Regulation and function of decapentaplegic during the differentiation of the wing veins. J.F. de Celis , S. Sotillos. Centro de Biologia Molecular, CSIC, Madrid, Spain.

   The decapentaplegic/TGFb-signalling pathway directs the differentiation of veins in the Drosophila wing. Soon after puparium formation decapentaplegic (dpp) is expressed in the developing veins, in a process that depends on the activity of the dpp regulatory region short vein. We have determined the extent of the short vein DNA, identifying the minimal fragments that direct the expression of a reporter gene in the pupal veins. From this analysis, it appears that the organisation of short vein is complex and contains enhancers promoting the expression of the reporter gene in individual veins. This organisation suggests that short vein is in part regulated by vein-specific transcrition factors, such as Knirps, Iroquois and Abrupt. We also identified enhancers that drive reporter gene expression in all longitudinal veins. These enhancers respond to general regulators of vein differentiation such as the Ras/MAP kinase signalling cascade and the Notch signalling pathway. The identification of the enhancers that drive the expression of dpp in pupal wings opens the posibility to connect molecularly the activity of several transcription factors and signalling pathways with the regulation of the gene that triggers vein differentiation.