胰岛素样生长因子-1对β-淀粉样前体蛋白裂解酶1的影响

Effects of insulin-like growth factor 1 on β-site amyloid precursor protein cleaving enzyme1

摘要:

目的：探讨胰岛素样生长因子-1（insulin-like growth factor-1，IGF-1）对人类神经母细胞瘤细胞SH-SY5Y中β-淀粉样前体蛋白裂解酶1（β-site amyloid precursor protein cleaving enzyme1，BACE1）的影响以及可能的细胞信号机制。方法：用不同剂量IGF-1（20、40 ng/ml和80 ng/ml）作用于人类神经母细胞瘤细胞SH-SY5Y 24 h，荧光定量PCR及Western blot检测BACE-1 mRNA及蛋白水平；Western blot检测淀粉样前体蛋白、C99、C83及磷脂酰肌醇－3激酶/丝氨酸苏氨酸蛋白激酶（phosphoinositide 3-kinase/serine threonine kinase，PI3-K/Akt）通路相关蛋白的水平；ＥLISA检测细胞培养液中β－淀粉样蛋白42（β-amyloid pep－tide，Ａβ４２）的水平，然后选择最佳剂量的IGF-1（80 ng/ml）作用于人类神经母细胞瘤细胞SH-SY5Y，在此之前30 min加入PI3-K抑制剂LY294002（25 μmol/L及50 μmol/L），重复上述检测。结果：IGF-1降低BACE-1、C99及Aβ42的水平（P=0.000），提高C83的表达（P=0.000），增加Akt的磷酸化（P=0.000），而LY294002具有抑制IGF-1的上述作用。结论：ＩGF-1降低BACE-1 mRNA及蛋白的水平，其机制可能涉及PI3-K/Akt信号通路。

Abstract:

Objective：To observe the effects of insulin-like growth factor-1（IGF-1） on β-site amyloid precursor protein cleaving en－zyme1（BACE1） and the possible cellular signaling mechanisms in SH-SY5Y human neuroblastoma cells. Methods：After SH-SY5Y human neuroblastoma cells being treated with 20，40 ng/ml and 80 ng/ml IGF-1 for 24 h，qPCR was used to analyze the levels of BACE-1 and Western blot was used to detect the protein levels of BACE1，C99，C83，amyloid precursor protein，mRNA and related protein levels of phosphoinositide 3-kinase/serine threonine kinase（PI3-K/Akt）. Cellular culture medium levels of β-amyloid pep－tide（Aβ42） were analyzed by ELISA. For inhibition studies，25 μmol/L and 50 μmol/L LY 294002，a specific PI3-K inhibitor，was administered 30 min prior to 80 ng/ml IGF-1 treatment. Then the above tests were repeated. Results：IGF-1 decreased levels of BACE-1，C99，and Aβ42（P=0.000） and increased expressions of C83 and pAkt（P=0.000）. LY294002 inhibited the above effects of IGF-1. Conclusion：IGF-1-induced reduction of BACE-1 may involve in PI3-K/Akt signaling pathway.