A presynaptic role of microtubule-associated protein 1/Futsch in Drosophila: regulation of active zone number and neurotransmitter release

• Published in: The Journal of neuroscience Vol. 34; no. 20; pp. 6759 - 6771
• Main Authors: Lepicard, Simon, Franco, Bénédicte, de Bock, Frédéric, Parmentier, Marie-Laure
• Format: Journal Article
• Language: English
• Published: United States Society for Neuroscience 14-05-2014
• Subjects: Animals; Animals, Genetically Modified; Axonal Transport - genetics; Cytoskeleton - genetics; Cytoskeleton - metabolism; Drosophila; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Glutamic Acid - metabolism; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - metabolism; Microtubules - genetics; Microtubules - metabolism; Neuromuscular Junction - genetics; Neuromuscular Junction - metabolism; Presynaptic Terminals - metabolism; Synaptic Transmission - physiology; synaptic release; microtubule-associated protein; microtubules; neuromuscular junction; active zone
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/JNEUROSCI.4282-13.2014

Structural microtubule-associated proteins (MAPs), like MAP1, not only control the stability of microtubules, but also interact with postsynaptic proteins in the nervous system. Their presynaptic role has barely been studied. To tackle this question, we used the Drosophila model in which there is only one MAP1 homolog: Futsch, which is expressed at the larval neuromuscular junction, presynaptically only. We show that Futsch regulates neurotransmitter release and active zone density. Importantly, we provide evidence that this role of Futsch is not just the consequence of its microtubule-stabilizing function. Using high-resolution microscopy, we show that Futsch and microtubules are almost systematically present in close proximity to active zones, with Futsch being localized in-between microtubules and active zones. Using proximity ligation assays, we further demonstrate the proximity of Futsch, but not microtubules, to active zone components. Altogether our data are in favor of a model by which Futsch locally stabilizes active zones, by reinforcing their link with the underlying microtubule cytoskeleton.