MIR192 upregulates GLP-1 receptor and rescues statin-induced impairment of insulin secretion

Abstract

Statins are a commonly prescribed cholesterol-lowering drug class that can increase the risk of new-onset diabetes (NOD). The underlying molecular mechanisms have yet to be fully elucidated. We aimed to identify molecular factors associated with differential susceptibility to NOD and determine their effects on β-cell function. Human induced pluripotent stem cells (iPSCs) were generated from statin users identified through the Kaiser Permanente of Northern California electronic health records who developed NOD or substantial worsening of fasting glucose following statin initiation (susceptible cases) or maintained stable fasting glucose levels (resistant controls). RNA-seq was performed on iPSCs incubated with atorvastatin or simvastatin. Functional studies were conducted in a rat insulinoma cell line (INS-1) and in primary mouse islets using miR-192-5p mimics, inhibitors, luciferase reporter assays, glucose-stimulated insulin secretion (GSIS) assays, ex vivo perifusion, and in vivo glucose tolerance studies. RNA-seq identified the long non-coding RNA MIR194-2HG , which contains the microRNA gene MIR192 , as a top candidate transcript exhibiting opposite statin-induced regulation in NOD susceptible and resistant individuals. The mature microRNA miR-192-5p was predicted to bind the 3’ UTR of the human glucagon- like peptide 1 (GLP-1) receptor ( GLP1R ) transcript. Overexpression of miR-192-5p increased Glp1r transcript (1.41-fold) and GLP1R protein (1.51-fold) levels in INS-1 cells and enhanced activity of a luciferase reporter containing the human GLP1R 3′ UTR (1.44-fold). This unexpected upregulation was consistent with a non-canonical miRNA-ribonucleoprotein mechanism that promotes GLP1R expression. miR-192-5p enhanced glucose-stimulated insulin secretion (GSIS) in response to GLP1R agonists (1.64–1.81-fold) and rescued simvastatin-induced GSIS impairment in INS-1 cells. Islets isolated from wild-type mice treated with an AAV8 vector expressing Mir192 exhibited enhanced GLP-1 potentiated GSIS during perifusion ex vivo. These effects were absent in double incretin receptor knockout (DIRKO) mouse islets. Lastly, miR-192 expression improved glycemic response to intraperitoneal glucose challenge and the GLP1R agonist liraglutide in mice fed a high-fat diet. miR-192-5p is a regulator of β-cell GLP1R expression and incretin-enhanced insulin secretion. These findings implicate miR-192-5p in statin-induced impairment of GSIS by modulating GLP1R, potentially contributing to the susceptibility to NOD in statin users.