VENTRAL VEINLESS, THE GENE ENCODING THE CF1A TRANSCRIPTION FACTOR, LINKS POSITIONAL INFORMATION AND CELL-DIFFERENTIATION DURING EMBRYONIC AND IMAGINAL DEVELOPMENT IN DROSOPHILA-MELANOGASTER

The ventral veinless gene (vvl) encodes the previously identified Cf1a protein, a transcription factor containing a POU-domain, During embry onic development vvl function is required for the formation of the tra cheal tree and in the patterning of the ventral ectoderm. During imagi nal development vvl is required for cell proliferation and the differe ntiation of the wing veins, vvl expression is restricted to the region s where its function is required, and is dependent on the coordinate a ctivities of signalling molecules such as decapentaplegic, wingless an d hedgehog, vvl interacts with other genes involved in vein differenti ation, including veinlet, thick veins, torpedo, decapentaplegic and No tch suggesting that vvl function may affect several cell-to-cell commu nication pathways, We propose that the gene vvl integrates information from different signalling molecules and regulates the expression of s pecific cell differentiation genes during tracheal development and vei n differentiation.