Lecture 10 Flashcards
what can be thought to define a cell type?
transcription factors - turn on genes
what are the 3 things that have to be reset for cloning?
1) gene expression- somatic genes turned off and embryonic genes turned on
2) methylation - reset back to totipotent configuration
3) chromatin - remodelled
what are IPS cells?
induced pluripotent stem cells - a type of pluripotent stem cells that can generated directly from adults
what are 2 things you need to do to make IPS cells?
1) make sequential chromatin
2) gene expression changes
what are 3 types of approaches for non-integrated delivering of reprogramming factors?
1) vector based approaches
2) protein based
3) chemical based reprogramming
what is a transposon?
DNA sequence that can change its position within a genome - can create and remove mutations
what is the name of the enzyme that binds to the end of a transposon and what does it do?
transposase - catalyses the movement of the transposon to another part of the genome
what are 5 vector based approaches for delivery of reprogramming factors?
1) virus
2) mRNA
3) adenovirus
4) episomal
5) transposon
what is episomal replication?
can replicate independently and remain outside the chromosome
describe the cell state metaphor?
if you think of cell states as a bumpy landscape - depending on where the cell lays will affect the probability of transitioning from one state to another (not equal for all cells) - the higher the hill the harder to transverse and therefore the more stable cell state - valleys = epigenetic restriction
what blocks jumping between lineages?
barriers - they may be of different heights but can be overcome with the correct factors
why is the induction of pluripotency slow?
because different signals could send you ‘off course’ - getting the cell into the correct cell state is difficult - could be any signal
how do you identify successful IPS colonies?
1) morphology - surface markers and transcription factors associated with the pluripotent state
2) protein expression/gene expression -
3) differentiation - see if they make all 3 germ layers
4) epigenetics - methylation at pluripotent loci
what cells have iPS cells been derived from?
1) ectoderm
2) mesoderm
3) endoderm
4) germ cells
- in reality it appears any cell can be reprogrammed to an iPS cell
whats the difference between iPS cells and ES cells and the significance of it?
iPS cells carry the genotype of the parent cells - this means you have captured a particular genotype potentially forever (they grow indefinitely) therefore you could potentially make iPS cells from different genotypes including people with disease and use them for drug discovery
