ABSTRACT
Nitric oxide gas acts as a short-range signaling molecule in a vast array of important physiological processes, many of which include major changes in gene expression. How these genomic responses are induced, however, is poorly understood. Here, using genetic and chemical manipulations, we show that nitric oxide is produced in the Drosophila prothoracic gland, where it acts via the nuclear receptor ecdysone-induced protein 75 (E75), reversing its ability to interfere with its heterodimer partner, Drosophila hormone receptor 3 (DHR3). Manipulation of these interactions leads to gross alterations in feeding behavior, fat deposition, and developmental timing. These neuroendocrine interactions and consequences appear to be conserved in vertebrates.
Subject(s)
DNA-Binding Proteins/metabolism , Drosophila Proteins/metabolism , Drosophila melanogaster/physiology , Nitric Oxide/metabolism , Transcription Factors/metabolism , Animals , DNA-Binding Proteins/genetics , DNA-Binding Proteins/pharmacology , Drosophila Proteins/genetics , Drosophila Proteins/pharmacology , Drosophila melanogaster/drug effects , Drosophila melanogaster/genetics , Drosophila melanogaster/growth & development , Drosophila melanogaster/metabolism , Ecdysone/pharmacology , Feeding Behavior/physiology , Free Radical Scavengers/pharmacology , Gene Expression Profiling , Gene Expression Regulation, Developmental/drug effects , Gene Knockdown Techniques , Larva , Lipid Metabolism , Metamorphosis, Biological/genetics , Metamorphosis, Biological/physiology , Nitric Oxide/pharmacology , RNA Interference , Receptors, Cytoplasmic and Nuclear/metabolism , Receptors, Steroid/metabolism , Transcription Factors/genetics , Transcription Factors/pharmacologyABSTRACT
Ubiquitin-mediated proteolysis regulates the steady-state abundance of proteins and controls cellular homoeostasis by abrupt elimination of key effector proteins. A multienzyme system targets proteins for destruction through the covalent attachment of a multiubiquitin chain. The specificity and timing of protein ubiquitination is controlled by ubiquitin ligases, such as the Skp1-Cullin-F box protein complex. Cullins are major components of SCF complexes, and have been implicated in degradation of key regulatory molecules including Cyclin E, beta-catenin and Cubitus interruptus. Here, we describe the genetic identification and molecular characterisation of the Drosophila Cullin-3 homologue. Perturbation of Cullin-3 function has pleiotropic effects during development, including defects in external sensory organ development, pattern formation and cell growth and survival. Loss or overexpression of Cullin-3 causes an increase or decrease, respectively, in external sensory organ formation, implicating Cullin-3 function in regulating the commitment of cells to the neural fate. We also find that Cullin-3 function modulates Hedgehog signalling by regulating the stability of full-length Cubitus interruptus (Ci155). Loss of Cullin-3 function in eye discs but not other imaginal discs promotes cell-autonomous accumulation of Ci155. Conversely, overexpression of Cullin-3 results in a cell-autonomous stabilisation of Ci155 in wing, haltere and leg, but not eye, imaginal discs suggesting tissue-specific regulation of Cullin-3 function. The diverse nature of Cullin-3 phenotypes highlights the importance of targeted proteolysis during Drosophila development.
