Small interfering RNA

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. They function by guiding the RNA-induced silencing complex (RISC) to complementary messenger RNA (mRNA) targets, leading to mRNA degradation or translational repression. This process is essential for maintaining cellular homeostasis and can influence the central dogma of molecular biology by effectively silencing specific genes and preventing their expression.

5 Must Know Facts For Your Next Test

1. siRNA is produced from longer double-stranded RNA precursors through the action of the Dicer enzyme, which cuts them into shorter fragments.
2. Once incorporated into RISC, siRNA pairs with complementary mRNA, leading to its degradation or blocking its translation into protein.
3. siRNA is not only important for gene regulation but also plays a crucial role in antiviral defense by targeting viral RNA.
4. The use of synthetic siRNA has become a powerful tool in research and therapeutic applications for silencing specific genes.
5. siRNA pathways are involved in epigenetic regulation as they can influence chromatin structure and gene expression patterns beyond just direct mRNA targeting.

Review Questions

• How does small interfering RNA participate in the RNA interference process and its impact on gene expression?
  • Small interfering RNA plays a vital role in the RNA interference process by guiding RISC to target specific mRNAs. Once bound to its complementary mRNA, siRNA leads to either degradation of the mRNA or inhibits its translation into protein. This mechanism effectively silences the expression of targeted genes, highlighting how siRNA contributes to the regulation of gene expression and cellular functions.
• Discuss the significance of Dicer in the biogenesis of small interfering RNAs and its overall influence on gene regulation.
  • Dicer is an essential enzyme that processes long double-stranded RNA into small interfering RNAs. By cutting these longer strands into 20-25 base pair fragments, Dicer facilitates the generation of functional siRNAs that can be loaded into RISC. This biogenesis step is critical because without Dicer's activity, the formation of siRNAs would be impaired, thus disrupting the RNA interference pathway and affecting gene regulation across various biological processes.
• Evaluate the broader implications of small interfering RNA technology in therapeutic applications and its potential to revolutionize gene therapy.
  • Small interfering RNA technology has significant implications for therapeutic applications, especially in gene therapy aimed at silencing disease-related genes. By designing synthetic siRNAs that specifically target pathological mRNAs, researchers can effectively reduce or eliminate harmful protein expressions associated with various diseases. This targeted approach not only allows for more precise treatments but also minimizes side effects compared to traditional methods, paving the way for innovative treatments in areas such as cancer, viral infections, and genetic disorders.

Related terms

RNA interference:

A biological process in which small RNA molecules, including siRNA, inhibit gene expression by targeting specific mRNA for degradation.

Dicer: An enzyme that processes long double-stranded RNA into short fragments of siRNA, which are then incorporated into the RISC.

mRNA:

Messenger RNA, a type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized.