CCKAR在胰岛B细胞中的偏向性信号转导及针对CCKAR的功能选择性APTAMER的筛选

The Cholecystokinin A receptor (CCKAR) is a widely expressed G protein-coupled receptor which has been identified in gallbladder, pancreas and neuronal system. CCKAR regulates smooth muscle contraction of gall bladder, pancreatic enzyme secretion and satiety in nervous system. Recently, research revealed that CCK promoted insulin secretion in diabetes patients and the CCKAR deficient OLETF male rat developed type2 diabetes. Therefore CCKAR received a great deal of attention for its potential as a diabetes therapeutic target, while we know very little about CCKAR mediated cellular signaling in pancreatic beta cells and how CCKAR signaling regulates pancreatic beta cell function. In this proposal, we set out to use multiple approaches, including cell biology, electrophysiology and chemical biology methods, the recent developed receptor-effector fusion protein technique, together with CCKAR deficient OLETF rat, beta-arrestin knock out mice and STZ induced diabetes mice model to study the CCKAR signaling in pancreatic beta cells and their important role in regulation of pancreatic beta cell functions. Further, we will develop a new functional GPCR apatmer selection method, to acquire aptamers specifically targeting to CCKAR selective functions. We are going to evaluate therapeutic potential for these acquired aptamers through testing them in cell signaling, pancreatic beta cell functions and animal models. Finally, we are going to investigate the cell signaling and pancreatic beta cell functions of CCKAR polymorphism, which will lay the foundation for future personal therapy development.

胃肠激素受体CCKAR是缩胆囊素的受体，调控胆囊收缩和胰酶分泌等生理活动。近年来，CCKAR成为治疗代谢综合征尤其是糖尿病的重要药物靶蛋白。但是对CCKAR在胰腺B细胞中信号通路及生理功能由于缺乏有效研究手段知之甚少，阻碍了相关药物研发。本项目将联合细胞生物学,电生理和化学生物学手段，应用新发展的受体-效应器融合蛋白技术，及基因敲除和化学诱导等动物模型,深入研究CCKAR对胰腺B细胞功能调控及其信号途径。本项目的研究不仅可阐明CCKAR的下游效应器偏向性信号途径如何调节胰岛素分泌，葡萄糖敏感性和胰腺B细胞凋亡;还通过新建立针对 GPCR超家族的功能性Aptamer筛选方法，获得CCKAR的偏向性Aptamer,并评估其做为代谢综合征治疗药物的潜力。此外，作为本项目的一部分，我们还研究CCKAR基因多态性对胰岛信号途径的影响,为发展基于CCKAR多态性的个性化疗法奠定基础。

胃肠激素受体CCKAR（也称为CCK1R）是缩胆囊素的受体，调控胆囊收缩和胰酶分泌等生理活动。近年来，CCKAR已成为治疗代谢综合征尤其是糖尿病的重要药物靶蛋白。但是对CCKAR介导的信号通路及生理功能由于缺乏有效研究手段知之甚少，阻碍了相关药物研发。本课题依据项目申请书，研究了CCKAR在胰岛B细胞中的功能，发现选择性激活CCKAR在小鼠糖尿病模型中对糖代谢和胰岛稳态有显著的改善作用。激活CCKAR可以促进胰岛素分泌，抑制胰岛细胞的不正常凋亡。我们的细胞生物学研究发现，CCKAR的下游Gq-PLC信号途径对胰岛的功能是有害的，在没有高糖的刺激条件下，也能促进胰岛素的分泌；而CCKAR的下游Gs-cAMP-PKA信号途径对胰岛素功能是有益的，提高胰岛B细胞对葡萄糖的敏感性。除了G蛋白以外，CCKAR还可通过下游β-arrestin-1信号途径，激活ERK-RSK-BAD，从而对胰岛B细胞有保护的作用。进一步，我们还阐释了CCKAR通过磷酸化编码指导β-arrestin-1功能的机制，并开发获得了只激活CCKAR-β-arrestin-1信号途径的Aptamer。在四年的研究周期中，我们的相关实验结果在British Journal of Pharmacology, Nature Communications 等SCI收录杂志发表了14篇标注本课题基金号的论文，课题负责人作为全部这些文章的通讯作者。我们的研究不仅阐明了CCKAR对胰岛稳态的调控作用及机制，也为进一步开发靶向CCKAR来开发治疗糖尿病的药物奠定了基础。

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