Cholesterol homeostasis is maintained through concerted action of the SREBPs and LXRs. Here, we report that RNF145, a previously uncharacterized ER membrane ubiquitin ligase, participates in crosstalk between these critical signaling pathways. RNF145 expression is induced in response to LXR activation and high-cholesterol diet feeding. Transduction of RNF145 into mouse liver inhibits the expression of genes involved in cholesterol biosynthesis and reduces plasma cholesterol levels. Conversely, acute suppression of RNF145 via shRNA-mediated knockdown, or chronic inactivation of RNF145 by genetic deletion, potentiates the expression of cholesterol biosynthetic genes and increases cholesterol levels both in liver and plasma. Mechanistic studies show that RNF145 triggers ubiquitination of SCAP on lysine residues within a cytoplasmic loop essential for COPII binding, potentially inhibiting its transport to Golgi and subsequent processing of SREBP-2. These findings define an additional mechanism linking hepatic sterol levels to the reciprocal actions of the SREBP-2 and LXR pathways.
|State||Published - Oct 25 2017|
Bibliographical noteFunding Information:
We are grateful to Dr. Peter Espenshade (Johns Hopkins) for the gift of the SCAP-deficient HEK293 cells. We thank Dr. Steven Bensinger, Dr. Simon Beaven, and members of the Tontonoz Laboratory and the UCLA Atherosclerosis Research Unit for useful discussions and technical support. This work was supported by NIH grants HL030568 and DK063491 (to PT) and American Heart Association Scientist Development Grant 16SDG31180008 (to LZ).
© Zhang et al.
ASJC Scopus subject areas
- Neuroscience (all)
- Biochemistry, Genetics and Molecular Biology (all)
- Immunology and Microbiology (all)