Vascular endothelial growth factor B regulates insulin secretion in cells of type 2 diabetes mellitus mice via PLC and the IP3R-evoked Ca²⁺/CaMK2 signaling pathway

Vascular endothelial growth factor B (VEGFB) plays a crucial role in glucolipid metabolism and is highly associated with type 2 diabetes mellitus (T2DM). The role of VEGFB in the insulin secretion of beta cells remains unverified. Thus, the present study aimed to discuss the effect of VEGFB on regulating insulin secretion in T2DM development, and its underlying mechanism. A high-fat diet and streptozocin (STZ) were used for inducing T2DM in mice model, and VEGFB gene in islet cells of T2DM mice was knocked out by CRISPR Cas9 and overexpressed by adeno-Associated Virus (AAV) injection. The effect of VEGFB and its underlying mechanism was assessed by light microscopy, electron microscopy and fluorescence confocal microscopy, enzyme-linked immuno-sorbent assay, mass spectrometer and western blot analysis. The decrement of insulin secretion in islet beta cell of T2DM mice were aggravated and blood glucose remained at a high level after VEGFB knockout (KO). However, glucose tolerance and insulin sensitivity of T2DM mice were improved after the AAV-VEGFB186 injection. VEGFB KO or overexpression can inhibit or activate PLC gamma/IP3R in a VEGFR1-dependent manner. Then, the change of PLC gamma/IP3R caused by VEGFB/ VEGFR1 will alter the expression of key factors on the Ca2+/CaMK2 signaling pathway such as PPP3CA. Moreover, VEGFB can cause altered insulin secretion by changing the calcium concentration in beta cells of T2DM mice. These findings indicated that VEGFB activated the Ca2+/CaMK2 pathway via VEGFR1-PLC gamma and IP3R pathway to regulate insulin secretion, which provides new insight into the regulatory mechanism of abnormal insulin secretion in T2DM.