标题：Calcium influx activates adenylyl cyclase 8 for sustained insulin secretion in rat pancreatic beta cells
作者：Dou, Haiqiang; Wang, Changhe; Wu, Xi; Yao, Lijun; Zhang, Xiaoyu; Teng, Sasa; Xu, Huadong; Liu, Bin; Wu, Qihui; Zhang, Quanfeng; Hu 更多 作者机构：[Dou, Haiqiang; Wang, Changhe; Wu, Xi; Yao, Lijun; Zhang, Xiaoyu; Teng, Sasa; Xu, Huadong; Liu, Bin; Wu, Qihui; Zhang, Quanfeng; Hu, Meiqin; Wang, Yes 更多
通讯作者地址：[Chen, LY]Peking Univ, Inst Mol Med, 5 Yiheyuan Rd, Beijing 100871, Peoples R China.
关键词：Adenylyl cyclase 8; Ca2+; Pancreatic beta cell; Protein kinase A;; Vesicle pool
摘要：Insulin is a key metabolic regulator in health and diabetes. In pancreatic beta cells, insulin release is regulated by the major second messengers Ca2+ and cAMP: exocytosis is triggered by Ca2+ and mediated by the cAMP/protein kinase A (PKA) signalling pathway. However, the causal link between these two processes in primary beta cells remains undefined.; Time-resolved confocal imaging of fluorescence resonance energy transfer signals was performed to visualise PKA activity, and combined membrane capacitance recordings were used to monitor insulin secretion from patch-clamped rat beta cells.; Membrane depolarisation-induced Ca2+ influx caused an increase in cytosolic PKA activity via activating a Ca2+-sensitive adenylyl cyclase 8 (ADCY8) subpool. Glucose stimulation triggered coupled Ca2+ oscillations and PKA activation. ADCY8 knockdown significantly reduced the level of depolarisation-evoked PKA activation and impaired replenishment of the readily releasable vesicle pool. Pharmacological inhibition of PKA by two inhibitors reduced depolarisation-induced PKA activation to a similar extent and reduced the capacity for sustained vesicle exocytosis and insulin release.; Our findings suggest that depolarisation-induced Ca2+ influx plays dual roles in regulating exocytosis in rat pancreatic beta cells by triggering vesicle fusion and replenishing the vesicle pool to support sustained insulin release. Therefore, Ca2+ influx may be important for glucose-stimulated insulin secretion.