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Enhanced O-GlcNAcylation Mediates Cytoprotection under Proteasome Impairment by Promoting Proteasome Turnover in Cancer Cells.

iScience (2020-07-08)
Eiichi Hashimoto, Shota Okuno, Shoshiro Hirayama, Yoshiyuki Arata, Tsuyoshi Goto, Hidetaka Kosako, Jun Hamazaki, Shigeo Murata
ABSTRACT

The proteasome is a therapeutic target in cancer, but resistance to proteasome inhibitors often develops owing to the induction of compensatory pathways. Through a genome-wide siRNA screen combined with RNA sequencing analysis, we identified hexokinase and downstream O-GlcNAcylation as cell survival factors under proteasome impairment. The inhibition of O-GlcNAcylation synergistically induced massive cell death in combination with proteasome inhibition. We further demonstrated that O-GlcNAcylation was indispensable for maintaining proteasome activity by enhancing biogenesis as well as proteasome degradation in a manner independent of Nrf1, a well-known compensatory transcription factor that upregulates proteasome gene expression. Our results identify a pathway that maintains proteasome function under proteasome impairment, providing potential targets for cancer therapy.