title: Drebrin coordinates the actin and microtubule cytoskeleton during the initiation of axon collateral branches.
abstract: Drebrin is a cytoskeleton-associated protein which can interact with both actin filaments and the tips of microtubules. Its roles have been studied mostly in dendrites, and the functions of drebrin in axons are less well understood. In this study, we analyzed the role of drebrin, through shRNA-mediated depletion and overexpression, in the collateral branching of chicken embryonic sensory axons. We report that drebrin promotes the formation of axonal filopodia and collateral branches in vivo and in vitro. Live imaging of cytoskeletal dynamics revealed that drebrin promotes the formation of filopodia from precursor structures termed axonal actin patches. Endogenous drebrin localizes to actin patches and depletion studies indicate that drebrin contributes to the development of patches. In filopodia, endogenous drebrin localizes to the proximal portion of the filopodium. Drebrin was found to promote the stability of axonal filopodia and the entry of microtubule plus tips into axonal filopodia. The effects of drebrin on the stabilization of filopodia are independent of its effects on promoting microtubule targeting to filopodia. Inhibition of myosin II induces a redistribution of endogenous drebrin distally into filopodia, and further increases branching in drebrin overexpressing neurons. Finally, a 30 min treatment with the branch-inducing signal nerve growth factor increases the levels of axonal drebrin. This study determines the specific roles of drebrin in the regulation of the axonal cytoskeleton, and provides evidence that drebrin contributes to the coordination of the actin and microtubule cytoskeleton during the initial stages of axon branching. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1092-1110, 2016.
authors.affiliation: Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, 3500 N. Broad St, Philadelphia, Pennsylvania, 19140.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ketschek
authors.affiliation: Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, 3500 N. Broad St, Philadelphia, Pennsylvania, 19140.
authors.forename: Mirela
authors.initials: M
authors.lastname: Spillane
authors.affiliation: Peninsula Schools of Medicine and Dentistry, University of Plymouth, Plymouth Science Park, Research Way, Plymouth, PL6 8BU, United Kingdom.
authors.forename: Xin-Peng
authors.initials: XP
authors.lastname: Dun
authors.affiliation: RILD Building, University of Exeter Medical School, Wellcome Wolfson Medical Research Centre, Barrack Road, Exeter, EX2 5DW, United Kingdom.
authors.forename: Holly
authors.initials: H
authors.lastname: Hardy
authors.affiliation: RILD Building, University of Exeter Medical School, Wellcome Wolfson Medical Research Centre, Barrack Road, Exeter, EX2 5DW, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Chilton
authors.affiliation: Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, 3500 N. Broad St, Philadelphia, Pennsylvania, 19140.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Gallo
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001369:Axons / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D002642:Chick Embryo; D018274:Electroporation; D005727:Ganglia, Spinal / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism*; D011554:Pseudopodia / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism
chemical_list: D000199:Actins; D009479:Neuropeptides; C053386:drebrins; D020932:Nerve Growth Factor
keywords: NGF; interstitial; sprouting