Thursday, January 30, 2014

Axon Guidance part 3

1Modulation of Response to axon guidance cues¶

• response to a specific group vary

  • among different populations of neurons
  • at different envrionment
  • at different time

• cAMP level can switch neuron's response to guidance cues

• other levels of control

  • transcriptional control fo receptor expression

  • local translation of receptors within the growth cone

    • EphA2 expression is activated after growth cone crosses the floor plate
    • this is shown by fluorescent-tag its 3' UTR

  • post translational modification of receptor - shedding

    • metalloprotease cleaves off / shed the receptors like DCC
      • makes cells less responsive to netrin -1
    • metalloprotease inhibitors potentiate responses to netrin-1

  • receptor silencing - slit-robo signaling

    • Netrin attract axons to midline via signaling through DCC
    • once axon crosses the midline,
      • repulsion by slit expressing in the midline
      • robo is upregulated, binds to DCC, inhibit attractive response to netrin
    • this prevents axon from re-entering the midline