Slit2N and Robo4 influence gp120-induced hyperpermeability in L-LECs by modulating c-Src kinase activation and signaling.

<p>(<b>A</b>) Representative Western blot analysis of phosphorylated c-Src in L-LECs after preincubation with either Slit2N (500 ng/ml) or a control for 2 hours before treatment with HIV-1 gp120 (500 ng/ml) for times indicated. GAPDH used as loading control. (<b>B</b>) Robo4 immunoprecipitation of Myc-tagged Slit2 by Western blot analysis in 293 cells. 293 s were co-transfected with a Robo4 expression plasmid and either a Myc-tagged Slit2 expression plasmid or a vector control. Cells were incubated for 48 hours before the protein from total cell lysates was collected for Robo4 immunoprecipitation. (<b>C</b>) Representative Western blot analysis of phosphorylated c-Src in L-LECs after transfection with either Robo4-specific siRNAs or a control siRNA for 48 hours before treatment with HIV-1 gp120 (500 ng/ml) for times indicated. GAPDH used as loading control. (<b>D</b>) Permeability through an L-LEC monolayer as previously described. An L-LEC monolayer was pretreated with a Src kinase inhibitor (2 µM) or DMSO for 2 hours before incubating with HIV-1 gp120 (500 ng/ml) or a control for 18 hours. Data indicate the mean ± SD of 3 independent experiments. (**p<0.01 for treatment with the Src kinase inhibitor versus DMSO control).