Identification of the ER-resident E3 ubiquitin ligase RNF145 as a novel LXR-regulated gene

• Published in: PloS one Vol. 12; no. 2; p. e0172721
• Main Authors: Cook, Emma C L, Nelson, Jessica K, Sorrentino, Vincenzo, Koenis, Duco, Moeton, Martina, Scheij, Saskia, Ottenhoff, Roelof, Bleijlevens, Boris, Loregger, Anke, Zelcer, Noam
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 23.02.2017; Public Library of Science (PLoS)
• Subjects: Animals; Biochemistry; Biology and Life Sciences; Biosynthesis; Cell Line; Cell lines; Cholesterol; Cholesterol - metabolism; Cloning; Endoplasmic Reticulum - metabolism; Fibroblasts; Gene expression; Gene Expression Regulation; Genetic aspects; Genetic regulation; Humans; Hydrocarbons, Fluorinated - pharmacology; Kinases; Laboratories; Ligands; Ligases; Lipid metabolism; Lipids; Lipoproteins; Liver; Liver - drug effects; Liver - metabolism; Liver X receptors; Liver X Receptors - genetics; Liver X Receptors - metabolism; Macrophages; Medicine and Health Sciences; Membrane Proteins - genetics; Membrane Proteins - metabolism; Metabolism; Mice; Mice, Knockout; Mutagenesis; Mutation; Plasmids; Promoter Regions, Genetic; Proteins; Receptors; Research and Analysis Methods; Rodents; Sterol regulatory element-binding protein; Sterols; Sulfonamides - pharmacology; Transcription; Transcription (Genetics); Transcription factors; Transcription, Genetic; Ubiquitin; Ubiquitin-protein ligase; Ubiquitin-Protein Ligases - metabolism; Ubiquitination; Yang, Cindy; United States > US; Switzerland; Netherlands
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0172721

Cellular cholesterol metabolism is subject to tight regulation to maintain adequate levels of this central lipid molecule. Herein, the sterol-responsive Liver X Receptors (LXRs) play an important role owing to their ability to reduce cellular cholesterol load. In this context, identifying the full set of LXR-regulated genes will contribute to our understanding of their role in cholesterol metabolism. Using global transcriptional analysis we report here the identification of RNF145 as an LXR-regulated target gene. We demonstrate that RNF145 is regulated by LXRs in both human and mouse primary cells and cell lines, and in vivo in mice. Regulation of RNF145 by LXR depends on a functional LXR-element in its proximal promotor. Consistent with LXR-dependent regulation of Rnf145 we show that regulation is lost in macrophages and fibroblasts from Lxrαβ(-/-) mice, and also in vivo in livers of Lxrα(-/-) mice treated with the LXR synthetic ligand T0901317. RNF145 is closely related to RNF139/TRC8, an E3 ligase implicated in control of SREBP processing. However, silencing of RNF145 in HepG2 or HeLa cells does not impair SREBP1/2 processing and sterol-responsive gene expression in these cells. Similar to TRC8, we demonstrate that RNF145 is localized to the ER and that it possesses intrinsic E3 ubiquitin ligase activity. In summary, we report the identification of RNF145 as an ER-resident E3 ubiquitin ligase that is transcriptionally controlled by LXR.