title: lin-14 regulates the timing of synaptic remodelling in Caenorhabditis elegans.
abstract: In the nematode Caenorhabditis elegans six GABAergic motor neurons, known as DDs, remodel their patterns of synaptic connectivity during larval development. DD remodelling involves a complete reversal of the direction of information flow within nerve processes without marked changes in process morphology. We used a marker localized in vivo to DD presynaptic zones to analyse how the timing of DD remodelling is controlled. In wild-type animals, DDs remodel their synaptic outputs within a 3-5-hour period at the end of the first larval stage. We show that the heterochronic gene lin-14, which controls the timing of stage-specific cell lineages, regulates the timing of DD synaptic output remodelling. In lin-14 loss-of-function mutants, DDs remodel precociously. The degree of precocious remodelling is correlated with the level of lin-14 activity. Expression of lin-14(+) in the DDs of lin-14-null mutants rescues the precocious remodelling, indicating that lin-14 can act cell-autonomously. Consistent with this hypothesis, LIN-14 protein levels decrease in the DDs before remodelling. Our observations reveal a role of heterochronic genes in non-dividing cells, and provide an example of cell-autonomous respecification of neuronal connectivity.
authors.affiliation: Department of Biology, Sinsheimer Laboratories, University of California, Santa Cruz, 95064, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Hallam
authors.forename: Y
authors.initials: Y
authors.lastname: Jin
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins; D016764:Cell Polarity; D005968:Glutamate Decarboxylase / Q000235:genetics; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D009687:Nuclear Proteins; D013569:Synapses / Q000502:physiology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; C102669:LIN-14 protein, C elegans; D008565:Membrane Proteins; D009687:Nuclear Proteins; D005968:Glutamate Decarboxylase