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. Author manuscript; available in PMC: 2014 Jun 19.
Published in final edited form as: Nat Rev Neurosci. 2014 Jan;15(1):7–18. doi: 10.1038/nrn3650

Figure 2. Cytoskeletal reorganization at different stages of axon branching.

Figure 2

a | Membrane protrusion requires the accumulation of actin filaments, which can form patches81–83. In (a) membrane protrusion requires actin nucleation (ARP2/382,83 and Cordon-bleu88), actin branching (ARP2/3) and actin elongation (Ena/VASP)35. Cofilin is important for the turnover of actin filaments92 and Septin 6 is localized to the actin patch110. MTs are stabilized by MAPs (Tau//Doublecortin)78,99,103 in the axon but are also capable of extending at their plus ends (APC/EB proteins)100,101. b | Filopodia, which contain bundled actin filaments, emerge from the axon shaft accompanied by localized splaying and fragmentation of MTs55,80,93,96,97; these invade the filopodium and extend along actin bundles. MTs are severed by Spastin and Katanin98. Septin 7 promotes the entry of MTs into the filopodium110. c, d | Stable MTs enter the nascent branch (c), which continues to mature and extend; this growth is led by a motile growth cone (c, d). MAPs protect some of the MTs in the axon shaft from severing (c, d). Within the axon branch MTs become bundled and stabilized by MAPs (d).