Axon Growth Flashcards
Rho-GTPases
Guidance cues linked to these molecular switches
- regulate actin-binding and MT binding
Repulsive Cues
Semaphorin 3A and Ephrin A
- switch on RhoA
- Decreases GC protrusion
- actin depolymerisation
Attractive Cues
Neurotrophin and Netrin
- switch on Rac1 and Cdc42
- Increases GC protrusion
- actin polymerisation
What does floor pate secrete
Shh and Netrin
Types of GCs
Canonical
Non-canonical
Netrin receptors
DCC and UNC5 (attractive)
Semaphorins
Plexins and Neurophilins (repulsive)
Slits
Robo receptors (repulsion)
DCC only netrins
attractive cue
DCC and UNC5 netrins
repulsive
Netrin (receptor + Rho GTPase)
Netrin -> DCC -> Rac
Semaphorin (receptor + Rho GTPase)
Semaphorin -> Plexin/ NPN -> Rho
Ephrin (receptor + Rho GTPase)
Ephrin -> Robo -> Rho
GPI
repulsive guidance molecule (RGM)
- ephrins
Ephrin A
repulsive GuidC - GC collapse
Ephrin A and Eph A
Ephrin A binding to receptor (Eph A) induce GC collapse - axon CANT move further
Nasal & ?
Posterior
Temporal & ?
Anterior
Retina Ephrins
Eph Bs and Eprhin Bs
Wnt3a
cooperates with EphB-ephrin B1 to regulate D-V mapping
Highest Ephrin A expression
Caudal SC
Lowest Ephrin A expression
Rostral SC
Highest Ephrin B expression
Medial SC
Lowest Ephrin B expression
Lateral SC
Highest Eph A expression
Temporal Retina
Lowest Eph A expression
Nasal retina
Highest Eph B expression
Ventral retina
Lowest Eph B expression
Distal retina
Whats crucial for R-C mapping
Ephrin A2/5 binding to Eph A3 induces GC collapse
Whats crucial for D-V mapping
EphrinB binding EphB repels GC - chemorepulsion
