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Proc Natl Acad Sci U S A. 2016 Nov 22;113(47):E7490-E7499. Epub 2016 Oct 17.

p62- and ubiquitin-dependent stress-induced autophagy of the mammalian 26S proteasome.

Author information

1
Technion Integrated Cancer Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109602, Israel.
2
Smoler Proteomic Center and Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
3
Protein Metabolism Medical Research Center and Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul 03080, Korea.
4
Technion Integrated Cancer Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109602, Israel; aaroncie@technion.ac.il.

Abstract

The ubiquitin-proteasome system and autophagy are the two main proteolytic systems involved in, among other functions, the maintenance of cell integrity by eliminating misfolded and damaged proteins and organelles. Both systems remove their targets after their conjugation with ubiquitin. An interesting, yet incompletely understood problem relates to the fate of the components of the two systems. Here we provide evidence that amino acid starvation enhances polyubiquitination on specific sites of the proteasome, a modification essential for its targeting to the autophagic machinery. The uptake of the ubiquitinated proteasome is mediated by its interaction with the ubiquitin-associated domain of p62/SQSTM1, a process that also requires interaction with LC3. Importantly, deletion of the PB1 domain of p62, which is important for the targeting of ubiquitinated substrates to the proteasome, has no effect on stress-induced autophagy of this proteolytic machinery, suggesting that the domain of p62 that binds to the proteasome determines the function of p62 in either targeting substrates to the proteasome or targeting the proteasome to autophagy.

KEYWORDS:

autophagy; degradation; proteasome; ubiquitin

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PMID:
27791183
PMCID:
PMC5127335
DOI:
10.1073/pnas.1615455113
[Indexed for MEDLINE]
Free PMC Article

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