The E3 ubiquitin ligase STUB1 attenuates cell senescence by promoting the ubiquitination and degradation of the core circadian regulator BMAL1

Abstract

Cell senescence is one of the most important processes determining cell fate and is involved in many pathophysiological conditions, including cancer, neurodegenerative diseases, and other aging-associated diseases. It has recently been discovered that the E3 ubiquitin ligase STIP1 homology and U-box–containing protein 1 (STUB1 or CHIP) is up-regulated during the senescence of human fibroblasts and modulates cell senescence. However, the molecular mechanism underlying STUB1-controlled senescence is not clear. Here, using affinity purification and MS-based analysis, we discovered that STUB1 binds to brain and muscle ARNT-like 1 (BMAL1, also called aryl hydrocarbon receptor nuclear translocator–like protein 1 (ARNTL)). Through biochemical experiments, we confirmed the STUB1-BMAL1 interaction, identified their interaction domains, and revealed that STUB1 overexpression down-regulates BMAL1 protein levels through STUB1's enzymatic activity and that STUB1 knockdown increases BMAL1 levels. Further experiments disclosed that STUB1 enhances BMAL1 degradation, which is abolished upon proteasome inhibition. Moreover, we found that STUB1 promotes the formation of Lys-48–linked polyubiquitin chains on BMAL1, facilitating its proteasomal degradation. Interestingly, we also discovered that oxidative stress promotes STUB1 nuclear translocation and enhances its co-localization with BMAL1. STUB1 expression attenuates hydrogen peroxide–induced cell senescence, indicated by a reduced signal in senescence-associated β-gal staining and decreased protein levels of two cell senescence markers, p53 and p21. BMAL1 knockdown diminishes this effect, and BMAL1 overexpression abolishes STUB1's effect on cell senescence. In summary, the results of our work reveal that the E3 ubiquitin ligase STUB1 ubiquitinates and degrades its substrate BMAL1 and thereby alleviates hydrogen peroxide–induced cell senescence.

Data-independent acquisition method for ubiquitinome analysis reveals regulation of circadian biology

“…57 ), exemplified by the ubiquitin-dependent spatiotemporal regulation of CRY proteins, the major negative clock regulators 58 . Several studies have provided insights into ubiquitin-dependent events modulating core clock proteins and their effects [59][60][61] . Given the unexpected degree of phosphorylation-mediated signaling temporally regulated in vivo 52 , we wondered if ubiquitination shows similar oscillations.…”

Identification of a circadian gene signature that predicts overall survival in lung adenocarcinoma

“…The proteasome pathway was enriched in the high-risk group. Recent studies have also confirmed that some ubiquitin ligases participate in the degradation of core circadian clock genes through the ubiquitin-proteasome pathway, thereby controlling the biological functions of cells, including cell senescence ( Chen et al, 2018 ; Ullah et al, 2020 ). This cross-talk between circadian clock genes and the ubiquitin-proteasome pathway may be related to the prognosis of LUAD.…”

Data-independent acquisition method for ubiquitinome analysis reveals regulation of circadian biology

“…Ubiquitination plays a pivotal role in the core clock machinery (reviewed in 54 ), exemplified by the ubiquitin-dependent spatiotemporal regulation of CRY proteins, the major negative clock regulators 55 . Focused studies have provided insights into several ubiquitin-dependent events modulating core clock proteins and their effects 56–58 . Given the unexpected degree of phosphorylation-mediated signaling temporally regulated in vivo 51 , we wondered if ubiquitination shows similar oscillations.…”