RNA interference (RNAi) is the process by which the expression of a target gene can be effectively silenced or knocked down. RNA interference involves two types of small ribonucleic acid, namely, microRNA (miRNA) and small interfering RNA (siRNA), which can bind to specific messenger RNA (mRNA) molecules and increase or decrease their activity.
RNAi is a latest powerful geneknockdown technique that allows for tissue-specific, temporally controlled suppression of gene expression. Gene knockdown is achieved by causing the destruction of specific mRNA molecules by introducing small double-stranded interfering RNAs (dsRNA) into the cytoplasm. When siRNA is introduced into the cytoplasm of cells, it will be cut into short interfering RNAs (siRNAs) which can target specific mRNA and causing degradation of it. Therefore, the expression of a particular gene can be suppressed by introducing dsRNA whose antisense strand sequence matches the mRNA sequence. Gene knockdown by RNAi is temporary, but this can be solved by transfecting target tissues or cell lines so that they express dsRNA autonomously.
The versatility of the technique leads to a number of applications. RNAi can be used in drug or chemical target validation. RNAi can target specific spliced exons, enabling the investigation of the functional roles of alternatively spliced forms of a gene. RNAi is also valuable research tool in cell culture and in living organisms where it can be used for large-scale screens that systematically shut down each gene in the cell, thus helping to identify the components necessary for a particular cellular process or an event.