Dpp signalling is a key effector of the wing-body wall subdivision of the Drosophila mesothorax.
During development, the imaginal wing disc of Drosophila is subdivided along the proximal-distal axis into different territories that will give rise to body wall (notum and mesothoracic pleura) and appendage (wing hinge and wing blade). Expression of the Iroquois complex (Iro-C) homeobox genes in the most proximal part of the disc defines the notum, since Iro-C(-) cells within this territory acquire the identity of the adjacent distal region, the wing hinge. Here we analyze how the expression of Iro-C is confined to the notum territory. Neither Wingless signalling, which is essential for wing development, nor Vein-dependent EGFR signalling, which is needed to activate Iro-C, appear to delimit Iro-C expression. We show that a main effector of this confinement is the TGFbeta homolog Decapentaplegic (Dpp), a molecule known to pattern the disc along its anterior-posterior axis. At early second larval instar, the Dpp signalling pathway functions only in the wing and hinge territories, represses Iro-C and confines its expression to the notum territory. Later, Dpp becomes expressed in the most proximal part of the notum and turns off Iro-C in this region. This downregulation is associated with the subdivision of the notum into medial and lateral regions.
Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Cantoblanco, 28049 Madrid, Spain.
Florencia
F
Cavodeassi
Isabel
I
Rodríguez
Juan
J
Modolell
D000818:Animals; D019521:Body Patterning; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D066246:ErbB Receptors / Q000235:genetics / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D017344:Genes, Insect; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D014921:Wings, Animal / Q000254:growth & development; D051155:Wnt1 Protein
D029721:Drosophila Proteins; D011518:Proto-Oncogene Proteins; D051155:Wnt1 Protein; C064196:dpp protein, Drosophila; C074622:wg protein, Drosophila; D066246:ErbB Receptors