Figure 5.

Myofibroblast AJs provide mechanical resistance. SCFs were grown for 5 d with TGFβ (M) and without (F) on the bottom of a parallel-plate flow chamber; similarly treated SCFs were seeded onto this cell monolayer and adhered for 30 min. (A) Cells were stained for α-SMA (red) and β-catenin (green), and series of optical sections of 0.2 μm were produced using laser scanning confocal microscopy. Formation of AJs is demonstrated between a suspended myofibroblast (encircled area) and at the dorsal membrane of a plated myofibroblast, reconstructed from three optical sections at the cell-cell interface and in z-scans performed along the indicated lines. Bar, 10 μm. (B) Reinforcement of the cortical actin of a suspended cell and insertion of stress fibers of a plated cell at contact sites is schematized. (C and D) Cell pairs were subjected to hydrodynamic shear forces, ranging from 1 to 4 Nm^–2 and the percentage of remaining suspended cells compared with the initially seeded cell number was determined before and after steps of 1 Nm^–2 min^–1 in control conditions (C and D, dotted lines) and in the presence of SMA-FP (5 μg/ml) (D). Note that homotypic myofibroblast pairs (M on M) exhibit higher intercellular adhesion compared with homotypic pairs of fibroblasts (F on F). SMA-FP reduces cell-cell attachment when fibroblasts were seeded onto myofibroblasts (F on M) but not in the reverse setup (M on F).