Increased glycogen synthase kinase 3β activity involves in the decreased expression of Bmal1 induced by amyloid-beta protein 31-35 in HT22 cells / 中华神经科杂志

ABSTRACT

Objective To investigate the effect of glycogen synthase kinase 3β (GSK3β) on the decreased expression of Bmal1 induced by amyloid-beta protein 31-35 (Aβ31-35) in HT22 cells.Methods HT22 mouse hippocampal cells were divided into control group,Aβ31-35 group and LiCl+Aβ 31-35 group by random number table method in the present study.Cells were synchronized to G0/G1 phase by 1％ serum starvation for 1 hour (circadian time 0 (CT0)).Cell viability was detected by the cell counting kit-8 assay.The mRNA expression of clock gene Bmal1 was examined by real-time PCR at different CT times.The expression of GSK3β and BMAL1 protein was detected by Western blotting.Results Compared with the control group,Aβ31-35 induced the decreased expression of Bmal1 mRNA;The expression of both Bmal1 mRNA and BMAL1 protein was decreased significantly at CT20 (Bmal1 mRNA0.38±0.06 vs 0.83±0.08,t=4.549,P=0.001;BMAL1 protein0.67±0.04 vs 1.00±0.04,t=5.943,P＜0.001).In the Aβ31-35group,GSK3β activity was increased and the ratio of phosphorylated GSK3βS9 to GSK3β was decreased compared to the control group (0.66±0.08 vs 1.02±0.14,t=2.217,P=0.025).Aβ31-35 decreased the viability of HT22 cells (71.85％±6.20％ in the Aβ31-35 group vs 98.14％±2.68％ in the control group,t=3.891,P=0.006),and the GSK3β inhibitor LiC1 pretreatment effectively reversed the decline of the viability induced by Aβ31-35 (90.74％±5.74％ in the LiCl+Aβ31-35 group vs 71.85％±6.20％ in the Aβ31-35 group,t=3.412,P=0.010).LiCl (in the LiCl+Aβ31-35 group) increased the expression of Bmal1 mRNA and BMAL1 protein significantly at CT20 compared with the Aβ31-35 group (Bmal1 mRNA0.72±0.05 vs 0.38±0.06,t=4.378,P=0.001;BMAL1 protein0.90±0.04 vs 0.67±0.04,t=4.052,P=0.002).Conclusion Increased GSK3β activity involved in the decreased expression of Bmal 1 induced by Aβ31-35 in HT22 cells.