Current insights into the onset of dopaminergic (DA) neuronal dysfunction and/or death (hence, the etiology of Parkinson's Disease [PD]) implicate abnormalities in the unbiquitin-proteasome system (UPS) in response to oxidative and nitrosative stress, leading to protein misfolding. Protein misfolding appears to be mediated, at least in part, by S-nitrosylation of parkin or protein-disulfide isomerase (PDI). Hence, these molecules may provide mechanism-based biomarkers for impending neuronal demise or, conversely, if levels go down, their recovery. Dysfunctional mitochondria can lead to the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). In particular, there is growing evidence that mitochondrial complex 1 dysfunction results in an increase in ROS, eventually leading to the aggregation of a-synuclein. Oligomers/protofibrils of a-synuclein appear to play a central role in neurodegeneration - and, particularly, PD pathology -- likely through proteasome inhibition. Dysfunction of the UPS is likely the basis for familial PD characterized by mutations in Parkin, PINK1 and DJ-1. Recently, the Lipton group (Project 3) has demonstrated that S-nitrosylation of parkin or PDI, a key stress-induced chaperone in the endoplasmic reticulum (ER), has been linked to protein misfolding and neurodegeneration in PD models and in brains of PD patients. In addition, in preliminary studies, we have observed that mice carrying mutant a-synuclein (asyn) show dramatically increased S-nitrosylation of PDI;i.e., increased nitrosative/oxidative stress appears to be present in the context of such a mutation. There appears to be a developmental component to PD onset. For example, although, mutant a-syn is present in the earliest CNS progenitors of patients with some familial forms of PD, the disease does not typically manifest itself until adulthood. Progressive DA dysfunction also appears to be a component of the aging process. Immature neural progenitor cells appear to be resistant to oxidative stress in a manner not observed when those same cells become mature. Although human stem cells are typically studied for their therapeutic potential, they also provide (perhaps even more compellingly) models of human cellular development and offer the prospect for modeling human disease (from which novel therapies may, in turn, be derived). We have established defined culture conditions for modeling the iterative steps of DA neuronal development from an undifferentiated human embryonic stem cell (hESC) to a differentiated DA neuron in vitro. Cells at each developmental stage can be engineered to express mutant a-syn and/or """"""""lesioned"""""""" pharmacologically with mitochondrial complex inhibitors. In DA neurons, such manipulations produce features emulating PD. Therefore, we propose to use a human stem cell-based system to model the developmental susceptibility of neural precursors to oxidative/nitrosative stress relevant to PD in order to understand mechanisms by which endangered or dysfunctional DA neurons may ultimately be protected. A study of developmental susceptibility may help to develop drugs that will prevent oxidative/nitrosative stress in both endogenous and transplanted neural progenitors. Preserving mesostriatal circuitry is more tractable and safer than attempting to reconstruct proper new connections. However, if, in the future, transplantation into PD patients is required, protecting these exogenous stem cells will also be crucial. It is possible that different protective drugs will be necessary depending on the developmental stage of the neural progenitors used.

National Institute of Health (NIH)
National Institute of Environmental Health Sciences (NIEHS)
Research Program Projects (P01)
Project #
Application #
Study Section
Special Emphasis Panel (ZES1-LWJ-G)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Sanford-Burnham Medical Research Institute
La Jolla
United States
Zip Code
Oh, Chang-Ki; Sultan, Abdullah; Platzer, Joseph et al. (2017) S-Nitrosylation of PINK1 Attenuates PINK1/Parkin-Dependent Mitophagy in hiPSC-Based Parkinson's Disease Models. Cell Rep 21:2171-2182
Singec, Ilyas; Crain, Andrew M; Hou, Junjie et al. (2016) Quantitative Analysis of Human Pluripotency and Neural Specification by In-Depth (Phospho)Proteomic Profiling. Stem Cell Reports 7:527-542
Qu, Zhe; Greenlief, C Michael; Gu, Zezong (2016) Quantitative Proteomic Approaches for Analysis of Protein S-Nitrosylation. J Proteome Res 15:1-14
Spiering, Sean; Davidovics, Herman; Bushway, Paul J et al. (2015) High content screening for modulators of cardiac differentiation in human pluripotent stem cells. Methods Mol Biol 1263:43-61
Okamoto, Shu-ichi; Lipton, Stuart A (2015) S-Nitrosylation in neurogenesis and neuronal development. Biochim Biophys Acta 1850:1588-93
Satoh, Takumi; Stalder, Romain; McKercher, Scott R et al. (2015) Nrf2 and HSF-1 Pathway Activation via Hydroquinone-Based Proelectrophilic Small Molecules is Regulated by Electrochemical Oxidation Potential. ASN Neuro 7:
Zhou, Hui; Qu, Zhe; Mossine, Valeri V et al. (2014) Proteomic analysis of the effects of aged garlic extract and its FruArg component on lipopolysaccharide-induced neuroinflammatory response in microglial cells. PLoS One 9:e113531
Chan, Shing Fai; Sances, Sam; Brill, Laurence M et al. (2014) ATM-dependent phosphorylation of MEF2D promotes neuronal survival after DNA damage. J Neurosci 34:4640-53
Okamoto, Shu-Ichi; Nakamura, Tomohiro; Cieplak, Piotr et al. (2014) S-nitrosylation-mediated redox transcriptional switch modulates neurogenesis and neuronal cell death. Cell Rep 8:217-28
Qu, Zhe; Meng, Fanjun; Zhou, Hui et al. (2014) NitroDIGE analysis reveals inhibition of protein S-nitrosylation by epigallocatechin gallates in lipopolysaccharide-stimulated microglial cells. J Neuroinflammation 11:17

Showing the most recent 10 out of 61 publications