Figure 2

Mutations in the paxillin-binding region of the α4 cytoplasmic domain inhibit α4-mediated neurite outgrowth. A) Neurite outgrowth from PC12 cells expressing the different α4 constructs after 24 hrs plated onto recombinant Fn fragments containing the V120 sequence (Fn V120, 50 nM) within which the α4-binding LDV motif is present. In each experiments the longest neurites in at least 100 cells were measured and the results normalised to the median values seen in cells expressing wild type α4. The data shown are the mean ± SEM of 6 experiments. Note the reduction in the single mutants (* = P < 0.01), and complete loss of any α4-mediated outgrowth with the double mutant and cytoplasmic domain deletion (** = P < 0.005), with levels now the same as those seen on mock-transfected PC12 cells. B) Neurite outgrowth from mock-transfected PC12 cells and those expressing wild-type α4 or the double mutant. Note that, as in A), outgrowth on Fn V120 requires a normal α4 cytoplasmic domain while outgrowth on laminin and collagen does not and is similar in all cell lines. C) Representative examples of neurite outgrowth in PC12 cells expressing the different α4 constructs.