小鼠SmX5基因mRNA的选择性剪接(英文)

Identification of Alternate Splice Variants for Murine SmX5

通过RT PCR技术 ,发现小鼠SmX5基因的另外 3种选择性剪接体 ,分别命名为SmX5a、b和c。小鼠SmX5acDNA具有完整的内含子 1,而SmX5bcDNA含有部分内含子 2。SmX5c的保留片断和SmX5b在相同位置起始 ,但保留部分延伸经过余下的内含子 2。余下的DNA序列在所有内含子 外显子边界处都符合剪接的“GT AG”规则。RT PCR的表达分析显示这 3种异构体都是稳定的转录产物 ,均通过剪接体特异性引物的PCR反应在mRNA水平上得到证实。和SmX5相比较 ,剪接体的出现频率都很低。RT PCR表达分析提示 ,SmX5和它的 3种异构体存在于小鼠的脑、肾、睾丸、胸腺、肝、脾和心脏。SmX5a主要在胸腺中表达 ,而SmX5b和c在所有组织都可以检测到。SmX5不同选择剪接体及其组织特异的不同剪接方式的存在 ,表明SmX5的表达是复杂的 ,并且所有 4种SmX5mR

We report here the identification of three additional murine SmX5 alternative transcripts,designated SmX5a,b and c .The cDNA of SmX5a possesses intron 1 in its entirety,and SmX5b harbors a part of intron 2.The retained fragment of SmX5c starts at the same position as SmX5b ,but the retention extends through the remaining portion of intron 2.The sequence of retained DNA at all the intron exon boundaries conforms to the 'GT AG' rule.RT PCR analysis indicates that the three isoforms are stable transcripts,all at low frequency when compared with SmX5 .Expression analysis by RT PCR indicates that SmX5 and its isoforms exist in murine brain,kidney,testis,thymus,liver,spleen and heart.The SmX5a isoform is predominantly expressed in the thymus,while SmX5b and c are expressed in all tissues examined.The presence of alternatively spliced SmX5 isoforms and tissue specific variation in splicing patterns suggests that SmX5 expression is complex and that the regulation of all four SmX5 mRNA levels may be critical in maintaining proper pre mRNA splicing machinery in different cell types.