DFak56 is a novel Drosophila melanogaster focal adhesion kinase

The mammalian focal adhesion kinase (FAK) family of nonreceptor protein-tyr osine kinases have been implicated in controlling a multitude of cellular r esponses to the engagement of cell surface integrins and G protein-coupled receptors. We describe here a Drosophila melanogaster FAK homologue, DFak56 , which maps to band 56D on the right arm of the second chromosome. Full-le ngth DFak56 cDNA encodes a phosphoprotein of 140 kDa, which shares strong s equence similarity not only with mammalian p125(FAK) but also with the more recently described mammalian Pyk2 (also known as CAR beta, RAFTK, FAK2, an d CADTK) FAK family member. DFak56 has intrinsic tyrosine kinase activity a nd is phosphorylated on tyrosine in vivo. As is the case for FAK, tyrosine phosphorylation of DFak56 is increased upon plating Drosophila embryo cells on extracellular matrix proteins. In situ hybridization and immunofluoresc ence staining analysis showed that DFak56 is ubiquitously expressed with pa rticularly high levels within the developing central nervous system, We uti lized the UAS-GAIA expression system to express DFak56 and analyze its func tion in vivo. Overexpression of DFak56 in the wing imaginal disc results in wing blistering in adults, a phenotype also observed with both position-sp ecific integrin loss of function and position-specific integrin overexpress ion. Our results imply a role for DFak56 in adhesion-dependent signaling pa thways in viva during D. melanogaster development.