SiRNA

Definition

Small interfering RNA (siRNA) is a class of double-stranded RNA molecules, typically 20-25 base pairs in length, that play a critical role in the regulation of gene expression through a process known as RNA interference (RNAi). siRNAs are key players in the cellular defense against viral infections and transposons, as well as in the regulation of endogenous genes. They function by binding to complementary mRNA sequences, leading to mRNA degradation and silencing of gene expression.

5 Must Know Facts For Your Next Test

1. siRNA is produced from longer double-stranded RNA molecules through the action of the Dicer enzyme, which cleaves the RNA into shorter fragments.
2. Once formed, siRNAs are incorporated into the RNA-induced silencing complex (RISC), where they guide Argonaute proteins to target complementary mRNA sequences for degradation.
3. The specificity of siRNA for its target mRNA allows for precise regulation of gene expression, making it a valuable tool in research and therapeutic applications.
4. siRNAs can be delivered into cells through various methods, including transfection and viral vectors, allowing for potential applications in gene therapy.
5. The discovery of siRNA has opened up new avenues for studying gene function and has led to the development of RNAi-based therapies for diseases such as cancer and viral infections.

Review Questions

• How does siRNA contribute to the process of RNA interference and what is its mechanism of action?
  • siRNA contributes to RNA interference by specifically binding to complementary mRNA sequences. Once bound, it triggers the degradation of the mRNA, preventing its translation into protein. This process is facilitated by the RNA-induced silencing complex (RISC), which includes Argonaute proteins that carry out the cleavage of the target mRNA. This precise targeting allows siRNAs to effectively silence gene expression.
• Discuss the role of Dicer in the biogenesis of siRNA and its importance in cellular functions.
  • Dicer plays a crucial role in generating siRNA from long double-stranded RNA precursors. By cleaving these longer strands into shorter segments, Dicer facilitates the production of functional siRNAs that are essential for RNA interference. The ability of Dicer to process different types of RNA molecules ensures that cells can effectively respond to various challenges, including viral infections and transposon activity, by regulating gene expression accurately.
• Evaluate the potential therapeutic applications of siRNA technology and its impact on modern medicine.
  • siRNA technology holds significant promise for therapeutic applications, particularly in treating diseases such as cancer and viral infections. By targeting specific mRNA transcripts for degradation, siRNAs can silence genes that contribute to disease progression or virulence. This targeted approach minimizes off-target effects and enhances treatment efficacy. The advent of siRNA-based therapies represents a revolutionary step in modern medicine, offering new strategies for managing previously untreatable conditions and advancing personalized medicine.

Related terms

RNA Interference: A biological process where RNA molecules inhibit gene expression or translation by neutralizing targeted mRNA molecules.

Dicer: An enzyme that processes long double-stranded RNA and precursor microRNAs into short fragments of RNA, including siRNAs.

Argonaute: A family of proteins that play a crucial role in the RNAi pathway by forming complexes with siRNAs and guiding them to their target mRNA.