SiRNASmall interfering RNA (siRNA) or silencing RNA is used in the gene silencing technique to suppress gene expression. siRNAs naturally occur in cells as a component of the post-transcriptional gene silencing (PTGS) apparatus. Soon after discoveryof siRNA in plant cells, scientists began using siRNAs in vitro to study gene expression. Performing RNAi in invertebrates is reasonably easy because a simple transfection of long a dsRNA is enough to degrade the target mRNA. Vertebrate cells elicit a significant antiviral response when they detect the presence of a long dsRNA. Consequently, instead of knocking down the identified gene, the cell goes through apoptosis giving entirely undesirable results. Scientists havesolved the problem of antiviral response by utilizing small-sized siRNA. They are created by segmenting a long dsRNA. When generated appropriately synthetic siRNA are potent gene silencers, do not produce any significant antiviral response and exhibit remarkable specificity to the target mRNA. esearchers develop siRNA from long dsRNA by dicing small hairpin RNAs or long dsRNA sequences, which in effectis an RNase III family endoribonuclease enzyme . The dicer cuts a dsRNA into smaller siRNA segments that usuallyends with two base overhang . siRNAs are often introduced in cell lines either through transfection or electroporation. Soon after being inserted in the host cell, siRNA molecules become a part of the RNA-induced silencing complex (RISC). Guided by the antisense strand of the siRNA, RISC degrades the targeted mRNA inhibiting its translation. The success of RNAi is dependant on correct delivery of siRNA in appropriate amount at a time when it will brings about the maximum expected response. Such precisioncan be tricky. Off-targeting by siRNAs proves lethal and poses analytical issues at times. Researchers are looking for better ways of designing and delivering siRNA. The excellent response of siRNAs has impelled many organizations to market gene specific pre-designed kits to help researchers. About 3-5 siRNAsper gene are needed to have a potent RNAi effect . The consequent dollar intensive nature of this technology dissuades many laboratories from exploiting its true potential. Efforts are on to develop innovative yet reasonably affordable in vitro generation of siRNAs. siRNA helps scientists to knockdown expressions of a target gene. This is done to have a superior understanding about the functions of the knocked down genes. They help understand the complex pathways genes that eventually will help develop effective treatments for many lethal diseases including cancer, autoimmune discrepancy, viral infections, Huntington disease and degenerative conditions. Without doubt, laboratory application of siRNA for its therapeutic uses is lately gaining popularity. |
