Essential roles for the Dhr78 orphan nuclear receptor during molting of the Drosophila tracheal system

Insect Biochem Mol Biol. 2003 Dec;33(12):1201-9. doi: 10.1016/j.ibmb.2003.06.011.


The Drosophila Dhr78 orphan nuclear receptor has been proposed to play a role in molting of the tracheal cuticle and regulate gene expression during the third larval instar, possibly in response to a novel systemic hormonal signal. Here, we show that there are no essential maternal functions for Dhr78 during development, and that mutants missing both maternal and zygotic Dhr78 function die primarily during second and third instar larval development. We show that defects in the tracheal system can be observed as early as the first instar, manifested as regions of fluid in the dorsal tracheal trunks. In addition, Dhr78 mutant tracheae show a highly penetrant defect in gas filling at the first-to-second instar larval molt. Dhr78 expression in only the tracheal system is sufficient to rescue the lethality of Dhr78 mutants, and selective inactivation of Dhr78 function in the tracheae by targeted RNAi is sufficient to result in tracheal defects. Finally, we see no evidence for widespread activation of the Dhr78 ligand binding domain in third instar larvae using the GAL4-LBD system, arguing against a systemic hormone for the receptor at this stage in development. Taken together, our results indicate that Dhr78 exerts its essential functions during molting of the tracheal cuticle in Drosophila.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromosomes
  • Clone Cells
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / physiology*
  • Drosophila / embryology
  • Drosophila / genetics
  • Drosophila / physiology*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / physiology*
  • Female
  • Genes, Insect / genetics
  • Genes, Lethal / genetics
  • Germ-Line Mutation
  • Larva
  • Molting / genetics
  • Molting / physiology*
  • Mutation
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / physiology*
  • Tissue Distribution
  • Trachea / physiology*
  • Zygote / physiology


  • DNA-Binding Proteins
  • Drosophila Proteins
  • Hr78 protein, Drosophila
  • Receptors, Cytoplasmic and Nuclear