MicroRNAs

Definition

MicroRNAs are small, non-coding RNA molecules, typically around 21-23 nucleotides long, that play a crucial role in regulating gene expression. They function by binding to complementary sequences in messenger RNA (mRNA), leading to mRNA degradation or inhibition of translation, thereby influencing various biological processes. These tiny molecules are key players in the regulation of gene expression and are deeply intertwined with mechanisms like DNA methylation and other epigenetic modifications that impact cellular behavior and phenotype.

5 Must Know Facts For Your Next Test

1. MicroRNAs are involved in regulating a wide range of biological processes, including development, cell differentiation, proliferation, and apoptosis.
2. The biogenesis of microRNAs involves transcription from DNA into primary microRNA (pri-miRNA), which is then processed into precursor microRNA (pre-miRNA) and ultimately matured into functional microRNA.
3. MicroRNAs can act as oncogenes or tumor suppressors, depending on their target mRNAs and the context of their expression in cells, linking them to cancer biology.
4. The interaction between microRNAs and mRNA can lead to either degradation of the mRNA or repression of its translation, making them critical regulators of gene expression.
5. Alterations in the expression levels of specific microRNAs can be associated with various diseases, including cardiovascular diseases, neurological disorders, and cancers.

Review Questions

• How do microRNAs contribute to gene regulation at the post-transcriptional level?
  • MicroRNAs contribute to gene regulation by binding to complementary sequences on messenger RNAs (mRNAs), which can lead to either degradation of the mRNA or repression of its translation. This interaction allows microRNAs to finely tune gene expression in response to cellular conditions and external signals. By modulating the stability and translation efficiency of mRNAs, microRNAs play a crucial role in various biological processes such as development and response to stress.
• Discuss the relationship between microRNAs and epigenetic marks such as DNA methylation.
  • MicroRNAs and epigenetic marks like DNA methylation are interconnected in regulating gene expression. DNA methylation can influence the transcription of genes that encode microRNAs, thereby affecting their levels and function. In turn, microRNAs can target genes involved in the establishment or maintenance of epigenetic modifications, creating a feedback loop that shapes cellular behavior. This interplay is essential for processes like differentiation and development, where precise control over gene expression is critical.
• Evaluate the implications of altered microRNA expression on human health and disease.
  • Altered microRNA expression has significant implications for human health as it can disrupt normal regulatory networks governing cell function. For instance, specific microRNAs may act as oncogenes when overexpressed or as tumor suppressors when downregulated, influencing cancer progression. Additionally, changes in microRNA profiles have been linked to various diseases such as cardiovascular conditions and neurodegenerative disorders. Understanding these alterations can provide insights into disease mechanisms and potential therapeutic targets for treatment.

Related terms

Gene Silencing: A process by which the expression of a gene is prevented or reduced, often mediated by mechanisms such as microRNAs or RNA interference.

Epigenetics: The study of heritable changes in gene function that do not involve changes to the underlying DNA sequence, often influenced by environmental factors and involving modifications like DNA methylation.

Messenger RNA (mRNA): A type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized; it is a key target for regulation by microRNAs.