MP02:Hasson:parkinsons mitoqc

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Author(s) name and affiliation: Samuel A. Hasson1,2, Scott Martin2, Eugen Buehler2, James Inglese2, and Richard Youle1

1National Institute of Neurological Disorders and Stroke (NINDS), Bethesda, MD, USA
2National Institutes of Health Center for Translational Therapeutics (NCTT), Rockville, MD, USA

Poster Title: Next-generation therapeutic avenues for neurological disease

Poster Abstract:

Parkinson’s disease (PD) is a complex neurodegenerative disorder that is poorly understood on the molecular level. Currently, there are no agents that can prevent or reverse the neural pathology of PD. To develop therapeutics that will aid millions living with PD, we must understand and modulate the molecular basis of the disease. With the exploration of how mitochondrial dysfunction is deeply intertwined in human disease, mitochondria health has emerged a major determinant of neuronal cell viability. Interestingly, mutations in PTEN-induced putative kinase 1 (Pink1) and the E3 ubiquitin ligase Parkin are causal factors in familial cases of PD. Pink1 has recently been shown to act as a sensor of mitochondrial dysfunction and is a key component of the quality control (QC) mechanism. Upon mitochondrial insult, Pink1 translocates to the outer membrane of damaged mitochondria where it recruits Parkin by an unknown mechanism. Activated Parkin then initiates a signaling cascade to specifically eliminate damaged mitochondria by an autophagic process (mitophagy). Cases of PD linked to mutant Pink1/Parkin highlight mitochondrial dysfunction as a core pathological mechanism that is likely to be relevant in sporadic forms of the disease.

My hypothesis is that mitochondrial QC is a useful point of intervention to prevent dopaminergic neuron loss, a hallmark of PD. To address the need for both drug discovery and target validation within mitochondrial QC, I have designed a battery of robust, HTS-validated assays (Z’>0.5) that target all aspects of the pathway. These assays that report Parkin translocation and mitophagy are being used for both large-scale functional genomics and chemical biology campaigns. I have executed a diverse array of whole-genome siRNA, miRNA, and cDNA screens in 384-well plates to elucidate genetic regulators of mitophagy and Parkin translocation. Using a high-content platform, my functional genomic screens have shed light on the links between proteasomal activation and early response to mitochondrial damage. Also, I have uncovered genes that may negatively regulate mitochondrial QC and are likely to be useful drug targets. To discover compounds that enhance the ability of neurons to remove damaged mitochondria, I constructed qHTS compatible (Z’>0.5) cell-based assays for Pink1 and Parkin expression in 1536-well plates. Overexpression of mitochondrial QC components has previously shown promise in animal models of PD.

I am currently screening the expression assays with a library of ~400,000 drug-like compounds (5-point titrations) to find those that increase Pink1 and Parkin expression. Screening hits are being followed with a multitude of diverse cell and biochemical assays for profiling compound activity. A major part of my drug discovery effort has been devoted to developing assays for high-content analysis that rapidly profile mitochondrial health. Overall, my small molecule discovery campaign aims to develop new therapeutic proof-of-concepts for PD and chemical tools to modulate mitochondrial QC.

Complete Poster (low resolution):

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