Epigenomics-OG

Epigenomics

 

"Epi">>reversible

 

definition : modifications on  DNA /histones

• alter the DNA sequence

 

• Tumorigenesis : cancer --> expression / regulation change

 

feature

• regulate gene expression : turn on / off 
• not part of a DNA sequence , but in some cases , they can be inherited to offspring
• In general, methylation turn off the gene expression while acetylation turn on the gene expression

 

histone modification

• DNA methylation
• • DNA methylase (DMNT)
  • effect
  • • imprinting : transfer certain environmental factor
    • X-chromosome inactivation
    • Heterochromatin maintenance
    • Developmental controls
    • Tissue specific expression controls
  • How to sequence methylation?
  • • Biosulfite treatment of cytosine : cytosine --> uracil ( 5-methylcytosine residues is unaffected)
• DNA acetylation
• DNA phosphorylation
• DNA ubiquitination
• SUMOylation
• ADP-ribosylation
• deamination

 

How to detect histone modification?

• Chip-Chip : chromatin immunoprecipitation with DNA microarrays
  • immunoprecipitation : specific antibodies are used to immunoprecipitate the DNA-histone complexes
  • visualization : purify immunoprecipitation --> amplification --> labeled with fluorescent tag

 

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reference

1) https://en.wikipedia.org/wiki/Epigenomics

2) https://ghr.nlm.nih.gov/primer/howgeneswork/epigenome