Drosophila growth cones: a genetically tractable platform for the analysis of axonal growth dynamics.
The formation of neuronal networks, during development and regeneration, requires outgrowth of axons along reproducible paths toward their appropriate postsynaptic target cells. Axonal extension occurs at growth cones (GCs) at the tips of axons. GC advance and navigation requires the activity of their cytoskeletal networks, comprising filamentous actin (F-actin) in lamellipodia and filopodia as well as dynamic microtubules (MTs) emanating from bundles of the axonal core. The molecular mechanisms governing these two cytoskeletal networks, their cross-talk, and their response to extracellular signaling cues are only partially understood, hindering our conceptual understanding of how regulated changes in GC behavior are controlled. Here, we introduce Drosophila GCs as a suitable model to address these mechanisms. Morphological and cytoskeletal readouts of Drosophila GCs are similar to those of other models, including mammals, as demonstrated here for MT and F-actin dynamics, axonal growth rates, filopodial structure and motility, organizational principles of MT networks, and subcellular marker localization. Therefore, we expect fundamental insights gained in Drosophila to be translatable into vertebrate biology. The advantage of the Drosophila model over others is its enormous amenability to combinatorial genetics as a powerful strategy to address the complexity of regulatory networks governing axonal growth. Thus, using pharmacological and genetic manipulations, we demonstrate a role of the actin cytoskeleton in a specific form of MT organization (loop formation), known to regulate GC pausing behavior. We demonstrate these events to be mediated by the actin-MT linking factor Short stop, thus identifying an essential molecular player in this context.
Sánchez-Soriano
Natalia
N
Faculty of Life Sciences, Wellcome Trust Centre for Cell-Matrix Research, Manchester M13 9PT, United Kingdom.
Gonçalves-Pimentel
Catarina
C
Beaven
Robin
R
Haessler
Ulrike
U
Ofner-Ziegenfuss
Lisa
L
Ballestrem
Christoph
C
Prokop
Andreas
A
D000199:Actins / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000502:physiology*; D049108:Cell Enlargement; D002465:Cell Movement / Q000235:genetics* / Q000502:physiology*; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D020439:Growth Cones / Q000502:physiology*; D007150:Immunohistochemistry; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008870:Microtubules / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology; D011554:Pseudopodia / Q000502:physiology; D013997:Time Factors
D000199:Actins; D029721:Drosophila Proteins; D008840:Microfilament Proteins; C450828:shot protein, Drosophila