Requirement for integrins during Drosophila wing development

Abstract

THE position-specific (PS) integrins of Drosophila^1,2 are highly homologous to vertebrate integrins^3–5, most of which are cell-surface receptors for extracellular matrix components^6,7. Integrins are heterodimers, each consisting of noncovalently associated α- and β-subunits. As for the subfamilies of vertebrate integrins, the same β-subunit is found in both Drosophila PS integrins, combined with a specific α-subunit to generate either a complete functional PS1 or PS2 integrin^1,5,8. Both α- and β-subunits are large trans-membrane proteins (relative molecular masses > 100,000). Either one or both of these two PS integrins are expressed in most fly tissues during development. A particularly intriguing pattern of expression is found in the mature wing imaginal disc, where the PS1 integrin is expressed primarily on the presumptive dorsal wing epithelium, and the PS2 integrin is found almost exclusively on the ventral epithelium¹. Immediately after pupariation, the central wing pouch evaginates, folding along its centre to appose the epithelia that will secrete the dorsal and ventral surfaces of the adult wing blade⁹. Here we report the results of a genetic analysis indicating that both of the PS integrins are required to maintain the close apposition of the dorsal and ventral wing epithelia during morphogenesis. Also, we conclude that the integrins are not necessary for the maintenance of the cell lineage restriction between the two presumptive wing surfaces in the developing imaginal disc^10–12.