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

ABSTRACT

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 N2a 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 S phase in N2a cells;in contrast,miR-9 and miR-9(*) overexpression showed opposite effects. The predicted target genes of miR-9 were PSEN1,SCN2B,MAP3K3,and BACE1,and that of miR-9(*) was CDKn1c. Dual luciferase reporter gene assay showed that miR-9 targeted MAP3K3 while miR-9(*) targeted CDKn1c. CONCLUSION: miR-9 and miR-9(*) play an important role during aging via the target genes MAP3K3 and CDKn1c in the SAMP8 mice.