姜黄素通过诱导热休克蛋白70保护多巴胺能细胞

Curcumin protects dopaminergic cells by inducing heat shock protein 70

目的探讨姜黄素通过诱导热休克蛋白70（Hsp70）高表达。抑制α-突触核蛋白的异常表达和聚集。促进蛋白酶体系统降解异常α-突触核蛋白对多巴胺能细胞的保护作用。方法选用大鼠嗜铬细胞瘤细胞株（PC12细胞），鱼藤酮诱导其损伤建立帕金森病细胞模型，利用姜黄素进行干预；采用MTT法检测细胞活力，荧光酶标仪检测蛋白酶体水解酶活性，Western blot检测Hsp70和α-突触核蛋白的表达，免疫荧光法检测细胞内Hsp70的表达和α-突触核蛋白的聚集。结果鱼藤酮组PC12细胞活力及蛋白酶体水解酶活性明显降低，Hsp70的表达轻度增加，α-突触核蛋白表达和聚集明显增加，与对照组比较差异有统计学意义f氏O．05）。经不同浓度姜黄素预处理4h后与0．1μmol／L鱼藤酮共同孵育PC12细胞24h，与鱼藤酮组比较，0．5μmol／L和1．0μmol／L姜黄素使细胞活力以及蛋白酶体水解酶活性明显升高，Hsp70表达明显升高，d．突触核蛋白的表达和聚集明显减少。差异有统计学意义（P〈0．05）；5．0μmol／L和10μmol／L姜黄素对鱼藤酮的拮抗作用明显减弱，细胞活力与鱼藤酮组比较差异均无统计学意义（P〉0．05），胰蛋白酶、多肽-谷氨酰-多肽水解酶活性与鱼藤酮组比较差异均无统计学意义（P〉0．05）；10μmol／L姜黄素组糜蛋白酶样水解酶活性进一步降低，与鱼藤酮组比较差异有统计学意义（P〈0．05）。结论低浓度姜黄素能够通过诱导PC12细胞表达Hsp70．诱导蛋白酶体水解酶活性表达．进而抑制α-突触核蛋白的表达和聚集。从而拮抗鱼藤酮诱导的PC12细胞的损伤。

Objective To explore the protective effects of curcumin on dopaminergic cells by inducing the expression of heat shock protein 70 （Hsp70）, inhibiting anormal expression and aggregation of a-synuclein and promoting proteasome system to degrade abnormal α-synuclein. Methods The cellular model of Parkinson＇s disease was induced by rotenone in the rat pheochromocytoma strain （PC 12 cells） and curcumin was also employed to intervene the cell expression. Cell viability was assessed by MTT assay and the activity of the 3 hydrolases in proteasome was measured by the method of fluorescent enzyme immunoassay. Western blotting was employed to detect the expressions of Hsp70 and α-synuclein and immunofluorescence was used to observe the expression of lisp70 and the aggregation of α-synuclein. Results The cell viability and the activity of proteasome in the rotenone group were decreased dramatically; the expression of Hsp70 was slightly increased while the expression and aggregation of α-synuclein was increased significantly as compared with those in other groups （P〈0.05）. Pretreatment with 0.5 μmol/L and 1.0 μmol/L curcumin resulted in significantly increased cell viability and activity ofproteasome in PC12 cells after co-incubation with 0.1 μmol/L rotenone for 24 h compared with the rotenone group; the expression of lisp70 was increased significantly and significantly decreased expression and aggregation of α-synuclein was found （P〈0.05）. The protective effects of 5.0 μmol/L and10 μmol/L curcumin against the rotenone-induced injury in PC12 cells decreased apparently; when the curcumin reached 10 μmol/L, the activity of chymotrypsin in proteasome statistically lower than that in the rotenone group; the activity of the other 2 enzymes in proteasome were not significantly different from that in the rotenone group （P〉0.05）. Conclusion Low concentration of curcumin can induce higher expression of lisp70 and higher activity of proteasome to inhibit the anormal expression and aggregation of a-synuclein in PC12 cells, thus it can alleviate the rotenone-induced injury in PC12 cells.