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1 Departments of Developmental Biology, Genetics, and Bioengineering, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, 94305, USA; 2 Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, 94305, USA
Growth and body size are regulated by the CNS, integrating the genetic developmental program with assessments of an animals 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.
[Keywords: Nucleostemin; serotonin; insulin; neurons; growth; size]
Received March 6, 2008; revised version accepted May 23, 2008.
E-MAIL mscott{at}stanford.edu; FAX (650) 725-2952.
Supplemental material is available at http://www.genesdev.org.
Article is online at http://www.genesdev.org/cgi/doi/10.1101/gad.1670508.
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Genes & Dev. 2008 22: 1851-1855.
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A.-F. Ruaud and C. S. Thummel Serotonin and insulin signaling team up to control growth in Drosophila Genes & Dev., July 15, 2008; 22(14): 1851 - 1855. [Abstract] [Full Text] [PDF] |
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