FIGURE 9:

TNF-α enhances epithelial migration through GEF-H1, TACE, and ERK. (A, B) GEF-H1 mediates TNF-α–induced enhanced migration. LLC-PK₁ cells were transfected with NR or GEF-H1-specific siRNA and 24 h later plated into wells of an ECIS 8W1E array and grown with continuous measurement of C at 32 kHz until confluence was reached (indicated by C reaching its minimum value). Next a wound was generated by applying an elevated voltage pulse. Where indicated, before wounding the cells were treated with 20 ng/ml TNF-α. Recovery of the layer was monitored by measuring C at 32 kHz. Typical recovery curves are shown. The graph in B shows the half–recovery times for each condition, calculated as described in Materials and Methods. Values for the controls were taken as unity, and the other conditions were expressed as fold changes. Mean ± SEM of n = 4 independent experiments performed in duplicate. Note that although the trend was detectable in all experiments, the combined data do not reach statistical significance. (C–E) TACE and ERK are required for TNF-α–induced enhanced migration. Wound-healing assays using LLC-PK₁ cells were performed as described. Where indicated, before wounding the cells were treated with 20 ng/ml TNF-α with or without 10 μM TAPI-1 or PD98059. In E, half–recovery times are shown (mean ± SEM of n = 4 independent experiments, performed in duplicate).