IRE1 prevents hepatic steatosis by processing and promoting the degradation of select microRNAs

Jie Mei Wang, Yining Qiu, Zhao Yang, Hyunbae Kim, Qingwen Qian, Qinghua Sun, Chunbin Zhang, Lei Yin, Deyu Fang, Sung Hong Back, Randal J. Kaufman, Ling Yang, Kezhong Zhang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Obesity or a high-fat diet represses the endoribonuclease activity of inositol-requiring enzyme 1 (IRE1), a transducer of the unfolded protein response (UPR) in cells under endoplasmic reticulum (ER) stress. An impaired UPR is associated with hepatic steatosis and nonalcoholic fatty liver disease (NAFLD), which is caused by lipid accumulation in the liver. We found that IRE1 was critical to maintaining lipid homeostasis in the liver by repressing the biogenesis of microRNAs (miRNAs) that regulate lipid mobilization. In mice fed normal chow, the endoribonuclease function of IRE1 processed a subset of precursor miRNAs in the liver, including those of the miR-200 and miR-34 families, such that IRE1 promoted their degradation through the process of regulated IRE1-dependent decay (RIDD). A high-fat diet in mice or hepatic steatosis in patients was associated with the S-nitrosylation of IRE1 and inactivation of its endoribonuclease activity. This resulted in an increased abundance of these miRNA families in the liver and, consequently, a decreased abundance of their targets, which included peroxisome proliferator–activated receptor (PPAR) and the deacetylase sirtuin 1 (SIRT1), regulators of fatty acid oxidation and triglyceride lipolysis. IRE1 deficiency exacerbated hepatic steatosis in mice. The abundance of the miR-200 and miR-34 families was also increased in cultured, lipid-overloaded hepatocytes and in the livers of patients with hepatic steatosis. Our findings reveal a mechanism by which IRE1 maintains lipid homeostasis through its regulation of miRNAs, a regulatory pathway distinct from the canonical IRE1-UPR pathway under acute ER stress.

Original languageEnglish (US)
Article numbereaao4617
JournalScience Signaling
Volume11
Issue number530
DOIs
StatePublished - May 15 2018

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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