Liu Y W, Sanders M A, Basson M D
Departments of Surgery, Yale University and Connecticut VA Health Care System, New Haven, Connecticut 06520-8062, USA.
J Gastrointest Surg. 1999 Jan-Feb;3(1):82-94. doi: 10.1016/s1091-255x(99)80013-4.
Intestinal epithelial restitution and the migratory phenotype appear regulated by the extracellular matrix. Since integrin-associated adhesion to matrix triggers tyrosine kinase activity, we hypothesized that matrix-specific tyrosine kinase signals might modulate the intestinal epithelial migratory phenotype, particularly via focal adhesion kinase. Caco-2 cells were seeded at two densities on collagen I, laminin, fibronectin, and tissue culture plastic. Four days later the first cells were confluent, whereas the second cells were not contact inhibited and expressed migratory lamellipodia. Cells were fractionated into membrane/cytoskeletal and cytosolic fractions. Cytoskeletal tyrosine kinase activity in static cells was matrix dependent and, unlike cytoscolic tyrosine kinase, correlated with adhesion, highest on collagen and lowest on plastic. Migrating cells exhibited matrix-dependent increases in cystosolic tyrosine kinase activity. Cytosolic changes in tyrosine kinase activity in motile cells exceeded membrane/cytoskeletal changes. However, matrix-dependent variations in increase in cytosolic tyrosine kinase activity correlated inversely with changes in cytoskeletal tyrosine kinase activity, suggesting cytoskeletal tyrosine kinase translocation to the cytosol during motility. Indeed cytoskeletal focal adhesion kinase activity decreased during migration on collagen. Tyrosine kinase inhibition by genistein both inhibited migration and stimulated expression of brush-border enzymes downregulated during motility. Although enterocyte-matrix interactions alter both cytosolic and cytoskeletal tyrosine kinase activity, matrix-dependent cytoskeletal events are likely to regulate adhesion and differentiation in static cells. Loss of matrix-dependent cytoskeletal tyrosine kinase signals such as focal adhesion kinase during restitution may trigger a phenotypic switch to the "dedifferentiated" migrating intestinal epithelial phenotype.
肠上皮修复和迁移表型似乎受细胞外基质调控。由于整合素相关的与基质的黏附会触发酪氨酸激酶活性，我们推测基质特异性酪氨酸激酶信号可能调节肠上皮迁移表型，尤其是通过粘着斑激酶。将Caco-2细胞以两种密度接种在I型胶原、层粘连蛋白、纤连蛋白和组织培养塑料上。四天后，第一批细胞汇合，而第二批细胞未受接触抑制并表达迁移性板状伪足。细胞被分离成膜/细胞骨架和胞质部分。静态细胞中的细胞骨架酪氨酸激酶活性依赖于基质，与胞质酪氨酸激酶不同，它与黏附相关，在胶原上最高，在塑料上最低。迁移细胞的胞质酪氨酸激酶活性呈现出基质依赖性增加。运动细胞中酪氨酸激酶活性的胞质变化超过了膜/细胞骨架的变化。然而，胞质酪氨酸激酶活性增加的基质依赖性变化与细胞骨架酪氨酸激酶活性的变化呈负相关，这表明在运动过程中细胞骨架酪氨酸激酶向胞质转移。事实上，在胶原上迁移时，细胞骨架粘着斑激酶活性降低。染料木黄酮对酪氨酸激酶的抑制既抑制了迁移，又刺激了运动过程中下调的刷状缘酶的表达。尽管肠上皮细胞与基质的相互作用改变了胞质和细胞骨架酪氨酸激酶活性，但基质依赖性的细胞骨架事件可能在静态细胞中调节黏附和分化。在修复过程中，如粘着斑激酶等基质依赖性细胞骨架酪氨酸激酶信号的丧失可能触发向“去分化”的迁移性肠上皮表型的转变。
