RNA has a critical role in gene silencing, especially through RNA interference (RNAi), a cellular process that monitors gene expression. Small RNA, including microRNAs (miRNAs) and small interfering RNAs (siRNAs), directs protein complexes to the target messenger RNAs (mRNAs) to degrade or inhibit their translation, halting protein synthesis. This process keeps cellular activities such as development, immune response, and stress response in check.
In RNAi, siRNAs are derived from double-stranded RNA and direct the RNA-induced silencing complex (RISC) to cleave complementary mRNA, whereas miRNAs bind partially complementary sequences to silence translation. Another important pathway is through long non-coding RNAs (lncRNAs), which regulate gene expression at transcriptional and post-transcriptional levels. RNA-mediated gene silencing plays a crucial role in genetic regulation, antiviral defense, and potential therapeutic use, including targeting disease-causing genes. Accordingly, RNA serves as a central regulator in cellular activity, controlling many physiological and pathological processes.