The Tbx20 homolog Midline represses wingless in conjunction with Groucho during the maintenance of segment polarity.
The regulation of the segment polarity gene wingless is essential for the correct patterning of the Drosophila ectoderm. We have previously shown that the asymmetric activation of wingless downstream of Hedghog-signaling depends on the T-box transcription factors, midline and H15. Hedgehog activates wingless anterior to the Hedgehog domain. midline/H15 are responsible in part for repressing wingless in cells posterior to the Hedgehog expressing cells. Here, we show that Midline binds the Groucho co-repressor directly via the engrailed homology-1 domain and requires an intact engrailed-homology-1 domain to repress wingless. In contrast, the regulation of Serrate, a second target of midline repression, is not dependent on the engrailed-homology-1 domain. Furthermore, we identify a midline responsive region of the wingless cis-regulatory region and show that Midline binds to sequences within this region. Mutating these sequences in transgenic reporter constructs results in ectopic reporter expression in the midline-expression domain, consistent with wingless being a direct target of Midline repression.
Genes and Development Research Group, Alberta Children's Hospital Research Institute, Department of Biochemistry and Molecular Biology, University of Calgary, Canada.
Ann
A
Formaz-Preston
Jae-Ryeon
JR
Ryu
Pia C
PC
Svendsen
William J
WJ
Brook
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019521:Body Patterning / Q000235:genetics / Q000502:physiology; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D000072100:Jagged-1 Protein; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D054730:Protein Interaction Domains and Motifs; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D000072099:Serrate-Jagged Proteins; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051155:Wnt1 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D051792:Basic Helix-Loop-Helix Proteins; D002135:Calcium-Binding Proteins; D017931:DNA Primers; D029721:Drosophila Proteins; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; D012097:Repressor Proteins; D000072099:Serrate-Jagged Proteins; D020825:T-Box Domain Proteins; D051155:Wnt1 Protein; C495572:H15 protein, Drosophila; C000606278:Ser protein, Drosophila; C091023:gro protein, Drosophila; C495571:mid protein, Drosophila; C074622:wg protein, Drosophila