灵芝蛋白多糖对胰淀素聚集-内质网应激所致胰岛β细胞凋亡的干预作用研究

Islet function failure caused by increased beta-cell apoptosis is crucial for type 2 diabetes. The fibrosis of hIAPP caused by the change of protein structure from α helical to β sheet under pathological circumstance can induce the deposition of amyloid, and therefore evoke endoplasmic reticulum stress, which is one of the main causes of β cell apoptosis. Chemical drug which can interfere in beta-cell apoptosis affectively is lack in our clinic, while TCM has advantage in this aspect. Previous research have shown that the Chinese herb Ganoderma lucidum could increase the islet function and decrease the blood glucose in diabetic subjects. A proteoglycan from Ganoderma lucidum effectively decreased the blood glucose of diabetic rats as well as increased their β cell function. In vitro study also showed the proteoglycan could decrease the abnormal accumulation of human IAPP. Our project is planning to observe the influence of the proteoglycan from Ganoderma lucidum on beta-cell apoptosis, and explore its function on human IAPP accumulation, amyloid deposition, activation of endoplasmic reticulum transmembrane protein and CHOP and JNK pathway. We will deeply explore the mechanism of inhibition function of effective component of Chinese herb on beta-cell apoptosis in vitro and in vivo. We try to provide the theoretical basis on clinical application of Chinese herb on the improvement of islet function as well as the treatment of diabetes by this project.

胰岛β细胞凋亡增多引起的胰岛功能衰竭是2型糖尿病发生发展的中心环节。人胰淀素（hIAPP）多肽纤维化及异常聚集，形成淀粉样蛋白沉积，继而诱发内质网应激是胰岛β细胞凋亡的主要因素之一。目前临床缺少有效干预胰岛β细胞凋亡的化学药物，而中医药在这方面确有优势。课题组前期研究也发现灵芝能有效改善患者的胰岛功能，其有效成分灵芝蛋白多糖能有效改善糖尿病大鼠的血糖及胰岛功能，亦能有效减少hIAPP的异常聚集。本课题拟观察灵芝蛋白多糖对胰岛β细胞凋亡的影响，并研究其对hIAPP聚集、淀粉样蛋白沉积、内质网跨膜蛋白激活导致的内质网应激、以及同源蛋白(CHOP)和C-Jun氨基末端激酶(JNK)凋亡通路的作用。本课题从动物、细胞及分子水平深入探讨灵芝蛋白多糖通过干预胰淀素聚集-内质网应激进而抑制胰岛β细胞凋亡的机理，为中药改善胰岛功能的临床应用提供实验基础。

胰岛β细胞凋亡是2型糖尿病发生发展的中心环节。人胰淀素（hIAPP）多肽纤维化及异常聚集，形成淀粉样蛋白沉积，继而诱发内质网应激是胰岛β细胞凋亡的主要因素之一。课题组前期研究也发现灵芝能有效改善患者的胰岛功能，其有效成分灵芝蛋白多糖能有效改善糖尿病大鼠的血糖及胰岛功能。本课题拟观察灵芝蛋白多糖对胰岛β细胞凋亡的影响，并研究其对hIAPP聚集、淀粉样蛋白沉积、内质网跨膜蛋白激活导致的内质网应激、以及同源蛋白(CHOP)和C-Jun氨基末端激酶(JNK)凋亡通路的作用。主要从动物、细胞及分子水平三方面探讨灵芝蛋白多糖通过干预胰淀素聚集-内质网应激进而抑制胰岛β细胞凋亡的机理。. 实验结果表明：1. FYGL在体外可呈浓度依赖性抑制hIAPP纤维形成及hIAPP二级结构由α-螺旋向β-折叠态转变；同时在转基因小鼠模型hIAPP实验结果也看到FYGL可减少胰岛淀粉样蛋白沉积。2. FYGL及其含药血清有促进min6细胞增殖作用，同时FYGL可呈剂量依赖性抑制hIAPP诱导INS1胰岛细胞凋亡；hIAPP转基因小鼠实验结果也看到FYGL可改善小鼠胰岛β细胞功能及血糖。3. 细胞及动物实验结果表明FYGL可抑制内质网应激CHOP/JNK信号通路相关蛋白的表达。. 总之：实验结果与之前设想一致，FYGL可通过抑制hIAPP多肽异常聚集及胰岛β细胞内质网应激进而减少β细胞凋亡起到控制血糖作用。FYGL可能作为一种具有保护胰岛β细胞作用的潜在降糖药物。