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Mol Cell Neurosci. 2014 Jul;61:241-54. doi: 10.1016/j.mcn.2014.07.005. Epub 2014 Jul 24.

Postsynaptic actin regulates active zone spacing and glutamate receptor apposition at the Drosophila neuromuscular junction.

Author information

1
The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
2
The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; The Department of Oral Pathology, School of Dentistry, Pusan National University, Republic of Korea.
3
Department of Developmental Biology, University of Saarland, Homburg, Saar, Germany.
4
Howard Hughes Medical Institute (HHMI), Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States.
5
Howard Hughes Medical Institute (HHMI), Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States; Department of Physics, Harvard University, Cambridge, MA 02138, United States.
6
The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, United States. Electronic address: troy@mit.edu.

Abstract

Synaptic communication requires precise alignment of presynaptic active zones with postsynaptic receptors to enable rapid and efficient neurotransmitter release. How transsynaptic signaling between connected partners organizes this synaptic apparatus is poorly understood. To further define the mechanisms that mediate synapse assembly, we carried out a chemical mutagenesis screen in Drosophila to identify mutants defective in the alignment of active zones with postsynaptic glutamate receptor fields at the larval neuromuscular junction. From this screen we identified a mutation in Actin 57B that disrupted synaptic morphology and presynaptic active zone organization. Actin 57B, one of six actin genes in Drosophila, is expressed within the postsynaptic bodywall musculature. The isolated allele, act(E84K), harbors a point mutation in a highly conserved glutamate residue in subdomain 1 that binds members of the Calponin Homology protein family, including spectrin. Homozygous act(E84K) mutants show impaired alignment and spacing of presynaptic active zones, as well as defects in apposition of active zones to postsynaptic glutamate receptor fields. act(E84K) mutants have disrupted postsynaptic actin networks surrounding presynaptic boutons, with the formation of aberrant actin swirls previously observed following disruption of postsynaptic spectrin. Consistent with a disruption of the postsynaptic actin cytoskeleton, spectrin, adducin and the PSD-95 homolog Discs-Large are all mislocalized in act(E84K) mutants. Genetic interactions between act(E84K) and neurexin mutants suggest that the postsynaptic actin cytoskeleton may function together with the Neurexin-Neuroligin transsynaptic signaling complex to mediate normal synapse development and presynaptic active zone organization.

KEYWORDS:

Actin; Cytoskeleton; NMJ; Neurexin; Spectrin; Synapse

PMID:
25066865
PMCID:
PMC4134997
DOI:
10.1016/j.mcn.2014.07.005
[Indexed for MEDLINE]
Free PMC Article

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