Epigenetics V: Modes of Epigenetic Inheritance

Question 1

What is the preferred substrate for DNMT1 in vitro?

Answer 1

Hemi-methylated DNA

Question 2

DNMT1 associates with sites of DNA ______________ in S phase via PCNA interaction

Answer 2

Replication

Question 3

DNMT1 associates with which protein that binds specifically to hemi-methylated DNA?

Answer 3

UHRF1

Question 4

What helps direct DNMT1 action and can re-inforce DNMT1 function by recruiting UHRF1?

Answer 4

H3K9 methylation

Question 5

Polycomb protein complexes PRC1 and PRC2 regulate one another through (positive/negative) feedback

Answer 5

Positive

Question 6

What domain of PRC2 methylates K27 and modifies K27?

Answer 6

Ezh2 methylates K27 and Eed modifies K27

Question 7

What domain of SUVAR39 methylates K9 and modifies K9?

Answer 7

Chromodomain modifies K9 and SET domain methylates K9

Question 8

What happens to histones during DNA replication?

Answer 8

Daughter DNA strands carry a combination of old and new nucleosomes

Question 9

Copying mechanism occurs from previously (unmethylated/methylated) histones to (unmethylated/methylated) histones

Answer 9

Methylated (old); unmethylated (new)

Question 10

What ensures that new histones use old histones as a template?

Answer 10

Interaction between old histones and components of the replication machinery

Question 11

What composes the PCR2 dinucleosome?

Answer 11

One monomer that is unmodified and one monomer that already has H3K27me

Question 12

Which subunit is bound to H3K27me3 nucleosome and which subunit is bound to unmodified nucleosome?

Answer 12

Eed; Ezh2

Question 13

Which nucleosome activates the enzymatic activity of the complex?

Answer 13

Eed bound to H3K27

Question 14

What experiment was done to observe transgenerational epigenetic inheritance?

Answer 14

Expose parent to stress or change of nutrition and measure physiological effect on the parent to see if it was passed on to future generations

Question 15

Which of the following corresponds to either transgenerational or intergenerational inheritance?
a. Due to transmission of an epigenetic change to gametes independently of the initial exposure
b. Due to initial, direct exposure of gametes in F0

Answer 15

a. Transgenerational
b. Intergenerational

Question 16

Transposon insertion in color gene promoters and variable DNA methylation in transposon are models to study (intergenerational/transgenerational) epigenetic inheritance

Answer 16

Transgenerational

Question 17

How does low maternal care lead to CpG methylation in the promoter of the gene for glucocorticoid receptor in the hippocampus in pups?

Answer 17

Low maternal care leads to blocked transcription factor binding, which contributes to low levels of glucocorticoid receptors and high corticosterone levels in pups

Question 18

True or false: Changes in paternal diet/metabolism do not affect sperm and health of offspring

Answer 18

False

Question 19

Are DNA methylation and histone modifications mechanisms for transgenerational effects transmitted through the male germline?

Answer 19

No

Question 20

What could be mechanisms for transgenerational effects transmitted through the male germline?

Answer 20

Small RNAs, metabolites, microorganisms

Question 21

Why are histone modifications not a mechanism for transgenerational inheritance?

Answer 21

Most histones are removed and replaced with protamines in the late stages of sperm development

Question 22

piRNAs are involved in what mechanism?

Answer 22

Silencing transposons in the germline

Question 23

What is the role of small RNAs in transcriptional silencing and epigenetic inheritance?

Answer 23

Forming heterochromatin

Question 24

Which small RNAs don’t affect transcription and act on highly repetitive sequences?

Answer 24

siRNAs; piRNAs