昆明動物所宿兵實(shí)驗(yàn)室最近通過對靈長類代表物種的研究，發(fā)現(xiàn)了一個由Alu介導(dǎo)產(chǎn)生并快速復(fù)制的microRNA家族。這個家族位于人類19號染色體上,，在胎盤和胎兒大腦中優(yōu)勢表達(dá)。在靈長類的進(jìn)化過程中,，這個家族在Alu的介導(dǎo)下,，不斷通過基因重復(fù)產(chǎn)生新的拷貝，且拷貝數(shù)在靈長類物種間存在很大差異(8－85個拷貝),。
序列比較表明,，物種內(nèi)和物種間microRNA的序列分歧相似；同時,，在各個靈長類分支中均存在基因拷貝的獲得和丟失,，也存在基因的假基因化。由此表明,，這個miroRNA家族在靈長類中經(jīng)歷了典型的“生－死”(Birth and Death)進(jìn)化歷程,。它暗示這個家族的microRNA基因在靈長類的進(jìn)化中其功能可能發(fā)生了多樣化，以適應(yīng)不同靈長類物種在發(fā)育過程中的需要,。
microRNA是近年發(fā)現(xiàn)的在基因組中廣泛存在的一類小的,、非蛋白編碼基因。它通過與mRNA中特定的互補(bǔ)位點(diǎn)結(jié)合來調(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程,。另外，在靈長類基因組中存在一類中等重復(fù)序列－Alu,。它是靈長類特有的重復(fù)序列,，對靈長類基因組的演化具有深遠(yuǎn)的影響。
這一研究結(jié)果將為科研人員更好地了解Alu對靈長類基因組進(jìn)化的影響以及非蛋白編碼基因的進(jìn)化模式提供嶄新的視角,。研究結(jié)果已發(fā)表于分子進(jìn)化領(lǐng)域國際知名刊物《分子生物學(xué)與進(jìn)化》（Molecular Biology and Evolution）上,。（來源：中科院昆明動物所）
生物谷推薦原始出處：
（Molecular Biology and Evolution），doi:10.1093/molbev/msn094,，Rui Zhang, Yin-Qiu Wang, and Bing Su
Molecular evolution of a primate-specific microRNA family
Rui Zhang*,,, Yin-Qiu Wang*, and Bing Su*,
* State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
Kunming Primate Research Center, Chinese Academy of Sciences, Kunming 650223, China
Graduate School of Chinese Academy Sciences, Beijing 100039, China
Received for publication March 7, 2008. Revision received April 9, 2008. Accepted for publication April 10, 2008.
Lineage-specific microRNA (miRNA) families may contribute to developmental novelties during evolution. However, little is known about the origin and evolution of new miRNA families. We report evidence of an Alu-mediated rapid expansion of miRNA genes in a previously-identified primate-specific miRNA family, drawn from sequencing and comparative analysis of nine diverse primate species. Evolutionary analysis reveals similar divergence among miRNA copies whether they are within or between species, lineage-specific gain and loss of miRNAs, and gene pseudolization in multiple species. These observations support a birth-and-death process of miRNA genes in this family, implicating functional diversification during primate evolution. In addition, both secondary structure conservation and reduced SNP density attest to functional constraint of this family in primates. Finally, we observed preferential expression of miRNAs in human placenta and fetal brain, suggesting a functional importance of this family for primate development.
