FIGURE 6.

Matriptase is the crucial activator of Caco-2 barrier closure. A, stimulation of TEER development by recombinant matriptase. Four day Caco-2 monolayers on Transwell filters (TEER ∼ 250 ohms·cm²) were treated on the basolateral side with the indicated concentrations of recombinant matriptase, and TEER was monitored over the course of 5 h. The graph shows the change in TEER relative to the TEER measured at time 0. B, basolateral matriptase is required for TEER development. Four day Caco-2 monolayers on (TEER ∼ 650 ohms·cm²) were treated on the apical or basal sides with 5 nm recombinant matriptase or inactive G827R-matriptase. The graph shows the change in TEER relative to the TEER measured at time 0. C, endogenous prostasin is not required for the induction of TEER development by recombinant matriptase. Prostasin (siP1)-depleted Caco-2 monolayers were treated on the basal side on day 4 with 5 nm recombinant matriptase (siP1 + rMatriptase) or left untreated, and TEER was measured relative to control cultures (control siRNA (siCtl)) over the course of 5 h. Graphs show mean ± S.E. from triplicate wells.