Erk and PI-3 kinase are necessary for collagen binding and actin reorganization in corneal epithelia.
Erk and PI-3 kinase are necessary for collagen binding and actin reorganization in corneal epithelia.
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发表时间：
2000-10
影响因子：
4.4
通讯作者：
C. L. Chu;W. Reenstra;D. Orlow;K. Svoboda
中科院分区：
文献类型：
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作者：
C. L. Chu;W. Reenstra;D. Orlow;K. Svoboda
目的研究兔角膜上皮损伤后磷脂酰肌醇-（PI）3激酶的表达。胚胎角膜上皮细胞经I型胶原刺激1小时后，细胞外信号调节激酶（erk）-1和-2蛋白以及PI-3激酶被激活。在目前的研究中，PI-3激酶和促分裂原激活的激酶-激酶（MEK-1激酶）的特异性抑制剂被用来确定这些信号分子在肌动蛋白重组和胶原蛋白结合到角膜上皮组织的分离片中的作用。方法应用特异性PI-3激酶和MEK-1抑制剂LY 294002、PD 98059对人胚胎角膜上皮细胞进行体外培养，观察其对角膜上皮细胞增殖的影响。将禽胚胎角膜上皮分离为组织片，在这些特异性抑制剂的存在下培养器官，并用I型胶原刺激。评价组织的胶原刺激的肌动蛋白重组、erk-1和erk-2以及PI-3激酶活性、总丝状肌动蛋白积累和胶原结合。结果MEK-1抑制剂PD 98059以剂量依赖性方式降低erk-1和erk-2的磷酸化水平，阻断肌动蛋白重组。PI-3激酶85-kDa亚基在LY 294002处理的组织中降低了25%，并且与对照组织相比，在用MEK-1和PI-3激酶抑制剂处理的组织中胶原结合也显著降低。此外，这两种抑制剂阻止肌动蛋白皮质垫重组。结论; PI-3激酶和erk-1和erk-2信号通路被激活，是胚胎禽角膜上皮胶原结合和整合素介导的肌动蛋白重组所必需的。
PURPOSE It was recently shown that phosphatidylinositol-(PI)3 kinase is upregulated in wounded rabbit corneal epithelia. Extracellular signal-regulated kinase (erk)-1 and -2 proteins and PI-3 kinase were activated in embryonic corneal epithelia after 1-hour stimulation by type I collagen. In the current investigation specific inhibitors of PI-3 kinase and mitogen-activated kinase-kinase (MEK-1 kinase) were used to determine the role of these signaling molecules in actin reorganization and collagen binding to isolated sheets of corneal epithelial tissue. METHODS Effects of specific PI-3 kinase and MEK-1 inhibitors (LY294002, PD98059, respectively) were investigated in embryonic corneal epithelial tissues. Avian embryonic corneal epithelia were isolated as tissue sheets, organ cultured in the presence of these specific inhibitors, and stimulated with type I collagen. The tissues were evaluated for collagen-stimulated actin reorganization, erk-1 and -2 and PI-3 kinase activity, total filamentous actin accumulation, and collagen binding. RESULTS The MEK-1 inhibitor PD98059 decreased erk-1 and -2 phosphorylation and blocked actin reorganization in a dose-dependent manner. The PI-3 kinase 85-kDa subunit was decreased 25% in LY294002-treated tissue, and collagen binding also decreased significantly in tissues treated with MEK-1 and PI-3 kinase inhibitors compared with control tissues. In addition, both inhibitors blocked actin cortical mat reorganization. CONCLUSIONS; PI-3 kinase and erk-1 and -2 signaling pathways are activated and necessary for collagen binding and integrin-mediated actin reorganization in embryonic avian corneal epithelium.