Lecture 10 - Epigenetics Flashcards
epigenetics can be defined as: ……. changes in gene expression that are……. a consequence of change in ….. sequence
heritable
not
DNA
how can epigenetics be modified, 2 ways?
environmentally and pharmacologically
name 3 markers of epigenetics
DNA methylation, histone modifications and miRNA
to which position is a methyl group added to the cytosine ring in DNA methylation?
position 5
name the 3 DNA methyltransferases involved in the catalysis of DNA methylation
DNMT1, 3a, 3b
after the addition of a methyl group to the cytosine ring of DNA in DNA methylation what is cytosine’s new name?
5-methylcytosine
at which dinucleotides does DNA methylation only ever occur at?
CpG
true or false, the pattern of DNA methylation is not stably inherited?
false, it is
what percentage of CpGs are methylated?
70%
true or false, the genome is CpG poor?
true
which version of cytosine is prone to mutation?
J-cytosine
in transcriptional repression within DNA methylation, which 2 molecules bring in large complexes to compact chromatin and prevent transcription factors binding?
MBD3, MBD2
where in the body and also on which type of cells is there lots of non CpG methylation?
brain, ES cells
is hydroxy methylation copied by DNMT1?
no
name the 4 possible histone modifications
acetylation, methylation, phosphorylation, ubiquitination
in histone modification, acetylation can do which 3 things?
activation, decompaction of chromatin, permissive
is methylation in histone modifications permissive or non permissive when associated with K9-H3, K27-H3?
non-permissive
name the 3 roles of methylation in histone modification on K9-H3 and K27-H3?
inactivation, compaction, non-permissive
name the 2 sets of residues upon which methylation of histones can occur causing INACTIVATION
K9-H3
K27-H3
name the set of residues upon which methylation of histones can occur causing ACTIVATION
K4-H3
true or false CpG sites exhibit a low frequency of mutation and are upheld in cancer?
false, they are highly mutational and have a loss of regulation in cancer
if the DNA methylation age is greater than the chronological age, what happens to life expectancy?
decreases
high CpG island methylation is associated with a …… risk of frailty?
increased (by 50%)
licking and grooming behaviour of animals is associated with reduced stress in adulthood and increased expression of glucocorticoid receptor in hippocampus. Is it also associated with a loss or an increase of methylation of GR which persists into adulthood? why?
loss, because methylation reduces gene expression by repressing txn
does methylation reduce or increase txn levels and gene expression levels therefore?
reduces txn and gene expression
in the dutch hunger winter, lower levels of methylation on which gene occurred?
IGF2
HATs and HDACs do what to histones?
hats add an acetyl, hdacs remove
in cancer, mutations of genes controlling the structure of what is associated with epigenetics?
chromatin
