Summary
Small interfering RNAs guide the RISC complex to degrade matching mRNA and silence genes.
In depth
Long double-stranded RNA is cut by Dicer into 21 to 23 nt siRNAs that load into RISC; the guide strand pairs with target mRNA and Argonaute cleaves it. Fire and Mello showed it in C. elegans (Nobel 2006).
It protects against viruses and transposons, and is used experimentally to knock down genes.
RNAi evolved as a defence against viruses and transposons and as a way to tune gene expression. The guide strand of siRNA is chosen by the thermodynamic stability of the ends of the duplex. In plants and worms the signal can spread between cells and amplify through RNA-dependent polymerases; in humans, amplification is limited.
Therapeutic siRNAs such as patisiran (for hereditary transthyretin amyloidosis, approved 2018) are delivered in lipid particles, and others conjugated to sugar groups reach the liver. In research, RNAi screens switched off genes one by one to find their roles.
Frequently asked questions
What is RNA Interference?
Small interfering RNAs guide the RISC complex to degrade matching mRNA and silence genes.
Which area of biology covers RNA Interference, and how advanced is it?
RNA Interference is one of the 52 topics in Molecular Biology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include microRNA, CRISPR-Cas9 Mechanism, Ubiquitin-Proteasome System.
Why does RNA Interference matter?
The discovery was awarded the 2006 Nobel Prize and gave a way to silence disease genes.
Can you give an example of RNA Interference?
The drug patisiran is an siRNA treating hereditary transthyretin amyloidosis.
What should I learn before RNA Interference?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to RNA Interference. Advanced topics assume the Intermediate vocabulary.
What topics are related to RNA Interference?
The closest topics to RNA Interference are microRNA, CRISPR-Cas9 Mechanism, Ubiquitin-Proteasome System, Lac Operon. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand RNA Interference?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for RNA Interference. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is RNA Interference different from microRNA?
RNA Interference: Small interfering RNAs guide the RISC complex to degrade matching mRNA and silence genes. microRNA: About 22-nucleotide RNAs that fine-tune gene expression by blocking translation or promoting mRNA decay. Read both side by side and note what each one explains.
How should I study RNA Interference step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with microRNA and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.