43rd ANNUAL DROSOPHILA RESEARCH CONFERENCE
April 10-14, 2002

PROGRAM AND ABSTRACT VOLUME
Workshop Abstract

4W
Epithelial morphogenesis and repair in the fly embryo. P. Martin. Dept. of Anatomy and Developmental Biology, University College London, London, N1 OHW, UK. +020 7679 3362

Using live confocal imaging of transgenic Drosophila embryos expressing gfp-actin in epithelial tissues we have revealed the key actin machineries that drive the paradigm morphogenetic process of dorsal closure which appears to bear striking analogy with re-epithelialisation of a vertebrate skin wound. Using mutant embryos we have tested the function of each of these actin-based elements, the actin cable and dynamic filopodia and lamellipodia. We have shown that filopodia play crucial roles in both adhering the zippering epithelial faces together and in the appropriate cell:cell matching necessary for correct segment alignment along the midline seam (Jacinto et al, 2000 - Curr Biol 10, 1420-1426), whilst the actin cable appears to play a restraining role, maintaining a taut, smooth lead epithelial edge which aids in aligning the two epithelial sheets as they fuse in the midline. Parallel studies of GFP-actin expressing fly embryos after laser wounding are revealing the close molecular genetic analogies between wound closure and dorsal closure - we show that an actin cable and dynamic filopodia rapidly assemble in wound edge epithelial cells and we have tested the function of these structures by modulating the function of various of the Rho family small GTPases. These experiments suggest that flies will provide us with the best opportunity for dissecting the fundamental genetic mechanisms underlying epithelial repair.

Signaling in the Eye