He's got a nice reporter system (synthetic biology) to look at recruitment of repressor complexes to DNA,
and how these complexes control chromatin accessiblity and thus stem cell dynamic, ie staying pluripotent
maintaining a differentiated state.
Polycomb repressive complex
PRC1 and 2 which induces repression both canonical vs variant forms.
Proxy proteins :
CBX and RYBP
Looking at DNA methylation
Map where these proteins bind
Found shared and variant specific sites for binding.
Showed how his reporter can give a readout of PRC1 binding and repression.
Uses tet O site GFP reporter
example: synthetic RYBP or CBX binding and repression is different depending context of reporter.
(caveat is the reporter doesn't completely mimic chromatin)
Neat feature of reporter is that you can add DOX to eliminate binding and derepress reporter
Focus on heterochromatin silencing and transposable elements
LINEs, SINEs, ERVs
These elements evolutionarily want to move and jump around the genome.
Interested in how have we've evolved to control these movable elements ?
Used CRISPR screen with reporter to fish out genes required to maintain repressive state.
3. zfp462 !!!
zfp462, mostly made up of zinc fingers and undefined regions (disordered until binding and interaction with partners induces ordered state?). Still, the gene is highly conserved...
Het mutation in human causes Weiss Kruszka
- Multi organ don't form
- Dygenesis of corpus callosum
Used reporter and synthetic ZFP and found it is sufficient to induce repression.
Further deletion analysis found the C-terminal domain is sufficient for repression
Did Mass Spec (MS) to find for interactors and confirmed repression complex in heterochromatin by fishing out HP1 as hit.
The last bit of the talk looked at how ZFP might be involved in neuronal differentiation.
Embryonic stem cells are formed into EBs and induced to make germ layers:
Using ngn2 to induce neurons
and found ZFP involved in regulating Endothelial genes, to repress them in neurons
Found ZFP bind intergenic regions associated with transposable elements, which fits