scholarly journals Epigenomic analysis of Parkinson’s disease neurons identifies Tet2 loss as neuroprotective

2019 ◽  
Author(s):  
Marshall Lee ◽  
Killinger Bryan ◽  
Li Peipei ◽  
Ensink Elizabeth ◽  
Li Katie ◽  
...  
Keyword(s):  
Immune Responses ◽  
Neuronal Cell ◽  
Neuronal Loss ◽  
Genome Wide ◽  
Dopaminergic Neuronal Loss ◽  
Activation Pathways ◽  
Neuronal Functions ◽  
Novel Therapeutic ◽  
Cytosine Modification

AbstractPD pathogenesis may involve the epigenetic control of enhancers that modify neuronal functions. Here, we comprehensively profile DNA methylation at enhancers, genome-wide, in neurons of 57 PD patients and 48 control individuals. We found a widespread increase in cytosine modifications at enhancers in PD neurons, which is partly explained by elevated hydroxymethylation levels. Epigenetic dysregulation of enhancers in PD converge on transcriptional abnormalities affecting neuronal signaling and immune activation pathways. In particular, PD patients exhibit an epigenetic and transcriptional upregulation of TET2, a master-regulator of cytosine modification status. TET2 inactivation in a neuronal cell line results in cytosine modification changes that are reciprocal to those observed in PD neurons. Furthermore, Tet2 inactivation in mice fully prevents dopaminergic neuronal loss in the substantia nigra induced by prior inflammation. Tet2 loss in mice also attenuates transcriptional immune responses to an inflammatory trigger. Thus, widespread epigenetic dysregulation of enhancers in PD neurons may, in part, be mediated by increased TET2 expression. Decreased Tet2 activity is neuroprotective, in vivo, and may be a novel therapeutic target for PD.

scholarly journals Overexpression of Mitochondrial Calcium Uniporter Causes Neuronal Death

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Veronica Granatiero ◽  
Marco Pacifici ◽  
Anna Raffaello ◽  
Diego De Stefani ◽  
Rosario Rizzuto
Keyword(s):  
Cell Fate ◽  
Neuronal Death ◽  
Cortical Neurons ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Neuronal Loss ◽  
Calcium Uniporter ◽  
Organelle Morphology

Neurodegenerative diseases are a large and heterogeneous group of disorders characterized by selective and progressive death of specific neuronal subtypes. In most of the cases, the pathophysiology is still poorly understood, although a number of hypotheses have been proposed. Among these, dysregulation of Ca2+ homeostasis and mitochondrial dysfunction represent two broadly recognized early events associated with neurodegeneration. However, a direct link between these two hypotheses can be drawn. Mitochondria actively participate to global Ca2+ signaling, and increases of [Ca2+] inside organelle matrix are known to sustain energy production to modulate apoptosis and remodel cytosolic Ca2+ waves. Most importantly, while mitochondrial Ca2+ overload has been proposed as the no-return signal, triggering apoptotic or necrotic neuronal death, until now direct evidences supporting this hypothesis, especially in vivo, are limited. Here, we took advantage of the identification of the mitochondrial Ca2+ uniporter (MCU) and tested whether mitochondrial Ca2+ signaling controls neuronal cell fate. We overexpressed MCU both in vitro, in mouse primary cortical neurons, and in vivo, through stereotaxic injection of MCU-coding adenoviral particles in the brain cortex. We first measured mitochondrial Ca2+ uptake using quantitative genetically encoded Ca2+ probes, and we observed that the overexpression of MCU causes a dramatic increase of mitochondrial Ca2+ uptake both at resting and after membrane depolarization. MCU-mediated mitochondrial Ca2+ overload causes alteration of organelle morphology and dysregulation of global Ca2+ homeostasis. Most importantly, MCU overexpression in vivo is sufficient to trigger gliosis and neuronal loss. Overall, we demonstrated that mitochondrial Ca2+ overload is per se sufficient to cause neuronal cell death both in vitro and in vivo, thus highlighting a potential key step in neurodegeneration.

scholarly journals Polygonatum sibiricum Polysaccharides Protect against MPP-Induced Neurotoxicity via the Akt/mTOR and Nrf2 Pathways

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Si Huang ◽  
Haiyan Yuan ◽  
Wenqun Li ◽  
Xinyi Liu ◽  
Xiaojie Zhang ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Neuronal Loss ◽  
Heme Oxygenase 1 ◽  
Related Factor ◽  
Dependent Manner ◽  
Quinone Oxidoreductase ◽  
Glutamate Cysteine Ligase ◽  
Dopaminergic Neuronal Loss

Polygonatum sibiricum, a well-known life-prolonging tonic in Chinese medicine, has been widely used for nourishing nerves in the orient, but the underlying molecular mechanisms remain unclear. In this study, we found that P. sibiricum polysaccharides (PSP) ameliorated 1-methyl-4-phenyl-1,2.3,6-tetrahydropyridine- (MPTP-) induced locomotor activity deficiency and dopaminergic neuronal loss in an in vivo Parkinson’s disease (PD) mouse model. Additionally, PSP pretreatment inhibited N-methyl-4-phenylpyridine (MPP+) induced the production of reactive oxygen species, increasing the ratio of reduced glutathione/oxidized glutathione. In vitro experiments showed that PSP promoted the proliferation of N2a cells in a dose-dependent manner, while exhibiting effects against oxidative stress and neuronal apoptosis elicited by MPP+. These effects were found to be associated with the activation of Akt/mTOR-mediated p70S6K and 4E-BP1 signaling pathways, as well as nuclear factor erythroid 2-related factor 2- (Nrf2-) mediated NAD(P)H quinone oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (Gclc), and glutamate-cysteine ligase modulatory subunit (Gclm), resulting in antiapoptotic and antioxidative effects. Meanwhile, PSP exhibited no chronic toxicity in C57BJ/6 mice. Together, our results suggest that PSP can serve as a promising therapeutic candidate with neuroprotective properties in preventing PD.

scholarly journals Dual Targeting by Inhibition of Phosphoinositide-3-Kinase and Mammalian Target of Rapamycin Attenuates the Neuroinflammatory Responses in Murine Hippocampal Cells and Seizures in C57BL/6 Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Preeti Vyas ◽  
Rajkumar Tulsawani ◽  
Divya Vohora
Keyword(s):  
Cell Signaling ◽  
Day Treatment ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Neuronal Loss ◽  
Ht22 Cells ◽  
Seizure Severity ◽  
Combination Model

Emerging evidence suggests the association of seizures and inflammation; however, underlying cell signaling mechanisms are still not fully understood. Overactivation of phosphoinositide-3-kinases is associated with both neuroinflammation and seizures. Herein, we speculate the PI3K/Akt/mTOR pathway as a promising therapeutic target for neuroinflammation-mediated seizures and associated neurodegeneration. Firstly, we cultured HT22 cells for detection of the downstream cell signaling events activated in a lipopolysaccharide (LPS)-primed pilocarpine (PILO) model. We then evaluated the effects of 7-day treatment of buparlisib (PI3K inhibitor, 25 mg/kg p.o.), dactolisib (PI3K/mTOR inhibitor, 25 mg/kg p.o.), and rapamycin (mTORC1 inhibitor, 10 mg/kg p.o.) in an LPS-primed PILO model of seizures in C57BL/6 mice. LPS priming resulted in enhanced seizure severity and reduced latency. Buparlisib and dactolisib, but not rapamycin, prolonged latency to seizures and reduced neuronal loss, while all drugs attenuated seizure severity. Buparlisib and dactolisib further reduced cellular redox, mitochondrial membrane potential, cleaved caspase-3 and p53, nuclear integrity, and attenuated NF-κB, IL-1β, IL-6, TNF-α, and TGF-β1 and TGF-β2 signaling both in vitro and in vivo post-PILO and LPS+PILO inductions; however, rapamycin mitigated the same only in the PILO model. Both drugs protected against neuronal cell death demonstrating the contribution of this pathway in the seizure-induced neuronal pyknosis; however, rapamycin showed resistance in a combination model. Furthermore, LPS and PILO exposure enhanced pAkt/Akt and phospho-p70S6/total-p70S6 kinase activity, while buparlisib and dactolisib, but not rapamycin, could reduce it in a combination model. Partial rapamycin resistance was observed possibly due to the reactivation of the pathway by a functionally different complex of mTOR, i.e., mTORC2. Our study substantiated the plausible involvement of PI3K-mediated apoptotic and inflammatory pathways in LPS-primed PILO-induced seizures and provides evidence that its modulation constitutes an anti-inflammatory mechanism by which seizure inhibitory effects are observed. We showed dual inhibition by dactolisib as a promising approach. Targeting this pathway at two nodes at a time may provide new avenues for antiseizure therapies.

scholarly journals Loss of MicroRNA-7 Regulation Leads to α-Synuclein Accumulation and Dopaminergic Neuronal Loss In Vivo

2017 ◽  
Vol 25 (10) ◽  
pp. 2404-2414 ◽  
Author(s):  
Kirsty J. McMillan ◽  
Tracey K. Murray ◽  
Nora Bengoa-Vergniory ◽  
Oscar Cordero-Llana ◽  
Jane Cooper ◽  
...  
Keyword(s):  
Neuronal Loss ◽  
Dopaminergic Neuronal Loss

scholarly journals Discovery of a Necroptosis Inhibitor Improving Dopaminergic Neuronal Loss after MPTP Exposure in Mice

2021 ◽  
Vol 22 (10) ◽  
pp. 5289
Author(s):  
Sara R. Oliveira ◽  
Pedro A. Dionísio ◽  
Maria M. Gaspar ◽  
Maria B. T. Ferreira ◽  
Catarina A. B. Rodrigues ◽  
...  
Keyword(s):  
Neurodegenerative Disorder ◽  
Neuronal Loss ◽  
Substantia Nigra Pars Compacta ◽  
Drug Candidate ◽  
Motor Deficits ◽  
Interacting Protein ◽  
Microglia Cell ◽  
Murine Microglia ◽  
Dopaminergic Neuronal Loss

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, mainly characterized by motor deficits correlated with progressive dopaminergic neuronal loss in the substantia nigra pars compacta (SN). Necroptosis is a caspase-independent form of regulated cell death mediated by the concerted action of receptor-interacting protein 3 (RIP3) and the pseudokinase mixed lineage domain-like protein (MLKL). It is also usually dependent on RIP1 kinase activity, influenced by further cellular clues. Importantly, necroptosis appears to be strongly linked to several neurodegenerative diseases, including PD. Here, we aimed at identifying novel chemical inhibitors of necroptosis in a PD-mimicking model, by conducting a two-step screening. Firstly, we phenotypically screened a library of 31 small molecules using a cellular model of necroptosis and, thereafter, the hit compound effect was validated in vivo in a sub-acute 1-methyl-1-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP) PD-related mouse model. From the initial compounds, we identified one hit—Oxa12—that strongly inhibited necroptosis induced by the pan-caspase inhibitor zVAD-fmk in the BV2 murine microglia cell line. More importantly, mice exposed to MPTP and further treated with Oxa12 showed protection against MPTP-induced dopaminergic neuronal loss in the SN and striatum. In conclusion, we identified Oxa12 as a hit compound that represents a new chemotype to tackle necroptosis. Oxa12 displays in vivo effects, making this compound a drug candidate for further optimization to attenuate PD pathogenesis.

scholarly journals Axonal Transport as an In Vivo Biomarker for Retinal Neuropathy

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1298
Author(s):  
Lucia G. Le Roux ◽  
Xudong Qiu ◽  
Megan C. Jacobsen ◽  
Mark D. Pagel ◽  
Seth T. Gammon ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Vision Loss ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Neuronal Loss ◽  
Fluorescent Imaging ◽  
Imaging Agent ◽  
Imaging Biomarker ◽  
Fast Axonal Transport

We illuminate a possible explanatory pathophysiologic mechanism for retinal cellular neuropathy by means of a novel diagnostic method using ophthalmoscopic imaging and a molecular imaging agent targeted to fast axonal transport. The retinal neuropathies are a group of diseases with damage to retinal neural elements. Retinopathies lead to blindness but are typically diagnosed late, when substantial neuronal loss and vision loss have already occurred. We devised a fluorescent imaging agent based on the non-toxic C fragment of tetanus toxin (TTc), which is taken up and transported in neurons using the highly conserved fast axonal transport mechanism. TTc serves as an imaging biomarker for normal axonal transport and demonstrates impairment of axonal transport early in the course of an N-methyl-D-aspartic acid (NMDA)-induced excitotoxic retinopathy model in rats. Transport-related imaging findings were dramatically different between normal and retinopathic eyes prior to presumed neuronal cell death. This proof-of-concept study provides justification for future clinical translation.

scholarly journals Meningeal inflammation in multiple sclerosis induces phenotypic changes in cortical microglia that differentially associate with neurodegeneration

2021 ◽  
Author(s):  
Lynn van Olst ◽  
Carla Rodriguez-Mogeda ◽  
Carmen Picon ◽  
Svenja Kiljan ◽  
Rachel E. James ◽  
...  
Keyword(s):  
Animal Model ◽  
Neuronal Cell ◽  
Neuronal Loss ◽  
Activation Markers ◽  
Post Induction ◽  
Meningeal Inflammation ◽  
Neuronal Cell Bodies ◽  
Neuronal Soma ◽  
Cortical Pathology

AbstractMeningeal inflammation strongly associates with demyelination and neuronal loss in the underlying cortex of progressive MS patients, thereby contributing significantly to clinical disability. However, the pathological mechanisms of meningeal inflammation-induced cortical pathology are still largely elusive. By extensive analysis of cortical microglia in post-mortem progressive MS tissue, we identified cortical areas with two MS-specific microglial populations, termed MS1 and MS2 cortex. The microglial population in MS1 cortex was characterized by a higher density and increased expression of the activation markers HLA class II and CD68, whereas microglia in MS2 cortex showed increased morphological complexity and loss of P2Y12 and TMEM119 expression. Interestingly, both populations associated with inflammation of the overlying meninges and were time-dependently replicated in an in vivo rat model for progressive MS-like chronic meningeal inflammation. In this recently developed animal model, cortical microglia at 1-month post-induction of experimental meningeal inflammation resembled microglia in MS1 cortex, and microglia at 2 months post-induction acquired a MS2-like phenotype. Furthermore, we observed that MS1 microglia in both MS cortex and the animal model were found closely apposing neuronal cell bodies and to mediate pre-synaptic displacement and phagocytosis, which coincided with a relative sparing of neurons. In contrast, microglia in MS2 cortex were not involved in these synaptic alterations, but instead associated with substantial neuronal loss. Taken together, our results show that in response to meningeal inflammation, microglia acquire two distinct phenotypes that differentially associate with neurodegeneration in the progressive MS cortex. Furthermore, our in vivo data suggests that microglia initially protect neurons from meningeal inflammation-induced cell death by removing pre-synapses from the neuronal soma, but eventually lose these protective properties contributing to neuronal loss.

scholarly journals Icariin Reduces Dopaminergic Neuronal Loss and Microglia-Mediated Inflammation in Vivo and in Vitro

2018 ◽  
Vol 10 ◽  
Author(s):  
Guo-Qing Wang ◽  
Dai-Di Li ◽  
Chun Huang ◽  
Di-Sheng Lu ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Neuronal Loss ◽  
Dopaminergic Neuronal Loss

scholarly journals Perturbation of Transcription Factor Nur77 Expression Mediated by Myocyte Enhancer Factor 2D (MEF2D) Regulates Dopaminergic Neuron Loss in Response to 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)

2013 ◽  
Vol 288 (20) ◽  
pp. 14362-14371 ◽  
Author(s):  
Matthew P. Mount ◽  
Yi Zhang ◽  
Mandana Amini ◽  
Steve Callaghan ◽  
Jerzy Kulczycki ◽  
...  
Keyword(s):  
Critical Role ◽  
Neuronal Loss ◽  
Nigrostriatal System ◽  
Myocyte Enhancer Factor ◽  
Mptp Treatment ◽  
Dopaminergic Neuronal Loss ◽  
Dopaminergic Neuron Loss ◽  
Enhancer Factor

We have earlier reported the critical nature of calpain-CDK5-MEF2 signaling in governing dopaminergic neuronal loss in vivo. CDK5 mediates phosphorylation of the neuronal survival factor myocyte enhancer factor 2 (MEF2) leading to its inactivation and loss. However, the downstream factors that mediate MEF2-regulated survival are unknown. Presently, we define Nur77 as one such critical downstream survival effector. Following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment in vivo, Nur77 expression in the nigrostriatal region is dramatically reduced. This loss is attenuated by expression of MEF2. Importantly, MEF2 constitutively binds to the Nur77 promoter in neurons under basal conditions. This binding is lost following 1-methyl-4-phenylpyridinium treatment. Nur77 deficiency results in significant sensitization to dopaminergic loss following 1-methyl-4-phenylpyridinium/MPTP treatment, in vitro and in vivo. Furthermore, Nur77-deficient MPTP-treated mice displayed significantly reduced levels of dopamine and 3,4-Dihydroxyphenylacetic acid in the striatum as well as elevated post synaptic FosB activity, indicative of increased nigrostriatal damage when compared with WT MPTP-treated controls. Importantly, this sensitization in Nur77-deficient mice was rescued with ectopic Nur77 expression in the nigrostriatal system. These results indicate that the inactivation of Nur77, induced by loss of MEF2 activity, plays a critical role in nigrostriatal degeneration in vivo.

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