miR-9和miR-9＊在SAMP8小鼠衰老中的功能及机制

Functions of miR-9 and miR-9* during Aging in SAMP8 Mice and Their Possible Mechanisms

目的探讨miR-9和miR-9*在SAMP8小鼠衰老中的功能及机制。方法选取4-、8-、12-月龄快速老化倾向小鼠(SAMP8)作为研究对象,并以同月龄快速老化抵制小鼠(SAMR1)为对照,每组3只,取脑,切片进行原位杂交检测miR-9和miR-9*的表达;分别以miR-9和miR-9*的模拟物和抑制物转染N2a细胞,采用流式细胞术检测过表达和敲低miRNA对细胞周期的影响;生物信息学预测miR-9和miR-9*靶基因并进行双荧光素酶报告基因实验验证。结果 miR-9和miR-9*在SAMP8小鼠海马区的表达低于SAMR1小鼠。敲低miR-9和miR-9*都可以增加N2a细胞G1期细胞在群体中的比例,减少S期细胞在群体中的比例,过表达则相反。生物信息学预测并通过文献筛选miR-9的靶基因有PSEN1、SCN2B、MAP3K3和BACE1,miR-9*的靶基因有CDKn1c。荧光素酶报告基因实验证实miR-9的靶基因是MAP3K3,miR-9*的靶基因是CDKn1c。结论 miR-9和miR-9*可能是分别通过其靶基因MAP3K3和CDKn1c在SAMP8小鼠衰老进程中发挥重要作用。

Objective To explore the functions of miR-9 and miR-9＊in SAMP8 mice during the aging and their possible mechanisms. Methods SAMP8 mice（ 4-,8-,12-month old,respectively） were selected,three age-matched SAMR1 mice were used as the control group with three mice in each group. The brains were collected and then sectioned for in situ hybridization of miR-9 and miR-9＊. Mimics or inhibitors of miR-9 and miR-9＊were transfected into N2 a cells,and the effects of overexpression or knockdown of the microRNAs on the cell cycle were detected by flow cytometry. Target genes were predicted by bioinformatic analysis and confirmed by dual luciferase assay. Results Expressions of miR-9 and miR-9＊in hippocampus of SAMP8 mice were lower than those of SAMR1 mice. Knockdown of miR-9 and miR-9＊induced a prolonged G1 phase and a shortened Sphase in N2 a cells; in contrast,miR-9 and miR-9＊overexpression showed opposite effects. The predicted target genes of miR-9 were PSEN1,SCN2 B,MAP3K3,and BACE1,and that of miR-9＊was CDKn1 c. Dual luciferase reporter gene assay showed that miR-9 targeted MAP3K3 while miR-9＊targeted CDKn1 c. Conclusion miR-9 and miR-9＊play an important role during aging via the target genes MAP3K3 and CDKn1 c in the SAMP8 mice.