The ubiquitin-specific protease USP8 directly deubiquitinates SQSTM1/p62 to suppress its autophagic activity

Abstract

SQSTM1/p62 (sequestosome 1) is a critical macroautophagy/autophagy receptor that promotes the formation and degradation of ubiquitinated aggregates. SQSTM1 can be modified by ubiquitination, and this modification modulates its autophagic activity. However, the molecular mechanisms underpinning its reversible deubiquitination have never been described. Here we report that USP8 (ubiquitin specific peptidase 8) directly interacted with and deubiquitinated SQSTM1. USP8 preferentially removed the lysine 11 (K11)-linked ubiquitin chains from SQSTM1. Moreover, USP8 deubiquitinated SQSTM1 principally at K420 within its ubiquitinassociation (UBA) domain. Finally, USP8 inhibited SQSTM1 degradation and autophagic influx in cells with wildtype SQSTM1, but not its mutant with substitution of K420 with an arginine. Taken together, USP8 acts as a negative regulator of autophagy by deubiquitinating SQSTM1 at K420.

Ubiquitin-specific protease 8 (USP8/UBPy): a prototypic multidomain deubiquitinating enzyme with pleiotropic functions

“…Unexpectedly, USP8 knock-down in HeLa cells resulted in deregulation of the autophagy flux [73]. This is consistent with recent findings suggesting that USP8 acts as a negative regulator of autophagy by deubiquitinating SQSTM1/p62 at K420 located in the UBA domain [74]. Interestingly, USP8 was also found to interact with NBR1 in a yeast two-hybrid screen [75].…”

The Protective Effect of Cyanidin‐3‐Glucoside on Myocardial Ischemia‐Reperfusion Injury through Ferroptosis

“…USP13 knockdown increases p-tau ubiquitination via the 20S proteasome and p-tau clearance via autophagy [ 25 ]. USP8 directly deubiquitinates SQSTM1/p62 and blocks autophagy [ 26 ]. It is noteworthy that USP19 influences the ubiquitination of Beclin1, hence accelerating the production of autophagosome.…”

Beyond K48 and K63: non-canonical protein ubiquitination

“…There is ample evidence supporting the involvement of K11-linked ubiquitination in the control of the degradation of mitochondrial antiviral signaling protein (MAVS) after RNA virus infection [ 63 ] and degradation of cGAS once Zika virus NS1 protein recruits USP8 to remove K11-linked chains from caspase-1 [ 64 ]. USP8 has also been shown to preferentially remove K11-linked chains preventing the autophagic degradation of SQSTM1/p62 (sequestosome 1), a critical autophagy receptor that promotes the formation and degradation of ubiquitinated aggregates [ 65 ].…”