The N-end rule pathway regulates ER stress-induced clusterin release to the cytosol where it directs misfolded proteins for degradation

Sandeep Satapathy; Holly Walker; James Brown; Yann Gambin; Mark R Wilson

doi:10.1016/j.celrep.2023.113059

The N-end rule pathway regulates ER stress-induced clusterin release to the cytosol where it directs misfolded proteins for degradation

Cell Rep. 2023 Sep 26;42(9):113059. doi: 10.1016/j.celrep.2023.113059. Epub 2023 Sep 1.

Authors

Sandeep Satapathy¹, Holly Walker², James Brown³, Yann Gambin³, Mark R Wilson⁴

Affiliations

¹ The Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA; School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; Molecular Horizons Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.
² School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; Molecular Horizons Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.
³ EMBL Australia Node in Single Molecule Science, and School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
⁴ School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; Molecular Horizons Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia. Electronic address: mrw@uow.edu.au.

PMID: 37660295
DOI: 10.1016/j.celrep.2023.113059

Abstract

Previous work suggests that cell stress induces release of the normally secreted chaperone clusterin (CLU) into the cytosol. We analyzed the localization of CLU in healthy and stressed cells, the mechanism of its cytosolic release, and its interactions with cytosolic misfolded proteins. Key results of this study are the following: (1) full-length CLU is released to the cytosol during stress, (2) the CLU N-terminal D1 residue is recognized by the N-end rule pathway and together with the enzyme ATE1 is essential for cytosolic release, (3) CLU can form stable complexes with cytosolic misfolded proteins and direct them to the proteasome and autophagosomes, and (4) cytosolic CLU protects cells from hypoxic stress and the cytosolic overexpression of an aggregation-prone protein. Collectively, the results suggest that enhanced cytosolic release of CLU is a stress response that can inhibit the toxicity of misfolded proteins and facilitate their targeted degradation via both autophagy and the proteasome.

Keywords: CP: Cell biology; N-End Rule Pathway; autophagy; clusterin; cytoprotection; cytosolic release; intracellular proteostasis; proteasome.