TY - JOUR TI - The sterol-responsive RNF145 E3 ubiquitin ligase mediates the degradation of HMG-CoA reductase together with gp78 and Hrd1 AU - Menzies, Sam A AU - Volkmar, Norbert AU - van den Boomen, Dick JH AU - Timms, Richard T AU - Dickson, Anna S AU - Nathan, James A AU - Lehner, Paul J A2 - Dikic, Ivan A2 - Harper, Wade A2 - Hampton, Randy Y VL - 7 PY - 2018 DA - 2018/12/13 SP - e40009 C1 - eLife 2018;7:e40009 DO - 10.7554/eLife.40009 UR - https://doi.org/10.7554/eLife.40009 AB - Mammalian HMG-CoA reductase (HMGCR), the rate-limiting enzyme of the cholesterol biosynthetic pathway and the therapeutic target of statins, is post-transcriptionally regulated by sterol-accelerated degradation. Under cholesterol-replete conditions, HMGCR is ubiquitinated and degraded, but the identity of the E3 ubiquitin ligase(s) responsible for mammalian HMGCR turnover remains controversial. Using systematic, unbiased CRISPR/Cas9 genome-wide screens with a sterol-sensitive endogenous HMGCR reporter, we comprehensively map the E3 ligase landscape required for sterol-accelerated HMGCR degradation. We find that RNF145 and gp78 independently co-ordinate HMGCR ubiquitination and degradation. RNF145, a sterol-responsive ER-resident E3 ligase, is unstable but accumulates following sterol depletion. Sterol addition triggers RNF145 recruitment to HMGCR via Insigs, promoting HMGCR ubiquitination and proteasome-mediated degradation. In the absence of both RNF145 and gp78, Hrd1, a third UBE2G2-dependent E3 ligase, partially regulates HMGCR activity. Our findings reveal a critical role for the sterol-responsive RNF145 in HMGCR regulation and elucidate the complexity of sterol-accelerated HMGCR degradation. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter). KW - RNF145 KW - gp78 KW - HMGCR KW - cholesterol KW - ER associated degradation KW - E3 ubiquitin ligase JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -