Signaling by the TGF-beta homolog decapentaplegic functions reiteratively within the network of genes controlling retinal cell fate determination in Drosophila

Retinal cell fate determination in Drosophila is controlled by an interacti ve network of genes, including eyeless, eyes absent, sine oculis and dachsh und. We have investigated the role of the TGF-beta homolog decapentaplegic in this pathway, We demonstrate that, during eye development, while eyeless transcription does not depend on decapentaplegic activity, the expression of eyes absent, sine oculis and dachshund are greatly reduced in a decapent aplegic mutant background. We also show that decapentaplegic signaling acts synergistically with and at multiple levels of the retinal determination n etwork to induce eyes absent, sine oculis and dachshund expression and ecto pic eye formation. These results suggest a mechanism by which a general pat terning signal such as Decapentaplegic cooperates reiteratively with tissue -specific factors to determine distinct cell fates during development.