15 results on '"S Grossmann"'
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2. A genetically defined asymmetry underlies the inhibitory control of flexor–extensor locomotor movements
- Author
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Katja S. Grossmann, Jason R.B. Dyck, Simon Gosgnach, Olivier Britz, Susan M. Dymecki, Jun Chul Kim, Jingming Zhang, and Martyn Goulding
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QH301-705.5 ,mouse genetic ,Science ,Motor behavior ,Hindlimb ,Biology ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,0302 clinical medicine ,Inhibitory control ,medicine ,Motor activity ,Biology (General) ,mouse ,030304 developmental biology ,0303 health sciences ,General Immunology and Microbiology ,Stance phase ,General Neuroscience ,spinal interneurons ,General Medicine ,Anatomy ,motor behavior ,musculoskeletal system ,Spinal cord ,mouse genetics ,locomotion ,body regions ,medicine.anatomical_structure ,Medicine ,Neuroscience ,030217 neurology & neurosurgery ,Research Article - Abstract
V1 and V2b interneurons (INs) are essential for the production of an alternating flexor–extensor motor output. Using a tripartite genetic system to selectively ablate either V1 or V2b INs in the caudal spinal cord and assess their specific functions in awake behaving animals, we find that V1 and V2b INs function in an opposing manner to control flexor–extensor-driven movements. Ablation of V1 INs results in limb hyperflexion, suggesting that V1 IN-derived inhibition is needed for proper extension movements of the limb. The loss of V2b INs results in hindlimb hyperextension and a delay in the transition from stance phase to swing phase, demonstrating V2b INs are required for the timely initiation and execution of limb flexion movements. Our findings also reveal a bias in the innervation of flexor- and extensor-related motor neurons by V1 and V2b INs that likely contributes to their differential actions on flexion–extension movements. DOI: http://dx.doi.org/10.7554/eLife.04718.001, eLife digest Although there are many different movements an animal can make with its limbs—from reaching to walking—they all basically involve two sets of muscles that act as opposing levers around each joint. ‘Flexor’ muscles contract to bend the limb, and ‘extensor’ muscles contract to extend the limb. When an animal is walking these two sets of muscles contract repeatedly, one after the other. Inhibitory neurons in the spinal cord coordinate these walking movements by preventing the flexor or extensor muscles from contracting at the same time. In 2014, researchers discovered that two groups of inhibitory neurons, known as the V1 and V2b interneurons, are essential for this alternating pattern of flexing and extending of the limbs of newborn mice. However, these experiments were not able to assess the particular contribution that the V1 and V2b neurons each make to limb movements. Now, Britz et al.—including several of the researchers involved in the 2014 study—have used a sophisticated genetic technique in mice to investigate the role that each group of neurons plays separately. This involved introducing a gene into either the V1 or V2b neurons that makes them susceptible to being killed with the diphtheria toxin. Injecting the mice with diphtheria toxin selectively removed these cells from the regions of the spinal cord that controls hindlimb movements. Britz et al. found that removing either group of neurons prevented the mice from walking normally. Eliminating the V1 neurons caused extreme flexing of the hindlimbs, revealing that the V1 neurons are needed to extend the limb by inhibiting the motor neurons that contract the flexor muscles. In contrast, the loss of V2b neurons caused exaggerated hindlimb extension, indicating that the V2b neurons inhibit the motor neurons that innervate extensor muscles. Both the V1 and V2b groups of neurons contain a wide range of different cell types. Future studies will therefore need to explore how these different cells are involved in coordinating the motions involved in walking. DOI: http://dx.doi.org/10.7554/eLife.04718.002
- Published
- 2015
3. Mutant Desmocollin-2 Causes Arrhythmogenic Right Ventricular Cardiomyopathy
- Author
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Craig T. Basson, Patrick T. Ellinor, Jordan T. Shin, Eva Plovie, Sabine Sasse-Klaassen, Brenda Gerull, Calum A. MacRae, Arnd Heuser, Thomas Wichter, Ludwig Thierfelder, Bruce B. Lerman, and Katja S. Grossmann
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Adult ,Cardiac function curve ,medicine.medical_specialty ,Pathology ,Embryo, Nonmammalian ,Molecular Sequence Data ,Plakoglobin ,Biology ,Right ventricular cardiomyopathy ,Sudden cardiac death ,Desmosome ,Report ,Internal medicine ,medicine ,Genetics ,Animals ,Humans ,Genetics(clinical) ,Amino Acid Sequence ,Arrhythmogenic Right Ventricular Dysplasia ,Zebrafish ,Genetics (clinical) ,Desmocollins ,DSC2 ,Base Sequence ,Heart ,Middle Aged ,medicine.disease ,Myocardial Contraction ,Arrhythmogenic right ventricular dysplasia ,Endocrinology ,medicine.anatomical_structure ,Mutation ,Desmocollin - Abstract
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically heterogeneous heart-muscle disorder characterized by progressive fibrofatty replacement of right ventricular myocardium and an increased risk of sudden cardiac death. Mutations in desmosomal proteins that cause ARVC have been previously described; therefore, we investigated 88 unrelated patients with the disorder for mutations in human desmosomal cadherin desmocollin-2 (DSC2). We identified a heterozygous splice-acceptor-site mutation in intron 5 (c.631-2A--G) of the DSC2 gene, which led to the use of a cryptic splice-acceptor site and the creation of a downstream premature termination codon. Quantitative analysis of cardiac DSC2 expression in patient specimens revealed a marked reduction in the abundance of the mutant transcript. Morpholino knockdown in zebrafish embryos revealed a requirement for dsc2 in the establishment of the normal myocardial structure and function, with reduced desmosomal plaque area, loss of the desmosome extracellular electron-dense midlines, and associated myocardial contractility defects. These data identify DSC2 mutations as a cause of ARVC in humans and demonstrate that physiologic levels of DSC2 are crucial for normal cardiac desmosome formation, early cardiac morphogenesis, and cardiac function.
- Published
- 2006
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4. Tyrosine kinase receptor RON functions downstream of the erythropoietin receptor to induce expansion of erythroid progenitors
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Emile van den Akker, Ute Schaeper, Kenya Toney-Earley, Marieke von Lindern, Katja S. Grossmann, Thamar B. van Dijk, Susan E. Waltz, Martine Parren-van Amelsvoort, Bob Löwenberg, Hematology, and Landsteiner Laboratory
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Immunology ,GAB2 ,Biology ,Biochemistry ,Receptor tyrosine kinase ,Cell Line ,Hemoglobins ,hemic and lymphatic diseases ,Proto-Oncogene Proteins ,Chlorocebus aethiops ,Receptors, Erythropoietin ,Animals ,Humans ,Phosphorylation ,Protein kinase A ,Phosphotyrosine ,Protein kinase B ,Erythropoietin ,Adaptor Proteins, Signal Transducing ,Receptor Protein-Tyrosine Kinases ,Cell Differentiation ,Cell Biology ,Hematology ,Janus Kinase 2 ,Protein-Tyrosine Kinases ,Hematopoietic Stem Cells ,Phosphoproteins ,Erythropoietin receptor ,Cancer research ,biology.protein ,Rabbits ,Signal transduction ,Proto-oncogene tyrosine-protein kinase Src - Abstract
Erythropoietin (EPO) is required for cell survival during differentiation and for progenitor expansion during stress erythropoiesis. Although signaling pathways may couple directly to docking sites on the EPO receptor (EpoR), additional docking molecules expand the signaling platform of the receptor. We studied the roles of the docking molecules Grb2-associated binder-1 (Gab1) and Gab2 in EPO-induced signal transduction and erythropoiesis. Inhibitors of phosphatidylinositide 3-kinase and Src kinases suppressed EPO-dependent phosphorylation of Gab2. In contrast, Gab1 activation depends on recruitment and phosphorylation by the tyrosine kinase receptor RON, with which it is constitutively associated. RON activation induces the phosphorylation of Gab1, mitogen-activated protein kinase (MAPK), and protein kinase B (PKB) but not of signal transducer and activator of transcription 5 (Stat5). RON activation was sufficient to replace EPO in progenitor expansion but not in differentiation. In conclusion, we elucidated a novel mechanism specifically involved in the expansion of erythroblasts involving RON as a downstream target of the EpoR. (Blood. 2004;103:4457-4465)
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- 2004
5. Identification of a spinal circuit for light touch and fine motor control
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Martyn Goulding, Lidia Garcia-Campmany, Katja S. Grossmann, Steeve Bourane, Marta Garcia Del Barrio, Floor J. Stam, Stephanie C. Koch, Antoine Dalet, and Olivier Britz
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Cerebellum ,Spinal Cord Dorsal Horn ,Population ,Sensory system ,Biology ,Motor Activity ,Mechanotransduction, Cellular ,General Biochemistry, Genetics and Molecular Biology ,Article ,Mice ,Stimulus modality ,Interneurons ,Sensation ,Neural Pathways ,medicine ,Animals ,education ,Motor Neurons ,education.field_of_study ,Biochemistry, Genetics and Molecular Biology(all) ,Nuclear Receptor Subfamily 1, Group F, Member 1 ,Anatomy ,Spinal cord ,medicine.anatomical_structure ,Touch ,Synapses ,Reflex ,Neuroscience - Abstract
SummarySensory circuits in the dorsal spinal cord integrate and transmit multiple cutaneous sensory modalities including the sense of light touch. Here, we identify a population of excitatory interneurons (INs) in the dorsal horn that are important for transmitting innocuous light touch sensation. These neurons express the ROR alpha (RORα) nuclear orphan receptor and are selectively innervated by cutaneous low threshold mechanoreceptors (LTMs). Targeted removal of RORα INs in the dorsal spinal cord leads to a marked reduction in behavioral responsiveness to light touch without affecting responses to noxious and itch stimuli. RORα IN-deficient mice also display a selective deficit in corrective foot movements. This phenotype, together with our demonstration that the RORα INs are innervated by corticospinal and vestibulospinal projection neurons, argues that the RORα INs direct corrective reflex movements by integrating touch information with descending motor commands from the cortex and cerebellum.
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- 2014
6. Shp2/MAPK signaling controls goblet/paneth cell fate decisions in the intestine
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Walter Birchmeier, Katja S. Grossmann, Julian Heuberger, Jingjing Qi, Klaus Rajewsky, and Frauke Kosel
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Cancer Research ,Paneth Cells ,Blotting, Western ,Protein Tyrosine Phosphatase, Non-Receptor Type 11 ,Biology ,digestive system ,HT29 Cells ,Mice ,Organ Culture Techniques ,medicine ,Animals ,Humans ,Immunoprecipitation ,Progenitor cell ,Intestinal Mucosa ,Wnt Signaling Pathway ,beta Catenin ,Mitogen-Activated Protein Kinase Kinases ,Goblet cell ,Multidisciplinary ,Stem Cells ,Wnt signaling pathway ,LGR5 ,Cell Differentiation ,Biological Sciences ,Intestinal epithelium ,Cell biology ,medicine.anatomical_structure ,Paneth cell ,Goblet Cells ,Stem cell - Abstract
In the development of the mammalian intestine, Notch and Wnt/{beta}-catenin signals control stem cell maintenance and their differentiation into absorptive and secretory cells. Mechanisms that regulate differentiation of progenitors into the three secretory lineages, goblet, paneth, or enteroendocrine cells, are not fully understood. Using conditional mutagenesis in mice, we observed that Shp2-mediated MAPK signaling determines the choice between paneth and goblet cell fates and also affects stem cells, which express the leucine-rich repeat-containing receptor 5 (Lgr5). Ablation of the tyrosine phosphatase Shp2 in the intestinal epithelium reduced MAPK signaling and led to a reduction of goblet cells while promoting paneth cell development. Conversely, conditional mitogen-activated protein kinase kinase 1 (Mek1) activation rescued the Shp2 phenotype, promoted goblet cell and inhibited paneth cell generation. The Shp2 mutation also expanded Lgr5+ stem cell niches, which could be restricted by activated Mek1 signaling. Changes of Lgr5+ stem cell quantities were accompanied by alterations of paneth cells, indicating that Shp2/MAPK signaling might affect stem cell niches directly or via paneth cells. Remarkably, inhibition of MAPK signaling in intestinal organoids and cultured cells changed the relative abundance of Tcf4 isoforms and by this, promoted Wnt/{beta}-catenin activity. The data thus show that Shp2-mediated MAPK signaling controls the choice between goblet and paneth cell fates by regulating Wnt/{beta}-catenin activity.
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- 2014
7. A transcription factor code defines nine sensory interneuron subtypes in the mechanosensory area of the spinal cord
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Katja S. Grossmann, Dennis D.M. O'Leary, Roland Schüle, Steeve Bourane, Martyn Goulding, Marta Garcia Del Barrio, Stefan Britsch, and MDC Library
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Sensory Receptor Cells ,Interneuron ,lcsh:Medicine ,Mice, Transgenic ,570 Life Sciences ,Sensory system ,Biology ,Somatosensory system ,Mechanotransduction, Cellular ,610 Medical Sciences, Medicine ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Interneurons ,Cutaneous receptor ,medicine ,Animals ,lcsh:Science ,030304 developmental biology ,0303 health sciences ,Multidisciplinary ,lcsh:R ,Anatomy ,Spinal cord ,Posterior Horn Cells ,medicine.anatomical_structure ,Nociception ,Spinal Cord ,nervous system ,GDF7 ,Cellular Mechanotransduction ,lcsh:Q ,Transcriptome ,Function and Dysfunction of the Nervous System ,Neuroscience ,030217 neurology & neurosurgery ,Research Article ,Transcription Factors - Abstract
Interneurons in the dorsal spinal cord process and relay innocuous and nociceptive somatosensory information from cutaneous receptors that sense touch, temperature and pain. These neurons display a well-defined organization with respect to their afferent innervation. Nociceptive afferents innervate lamina I and II, while cutaneous mechanosensory afferents primarily innervate sensory interneurons that are located in lamina III–IV. In this study, we outline a combinatorial transcription factor code that defines nine different inhibitory and excitatory interneuron populations in laminae III–IV of the postnatal cord. This transcription factor code reveals a high degree of molecular diversity in the neurons that make up laminae III–IV, and it lays the foundation for systematically analyzing and manipulating these different neuronal populations to assess their function. In addition, we find that many of the transcription factors that are expressed in the dorsal spinal cord at early postnatal times continue to be expressed in the adult, raising questions about their function in mature neurons and opening the door to their genetic manipulation in adult animals.
- Published
- 2013
8. The tyrosine phosphatase Shp2 acts downstream of GDNF/Ret in branching morphogenesis of the developing mouse kidney
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Kai M. Schmidt-Ott, Frank Costantini, Walter Birchmeier, Odyssé Michos, Katharina Walentin, Katja S. Grossmann, Regina Willecke, and Julian Heuberger
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Male ,medicine.medical_specialty ,Ubiquitin-Protein Ligases ,Mutant ,Kidney development ,Protein Tyrosine Phosphatase, Non-Receptor Type 11 ,Protein tyrosine phosphatase ,Kidney ,Receptor tyrosine kinase ,Mice ,Downregulation and upregulation ,Internal medicine ,medicine ,Glial cell line-derived neurotrophic factor ,Morphogenesis ,Animals ,Wolffian duct ,Glial Cell Line-Derived Neurotrophic Factor ,Molecular Biology ,Adaptor Proteins, Signal Transducing ,Cell Proliferation ,Homeodomain Proteins ,Mice, Knockout ,biology ,urogenital system ,Kidney metabolism ,Membrane Proteins ,Nuclear Proteins ,Cell Biology ,Phosphoproteins ,Cell biology ,Erk/MAPK ,DNA-Binding Proteins ,Sprouty1 ,Endocrinology ,Ureteric bud ,Mutation ,biology.protein ,Female ,Developmental Biology ,Signal Transduction - Abstract
The tyrosine phosphatase Shp2 acts downstream of various growth factors, hormones or cytokine receptors. Mutations of the Shp2 gene are associated with several human diseases. Here we have ablated Shp2 in the developing kidneys of mice, using the ureteric bud epithelium-specific Hoxb7/Cre. Mutant mice produced a phenotype that is similar to mutations of the genes of the GDNF/Ret receptor system, that is: strongly reduced ureteric bud branching and downregulation of the Ret target genes Etv4 and Etv5. Shp2 mutant embryonic kidneys also displayed reduced cell proliferation at the branch tips and branching defects, which could not be overcome by GDNF in organ culture. We also examined compound mutants of Shp2 and Sprouty1, which is an inhibitor of receptor tyrosine kinase signaling in the kidney. Sprouty1 single mutants produce supernumerary ureteric buds, which branch excessively. Sprouty1 mutants rescued branching deficits in Ret−/− and GDNF−/− kidneys. Sprouty1; Shp2 double mutants showed no rescue of kidney branching. Our data thus indicate an intricate interplay of Shp2 and Sprouty1 in signaling downstream of receptor tyrosine kinases during kidney development. Apparently, Shp2 mediates not only GDNF/Ret but also signaling by other receptor tyrosine kinases in branching morphogenesis of the embryonic kidney.
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- 2011
9. Genetic Dissection of Rhythmic Motor Networks in Mice
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Aurore Giraudin, Martyn Goulding, Katja S. Grossmann, Jingming Zhang, and Olivier Britz
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Nervous system ,Periodicity ,Interneuron ,Nerve net ,Stem Cells ,Central pattern generator ,Brain ,Hindbrain ,Cell Differentiation ,Biology ,Spinal cord ,Article ,Mice ,medicine.anatomical_structure ,Rhythm ,CpG site ,Spinal Cord ,Interneurons ,medicine ,Animals ,Nerve Net ,Neuroscience ,Locomotion ,Transcription Factors - Abstract
Simple motor behaviors such as locomotion and respiration involve rhythmic and coordinated muscle movements that are generated by central pattern generator (CPG) networks in the spinal cord and hindbrain. These CPG networks produce measurable behavioral outputs, and thus represent ideal model systems for studying the operational principles that the nervous system uses to produce specific behaviors. Recent advances in our understanding of the transcriptional code that controls neuronal development have provided an entry point into identifying and targeting distinct neuronal populations that make up locomotor CPG networks in the spinal cord. This has spurred the development of new genetic approaches to dissect and manipulate neuronal networks both in the spinal cord and hindbrain. Here we discuss how the advent of molecular genetics together with anatomical and physiological methods has begun to revolutionize studies of the neuronal networks controlling rhythmic motor behaviors in mice.
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- 2010
10. The Tyrosine Phosphatase Shp2 in Development and Cancer
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Marta Rosário, Katja S. Grossmann, Carmen Birchmeier, and Walter Birchmeier
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Genetics ,Mutation ,biology ,Juvenile myelomonocytic leukemia ,Protein tyrosine phosphatase ,medicine.disease_cause ,medicine.disease ,LEOPARD Syndrome ,Receptor tyrosine kinase ,PTPN11 ,Germline mutation ,biology.protein ,medicine ,Carcinogenesis - Abstract
Deregulation of signaling pathways, through mutation or other molecular changes, can ultimately result in disease. The tyrosine phosphatase Shp2 has emerged as a major regulator of receptor tyrosine kinase (RTK) and cytokine receptor signaling. In the last decade, germline mutations in the human PTPN11 gene, encoding Shp2, were linked to Noonan (NS) and LEOPARD syndromes, two multisymptomatic developmental disorders that are characterized by short stature, craniofacial defects, cardiac defects, and mental retardation. Somatic Shp2 mutations are also associated with several types of human malignancies, such as the most common juvenile leukemia, juvenile myelomonocytic leukemia (JMML). Whereas NS and JMML are caused by gain-of-function (GOF) mutations of Shp2, loss-of-function (LOF) mutations are thought to be associated with LEOPARD syndrome. Animal models that carry conditional LOF and GOF mutations have allowed a better understanding of the mechanism of Shp2 function in disease, and shed light on the role of Shp2 in signaling pathways that control decisive events during embryonic development or during cellular transformation/tumorigenesis.
- Published
- 2010
11. The tyrosine phosphatase Shp2 (PTPN11) directs Neuregulin-1/ErbB signaling throughout Schwann cell development
- Author
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Sandra Zurborg, Hagen Wende, Florian E. Paul, Alistair N. Garratt, Herbert Schulz, Walter Birchmeier, Daniel Besser, Elior Peles, Katja S. Grossmann, Matthias Selbach, Konstantin Feinberg, Carmen Birchmeier, and Cyril Cheret
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Neuregulin-1 ,Schwann cell ,Fluorescent Antibody Technique ,Protein Tyrosine Phosphatase, Non-Receptor Type 11 ,Receptor tyrosine kinase ,Mice ,ErbB ,mental disorders ,medicine ,Animals ,Neuregulin 1 ,Multidisciplinary ,biology ,Biological Sciences ,Cell biology ,ErbB Receptors ,medicine.anatomical_structure ,Neural Crest ,Cancer research ,biology.protein ,Neuregulin ,Schwann Cells ,Signal transduction ,Tyrosine kinase ,Proto-oncogene tyrosine-protein kinase Src ,Signal Transduction - Abstract
The nonreceptor tyrosine phosphatase Shp2 (PTPN11) has been implicated in tyrosine kinase, cytokine, and integrin receptor signaling. We show here that conditional mutation of Shp2 in neural crest cells and in myelinating Schwann cells resulted in deficits in glial development that are remarkably similar to those observed in mice mutant for Neuregulin-1 (Nrg1) or the Nrg1 receptors, ErbB2 and ErbB3. In cultured Shp2 mutant Schwann cells, Nrg1-evoked cellular responses like proliferation and migration were virtually abolished, and Nrg1-dependent intracellular signaling was altered. Pharmacological inhibition of Src family kinases mimicked all cellular and biochemical effects of the Shp2 mutation, implicating Src as a primary Shp2 target during Nrg1 signaling. Together, our genetic and biochemical analyses demonstrate that Shp2 is an essential component in the transduction of Nrg1/ErbB signals.
- Published
- 2009
12. mpact of Arenicola marina on bacteria in intertidal sediments
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W. Reichardt and S. Grossmann
- Subjects
Ecology ,biology ,Intertidal sediments ,Environmental science ,Arenicola ,Aquatic Science ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Bacteria - Published
- 1991
13. Requirement of plakophilin 2 for heart morphogenesis and cardiac junction formation
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Martin Behrend, Christine Grund, Werner W. Franke, Walter Birchmeier, Joerg Huelsken, Katja S. Grossmann, and Bettina Erdmann
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Heart morphogenesis ,Cancer Research ,Alleles ,Animals ,Blotting, Western ,Crosses, Genetic ,Detergents/pharmacology ,Gene Expression Regulation, Developmental ,Genetic Vectors ,Heart/embryology ,Heart/physiology ,Immunohistochemistry ,Mice ,Mice, Transgenic ,Microscopy, Fluorescence ,Microscopy, Immunoelectron ,Models, Genetic ,Mutation ,Octoxynol/pharmacology ,Phenotype ,Plakophilins ,Proteins/genetics ,Proteins/physiology ,Time Factors ,Octoxynol ,Detergents ,Morphogenesis ,Biology ,Plakophilin ,Article ,Cytoskeleton ,Research Articles ,Heart development ,Desmoplakin ,Proteins ,Heart ,Cell Biology ,Cell biology ,Cytoplasm ,embryonic structures ,biology.protein ,Technology Platforms - Abstract
Plakophilins are proteins of the armadillo family that function in embryonic development and in the adult, and when mutated can cause disease. We have ablated the plakophilin 2 gene in mice. The resulting mutant mice exhibit lethal alterations in heart morphogenesis and stability at mid-gestation (E10.5–E11), characterized by reduced trabeculation, disarrayed cytoskeleton, ruptures of cardiac walls, and blood leakage into the pericardiac cavity. In the absence of plakophilin 2, the cytoskeletal linker protein desmoplakin dissociates from the plaques of the adhering junctions that connect the cardiomyocytes and forms granular aggregates in the cytoplasm. By contrast, embryonic epithelia show normal junctions. Thus, we conclude that plakophilin 2 is important for the assembly of junctional proteins and represents an essential morphogenic factor and architectural component of the heart.
- Published
- 2004
14. Mutations in the desmosomal protein plakophilin-2 are common in arrhythmogenic right ventricular cardiomyopathy
- Author
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Calum A. MacRae, Beate Michely, Katja S. Grossmann, Thomas Wichter, Craig T. Basson, Matthias Paul, Deborah A. McDermott, Walter Birchmeier, Günter Breithardt, Stefan Peters, Rainer Dietz, Bruce B. Lerman, Patrick T. Ellinor, Ludwig Thierfelder, Eric Schulze-Bahr, Sabine Sasse-Klaassen, Arnd Heuser, Brenda Gerull, and Steve M Markowitz
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Male ,medicine.medical_specialty ,Adolescent ,Molecular Sequence Data ,Desmoglein-2 ,Plakoglobin ,Sudden death ,Right ventricular cardiomyopathy ,Sudden cardiac death ,Internal medicine ,Genetics ,medicine ,Humans ,Arrhythmogenic Right Ventricular Dysplasia ,DSC2 ,biology ,Desmoplakin ,Proteins ,Desmosomes ,medicine.disease ,Arrhythmogenic right ventricular dysplasia ,Endocrinology ,Mutation ,cardiovascular system ,biology.protein ,Cardiology ,Female ,Plakophilins - Abstract
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with fibrofatty replacement of cardiac myocytes, ventricular tachyarrhythmias and sudden cardiac death. In 32 of 120 unrelated individuals with ARVC, we identified heterozygous mutations in PKP2, which encodes plakophilin-2, an essential armadillo-repeat protein of the cardiac desmosome. In two kindreds with ARVC, disease was incompletely penetrant in most carriers of PKP2 mutations.
- Published
- 2004
15. Bacterial activity in sea ice and open water of the Weddell Sea, Antarctica: A microautoradiographic study
- Author
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S. Grossmann
- Subjects
0106 biological sciences ,0303 health sciences ,Biomass (ecology) ,geography ,geography.geographical_feature_category ,Ecology ,030306 microbiology ,010604 marine biology & hydrobiology ,Soil Science ,Biology ,biology.organism_classification ,01 natural sciences ,Algal bloom ,Arctic ice pack ,03 medical and health sciences ,Water column ,Environmental chemistry ,Phytoplankton ,Sea ice ,Photic zone ,14. Life underwater ,Ecology, Evolution, Behavior and Systematics ,Bacteria - Abstract
Metabolic activity of bacteria was investigated in open water, newly forming sea ice, and successive stages of pack ice in the Weddell Sea. Microautoradiography, using [(3)H]leucine as substrate, was compared with incorporation rates of [(3)H]leucine into proteins. Relation of [(3)H]leucine incorporation to the biomass of active bacteria provides information about changes of specific metabolic activity of cells. During a phytoplankton bloom in an ice-free, stratified water column, total numbers of bacteria in the euphotic zone averaged 2.3 × 10(5) ml(-1), but only about 13% showed activity via leucine uptake. Growth rate of the active bacteria was estimated as 0.3-0.4 days(-1). Total cell concentration of bacteria in 400 m depth was 6.6 × 10(4) ml(-1). Nearly 50% of these cells were active, although biomass production and specific growth rate were only about one-tenth that of the surface populations. When sea ice was forming in high concentrations of phytoplankton, bacterial biomass in the newly formed ice was 49.1 ng C ml(-1), exceeding that in open water by about one order of magnitude. Attachment of large bacteria to algal cells seems to cause their enrichment in the new ice, since specific bacterial activity was reduced during ice formation, and enrichment of bacteria was not observed when ice formed at low algal concentration. During growth of pack ice, biomass of bacteria increased within the brine channel system. Specific activity was still reduced at these later stages of ice development, and percentages of active cells were as low as 3-5%. In old, thick pack ice, bacterial activity was high and about 30% of cells were active. However, biomass-specific activity of bacteria remained significantly lower than that in open water. It is concluded that bacterial assemblages different to those of open water developed within the ice and were dominated by bacteria with lower average metabolic activity than those of ice-free water.
- Published
- 1993
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