SiRNA

siRNA

Small interfering RNA (siRNA), sometimes known as short interfering RNA or silencing RNA, is a class of double-stranded RNA molecules, 20-25 base pairs in length. siRNA is similar to miRNA, and operates within the RNA interference (RNAi) pathway, where it interferes with the expression of specific genes with complementary nucleotide sequences by degrading mRNA after transcription, preventing translation.

Discovery

RNA interference (RNAi) was known to be a natural mechanism for sequence-specific gene silencing in plants, fungi, and animals. The discovery of siRNA came from research into RNAi. In 1998, Andrew Fire and Craig Mello showed that when C. elegans was exposed to double-stranded RNA, it effectively silenced the corresponding gene. This discovery won them the 2006 Nobel Prize in Physiology or Medicine.

Mechanism of action

siRNA works by causing a RNA-induced silencing complex (RISC) to form. The siRNA is unwound, and one strand (the guide strand) is loaded into the RISC. The guide strand then base pairs with its complementary sequence in the mRNA. Once bound, the RISC uses an endonuclease to cleave the mRNA, thereby preventing it from being used as a translation template.

Applications

siRNA has potential applications in gene therapy, functional genomics, and in the treatment of viral infections, cancers, and genetic disorders. It is also used in research to knock down genes to study their function.

See also

• RNA interference
• MicroRNA
• Gene silencing
• Gene therapy

References

SiRNA Resources
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