Induction of the early-late Ddc gene during Drosophila metamorphosis by the ecdysone receptor

Li Chen, Christian Reece, Sandra L. O'Keefe, Gregory W.L. Hawryluk, Monica M. Engstrom, Ross B. Hodgetts

Research output: Contribution to journalArticle

Abstract

During Drosophila metamorphosis, the 'early-late' genes constitute a unique class regulated by the steroid hormone 20-hydroxyecdysone. Their induction is comprised of both a primary and a secondary response to ecdysone. Previous work has suggested that the epidermal expression of the dopa decarboxylase gene (Ddc) is likely that of a typical early-late gene. Accumulation of the Ddc transcript is rapidly initiated in the absence of protein synthesis, which implies that the ecdysone receptor plays a direct role in induction. However, full Ddc expression requires the participation of one of the transcription factors encoded by the Broad-Complex. In this paper, we characterize an ecdysone response element (EcRE) that contributes to the primary response. Using gel mobility shift assays and transgenic assays, we identified a single functional EcRE, located at position -97 to -83bp relative to the transcription initiation site. This is the first report of an EcRE associated with an early-late gene in Drosophila. Competition experiments indicated that the affinity of the Ddc EcRE for the ecdysone receptor complex was at least four-fold less than that of the canonical EcRE of the hsp27 gene. Using in vitro mutagenesis, we determined that the reduced affinity of the EcRE resided at two positions where the nucleotides differed from those found in the canonical sequence. The ecdysone receptor, acting through this EcRE, releases Ddc from a silencing mechanism, whose cis-acting domain we have mapped to the 5′-upstream region between -2067 and -1427bp. Deletion of this repressive element resulted in precocious expression of Ddc in both epidermis and imaginal discs. Thus, epidermal Ddc induction at pupariation is under the control of an extended genomic region that contains both positive and negative regulatory elements.

Original languageEnglish (US)
Pages (from-to)95-107
Number of pages13
JournalMechanisms of Development
Volume114
Issue number1-2
DOIs
StatePublished - May 13 2002

Keywords

  • Dopa decarboxylase
  • Drosophila melanogaster
  • Early-late genes
  • Ecdysone
  • Steroid hormone receptor

ASJC Scopus subject areas

  • Embryology
  • Developmental Biology

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  • Cite this

    Chen, L., Reece, C., O'Keefe, S. L., Hawryluk, G. W. L., Engstrom, M. M., & Hodgetts, R. B. (2002). Induction of the early-late Ddc gene during Drosophila metamorphosis by the ecdysone receptor. Mechanisms of Development, 114(1-2), 95-107. https://doi.org/10.1016/S0925-4773(02)00064-3