Microrna (mirna)

Definition

Microrna (miRNA) is a small, non-coding RNA molecule, typically about 20-24 nucleotides in length, that plays a crucial role in regulating gene expression at the post-transcriptional level. These molecules bind to complementary sequences in target messenger RNAs (mRNAs), leading to mRNA degradation or inhibition of translation. By modulating the stability and translation of specific mRNAs, miRNAs are essential for various cellular processes, including development, differentiation, and response to environmental stimuli.

5 Must Know Facts For Your Next Test

1. miRNAs are derived from longer primary transcripts known as primary miRNAs (pri-miRNAs), which undergo processing by enzymes like Drosha and Dicer to form the mature miRNA.
2. Each miRNA can potentially regulate hundreds of target mRNAs, allowing for widespread influence on gene expression networks.
3. miRNAs are involved in various biological processes, such as cell proliferation, apoptosis, differentiation, and immune responses.
4. The dysregulation of miRNA expression has been linked to several diseases, including cancer, cardiovascular diseases, and neurodegenerative disorders.
5. miRNAs can also function as oncogenes or tumor suppressors depending on their targets and the context in which they are expressed.

Review Questions

• How do micrornas influence gene expression at the post-transcriptional level?
  • Micrornas influence gene expression by binding to complementary sequences in target mRNAs. This binding can lead to two primary outcomes: either degradation of the mRNA or inhibition of its translation into protein. Through these mechanisms, miRNAs can finely tune gene expression in response to various cellular signals and conditions, impacting essential processes such as cell growth and differentiation.
• Discuss the role of miRNAs in cellular processes and how their dysregulation can lead to disease.
  • miRNAs play critical roles in regulating various cellular processes like proliferation, differentiation, and apoptosis by modulating the expression levels of target genes. When miRNA expression is dysregulated, it can disrupt normal cellular functions and contribute to disease development. For instance, overexpression of certain miRNAs may promote cancer cell proliferation by downregulating tumor suppressor genes, while loss of specific miRNAs can result in decreased apoptosis and resistance to cell death.
• Evaluate the potential therapeutic implications of targeting micrornas in disease treatment.
  • Targeting micrornas presents a promising therapeutic strategy for treating various diseases, especially cancers where miRNA dysregulation is common. By designing inhibitors or mimics that can either suppress or enhance specific miRNA activity, researchers aim to restore normal gene expression patterns. This approach could lead to more effective treatments with fewer side effects compared to traditional therapies, as it allows for precise modulation of multiple pathways simultaneously.

Related terms

messenger RNA (mRNA): A type of RNA that conveys genetic information from DNA to the ribosome, where it serves as a template for protein synthesis.

RNA interference (RNAi): A biological process in which small RNA molecules, including miRNAs and siRNAs, inhibit gene expression by targeting mRNA for degradation.

post-transcriptional regulation: The control of gene expression at the RNA level, which includes processes such as splicing, editing, transport, and degradation of RNA molecules.