Endocrine Connections (Jan 2022)
Angiotensin(1–7) activates MAS-1 and upregulates CFTR to promote insulin secretion in pancreatic β-cells: the association with type 2 diabetes
Abstract
Objective: The beneficial effect of angiotensin(1–7) (Ang(1–7)), via the ac tivation of its receptor, MAS-1, has been noted in diabetes treatment; however, how Ang(1–7) or MAS-1 affects insulin secretion remains elusive and whether the endoge nous level of Ang(1–7) or MAS-1 is altered in diabetic individuals remains unexplored. We recently identified an important role of cystic fibrosis transmembrane conductance regu lator (CFTR), a cAMP-activated Cl− channel, in the regulation of insulin secretion. Here, we tested the possible involvement of CFTR in mediating Ang(1–7)’s effect on insulin se cretion and measured the level of Ang(1–7), MAS-1 as well as CFTR in the blood of in dividuals with or without type 2 diabetes. Methods: Ang(1–7)/MAS-1/CFTR pathway was determined by specific inhibito rs, gene manipulation, Western blotting as well as insulin ELISA in a pancreatic β-cell line, RINm5F. Human blood samples were collected from 333 individuals with (n = 197) and without (n = 136) type 2 diabetes. Ang(1–7), MAS-1 and CFTR levels in the human blood were determined by ELISA. Results: In RINm5F cells, Ang(1–7) induced intracellular cAMP increase, cAMP-response element binding protein (CREB) activation, enhanced CFTR expres sion and potentiated glucose-stimulated insulin secretion, which were abolished by a selective CFTR inhibitor, RNAi-knockdown of CFTR, or inhibition of MAS-1. In human subjects, the blood levels of MAS-1 and CFTR, but not Ang(1–7), were significantly higher in i ndividuals with type 2 diabetes as compared to those in non-diabetic healthy subjects. In addition, blood levels of MAS-1 and CFTR were in significant positive correlation in ty pe-2 diabetic but not non-diabetic subjects. Conclusion: These results suggested that MAS-1 and CFTR as key players in mediating Ang(1–7)-promoted insulin secretion in pancreatic β-cells; MAS-1 and CFTR are positively correlated and both upregulated in type 2 diabetes.
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