Dysregulation of microRNA-770-5p influences pancreatic-β-cell function by targeting TP53 regulated inhibitor of apoptosis 1 in gestational diabetes mellitus

Y.-L. Zhang, X.-Q. Chen

Department of Obstetrics, Huai’an First People’s Hospital/The Affiliated Huai’an No. 1 People’s Hospital of Nanjing Medical University, Huai’an, China. chenxiaoqin19641@163.com

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• Metabolism

OBJECTIVE: The purpose of this study was to investigate the role of microRNA-770-5p (miR-770-5p) in gestational diabetes mellitus (GDM).
MATERIALS AND METHODS: In the present study, the expression levels of miR-770-5p in the peripheral blood from GDM women and healthy women were investigated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The relationship between TP53 regulated inhibitor of apoptosis 1 (TRIAP1) and miR-770-5p was determined using dual-luciferase reporter assay. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry were used to detect pancreatic β-cell proliferation and apoptosis. Enzyme-linked immunosorbent assay (ELISA) was used to measure total insulin content and insulin secretion.
RESULTS: Our data indicated that miR-770-5p was up-regulated in GDM patients. TRIAP1 was a direct target of miR-770-5p and it was down-regulated in GDM patients. Besides, miR-770-5p negatively regulated the expression of TRIAP1 in INS-1 cells. Then, we explored the effects of miR-770-5p down-regulation on the insulin secretion of pancreatic β-cells, and the results showed that miR-770-5p inhibitor promoted the generation of insulin secretion or total insulin content in INS-1 cells, while these effects were significantly inhibited by TRIAP1-siRNA. Moreover, we found that miR-770-5p inhibitor enhanced INS-1 cell proliferation and suppressed cell apoptosis, whereas these effects were eliminated by TRIAP1-siRNA. Accordingly, miR-770-5p inhibitor decreased the expression of Bax, apoptotic peptidase activating factor 1 (APAF1) and increased Bcl-2 level in INS1 cells. These results were all reversed by TRIAP1-siRNA.
CONCLUSIONS: The data demonstrated that miR-770-5p was a vital regulator in pancreatic β-cell proliferation, apoptosis and insulin secretion by targeting TRIAP1, and dysregulation of miR-770-5p resulted in the development of GDM via APAF1 signaling pathway.

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