title: Neuropeptide-Driven Cross-Modal Plasticity following Sensory Loss in Caenorhabditis elegans.
abstract: Sensory loss induces cross-modal plasticity, often resulting in altered performance in remaining sensory modalities. Whereas much is known about the macroscopic mechanisms underlying cross-modal plasticity, only scant information exists about its cellular and molecular underpinnings. We found that Caenorhabditis elegans nematodes deprived of a sense of body touch exhibit various changes in behavior, associated with other unimpaired senses. We focused on one such behavioral alteration, enhanced odor sensation, and sought to reveal the neuronal and molecular mechanisms that translate mechanosensory loss into improved olfactory acuity. To this end, we analyzed in mechanosensory mutants food-dependent locomotion patterns that are associated with olfactory responses and found changes that are consistent with enhanced olfaction. The altered locomotion could be reversed in adults by optogenetic stimulation of the touch receptor (mechanosensory) neurons. Furthermore, we revealed that the enhanced odor response is related to a strengthening of inhibitory AWC→AIY synaptic transmission in the olfactory circuit. Consistently, inserting in this circuit an engineered electrical synapse that diminishes AWC inhibition of AIY counteracted the locomotion changes in touch-deficient mutants. We found that this cross-modal signaling between the mechanosensory and olfactory circuits is mediated by neuropeptides, one of which we identified as FLP-20. Our results indicate that under normal function, ongoing touch receptor neuron activation evokes FLP-20 release, suppressing synaptic communication and thus dampening odor sensation. In contrast, in the absence of mechanosensory input, FLP-20 signaling is reduced, synaptic suppression is released, and this enables enhanced olfactory acuity; these changes are long lasting and do not represent ongoing modulation, as revealed by optogenetic experiments. Our work adds to a growing literature on the roles of neuropeptides in cross-modal signaling, by showing how activity-dependent neuropeptide signaling leads to specific cross-modal plastic changes in neural circuit connectivity, enhancing sensory performance.
authors.affiliation: Department of Medical Neurobiology, Hadassah Medical School, Hebrew University of Jerusalem, Jerusalem, Israel.|Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.|Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America.
authors.forename: Ithai
authors.initials: I
authors.lastname: Rabinowitch
authors.affiliation: Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.|ULB Neuroscience Institute, Université Libre de Bruxelles, Bruxelles, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Laurent
authors.affiliation: Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
authors.forename: Buyun
authors.initials: B
authors.lastname: Zhao
authors.affiliation: Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
authors.forename: Denise
authors.initials: D
authors.lastname: Walker
authors.affiliation: Functional Genomics and Proteomics, KU Leuven, Leuven, Belgium.
authors.forename: Isabel
authors.initials: I
authors.lastname: Beets
authors.affiliation: Functional Genomics and Proteomics, KU Leuven, Leuven, Belgium.
authors.forename: Liliane
authors.initials: L
authors.lastname: Schoofs
authors.affiliation: Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America.
authors.forename: Jihong
authors.initials: J
authors.lastname: Bai
authors.affiliation: Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
authors.forename: William R
authors.initials: WR
authors.lastname: Schafer
authors.affiliation: Department of Medical Neurobiology, Hadassah Medical School, Hebrew University of Jerusalem, Jerusalem, Israel.
authors.forename: Millet
authors.initials: M
authors.lastname: Treinin
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000502:physiology*; D002628:Chemoreceptor Cells / Q000502:physiology*; D008124:Locomotion; D008465:Mechanoreceptors / Q000378:metabolism*; D009473:Neuronal Plasticity; D009479:Neuropeptides / Q000502:physiology*; D012903:Smell; D009435:Synaptic Transmission
chemical_list: D009479:Neuropeptides