Event Date:
Thursday, November 19, 2020 - 4:00pm to 5:00pm
Wade Harper, Ph.D., Professor of Cell Biology, Harvard Medical School
Abstract: The ubiquitin ligase Parkin, protein kinase PINK1, USP30 deubiquitylase, and p97 segregase function together to regulate turnover of damaged mitochondria via mitophagy, but our mechanistic understanding in neurons is limited. We have used induced neurons (iNeurons) derived from embryonic stem cells together with quantitative proteomics to reveal the dynamics and specificity of Parkin-dependent mitochondrial outer membrane protein ubiquitylation under endogenous expression conditions. Targets showing elevated ubiquitylation in USP30-/- iNeurons are concentrated in components of the mitochondrial translocon, and the ubiquitylation kinetics of the vast majority of Parkin targets are unaffected, correlating with a modest kinetic acceleration in accumulation of pS65-Ub and mitophagic flux upon mitochondrial depolarization without USP30. Basally, ubiquitylated translocon import substrates accumulate, suggesting a quality control function for USP30. p97 was dispensable for Parkin-dependent mitochondrial ubiquitylation in iNeurons. We will discuss how the biochemical landscape of Parkin action of mitochondria promotes capture by the autophagy system.
Publications
Ordureau A, Paulo JA, Zhang J, An H, Swatek KN, Cannon JR, Wan Q, Komander D, Harper JW. Global Landscape and Dynamics of Parkin and USP30-Dependent Ubiquitylomes in iNeurons during Mitophagic Signaling. Mol Cell. 2020 Mar 5;77(5):1124-1142.e10. doi: 10.1016/j.molcel.2019.11.013. PMID: 32142685; PMCID: PMC7098486.
Heo JM, Harper NJ, Paulo JA, Li M, Xu Q, Coughlin M, Elledge SJ, Harper JW. Integrated proteogenetic analysis reveals the landscape of a mitochondrial-autophagosome synapse during PARK2-dependent mitophagy. Sci Adv. 2019 Nov 6;5(11):eaay4624. doi: 10.1126/sciadv.aay4624. PMID: 31723608; PMCID: PMC6834391.
Ordureau A, Paulo JA, Zhang W, Ahfeldt T, Zhang J, Cohn EF, Hou Z, Heo JM, Rubin LL, Sidhu SS, Gygi SP, Harper JW. Dynamics of PARKIN-Dependent Mitochondrial Ubiquitylation in Induced Neurons and Model Systems Revealed by Digital Snapshot Proteomics. Mol Cell. 2018 Apr 19;70(2):211-227.e8. doi: 10.1016/j.molcel.2018.03.012. Epub 2018 Apr 12. PMID: 29656925; PMCID: PMC5910199.