title: A nucleostemin family GTPase, NS3, acts in serotonergic neurons to regulate insulin signaling and control body size.
abstract: Growth and body size are regulated by the CNS, integrating the genetic developmental program with assessments of an animal's current energy state and environmental conditions. CNS decisions are transmitted to all cells of the animal by insulin/insulin-like signals. The molecular biology of the CNS growth control system has remained, for the most part, elusive. Here we identify NS3, a Drosophila nucleostemin family GTPase, as a powerful regulator of body size. ns3 mutants reach <60% of normal size and have fewer and smaller cells, but exhibit normal body proportions. NS3 does not act cell-autonomously, but instead acts at a distance to control growth. Rescue experiments were performed by expressing wild-type ns3 in many different cells of ns3 mutants. Restoring NS3 to only 106 serotonergic neurons rescued global growth defects. These neurons are closely apposed with those of insulin-producing neurons, suggesting possible communication between the two neuronal systems. In the brains of ns3 mutants, excess serotonin and insulin accumulate, while peripheral insulin pathway activation is low. Peripheral insulin pathway activation rescues the growth defects of ns3 mutants. The findings suggest that NS3 acts in serotonergic neurons to regulate insulin signaling and thus exert global growth control.
authors.affiliation: Departments of Developmental Biology, Genetics, and Bioengineering, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, 94305, USA.
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Kaplan
authors.forename: Gregor
authors.initials: G
authors.lastname: Zimmermann
authors.forename: Kaye
authors.initials: K
authors.lastname: Suyama
authors.forename: Tobias
authors.initials: T
authors.lastname: Meyer
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Scott
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D049628:Body Size / Q000502:physiology*; D002450:Cell Communication; D004330:Drosophila / Q000254:growth & development* / Q000378:metabolism; D029721:Drosophila Proteins / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D015151:Immunoblotting; D017404:In Situ Hybridization, Fluorescence; D007328:Insulin / Q000502:physiology*; D008297:Male; D008845:Microinjections; D009154:Mutation / Q000235:genetics; D009474:Neurons / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology*; D011972:Receptor, Insulin / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012701:Serotonin / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D029721:Drosophila Proteins; D007328:Insulin; D009687:Nuclear Proteins; D012701:Serotonin; D011972:Receptor, Insulin