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RNA-induced silencing complex
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Diagram illustrating RNA interference, showing how both nuclear-encoded miRNA and synthetic double-stranded RNA are processed by enzymes like Dicer and RISC to cleave target mRNA, resulting in gene silencing.
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RNA-induced silencing complex

biochemistry
Also known as: RISC
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Quick Summary

Diagram illustrating RNA interference, showing how both nuclear-encoded miRNA and synthetic double-stranded RNA are processed by enzymes like Dicer and RISC to cleave target mRNA, resulting in gene silencing.
RNA interference RNA interference (RNAi) is a genetic regulatory system that functions to silence the activity of specific genes. RNAi occurs naturally, through the production of nuclear-encoded pre-microRNA (pre-miRNA), and can be induced experimentally, using short segments of synthetic double-stranded RNA (dsRNA). The synthetic dsRNA employed is typically either a small hairpin RNA (shRNA) or a short interfering RNA (siRNA). In both the natural and the experimental pathways, an enzyme known as DICER is necessary for the formation of miRNA from pre-miRNA or of siRNA from shRNA. The miRNA or siRNA then binds to an enzyme-containing molecule known as RNA-induced silencing complex (RISC). The miRNA-RISC or siRNA-RISC complex binds to target, or complementary, messengerRNA (mRNA) sequences, resulting in the enzymatic cleavage of the target mRNA. The cleaved mRNA is rendered nonfunctional and hence is “silenced.”

The RNA-induced silencing complex (RISC) is a crucial component of RNA interference (RNAi), a natural process in eukaryotic cells that regulates gene activity. RNAi functions by silencing, or deactivating, specific genes.1

This process begins with small RNA molecules, such as microRNAs (miRNAs) or short interfering RNAs (siRNAs), binding to the RISC. The RISC, which contains proteins including a ribonuclease enzyme, uses the bound small RNA to locate and bind to complementary messenger RNA (mRNA) sequences. Once bound, the RISC complex enzymatically cleaves the mRNA, preventing it from being translated into proteins and effectively silencing the gene.1

RNAi plays a role in cellular defense against viruses and in controlling transposons, or "jumping genes". It is also a powerful research tool used to study gene function and is being explored as a potential therapeutic strategy for various diseases.1

It is important to note that "RISC" can also refer to Reduced Instruction Set Computer, a type of microprocessor design, which is unrelated to the biochemical function of the RNA-induced silencing complex.2

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  1. RNA interference
  2. RNA interference
  3. RISC
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  5. RNAi

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