Fig. 5.

Integrin function and expression in DRG neurons and PC12 cells. A, Direct comparison of neurite outgrowth of DRG neurons and PC12 cells on FN after 24 hr.B, Effect of the V region on neurite outgrowth of PC12 cells. PC12 were plated on 8V120, 8V95, and 8V0, ± RGD peptides, and 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 were normalized relative to the neurite outgrowth on 8V120 after 24 hr. Data represent the mean outgrowth at 48 hr from five separate experiments ± SEM. Note that PC12 cells do not show increased neurite outgrowth on V120-containing fragments and that outgrowth on all fragments is essentially completely blocked with RGD peptides (*p < 0.01). C, Cell lysates from DRG neurons (surface-labeled with biotin) were precipitated with anti-α4 Ab, anti-α5 Ab, and anti-β1 Ab. Immunoprecipitated proteins (equal amounts of protein were loaded) were separated by SDS-PAGE on 7% gels under nonreducing conditions, transferred to a nitrocellulose membrane, and detected with streptavidin peroxidase and ECL. Note that the neurons express both α4β1 and α5β1. D, Cell lysates from PC12 cell (surface-labeled with biotin) were immunoprecipitated with anti-α1, anti-α2, anti-α3, anti-α4, anti-α5, anti-α6, anti-αv, and anti-β1 antibodies and visualized as with the DRG neurons. Note that PC12 cells express low levels of α5 but no α4.