Deficiency screen identifies a novel role for beta 2 tubulin in salivary gland and myoblast migration in the Drosophila embryo.

The Drosophila embryonic salivary gland is an epithelial organ formed by the coordinated invagination and migration of primordial cells. To identify genes that regulate gland migration we performed a deficiency screen of the third chromosome. Here, we report on the analysis of the beta 2 tubulin isoform (beta2t) that maps at 85D15. We show that, in beta2t mutant embryos, salivary glands did not complete their posterior migration and that migration of fusion competent myoblasts and longitudinal visceral muscle founder cells between the gland and circular visceral mesoderm was delayed. We also demonstrate that gland migration defects correlate with reduced betaPS and alphaPS2 integrin expression in the surrounding mesoderm and that beta2t genetically interacts with genes encoding integrin alphaPS1 and alphaPS2 subunits. Our studies reveal for the first time that beta2t is expressed in embryogenesis and that beta2t plays an important role in salivary gland and myoblast migration, possibly through proper regulation of integrin adhesion proteins.