ESPE Abstracts

Background: Type 1 diabetes is characterised by destruction of islet β cell by autoimmune insulitis and islet cell apoptosis. This study analysed the microRNA 125b how to regulate pancreatic β-cells dysfunction, aiming to elucidate the association between miRNA125b and type 1 diabetes.

Objective and hypotheses: Recent study indicate miRNA may have role in the development of type 1 diabetes, so this study analyse the miRNA expression profile in the pancreas of type 1 diabetes model NOD mouse, By microarray analysis, clustering analysis indicate a different miRNA profile in insulitis. miR-125b have significant alteration, which is validated by qRT-PCR. we investigated the influence of miR-125b in pancreatic β-cell dysfunction.

Method: In vitro study, we established the PA (palmitic acid) induced apoptosis model in NIT-1 islet cell line. we found mir-125b expression upregulated during apoptosis. After transient transfection with mimics and inhibitor of mir-125b in NIT-1 cell cells, we found mir-125b inhibit Bak1 expression, then subsequently downregulate Cytochrome C and caspase-3 expression, contribute to its inhibition effects on apoptosis. The bioinformatic analysis show the Bak1 is predict target of miR-125b, dual luciferase reporter assay preliminarily validate Bak1 is target gene of miR-125b. We studied the effect of miR-125b on proliferation?apoptosis and insulin secretion in β-cells through flow cytometry, CCK8 assay and ELISA, discovered the molecular mechanism behind these phenomena by RT-PCR, Western blot and luciferase reporter gene technology.

Results: In addition to low viability and increased apoptosis rate, prolonged exposure of the β-cell lines to palmitate caused a dose-dependent decrease of miR-125b.Over-expression miR-125b dramatically suppressed the expression of Bak1 and inhibit cells apoptosis. High miR-125b level also promoted insulin secretion by increasing cell viability. In diabetic mice, low expression level of miR-125b was detected, indicated that miR-125b may be involved in mechanisms of type 1 diabetes.

Conclusion: Our findings suggest that miR-125b participate in pancreatic β-cell dysfunction and involve in the molecular mechanism of type 1 diabetes, maybe as a novel target for the treatment of this disease.