Isolation of a functional ecdysteroid receptor homologue from the ixodid tick Amblyomma americanum (L.)

Xiaoping Guo, Margaret A. Harmon, Vincent Laudet, David J. Mangelsdorf, Melanie J. Palmer

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

Ecdysteroids are assumed to be the major steroid hormones in arthropods. However, with the exception of insects and crustaceans, very little is known about ecdysteroid action in other arthropods. To determine if ecdysteriods play a functional role in the ixodid tick, Amblyomma americanum (L.), we isolated cDNAs encoding three presumed ecdysteroid receptor isoforms (AamEcRA1, AamEcRA2, and AamEcRA3) that have common DNA and ligand binding domains linked to distinct amino termini. The DNA and ligand binding domains share an average of 86 and 64% identity, respectively with DNA and ligand binding domains from insect EcR proteins. The amino termini are highly divergent and the AamEcRs lack the 'F' domain found in the insect EcRs. Analysis of AamEcR cDNAs show that processing of the AamEcR gene is complex, producing multiple transcripts with unique 5' and 3' termini as well as splicing variants with incomplete open reading frames. AamEcR mRNA profiles in whole animals and isolated tissues are consistent with complex regulation of AamEcR expression. We also examined the ability of AamEcRA1, when paired with an AamRXR, to activate transcription of an ecdysone response element containing reporter, and demonstrate that the AamEcR gene encodes a functional ecdysteroid receptor.

Original languageEnglish (US)
Pages (from-to)945-962
Number of pages18
JournalInsect Biochemistry and Molecular Biology
Volume27
Issue number11
DOIs
Publication statusPublished - Nov 1998

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Keywords

  • Arnblyomma americanum
  • Ecdysone
  • Ecdysteroid receptor
  • Tick

ASJC Scopus subject areas

  • Insect Science
  • Biochemistry

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