基因组印迹基因及其生物学意义

GENOMIC IMPRINTED GENE AND ITS BIOLOGICAL SIGNIFICANCE

基因组印迹(genomic imprniting)是指在配子或合子发生期间,来自亲本的等位基因或染色体在发育过程中产生专一性的加工修饰,导致后代体细胞中两个亲本来源的等位基因有不同的表达活性,为一种后生论修饰。目前在人类和小鼠中鉴定的印迹基因已超过25个,它们具有一些共同的特点,如印迹基因分布的群集性、复制的不同步性、表达的时空特异性、遗传的保守性及编码RNAs等。基因组印迹的分子机理与印迹基因的甲基化尤其是CpG岛甲基化密切相关,特异性甲基化区域在印迹基因的表达中具有重要作用。基因组印迹基因与胎儿和胎盘的生长发育及细胞增殖有关,正常印迹的改变可引起包括肿瘤在内的多种遗传性疾病。

Genomic imprinting is an epigenetic modification of a specific parental allele of a gene, or the chromosome on which is resides, in the gamete or zygote, leading to differential expression of the two alleles of the gene in somatic cells of the offspring. There are now more than 25 identified imprinted genes in human and mice. They have some common features such as clustering of imprinted genes, asynchrony of DNA replication of imprinted genes, temporal and spatial regulation of genomic imprinting, conservation of imprinting and imprinted genes code for RNAs. The molecular mechanisms of genomic imprinting is relative to DNA methylation of the imprinted genes especially CpG dinucleotides methyla-tion closely. Differentially methylated regions ( DMRs) are important for the expression of imprinted genes. Imprinted genes are involved in fetal and placental growth and cell proliferation, and the alteration of normal imprinting patterns gives rise to numerous human genetic disease including cancer.