Phenotypic analysis of EcR-A mutants suggests that EcR isoforms have unique functions during Drosophila development

Melissa B Davis, Ginger E. Carney, Anne E. Robertson, Michael Bender

Research output: Contribution to journalArticle

70 Citations (Scopus)

Abstract

The steroid hormone ecdysone triggers transitions between developmental stages in Drosophila by acting through a heterodimer consisting of the EcR and USP nuclear receptors. The EcR gene encodes three protein isoforms (EcR-A, EcR-B1, and EcR-B2) that have unique amino termini but that contain a common carboxy-terminal region including DNA-binding and ligand-binding domains. EcR-A and EcR-B1 are expressed in a spatially complementary pattern at the onset of metamorphosis, suggesting that specific responses to ecdysone involve distinct EcR isoforms. Here, we describe phenotypes of EcR-A specific deletion mutants isolated using transposon mutagenesis. Western blot analysis shows that each of these mutants completely lacks EcR-A protein, while the EcR-B1 protein is still present. The EcR112 strain has a deletion of EcR-A specific non-coding and regulatory sequences but retains the coding exons, while the EcR139 strain has a deletion of EcR-A specific protein coding exons but retains the regulatory region. In these mutants, the developmental progression of most internal tissues that normally express EcR-B1 is unaffected by the lack of EcR-A. Surprisingly, however, we found that one larval tissue, the salivary gland, fails to degenerate even though EcR-B1 is the predominant isoform. This result may indicate that the low levels of EcR-A in this tissue are in fact required. We identified yet another type of mutation, the EcR 94 deletion, that removes the EcR-A specific protein coding exons as well as the introns between the EcR-A and EcR-B transcription start sites. This deletion places the EcR-A regulatory region adjacent to the EcR-B transcription start site. While EcR112 and EcR139 mutant animals die during mid and late pupal development, respectively, EcR94 mutants arrest prior to pupariation. EcR-A mutant phenotypes and lethal phases differ from those of EcR-B mutants, suggesting that the EcR isoforms have distinct developmental functions.

Original languageEnglish (US)
Pages (from-to)385-396
Number of pages12
JournalDevelopmental Biology
Volume282
Issue number2
DOIs
StatePublished - Jun 15 2005
Externally publishedYes

Fingerprint

Drosophila
Protein Isoforms
Ecdysone
Exons
Nucleic Acid Regulatory Sequences
Transcription Initiation Site
Proteins
Phenotype
Cytoplasmic and Nuclear Receptors
Salivary Glands
Mutagenesis
Introns
Western Blotting
Steroids
Hormones
Ligands
Mutation
DNA
Genes

Keywords

  • Drosophila
  • EcR-A
  • Ecdysone receptor
  • Metamorphosis

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

Cite this

Phenotypic analysis of EcR-A mutants suggests that EcR isoforms have unique functions during Drosophila development. / Davis, Melissa B; Carney, Ginger E.; Robertson, Anne E.; Bender, Michael.

In: Developmental Biology, Vol. 282, No. 2, 15.06.2005, p. 385-396.

Research output: Contribution to journalArticle

Davis, Melissa B ; Carney, Ginger E. ; Robertson, Anne E. ; Bender, Michael. / Phenotypic analysis of EcR-A mutants suggests that EcR isoforms have unique functions during Drosophila development. In: Developmental Biology. 2005 ; Vol. 282, No. 2. pp. 385-396.
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