Role Of Transcription Factor NFATc3in Pancreatic Beta Cells Proliferation And Function

Objective:This study was aimed to investigate the role and mechanism of transcription factor NFATc3in regulating pancreatic beta cells proliferation and function.Methods:RT-qPCR, Western Blot and immunocytochemistry were used to determine NFATc3gene expression levels in mouse pancreatic islets of high fat diet (HFD) fed mice. Adenovirus-NFATc3and control Adenovirus-GFP were used for overexpression NFATc3in MIN6cells. BrdU labeling and staining was used to test MIN6cells proliferation. ELISA was used to determine glucose stimulated insulin secretion in MIN6cells overexpressing NFATc3. RT-qPCR was used to determine gene expression levels in adenovirus mediated NFATc3overexpression in the cultured mouse islet cells. Immunofluorescence analysis was used to determine pancreatic beta cells proliferation and gene expression levels in NFATc3null mice fed with HFD.Results:NFATc3mRNA and protein levels were significantly reduced in the islets from HFD fed mice. Adenovirus mediated overexpression of NFATc3in MIN6cells increased Cyclin D1protein expression and MIN6cells proliferation. Overexpression of NFATc3also increased PPARy protein expression and promoted insulin secretion stimulated by high glucose. Adenovirus mediated NFATc3overexpression in the cultured mouse islet cells activated a number of genes including IRS-1,IRS-2,HNF1α and FoxO1. Reduced pancreatic islet number and size in HFD fed NFATc3null mice were found compared to wild type HFD fed mice. Immunocytochemistry showed that a number of important beta cells genes were down regulated, such as FoxA2and MafA, in the islets of HFD fed NFATc3null mice compared to that of wild type HFD fed mice.Conclusions:These results demonstrate that NFATc3plays an important role in maintaining pancreatic beta cells function and islet mass expansion under increased metabolic demand. Down regulation of NFATc3by HFD in pancreatic beta cells is one of the mechanisms by which HFD induces pancreatic beta cells dysfunction in the pathogenesis of Type2Diabetes.