SiRNA

Definition

Small interfering RNA (siRNA) is a class of double-stranded RNA molecules, typically 20-25 base pairs in length, that play a crucial role in the RNA interference (RNAi) pathway. siRNA functions by targeting specific mRNA molecules for degradation, thus preventing the translation of genes into proteins and regulating gene expression at a post-transcriptional level.

5 Must Know Facts For Your Next Test

1. siRNAs are often used in laboratory research to silence specific genes, allowing scientists to study gene function and the effects of gene knockdown on cellular processes.
2. The mechanism of action for siRNA involves its incorporation into the RISC, where it guides the complex to complementary mRNA strands, leading to their cleavage and degradation.
3. siRNAs can be introduced into cells through various methods such as transfection, electroporation, or viral delivery systems for therapeutic applications.
4. In addition to basic research, siRNAs have potential therapeutic uses in treating diseases caused by overexpression of harmful genes, such as certain cancers and viral infections.
5. The stability and specificity of siRNAs make them a powerful tool for gene silencing; however, off-target effects remain a concern in their application for therapeutic purposes.

Review Questions

• How does siRNA contribute to gene regulation within the cell?
  • siRNA contributes to gene regulation by targeting specific mRNA molecules for degradation. When siRNA is incorporated into the RNA-induced silencing complex (RISC), it guides the complex to complementary mRNA sequences. This binding leads to the cleavage of the mRNA, preventing its translation into protein and thus effectively silencing the targeted gene.
• Discuss the differences between siRNA and miRNA in terms of their structure and function in gene regulation.
  • While both siRNA and miRNA are small RNA molecules involved in gene regulation, they differ in structure and function. siRNAs are typically derived from long double-stranded RNA and are perfectly complementary to their target mRNAs, leading to direct degradation. In contrast, miRNAs are usually produced from single-stranded precursors and may have imperfect base pairing with their targets, resulting in translational repression rather than direct cleavage. This distinction affects how each type regulates gene expression.
• Evaluate the potential applications of siRNA in therapeutic contexts and discuss the challenges associated with its use.
  • siRNA has significant potential in therapeutics, particularly for diseases where specific genes contribute to pathology, such as certain cancers and viral infections. By silencing these overactive genes, siRNAs could provide targeted treatment options. However, challenges such as off-target effects, delivery mechanisms to ensure effective cellular uptake, and the stability of siRNAs in biological systems must be addressed to fully realize their therapeutic potential.

Related terms

miRNA: MicroRNA (miRNA) is a class of small RNA molecules, similar to siRNA, that also regulate gene expression by binding to complementary sequences on mRNA and inhibiting their translation.

RNAi: RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression or translation, typically through the action of siRNA and miRNA.

Dicer: Dicer is an enzyme that processes long double-stranded RNA into smaller fragments, including siRNAs, which are then incorporated into the RNA-induced silencing complex (RISC).