How mRna silencing take place

Gene silencing, often used in context of RNA interference (RNAi), is a regulatory pathway by which the expression of a gene is suppressed.  Although a gene may be silenced at the transcriptional or post-transcriptional stages, RNAi is specifically a post-transcriptional gene silencing (PTGS) mechanism achieved by cellular introduction of a double stranded RNA (dsRNA) termed siRNA or microRNA.

Gene silencing occurs naturally in cells, and is thought to play a large part in the overall regulation of gene expression in many organisms, giving them protection from viral infections and other undesirable elements.  Recent advances in gene silencing for basic research have lead to the concept of RNAi therapeutics against incurable diseases including hepatitis, cancer, viral infections and HIV by suppressing the expression of genes responsible for promoting these particular diseases.  Gene silencing takes place by degrading the mRNA required for protein synthesis.  In the absence of template mRNA, the cell is rendered incapable of producing proteins, thus suppressing expression and availability of the target protein.