Characterization and expression pattern of the novel MIA homolog TANGO

A novel human gene, TANGO, encoding a MIA ('melanoma inhibitory activity') homologous protein was identified by a gene bank search. TANGO, together with the homologous genes MIA, OTOR (FPD, MIAL) and MIA2 define a novel gene family sharing important structural features, significant homology at both the nucleotide and protein level, and similar genomic organization. The four members share 34-45% amino acid identity and 47-59% cDNA sequence identity. TANGO encodes a mature protein of 103 amino acids in addition to a hydrophobic secretory signal sequence. Sequence homology confirms the highly conserved SH3 structure present also in MIA, OTOR and MIA2. Thus, it appears that there are a number of extracellular proteins with SH3-fold like structures. Interestingly, in situ hybridization, RT-PCR and Northern Blots revealed very broad TANGO expression patterns in contrast to the highly restricted expression patterns previously determined for the other members of the MIA gene family. The only cells lacking TANGO expression are cells belonging to the hematopoetic system. High levels of TANGO expression were observed both during embryogenesis and in adult tissues.     

2P1, a novel male mouse cDNA specifically expressed during meiosis

We screened a mouse germinal cell expression library with a probe derived from Sob1, a human testis-specific cDNA, and identified 2P1, a new mouse cDNA. A database search revealed that 2P1 was 91% identical to ORF1 of E3-3, a rat gene probably involved in the regulation of alternative splicing. Sequencing showed that 2P1 has a destabilization motif in its 3'-untranslated region. Northern blotting showed strong gene expression in the testis and weak expression in the epididymis, with no signal detected in other tissues. RT-PCR analysis confirmed testis and epididymis expression. In situ hybridization revealed that 2P1 mRNA was absent in spermatogonia but expressed in spermatocytes. This last result was confirmed by RT-PCR of FACS isolated primary spermatocytes (pachytene stage). Using RT-PCR, purified spermatids were also shown to express 2P1.     

人SDCT2基因的两种不同转录产物选择性转录机理分析

为了克隆人高亲和力钠离子依赖性二羧酸转运蛋白 (highaffinitysodium dependentdicarboxylatetransporter,SDCT2 ,或NaDC3)基因并研究其生理功能 ,用大鼠SDCT2基因序列作为电子杂交探针对人EST数据库进行电子筛选 ,得到了一系列与大鼠SDCT2序列具有高度同源性的人EST序列 ,将它们拼接成 2个基因重叠群 ,设计特异性PCR引物通过RT PCR扩增得到 2条杂交探针用于筛选人肾cDNA文库 .从肾组织中同时克隆出了人SDCT2基因 2种mRNA变异体的全长cDNA(SDCT2α和SDCT2 β) ,两者 5′端前 3435bp序列完全一致 ,但 3′端长度不同 ,SDCT2 β在第 3435bp以后比SDCT2α多出了 5 85bp的序列 .Northern杂交和RT PCR显示 ,SDCT2α在人肾中的表达丰度最高 ,在肝、脾、胎盘、脑及结肠中也有低水平的表达 .而SDCT2 β主要在肾脏中表达 ,在脾也有低水平的表达 .基因组结构分析表明 ,虽然两种mRNAs均由 13个外显子组成 ,但是SDCT2α的第 13外显子含有 1个poly(A)加尾信号AATAAA ,而SDCT2 β的第 13外显子含有 2个poly(A)加尾信号 .这表明在肾脏和脾脏组织中 ,人SDCT2基因可能通过选择性使用位于第 13外显子不同位置的 2个poly(A)信号而转录出 2种不同长度的mRNA变异体 .