Involvement of phospholipase D in glucose stimulate insulin signaling pathway in pancreatic β cells

Abstract

Glucose has been known to induce insulin secretion in pancreatic β cells. In this study, we investigated the phospholipase D (PLD)-related signaling pathway for insulin secretion caused by high glucose in MIN6N8 cells, a mouse pancreatic β-cell line. PLD was activated maximally at 10min treatment by high glucose (33.3mM) in the cells. We found that expression of PLD1 was also increased by treatment of high glucose to the cells. Overexpression of PLD1 resulted in increased insulin secretion, while high glucose-induced insulin secretion was blocked by transfection of PLD1siRNA. These results suggest that high glucose increased insulin secretion through PLD1-related pathway. Next, we monitored the translocation of PKC and Arf6 in response to high glucose , treatment of high glucose induces translocation of both of Arf6 and PKC. After translocation of these molecules, they could bind to PLD1, respectively. To investigate the involvement of PKC-Arf6-PLD1 pathway in glucose-induced insulin secretion, we used PKC inhibitor (RO320432) and Arf inhibitor (BFA). Pretreament with RO320432 and BFA respectively, inhibited PLD activity resulted in decreased insulin secretion. Taken together, these results suggest that high glucose-induced insulin secretion might be regulated by PKC-Arf6 dependent manner with involvement of PLD1 in MIN6N8 cells.