title: Mechanism of Notch Pathway Activation and Its Role in the Regulation of Olfactory Plasticity in Drosophila melanogaster.
abstract: The neural plasticity of sensory systems is being increasingly recognized as playing a role in learning and memory. We have previously shown that Notch, part of an evolutionarily conserved intercellular signaling pathway, is required in adult Drosophila melanogaster olfactory receptor neurons (ORNs) for the structural and functional plasticity of olfactory glomeruli that is induced by chronic odor exposure. In this paper we address how long-term exposure to odor activates Notch and how Notch in conjunction with chronic odor mediates olfactory plasticity. We show that upon chronic odor exposure a non-canonical Notch pathway mediates an increase in the volume of glomeruli by a mechanism that is autonomous to ORNs. In addition to activating a pathway that is autonomous to ORNs, chronic odor exposure also activates the Notch ligand Delta in second order projection neurons (PNs), but this does not appear to require acetylcholine receptor activation in PNs. Delta on PNs then feeds back to activate canonical Notch signaling in ORNs, which restricts the extent of the odor induced increase in glomerular volume. Surprisingly, even though the pathway that mediates the increase in glomerular volume is autonomous to ORNs, nonproductive transsynaptic Delta/Notch interactions that do not activate the canonical pathway can block the increase in volume. In conjunction with chronic odor, the canonical Notch pathway also enhances cholinergic activation of PNs. We present evidence suggesting that this is due to increased acetylcholine release from ORNs. In regulating physiological plasticity, Notch functions solely by the canonical pathway, suggesting that there is no direct connection between morphological and physiological plasticity.
authors.affiliation: Department of Genetics and Development, Columbia University College of Physicians and Surgeons, 701 West 168th Street, New York, New York, United States of America.
authors.forename: Simon
authors.initials: S
authors.lastname: Kidd
authors.affiliation: Department of Genetics and Development, Columbia University College of Physicians and Surgeons, 701 West 168th Street, New York, New York, United States of America.
authors.forename: Toby
authors.initials: T
authors.lastname: Lieber
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000080462:Acyclic Monoterpenes; D000818:Animals; D030801:Animals, Genetically Modified; D002118:Calcium / Q000378:metabolism; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008317:Malpighian Tubules / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D036641:Microscopy, Fluorescence, Multiphoton; D009154:Mutation; D009473:Neuronal Plasticity / Q000502:physiology*; D009812:Odorants; D018034:Olfactory Receptor Neurons / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding; D034622:RNA Interference; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013729:Terpenes / Q000494:pharmacology
chemical_list: D000085:Acetates; D000080462:Acyclic Monoterpenes; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C497759:N protein, Drosophila; D011978:Receptors, Nicotinic; D051880:Receptors, Notch; D013729:Terpenes; C064045:delta protein; C432872:geranyl acetate; D002795:Choline O-Acetyltransferase; D002118:Calcium