Figure 4.

VZG-1 is required for LPA-dependent neurite retraction/cell rounding through Rho activation. Phase contrast microscopy of parental B103 cells (A and B), stable clone for antisense vzg-1 (clone A-5; C and D) or a stable clone for sense vzg-1 (clone S-3; E and F). Cells were treated with control vehicle buffer (A, C, and E) or with 1 μM LPA (B, D, and F) for 30 min. Only the sense-transfected cells exposed to LPA retracted neurites (F). (G) Dose–response relationship of LPA to neurite retraction in control and experimental B103 stable cell lines. Three independently derived, sense-expressing cell lines (S-3, S-4, and S-7) were compared with control cell lines (B103, parental line; E-7, empty vector-transfected line; and A-5, antisense-transfected line). Cells were treated with varying concentrations of LPA and fixed, and the percentages of neurite-retracted cells were determined. Data are the mean ± SEM (n ≥ 3). Only vzg-1 sense-transfected lines respond to LPA exposure. (H) Effect of functional PTX or his-C3 exoenzyme on LPA-induced neurite retraction. Sense-expressing clone S-3 was incubated with or without PTX or his-C3 exoenzyme and then analyzed for neurite retraction/cell rounding. Data are the mean ± SEM (n = 4). ∗, P < 0.05 (using Student’s t test) vs. no LPA. #, P < 0.05 vs. 1 μM LPA in nontreated cultures (None). See Experimental Procedures for abbreviations.