类固醇5-α还原酶样基因Srd5α2l2的克隆及表达分析

Molecular Cloning and Expression Analysis of Srd5α2l2: a Novel Mouse Member of Steroid 5 Alpha-reductase Family

采用表达序列标签 (EST)介导的基因克隆和表达谱分析 ,从小鼠心脏克隆了一个cDNA为 2 3 4 8bp ,主要在心脏表达的新基因Srd5α2l2 (GenBankAccNo .AF5483 65) .该基因由 12个外显子组成 ,3′非翻译区富含ATTTA序列 ,最大开放阅读框编码一个由 3 61个氨基酸组成的假定蛋白 ,该蛋白质C端含有类固醇 5 α还原酶的保守结构域 (3 oxo 5 alpha steroid 4 dehydrogenase ,STEROID_DH ) .生物信息学分析表明 ,人cDNA克隆DKFZp3 13D0 82 9(AL83 3 10 8)是Srd5α2l2的人同源基因 .经同源性检索 ,支持Srd5α2l2的全部 41条EST中 2 5条来自小鼠心脏组织 .RT PCR检测初步证实 ,该基因主要在心脏中表达 ,而在其他组织中不表达或弱表达 .综合考虑Srd5α2l2的序列特征和表达谱 。

A novel mouse heart-specific gene, Srd5α2l2, was cloned from mouse embryo heart by EST database searching and RT-PCR. The cDNA of Srd5α2l2 was 2 348 bp and composed of 12 extrons within over 77 kb in mouse genome. This gene was mapped to mouse chromosome 5 by BLAST search to mouse genome. Analysis of the 3′ untranslation region of the cDNA showed the presence of ATTTA sequence, which was believed to act as degradation signal of mRNA. The longest ORF spanned all of the 12 extrons and encoded a putative protein of 361 amino acids. A conserved steroid 5 alpha-reductase domain (3-oxo-5-alpha-steroid 4-dehydrogenase,STEROID_DH) was present at the C-terminus of the deduced protein. Homologous alignment found high identity of nucleotide sequence, deduced amino acid sequence and genomic structure between Srd5α2l2 and human cDNA of DKFZp313D0829(AL833108). It may be concluded that AL833108 was the human orthologue of Srd5α2l2. BLAST search showed that cDNA of Srd5α2l2 was supported by 41 ESTs from EST databa se, 25 out of the 41 ESTs were from mouse heart. RT-PCR performed on a panel of different mouse tissues demonstrated that Srd5α2l2 strongly expressed in mouse heart but not or much more weakly expressed in other tissues. These results suggested that Srd5α2l2 is a novel heart-specific member of steroid 5 alpha-reductase family. As far as it is known that no heart-specific member of this family was reported before.