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MicroRNAs (miRNAs) constitute a growing class of non-coding RNAs that are thought to regulate gene expression by translational repression. Several miRNAs in animals exhibit tissue-specific or developmental-stage-specific expression, indicating that they could play important roles in many biological processes. To study the role of miRNAs in pancreatic endocrine cells we cloned and identified a novel, evolutionarily conserved and islet-specific miRNA (miR-375). Here we show that overexpression of miR-375 suppressed glucose-induced insulin secretion, and conversely, inhibition of endogenous miR-375 function enhanced insulin secretion. The mechanism by which secretion is modified by miR-375 is independent of changes in glucose metabolism or intracellular Ca2+-signalling but correlated with a direct effect on insulin exocytosis. Myotrophin (Mtpn) was predicted to be and validated as a target of miR-375. Inhibition of Mtpn by small interfering (si)RNA mimicked the effects of miR-375 on glucose-stimulated insulin secretion and exocytosis. Thus, miR-375 is a regulator of insulin secretion and may thereby constitute a novel pharmacological target for the treatment of diabetes.

Original publication

DOI

10.1038/nature03076

Type

Journal article

Journal

Nature

Publication Date

11/11/2004

Volume

432

Pages

226 - 230

Keywords

Animals, Calcium Signaling, Cell Line, Cloning, Molecular, Diabetes Mellitus, Exocytosis, Gene Expression, Gene Silencing, Genetic Therapy, Glucose, Insulin, Insulin Secretion, Intercellular Signaling Peptides and Proteins, Islets of Langerhans, Mice, MicroRNAs, Organ Specificity, Potassium Chloride, Substrate Specificity, Tolbutamide