lecture 12- neurotrophins and apoptosis Flashcards
state the 2 points of the neurotrophic factor hypothesis
neurones are produced in excess of need and the excess is eliminated over time
neurotrophic factors emanate from targets to promote survival according to tissue size
what is the proof for the neurotrophic factor hypothesis
in limb bud experiments, extra targets lead to more neurons and less targets lead to less neurons
what does the number of cells surviving correlate with
the size of the tissue innervated
what are the 2 classes of apoptosis genes
anti apoptotic- prevent cell death
pro apoptotic- required for cell death
what are the 2 classes of caspases
initiator
executioner
what is nerve growth factor
a neurotrophic factor that prevents apoptosis in neurons so they can form circuits
what does trophic mean
supports survival and growth
what does tropic mean
directs the movement
is NGF tropic or trophic
both
what is special about Pro NGF and what does this mean
it actually induces apoptosis so different states of the same protein have opposite effects
describe NGF signalling
use TRKs
singnalling endosome formed
what does the MAP pathway regulate
transcription
what does the Akt pathway regulate
apoptosis
what is cell death also useful for, apart from size control
removing transient structures ie. subplate neurons
what 2 things is NGF needed for
cell and neuron survival
what is the high affinity receptor called
TrKA
what is the low affinity receptor called
p75-NTR
what is special about the p75-NTR receptor
all forms of NTs can bind to it, even inhibitory ones
which pathway does NGF deprivation activate
caspase 6
what does blocking death receptors do
save axons
even without NGF
why is the p75NTR receptor called a dependance receptor
it will initiate apoptosis in the abscence of a ligand
