The Regulation Of The Expression Of Cav 1.2?Cav 1.3 And Cav2.3 In Pancreatic ? Cells By Paracrine Factors

Diabetes is a metabolic disorder that is characterized by a relative or absolute deficiency of insulin secretion and a marked increase in blood glucose concentration,and is widely concerned in the world due to its high incidence. Islets play a central role in regulating blood glucose homeostasis. The functional defect of islets is an important factor in the development of diabetes. Islet contains at least five types of endocrine cells: ? cells secrete insulin, ? cells secrete glucagon, ? cells secrete somatostatin, ? cells secrete hunger hormones and pp cells secrete pancreatic peptides.Most islet ? cells in human islets are closely adjacent to a cells or ? cells.Different types of cells interact with each other to form islet microcirculation by paracrine, regulating the relative proportions and levels of insulin and glucagon secretion. So that the body can maintain blood glucose balance in different physiological environment to. The insulin and GABA secreted by ? cells inhibits the glucagon secretion by a cells, whereas the glucagon stimulates ? cells to secrete insulin. Meanwhile, somatostatin secreted by ? cells inhibits the secretion of insulin and glucagon in a paracrine pattern.Paracrine disorders lead to the collapse of the islet microcirculation circuit destruction, which is an important reason for the development of diabetes. For example,the loss of an important paracrine factor UCN3 in pancreatic islet cells leads to somatostatin-mediated dysfunction of the islet ? cells and the ?-cell negative feedback loop, leading to glucose-induced abnormalities in insulin release, further triggering diabetes occur.Pancreatic ? cells cell secrete somatostatin,which can inhibit the secretion of insulin and glucagon, lower blood levels of two hormones, is an important paracrine factor. In recent years, the important role of ? cells in maintaining the balance of blood glucose metabolism in the body has been paid more and more attention. Studies have found that somatostatin secretion regulate by intracellular Ca2+ and cAMP.Glucose-induced somatostatin secretion is mainly dependent on calcium-induced calcium release (CICR), and R-type calcium channels and L-type calcium channels play an important role in it. R-type calcium channel Cav2.3 knockout mice (Cav2.3 -/-)islet, glucose-induced somatostatin secretion is 75% less than wild type. UCN3 can enhance glucose-stimulated ? cell somatostatin secretion. Application of L-type calcium channel blocker isradipine can eliminate the enhancement of UCN3. Our latest study shows that sustained UCN3 stimulation can reduce the expression level of CRL4B-PRC2 complex and reduce the inhibitory effect of CRL4B-PRC2 complex on Cav1.2 expression in ? cells, and increase the expression of Cavl.2. Then promote thesecretion of somatostatin. In addition to UCN3, insulin and GABA are also important paracrine factors secreted by ? cells. Therefore, this article mainly discusses whether paracrine factors insulin and GABA secreted by ? cells can regulate the expression of Cav1.2, Cav1.3 and Cav2.3 in ? cells, and make a preliminary study on the mechanism of insulin signaling in Cav1.2 regulation.Research purposesTo investigate the potential regulation of the expression of Cav1.2, Cav1.3 and Cav2.3 in ? cells by different paracrine factors.Research methods1. RT-PCR and q-RT-PCR were performed to detect the mRNA levels of Cav1 .2,Cav1.3 and Cav2.3 in the ? cells stimulated by insulin, GABA and UCN3.2. Western blot was performed to detect the expression levels of Cav1.2, Cav1.3 and Cav2.3 in the 8 cells stimulated by insulin, GABA and UCN3.3. Western blot was performed to detect the phosphorylation levels of ERK and AKT in the ? cells upon insulin stimulation.4. Detect the calcium currents in 8 cells by electrophysiological patch clamp.Results1. The results of RT-PCR and q-RT-PCR showed that the mRNA levels of Cav1.2 in ? cells were significantly increased by continuous insulin and UCN3 stimulation, and the mRNA levels of Cavl.3 and Cav2.3 were significantly increased by continuous GABA stimulation?2. The results of WESTERN BLOT showed that the expression of Cav1.2 was significantly increased by continuous insulin and UCN3 stimulation, and the expression of Cav1.3 and Cav2.3 was significantly increased under continuous GABA stimulation.3. Insulin stimulated the phosphorylation of ERK1/2 and AKT in ? cells.4. ERK blocker U0126 can significantly inhibit the expression of Cav1.2 and Cav2.3 stimulated by insulin in 8 cells, while AKT blocker MK-2206 has no obvious inhibitory effect.5. Calcium current of pancreatic 8 cell can be detected by patch clamp.Conclusion1. Sustained UCN3 and insulin stimulation significantly increased the expression of Cav1.2 in ? cells.2. Sustained GABA stimulation significantly increased the expression of Cav1.3 and Cav2.3 in ? cells.3. Insulin regulates the expression of Cav1.2 in ? cells may through the MAPK-ERK pathway.