Journal of Cell Biology, Published March 25, 2013, doi/10.1083/jcb.201209098
The scaffold protein EPG-7 links cargo–receptor complexes with the autophagic assembly machinery
Long Lin,1,2,3 Peiguo Yang,1 Xinxin Huang,3 Hui Zhang,1 Qun Lu,3 and Hong Zhang1
1State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
2College of Life Sciences, Beijing Normal University, Beijing 100875, China
3National Institute of Biological Sciences, Beijing 102206, China
Abstrct
The mechanism by which protein aggregates are selectively degraded by autophagy is poorly understood. Previous studies show that a family of Atg8-interacting proteins function as receptors linking specific cargoes to the autophagic machinery. Here we demonstrate that during Caenorhabditis elegans embryogenesis, epg-7 functions as a scaffold protein mediating autophagic degradation of several protein aggregates, including aggregates of the p62 homologue SQST-1, but has little effect on other autophagy-regulated processes. EPG-7 self-oligomerizes and is degraded by autophagy independently of SQST-1. SQST-1 directly interacts with EPG-7 and colocalizes with EPG-7 aggregates in autophagy mutants. Mutations in epg-7 impair association of SQST-1 aggregates with LGG-1/Atg8 puncta. EPG-7 interacts with multiple ATG proteins and colocalizes with ATG-9 puncta in various autophagy mutants. Unlike core autophagy genes, epg-7 is dispensable for starvation-induced autophagic degradation of substrate aggregates. Our results indicate that under physiological conditions a scaffold protein endows cargo specificity and also elevates degradation efficiency by linking the cargo–receptor complex with the autophagic machinery.
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全文链接：http://jcb.rupress.org/content/early/2013/03/19/jcb.201209098.full.pdf+html
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