香菇菌丝体抗氧化多糖通过p38MAPK和JNK通路对糖毒性所致胰岛β细胞损伤保护作用研究

Edible-medicinal fungi is an important component of natural medicine resources in our country. They have already be widely used in food and drug field. Antioxidant substances isolated from natural products with the protection of pancreatic β cell normal function is a hot spot in current research and has been one of the best ways to prevent diabetes and promote the function of pancreatic β cell. The new Lentinus edodes mycelium antioxidant polysaccharide (LMP) were prepared. Preliminary results showed that LMP can reduce the level of reactive oxygen species of pancreatic β cell by inhibiting the activation of p38MAPK signal pathway induced by H2O2, which cause pancreatic β cell apoptosis. n order to investigate whether LMP can protect pancreatic β cell, the cell survival environment of pancreatic β cell under the condition of diabetes pathological was simulated by applying high glucose to induce pancreatic β cell damage. The activity of polysaccharide against glucotoxicity by inhibiting activation of p38 MAPK and JNK signal pathway will be determined respectively. At the same time, the insulin gene promoter luciferase reporter gene plasmid will be built. The influence of the polysaccharide on insulin gene expression and activity of promoter will be analysis and its effect on promoting insulin secretion will be investigated by using dual luciferase reporter gene analysis technology and ChIP technology. Finally, the protective effect of the polysaccharide on pancreatic β cell will be evaluated at animal level. Then the exact mechanism of LMP protect pancreatic β cell will be systematically illustrated at the molecular, cellular, and diabetes animal. The overall goal of the study is to provide a scientific basis for the fungus resource exploitation and function exploring of fungi polysaccharide.

食药用真菌是我国天然药物资源的重要组成部分，已被广泛应用于食品和药品领域。具有保护胰岛β细胞功能的天然抗氧化物质筛选已成为糖尿病预防与治疗的有效途径之一。实验室前期制备了新型的香菇菌丝体抗氧化多糖（LMP），实验结果显示LMP能够降低胰岛β细胞活性氧水平，抑制H2O2诱导p38MAPK通路激活而造成的胰岛β细胞凋亡。为研究LMP保护胰岛β细胞功能，模拟病理条件下细胞生存环境，分别从p38MAPK和JNK通路角度，研究LMP抑制糖毒性诱导胰岛β细胞凋亡和信号转导机制；利用荧光素酶报告基因分析技术和染色质免疫沉淀技术（ChIP）分析多糖对糖毒性下胰岛素基因表达和启动子活性影响，考察其促进胰岛素基因表达和胰岛素分泌作用；最后在动物水平上评价其保护胰岛β细胞功能。从分子、细胞、整体动物水平上系统阐明LMP保护胰岛β细胞的确切机制，以期为真菌资源的开发和真菌多糖功能研究提供理论和实验依据。

食药用真菌是我国天然药物资源的重要组成部分，具有保护胰岛β细胞功能的天然抗氧化物质筛选已成为糖尿病防治的有效途径之一。本项目施加高糖，模拟病理条件下细胞生存环境，研究实验室前期制备的香菇菌丝体抗氧化多糖保护胰岛β细胞功能及作用机制。结果证明香菇菌丝体抗氧化多糖可改善糖毒性诱导的胰岛β细胞（INS1和Min6）凋亡和功能减退，具有较好的调节胰岛素基因表达、启动子活性的功能，通过抑制糖毒性诱导的p38 MAPK、JNK信号通路激活、促进Nrf2及PDX-1的核转位来保护胰岛β细胞，并对2型糖尿病大鼠有较好的防治作用。本项目从分子、细胞、整体动物水平上系统阐明香菇菌丝体抗氧化多糖保护胰岛β细胞的确切机制，为真菌资源的开发和真菌多糖功能研究提供较好的实验依据。