How do miRNAs function in post-transcriptional gene regulation?

miRNAs bind to target mRNA molecules and inhibit their translation or promote their degradation.

miRNAs, or microRNAs, are small non-coding RNA molecules that play a crucial role in post-transcriptional gene regulation. They are transcribed from DNA and processed in the nucleus before being exported to the cytoplasm. Once in the cytoplasm, miRNAs bind to target mRNA molecules through base pairing interactions. This binding can lead to either inhibition of translation or degradation of the mRNA.

Inhibition of translation occurs when miRNAs bind to the 3' untranslated region (UTR) of target mRNA molecules. This binding can prevent the ribosome from binding to the mRNA, thus inhibiting translation. Alternatively, miRNAs can promote degradation of target mRNA molecules by binding to the coding region or the 5' UTR. This binding can lead to recruitment of RNA-induced silencing complexes (RISCs), which can cleave the mRNA or promote its degradation.

miRNAs play a crucial role in many biological processes, including development, differentiation, and disease. Dysregulation of miRNA expression has been implicated in a variety of diseases, including cancer, cardiovascular disease, and neurological disorders. Understanding the mechanisms by which miRNAs function in post-transcriptional gene regulation is therefore of great importance for both basic research and clinical applications.