title: Ecdysone signaling opposes epidermal growth factor signaling in regulating cyst differentiation in the male gonad of Drosophila melanogaster.
abstract: The development of stem cell daughters into the differentiated state normally requires a cascade of proliferation and differentiation steps that are typically regulated by external signals. The germline cells of most animals, in specific, are associated with somatic support cells and depend on them for normal development. In the male gonad of Drosophila melanogaster, germline cells are completely enclosed by cytoplasmic extensions of somatic cyst cells, and these cysts form a functional unit. Signaling from the germline to the cyst cells via the Epidermal Growth Factor Receptor (EGFR) is required for germline enclosure and has been proposed to provide a temporal signature promoting early steps of differentiation. A temperature-sensitive allele of the EGFR ligand Spitz (Spi) provides a powerful tool for probing the function of the EGRF pathway in this context and for identifying other pathways regulating cyst differentiation via genetic interaction studies. Using this tool, we show that signaling via the Ecdysone Receptor (EcR), a known regulator of developmental timing during larval and pupal development, opposes EGF signaling in testes. In spi mutant animals, reducing either Ecdysone synthesis or the expression of Ecdysone signal transducers or targets in the cyst cells resulted in a rescue of cyst formation and cyst differentiation. Despite of this striking effect in the spi mutant background and the expression of EcR signaling components within the cyst cells, activity of the EcR pathway appears to be dispensable in a wildtype background. We propose that EcR signaling modulates the effects of EGFR signaling by promoting an undifferentiated state in early stage cyst cells.
authors.affiliation: University of Georgia, Department of Cellular Biology, Athens, GA, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Qian
authors.affiliation: University of Melbourne, Department of Anatomy and Neuroscience, Melbourne, Australia.
authors.forename: Nicole
authors.initials: N
authors.lastname: Dominado
authors.affiliation: University of Georgia, Department of Cellular Biology, Athens, GA, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Zoller
authors.affiliation: University of Georgia, Department of Cellular Biology, Athens, GA, USA.
authors.forename: Chun
authors.initials: C
authors.lastname: Ng
authors.affiliation: University of Georgia, Department of Cellular Biology, Athens, GA, USA.
authors.forename: Karl
authors.initials: K
authors.lastname: Kudyba
authors.affiliation: University of Melbourne, Department of Anatomy and Neuroscience, Melbourne, Australia.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Siddall
authors.affiliation: University of Melbourne, Department of Anatomy and Neuroscience, Melbourne, Australia.
authors.forename: Gary R
authors.initials: GR
authors.lastname: Hime
authors.affiliation: University of Georgia, Department of Cellular Biology, Athens, GA, USA.
authors.forename: Cordula
authors.initials: C
authors.lastname: Schulz
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D017931:DNA Primers / Q000235:genetics; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000196:embryology*; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D011987:Receptors, Steroid / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D013737:Testis / Q000166:cytology*
chemical_list: D017931:DNA Primers; D029721:Drosophila Proteins; D008565:Membrane Proteins; D011987:Receptors, Steroid; C055469:ecdysone receptor; C076026:spi protein, Drosophila; D004815:Epidermal Growth Factor; D066246:ErbB Receptors
keywords: Cyst cells; Differentiation; Drosophila; EGF; EcR; Testes