Axon Outgrowth & Synaptic Formation Flashcards
What structures are used for navigation & elongation in axon outgrowth?
Lamellipodia & filopodia
(growth cones extend)
What other structures are required in axon outgrowth?
Microtubules and actin polymerisation using ATP
What is the function of cytocholasin?
(a fungal toxin)
Blocks actin polymerisation & immobilises growth cone
What guides axon pathfinding?
Attractive & repellant cues
What governs stalling and retraction (in axon outgrowth)?
Growth cone regulation by intracellular Ca2+ dependant kinases
What do cell-adhesion molecules (CAMs) allow?
Bundling of axons together in fascicles
What do extracellular matrix (ECM) adhesion molecules define?
Growth pathways over matrix substrates
In axonal pathfinding, what dominates in early outgrowth, and what finalises the synaptic patterns?
Chemical signals [EARLY]
Activity (experience) [FINALISES]
What is nerve growth factor (NGF)?
What does it do?
A neurotrophin
- Binds to neurotrophin R TrkA
- Stimulates PNS outgrowth & protects CNS neurons after injury
What role do neurotrophins play in (early) Alzeimer’s?
- Loss of cholinergic (an ACh-using neuron) neurons
- Decreased NGF R (Trk)
What was the outcome of the TrkA knockout in mouse?
TrkA knockout in forebrain = loss of cholinergic networks & deficits in cognition
What chemical cues regulate axonal outgrowth?
NETRIN (attractant)
SEMAPHORINS & EPHRINS (repellant)
What are the 2 classes of chemical cues?
LONG range
SHORT range
(ECM & adhesion molecules)
In in PNS, what do myelin-producing glial cells do?
Growth promoting effect
- attract growth cones
- enable REGENERATION
In in CNS, what do myelin-producing glial cells do?
Repress growth with inhibitory factors
