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How do microRNAs regulate gene expression?
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Nucleic acid
A portion of the polynucleotide chain of deoxyribonucleic acid (DNA), with an inset showing the corresponding pentose sugar and pyrimidine base in ribonucleic acid (RNA).
MicroRNAs (miRNAs) regulate gene expression posttranscriptionally by silencing protein synthesis. These small, noncoding RNA molecules, typically 21β25 nucleotides in length, originate from double-stranded precursors that are processed into mature, single-stranded forms.12
The regulation process occurs through the following mechanism:
- Binding: Mature miRNAs attach to complementary sequences on messenger RNA (mRNA) molecules.12
- Complex Formation: In many instances, the miRNA binds to an RNA-induced silencing complex (RISC), which directs the complex to the target mRNA.2
- Silencing: Once bound, the miRNA prevents protein synthesis by causing either the enzymatic degradation of the mRNA or translational repression, where the mRNA is inhibited from being translated into a protein without being degraded.12
By fine-tuning gene expression, miRNAs ensure that specific genes are expressed at the appropriate time and in the correct amounts, which is essential for processes like cell differentiation, growth, and development. Aberrant miRNA activity is linked to various diseases, including cancer and autoimmune disorders, as they can influence key genes involved in cell proliferation.1