A Subtle Network Mediating Axon Guidance: Intrinsic Dynamic Structure of Growth Cone, Attractive and Repulsive Molecular Cues, and the Intermediate Role of Signaling Pathways

Figure 2

Schematic illustration of highly dynamic structure of a growth cone: dense microtubules located in the central domain that extend from axonal shaft to a growth cone to support growth cone movement and to serve as the tracks for transport of membranous organelles. In the peripheral domain, there are bundled actin filaments (F-actin bundles) retracting at similar rates at the leading edge and a network of short and branched actin filaments (F-actin network). Sometimes microtubules also explore the peripheral domain. (b) Schematic illustration of actin-based growth cone motility: attractive cues lead growth cone to protrude towards them. Protrusion is resulted from inhibited retrograded actin flow, where continued polymerization of actin at the leading edge, myosin motors, and microtubules rearrangement is involved. On the other hand, repulsive cues lead to actin filaments and microtubules dissolution and cause growth cone collapse that triggers the repulsive response towards the repulsive cues.

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