How does RNA interference (RNAi) work in gene regulation?

RNA interference (RNAi) functions as a vital mechanism for regulating gene expression by specifically targeting messenger RNA (mRNA) molecules. The process begins when double-stranded RNA (dsRNA) is introduced into a cell, which is then processed into small interfering RNA (siRNA) or microRNA (miRNA) by the enzyme Dicer. These small RNA molecules are significant because they can bind to complementary mRNA sequences.

Once this binding occurs, the RNA-induced silencing complex (RISC) is activated. This complex uses the siRNA or miRNA as a guide to locate the corresponding mRNA. By binding to the mRNA, RISC induces various processes that lead to the degradation of the mRNA strand. Consequently, the mRNA is rendered non-functional, preventing it from being translated into a protein. This targeted degradation is a key component of gene regulation, allowing cells to fine-tune protein production in response to various needs, environmental conditions, or developmental signals.

This selective suppression of gene expression through the degradation of mRNA plays a crucial role in controlling biological processes such as development, defense against viral pathogens, and cellular responses to stress.