Isogenic Human iPSC Parkinson’s Model Shows Nitrosative Stress-Induced Dysfunction in MEF2-PGC1α Transcription
01 Dec 2013-
TL;DR: Using a robust, patient-derived stem cell model of PD, the MEF2C-PGC1α pathway is identified as a therapeutic target to combat PD and mechanistic insight into gene-environmental interaction (GxE) in the pathogenesis of PD is provided.
Abstract: Parkinson’s disease (PD) is characterized by loss of A9 dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc). An association has been reported between PD and exposure to mitochondrial toxins, including environmental pesticides paraquat, maneb, and rotenone. Here, using a robust, patient-derived stem cell model of PD allowing comparison of A53T α-synuclein (α-syn) mutant cells and isogenic mutation-corrected controls, we identify mitochondrial toxin-induced perturbations in A53T α-syn A9 DA neurons (hNs). We report a pathway whereby basal and toxin-induced nitrosative/oxidative stress results in S-nitrosylation of transcription factor MEF2C in A53T hNs compared to corrected controls. This redox reaction inhibits the MEF2C-PGC1α transcriptional network, contributing to mitochondrial dysfunction and apoptotic cell death. Our data provide mechanistic insight into gene-environmental interaction (GxE) in the pathogenesis of PD. Furthermore, using small-molecule high-throughput screening, we identify the MEF2C-PGC1α pathway as a therapeutic target to combat PD.
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TL;DR: The progress in applications of iPSC technology that are particularly relevant to drug discovery and regenerative medicine are discussed, and the remaining challenges and the emerging opportunities in the field are considered.
Abstract: Since the advent of induced pluripotent stem cell (iPSC) technology a decade ago, human iPSCs have been widely used for disease modelling, drug discovery and cell therapy development. This article discusses progress in applications of iPSC technology that are particularly relevant to drug discovery and regenerative medicine, including the powerful combination of human iPSC technology with recent developments in gene editing.
985 citations
TL;DR: Recent evidence that supports the notion of neuron–neuron protein propagation is reviewed, with a focus on neuropathological and positron emission tomography imaging studies in humans.
Abstract: The progression of many neurodegenerative diseases is thought to be driven by the template-directed misfolding, seeded aggregation and cell-cell transmission of characteristic disease-related proteins, leading to the sequential dissemination of pathological protein aggregates. Recent evidence strongly suggests that the anatomical connections made by neurons - in addition to the intrinsic characteristics of neurons, such as morphology and gene expression profile - determine whether they are vulnerable to degeneration in these disorders. Notably, this common pathogenic principle opens up opportunities for pursuing novel targets for therapeutic interventions for these neurodegenerative disorders. We review recent evidence that supports the notion of neuron-neuron protein propagation, with a focus on neuropathological and positron emission tomography imaging studies in humans.
611 citations
TL;DR: Emerging themes in understanding of disease pathogenesis in synucleinopathies are discussed, including the contributions of aging, selective vulnerability and non-cell-autonomous factors such as α-synuclein cell-to-cell propagation and neuroinflammation.
Abstract: Alterations in α-synuclein dosage lead to familial Parkinson's disease (PD), and its accumulation results in synucleinopathies that include PD, dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). Furthermore, α-synuclein contributes to the fibrilization of amyloid-b and tau, two key proteins in Alzheimer's disease, which suggests a central role for α-synuclein toxicity in neurodegeneration. Recent studies of factors contributing to α-synuclein toxicity and its disruption of downstream cellular pathways have expanded our understanding of disease pathogenesis in synucleinopathies. In this Review, we discuss these emerging themes, including the contributions of aging, selective vulnerability and non-cell-autonomous factors such as α-synuclein cell-to-cell propagation and neuroinflammation. Finally, we summarize recent efforts toward the development of targeted therapies for PD and related synucleinopathies.
581 citations
TL;DR: A detailed overview of the mechanisms that can cause mitochondrial dysfunction in PD is provided and new signaling pathways such as the retromer‐trafficking pathway and its implication in the disease are brought to the forefront.
Abstract: Parkinson's disease (PD) is the second most common neurodegenerative disease. About 2% of the population above the age of 60 is affected by the disease. The pathological hallmarks of the disease include the loss of dopaminergic neurons in the substantia nigra and the presence of Lewy bodies that are made of α-synuclein. Several theories have been suggested for the pathogenesis of PD, of which mitochondrial dysfunction plays a pivotal role in both sporadic and familial forms of the disease. Dysfunction of the mitochondria that is caused by bioenergetic defects, mutations in mitochondrial DNA, nuclear DNA gene mutations linked to mitochondria, and changes in dynamics of the mitochondria such fusion or fission, changes in size and morphology, alterations in trafficking or transport, altered movement of mitochondria, impairment of transcription, and the presence of mutated proteins associated with mitochondria are implicated in PD. In this review, we provide a detailed overview of the mechanisms that can cause mitochondrial dysfunction in PD. We bring to the forefront, new signaling pathways such as the retromer-trafficking pathway and its implication in the disease and also provide a brief overview of therapeutic strategies to improve mitochondrial defects in PD. Bioenergetic defects, mutations in mitochondrial DNA, nuclear DNA gene mutations, alterations in mitochondrial dynamics, alterations in trafficking/transport and mitochondrial movement, abnormal size and morphology, impairment of transcription and the presence of mutated proteins associated with mitochondria are implicated in PD. In this review, we focus on the mechanisms underlying mitochondrial dysfunction in PD and bring to the forefront new signaling pathways that may be involved in PD. We also provide an overview of therapeutic strategies to improve mitochondrial defects in PD. This article is part of a special issue on Parkinson disease.
515 citations
TL;DR: The availability of human pluripotent stem cells (PSCs), which are capable of self-renewal and have the potential to differentiate into virtually any cell type, can now help to overcome the limitations of animal models for certain disorders.
Abstract: Experimental modelling of human disorders enables the definition of the cellular and molecular mechanisms underlying diseases and the development of therapies for treating them. The availability of human pluripotent stem cells (PSCs), which are capable of self-renewal and have the potential to differentiate into virtually any cell type, can now help to overcome the limitations of animal models for certain disorders. The ability to model human diseases using cultured PSCs has revolutionized the ways in which we study monogenic, complex and epigenetic disorders, as well as early- and late-onset diseases. Several strategies are used to generate such disease models using either embryonic stem cells (ES cells) or patient-specific induced PSCs (iPSCs), creating new possibilities for the establishment of models and their use in drug screening.
484 citations
References
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TL;DR: Induction of pluripotent stem cells from mouse embryonic or adult fibroblasts by introducing four factors, Oct3/4, Sox2, c-Myc, and Klf4, under ES cell culture conditions is demonstrated and iPS cells, designated iPS, exhibit the morphology and growth properties of ES cells and express ES cell marker genes.
23,959 citations
"Isogenic Human iPSC Parkinson’s Mod..." refers background in this paper
...Human epidemiological studies show association of PQ/MB exposure to development of PD (Costello et al., 2009), and this combination causes PD in animal models (Thiruchelvam et al., 2000)....
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TL;DR: PD models based on the manipulation of PD genes should prove valuable in elucidating important aspects of the disease, such as selective vulnerability of substantia nigra dopaminergic neurons to the degenerative process.
4,872 citations
"Isogenic Human iPSC Parkinson’s Mod..." refers background in this paper
...Two categories of cellular events have been uncovered in these studies: (1) protein misfolding, aggregation, and aberrant proteostasis and (2) mitochondrial damage with oxidative/nitrosative stress (Dauer and Przedborski, 2003)....
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TL;DR: It is proposed that this chemical selectively damages cells in the substantia nigra in patients who developed marked parkinsonism after using an illicit drug intravenously.
Abstract: Four persons developed marked parkinsonism after using an illicit drug intravenously. Analysis of the substance injected by two of these patients revealed primarily 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) with trace amounts of 1-methyl-4-phenyl-4-propionoxy-piperidine (MPPP). On the basis of the striking parkinsonian features observed in our patients, and additional pathological data from one previously reported case, it is proposed that this chemical selectively damages cells in the substantia nigra.
4,705 citations
"Isogenic Human iPSC Parkinson’s Mod..." refers background in this paper
...Mitochondrial toxins have been identified in epidemiological studies as contributing to ‘‘sporadic’’ PD, and mitochondrial-based toxin models gained attention following the discovery of MPTP-induced Parkinsonism (Langston et al., 1983)....
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TL;DR: The integration of this chemistry with current perspectives of NO biology illuminates many aspects of NO biochemistry, including the enzymatic mechanism of synthesis, the mode of transport and targeting in biological systems, the means by which its toxicity is mitigated, and the function-regulating interaction with target proteins.
Abstract: Nitric oxide (NO.), a potentially toxic molecule, has been implicated in a wide range of biological functions. Details of its biochemistry, however, remain poorly understood. The broader chemistry of nitrogen monoxide (NO) involves a redox array of species with distinctive properties and reactivities: NO+ (nitrosonium), NO., and NO- (nitroxyl anion). The integration of this chemistry with current perspectives of NO biology illuminates many aspects of NO biochemistry, including the enzymatic mechanism of synthesis, the mode of transport and targeting in biological systems, the means by which its toxicity is mitigated, and the function-regulating interaction with target proteins.
2,713 citations
"Isogenic Human iPSC Parkinson’s Mod..." refers background in this paper
...In addition to ROS, RNS such as nitric oxide (NO) have been linked to mitochondrial stress and can react with critical cysteine residues to affect functional activity via protein S-nitrosylation (forming SNO proteins) (Lei et al., 1992; Lipton et al., 1993; Stamler et al., 1992, 1997)....
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TL;DR: It is reported that NO.-mediated neurotoxicity is engendered, at least in part, by reaction with superoxide anion (O.-2), apparently leading to formation of peroxynitrite (ONOO−), and not by NO.
Abstract: Congeners of nitrogen monoxide (NO) are neuroprotective and neurodestructive. To address this apparent paradox, we considered the effects on neurons of compounds characterized by alternative redox states of NO: nitric oxide (NO.) and nitrosonium ion (NO+). Nitric oxide, generated from NO. donors or synthesized endogenously after NMDA (N-methyl-D-aspartate) receptor activation, can lead to neurotoxicity. Here, we report that NO.- mediated neurotoxicity is engendered, at least in part, by reaction with superoxide anion (O2.-), apparently leading to formation of peroxynitrite (ONOO-), and not by NO. alone. In contrast, the neuroprotective effects of NO result from downregulation of NMDA-receptor activity by reaction with thiol group(s) of the receptor's redox modulatory site. This reaction is not mediated by NO. itself, but occurs under conditions supporting S-nitrosylation of NMDA receptor thiol (reaction or transfer of NO+). Moreover, the redox versatility of NO allows for its interconversion from neuroprotective to neurotoxic species by a change in the ambient redox milieu. The details of this complex redox chemistry of NO may provide a mechanism for harnessing neuroprotective effects and avoiding neurotoxicity in the central nervous system.
2,478 citations
"Isogenic Human iPSC Parkinson’s Mod..." refers background in this paper
...In addition to ROS, RNS such as nitric oxide (NO) have been linked to mitochondrial stress and can react with critical cysteine residues to affect functional activity via protein S-nitrosylation (forming SNO proteins) (Lei et al., 1992; Lipton et al., 1993; Stamler et al., 1992, 1997)....
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