CONCEPT OF RNA SILENCING AND APPLICATIONS OF SIRNA IN HEALTHCARE

Royani Saha
Page No. 54-62

After the Human Genome Project (HGP), scientists are able to decode the genetic roots of diseases such as cancer and rheumatoid arthritis; using new generation gene-sequencing technology. Now it is possible to reach the potential root of genetic diseases and gain more insight about the genetic component of the disease and its underlying causes. By using this information, it is possible to devise drugs which have the potential to act on these underlying disease causing genes; it paved the way for discovery of new technologies based on RNA and its potential versatile forms. RNA based therapeutics are categorized according to their mechanism of action, which involves and catalytically active molecules that bind to other proteins RNAi (RNA interference) and mRNA translation inhibitors (antisense). Researchers are working on developing vaccines that use RNA encoded proteins from pathogens such as influenza, rabies, or Zika virus. The new mRNA will translate the sequenced strands into protein, stimulating the immune system to produce a specific immune response to the exact strain of the pathogen. RNAi was the Nobel Prize-winning discovery in 2006, opening the door to a plethora of new and exciting therapies. The discovery of Mello and colleagues, which states the potential use of dsRNA (double stranded RNA) in degradation of target mRNA sequences in C.elegans and mammalian cells, has brought RNAi into the spotlight.  RNA silencing can be mediated by siRNA (small interfering RNA) or miRNA (micro RNA); they are handled by the cellular enzyme Dicer for processing before being integrated into the RISC (RNA-induced silencing complex complex). The primary distinction between miRNA and siRNA is that miRNA can act on multiple mRNA targets whereas siRNA can only act on one mRNA target, which is very specific in targeting a mRNA molecule where the gene expression is to be silenced.
Key words: RNA Silencing, Gene knockdown, RNA interference, RNAi therapeutics, siRNA, RISC, dsRNA, miRNA, mRNA molecule target, RNA splicing.