Integration of a retrograde signal during synapse formation by glia-secreted TGF-beta ligand
AuthorsFuentes-Medel, Yuly F.
Ashley, James A.
Freeman, Marc R.
UMass Chan AffiliationsGraduate School of Biomedical Sciences, Neuroscience Program
Department of Neurobiology
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AbstractGlial cells are crucial regulators of synapse formation, elimination, and plasticity [1, 2]. In vitro studies have begun to identify glial-derived synaptogenic factors , but neuron-glia signaling events during synapse formation in vivo remain poorly defined. The coordinated development of pre- and postsynaptic compartments at the Drosophila neuromuscular junction (NMJ) depends on a muscle-secreted retrograde signal, the TGF-beta/BMP Glass bottom boat (Gbb) [3, 4]. Muscle-derived Gbb activates the TGF-beta receptors Wishful thinking (Wit) and either Saxophone (Sax) or Thick veins (Tkv) in motor neurons [3, 4]. This induces phosphorylation of Mad (P-Mad) in motor neurons, its translocation into the nucleus with a co-Smad, and activation of transcriptional programs controlling presynaptic bouton growth . Here we show that NMJ glia release the TGF-beta ligand Maverick (Mav), which likely activates the muscle activin-type receptor Punt to potently modulate Gbb-dependent retrograde signaling and synaptic growth. Loss of glial Mav results in strikingly reduced P-Mad at NMJs, decreased Gbb transcription in muscle, and in turn reduced muscle-to-motor neuron retrograde TGF-beta/BMP signaling. We propose that by controlling Gbb release from muscle, glial cells fine tune the ability of motor neurons to extend new synaptic boutons in correlation to muscle growth. Our work identifies a novel glia-derived synaptogenic factor by which glia modulate synapse formation in vivo.
SourceCurr Biol. 2012 Oct 9;22(19):1831-8. doi: 10.1016/j.cub.2012.07.063. Link to article on publisher's site
Permanent Link to this Itemhttp://hdl.handle.net/20.500.14038/37865
First author Yuly Fuentes-Medel is a doctoral student in the Neuroscience Program in the Graduate School of Biomedical Sciences (GSBS) at UMass Medical School.
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