EARLY-ONSET PARKINSON'S DISEASE IS A MITOCHONDRIAL DISEASE: A NIGRAL MITOCHONDRIAL CYTOPATHY

Project: Research project

Project Details

Description

It is well-established that early-onset Parkinson’s disease (EOPD) can be caused by recessive mutations in PINK1 and PARK2 that result in loss of mitochondrial quality control (mitoQC). The mitochondrial kinase PINK1 has been shown to activate and recruit the E3 Ubiquitin ligase Parkin from the cytosol to specifically damaged mitochondria. PINK1 and Parkin then cooperate to label damaged organelles with phosphorylated poly-ubiquitin chains for selective disposal by autophagy. Since its discovery, enormous mechanistic insights have shown a broadly cytoprotective pathway with far-reaching implications and relevance for several human diseases. Technical advances and development of high-throughput imaging and biochemical assays have opened up unique possibilities to completely dissect mechanisms and identify genetic and pharmacological modifiers at different steps of a sequential process. From a genetics perspective, while mutations in PINK1 and Parkin are considered a common cause of familial EOPD, other genes are yet to be identified. Indeed, further known PD genes such as FBXO7, VPS35, and VPS13C have just been functionally linked to certain aspects of PINK1/Parkin-directed mitoQC. Building on this, the current application proposes to use a comprehensive approach to identify key genes involved in mitoQC and assess genetic variation at each locus for a role in PD.We will use an innovative, two-tiered miRNA/siRNA screen to identify both positive and negative regulators of mitoQC on a genome-wide level. Full datasets from High Content Imaging of Parkin recruitment to damaged mitochondria are already available from screens of both types of genomic libraries and will be supplemented with data from RNAseq. Here, we will capture changes in small miRNAs, mRNAs, and alternative splicing variants upon mitochondrial damage along the progression of the stress-induced PINK1/Parkin pathway. Existing genome-wide siRNA screens have identified more than 2,700 genes and 200 miRNAs that alter mitoQC efficiency, but have yet not been validated. To overlay the datasets and eventually nominate high confidence modifier genes, we have established a novel bioinformatics resource and filtering strategy that will allow us to efficiently narrow down the list of target genes. Using this innovative strategy, we have already identified a disease-relevant miRNA-target gene pair, namely, miR27a/b, which is upregulated upon mitochondrial damage and controls translation of the PINK1 mRNA in a negative feedback loop. Both PINK1 and miRNA27a/b will serve as positive controls in each assay and at every step of the analysis.Having identified a critical group of candidates, we will use whole-genome sequencing (WGS) in a clinically well-characterized series of 150 patients with EOPD (symptomatic onset

StatusFinished
Effective start/end date8/15/178/14/20

Funding

  • Congressionally Directed Medical Research Programs: $1,176,917.00

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