RNA interference (RNAi)

  • RNAi has mainly two purposes:
    1. degrade hostile RNA from viruses and transposons (exogenous RNAi)
    2. regulate gene expression on a post-transcriptional level (endogenous RNAi)
  • Initially, double stranded miRNA/siRNA is cleaved into shorter fragments by the endoribonuclease enzyme Dicer.
  • Interaction complex that is formed by single stranded miRNA/siRNA, targeted mRNA and proteins is called “RNA induced silencing complex” (RISC).
  • The formation of the RISC will either result in degradation of target mRNA or in repression of translation of target mRNA.
    • mRNA is degraded if pairing of miRNA/siRNA is fully complementary.
    • Translation of mRNA is repressed/disturbed if pairing of miRNA is not fully complementary.