFAP(-/-)Vim(-/-)) show attenuated reactive gliosis, reduced glial scar formation and improved regeneration of neuronal synapses after neurotrauma. GFAP(-/-)Vim(-/-) mice exhibit larger brain infarcts after middle cerebral artery occlusion suggesting protective role of reactive gliosis after adult focal brain ischemia. However, the role of astrocyte activation and reactive gliosis in the injured developing brain is unknown., Methodology/principal Findings: We subjected GFAP(-/-)Vim(-/-) and wild-type mice to unilateral hypoxia-ischemia (HI) at postnatal day 9 (P9). Bromodeoxyuridine (BrdU; 25 mg/kg) was injected intraperitoneally twice daily from P9 to P12. On P12 and P31, the animals were perfused intracardially. Immunohistochemistry with MAP-2, BrdU, NeuN, and S100 antibodies was performed on coronal sections. We found no difference in the hemisphere or infarct volume between GFAP(-/-)Vim(-/-) and wild-type mice at P12 and P31, i.e. 3 and 22 days after HI. At P31, the number of NeuN(+) neurons in the ischemic and contralateral hemisphere was comparable between GFAP(-/-)Vim(-/-) and wild-type mice. In wild-type mice, the number of S100(+) astrocytes was lower in the ipsilateral compared to contralateral hemisphere (65.0+/-50.1 vs. 85.6+/-34.0, p<0.05). In the GFAP(-/-)Vim(-/-) mice, the number of S100(+) astrocytes did not differ between the ischemic and contralateral hemisphere at P31. At P31, GFAP(-/-)Vim(-/-) mice showed an increase in NeuN(+)BrdU(+) (surviving newly born) neurons in the ischemic cortex compared to wild-type mice (6.7+/-7.7; n = 29 versus 2.9+/-3.6; n = 28, respectively, p<0.05), but a comparable number of S100(+)BrdU(+) (surviving newly born) astrocytes., Conclusions/significance: Our results suggest that attenuation of reactive gliosis in the developing brain does not affect the hemisphere or infarct volume after HI, but increases the number of surviving newborn neurons.
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- 2010
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38. Abnormal reactivity of muller cells after retinal detachment in mice deficient in GFAP and vimentin.
- Author
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Verardo MR, Lewis GP, Takeda M, Linberg KA, Byun J, Luna G, Wilhelmsson U, Pekny M, Chen DF, and Fisher SK
- Subjects
- Animals, Disease Models, Animal, Fluorescent Antibody Technique, Indirect, Glial Fibrillary Acidic Protein, Glutamate-Ammonia Ligase metabolism, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Microscopy, Confocal, Microscopy, Electron, Transmission, Neuroglia pathology, Photoreceptor Cells, Vertebrate metabolism, Photoreceptor Cells, Vertebrate pathology, Retina pathology, Retinal Bipolar Cells metabolism, Retinal Bipolar Cells pathology, Retinal Detachment pathology, Retinal Ganglion Cells metabolism, Retinal Ganglion Cells pathology, Retinal Horizontal Cells metabolism, Retinal Horizontal Cells pathology, Rod Opsins metabolism, S100 Proteins metabolism, Up-Regulation, Nerve Tissue Proteins physiology, Neuroglia metabolism, Retina metabolism, Retinal Detachment metabolism, Vimentin physiology
- Abstract
Purpose: To determine the roles of glial fibrillary acidic protein (GFAP) and vimentin in Müller cell reactivity., Methods: Retinal detachments were created in mice deficient for GFAP and vimentin (GFAP(-/-)vim(-/-)) and age-matched wild-type (wt) mice. The reactivity of the retina was studied by immunofluorescence and electron microscopy., Results: Müller cell morphology was different and glutamine synthetase immunoreactivity was reduced in the undisturbed GFAP(-/-)vim(-/-) retinas. After retinal detachment, Müller cells formed subretinal glial scars in the wt mice. In contrast, such scars were not observed in GFAP(-/-)vim(-/-) mice. Müller cells, which normally elongate and thicken in response to detachment, appeared compressed, thin, and "spikey" in the GFAP(-/-)vim(-/-) mice. The end foot region of Müller cells in the GFAP(-/-)vim(-/-) mice often sheared away from the rest of the retina during detachment, corroborating earlier results showing decreased resistance of this region in GFAP(-/-)vim(-/-) retinas to mechanical stress. In regions with end foot shearing, ganglion cells showed intense neurite sprouting, as revealed by anti-neurofilament labeling, a response rarely observed in wt mice., Conclusions: Müller cells are subtly different in the GFAP(-/-)vim(-/-) mouse retina before detachment. The end foot region of these cells may be structurally reinforced by the presence of the intermediate filament cytoskeleton, and our data suggest a critical role for these proteins in Müller cell reaction to retinal detachment and participation in subretinal gliosis.
- Published
- 2008
- Full Text
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39. Protective role of reactive astrocytes in brain ischemia.
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Li L, Lundkvist A, Andersson D, Wilhelmsson U, Nagai N, Pardo AC, Nodin C, Ståhlberg A, Aprico K, Larsson K, Yabe T, Moons L, Fotheringham A, Davies I, Carmeliet P, Schwartz JP, Pekna M, Kubista M, Blomstrand F, Maragakis N, Nilsson M, and Pekny M
- Subjects
- Animals, Astrocytes pathology, Brain Ischemia metabolism, Gap Junctions, Glial Fibrillary Acidic Protein deficiency, Glutamic Acid metabolism, Mice, Mice, Knockout, Middle Cerebral Artery, Vimentin deficiency, Astrocytes physiology, Brain Ischemia pathology, Plasminogen Activator Inhibitor 1 genetics, Receptor, Endothelin B analysis
- Abstract
Reactive astrocytes are thought to protect the penumbra during brain ischemia, but direct evidence has been lacking due to the absence of suitable experimental models. Previously, we generated mice deficient in two intermediate filament (IF) proteins, glial fibrillary acidic protein (GFAP) and vimentin, whose upregulation is the hallmark of reactive astrocytes. GFAP(-/-)Vim(-/-) mice exhibit attenuated posttraumatic reactive gliosis, improved integration of neural grafts, and posttraumatic regeneration. Seven days after middle cerebral artery (MCA) transection, infarct volume was 210 to 350% higher in GFAP(-/-)Vim(-/-) than in wild-type (WT) mice; GFAP(-/-), Vim(-/-) and WT mice had the same infarct volume. Endothelin B receptor (ET(B)R) immunoreactivity was strong on cultured astrocytes and reactive astrocytes around infarct in WT mice but undetectable in GFAP(-/-)Vim(-/-) astrocytes. In WT astrocytes, ET(B)R colocalized extensively with bundles of IFs. GFAP(-/-)Vim(-/-) astrocytes showed attenuated endothelin-3-induced blockage of gap junctions. Total and glutamate transporter-1 (GLT-1)-mediated glutamate transport was lower in GFAP(-/-)Vim(-/-) than in WT mice. DNA array analysis and quantitative real-time PCR showed downregulation of plasminogen activator inhibitor-1 (PAI-1), an inhibitor of tissue plasminogen activator. Thus, reactive astrocytes have a protective role in brain ischemia, and the absence of astrocyte IFs is linked to changes in glutamate transport, ET(B)R-mediated control of gap junctions, and PAI-1 expression.
- Published
- 2008
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40. Increased neurogenesis and astrogenesis from neural progenitor cells grafted in the hippocampus of GFAP-/- Vim-/- mice.
- Author
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Widestrand A, Faijerson J, Wilhelmsson U, Smith PL, Li L, Sihlbom C, Eriksson PS, and Pekny M
- Subjects
- Animals, Astrocytes physiology, Brain Tissue Transplantation, Cell Differentiation, Cells, Cultured cytology, Coculture Techniques, Genes, RAG-1, Glial Fibrillary Acidic Protein genetics, Gliosis genetics, Gliosis pathology, Graft Survival, Mice, Mice, Inbred C57BL, Mice, Knockout, Multipotent Stem Cells cytology, Oligodendroglia cytology, Rats, Vimentin genetics, Astrocytes cytology, Glial Fibrillary Acidic Protein deficiency, Hippocampus cytology, Multipotent Stem Cells transplantation, Neurons cytology, Vimentin deficiency
- Abstract
After neurotrauma, ischemia, or neurodegenerative disease, astrocytes upregulate their expression of the intermediate filament proteins glial fibrillary acidic protein (GFAP), vimentin (Vim), and nestin. This response, reactive gliosis, is attenuated in GFAP(-/-)Vim(-/-) mice, resulting in the promotion of synaptic regeneration after neurotrauma and improved integration of retinal grafts. Here we assessed whether GFAP(-/-)Vim(-/-) astrocytes affect the differentiation of neural progenitor cells. In coculture with GFAP(-/-)Vim(-/-) astrocytes, neural progenitor cells increased neurogenesis by 65% and astrogenesis by 124%. At 35 days after transplantation of neural progenitor cells into the hippocampus, adult GFAP(-/-)Vim(-/-) mice had more transplant-derived neurons and astrocytes than wild-type controls, as well as increased branching of neurite-like processes on transplanted cells. Wnt3 immunoreactivity was readily detected in hippocampal astrocytes in wild-type but not in GFAP(-/-)Vim(-/-) mice. These findings suggest that GFAP(-/-)Vim(-/-) astrocytes allow more neural progenitor cell-derived neurons and astrocytes to survive weeks after transplantation. Thus, reactive gliosis may adversely affect the integration of transplanted neural progenitor cells in the brain. Disclosure of potential conflicts of interest is found at the end of this article.
- Published
- 2007
- Full Text
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41. 14-3-3 expression in denervated hippocampus after entorhinal cortex lesion assessed by culture-derived isotope tags in quantitative proteomics.
- Author
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Sihlbom C, Wilhelmsson U, Li L, Nilsson CL, and Pekny M
- Subjects
- Animals, Astrocytes metabolism, Electrophoresis, Gel, Two-Dimensional, Entorhinal Cortex pathology, Glial Fibrillary Acidic Protein metabolism, Mass Spectrometry methods, Mice, Mice, Inbred C57BL, Mice, Transgenic, Neurodegenerative Diseases metabolism, Vimentin metabolism, 14-3-3 Proteins genetics, 14-3-3 Proteins physiology, Cerebral Cortex metabolism, Hippocampus metabolism, Proteomics methods
- Abstract
Activation of astrocytes accompanies many brain pathologies. Reactive astrocytes have a beneficial role in acute neurotrauma but later on might inhibit regeneration. 2D-gel electrophoresis and mass spectrometry were applied to study the proteome difference in denervated hippocampus in wildtype mice and mice lacking intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin (GFAP-/-Vim-/-) that show attenuated reactive gliosis and enhanced posttraumatic regeneration. Proteomic data and immunohistochemical analyses showed upregulation of the adapter protein 14-3-3 four days postlesion and suggested that 14-3-3 upregulation after injury is triggered by reactive gliosis. Culture-derived isotope tags (CDIT) and mass spectrometry demonstrated that 14-3-3 epsilon was the major isoform upregulated in denervated hippocampus and that its upregulation was attenuated in GFAP-/-Vim-/- mice and thus most likely connected to reactive gliosis.
- Published
- 2007
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- View/download PDF
42. Attenuated glial reactions and photoreceptor degeneration after retinal detachment in mice deficient in glial fibrillary acidic protein and vimentin.
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Nakazawa T, Takeda M, Lewis GP, Cho KS, Jiao J, Wilhelmsson U, Fisher SK, Pekny M, Chen DF, and Miller JW
- Subjects
- Animals, Blotting, Western, Chemokine CCL2 metabolism, Disease Models, Animal, Enzyme-Linked Immunosorbent Assay, Extracellular Signal-Regulated MAP Kinases metabolism, Fluorescent Antibody Technique, Indirect, Glial Fibrillary Acidic Protein deficiency, Gliosis etiology, Gliosis metabolism, Gliosis prevention & control, In Situ Nick-End Labeling, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Microglia physiology, Monocytes physiology, Photoreceptor Cells, Vertebrate pathology, Proto-Oncogene Proteins c-fos metabolism, Retinal Degeneration etiology, Retinal Degeneration metabolism, Reverse Transcriptase Polymerase Chain Reaction, Vimentin deficiency, Glial Fibrillary Acidic Protein physiology, Neuroglia physiology, Retina pathology, Retinal Degeneration prevention & control, Retinal Detachment complications, Vimentin physiology
- Abstract
Purpose: To characterize the reactions of retinal glial cells (astrocytes and Müller cells) to retinal injury in mice that lack glial fibrillary acidic protein (GFAP) and vimentin (GFAP-/-Vim-/-) and to determine the role of glial cells in retinal detachment (RD)-induced photoreceptor degeneration., Methods: RD was induced by subretinal injection of sodium hyaluronate in adult wild-type (WT) and GFAP-/-Vim-/- mice. Astroglial reaction and subsequent monocyte recruitment were quantified by measuring extracellular signal-regulated kinase (Erk) and c-fos activation and the level of expression of chemokine monocyte chemoattractant protein (MCP)-1 and by counting monocytes/microglia in the detached retinas. Immunohistochemistry, immunoblotting, real-time quantitative polymerase chain reaction (PCR), and enzyme-linked immunosorbent assay (ELISA) were used. RD-induced photoreceptor degeneration was assessed by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and measurement of outer nuclear layer (ONL) thickness., Results: RD-induced reactive gliosis, characterized by GFAP and vimentin upregulation, Erk and c-fos activation, MCP-1 induction, and increased monocyte recruitment in WT mice. Absence of GFAP and vimentin effectively attenuated reactive responses of retinal glial cells and monocyte infiltration. As a result, detached retinas of GFAP-/-Vim-/- mice exhibited significantly reduced numbers of TUNEL-positive photoreceptor cells and increased ONL thickness compared with those of WT mice., Conclusions: The absence of GFAP and vimentin attenuates RD-induced reactive gliosis and, subsequently, limits photoreceptor degeneration. Results of this study indicate that reactive retinal glial cells contribute critically to retinal damage induced by RD and provide a new avenue for limiting photoreceptor degeneration associated with RD and other retinal diseases or damage.
- Published
- 2007
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43. Synemin is expressed in reactive astrocytes in neurotrauma and interacts differentially with vimentin and GFAP intermediate filament networks.
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Jing R, Wilhelmsson U, Goodwill W, Li L, Pan Y, Pekny M, and Skalli O
- Subjects
- Animals, Cells, Cultured, Cloning, Molecular, DNA, Complementary, Glial Fibrillary Acidic Protein genetics, Humans, Intermediate Filament Proteins genetics, Mice, Mice, Knockout, RNA, Messenger metabolism, Vimentin genetics, Astrocytes metabolism, Entorhinal Cortex injuries, Glial Fibrillary Acidic Protein metabolism, Intermediate Filament Proteins metabolism, Intermediate Filaments metabolism, Vimentin metabolism
- Abstract
Immature astrocytes and astrocytoma cells contain synemin and three other intermediate filament (IF) proteins: glial fibrillary acidic protein (GFAP), vimentin and nestin. Here, we show that, after neurotrauma, reactive astrocytes produce synemin and thus propose synemin as a new marker of reactive astrocytes. Comparison of synemin mRNA and protein levels in brain tissues and astrocyte cultures from wild-type, Vim(-)(/)(-) and Gfap(-)(/)(-)Vim(-)(/)(-) mice showed that in the absence of vimentin, synemin protein was undetectable although synemin mRNA was present at wild-type levels. By contrast, in Gfap(-)(/)(-) astrocytes, synemin protein and mRNA levels, as well as synemin incorporation into vimentin IFs, were unaltered. Biochemical assays with purified proteins suggested that synemin interacts with GFAP IFs like an IF-associated protein rather than like a polymerization partner, whereas the opposite was true for synemin interaction with vimentin. In transfection experiments, synemin did not incorporate into normal, filamentous GFAP networks, but integrated into vimentin and GFAP heteropolymeric networks. Thus, alongside GFAP, vimentin and nestin, reactive astrocytes contain synemin, whose accumulation is suppressed post-transcriptionally in the absence of a polymerization partner. In astrocytes, this partner is vimentin and not GFAP, which implies a functional difference between these two type III IF proteins.
- Published
- 2007
- Full Text
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44. The role of astrocytes and complement system in neural plasticity.
- Author
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Pekny M, Wilhelmsson U, Bogestål YR, and Pekna M
- Subjects
- Animals, Glial Fibrillary Acidic Protein metabolism, Gliosis pathology, Humans, Intermediate Filaments metabolism, Trauma, Nervous System pathology, Astrocytes physiology, Complement System Proteins physiology, Neuronal Plasticity physiology
- Abstract
In neurotrauma, brain ischemia or neurodegenerative diseases, astrocytes become reactive (which is known as reactive gliosis) and this is accompanied by an altered expression of many genes. Two cellular hallmarks of reactive gliosis are hypertrophy of astrocyte processes and the upregulation of the part of the cytoskeleton known as intermediate filaments, which are composed of nestin, vimentin, and GFAP. Our aim has been to better understand the function of reactive astrocytes in CNS diseases. Using mice deficient for astrocyte intermediate filaments (GFAP(-/-)Vim(-/-)), we were able to attenuate reactive gliosis and slow down the healing process after neurotrauma. We demonstrated the key role of reactive astrocytes in neurotrauma-at an early stage after neurotrauma, reactive astrocytes have a neuroprotective effect; at a later stage, they facilitate the formation of posttraumatic glial scars and inhibit CNS regeneration, specifically, they seem to compromise neural graft survival and integration, reduce the extent of synaptic regeneration, inhibit neurogenesis in the old age, and inhibit regeneration of severed CNS axons. We propose that reactive astrocytes are the future target for the therapeutic strategies promoting regeneration and plasticity in the brain and spinal cord in various disease conditions. Through its involvement in inflammation, opsonization, and cytolysis, complement protects against infectious agents. Although most of the complement proteins are synthesized in CNS, the role of the complement system in the normal or ischemic CNS remains unclear. Complement activiation in the CNS has been generally considered as contributing to tissue damage. However, growing body of evidence suggests that complement may be a physiological neuroprotective mechanism as well as it may participate in maintenance and repair of the adult brain.
- Published
- 2007
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- View/download PDF
45. Redefining the concept of reactive astrocytes as cells that remain within their unique domains upon reaction to injury.
- Author
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Wilhelmsson U, Bushong EA, Price DL, Smarr BL, Phung V, Terada M, Ellisman MH, and Pekny M
- Subjects
- Animals, Cell Shape, Female, Mice, Astrocytes pathology, Brain Injuries pathology
- Abstract
Reactive astrocytes in neurotrauma, stroke, or neurodegeneration are thought to undergo cellular hypertrophy, based on their morphological appearance revealed by immunohistochemical detection of glial fibrillary acidic protein, vimentin, or nestin, all of them forming intermediate filaments, a part of the cytoskeleton. Here, we used a recently established dye-filling method to reveal the full three-dimensional shape of astrocytes assessing the morphology of reactive astrocytes in two neurotrauma models. Both in the denervated hippocampal region and the lesioned cerebral cortex, reactive astrocytes increased the thickness of their main cellular processes but did not extend to occupy a greater volume of tissue than nonreactive astrocytes. Despite this hypertrophy of glial fibrillary acidic protein-containing cellular processes, interdigitation between adjacent hippocampal astrocytes remained minimal. This work helps to redefine the century-old concept of hypertrophy of reactive astrocytes.
- Published
- 2006
- Full Text
- View/download PDF
46. Complement: a novel factor in basal and ischemia-induced neurogenesis.
- Author
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Rahpeymai Y, Hietala MA, Wilhelmsson U, Fotheringham A, Davies I, Nilsson AK, Zwirner J, Wetsel RA, Gerard C, Pekny M, and Pekna M
- Subjects
- Animals, Central Nervous System cytology, Central Nervous System metabolism, Complement Activation, Complement C3a genetics, Complement C5a genetics, Female, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Neurons metabolism, Receptor, Anaphylatoxin C5a genetics, Receptors, Complement antagonists & inhibitors, Receptors, Complement genetics, Stem Cells metabolism, Complement C3a physiology, Complement C5a physiology, Ischemia pathology, Neurons cytology, Receptor, Anaphylatoxin C5a metabolism, Receptors, Complement metabolism, Stem Cells cytology
- Abstract
Through its involvement in inflammation, opsonization, and cytolysis, the complement protects against infectious agents. Although most of the complement proteins are synthesized in the central nervous system (CNS), the role of the complement system in the normal or ischemic CNS remains unclear. Here we demonstrate for the first time that neural progenitor cells and immature neurons express receptors for complement fragments C3a and C5a (C3a receptor (C3aR) and C5a receptor). Mice that are deficient in complement factor C3 (C3(-/-)) lack C3a and are unable to generate C5a through proteolytic cleavage of C5 by C5-convertase. Intriguingly, basal neurogenesis is decreased both in C3(-/-) mice and in mice lacking C3aR or mice treated with a C3aR antagonist. The C3(-/-) mice had impaired ischemia-induced neurogenesis both in the subventricular zone, the main source of neural progenitor cells in adult brain, and in the ischemic region, despite normal proliferative response and larger infarct volumes. Thus, in the adult mammalian CNS, complement activation products promote both basal and ischemia-induced neurogenesis.
- Published
- 2006
- Full Text
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47. Increased cell proliferation and neurogenesis in the hippocampal dentate gyrus of old GFAP(-/-)Vim(-/-) mice.
- Author
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Larsson A, Wilhelmsson U, Pekna M, and Pekny M
- Subjects
- Animals, Antimetabolites, Bromodeoxyuridine, Cell Proliferation, Female, Immunohistochemistry, Mice, Mice, Inbred C57BL, Mice, Knockout, Microscopy, Confocal, Neurons physiology, Aging physiology, Dentate Gyrus cytology, Dentate Gyrus growth & development, Glial Fibrillary Acidic Protein genetics, Glial Fibrillary Acidic Protein physiology, Vimentin genetics, Vimentin physiology
- Abstract
In response to central nervous system (CNS) injury, and more discretely so also during aging, astrocytes become reactive and increase their expression of the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin. Studies of mice deficient in astrocytic intermediate filaments have provided insights into the function of reactive gliosis. Recently we demonstrated robust integration of retinal transplants (1) and increased posttraumatic synaptic regeneration (2) in GFAP(-/-)Vim(-/-) mice, suggesting that modulation of astrocyte activity affects the permissiveness of the CNS environment for regeneration. Neurogenesis in the adult mammalian CNS is restricted to essentially two regions, the hippocampus and the subventricular zone. Here, we assessed neurogenesis in the hippocampus of 18-month-old GFAP(-/-)Vim(-/-) mice. In the granular layer of the dentate gyrus, cell proliferation/survival was 34% higher and neurogenesis 36% higher in GFAP(-/-)Vim(-/-) mice than in wildtype controls. These findings suggest that the adult hippocampal neurogenesis in healthy old mice can be increased by modulating astrocyte reactivity.
- Published
- 2004
- Full Text
- View/download PDF
48. Absence of glial fibrillary acidic protein and vimentin prevents hypertrophy of astrocytic processes and improves post-traumatic regeneration.
- Author
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Wilhelmsson U, Li L, Pekna M, Berthold CH, Blom S, Eliasson C, Renner O, Bushong E, Ellisman M, Morgan TE, and Pekny M
- Subjects
- Animals, Astrocytes ultrastructure, Brain Injuries pathology, Cells, Cultured, Cytoplasm ultrastructure, Entorhinal Cortex injuries, Glutamate-Ammonia Ligase metabolism, Hypertrophy metabolism, Hypertrophy pathology, Hypertrophy prevention & control, Mice, Mice, Inbred C57BL, Receptor, Endothelin B metabolism, Up-Regulation, Astrocytes metabolism, Brain Injuries physiopathology, Glial Fibrillary Acidic Protein metabolism, Hippocampus metabolism, Hippocampus ultrastructure, Nerve Regeneration physiology, Vimentin metabolism
- Abstract
The regenerative capacity of the CNS is extremely limited. The reason for this is unclear, but glial cell involvement has been suspected, and oligodendrocytes have been implicated as inhibitors of neuroregeneration (Chen et al., 2000, GrandPre et al., 2000; Fournier et al., 2001). The role of astrocytes in this process was proposed but remains incompletely understood (Silver and Miller, 2004). Astrocyte activation (reactive gliosis) accompanies neurotrauma, stroke, neurodegenerative diseases, or tumors. Two prominent hallmarks of reactive gliosis are hypertrophy of astrocytic processes and upregulation of intermediate filaments. Using the entorhinal cortex lesion model in mice, we found that reactive astrocytes devoid of the intermediate filament proteins glial fibrillary acidic protein and vimentin (GFAP-/-Vim-/-), and consequently lacking intermediate filaments (Colucci-Guyon et al., 1994; Pekny et al., 1995; Eliasson et al., 1999), showed only a limited hypertrophy of cell processes. Instead, many processes were shorter and not straight, albeit the volume of neuropil reached by a single astrocyte was the same as in wild-type mice. This was accompanied by remarkable synaptic regeneration in the hippocampus. On a molecular level, GFAP-/-Vim-/- reactive astrocytes could not upregulate endothelin B receptors, suggesting that the upregulation is intermediate filament dependent. These findings show a novel role for intermediate filaments in astrocytes and implicate reactive astrocytes as potent inhibitors of neuroregeneration.
- Published
- 2004
- Full Text
- View/download PDF
49. Response to Quinlan and Nilsson: Astroglia sitting at the controls?
- Author
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Pekny M, Pekna M, Wilhelmsson U, and Chen DF
- Subjects
- Animals, Disease Models, Animal, Humans, Mice, Mice, Transgenic, Nerve Regeneration physiology, Astrocytes physiology, Neurodegenerative Diseases therapy
- Published
- 2004
- Full Text
- View/download PDF
50. Robust neural integration from retinal transplants in mice deficient in GFAP and vimentin.
- Author
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Kinouchi R, Takeda M, Yang L, Wilhelmsson U, Lundkvist A, Pekny M, and Chen DF
- Subjects
- Animals, Cell Movement, Mice, Mice, Knockout, Retina pathology, Retina physiopathology, Glial Fibrillary Acidic Protein deficiency, Neurons physiology, Neurons transplantation, Retina surgery, Vimentin deficiency
- Abstract
With recent progress in neuroscience and stem-cell research, neural transplantation has emerged as a promising therapy for treating CNS diseases. The success of transplantation has been limited, however, by the restricted ability of neural implants to survive and establish neuronal connections with the host. Little is known about the mechanisms responsible for this failure. Neural implantation triggers reactive gliosis, a process accompanied by upregulation of intermediate filaments in astrocytes and formation of astroglial scar tissue. Here we show that the retinas of adult mice deficient in glial fibrillary acidic protein and vimentin, and consequently lacking intermediate filaments in reactive astrocytes and Müller cells, provide a permissive environment for grafted neurons to migrate and extend neurites. The transplanted cells integrated robustly into the host retina with distinct neuronal identity and appropriate neuronal projections. Our results indicate an essential role for reactive astroglial cells in preventing neural graft integration after transplantation.
- Published
- 2003
- Full Text
- View/download PDF
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