PS2 Integrin Requirements in Drosophila Embryo and Wing Morphogenesis

Abstract

The Drosophila inflated ( if) gene encodes the α PS2 sub-unit of the PS integrins. We describe the generation of new if mutations, their lethal embryonic phenotype, and experiments that examine the spatial and temporal requirements for integrins in adult wing morphogenesis. Embryos hemizygous for either new allele, if A7 or if B2, make reduced amounts of α PS2. In a variety of genetic tests, these alleles behave similarly to if h27e , which makes no detectable α PS2, and all three alleles display the same embryonic phenotype. We therefore conclude that all of the lethal alleles retain little or no wild-type α PS2 function. As seen for strong mutations at the myospheroid ( mys) locus, which encodes the β PS integrin subunit, if mutants show extreme defects in somatic muscle attachments and in midgut morphogenesis. Unlike mys, however, there is no dorsal herniation of the if mutant embryos. With respect to wing morphogenesis, clonal analysis experiments demonstrate that if + function is required only in cells of the ventral wing surface. We have rescued the wing blister phenotype of double mutants for the hypomorphic mys nj42 and if 3 alleles using a heat shock-inducible mys + transgene. By varying times of transgene induction, we find that integrin function is required from very early in metamorphosis until at least the last 24-48 hr of wing development.