Epigenetics
- 2. What is Epigenetics? • Epigenetics is the study, in the field of genetics, of cellular and physiological phenotypic trait variations that are caused by external or environmental factors that switch genes on and off and affect how cells read genes instead of being caused by changes in the DNA sequence. • A change in phenotype without a change in genotype
- 4. Why study Epigenetics? • Epigenetic contributions to disease fall into two classes. One class involves genes that are themselves regulated epigenetically, such as the imprinted genes associated with Angelman syndrome or Prader-Willi syndrome. Clinical outcomes in cases of these syndromes depend on the degree to which an inherited normal or mutated gene is expressed or not.
- 5. • The other class involves genes whose products participate in the epigenetic machinery and thereby regulate the expression of other genes. For example, the gene MECP2 (methyl CpG binding protein 2) encodes a protein that binds to specific methylated regions of DNA and contributes to the silencing of those sequences. Mutations that impair the MECP2 gene can lead to Rett syndrome
- 6. Why study Epigenetics? • Cancer was the first human disease to be linked to epigenetics, in 1983. An accumulation of genetic and epigenetic errors can transform a normal cell into an invasive or metastatic tumour cell Subsequently, epigenetic changes can be used as biomarkers for the molecular diagnosis of early cancer
- 7. • One of the most promising areas of epigenetic investigation involves stem cells. Epigenetic mechanisms play a key role in defining the “potentiality” of stem cells. It may become possible to intervene and effectively alter the developmental state. The implications of this work for future clinical regenerative intervention for conditions ranging from trauma to neurodegenerative disease are profound.
- 8. • Covalent modifications- The first way is post translational modification of the amino acids that make up histone proteins The second way is the addition of methyl groups to the DNA, mostly at CpG sites, to convert cytosine to 5- methylcytosine.
- 9. Epigenetics mechanisms • RNA transcripts • MicroRNAs • Structural inheritance • Nucleosome positioning