MicroRNAs (miRNAs) are small, non-coding RNA molecules, usually about 20–24 nucleotides long, that regulate gene expression after transcription. They do not make proteins themselves. Instead, they control how much protein a gene produces by acting on messenger RNA (mRNA). The 2024 Nobel Prize in Physiology or Medicine highlighted their importance in development, disease and modern biotechnology.
MicroRNAs work mainly through post-transcriptional gene regulation. In simple terms, they decide whether a message copied from DNA should be translated into protein or silenced.
Main mechanisms of microRNAs
- Formation of miRNA: First, miRNA genes are transcribed into primary miRNA. Then, enzymes such as Drosha and Dicer process them into mature miRNAs.
- Binding with mRNA: Mature miRNA joins a protein complex called RISC or RNA-induced silencing complex. This complex guides the miRNA towards a target mRNA.
- Gene silencing: If the miRNA matches the target mRNA, it can block protein production. Therefore, the gene remains present, but its expression reduces.
- mRNA degradation: In some cases, miRNA causes the target mRNA to break down. As a result, the cell cannot translate that mRNA into protein.
- Fine-tuning of gene expression: One miRNA can regulate many genes, and one gene can be regulated by many miRNAs. Hence, miRNAs act like molecular “dimmer switches” of the cell.
Therapeutic potentials of miRNAs
MicroRNAs have wide therapeutic potential because abnormal miRNA activity is linked with several diseases.
- Cancer treatment: Some miRNAs act as tumour suppressors, while others promote cancer. Therefore, miRNA-based therapy can help block cancer growth or restore normal gene control.
- Cardiovascular diseases: miRNAs regulate heart development, blood vessel function and cardiac repair. They may help in treating heart failure and atherosclerosis.
- Viral infections: miRNAs can influence viral replication and immune response. Hence, they may become useful in antiviral therapies.
- Genetic and neurological disorders: Since miRNAs control gene networks, they may help in treating diseases linked to abnormal gene expression.
- Biomarkers: miRNAs remain stable in blood and other body fluids. Therefore, doctors may use them for early diagnosis, disease monitoring and personalised medicine.
However, challenges remain. Scientists must improve safe delivery, target specificity, dosage control and avoid off-target effects before miRNA therapies become widely successful.
Nobel Prize 2024
The 2024 Nobel Prize in Physiology or Medicine was awarded jointly to Victor Ambros and Gary Ruvkun for the discovery of microRNA and its role in post-transcriptional gene regulation. Their work began with studies on the tiny worm C. elegans and later showed a fundamental mechanism of gene regulation in multicellular organisms.
Conclusion
Thus, microRNAs are small molecules with a major biological role. They regulate gene expression, guide development, maintain cellular balance and influence disease pathways. Their discovery has opened new possibilities in diagnostics, cancer therapy, precision medicine and biotechnology. Therefore, miRNAs represent a powerful bridge between basic biology and future medicine.
