Parkinson's disease (PD) is a devastating disorder for which to date only symptomatic treatments exist. The causes remain enigmatic and thus therapeutics that halt or prevent PD are not available. The last few years have been extremely exciting due to the discovery of a novel mitochondrial quality control (mtQC) pathway by our laboratory and others. By now, this pathway links three parkinsonism associated genes, PINK1 PARKIN, and FBXO7, as well as the two major cellular dysfunctions involved in disease pathogenesis: mt dysfunction and impairment of degradation pathways. The mtQC pathway is thought to facilitate the elimination of dysfunctional organelles that would otherwise cause further cellular damage. However, (patho-) physiological relevant triggers of this pathway, particular in disease-relevant cells and in vivo are unclear. Upon accumulation of the kinase PINK1 specifically on damaged mitochondria, Parkin is recruited to catalyze differential ubiquitinations of mitochondrial substrates. However, Parkin's enzymatic functions, its E2 co-factors, the topologies of formed ubiquitin chains and their biological roles remain enigmatic. Given the recently resolved structure of Parkin and its 'closed'auto-inhibited conformation, we suggest that Parkin is sequentially activated to unleash its ubiquitin ligase functions. We have identified select E2 enzymes that regulate Parkin's activation and its enzymatic functions, excitingly through different and opposing mechanisms. Given that several therapeutic opportunities may exist along Parkin's activation cascade, we will perform structure-function analyses of this neuroprotective protein. Further, the accumulation of misfolded proteins in mitochondria may act as a physiological stimulus for PINK1 and Parkin activation. Strikingly, the induced mt- specific unfolded protein response (mtUPR) has very recently been described as a conserved longevity mechanism. We propose to elucidate the (in-) activation mechanisms of Parkin's functions on the structural, molecular, cellular, and organismal level. Therefore, we will use cutting-edge technologies and combine computational, functional biochemical and cell-biological with genetic methods in human iPSC-derived neurons and in vivo in C. elegans. Based on preliminary data, we hypothesize that Parkin is activated through the mtUPR, is regulated by bioenergetics and integrates with conserved aging pathways. On the molecular and structural level, Parkin is controlled by post-translational modifications, conformational rearrangements and by select E2 co-enzymes. Specifically, we will 1) unravel biological and molecular mechanism that (in)-activate Parkin in health and disease;2) determine Parkin's physiological E2 co-enzymes, their regulatory roles and contribution to PD;3) determine Parkin's activity(ies) and their interplay with bioenergetics and aging pathways. The proposed studies are relevant to fully appreciate the biological significance and potential of Parkin-directed mitochondrial quality control for disease intervention and to uncover important mechanistic insights that will provide the basis for rationale drug design.
This proposal is designed to study the enzymatic functions of the Parkinson's disease (PD) associated gene product Parkin and its protective role along the recently discovered mitochondrial quality control. Understanding the underlying biology, determining its significance and disease relevance in cell-based models and in vivo could lead to novel disease-modifying therapies for PD.
|Kim, Jaekwang; Fiesel, Fabienne C; Belmonte, Krystal C et al. (2016) miR-27a and miR-27b regulate autophagic clearance of damaged mitochondria by targeting PTEN-induced putative kinase 1 (PINK1). Mol Neurodegener 11:55|
|(2016) Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition). Autophagy 12:1-222|
|Fiesel, Fabienne C; Springer, Wolfdieter (2015) Disease relevance of phosphorylated ubiquitin (p-S65-Ub). Autophagy 11:2125-2126|
|Ogaki, Kotaro; Koga, Shunsuke; Heckman, Michael G et al. (2015) Mitochondrial targeting sequence variants of the CHCHD2 gene are a risk for Lewy body disorders. Neurology 85:2016-25|
|Lorenzo-Betancor, O; Ogaki, K; Soto-Ortolaza, A I et al. (2015) DNAJC13 p.Asn855Ser mutation screening in Parkinson's disease and pathologically confirmed Lewy body disease patients. Eur J Neurol 22:1323-5|
|Yue, M; Hinkle, K M; Davies, P et al. (2015) Progressive dopaminergic alterations and mitochondrial abnormalities in LRRK2 G2019S knock-in mice. Neurobiol Dis 78:172-95|
|Shi, J; Fung, G; Deng, H et al. (2015) NBR1 is dispensable for PARK2-mediated mitophagy regardless of the presence or absence of SQSTM1. Cell Death Dis 6:e1943|
|Caulfield, Thomas R; Fiesel, Fabienne C; Springer, Wolfdieter (2015) Activation of the E3 ubiquitin ligase Parkin. Biochem Soc Trans 43:269-74|
|Fiesel, Fabienne C; Ando, Maya; Hudec, Roman et al. (2015) (Patho-)physiological relevance of PINK1-dependent ubiquitin phosphorylation. EMBO Rep 16:1114-30|
|Fiesel, Fabienne C; Caulfield, Thomas R; Moussaud-LamodiÃ¨re, Elisabeth L et al. (2015) Structural and Functional Impact of Parkinson Disease-Associated Mutations in the E3 Ubiquitin Ligase Parkin. Hum Mutat 36:774-86|
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