Bio-317 - lecture #22, new version [Compatibility Mode]

Bio-317 - lecture #22, new version [Compatibility Mode] -...

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Unformatted text preview: 11/22/2011 1 The Signaling Events of Axon Guidance Maya Shelly E.mail: maya.shelly@stonybrook.edu Office Location: Room 530, Life Science Bldg. Office Hours: Tuesday, 12:30 PM - 1:30 PM, November, 2011 Target to innervate Axon Guidance or Pathfinding * Process by which neurons send axons to reach and innervate correct targets a very precise process where the axons follow very precise paths in the nervous system to reach the correct target. + + + + Molecular Cues to innervate Intermediate Axon + + + + + + + + + + + + + + + +---- Gradients of Positive and Negative Molecular Cues Molecular Cues Intermediate target target + + + + + + + + +---------------- 11/22/2011 2 * Growing axons have a highly motile structure at the growing tip - Growth Cone . Growth Cone Turning in Axon Guidance * Growing axons have a highly motile structure at the growing tip - Growth Cone . * The growth cone reacts to the extracellular environment : The extracellular environment possesses molecular cues, soluble molecules Growth Cone Turning in Axon Guidance The extracellular environment possesses molecular cues, soluble molecules secreted into the environment or bound molecules (like the extracellular matrix proteins), that instruct the axon to which direction to grow and navigate. * The growth cones express on their cell-surface receptors for these external cues. * The extracellular/receptor interaction leads to activation of intracellular signaling events . * These molecular cues can be attractive to the growth cone or repulsive : and are translated into a turning response of the growth cone chemotropic response : Attraction turning of the growth cone towards the molecular cue, Repulsion turning of the growth cone away from the molecular cue. 11/22/2011 3 * These signaling events eventually affect the cytoskeleton to perform the turning. Growth Cone Turning in Axon Guidance Growth Cone - Xenopus (frog) spinal neuron growth cones- Actin and Microtubule cytoskeleton in the growth cone- Distribution of F-actin ( red ) and microtubules ( green ) in the growth cone,- Actin filaments are predominant in the peripheral domain, whereas bundles of microtubules are- whereas, bundles of microtubules are localized to the central domain,- Free microtubules can also penetrate into actin filopodia and lamellipodia (arrowheads). * These signaling events eventually affect the cytoskeleton to perform the turning. Growth Cone Turning in Axon Guidance Growth Cone Turning induced by Gradient of diffusible factors- Xenopus (frog) spinal neuron growth cones + + + + + + + + + + + +------------------ 11/22/2011 4 Netrin The Signaling Events of Axon Guidance: Axon Guidance Molecules and their Receptors (4) Netrins- secreted molecules that attract or repel axons: Attraction is mediated by binding to the DCC (D eleted in C olorectal C arcinoma) receptor, Repulsion is mediated by binding to the UNC5 receptor....
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This note was uploaded on 12/06/2011 for the course BIO 317 taught by Professor Simonhalegoua during the Spring '08 term at SUNY Stony Brook.

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Bio-317 - lecture #22, new version [Compatibility Mode] -...

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