Evolution and Distribution of Teleost myomiRNAs: Functionally Diversified myomiRs in Teleosts
Evolution and Distribution of Teleost myomiRNAs: Functionally Diversified myomiRs in Teleosts
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DOI：
10.1007/s10126-016-9705-9
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发表时间：
2016-06-01
影响因子：
3
通讯作者：
Watabe, Shugo
中科院分区：
文献类型：
--
作者：
Siddique, Bhuiyan Sharmin;Kinoshita, Shigeharu;Watabe, Shugo
肌球蛋白重链（MYH）基因是一个多基因家族，每个成员的表达调控决定了肌肉的生理和收缩特性。其中，MYH 6、MYH 7和MYH 14在哺乳动物MYH基因家族中占据独特的位置，这是因为它们在慢肌/心肌中的特异性表达和内含子微（mi）RNA的存在。MYH 6、MYH 7和MYH 14分别编码miR-208 a、miR-208 b和miR-499。这些MYH编码的miRNA由于其肌肉特异性表达和功能而被指定为myomiR。在哺乳动物中，myomiRs和宿主MYH形成参与肌纤维类型特化的转录网络;因此，它们的基因组位置和表达模式非常保守。然而，我们先前的研究揭示了MYH 14/miR-499在硬骨鱼中的不同分布和表达，表明myomiRs和宿主MYH在硬骨鱼中的独特进化。在这里，我们研究了myomiRs和主机MYH在各种硬骨鱼物种的分布和表达。硬骨鱼类中主要的心脏MYH亚型是一个无内含子基因，心房肌球蛋白重链（amhc）和心室肌球蛋白重链（vmhc）基因，编码一个内含子miRNA，miR-736。系统发育分析表明vmhc/miR-736是一种硬骨鱼特异性myomiR，不同于四足动物MYH 6/MYH 7/miR-208 s。硬骨鱼基因组中除了vmhc和amhc外，还含有种特异性的直系同源物，这表明在硬骨鱼进化过程中发生了复杂的基因重复和基因丢失事件。在青鳉和torafugu中，miR-499在慢肌/心肌中高度表达，而miR-736的表达非常低，并且不是肌肉特异性的。这些结果表明，随着宿主MYH的多样化，硬骨鱼类中myomiRs的功能也发生了变化。
Myosin heavy chain (MYH) genes belong to a multigene family, and the regulated expression of each member determines the physiological and contractile muscle properties. Among these, MYH6, MYH7, and MYH14 occupy unique positions in the mammalian MYH gene family because of their specific expression in slow/cardiac muscles and the existence of intronic micro(mi) RNAs. MYH6, MYH7, and MYH14 encode miR-208a, miR-208b, and miR-499, respectively. These MYH encoded miRNAs are designated as myomiRs because of their muscle-specific expression and functions. In mammals, myomiRs and host MYHs form a transcription network involved in muscle fiber-type specification; thus, genomic positions and expression patterns of them are well conserved. However, our previous studies revealed divergent distribution and expression of MYH14/miR-499 among teleosts, suggesting the unique evolution of myomiRs and host MYHs in teleosts. Here, we examined distribution and expression of myomiRs and host MYHs in various teleost species. The major cardiac MYH isoforms in teleosts are an intronless gene, atrial myosin heavy chain (amhc), and ventricular myosin heavy chain (vmhc) gene that encodes an intronic miRNA, miR-736. Phylogenetic analysis revealed that vmhc/miR-736 is a teleost-specific myomiR that differed from tetrapoda MYH6/MYH7/miR-208s. Teleost genomes also contain species-specific orthologs in addition to vmhc and amhc, indicating complex gene duplication and gene loss events during teleost evolution. In medaka and torafugu, miR-499 was highly expressed in slow/cardiac muscles whereas the expression of miR-736 was quite low and not muscle specific. These results suggest functional diversification of myomiRs in teleost with the diversification of host MYHs.