Modulation of SQSTM1/p62 activity by N-terminal arginylation of the endoplasmic reticulum chaperone HSPA5/GRP78/BiP

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Title
Modulation of SQSTM1/p62 activity by N-terminal arginylation of the endoplasmic reticulum chaperone HSPA5/GRP78/BiP
Author(s)
Hyunjoo Cha; Ji-Eun Yu; Su Hyun Lee; Jung Gi Kim; K S Sung; Joonsung Hwang; Y D Yoo; Y J Lee; S T Kim; D H Lee; A Ciechanover; Bo Yeon Kim; Y T Kwon
Bibliographic Citation
Autophagy, vol. 12, no. 2, pp. 426-428
Publication Year
2016
Abstract
The N-end rule pathway is a proteolytic system, in which single N-terminal residues act as a determinant of a class of degrons, called N-degrons. In the ubiquitin (Ub)-proteasome system, specific recognition components, called N-recognins, recognize N-degrons and accelerate polyubiquitination and proteasomal degradation of the substrates. In this study, we show that the pathway regulates the activity of the macroautophagic receptor SQSTM1/p62 (sequestosome 1) through N-terminal arginylation (Nt-arginylation) of endoplasmic reticulum (ER)-residing molecular chaperones, including HSPA5/GRP78/BiP, CALR (calreticulin), and PDI (protein disulfide isomerase). The arginylation is co-induced with macroautophagy (hereafter autophagy) as part of innate immunity to cytosolic DNA and when misfolded proteins accumulate under proteasomal inhibition. Following cytosolic relocalization and arginylation, Nt-arginylated HSPA5 (R-HSPA5) is targeted to autophagosomes and degraded by lysosomal hydrolases through the interaction of its N-terminal Arg (Nt-Arg) with ZZ domain of SQSTM1. Upon binding to Nt-Arg, SQSTM1 undergoes a conformational change, which promotes SQSTM1 self-polymerization and interaction with LC3, leading to SQSTM1 targeting to autophagosomes. Cargoes of R-HSPA5 include cytosolic misfolded proteins destined to be degraded through autophagy. Here, we discuss the mechanisms by which the N-end rule pathway regulates SQSTM1-dependent selective autophagy.
Keyword
ATE1 R-transferaseN-end rule pathwayprotein arginylationprotein quality controlproteolysis
ISSN
1554-8627
Publisher
T&F (Taylor & Francis)
DOI
http://dx.doi.org/10.1080/15548627.2015.1126047
Type
Article
Appears in Collections:
Ochang Branch Institute > Anticancer Agent Research Center > 1. Journal Articles
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