broadactivationoftheubiquitin–proteasomesystembyparkinis.ppt

Broad activation of the ubiquitin–proteasome system by Parkin is critical for mitophagy A review by Paul McCain Nickie C. Chan, Anna M. Salazar, Anh H. Pham, Michael J. Sweredoski, Natalie J. Kolawa1, Robert L.J. Graham, Sonja Hess, and David C. Chan Human Molecular Genetics, 2011, Vol. 20, No. 9, pgs. 1726-1737 Discussion Topics Experimental Background Focus of the Study SILAC Analysis Mitochondrial Membrane Degradation Conclusion Future Research Experimental Background Parkin is a Parkinson’s disease (PD) related protein. When mitochondria malfunction Parkin translocates from the cytosol in order to aid in degrading them via mitophagy. Parkin is an E3 ubiquitinase that attaches the protein ubiquitin to malfunctioning mitochondria in a chain linked fashion marking them for degradation. Two major pathways of Parkin mediated polyubiquitization and degradation are reported. The ubiquitin-proteasome system (UPS), which uses the K48-linked polyubiquitization of substrate proteins, whose malfunction would lead to an accumulation of misfolded proteins (Lewy bodies) The K63-linked polyubiquitization of mitochondrial proteins, which recruits ubiquitin adaptors of the autophagic machinery.(HDAC6 and p62/SQSTM1) What was the study’s focus? Key Concepts K48-mediated UPS pathway’s association with mitophagy 26S proteasome’s involvement in mitochondrial outer membrane protein degradation by the UPS UPS is a necessity of mitophagy and is activated prior UPS inhibition prevents mitophagic function This study was focused on better understanding the function of Parkin and the associated changes to the mitochondrial proteome in response to Parkin. SILAC 2 hours of treatment with CCCP depletes mitochondrial membrane potential in Parkin-expressing HeLa S3 clones. Parkin-dependent mitophagy results 2979 different protein groups identified. 1013 mitochondrial proteins Stable isotope labeling by amino acid culture analysis (Mass Spec Approach) SILAC Interpretation P