epigenetic and the inheritance of chromatin structure Flashcards
how is epigenetic memory of transcription achieved?
through reconstruction of the same chromatin structure after the passage of the replication fork
how is epigenetic control maintained? what do we call this?
by DNA methylation and methylation and acetylation of histones. we call this epigenetic marks
when are epigenetic marks faithfully rebuilt?
during and/or soon after the passage of the replication fork
what does methylation of CpG islands lead to?
condensation of chromatin
what does methylated DNA recruit?
special class of Me-DNA-binding proteins (MeBPs)
what does MeBPs recruit ?
factors that deacetylate histones and condense chromatin
what does unmethylated CpG islands recruit?
proteins that methylate a specific position on histones: histone 3-lysine 4 (H3-K4)
what is H3-K4 recognized by and what does it dictate?
recognized by the transcription initiation machinery as an epigenetic mark that dictates gene expression
when is the methylation of DNA rebuilt?
immediately after the passage of the replication forks
what can methylation of CpG islands in the promoter of the tumour suppressor genes block and promote?
their expression and promote cancer
CpG islands hypomethylated = ???
tumor supressor gene active
CpG island hypermethylated = ???
tumor supressor genes inactive
what are the sites of modification for Lysine?
- H3 (K4) Me3 in promoter regions
- H3 (K4) Me1 in enhancers
- H3 (K9, K27)
what are the effects on transcription in
- H3 (K4) Me3 in promoter regions
- H3 (K4) Me1 in enhancers
activation
what is the effect on transcription in - H3 (K9, K27)
repression
