Tau aggregation induces cell death in iPSC-derived neurons.

In Vivo Restoration of Physiological Levels of Truncated TrkB.T1 Receptor Rescues Neuronal Cell Death in a Trisomic Mouse Model

Disease-associated oligodendrocyte signatures in neurodegenerative disease: the known and unknown.

BackgroundMitochondrial dysfunctions are a key hallmark of Alzheimer’s disease (AD). β‐Lactolin, a whey‐derived glycine–threonine–tryptophan–tyrosine tetrapeptide, has been previously reported to prevent AD‐like pathologies in an 5×FAD mouse model via regulation of microglial functions. However, the direct effect of β‐lactolin on neuronal cells and neuronal mitochondrial functions remains unknown. Here, we investigated the effects of β‐lactolin on mitochondrial dysfunctions in amyloid β (Aβ)‐treated mouse hippocampal neuronal HT22 cells and human induced‐pluripotent cell (hiPSC)‐derived AD model neurons.MethodMouse hippocampal neuronal HT22 cell line, and hiPSC‐derived AD model neuron (PSEN1 P117L mutation) and its wild‐type control were used in this study. HT22 cells were treated with β‐lactolin (1–100 nM) for 1 hr, and Aβ42 (1–10 μM) was added for the next 23 hrs. Oxygen consumption rate was measured using extracellular flux analyzer. Intracellular ATP level was determined by luciferase activity. Cells were stained with MitoTracker, JC‐1, or MitoSOX fluorescent dye, and then mitochondrial morphologies, membrane potential, and oxidative stress, respectively, were examined by high content image analysis. Cell viability was measured by MTT assay. Gene expression levels were evaluated by RT‐PCR. hiPSC‐derived wild‐type and AD neurons were cultured for 14 days under β‐lactolin treatment, and mitochondrial morphologies and membrane potentials were analyzed.ResultHT22 cells treated with both β‐lactolin and Aβ exhibited increased oxygen consumption rate and cellular ATP concentrations compared to cells treated with Aβ alone, suggesting that β‐lactolin improves mitochondrial respiration and energy production. In high content image analysis, β‐lactolin attenuated Aβ‐induced mitochondrial fragmentation, membrane potential decrease, and excess oxidative stress, eventually preventing neuronal cell death. Treatments with β‐lactolin increased gene expression of mitofusin‐2, which contribute to mitochondrial fusion events. Finally, β‐lactolin attenuated impairment in both mitochondrial morphologies and membrane potentials in hiPSC‐derived AD model neurons, suggesting β‐lactolin shows a suppressing effect on human AD pathologies.Conclusionβ‐lactolin improved AD‐related neuronal mitochondrial dysfunctions and suppressed neuronal cell death in both mouse and human AD model neuronal cells. The dual function of β‐lactolin on both neuron and microglia marks an advantage in AD prevention.

Previous studies have shown that in neuronal cells the developmental phenomenon of programmed cell death is an active process, requiring synthesis of both RNA and protein. This presumably reflects a requirement for novel gene products to effect cell death. It is shown here that the death of nerve growth factor-deprived neuronal PC12 cells occurs at the same rate as that of rat sympathetic neurons and, like rat sympathetic neurons, involves new transcription and translation. In nerve growth factor-deprived neuronal PC12 cells, a decline in metabolic activity, assessed by uptake of [3H]2-deoxyglucose, precedes the decline in cell number, assessed by counts of trypan blue-excluding cells. Both declines are prevented by actinomycin D and anisomycin. In contrast, the death of nonneuronal (chromaffin-like) PC12 cells is not inhibited by transcription or translation inhibitors and thus does not require new protein synthesis. DNA fragmentation by internucleosomal cleavage does not appear to be a consistent or significant aspect of cell death in sympathetic neurons, neuronal PC12 cells, or nonneuronal PC12 cells, notwithstanding that the putative nuclease inhibitor aurintricarboxylic acid protects sympathetic neurons, as well as neuronal and nonneuronal PC12 cells, from death induced by trophic factor removal. Both phenotypic classes of PC12 cells respond to aurintricarboxylic acid with similar dose-response characteristics. Our results indicate that programmed cell death in neuronal PC12 cells, but not in nonneuronal PC12 cells, resembles programmed cell death in sympathetic neurons in significant mechanistic aspects: time course, role of new protein synthesis, and lack of a significant degree of DNA fragmentation.

A Convoluted Way to Die

Event Abstract Back to Event Neuroprotective and Neurotherapeutic Effects of Bee Venom on Neurodegenerative Diseases Miran K. Rakha1* 1 Suez Canal University, Biotechnology Research Center, Egypt Acute and chronic neurodegenerative diseases are illnesses associated with high morbidity and mortality, and few or no effective options are available for their treatment. A characteristic of many neurodegenerative diseases — which include stroke, brain trauma, spinal cord injury, amyotrophic lateral sclerosis, Huntington’s disease, Alzheimer’s disease, and Parkinson’s disease — is neuronal cell death. Given that central nervous system tissue has very limited, if any, regenerative capacity, it is of utmost importance to limit the damage caused by neuronal death. Bee venom, which is also known as apitoxin, consists of several biologically active peptides, including melittin, adolapin, mast cell degranulating peptide and phospholipase A2. Moreover, bee venom contains a variety of bioamines, such as apamin, histamine, procamine, serotonin, and norepinephrine, which facilitate nerve transmission and healing in a variety of nerve disorders. This gives bee venom the ability to travel along the neural pathways from the spine to various trigger points and injured areas to help repair nerve damage and restore mobility. This review overviews; (1) causes and mechanisms of neurodegenerative diseases which pertains to neuronal cell death, (2) evidence linking composition comprising bee venom to its substantial potential for preventing and treating of neurodegenerative diseases associated with neuronal cell death, and (3) how improving our knowledge of the mechanisms mediating neuroprotective and neurotherapeutic activities of bee venom against neuronal cell death may led to novel therapeutic strategies for the treatment of neurodegenerative diseases. Future challenges remaining will be to elucidate signaling responses activated by bee venom in neurons. In other words, bee venom inhibits neuronal cell death and activation of proapoptotic signaling in neurons. These findings emphasize the clinical importance of bee venom for treatment of neurodegenerative diseases. Further investigation is necessary to elaborate the mechanisms involved and to permit full exploitation of neuroprotective and neurotherapeutic potentials of bee venom. References Doo AR et al. (2012): Bee venom protects SH-SY5Y human neuroblastoma cells from 1-methyl-4-phenylpyridinium-induced apoptotic cell death. Brain Res, 1429: 106-115. Lee SM et al. (2012): Effects of Bee Venom on Glutamate-Induced Toxicity in Neuronal and Glial Cells. Evidence-Based Complementary and Alternative Medicine, 2012: 368196, doi:10.1155/2012/368196. Rakha MK (2011): Impact of Beehive Products on the Cardiovascular Neurophysiology Expands Novel Horizons in Apitherapy. Conference Abstract: 10th Meeting of the Société des Neurosciences, May 24-27, 2011, Marseille, France. Yang EJ et al. (2011): Melittin restores proteasome function in an animal model of ALS. J Neuroinflammation, 8: 69, doi: 10.1186/1742-2094-8-69. Yang EJ et al. (2010): Bee venom attenuates neuroinflammatory events and extends survival in amyotrophic lateral sclerosis models. J Neuroinflammation, 7: 69, doi: 10.1186/1742-2094-7-69. Keywords: Bee Venom, Neuroprotective Activity, Neurotherapeutic Potential, Neuronal Cells, Neurodegenerative Diseases. Conference: 4th Conference of the Mediterrarnean Neuroscience Society, Istanbul, Turkey, 30 Sep - 3 Oct, 2012. Presentation Type: Poster Presentation Topic: Abstracts Citation: Rakha MK (2013). Neuroprotective and Neurotherapeutic Effects of Bee Venom on Neurodegenerative Diseases. Conference Abstract: 4th Conference of the Mediterrarnean Neuroscience Society. doi: 10.3389/conf.fnhum.2013.210.00057 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 26 Jan 2013; Published Online: 11 Apr 2013. * Correspondence: Dr. Miran K Rakha, Suez Canal University, Biotechnology Research Center, Ismailia, Egypt, mirankhalil@hotmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract Supplemental Data The Authors in Frontiers Miran K Rakha Google Miran K Rakha Google Scholar Miran K Rakha PubMed Miran K Rakha Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The dysfunction of proteasomes and mitochondria has been implicated in the pathogenesis of Parkinson disease. However, the mechanism by which this dysfunction causes neuronal cell death is unknown. We studied the role of cyclin-dependent kinase 5 (Cdk5)-p35 in the neuronal cell death induced by 1-methyl-4-phenylpyrinidinium ion (MPP+), which has been used as an in vitro model of Parkinson disease. When cultured neurons were treated with 100 microM MPP+, p35 was degraded by proteasomes at 3 h, much earlier than the neurons underwent cell death at 12-24 h. The degradation of p35 was accompanied by the down-regulation of Cdk5 activity. We looked for the primary target of MPP+ that triggered the proteasome-mediated degradation of p35. MPP+ treatment for 3 h induced the fragmentation of the mitochondria, reduced complex I activity of the respiratory chain without affecting ATP levels, and impaired the mitochondrial import system. The dysfunction of the mitochondrial import system is suggested to up-regulate proteasome activity, leading to the ubiquitin-independent degradation of p35. The overexpression of p35 attenuated MPP+-induced neuronal cell death. In contrast, depletion of p35 with short hairpin RNA not only induced cell death but also sensitized to MPP+ treatment. These results indicate that a brief MPP+ treatment triggers the delayed neuronal cell death by the down-regulation of Cdk5 activity via mitochondrial dysfunction-induced up-regulation of proteasome activity. We propose a role for Cdk5-p35 as a survival factor in countering MPP+-induced neuronal cell death.

Microglia Activated with the Toll-Like Receptor 9 Ligand CpG Attenuate Oligomeric Amyloid β Neurotoxicity in in Vitro and in Vivo Models of Alzheimer’s Disease

An intronic expansion of GGGGCC repeats within the C9ORF72 gene is the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia (ALS-FTD). Ataxin-2 with intermediate length of polyglutamine expansions (Ataxin-2 Q30x) is a genetic modifier of the disease. Here, we found that C9ORF72 forms a complex with the WDR41 and SMCR8 proteins to act as a GDP/GTP exchange factor for RAB8a and RAB39b and to thereby control autophagic flux. Depletion of C9orf72 in neurons partly impairs autophagy and leads to accumulation of aggregates of TDP-43 and P62 proteins, which are histopathological hallmarks of ALS-FTD SMCR8 is phosphorylated by TBK1 and depletion of TBK1 can be rescued by phosphomimetic mutants of SMCR8 or by constitutively active RAB39b, suggesting that TBK1, SMCR8, C9ORF72, and RAB39b belong to a common pathway regulating autophagy. While depletion of C9ORF72 only has a partial deleterious effect on neuron survival, it synergizes with Ataxin-2 Q30x toxicity to induce motor neuron dysfunction and neuronal cell death. These results indicate that partial loss of function of C9ORF72 is not deleterious by itself but synergizes with Ataxin-2 toxicity, suggesting a double-hit pathological mechanism in ALS-FTD.

Planar cell polarity (PCP) describes a cell-cell communication process through which individual cells coordinate and align within the plane of a tissue. In this study, we show that overexpression of Fuz, a PCP gene, triggers neuronal apoptosis via the dishevelled/Rac1 GTPase/MEKK1/JNK/caspase signalling axis. Consistent with this finding, endogenous Fuz expression is upregulated in models of polyglutamine (polyQ) diseases and in fibroblasts from spinocerebellar ataxia type 3 (SCA3) patients. The disruption of this upregulation mitigates polyQ-induced neurodegeneration in Drosophila We show that the transcriptional regulator Yin Yang 1 (YY1) associates with the Fuz promoter. Overexpression of YY1 promotes the hypermethylation of Fuz promoter, causing transcriptional repression of Fuz Remarkably, YY1 protein is recruited to ATXN3-Q84 aggregates, which reduces the level of functional, soluble YY1, resulting in Fuz transcriptional derepression and induction of neuronal apoptosis. Furthermore, Fuz transcript level is elevated in amyloid beta-peptide, Tau and α-synuclein models, implicating its potential involvement in other neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Taken together, this study unveils a generic Fuz-mediated apoptotic cell death pathway in neurodegenerative disorders.

Copyright: © 2013 Gu H. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases, which is characterized by a progressive and age-related chronic loss of neurons in extensive brain areas, such as cerebral cortex and hippocampus, one of the most prominent being the basal forebrain cholinergic neurons (BFCN). In clinic, patients suffer from impairment of memory and cognitive function, language breakdown and eventually long-term memory loss. The burden of AD is heavy to patient’s families and the whole society. The pathological findings of AD are senile plaques, neurofibrillary tangles and neuronal cell death. Senile plaques and neurofibrillary tangles are mainly consisted of β-amyloid (Aβ) peptides, which are formed by the cleavage of amyloid precursor protein (APP) by βand γ-secretase. In the end, accumulation of Aβ peptides in neurons causes neuronal degeneration and cell death [1,2]. Although previous studies already showed the effects of Aβ peptides on cultured mammal neurons, how Aβ peptides affect human neurons, especially neurons from AD patients, are still not understood. On the other hand, although neurotrophic factors application, such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), have showed functional recovery in animal model of AD and several drugs for the treatment of AD has been approved by FDA and have shown the improvement of cognitive function and memory of AD patient, it is still challenge to delay and reverse the neuronal degeneration and cell death [3-5].

Impedance measurement for real time detection of neuronal cell death

Neuronal cell death is the central abnormality occurring in brains suffering from Alzheimer's disease (AD). The notion that AD is a disease caused by loss of neurons points toward suppression of neuronal death as the most important therapeutic target. Nevertheless, the mechanisms for neuronal death in AD are still relatively unclear. Three known mutant genes cause familial AD (FAD): amyloid precursor protein, presenilin 1, and presenilin 2. Detailed analysis of cytotoxic mechanisms of the FAD-linked mutant genes reveals that they cause neuronal cell death at physiologically low expression levels. Unexpectedly, cytotoxic mechanisms vary depending on the type of mutations and genes, suggesting that various mechanisms for neuronal cell death are involved in AD patients. In support of this, activity-dependent neurotrophic factor, basic fibroblast growth factor, and insulin-like growth factor-I can completely protect neurons from beta-amyloid (A beta) cytotoxicity but exhibit incomplete or little effect on cytotoxicity by FAD mutant genes. By contrast, Humanin, a newly identified 24-residue peptide, suppresses neuronal cell death by various FAD mutants and A beta, whereas this factor has no effect on cytotoxicity from AD-irrelevant insults. Studies investigating death and survival of neuronal cells exposed to AD insults will open a new horizon in developing therapy aimed at neuroprotection.

Causal Role of Apoptosis-Inducing Factor for Neuronal Cell Death Following Traumatic Brain Injury

Gaucher disease (GD) is a lysosomal storage disorder caused by a mutation in the GBA1 gene, responsible for encoding the enzyme Glucocerebrosidase (GCase). Although neuronal death and neuroinflammation have been observed in the brains of individuals with neuronopathic Gaucher disease (nGD), the exact mechanism underlying neurodegeneration in nGD remains unclear. In this study, we used two induced pluripotent stem cells (iPSCs)-derived neuronal cell lines acquired from two type-3 GD patients (GD3-1 and GD3-2) to investigate the mechanisms underlying nGD by biochemical analyses. These iPSCs-derived neuronal cells from GD3-1 and GD3-2 exhibit an impairment in endoplasmic reticulum (ER) calcium homeostasis and an increase in unfolded protein response markers (BiP and CHOP), indicating the presence of ER stress in nGD. A significant increase in the BAX/BCL-2 ratio and an increase in Annexin V-positive cells demonstrate a notable increase in apoptotic cell death in GD iPSCs-derived neurons, suggesting downstream signaling after an increase in the unfolded protein response. Our study involves the establishment of iPSCs-derived neuronal models for GD and proposes a possible mechanism underlying nGD. This mechanism involves the activation of ER stress and the unfolded protein response, ultimately leading to apoptotic cell death in neurons.