马传染性贫血病毒受体选择性剪接异构体的鉴定与分析

摘要

Alternative splicing is an important mechanism of post-transcriptional regulation, which increases transcriptome and proteome diversifications by generating multiple mRNA products from a specific gene. The equine lentivirus receptor 1 (ELR1) was found as the only receptor for equine infectious anemia virus (EIAV) and identified as a member of the tumor necrosis factor receptor (TNFR) superfamily. To investigate the alternative splicing of ELR1, cDNA clones of the receptor were constructed from the total RNA extracted from cultured primary equine macrophages. Sequence analysis of these clones revealed two major types of alternative splicing variants of ELR1, i.e., one type with an insertion (ELR1-IN) and the other with a deletion (ELR1-DE) in the coding region. ELR1-IN contained an insert of 153 bp between the 786 nt to 787 nt of the published ELR1 cDNA sequence, and ELR1-DE had a deletion of 64 bp between the sites of 415 nt to 478 nt. Both of these changes of sequence shifted the open reading frame of ELR1. Especially, the insertion resulted in the termination of translation at the site upstream of the transmembrane domain of the receptor, and encoded a soluble ELR1. This work provides a new insight for the interaction between EIAV and host.%马慢病毒受体1 (ELR1)是马传染性贫血病毒(ELAV)唯一受体,属于肿瘤坏死因子受体超家族.为研究ELR1 mRNA选择性剪接的状况,本研究从EIAV靶细胞的巨噬细胞中提取RNA,经RT-PCR扩增并克隆测序.结果显示,ELR1 mRNA具有不同形式的选择性剪接异构体,主要表现为插入和缺失形式.插入片段为153bp,位于序列的786nt～787nt之间,而缺失型异构体丢失了ELR1序列的415nt～478nt.不论序列的插入或缺失,均导致该基因编码框移位.特别是插入型异构体,编码框在跨膜区之前遇到终止密码子,造成翻译的提前终止,推测产生截短的可溶性ELR1.这些剪接异构体的鉴定为研究EIAV与机体的相互作用提供了新的研究方向.