An Introduction to siRNA - The Gene Silencing Ninja!

This video describes the concept and mechanism of small interfering RNA, or siRNA and it's uses in the research environment. Small interfering RNA is an anti-viral defense mechanism employed in the cell. It operates to prevent the incorporation of viral RNA into the cell's genetic material. siRNA acts as a "genome ninja" and locates, and cuts double stranded RNA, before it can cause any harm in the cell. Molecular biologists have been able to exploit this process in order to produce gene silencing effects in the laboratory. Gene silencing via siRNA has massive potential in the gene therapy industry, as well as research purposes. As we know, the central dogma of protein synthesis follows three sequential steps, beginning with DNA transcribed into mRNA, which is then translated into protein. In order to silence a gene, one may target the DNA-RNA step, or the RNA-protein stage of this process. Silencing of the transcription involves influencing the DNA of the organism via genetic engineering. This is unfavourable in many applications, as changing the genome may carry ethical complications. Therefore, many choose to use RNA interference through siRNA as a means of gene silencing. Here we have a cell that is producing a protein. We want to prevent this protein being produced through silencing the gene. We do this by interfering with the RNA before it is able to be translated into the protein. To do this, a double strand of RNA complementary to the target mRNA is produced in the lab. This double stranded RNA is then inserted into the cell, where the cell then recognises it as foreign. Lets zoom into the cell and see what happens! When the double strand of RNA enters the cell, the anti-viral enzyme known as the DICER cuts the RNA into smaller pieces, the DICER enzyme then complexes with the small strand of RNA and recruits other proteins to form the RNA Induced Silencing Complex, otherwise known as RISC. The dicer enzyme is later used in the pathway to cut the target mRNA. The RNA Induced Silencing Complex then splits the RNA into two single strands, known as the sense and anti-sense strands. The sense strand is discarded and the RISC complex holds onto the anti-sense strand, in order to use it to find its complementary sequence. In this case, the mRNA of the gene that we wish to silence. When the transcribed mRNA leaves the nucleus to be translated into protein, the RISC complex locates the complementary sequence and associates with the mRNA via complementary base pairing. RISC then cleaves the mRNA strand. The cleaved mRNA is then rapidly degraded in the cell, before it has even had the chance to make the protein. This process essentially silences the gene - all without even touching the DNA! This video was brought to you by three fourth year students at Dundalk IT: Clare, Leanne and Ciarán.

Channel: Ciarán Murphy

Views: 46,946

Keywords: siRNA, small interfering RNA, antisense technology, gene silencing, knockdown, knockout, RNA interference, RNA induced silencing complex, DICER, endonuclease, genetic engineering, genetically modified organisms, hybridisation arrest, dsRNA, viral defence, RNAi, Dundalk Institute of Technology, Biopharmaceutical Science, DkIT, Dundalk, Upstream Processing, Transcription, Translation Arrest, RNA degradation, coronavirus, COVID-19, Coronavirus research, Coronavirus treatment

Id: X9vzczGEMMo

Length: 4min 16sec (256 seconds)

Published: Thu Nov 23 2017