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MicroRNAs(miRNAs)是大约22个核苷酸长度的非编码RNA,存在于几乎所有多细胞生物中。miRNA基因编码的pri-miRNA在细胞核内经Drosha酶切割后运输到胞浆内,并由Dicer酶切割而成熟,与宿主蛋白结合形成RNA诱导的沉默复合体,通过与靶mRNA的3’端非翻译区不完全互补结合,诱导靶信使RNA(messenger RNA,mRNA)降解或翻译抑制,从而调节蛋白表达。miRNA不易突变,特别是5’端的2～7或2～8个核苷酸(seed region)与靶mRNA完全互补,非常保守。miRNA几乎在所有生物过程中起作用,如细胞分化、增殖、凋亡、新陈代谢以及调节免疫。
MicroRNAs (miRNAs) are about 22 nucleotides in length of non-coding RNA present in almost all multicellular organisms. The miRNA-encoded pri-miRNA is cleaved by the Drosha enzyme in the nucleus and then transported to the cytoplasm. The pri-miRNA is cleaved by the Dicer enzyme to mature and bind to the host protein to form an RNA-induced silencing complex. The pri-miRNA, Regions are not completely complementary to each other and induce the inhibition of messenger RNA (mRNA) degradation or translation, thereby regulating the protein expression. MiRNAs are not easily mutated. In particular, the 2-7 or 2-8 nucleotide regions at the 5 ’end are completely complementary to the target mRNA and are very conserved. MiRNAs play a role in almost all biological processes, such as cell differentiation, proliferation, apoptosis, metabolism, and immune regulation.