Involvement of actin filaments and integrins in the binding step in collagen phagocytosis by human fibroblasts.

摘要: In physiological conditions, collagen degradation by fibroblasts occurs primarily via phagocytosis, an intracellular pathway that is thought to require receptors and actin assembly for fibril internalization degradation. Currently it unclear which specific steps of phagocytosis in involve filament assembly. As studies are complicated the relatively slow rate particle compared professional phagocytes, we have examined role only initial binding step. Prior collagen-coated fluorescent beads human gingival fibroblasts, a cell type avidly phagocytic vitro, cells were treated with cytochalasin D (actin barbed-end capping) or swinholide A dimer sequestering severing) latrunculin B monomer sequestering). Bead immunostaining (alpha)(2)(beta)(1) (alpha)(3)(beta)(1) integrin measured flow cytometry. After 1–3 hours coincubation beads, eliminated filaments stained rhodamine-phalloidin inhibited bead (reductions 25% 50%, respectively), possibly because rounding restricted interactions beads. contrast, enhanced dose-dependently over controls (twofold at 1 microM) induced formation brightly staining aggregates retention long cytoplasmic extensions. Latrunculin also reduced surface (beta)(1), (alpha)(2) (alpha)(3) up 40% bead-free bead-loaded cells, indicating receptor internalization. determined fluorescence recovery after photobleaching, increased mobility surface-bound (beta)(1) integrin. The stimulatory effect on was control levels treatment inactivating antibody while blocking abrogated both latrunculin-induced stimulation. Immunoblotting bead-associated proteins showed completely (beta)-actin but did not affect binding. These data indicate sequestration monomers facilitates disengagement from receptors, increases enhances mobility. We suggest these alterations increase probability adhesive bead-to-cell interactions.