Epigenetics 4 Flashcards
What does too much stem cell self renewal cause?
Hyperplasia
What does too much stem cell differentiation cause?
Small organs
In asymmetric division, what do neural stem cells in drosophila divide to produce?
Self renew and ganglion mother cell
What is polarity in stem cell division?
Apical and basal alignment of protein during division
Does prospero align in the basal or apical cortex during asymmetrical division of stem cells?
Basal
What is DAM ID?
Attach DNA binding protein to E.coli enzyme which methylates adenine at GATC sites. Sites of methylated adenine indicate binding site of protein (e.g. prospero/lola)
What region of cyclin E gene does prospero bind?
introns
What did an RNA seq expression array reveal that prospero repressed?
neutral stem cell genes e.g. cyclin E
What happens to stem cells when prospero is knocked out?
Continuation of self renewal
What sequence was found conserved near prospero binding sites?
GATCG - binding site for lola
What binds the DNA sequence GATCG?
lola
What was used to identify lola as the DNA binding protein of sequence GATCG?
yeast 1 hybrid using His-3 marker protein
What is the structure of lola?
BTB zinc finger
What is the role of lola?
Transcription factor
What is the role of prospero?
Transcription factor
How many isoforms of lola were found?
25
How many isoform of lola that have zinc fingers were there?
17
What kind of cell is lola expressed in?
Post mitotic neurons in drosophila
Do most lola targets overlap with prospero targets?
yes
What is the function of lola?
To maintain a cell in a differentiated state by repressing neural stem cell genes. It also represses genes that have already been switched off by prosper
What happened when MARCM was used to knock out lola in drosophila?
tumour formation because of dedifferentiation of cells
Can removal of lola causes dedifferentiation of mature neurons?
No, this is controlled by other factors interacting with lola
What was used to identify binding partners of lola?
yeast 2 hybrid screen - found over 100 hits
Give example of factors that interact with lola to prevent dedifferentiation?
NuRD complex
Histone deacetylates
permanently repress even when lola is removed
What were 60% of lola hits from the yeast 2 hybrid screen?
lncRNAs
Is lncRNA segregated into GMC in the same way as prospero?
yes
What was lncRNA found to express?
micro-peptide 1
How many many amino acids in micro-peptide- 1?
30aa
What is the function of micro-peptide 1?
interacts with lola to prevent it from acting too early in differentiation
What is the hippo pathway?
Cascade that results in repression of Yorkie (YAP)
What does overexpression of yorkie (YAP) cause?
more proliferation of epithelium cells
What has been found up regulated in melloblastomas?
YAP
Yorkie causes symmetric division of stem cells. True or false?
True
What is the affect of hippo pathway on symmetrical divsion of stem cells?
inhibitory - blocks yorkie (YAP)
What is the notch pathway?
Delta ligand on one cell interacts with notch receptor on another. Causes gamma-secretase to cleave the intracellular region of notch (Rbpj) which translocates to the nucleus and promotes symmetrical division of stem cells
What is the affect of notch pathway on symmetrical divsion of stem cells?
promotes symmetrical division
Is notch a proto-oncogene?
yes
What is the affect of KO Rbpj?
more asymmetric division, reduced size of cortex
How does notch suppress growth?
different cellular context
Could gamma-secretase inhibitors be a potential theraputic?
yes
