RNA interference

Definition

RNA interference (RNAi) is a biological process in which small RNA molecules, such as small interfering RNAs (siRNAs) and microRNAs (miRNAs), regulate gene expression by targeting messenger RNAs (mRNAs) for degradation or inhibiting their translation. This mechanism plays a crucial role in post-transcriptional regulation, allowing cells to fine-tune gene expression in response to various signals and conditions.

5 Must Know Facts For Your Next Test

1. RNA interference is a crucial cellular mechanism for regulating gene expression and maintaining cellular homeostasis.
2. The process of RNAi is initiated when double-stranded RNA is recognized and cleaved by Dicer into smaller siRNA or miRNA molecules.
3. Once processed, siRNAs or miRNAs are incorporated into RISC, where they guide the complex to complementary mRNA targets for silencing.
4. MicroRNAs can target multiple mRNAs simultaneously, allowing them to coordinate the expression of different genes in various biological processes.
5. RNAi has significant applications in research and therapeutic strategies, including gene knockdown studies and the development of RNAi-based treatments for diseases like cancer.

Review Questions

• How does RNA interference contribute to post-transcriptional regulation in cells?
  • RNA interference contributes to post-transcriptional regulation by utilizing small RNA molecules to control the levels of specific mRNAs within the cell. When small interfering RNAs (siRNAs) or microRNAs (miRNAs) bind to their complementary mRNA targets, they either promote degradation of the mRNA or inhibit its translation into proteins. This fine-tuning allows cells to respond dynamically to environmental changes and maintain proper gene expression without altering the DNA sequence.
• Discuss the roles of siRNAs and miRNAs in gene silencing mechanisms through RNA interference.
  • Both siRNAs and miRNAs play vital roles in gene silencing mechanisms through RNA interference. siRNAs are typically derived from long double-stranded RNA and function mainly by directly degrading their target mRNAs when bound to RISC. In contrast, miRNAs often arise from endogenous transcripts and can bind imperfectly to target mRNAs, resulting in translational repression rather than complete degradation. This duality enables a versatile regulation of gene expression across different biological contexts.
• Evaluate the impact of RNA interference on therapeutic applications and how it can be harnessed for treating diseases.
  • The impact of RNA interference on therapeutic applications is profound, as it provides a powerful tool for selectively silencing genes involved in various diseases. Researchers can design specific siRNAs or miRNAs that target overactive genes associated with cancer or genetic disorders, leading to potential treatments that are both effective and precise. Additionally, advancements in delivery methods for these small RNAs enable targeted therapies that minimize off-target effects, paving the way for innovative strategies to combat complex diseases at the molecular level.

Related terms

Small interfering RNA (siRNA): A type of double-stranded RNA molecule that is involved in the RNAi process, typically 20-25 nucleotides long, and plays a key role in the degradation of target mRNAs.

MicroRNA (miRNA): A class of small non-coding RNA molecules, usually about 22 nucleotides long, that regulate gene expression by binding to complementary sequences on target mRNAs, leading to translational repression or degradation.

Dicer:

An enzyme that processes long double-stranded RNA into short fragments, such as siRNAs and miRNAs, which are then incorporated into the RNA-induced silencing complex (RISC) to mediate gene silencing.