tailup, a LIM-HD gene, and Iro-C cooperate in Drosophila dorsal mesothorax specification.
The LIM-HD gene tailup (tup; also known as islet) has been categorised as a prepattern gene that antagonises the formation of sensory bristles on the notum of Drosophila by downregulating the expression of the proneural achaete-scute genes. Here we show that tup has an earlier function in the development of the imaginal wing disc; namely, the specification of the notum territory. Absence of tup function causes cells of this anlage to upregulate different wing-hinge genes and to lose expression of some notum genes. Consistently, these cells differentiate hinge structures or modified notum cuticle. The LIM-HD co-factors Chip and Ssdp are also necessary for notum specification. This suggests that Tup acts in this process in a complex with Chip and Ssdp. Overexpression of tup, together with araucan, a 'pronotum' gene of the iroquois complex (Iro-C), synergistically reinforces the weak capacity of either gene, when overexpressed singly, to induce ectopic notum-like development. Whereas the Iro-C genes are activated in the notum anlage by EGFR signalling, tup is positively regulated by Dpp signalling. Our data support a model in which the EGFR and Dpp signalling pathways, with their respective downstream Iro-C and tup genes, converge and cooperate to commit cells to the notum developmental fate.
de Navascués
Joaquín
J
Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Cantoblanco, Madrid, Spain.
Modolell
Juan
J
D000818:Animals; D019521:Body Patterning; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014921:Wings, Animal / Q000196:embryology
C099257:ARA protein, Drosophila; C108740:Chi protein, Drosophila; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; C520429:Ssdp protein, Drosophila; D014157:Transcription Factors; C494337:tup protein, Drosophila