Drosophila KDEL receptor function in the embryonic salivary gland and epidermis

PLoS One. 2013 Oct 18;8(10):e77618. doi: 10.1371/journal.pone.0077618. eCollection 2013.


Core components of the secretory pathway have largely been identified and studied in single cell systems such as the budding yeast S. cerevisiae or in mammalian tissue culture. These studies provide details on the molecular functions of the secretory machinery; they fail, however, to provide insight into the role of these proteins in the context of specialized organs of higher eukaryotes. Here, we identify and characterize the first loss-of-function mutations in a KDEL receptor gene from higher eukaryotes. Transcripts from the Drosophila KDEL receptor gene KdelR - formerly known as dmErd2 - are provided maternally and, at later stages, are at elevated levels in several embryonic cell types, including the salivary gland secretory cells, the fat body and the epidermis. We show that, unlike Saccharomyces cerevisiae Erd2 mutants, which are viable, KdelR mutations are early larval lethal, with homozygous mutant animals dying as first instar larvae. KdelR mutants have larval cuticle defects similar to those observed with loss-of-function mutations in other core secretory pathway genes and with mutations in CrebA, which encodes a bZip transcription factor that coordinately upregulates secretory pathway component genes in specialized secretory cell types. Using the salivary gland, we demonstrate a requirement for KdelR in maintaining the ER pool of a subset of soluble resident ER proteins. These studies underscore the utility of the Drosophila salivary gland as a unique system for studying the molecular machinery of the secretory pathway in vivo in a complex eukaryote.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism
  • Cyclic AMP Response Element-Binding Protein A / genetics
  • Cyclic AMP Response Element-Binding Protein A / metabolism
  • Drosophila / embryology
  • Drosophila / genetics*
  • Drosophila / metabolism*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism
  • Epidermis / embryology
  • Epidermis / metabolism*
  • Genes, Insect / genetics
  • Mutation / genetics
  • Receptors, Peptide / genetics*
  • Receptors, Peptide / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Salivary Glands / embryology
  • Salivary Glands / metabolism*
  • Secretory Pathway / genetics
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • CrebA protein, Drosophila
  • Cyclic AMP Response Element-Binding Protein A
  • Drosophila Proteins
  • KDEL receptor
  • Receptors, Peptide
  • Transcription Factors