Figure 5. Possible Mechanisms of miRISC-Mediated Repression.
Nonrepressed mRNAs recruit initiation factors and ribosomal subunits and form circularized structures that enhance translation (top). When miRISCs bind to mRNAs, they can repress initiation at the cap recognition stage (upper left) or the 60S recruitment stage (lower left). Alternatively, they can induce deadenylation of the mRNA and thereby inhibit circularization of the mRNA (bottom). They can also repress a postinitiation stage of translation by inducing ribosomes to drop off prematurely (lower right). Finally, they can promote mRNA degradation by inducing deadenylation followed by decapping.