中科院昆明動(dòng)物所宿兵研究小組最近通過(guò)對(duì)靈長(zhǎng)類代表物種的研究,，發(fā)現(xiàn)了一個(gè)快速進(jìn)化的microRNA家族。這個(gè)家族位于X染色體上,，并在睪丸中優(yōu)勢(shì)表達(dá),。在靈長(zhǎng)類的進(jìn)化過(guò)程中，這個(gè)家族不斷通過(guò)基因重復(fù)產(chǎn)生新的拷貝,，且拷貝數(shù)在靈長(zhǎng)類物種間存在差異,。同時(shí)，這個(gè)家族的microRNA序列變異的速度明顯高于基因組中已知microRNA基因的平均水平,，從而導(dǎo)致一些物種特異的microRNA基因的產(chǎn)生,。以前的很多研究表明，在靈長(zhǎng)類的進(jìn)化中,，與雄性生殖相關(guān)的蛋白編碼基因由于受到很強(qiáng)的選擇,，進(jìn)化速度很快。宿兵研究員實(shí)驗(yàn)室的研究結(jié)果證實(shí),，除蛋白編碼基因以外,，microRNA基因也會(huì)受到達(dá)爾文正選擇的影響，發(fā)生快速的進(jìn)化,。這一研究結(jié)果將為我們更為全面地了解非蛋白編碼基因的進(jìn)化模式及其在功能進(jìn)化中的作用提供嶄新的視角,。研究結(jié)果發(fā)表于基因組學(xué)國(guó)際知名刊物——Genome Research上(http://www.genome.org/papbyrecent.shtml
microRNA是近年發(fā)現(xiàn)的在基因組中廣泛存在的一類小的、非編碼基因,。它通過(guò)與mRNA中特定的互補(bǔ)位點(diǎn)結(jié)合來(lái)調(diào)節(jié)蛋白編碼基因的表達(dá)和翻譯,，從而參與發(fā)育的精細(xì)調(diào)控等一系列重要的生命過(guò)程,。目前，絕大多數(shù)已知的microRNA在序列上都很保守,，表明其承擔(dān)著重要的生物學(xué)功能,。然而，基因組中也可能存在快速進(jìn)化的microRNA, 并在新的表型和功能的產(chǎn)生中發(fā)揮作用,。
部分英文原文：
Published online before print April 6, 2007
Genome Research, DOI: 10.1101/gr.6146507
Letter
Rapid evolution of an X-linked microRNA cluster in primates
Rui Zhang1,2,3, Yi Peng1,2, Wen Wang1, and Bing Su1,2,4
1 Key Laboratory of Cellular and Molecular Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China; 2 Kunming Primate Research Center, Chinese Academy of Sciences, Kunming 650223, China; 3 Graduate School of Chinese Academy Sciences, Beijing 100039, China
MicroRNAs (miRNAs) are a growing class of small RNAs (about 22 nt) that play crucial regulatory roles in the genome by targeting mRNAs for cleavage or translational repression. Most of the identified miRNAs are highly conserved among species, indicating strong functional constraint on miRNA evolution. However, nonconserved miRNAs may contribute to functional novelties during evolution. Recently, an X-linked miRNA cluster was reported with multiple copies in primates but not in rodents or dog. Here we sequenced and compared this miRNA cluster in major primate lineages including human, great ape, lesser ape, Old World monkey, and New World monkey. Our data indicate rapid evolution of this cluster in primates including frequent tandem duplications and nucleotide substitutions. In addition, lineage-specific substitutions were observed in human and chimpanzee, leading to the emergence of potential novel mature miRNAs. The expression analysis in rhesus monkeys revealed a strong correlation between miRNA expression changes and male sexual maturation, suggesting regulatory roles of this miRNA cluster in testis development and spermatogenesis. We propose that, like protein-coding genes, miRNA genes involved in male reproduction are subject to rapid adaptive changes that may contribute to functional novelties during evolution.
4 Corresponding author.
E-mail [email protected] ; fax 86-871-5193137.
