颅脑损伤后海马区notch信号分子及其相关miRNA的表达变化

目的 观察颅脑损伤后海马区notch1相关微小RNA(miRNA)、notch1及nestin的表达变化,探讨颅脑损伤后神经干细胞增殖机制.方法 采用自由落体法复制闭合性颅脑损伤小鼠模型,于伤后4 h、1 d和3 d处死动物.(1)实时聚合酶链反应(Real-time PCR)检测伤后4 h、1 d和3d伤侧海马区mir-326、mir-34a和notch1 mRNA的表达变化.(2)免疫荧光染色检测伤后3 d伤侧海马齿状回区notch1和nestin蛋白表达变化.结果 (1)颅脑损伤后4 h、1 d和3 d组海马区mir-326和mir-34a表达水平分别为假手术组的(0.36±0.16)、(0.16±0.04)、(0.36±0.17)倍和(0.48±0.15)、(0.50±0.04)、(0.25±0.14)倍,均低于假手术组(P＜0.01);(2)颅脑损伤后4 h、1 d和3 d组海马区notch1 mRNA表达水平分别为假手术组的(1.77±0.17)、(2.55±0.48)和(2.44±0.58)倍,均高于假手术组(P＜0.05);颅脑损伤后3 d组海马齿状回区notch1阳性细胞明显多于假手术组[(18.20±3.56)个比(0.40±0.55)个,P＜0.01].(3)颅脑损伤后3 d组海马齿状回区nestin阳性细胞数明显高于假手术组[(21.80±5.07)个比(0.80±0.45)个,P＜0.01].结论 在颅脑损伤后海马区神经干细胞增殖过程中,mir-326和mir-34a表达明显降低,其靶基因notch1 mRNA和蛋白表达明显升高,提示mir-326和mir-34a可靶向抑制notch信号分子,调控伤后神经干细胞增殖过程.

Abstract：

Objective To observe the expression of notch1-related miRNA, notch1 and nestin,and explore the regulatory mechanism of neural stem cells proliferation in hippocampus of mice after traumatic brain injury (TBI). Methods Mice were suffered closed head injury, and then sacrificed at 4th h,1st day and 3rd day post-injury. Real-time polymerase chain reaction (PCR) was used to detect the expression levels of mir-326, mir-34a and notch1 mRNA in mice hippocampus at 4th h, 1st day and 3rd day post TBI. Immunofluorescence was conducted to determine protein expression levels of notch1 and nestin in mice hippocampus at 3rd day post TBI. Results ( 1 ) Relative to sham group, the levels of mir-326 and mir-34a at 4th h, 1st day and 3rd day after TBI in the hippocampus were respectively (0. 36 ± 0. 16),(0. 16±0.04), (0.36±0. 17) and (0.48±0. 15), (0.50±0.04), (0.25 ±0. 14) fold (P＜0.01);(2) Relative to sham group, the levels of notch1 mRNA at 4th h, 1st day and 3rd day post TBI injury in the hippocampus were respectively (1.77 ±0. 17), (2.55 ±0.48) and (2.44±0.58) fold (P＜0.05).Notch1 + cells in the DG at 3rd day post TBI were significantly increased compared to sham group ( 18.20± 3.56 vs 0. 40 ±0. 55 ,P ＜0. 01 ); (3) Nestin + cells in the DG at 3rd day post TBI were increased apparently compared to sham group (21.80 ± 5. 07 vs 0.80 ± 0. 45, P ＜ 0. 01 ). Conclusion mir-326 and mir-34a may play a key role in trauma-induced neural stem cells proliferation in hippocampus in vivo by targeting notch1 signaling.

Expression changes of notch1 signaling and notch1 signaling-related miRNA in the hippocampus after traumatic brain injury

Objective To observe the expression of notch1-related miRNA, notch1 and nestin,and explore the regulatory mechanism of neural stem cells proliferation in hippocampus of mice after traumatic brain injury (TBI). Methods Mice were suffered closed head injury, and then sacrificed at 4th h,1st day and 3rd day post-injury. Real-time polymerase chain reaction (PCR) was used to detect the expression levels of mir-326, mir-34a and notch1 mRNA in mice hippocampus at 4th h, 1st day and 3rd day post TBI. Immunofluorescence was conducted to determine protein expression levels of notch1 and nestin in mice hippocampus at 3rd day post TBI. Results ( 1 ) Relative to sham group, the levels of mir-326 and mir-34a at 4th h, 1st day and 3rd day after TBI in the hippocampus were respectively (0. 36 ± 0. 16),(0. 16±0.04), (0.36±0. 17) and (0.48±0. 15), (0.50±0.04), (0.25 ±0. 14) fold (P＜0.01);(2) Relative to sham group, the levels of notch1 mRNA at 4th h, 1st day and 3rd day post TBI injury in the hippocampus were respectively (1.77 ±0. 17), (2.55 ±0.48) and (2.44±0.58) fold (P＜0.05).Notch1 + cells in the DG at 3rd day post TBI were significantly increased compared to sham group ( 18.20± 3.56 vs 0. 40 ±0. 55 ,P ＜0. 01 ); (3) Nestin + cells in the DG at 3rd day post TBI were increased apparently compared to sham group (21.80 ± 5. 07 vs 0.80 ± 0. 45, P ＜ 0. 01 ). Conclusion mir-326 and mir-34a may play a key role in trauma-induced neural stem cells proliferation in hippocampus in vivo by targeting notch1 signaling.