Mutual antagonism between signals secreted by adjacent wingless and engrailed cells leads to specification of complementary regions of the Drosophila parasegment.
Specialized groups of cells known as organizers govern the establishment of cell type diversity across cellular fields. Segmental patterning within the Drosophila embryonic epidermis is one paradigm for organizer function. Here cells differentiate into smooth cuticle or distinct denticle types. At parasegment boundaries, cells expressing Wingless confront cells co-expressing Engrailed and Hedgehog. While Wingless is essential for smooth cell fates, the signals that establish denticle diversity are unknown. We show that wg mutants have residual mirror-symmetric pattern that is due to an Engrailed-dependent signal specifying anterior denticle fates. The Engrailed-dependent signal acts unidirectionally and Wg activity imposes this asymmetry. Reciprocally, the Engrailed/Hedgehog interface imposes asymmetry on Wg signaling. Thus, a bipartite organizer, with each signal acting essentially unidirectionally, specifies segmental pattern.
Gritzan
U
U
Cell & Developmental Biology, University of Pennsylvania Medical School, Philadelphia, PA 19104, USA.
Hatini
V
V
DiNardo
S
S
D000818:Animals; D019521:Body Patterning / Q000235:genetics; D002135:Calcium-Binding Proteins; D002454:Cell Differentiation; D004330:Drosophila / Q000196:embryology* / Q000235:genetics; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian; D004627:Embryonic Induction; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D000072099:Serrate-Jagged Proteins; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D051155:Wnt1 Protein
D002135:Calcium-Binding Proteins; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; C081481:Rho protein, Drosophila; C000606278:Ser protein, Drosophila; D000072099:Serrate-Jagged Proteins; C472498:Stet protein, Drosophila; D014157:Transcription Factors; D051155:Wnt1 Protein; C074622:wg protein, Drosophila; C077245:hh protein, Drosophila