DNA methylation
- Created by: natasha8sherry
- Created on: 15-11-13 11:35
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- DNA methylation
- The 5' position of cytosines in CpG dinucleotides can be methylated to methylcytosine
- Genes with the POTENTIAL to be transcribed are NOT methylated
- During differentiation genes are marked as being "inactive" by methylation + kept like this for life
- Requires 2 enzymes:
- Maintenance Methylase (Hemi-methylases)
- Pass methylation patterns on after DNA replication
- Methylating cytosine residues on 1 strand when other is methylated
- Continues through life-time to maintain pattern of methylation
- A mutation in this gene will activate gene expression
- Ectopic expression of genes
- Can lead to cancer - demethylated oncogenes switched ON
- Ectopic expression of genes
- De novo methylases
- First methylate DNA. Mechanisms unknown
- Maintenance Methylase (Hemi-methylases)
- Methyl-CpG
- HDACs recruited
- Methylating, repressive marks promoted on histones
- Silencing by heterochromatin protein 1 (HP1)
- Methylating, repressive marks promoted on histones
- HDACs recruited
- Abberant DNA methylation
- Contributes to disease - E.g. the leukemia myelodysplastic syndromes (MDS)
- 5-azacytidine + 5-aza-2'deoxycytidine can be incorporated into DNA artificially and cannot be methylated
- Leads to activation of gene expression
- Therefore can be used as a drug to reverse effects of abberant DNA methylation
- Contributes to disease - E.g. the leukemia myelodysplastic syndromes (MDS)
- Therefore can be used as a drug to reverse effects of abberant DNA methylation
- Leads to activation of gene expression
- The 5' position of cytosines in CpG dinucleotides can be methylated to methylcytosine
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