The overall goal of this project is to gain a detailed understanding of the molecular function of integrins, a large family of cell surface receptors. Integrins are involved in many developmental processes and also function in numerous fully differentiated cells. With respect to known pathological conditions, most studies of integrins have focused on the circulatory system, the immune system, and the metastasis of tumors, however it is likely that integrins will prove to be important in pathologies in other tissues and diseases as well. The PS integrins of Drosophila are very similar to vertebrate integrins, and provide a unique opportunity to examine integrin function in situ in a complex developmental system. We propose to: (1) Further define the interaction of PS2 integrin with the fly matrix protein tiggrin, using our cell spreading assay and genetically engineered fragments of the tiggrin protein. Also, begin steps to generate mutations in the tiggrin gene, in order to undertake a genetic analysis of tiggrin function during development. (2) Define the requirements for PS l integrin during development, using newly generated mutations in the mew gene, which encodes the alphaPS1 integrin subunit. This study will focus on Comparisons between the myospheroid (betaPS), inflated (alphaPS2) and mew phenotypes, and include analysis of genetic mosaics. (3) Continue to generate and characterize hypomorphic mutations of myospheroid, and combine this with cell culture and phenotypic analyses to define domains of integrins required for specific integrin functions. (4) Develop methods for the regulated expression of PS integrin transgenes in the developing wing of Drosophila, with the goal of using wing as a model system for the fine dissection of integrin function during morphogenesis in situ. This phase of the project will include use of GAL4 enhancer trap technology as well as dissection of the regulatory regions of integrin genes, in order to find enhancers that can provide the required patterns of integrin transgene expression. (5) Use the transgenes in (4) in combination with the integrin mutants to dissect the detailed functions of integrins and integrin """"""""parts"""""""" during wing morphogenesis. This will involve the generation of clones of cells mutant for integrin function, and attempts to rescue the mutant phenotypes by expression of normal and genetically altered integrin transgenes.
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