Downregulation of Long Noncoding RNA Meg3 Affects Insulin Synthesis and Secretion in Mouse Pancreatic Beta Cells.

Increasing evidence indicates that long noncoding RNAs (lncRNAs) are involved in diverse biological process. Mouse maternal expressed gene 3 (Meg3) is an imprinted gene and essential for development. Here, we explored the relationship between Meg3 and the function of mouse beta cells in vitro and in vivo. Real-time PCR analyses revealed that Meg3 was more abundantly expressed in Balb/c mouse islets than exocrine glands. Moreover, the expression of Meg3 in islets was decreased in T1DM (NOD female mice) and T2DM (db/db mice) models. Meg3 expression was modulated dynamically by glucose in Min6 cells and isolated mouse islets. The function role of Meg3 was investigated in Min6 cells and normal mouse by knockdown of Meg3 using small interfering RNA. After suppression of Meg3 expression in vitro, insulin synthesis and secretion were impaired and the rate of beta cells apoptosis was increased. Moreover, knockdown of Meg3 in vivo led to the impaired glucose tolerance and decreased insulin secretion, consisted with the reduction of insulin positive cells areas by immunochemistry assays. Notably, islets from Meg3 interference groups showed significant decrease of Pdx-1 and MafA expression in mRNA and protein levels. These results indicate that Meg3 may function as a new regulator of maintaining beta cells identity via affecting insulin production and cell apoptosis. J. Cell. Physiol. 231: 852-862, 2016.