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UV-induced toxicity is characterized by marked oxidative stress, accompanied by the depletion of key cellular antioxidants, particularly glutathione ( GSH). Replenishing cellular GSH may represent a means of counteracting UV-induced toxicity: however, treatment with free GSH is not therapeutically effective due to its unfavorable pharmacokinetic properties. In this study, we show that S-acyl-glutathione (acyl- SG) derivatives, which consist of an acyl chain (of variable length and saturation) linked via a thioester bond to GSH, increase intracellular levels of reduced GSH in primary skin fibroblasts, adenocarcinoma HeLa and neuroblastoma SH- SY5Y cells. Consistent with this, acyl- SG derivatives protect against UV-induced reactive oxygen species ( ROS) production and UV-B/C-mediated lipid peroxidation and caspase-3 activation in the analyzed cell lines, with unsaturated thioesters displaying a significantly greater protective effect. Taken together, our findings suggest that acyl- SG thioesters may be therapeutically effective in the treatment of UV-related skin disorders and oxidative stress-mediated conditions in general. [ABSTRACT FROM AUTHOR]

Cell therapy is a promising approach for the treatment of neurodegenerative conditions such as Alzheimer's and Parkinson's diseases. However, the presence of toxic aggregates in tissue raises the question of whether grafted stem cells are susceptible to amyloid toxicity before they differentiate into mature neurons. To address this question, we investigated the relative vulnerability of human mesenchymal stromal cells and their neuronally differentiated counterparts to Aβ42 oligomers and whether susceptibility correlates with membrane GM1 content, a key player in oligomer toxicity. We found that our cell model was highly susceptible to aggregate toxicity, whereas neuronal differentiation induced resistance to amyloid species. This data correlated well with the content of membrane GM1, levels of which decreased considerably in differentiated cells. These findings extend our knowledge of stem cell vulnerability to amyloid species, which remains a controversial issue, and confirm that amyloid-GM1 interactions play an important role in cell impairment. [ABSTRACT FROM AUTHOR]

Investigates the biochemical features of cell death upon exposure to hydrogenase maturation factor HypF-N toxic prefibrillar aggregates. Caspase activation during H-END and NIH/3T3 cell death; Role of Bid and mitochondria involvement; Up-regulation of the expression of the corresponding gene after p53 activation.

Transient oligomeric species formed during the aggregation process of the 42-residue form of the amyloid-β peptide (Aβ42) are key pathogenic agents in Alzheimer's disease (AD). To investigate the relationship between Aβ42 aggregation and its cytotoxicity and the influence of a potential drug on both phenomena, we have studied the effects of trodusquemine. This aminosterol enhances the rate of aggregation by promoting monomer-dependent secondary nucleation, but significantly reduces the toxicity of the resulting oligomers to neuroblastoma cells by inhibiting their binding to the cellular membranes. When administered to a C. elegans model of AD, we again observe an increase in aggregate formation alongside the suppression of Aβ42-induced toxicity. In addition to oligomer displacement, the reduced toxicity could also point towards an increased rate of conversion of oligomers to less toxic fibrils. The ability of a small molecule to reduce the toxicity of oligomeric species represents a potential therapeutic strategy against AD. Transient oligomeric species of the amyloid-β peptide (Aβ42) have been identified as key pathogenic agents in Alzheimer's disease. Here the authors find that the aminosterol trodusquemine enhances Aβ42 aggregation and suppresses Aβ42-induced toxicity by displacing oligomers from cell membranes. [ABSTRACT FROM AUTHOR]

This document summarizes two studies related to Alzheimer's disease (AD). The first study, called PRAMA, conducted in Italy, analyzed cerebrospinal fluid (CSF) samples to identify biomarkers for AD. The researchers found that AD cases had higher levels of certain protein species and misfolded proteins in the CSF, suggesting that the entire proteome in the CSF may be important for assessing AD. The second study explores the relationship between genetic factors and AD, emphasizing the role of genetic testing in identifying individuals at risk. The report discusses specific genes, such as APOE, and their impact on susceptibility to AD. It also examines the potential of genetic therapies and personalized medicine in preventing and treating the disease. The report provides a comprehensive overview of current research in the field and is valuable for individuals and healthcare professionals interested in understanding the genetic basis of AD. [Extracted from the article]

Background: Amyloid-β42 (Aβ42) aggregation consists of a complex chain of nucleation events producing soluble oligomeric intermediates, which are considered the major neurotoxic agents in Alzheimer's disease (AD). Cerebral lesions in the brain of AD patients start to develop 20 years before symptom onset; however, no preventive strategies, effective treatments, or specific and sensitive diagnostic tests to identify people with early-stage AD are currently available. In addition, the isolation and characterisation of neurotoxic Aβ42 oligomers are particularly difficult because of their transient and heterogeneous nature. To overcome this challenge, a rationally designed method generated a single-domain antibody (sdAb), named DesAb-O, targeting Aβ42 oligomers. Methods: We investigated the ability of DesAb-O to selectively detect preformed Aβ42 oligomers both in vitro and in cultured neuronal cells, by using dot-blot, ELISA immunoassay and super-resolution STED microscopy, and to counteract the toxicity induced by the oligomers, monitoring their interaction with neuronal membrane and the resulting mitochondrial impairment. We then applied this approach to CSF samples (CSFs) from AD patients as compared to age-matched control subjects. Results: DesAb-O was found to selectively detect synthetic Aβ42 oligomers both in vitro and in cultured cells, and to neutralise their associated neuronal dysfunction. DesAb-O can also identify Aβ42 oligomers present in the CSFs of AD patients with respect to healthy individuals, and completely prevent cell dysfunction induced by the administration of CSFs to neuronal cells. Conclusions: Taken together, our data indicate a promising method for the improvement of an early diagnosis of AD and for the generation of novel therapeutic approaches based on sdAbs for the treatment of AD and other devastating neurodegenerative conditions. [ABSTRACT FROM AUTHOR]

Amyloid fibril formation plays a central role in the pathogenesis of a number of neurodegenerative diseases, including Alzheimer and Parkinson diseases. Transient prefibrillar oligomers forming during the aggregation process, exhibiting a small size and a large hydrophobic surface, can aberrantly interact with a number of molecular targets on neurons, including the lipid bilayer of plasma membranes, resulting in a fatal outcome for the cells. By contrast, the mature fibrils, despite presenting generally a high hydrophobic surface, are endowed with a low diffusion rate and poorly penetrate the interior of the lipid bilayer. However, increasing evidence shows that both intracellular α‐synuclein fibrils, as well and as extracellular amyloid‐β and β2‐microglobulin fibrils, can release oligomers over time that quickly diffuse to reach the membrane of the neighboring cells. The persistent leakage of harmful oligomers from fibrils triggers an ongoing cascade of events resulting in a sustained injury to neurons and glia and also provides aggregates with the ability to cross biological membranes and diffuse between cells or cellular compartments. [ABSTRACT FROM AUTHOR]

The article discusses a number of neurodegenerative conditions are associated with the formation of cytosolic inclusions of TDP-43 within neurons. We expressed full-length TDP-43 in a motoneuron /neuroblastoma hybrid cell line and exploited the high-resolution power of stimulated emission depletion microscopy to monitor the changes of nuclear and cytoplasmic TDP-43 levels and the formation of various size classes of cytoplasmic TDP-43 aggregates with time.

Protein misfolding is a general hallmark of protein deposition diseases, such as Alzheimer’s disease or Parkinson’s disease, in which different types of aggregated species (oligomers, protofibrils and fibrils) are generated by the cells. Despite widespread interest, the relationship between oligomers and fibrils in the aggregation process and spreading remains elusive. A large variety of experimental evidences supported the idea that soluble oligomeric species of different proteins might be more toxic than the larger fibrillar forms. Furthermore, the lack of correlation between the presence of the typical pathological inclusions and disease sustained this debate. However, recent data show that the β-sheet core of the α-Synuclein (αSyn) fibrils is unable to establish persistent interactions with the lipid bilayers, but they can release oligomeric species responsible for an immediate dysfunction of the recipient neurons. Reversibly, such oligomeric species could also contribute to pathogenesis via neuron-to-neuron spreading by their direct cell-to-cell transfer or by generating new fibrils, following their neuronal uptake. In this Review, we discuss the various mechanisms of cellular dysfunction caused by αSyn, including oligomer toxicity, fibril toxicity and fibril spreading. [ABSTRACT FROM AUTHOR]

The onset and progression of numerous protein misfolding diseases are associated with the presence of oligomers formed during the aberrant aggregation of several different proteins, including amyloid-β (Aβ) in Alzheimer's disease and α-synuclein (αS) in Parkinson's disease. These small, soluble aggregates are currently major targets for drug discovery. In this study, we show that trodusquemine, a naturally-occurring aminosterol, markedly reduces the cytotoxicity of αS, Aβ and HypF-N oligomers to human neuroblastoma cells by displacing the oligomers from cell membranes in the absence of any substantial morphological and structural changes to the oligomers. These results indicate that the reduced toxicity results from a mechanism that is common to oligomers from different proteins, shed light on the origin of the toxicity of the most deleterious species associated with protein aggregation and suggest that aminosterols have the therapeutically-relevant potential to protect cells from the oligomer-induced cytotoxicity associated with numerous protein misfolding diseases. Limbocker et al. show that trodusquemine, an aminosterol, reduces the cytotoxicity of protein misfolded oligomers by displacing them from cell membranes in the absence of any overt structural/ morphological changes in them. This mechanism appears to be general, as they test it for oligomers of αS, Aβ and the model protein HypF-N to human neuroblastoma cells. [ABSTRACT FROM AUTHOR]

Oligomeric species populated during the aggregation process of a-synuclein have been linked to neuronal impairment in Parkinson's disease and related neurodegenerative disorders. By using solution and solid-state nuclear magnetic resonance techniques in conjunction with other structural methods, we identified the fundamental characteristics that enable toxic a-synuclein oligomers to perturb biological membranes and disrupt cellular function; these include a highly lipophilic element that promotes strong membrane interactions and a structured region that inserts into lipid bilayers and disrupts their integrity. In support of these conclusions, mutations that target the region that promotes strong membrane interactions by a-synuclein oligomers suppressed their toxicity in neuroblastoma cells and primary cortical neurons. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin positive inclusions (FTLD-U) are two clinically distinct neurodegenerative conditions sharing a similar histopathology characterized by the nuclear clearance of TDP-43 and its associated deposition into cytoplasmic inclusions in different areas of the central nervous system. Given the concomitant occurrence of TDP-43 nuclear depletion and cytoplasmic accumulation, it has been proposed that TDP-43 proteinopathies originate from either a loss-of-function (LOF) mechanism, a gain-of-function (GOF) process, or both. We have addressed this issue by transfecting murine NSC34 and N2a cells with siRNA for endogenous murine TDP-43 and with human recombinant TDP-43 inclusion bodies (IBs). These two strategies allowed the depletion of nuclear TDP-43 and the accumulation of cytoplasmic TDP-43 aggregates to occur separately and independently. Endogenous and exogenous TDP-43 were monitored and quantified using both immunofluorescence and Western blotting analysis, and nuclear functional TDP-43 was measured by monitoring the sortilin 1 mRNA splicing activity. Various degrees of TDP-43 cytoplasmic accumulation and nuclear TDP-43 depletion were achieved and the resulting cellular viability was evaluated, leading to a quantitative global analysis on the relative effects of LOF and GOF on the overall cytotoxicity. These were found to be ~55% and 45%, respectively, in both cell lines and using both readouts of cell toxicity, showing that these two mechanisms are likely to contribute apparently equally to the pathologies of ALS and FTLD-U. [ABSTRACT FROM AUTHOR]