CAPS1蛋白S259位点磷酸化介导胰岛神经预调控在β细胞头期分泌中的机制研究

胰岛功能障碍是糖尿病核心病理机制之一，其中胰岛头期分泌功能受损与餐后血糖稳态失衡密切相关。副交感神经通过乙酰胆碱（ACh）对β细胞头期分泌具有重要调控，但机制尚不明确。新近发现CAPS1蛋白作为钙依赖分泌激活因子，参与囊泡分泌及转运，其基因敲除小鼠出现胰岛素分泌障碍及糖耐量异常。我们前期发现ACh可诱导胰岛β细胞CAPS1 S259位点显著磷酸化修饰，生信分析提示KSR2为其上游调控激酶，且抑制KSR2后ACh刺激下β细胞分泌能力下降。因此我们推测ACh通过KSR2激酶介导β细胞CAPS1磷酸化后激活蛋白功能，调控胰岛素分泌及囊泡转运，增强β细胞对葡萄糖刺激敏感性及反应性，发挥胰岛头期分泌调控作用。本研究通过构建CAPS1点突变β细胞系及小鼠模型并结合人胰岛实验，利用钙成像、胰岛灌流及葡萄糖钳夹技术，探索副交感神经对β细胞头期分泌预调控作用机制，为改善糖尿病胰岛功能障碍探索新的治疗靶点。

Pancreatic islet dysfunction is one of the critical pathological mechanisms of diabetes. The impaired cephalic phase of beta cell secretion is closely related to the postprandial blood glucose homeostasis imbalance. The parasympathetic innervation in islet plays an important role in regulating beta cell secretion through acetylcholine (ACh), but the mechanism is remained unclear. Recently, it was reported that calcium-dependent secretion activator CAPS1 participated in the process of vesicle secretion and transport, and the impaired glucose tolerance and decreased insulin secretion rate were found in the CAPS1 knockout mouse. Our previous study also had found that ACh could induce CAPS1 S259 phosphorylation in pancreatic β-cells. Bioinformatics analysis suggested that KSR2 was the upstream regulatory kinase of CAPS1, and the secretion ability of beta cell was decreased after KSR2 inhibition under ACh stimulation. Therefore, we speculated that CAPS1 was activated after phosphorylation under the treatment of neurotransmitters ACh, which regulated insulin secretion and vesicle transport to enhance the sensitivity and responsiveness of beta cell under glucose stimulation, and played critical roles in the regulation of cephalic phase of hormones secretion. In this study, the point mutation β cell line and mouse model of CAPS1 gene were constructed combined with human islet, using calcium imaging, islet perfusion and glucose clamp to explore the pre-regulation of parasympathetic nerve on cephalic phase of insulin secretion, and explored the new therapeutic targets for improving islet dysfunction of diabetes mellitus.