miRNA的生物合成过程

The Biogenesis of miRNAs

MicroRNA(miRNA)是一类真核生物内源性的小分子单链RNA,通常为18～25nt长,能够通过与靶mRNA特异性的碱基配对引起靶mRNA的降解或者抑制其翻译,从而对基因进行转录后的表达调控.近几年来,在动物细胞和植物组织中,上百种miRNA被陆续发现.这些小分子调控RNA是从60～200nt的具有发夹状结构的前体中被切割出来而成熟的,在动物细胞中,miRNA基因的转录初产物(pri-miRMA)很快被一种核糖核酸酶ⅢDrosha加工成为miRNA前体(pre-miRNA),然后由细胞核转运至细胞质中,经另一种核糖核酸酶ⅢDicer识别剪切为成熟miRNA.对这一过程进行了简要的综述,并且对植物miRNA的成熟过程也进行了探讨.对miRNA的生物合成过程的深入了解,将有助于研究这一类起重要调控作用的RNA是如何行使功能的,从而进一步研究其在生长发育及各种疾病中所起的重要作用.

MicroRNAs （miRNAs） are endogenous single-stranded RNAs of 18～25 nt in eukaryotic organisms, which can regulate the complementary mRNAs at the post-transcriptional level through cleavage or translational repression of the mRNA targets. Recent years, several hundred miRNAs from animals and plants have been identified. These small modulatory RNAs are cleavaged from a precursor of 60～200 nt RNA hairpin. In animals, the primary transcripts of miRNA genes （pri-miRNAs） are recognized and cleaved into precursor miRNAs （pre-miRNAs） soon by an RNase Ⅲ family nuclease, Drosha; then, pre-miRNAs are transported from the nucleus to the cytoplasm. Once in the cytoplasm, pre-miRNAs are recognized and processed into their mature form by another RNase Ⅲ, Dicer. The procedure is briefly summarized, and the biogenesis of plant miRNAs is also dis＇cussed. Further research on the pathway of miRNA maturation can help us to know the mechanism of these small RNAs acted as important regulators, and can investigate their critical roles during development and disease.