GLP-1受体激动剂调控FGF21自分泌改善胰岛β细胞功能和存活的作用及机制

It has been confirmed that both GLP-1 and FGF21 improve pancreatic β cell function and survival. However, the mutual regulation between them has not been validated. Our previous studies showed that GLP-1 receptor agonist (GLP-1RA) improved pancreatic islet function in db/db mice and inhibited palmitate-induced β cell apoptosis. Our preliminary studies showed that the fluorescence intensity of islet FGF21 was enhanced in db/db mice with GLP-1RA administration and the production of FGF21 was increased in GLP-1RA treated mouse β cell line. The aim of this project is to investigate the effect of GLP-1RA on the expression and secretion of FGF21 and the function and survival of β cells in db/db mice and palmitate-induced primary islets and β cell lines. The role of FGF21 in GLP-1RA improving β cell function and survival will be examined using FGF21 neutralizing antibodies or gene knockdown techniques. The differential expression of GLP-1 receptor, FGF21 receptor and their downstream signaling pathways will be characterized. And the role of regulated molecules mediated by GLP-1RA in regulating FGF21 production and the β cell function and survival will be identified by antagonists or gene knockdown techniques. The project will elucidate the new mechanism of GLP-1 in protecting β cells and provide a scientific basis for improving the development of diabetes treatment strategies.

业已证实，GLP-1和FGF21均可改善胰岛β细胞功能和存活，但两者之间是否存在相互调控尚未见报道。课题组前期研究显示，GLP-1受体激动剂（GLP-1RA）可改善db/db小鼠胰岛功能，抑制棕榈酸诱导的β细胞凋亡。预实验结果显示，GLP-1RA升高db/db小鼠胰岛FGF21荧光强度，促进小鼠β细胞系FGF21产生。本项目拟在db/db小鼠及棕榈酸诱导的原代胰岛和β细胞系中探讨GLP-1RA对FGF21表达和分泌及对β细胞功能和存活的影响，利用FGF21中和抗体或敲减技术验证FGF21是否参与GLP-1RA改善β细胞功能和存活。检测GLP-1受体、FGF21受体及下游信号通路的变化，通过添加拮抗剂或联合基因敲减技术验证特异信号分子在GLP-1RA调控FGF21产生进而改善β细胞功能和存活中的介导作用。本项目的开展有助于阐明GLP-1保护β细胞的新机制，为糖尿病治疗新策略研发提供科学依据。

业已证实，胰高糖素样肽-1（GLP-1）和成纤维细胞生长因子21（FGF21）均可改善胰岛β细胞功能和存活，但两者之间是否存在相互调控尚未见报道。本课题显示GLP-1受体激动剂艾塞那肽可增加2型糖尿病患者和2型糖尿病小鼠（db/db小鼠）血浆FGF21水平。体外研究显示，GLP-1受体激动剂利拉鲁肽可剂量依赖性增加小鼠原代胰岛细胞和β细胞系（min6细胞）FGF21水平。以上结果提示，GLP-1受体激动剂可直接调控β细胞产生FGF21。为进一步明确FGF21是否介导GLP-1受体激动剂对β细胞功能调控作用。本研究利用艾塞那肽联合或不联合FGF21中和抗体干预db/db小鼠2周，结果显示，艾塞那肽可显著降低db/db小鼠空腹血糖，改善db/db小鼠糖耐量。与单纯艾塞那肽干预组相比，艾塞那肽联合FGF21中和抗体组，小鼠空腹血糖升高，糖负荷后血糖同样升高，提示FGF21在GLP-1受体激动剂改善血糖方面发挥重要作用。离体实验中，利用糖基化终末产物（AGEs）在min6细胞系中构建离体β细胞损伤模型，利用利拉鲁肽干预细胞24 h，结果显示，AGEs可显著上调min6细胞凋亡水平，而利拉鲁肽可逆转AGEs所致的损伤效应，同时上调细胞FGF21水平。在此基础上添加FGF21中和抗体后，损伤效应进一步加重。分离β细胞FGF21特异性敲除小鼠和同窝Cre对照小鼠原代胰岛，高糖（2 g/L）孵育，利用利拉鲁肽干预细胞24 h，检测小鼠Ins1、Ins2等基因表达。结果显示，利拉鲁肽干预后，Cre小鼠Ins1、Ins2等基因表达水平显著升高；而β细胞FGF21特异性敲除小鼠Ins1、Ins2等基因表达水平不升高，以上结果提示FGF21在GLP-1受体激动剂改善β细胞功能、抑制β细胞损伤中发挥重要作用。本项目的开展有助于阐明GLP-1保护β细胞的新机制，为糖尿病治疗新策略研发提供科学依据。本项目发表SCI论文4篇，研究成果在2018年度中华医学会糖尿病学分会年会上进行口头发言，并获得优秀病例奖。协助洪天配教授培养研究生2名。