致唐氏综合征胎儿大脑皮质发育异常的HC21基因的筛查和鉴定

Screening and identification of human chromosome 21 genes resulting in abnormal development of fetal cerebral cortex with Down syndrome

目的通过比较唐氏综合征(DS)和正常胎儿大脑皮质中的基因差别表达模式,初步筛选出与 DS 大脑皮质发育异常、乃至与智力低下发生密切相关的人类21号染色体基因(HC21),为搭建21三体(T21)智力低下发生的分子网络奠定基础。方法利用 Affymetrix U133A 基因芯片分析HC21基因在20周 DS 和正常胎儿大脑皮质中的差别表达模式,利用半定量 RT-PCR 和反向 Northern印迹杂交对筛选出的 HC21基因进行鉴定。结果 Affymetrix U133A 芯片含有127个已知的 HC21基因,其中在两类大脑皮质中均不表达的有56个。在两类组织中均表达的71个 HC21基因中,表达上调1.4倍以上的 HC21基因有27个,表达下调1.5倍以上的有两个。对99个 HC21基因所进行的半定量 RT-PCR 和/或反向 Northern 印迹杂交分析也得到了一致的结果。结论在 DS 和正常胎儿脑组织中差别表达的 HC21基因可能就是造成 DS 脑组织结构和功能发育异常的根本原因,也是引发智力低下的重要的候选基因,对这些基因分子作用通路的深入研究是全面揭示 DS 胎儿大脑皮质发育异常乃至智力低下发生分子机制的基础。

Objective To screen the candidate human chromosome 21 （HC21） genes related to mental retardation （MR）. Methods The expression of 127 known HC21 genes in the cerebral cortex specimen of a DS fetus and the specimen of a non-DS fetus induced due to maternal disease was detected with Affymetrix U133A gene chip. Semi-quantitative RT-PCR and reverse Northern blotting were used to identify the HC21 genes thus screened. Results Fifty-six of the 127 known HC21 genes were not expressed in both the specimens from the DS and control fetuses, while 71 of the 127 HC21 genes were expressed in both of them. The expression of 57 of these 71 genes was up-regulated and 14 of the 71 genes was downregulated in the DS fetal cerebral cortex compared with the non-DS control. The expression of these 71 genes was upregulated by 1.5 times and the expression of 2 genes was downregulated by 1.5 times. 21 candidate key genes were thus provided. Conclusion Twenty-one HC21 genes are involved in the MD of DS.