MicroRNAs

Definition

MicroRNAs (miRNAs) are small, non-coding RNA molecules, typically 20-24 nucleotides long, that play a crucial role in regulating gene expression at the post-transcriptional level. They bind to complementary sequences on messenger RNA (mRNA) molecules, leading to mRNA degradation or inhibition of translation, thereby fine-tuning protein production and influencing various biological processes such as development, differentiation, and response to stress.

5 Must Know Facts For Your Next Test

1. MicroRNAs are derived from larger primary transcripts called pri-miRNAs, which undergo processing by the Dicer enzyme to produce mature miRNA strands.
2. Each microRNA can target multiple mRNAs, making them key players in complex regulatory networks that control gene expression.
3. Dysregulation of microRNAs has been implicated in various diseases, including cancer, cardiovascular disorders, and neurological diseases.
4. MicroRNAs are involved in essential processes such as cell proliferation, apoptosis, and immune response, highlighting their importance in maintaining cellular homeostasis.
5. The study of microRNAs has led to potential therapeutic approaches, including using miRNA mimics or inhibitors to regulate gene expression in disease contexts.

Review Questions

• How do microRNAs contribute to the regulation of gene expression at the post-transcriptional level?
  • MicroRNAs regulate gene expression by binding to complementary sequences on target mRNAs. This interaction can lead to either degradation of the mRNA or inhibition of its translation into protein. By modulating the stability and translation of mRNAs, microRNAs play a pivotal role in controlling protein levels within the cell, influencing various biological processes such as development and stress responses.
• Discuss the mechanisms through which Dicer processes precursor microRNAs into functional microRNAs.
  • Dicer is an enzyme that processes long double-stranded RNA and precursor microRNA (pri-miRNA) into shorter fragments known as mature microRNAs. The pri-miRNA is first cleaved into a hairpin structure called pre-miRNA. Dicer then further cleaves this pre-miRNA into a double-stranded RNA molecule of about 20-24 nucleotides. One strand is incorporated into the RNA-induced silencing complex (RISC), while the other strand is typically degraded. This processing is crucial for producing functional microRNAs that can regulate gene expression.
• Evaluate the potential implications of microRNA dysregulation in human diseases and how this knowledge could inform therapeutic strategies.
  • Dysregulation of microRNAs has significant implications for human diseases, particularly in conditions like cancer and cardiovascular disorders where miRNAs may either promote or suppress tumor formation. Understanding the specific roles that various microRNAs play in these diseases allows researchers to consider innovative therapeutic strategies such as developing miRNA mimics to restore normal function or inhibitors to block aberrant pathways. This targeted approach represents a promising avenue for treating diseases at the molecular level by correcting gene expression patterns disrupted by dysregulated microRNAs.

Related terms

RNA interference: A biological process where RNA molecules inhibit gene expression or translation by targeting specific mRNA for degradation or preventing its translation.

Dicer: An enzyme that processes long double-stranded RNA and precursor microRNA into shorter active fragments, which are then incorporated into the RNA-induced silencing complex (RISC).

Argonaute: A family of proteins that are essential components of the RNA-induced silencing complex (RISC), responsible for guiding microRNAs to their target mRNAs and facilitating gene silencing.