Figure 2

Incubation with apical or basolateral LPA stimulated apical secretion of CTGF. A: Polarized hPTEC were stimulated with LPA (10 μM) from the basolateral side (L-b) or from the apical side (L-a) for 2 and 4 h. CTGF was detected in the apical compartment. The graph summarizes data (means +/− SD) of 5 (2 h) and 3 (4 h) independent experiments. Values of secretion of control cells were set to 1 at each time point. * p < 0.05; ** p < 0.01, Dunnet’s multiple comparison test. B/C: Polarized hPTEC were stimulated with LPA (10 μM) from the apical or basolateral side for 1 h. CTGF and E-cadherin were visualized by immunocytochemistry. Nuclei were stained with Hoechst. Cells negative for E-cadherin represent proximal tubular cells. Newly synthesized CTGF was detectable in a perinuclear localization (C; nuclei colored in red; CTGF in green, scale bar: 10 μm). Arrows indicate examples of CTGF positive proximal cells. Scale bar: 50 μm. D: Polarized hPTEC were pre-incubated with the inhibitors (U0: U0106, 1 μM; SB203: SB203580 1 μM; Y27: Y27632, 10 μM) for 30 min and then stimulated with LPA (10 μM) from the apical and basolateral side for 4 h. Secreted CTGF was detected in the apical (a) and basolateral (b) compartment. The graph summarizes data obtained with two isolations. Apical secretion of LPA-stimulated cells was set to 1 in each experiment.