Fig. 7.

Effect of chimeric α5 integrins on PC12 neurite outgrowth. A, PC12 cell lines expressing α5α5, α5α0, and α5α4 chains were surface-labeled with biotin and extracted with 1% Triton X-100. Immunoprecipitations were performed on equal amounts of protein with anti-human α5 antibody and analyzed as by SDS-PAGE on 7% gels followed by detection with streptavidin peroxidase and ECL. Note the similar levels of expression of all chimeras. B, Phase micrographs of individual PC12 cells expressing different chimeras and grown on 8V0 substrates. Note the enhanced outgrowth of the α5α4 cell line. C,Quantification of the enhanced outgrowth of the α5α4 cells. Cell lines expressing α5α5, α5α0, α5α4, and untransfected PC12 were plated on 8V0, and their neurites were measured after 24 and 48 hr. In each experiment the neurites of at least 50 cells were measured, the median was determined, and the values normalized to PC12 control after 24 hr. Data represent the mean outgrowth at 48 hr of seven separate experiments conducted with three independently generated clonal lines ± SEM. Note the enhanced outgrowth of the α5α4 cell line (*p < 0.05). D, Adhesion of α5α5, α5α0, α5α6, α5α4, and mock-transfected cell lines on FN. Adhesion assays were performed as described in Material and Methods. Plates were coated with 50 nm FN fragments. Results are reported as the mean ± SD of three experiments, each performed in quadruplicate. Note that there is no difference between the different α5 cell lines (*p < 0.05).