title: Drosophila pacemaker neurons require g protein signaling and GABAergic inputs to generate twenty-four hour behavioral rhythms.
abstract: Intercellular signaling is important for accurate circadian rhythms. In Drosophila, the small ventral lateral neurons (s-LN(v)s) are the dominant pacemaker neurons and set the pace of most other clock neurons in constant darkness. Here we show that two distinct G protein signaling pathways are required in LN(v)s for 24 hr rhythms. Reducing signaling in LN(v)s via the G alpha subunit Gs, which signals via cAMP, or via the G alpha subunit Go, which we show signals via Phospholipase 21c, lengthens the period of behavioral rhythms. In contrast, constitutive Gs or Go signaling makes most flies arrhythmic. Using dissociated LN(v)s in culture, we found that Go and the metabotropic GABA(B)-R3 receptor are required for the inhibitory effects of GABA on LN(v)s and that reduced GABA(B)-R3 expression in vivo lengthens period. Although no clock neurons produce GABA, hyperexciting GABAergic neurons disrupts behavioral rhythms and s-LN(v) molecular clocks. Therefore, s-LN(v)s require GABAergic inputs for 24 hr rhythms.
authors.affiliation: Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA.
authors.forename: David
authors.initials: D
authors.lastname: Dahdal
authors.forename: David C
authors.initials: DC
authors.lastname: Reeves
authors.forename: Marc
authors.initials: M
authors.lastname: Ruben
authors.forename: Myles H
authors.initials: MH
authors.lastname: Akabas
authors.forename: Justin
authors.initials: J
authors.lastname: Blau
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D004330:Drosophila / Q000166:cytology / Q000502:physiology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D018080:Receptors, GABA-B; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs