title: C. elegans Punctin specifies cholinergic versus GABAergic identity of postsynaptic domains.
abstract: Because most neurons receive thousands of synaptic inputs, the neuronal membrane is a mosaic of specialized microdomains where neurotransmitter receptors cluster in register with the corresponding presynaptic neurotransmitter release sites. In many cases the coordinated differentiation of presynaptic and postsynaptic domains implicates trans-synaptic interactions between membrane-associated proteins such as neurexins and neuroligins. The Caenorhabditis elegans neuromuscular junction (NMJ) provides a genetically tractable system in which to analyse the segregation of neurotransmitter receptors, because muscle cells receive excitatory innervation from cholinergic neurons and inhibitory innervation from GABAergic neurons. Here we show that Ce-Punctin/madd-4 (ref. 5), the C. elegans orthologue of mammalian punctin-1 and punctin-2, encodes neurally secreted isoforms that specify the excitatory or inhibitory identity of postsynaptic NMJ domains. These proteins belong to the ADAMTS (a disintegrin and metalloprotease with thrombospondin repeats)-like family, a class of extracellular matrix proteins related to the ADAM proteases but devoid of proteolytic activity. Ce-Punctin deletion causes the redistribution of synaptic acetylcholine and GABAA (γ-aminobutyric acid type A) receptors into extrasynaptic clusters, whereas neuronal presynaptic boutons remain unaltered. Alternative promoters generate different Ce-Punctin isoforms with distinct functions. A short isoform is expressed by cholinergic and GABAergic motoneurons and localizes to excitatory and inhibitory NMJs, whereas long isoforms are expressed exclusively by cholinergic motoneurons and are confined to cholinergic NMJs. The differential expression of these isoforms controls the congruence between presynaptic and postsynaptic domains: specific disruption of the short isoform relocalizes GABAA receptors from GABAergic to cholinergic synapses, whereas expression of a long isoform in GABAergic neurons recruits acetylcholine receptors to GABAergic NMJs. These results identify Ce-Punctin as a previously unknown synaptic organizer and show that presynaptic and postsynaptic domain identities can be genetically uncoupled in vivo. Because human punctin-2 was identified as a candidate gene for schizophrenia, ADAMTS-like proteins may also control synapse organization in the mammalian central nervous system.
authors.affiliation: 1] Institute of Biology, École Normale Supérieure, 75005 Paris, France [2] University Claude Bernard Lyon 1, CGphiMC UMR CNRS 5534, 69622 Villeurbanne, France [3].
authors.forename: Bérangère
authors.initials: B
authors.lastname: Pinan-Lucarré
authors.affiliation: 1] Institute of Biology, École Normale Supérieure, 75005 Paris, France [2] University Claude Bernard Lyon 1, CGphiMC UMR CNRS 5534, 69622 Villeurbanne, France [3].
authors.forename: Haijun
authors.initials: H
authors.lastname: Tu
authors.affiliation: 1] Institute of Biology, École Normale Supérieure, 75005 Paris, France [2] University Claude Bernard Lyon 1, CGphiMC UMR CNRS 5534, 69622 Villeurbanne, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Pierron
authors.affiliation: Institute of Biology, École Normale Supérieure, 75005 Paris, France.
authors.forename: Pablo Ibáñez
authors.initials: PI
authors.lastname: Cruceyra
authors.affiliation: 1] Institute of Biology, École Normale Supérieure, 75005 Paris, France [2] University Claude Bernard Lyon 1, CGphiMC UMR CNRS 5534, 69622 Villeurbanne, France.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhan
authors.affiliation: 1] Institute of Biology, École Normale Supérieure, 75005 Paris, France [2] University of Würzburg, Biocenter, Division of Electron Microscopy, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Stigloher
authors.affiliation: Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Richmond
authors.affiliation: 1] Institute of Biology, École Normale Supérieure, 75005 Paris, France [2] University Claude Bernard Lyon 1, CGphiMC UMR CNRS 5534, 69622 Villeurbanne, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Bessereau
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism; D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000378:metabolism*; D059329:Cholinergic Neurons / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D059330:GABAergic Neurons / Q000378:metabolism*; D009046:Motor Neurons / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism*; D009469:Neuromuscular Junction; D057907:Post-Synaptic Density / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D016326:Extracellular Matrix Proteins; C568399:MADD-4 protein, C elegans; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D011950:Receptors, Cholinergic; D011963:Receptors, GABA-A; D051722:ADAM Proteins; D000109:Acetylcholine