Explained : How Epigenetics alters Inherited Genetics ? | UPSC
How epigenetics alters inherited genetics’ message
WHY IN NEWS:
An exciting paper has appeared in Nature, authored by Lu et al titled “Reprogramming to recover youthful epigenetic information and restore vision”.
SYLLABUS COVERED: GS 3: Science : Biology : Cell Structure
For PRELIMS it is important to understand the science behind ageing . Go through the concept of RCG’s . It is very important !
For MAINS describe the role of protein in cell structure . Let us dive in !
WHAT IS EPIGENETICS?
- Epigenetics is the study of heritable changes in gene expression (active versus inactive genes) that do not involve changes to the underlying DNA sequence.
- It is a change in phenotype without a change in genotype — which in turn affects how cells read the genes.
- Epigenetic modifications can manifest as commonly as the manner in which cells terminally differentiate to end up as skin cells, liver cells, brain cells, etc.
- Or, epigenetic change can have more damaging effects that can result in diseases like cancer.
Representation of the chromatin structure, including histones and DNA, which become available to epigenetic marks | Sources : epigenetic.com
- If one can put them back by restoring them using specific genes (gene therapy) sight can be restored.
- The human (and mammalian) eye is a remarkable organ in the course of evolution which has allowed us to “see” the external world clearly and in colour.
- It is the retina that sends the message to the brain. Its main component, called the retinal ganglion cells (RGC).
- RCG are the ones that help in this process of sending the message in the form of electrical signals, called neurons or nerve cells.
- Thus, RGCs are the ones that convert optics into electronics.
- The functioning of cells and tissues in our body are controlled by thousands of proteins that regulate various cellular functions.
- Any minor or major changes to our inherited DNA (addition or mutation) can result in altered protein production.
- This in turn leads to defective cellular functions. This forms the basis for many heritable genetic disorders affecting the mankind.
- There are other biochemical changes too that influence and dictate if a gene should be active or inactive in a given cell type.
- However, it is allowed to express only in the insulin secreting beta cells of the pancreas and is kept inactive in the rest of the cells of the body.
- This phenomenon is tightly regulated by a combination of regulatory proteins that changes the expressivity of the gene.
- The histone proteins that bind the DNA and help to compactly wrap it inside the chromosomes .
- Histone proteins can undergo chemical modifications such as methylations and acetylations on different lysine amino acids within the protein.
- These modifications both on the DNA and its associated proteins alter the chromosomal conformations and regulate gene expression.
- Such biochemical changes that dictate the expressivity of a gene in a particular cell are collectively termed “epigenetics.”
- Epigenetic changes are reversible and are mediated by regulatory proteins.
- DNA methyl transferases (DNMTs)
- Istone acetyl transferases (HATs)
- Histone deacetylases (HDACs) and so on.
- This normal epigenetic control on our genes can get altered during normal ageing, stress and disease conditions.
- In many cancers, there are a certain set of genes called tumour suppressors that regulate cell division.
- Similarly many messages or youthful genes are also turned off by epigenetic changes during our normal ageing process.
- RGCs help us the ability to see clearly and in colour.
- In addition, external factors such as family or hereditary history, diabetes (both type 1 and 2)play vital role in inducing “epigenetic”.
- New and ongoing research is continuously uncovering the role of epigenetics in a variety of human disorders and fatal diseases.
SOURCES: THE HINDU | Explained : How Epigenetics alters Inherited Genetics ? | UPSC