MiRNA

Definition

miRNA, or microRNA, is a small non-coding RNA molecule, typically 20 to 22 nucleotides long, that plays a crucial role in the regulation of gene expression by targeting messenger RNA (mRNA) for degradation or inhibiting its translation. These molecules are key players in post-transcriptional regulation, influencing various biological processes such as development, differentiation, and cellular responses to stress.

5 Must Know Facts For Your Next Test

1. miRNAs are generated from longer primary transcripts called pri-miRNAs, which are processed by the Drosha enzyme into precursor miRNAs (pre-miRNAs) before being exported to the cytoplasm.
2. In the cytoplasm, pre-miRNAs are further processed by the Dicer enzyme into mature miRNAs that can then engage with the RNA-induced silencing complex (RISC).
3. The binding of miRNAs to complementary sequences on mRNAs leads to either degradation of the mRNA or repression of its translation into protein.
4. miRNAs are involved in regulating numerous cellular processes, including cell proliferation, apoptosis, and stress responses, making them important for maintaining cellular homeostasis.
5. Dysregulation of miRNA expression has been linked to various diseases, including cancer, cardiovascular diseases, and neurological disorders, highlighting their potential as therapeutic targets.

Review Questions

• How do miRNAs influence gene expression at the post-transcriptional level?
  • miRNAs influence gene expression post-transcriptionally by binding to complementary sequences on mRNAs. This binding can lead to two main outcomes: degradation of the target mRNA or inhibition of its translation into protein. By regulating the stability and translational efficiency of mRNAs, miRNAs play a vital role in fine-tuning gene expression and maintaining cellular functions.
• Discuss the importance of miRNAs in cellular processes and their potential implications in disease.
  • miRNAs are crucial for various cellular processes such as development, differentiation, and response to environmental stress. They modulate gene expression patterns necessary for these processes by targeting specific mRNAs. The dysregulation of miRNA levels has been associated with several diseases, particularly cancer and cardiovascular conditions, indicating their importance as biomarkers and potential therapeutic targets in these pathologies.
• Evaluate how understanding miRNA function can advance therapeutic strategies in treating diseases.
  • Understanding miRNA function can significantly advance therapeutic strategies by enabling the development of miRNA-based therapies. For instance, restoring the expression of tumor-suppressive miRNAs or inhibiting oncogenic miRNAs could provide novel approaches to cancer treatment. Additionally, since miRNAs are involved in various cellular pathways and diseases, designing drugs that modulate miRNA activity may offer new opportunities for treating a range of conditions, thus underscoring their potential as powerful tools in precision medicine.

Related terms

mRNA:

Messenger RNA (mRNA) is a type of RNA that carries genetic information from DNA to the ribosome, where it serves as a template for protein synthesis.

RNA interference (RNAi): RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression by destroying specific mRNA molecules, effectively silencing genes.

Transcription factors:

Transcription factors are proteins that help regulate the transcription of specific genes by binding to nearby DNA.