胰岛素抑制突变亨廷顿蛋白的聚积和毒性

Insulin inhibition of the accumulation and toxicity of mutant huntingtin

目的:探讨胰岛素对细胞内突变亨廷顿蛋白(Huntingtin,htt)聚集物形成及其细胞毒性的影响。方法:利用脂质体转染法在培养的Hela细胞和HEK293细胞瞬时或稳定转染编码正常或突变htt的氨基末端片段的cDNA,检测不同浓度胰岛素刺激对细胞内突变htt聚集物形成以及细胞活力的影响。结果:在瞬时转染的Hela细胞和稳定转染的HEK293细胞中,含20个谷氨酰胺重复序列(20Q)的正常htt氨基末端片段弥散分布在胞浆内,而含150个谷氨酰胺重复序列(150Q)的突变htt氨基末端片段在多数细胞胞浆或核内形成聚集物。150Q的Hela和HEK293细胞经一定浓度的胰岛素刺激后聚集物的形成显著减少,细胞活力也明显提高。而胰岛素的刺激对20Q的细胞内正常htt的表达以及细胞活力无明显影响。结论:胰岛素能有效抑制细胞内突变htt聚集物的形成及其细胞毒性。

OBJECTIVE To explore the influence of insulin on accumulation and toxicity of mutant huntingtin （htt） in cells. METHODS By using Lipofactamine 2000,cultured Hela or HEK293 cells were transiently or stably transfected with cDNAs encoding normal or mutant huntingtin amino-terminal fragments,and the effects of different concentration insulin treatment on the accumulation of mutant huntingtin and cellular viability were detected. RESULTS In transiently transfected Hela cells and stably transfected HEK293 cells that expresed amino-terminal fragments of normal huntingtin containing 20 glutamine repeats （20Q） ,20Q was diffusely distributed in the cytoplasm, whereas, in most of cells that expressed mutant huntingtin containing 150 glutamine repeats （150Q） ,aggregates of the mutant htt were formed in the cytoplasm and nuclei. After stimulated by certain concentrated insulin, 150Q Hela and HEK293 cells showed reduced aggregates of mutant htt and increased cellular viability. Whereas insulin did not affect the expression of normal huntingtin and cellular viability. CONCLUSION Insulin can effectively inhibit the aggregates formation of mutang huntingtin and its cytotoxicity.