MAD2、BUB1基因在自然流产染色体数目异常胚胎中的表达

目的:探讨MAD2、BUB1 mRNA及蛋白表达水平在人类胚胎染色体分离中的作用。方法:应用荧光原位杂交(fluorescence in situ hybridization,FISH)技术检测102例自然流产胚胎绒毛染色体数目,将自然流产胚胎分为染色体数目正常组和异常组,分别用RT-PCR和Western blotting检测胚胎绒毛组织中MAD2、BUB1 mRNA和蛋白质相对表达水平。结果:①102例自然流产胚胎中检出染色体数目异常50例(49.02%),其中多倍体9例、非整倍体36例、嵌合型5例。②异常组胚胎绒毛中MAD2 mRNA及蛋白相对表达水平分别为0.89±0.19和0.45±0.06,均明显高于正常组(0.80±0.21和0.42±0.08,P<0.05)。③异常组胚胎绒毛中BUB1 mRNA及蛋白相对表达水平分别为1.04±0.23和0.35±0.05,与正常组(0.98±0.25和0.33±0.07)比较,差异无统计学意义(P>0.05)。结论:胚胎染色体数目异常是导致自然流产的重要原因;MAD2在胚胎染色体数目异常组中高表达,延长了纺锤体组装检查点(SAC)的有丝分裂阻滞持续时间,在保证染色体正确分离、维持基因组稳定方面起重要作用。BUB1是SAC的上游基因,在延长有丝分裂阻滞中不起主要作用,但其正常表达对于SAC发挥功能必不可少。

Expression of MAD2 and BUB1 mRNA and Protein in Human Spontaneous Abortion Embryos with Chromosomal Abnormality

Objective: To investigate expression levels of MAD2 and BUB1 and its possible role in the chromosome segregation.Methods: One hundred and two spontaneous abortion embryos were divided into two groups,one was normal and another was abnormal with chromosomal abnormality,by fluorescence in situ hybridization(FISH) technology detecting with 13,16,18,21,22,X and Y chromosome specific probes.Expressions of MAD2 and BUB1 on the chorionic villi was detected by RT-PCR and Western blotting.Results: There were 50 cases with abnormal chromosome detected in 102 embryos of spontaneous abortion,the rate was 49.02%.Nine cases belonged to polyploid,36 cases were aneuploidy,and 5 cases were mosaicism.Expression of MAD2 mRNA and protein in chorionic villus of embryos with chromosomal abnormality(0.89 ± 0.19 and 0.45 ± 0.06) were significantly higher than those in embryos with normal chromosome(0.80 ± 0.21 and 0.42 ± 0.08,P<0.05),respectively.There was no significant difference in expression of BUB1 mRNA and protein between chorionic villus of embryos with chromosomal abnormality(1.04 ± 0.23 and 0.35 ± 0.05) and embryos with normal chromosome(0.98 ± 0.25 and 0.33 ± 0.07).Conclusion: Overexpression of MAD2 in embryos with chromosomal abnormality may prolong duration of mitosis by delaying satisfaction of the spindle assembly checkpoint.MAD2 overexpression may play an important role in separating chromosomes exactly into two daughter cells and maintenance of genomic integrity.BUB1,which is an upstream gene of SAC,can’t play a centre role in prolonging duration of mitosis,however,its normal expression is vital for SAC function.