title: Matrix-specific FAK and MAPK reorganization during Caco-2 cell motility.
abstract: We have previously reported that Caco-2 cell motility redistributes FAK, paxillin, and activates p38. However, the subcellular organization of these intracellular signals during cell migration is unclear. We, therefore, investigated the organization of actin, FAK, paxillin, and activated ERK and activated p38 during Caco-2 motility across collagen I, fibronectin, laminin, and tissue culture treated glass. Differential density seeding generated homogeneous static and migrating populations. Expression of actin, FAK, paxillin, phospho-ERK, and phospho-p38 were examined by immunofluorescent staining in static and motile cells. Actin was concentrated toward the peri-nuclear central area of cells migrating on matrix proteins studied. Actin immunoreactivity was decreased in the leading edge of lamellipodia. FAK immunoreactivity was weaker in migrating cells than in static cells on the same matrix. FAK was expressed along cell-cell contacts of both cell populations, but absent in migrating lamellipodia of matrix-cultured cells. Paxillin staining was diffuse in static cells but organized toward migrating lamellipodia in a radial manner. Like FAK, phosphorylated ERK was expressed in the central region of migrating cells but was dramatically decreased at areas of cell-cell contact and free lamellipodia. Fibronectin exerted the greatest effect on ERK activation in all matrix proteins studied. In contrast, phosphorylated p38 staining was stronger in migrating cells on matrix than in static cells on the same matrix. Phosphorylated p38 was expressed in the nuclear of migrating cells and disappeared in the cell-cell contact side and free lamellipodia. Interestingly, the reorganization of these proteins was distinctly different on tissue culture treated glass without a physiologic matrix substrate. For instance, FAK staining increased rather than decreased in motile cells on plastic, and lamellipodial FAK staining could be discerned. Matrix may influence Caco-2 biology during migration not only by triggering intracellular phosphorylation events but also by reorganizing the cytoskeleton and the subcellular localization of these intracellular signals.
authors.affiliation: Departments of Surgery, Yale University School of Medicine and CT VA Health Care System, New Haven, Connecticut 06511, USA.
authors.forename: C F
authors.initials: CF
authors.lastname: Yu
authors.forename: M D
authors.initials: MD
authors.lastname: Basson
mesh_terms: D000199:Actins / Q000378:metabolism; D018938:Caco-2 Cells; D002450:Cell Communication; D002465:Cell Movement; D003094:Collagen / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000032:analysis; D004789:Enzyme Activation; D005353:Fibronectins / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D007797:Laminin / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis / Q000378:metabolism*; D051419:Paxillin; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; D005353:Fibronectins; D007797:Laminin; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D003094:Collagen; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases