牛MAGEL2的基因结构及在组织和胎盘中印记状态分析

Gene Structure and Genomic Imprinting Status of MAGEL2 in Different Tissues and Placenta of Adult Cattle

本研究旨在揭示牛PWS/AS(Prader-willi syndrome/angelman syndrome)印记区域中的MAGEL2(Melanoma antigen-like gene 2)基因的结构特点及其在成年牛组织及胎盘中的印记状态。生物信息学软件分析发现,牛MAGEL2基因位于21号染色体,为单外显子蛋白编码基因,编码长为1183个氨基酸的多肽序列,其产物为MAGE家族成员之一。构建MAGEL2基因的进化树,发现牛MAGEL2基因与羊相似性最高。MAGEL2在不同物种之间具有较高的保守性。应用基于单核苷酸多态性(single nucleotide polymorphisms,SNP)的RTPCR产物直接测序的方法分析MAGEL2在牛8个组织和器官(心,肝,脾,肺,肾,肌肉,脂肪和大脑)及胎盘的印记状态。比较杂合牛基因组PCR产物和RT-PCR产物在SNP位点的测序结果发现,MAGEL2基因在成年牛组织及胎盘中均为单等位表达,提示MAGEL2基因在牛中是印记的。

The purpose of this study is to reveal gene structural characteristics and imprinting status of MAGEL2(melanoma antigen-like gene 2)in the PWS/AS(Prader-willi syndrome/angelman syndrome)imprinting domain in adult cattle tissues and placenta.The analysis of bioinformatics software shows that MAGEL2 gene located on chromosome 21,is a single exon protein coding gene and encodes a polypeptide sequence of 1183 aa.Its product is a member of MAGE family.Constructing cladogram tree of the bovine MAGEL2 cDNA sequences of several species,found that the highest similarity between cattle and sheep.MAGEL2 is highly conserved among different species.Based on single nucleotide polymorphisms(SNP)and analyzed the imprinting status of MAGEL2 in different tissues(heart,liver,spleen,lung,kidney,muscle,fat and brain)and placenta of adult cattle by RT-PCR.The RT-PCR result displayed that MAGEL2 is expressed in 8 tissues,organs and placena.The monoallelic expression of MAGEL2 was confirmed by sequencing the genomic DNA and the cDNAs of heterozygous individuals.Sequencing results revealed that eight tissues and placenta are all expressed from a parental allele.These results suggesting that MAGEL2 was imprinted in adult cattle tissues and placenta.