A novel role for CRTC2 in hepatic cholesterol synthesis through SREBP-2

Yujie Li, Yongfeng Song, Meng Zhao, Yanjing Guo, Chunxiao Yu, Wenbin Chen, Shanshan Shao, Chao Xu, Xinli Zhou, Lifang Zhao, Zhenhai Zhang, Tao Bo, Yu Xia, Christopher G. Proud, Xuemin Wang, Li Wang, Jiajun Zhao, Ling Gao

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Cholesterol synthesis is regulated by the transcription factor sterol regulatory element binding protein 2 (SREBP-2) and its target gene 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), which is the rate-limiting enzyme in cholesterol synthesis. Cyclic adenosine monophosphate–responsive element (CRE) binding protein–regulated transcription coactivator (CRTC) 2 is the master regulator of glucose metabolism. However, the effect of CRTC2 on cholesterol and its potential molecular mechanism remain unclear. Here, we demonstrated that CRTC2 expression and liver cholesterol content were increased in patients with high serum cholesterol levels who underwent resection of liver hemangiomas, as well as in mice fed a 4% cholesterol diet. Mice with adenovirus-mediated CRTC2 overexpression also showed elevated lipid levels in both serum and liver tissues. Intriguingly, hepatic de novo cholesterol synthesis was markedly increased under these conditions. In contrast, CRTC2 ablation in mice fed a 4% cholesterol diet (18 weeks) showed decreased lipid levels in serum and liver tissues compared with those in littermate wild-type mice. The expression of lipogenic genes (SREBP-2 and HMGCR) was consistent with hepatic CRTC2 levels. In vivo imaging showed enhanced adenovirus-mediated HMGCR-luciferase activity in adenovirus-mediated CRTC2 mouse livers; however, the activity was attenuated after mutation of CRE or sterol regulatory element sequences in the HMGCR reporter construct. The effect of CRTC2 on HMGCR in mouse livers was alleviated upon SREBP-2 knockdown. CRTC2 modulated SREBP-2 transcription by CRE binding protein, which recognizes the half-site CRE sequence in the SREBP-2 promoter. CRTC2 reduced the nuclear protein expression of forkhead box O1 and subsequently increased SREBP-2 transcription by binding insulin response element 1, rather than insulin response element 2, in the SREBP-2 promoter. Conclusion: CRTC2 regulates the transcription of SREBP-2 by interfering with the recognition of insulin response element 1 in the SREBP-2 promoter by forkhead box O1, thus inducing SREBP-2/HMGCR signaling and subsequently facilitating hepatic cholesterol synthesis. (Hepatology 2017;66:481–497).

Original languageEnglish
Pages (from-to)481-497
Number of pages17
JournalHepatology
Volume66
Issue number2
DOIs
Publication statusPublished - 1 Aug 2017

ASJC Scopus subject areas

  • Hepatology

Cite this

Li, Y., Song, Y., Zhao, M., Guo, Y., Yu, C., Chen, W., ... Gao, L. (2017). A novel role for CRTC2 in hepatic cholesterol synthesis through SREBP-2. Hepatology, 66(2), 481-497. https://doi.org/10.1002/hep.29206