Long Jian-Er, Chen Hai-Xuan
Laboratory of Medical Microbiology, Department of Medical Microbiology and Parasitology, Shang Medical College of Fudan University, 138 Yixueyuan Road, Shanghai, People's Republic of China.
Biochem Genet. 2009 Jun;47(5-6):329-43. doi: 10.1007/s10528-009-9234-6. Epub 2009 Mar 7.
MicroRNAs (miRNA) are a class of noncoding RNA molecules that regulate gene expression by an RNA-interfering pathway through cleavage or inhibition of the translation of target mRNA. The 254 cattle miRNA candidates found by homology searching frequently clustered at certain chromosomes, and some are possibly expressed from more than one genomic locus. They were partially verified by cloning from a small cattle RNA library, where 31 distinct miRNAs were identified: 18 previously registered in the database of miRBase, 11 novel and homologous to known mammalian miRNAs, and 2 potentially novel without homology to any known miRNAs. Partial miRNA expression was detected by RT-PCR in cattle tissues, such as brain, liver, lung, and heart; some were expressed in all tissues and others in a specific tissue. Sequence alignments revealed that many had end variants, most of which differed in the 3' end; a small number differed in the 5' end. This indicates that the same miRNA gene can be individually modified in the process of miRNA biogenesis and could have a different role in regulating target gene expression.
微小RNA（miRNA）是一类非编码RNA分子，其通过RNA干扰途径，通过切割或抑制靶mRNA的翻译来调节基因表达。通过同源性搜索发现的254个牛miRNA候选物经常聚集在某些染色体上，其中一些可能从多个基因组位点表达。它们通过从小牛RNA文库中克隆得到部分验证，在该文库中鉴定出31种不同的miRNA：18种先前已在miRBase数据库中注册，11种与已知哺乳动物miRNA同源的新miRNA，以及2种与任何已知miRNA均无同源性的潜在新miRNA。通过RT-PCR在牛组织（如脑,肝,肺和心脏）中检测到部分miRNA表达；一些在所有组织中表达，而另一些在特定组织中表达。序列比对显示，许多miRNA具有末端变体，其中大多数在3'末端不同；少数在5'末端不同。这表明相同的miRNA基因在miRNA生物合成过程中可以被单独修饰，并且在调节靶基因表达中可能具有不同的作用。
