RNA interference

The process of RNA-interference in eukaryotic cells. Long precursor microRNA (miRNA), called pri-miRNA, is cleaved by RNase III endonuclease (Drosha) into pieces of approximately 70 nucleotides each (called pre-miRNA) in the nucleus. Following transportation into the cytoplasm by exportin 5 another RNase III endonuclease (Dicer) cleaves it into mature miRNA segments. Degradation of messenger RNA (mRNA) and translational repression occurs after miRNA binds to the RNA-induced silencing complex (RISC). Cytoplasmic long double-stranded RNA (dsRNA) is cleaved by Dicer into small interfering RNA (siRNA), which is incorporated into RISC, resulting in the cleavage and degradation of specific target mRNA. Synthetic double-stranded siRNA is not processed by Dicer and directly incorporated by the RISC.

真核细胞中RNA干扰的过程。长前体微小RNA（miRNA），被称为pri-miRNA，在细胞核内被RNase III内切酶（Drosha）切割成约70个核苷酸大小的片段（称为pre-miRNA）。随后，通过exportin 5转运至细胞质中，另一RNase III内切酶（Dicer）将其切割成成熟的miRNA片段。miRNA与RNA诱导的沉默复合体（RISC）结合后，发生信使RNA（mRNA）的降解和翻译抑制。细胞质中的长双链RNA（dsRNA）被Dicer切割成小干扰RNA（siRNA），并纳入RISC中，导致特定目标mRNA的切割和降解。合成的双链siRNA未经Dicer处理，而直接被RISC纳入。