Why in the news?

Nobel Prize in Physiology or Medicine 2024 has been awarded to Victor Ambros and Gary Ruvkun for the discovery of microRNA and its role in post-transcriptional Gene Regulation.

About the Discovery 

• In 1993, Victor Ambros and Gary Ruvkun discovered microRNA and its role in gene regulation after transcription.
  • Till 1993, it was believed that gene regulation is limited to specialised proteins called transcription factors, which bind to specific regions in Deoxyribonucleic acid (DNA) and determine which messenger Ribonucleic acid (RNA) (mRNA) are produced.
  • However, it was discovered that regulation by microRNAs occurs at a later stage in the process of gene expression, post-transcription. 
• They discovered role of microRNA by investigating mutant Caenorhabditis Elegans nematodes with developmental defects caused by alterations at two positions in their gene.
• Discovery revealed a completely new principle of gene regulation that turned out to be essential for multicellular organisms, including humans.

About microRNA (miRNA)

• It is a small non-coding RNA (single-stranded molecules playing key role in turning DNA instructions into proteins) that helps cells regulate gene expression.   
• It controls gene expression by binding with mRNA and preventing them from being translated into proteins or by degrading/destroying mRNA altogether. 
  • Proteins in the nucleus regulate RNA transcription and splicing while microRNAs control the translation and degradation of mRNA in the cytoplasm.
• There are more than a thousand genes for different microRNAs in humans, and gene regulation by microRNA is universal among multicellular organisms.

About Gene Regulation 

• Gene regulation is the process used to control the timing, location and amount in which genes (out of many genes in a genome) are expressed. 
  • Genetic information flows from DNA to mRNA, via a process called transcription, and then on to the cellular machinery for protein production. 
• It is important for an organism to respond to environmental changes.
• Gene Expression: 
  • Human organs and tissues consist of different cell types, the chromosomes in the cell contain the same set of genes with the same set of instructions.
  • However, due to gene regulation, these different cells (like muscle cells, nerve cells etc.) express unique sets of proteins, enabling them to perform their specialized functions. 

Significance/Application of the Discovery 

Discovery of microRNA helps in understanding different aspects related with gene regulation and role played by it different process such as:

• Cellular Development: miRNAs are involved in the self-renewal and differentiation of stem cells and development of tissues and organs.
• Immune Response: miRNAs regulate innate and adaptive immune responses. 
• Oncogenesis: Abnormal regulation by microRNA can contribute to cancer, and mutations in genes causing conditions such as congenital hearing loss, eye and skeletal disorders.
• Disease diagnostics: Used as biomarkers for human cancer diagnosis, prognosis, and therapeutic targets.

About Ribonucleic acid (RNA)  It is a nucleic acid that is present in the majority of living organisms and viruses.  It is made up of nucleotides, which are ribose sugars attached to nitrogenous bases and phosphate groups.  The nitrogenous bases include adenine, guanine, uracil, and cytosine.  RNA mostly exists in the single-stranded form. Actively involved in transcription and translation process.  Major Types of RNA messenger RNA (mRNA) mRNA is made from a DNA template. Its role is to carry protein information from the DNA in a cell’s nucleus to the cell’s cytoplasm.  transfer RNA (tRNA) Serves as a link (or adaptor) between the mRNA molecule and the growing chain of amino acids that make up a protein.  ribosomal RNA (rRNA) Helps to form the structure of ribosome, binds mRNA and tRNA to ribosome and directs the translation of mRNA into proteins.