5 SANES CH 5.2 only 2009 (1)

5 SANES CH 5.2 only 2009 (1) - SANES Chapter 5 Part 2:...

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SANES Chapter 5 Part 2: Molecular mechanisms of axon guidance
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Remember that adhesion allowed the growth cone to be pulled forward by actin- myosin 'contraction'. adhesion---actin-myosin contraction---new actin-assembly for filopodial elongation---new adhesion make the growth cone move forward.
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Three Important Extracellular Matrix Molecules 1. Laminin 2. Fibronectin 3. Collagen Different axons grow best on different substrates, thus differential adhesion is also a guidance mechanism Plot of 2 groups of neurons
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Growth cone adhesive molecule that is also a selective substrate receptor There are 18 alpha and 9 beta Integrin subunits Actin Filaments link to the intracellular domain of the integrin receptor Note that different combinations of receptor subunits bind to different extracellular matrix molecules Calcium Independent Adhesion Calcium Dependent Adhesion Three major families of adhesion molecules and their linkage to other structures e.g. NCAM and L1
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Laundry list of adhesive molecules found at synapses just to highlight the importance of adhesion at synapses
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Stability Target recognition Synaptic differentiation Regulating Structure Role of adhesion molecules in synapse formation and stabilization Important: most adhesion molecules are signaling devices Synaptosome
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How is axon guidance actually accomplished?
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Axon guidance occurs through direct contact with the growth cone (contact adhesion or contact repulsion) and through distance signaling (long range attraction or long range repulsion).
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(Drosophila CAM) found in only certain axons Drosophila CAM Drosophila CAM (Fas II) knockouts disorient the longitudinal axon guidance
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Commissural axons Fas II in Longitudinal axons Drosophila CAM’s Drosophila CAMS guide axons down the connectives and across the midline Fas II is expressed in the longitudinal direction and Fas I in the commissures. Confocal micrograph of labeled
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5 SANES CH 5.2 only 2009 (1) - SANES Chapter 5 Part 2:...

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