DISTINCT ROLES FOR THE ACTIN AND MICROTUBULE CYTOSKELETONS IN THE MORPHOGENESIS OF EPIDERMAL HAIRS DURING WING DEVELOPMENT IN DROSOPHILA

We have found that the actin and microtubule cytoskeletons have overla pping, but distinct roles in the morphogenesis of epidermal hairs duri ng Drosophila wing development. The function of both the actin and mic rotubule cytoskeletons appears to be required for the growth of wing h airs, as treatment of cultured pupal wings with either cytochalasin D or vinblastine was able to slow prehair extension. At higher doses a c omplete blockage of hair development was seen. The microtubule cytoske leton is also required for localizing prehair initiation to the distal most part of the cell. Disruption of the microtubule cytoskeleton resu lted in the development of multiple prehairs along the apical cell per iphery. The multiple hair cells were a phenocopy of mutations in the i nturned group of tissue polarity genes, which are downstream targets o f the frizzled signaling/signal transduction pathway. The actin cytosk eleton also plays a role in maintaining prehair integrity during preha ir development as treatment of pupal wings with cytochalasin D, which inhibits actin polymerization, led to branched prehairs. This is a phe nocopy of mutations in crinkled, and suggests mutations that cause bra nched hairs will be in genes that encode products that interact with t he actin cytoskeleton. (C) 1998 Elsevier Science Ireland Ltd.