microRNA125对无义突变的人凝血因子Ⅸ基因调控的分子机制

OBJECTIVE: To construct human coagulation factor Ⅸ mini-gene (Mini-hF9) and some nonsense mutants, detect the levels of the Mini-hF9 mRNA, and analyze the molecular mechanism of microRNA125 regulating F9 gene with nonsense mutation. METHODS: Three nonsense mutants were obtained by using PCR mutagenesis to analyze the mechanism of plasma thromboplastin component recognition. The Mini-hF9 gene mRNA levels were detected by Real-time PCR in mammalian cells co-transfected with nonsense mutant expression vectors and miR-125 mimics. RESULTS: Mini-hF9 gene was constructed successfully and cloned into the mammalian expression vector. The only normal transcript was detected in cells transfected with the Mini-hF9 gene expression vectors. Three nonsense mutants, M1 (nt 34 G>T in Exon 7), M2 (nt 52 G>T in Exon 7) and M3 (nt 85 G>T in Exon 7), were obtained by using PCR mutagenesis. The levels of the Mini-hF9 mRNA decreased to 14.1% (t=15.464, P=0.004) in M1 and 22.4% (t=15.755, P=0.004) in M2 mutants after transfection, respectively. It was proved to be caused by nonsense-mediated mRNA decay (NMD) in CHX experiment. The levels of Mini-hF9 mRNA increased to 1.70 times (t=−4.883, P=0.039) and 2.40 times (t=−17.537, P=0.003) in M1 mutant after miR-125a or miR-125b mimics treatment, respectively. The levels of Mini-hF9 mRNA increased to 2.02 times (t=−19.264, P=0.003) and 2.07 times (t=−9.158, P=0.012) in M2 mutant after miR-125a or miR-125b mimics treatment, respectively. CONCLUSION: Nonsense mutant location is a key determinant for triggering NMD. MicroRNA125 could improve the stability of Mini-hF9 mRNA in M1 and M2 mutants by repressing NMD. MicroRNA125, a short non-coding RNA molecule, could be a potential therapeutic target in conditions caused by the NMD pathway.