Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
Biochem J. 2011 Oct 1;439(1):45-55. doi: 10.1042/BJ20110274.
Lung cell migration is a crucial step for re-epithelialization that in turn is essential for remodelling and repair after lung injury. In the present paper we hypothesize that secreted ATX (autotaxin), which exhibits lysoPLD (lysophospholipase D) activity, stimulates lung epithelial cell migration through LPA (lysophosphatidic acid) generation-dependent and -independent pathways. Release of endogenous ATX protein and activity was detected in lung epithelial cell culture medium. ATX with V5 tag overexpressed conditional medium had higher LPA levels compared with control medium and stimulated cell migration through G(αi)-coupled LPA receptors, cytoskeleton rearrangement, phosphorylation of PKC (protein kinase C) δ and cortactin at the leading edge of migrating cells. Inhibition of PKCδ attenuated ATX-V5 overexpressed conditional medium-mediated phosphorylation of cortactin. In addition, a recombinant ATX mutant, lacking lysoPLD activity, or heat-inactived ATX also induced lung epithelial cell migration. Extracelluar ATX bound to the LPA receptor and integrin β4 complex on A549 cell surface. Finally, intratracheal administration of LPS (lipopolysaccharide) into the mouse airway induced ATX release and LPA production in BAL (bronchoalveolar lavage) fluid. These results suggested a significant role for ATX in lung epithelial cell migration and remodelling through its ability to induce LPA production-mediated phosphorylation of PKCδ and cortactin. In addition we also demonstrated association of ATX with the epithelial cell-surface LPA receptor and integrin β4.
肺细胞迁移是上皮细胞再形成的关键步骤，而后者对于肺损伤后的重塑和修复至关重要。在本文中，我们假设分泌的 ATX（自分泌酶）具有溶脂酶 D（lysophospholipase D）活性，通过 LPA（溶血磷脂酸）生成依赖性和非依赖性途径刺激肺上皮细胞迁移。在肺上皮细胞培养基中检测到内源性 ATX 蛋白和活性的释放。与对照培养基相比，过表达 V5 标签的 ATX 条件培养基具有更高的 LPA 水平，并通过 G（αi）偶联的 LPA 受体、细胞骨架重排、PKC（蛋白激酶 C）δ 和皮质肌动蛋白在迁移细胞的前缘磷酸化来刺激细胞迁移。PKCδ 抑制减弱了 ATX-V5 过表达条件培养基介导的皮质肌动蛋白磷酸化。此外，缺乏溶脂酶 D 活性的重组 ATX 突变体或热失活的 ATX 也能诱导肺上皮细胞迁移。细胞外 ATX 与 A549 细胞表面的 LPA 受体和整合素 β4 复合物结合。最后，向小鼠气道中气管内给予 LPS（脂多糖）会诱导 BAL（支气管肺泡灌洗）液中 ATX 的释放和 LPA 的产生。这些结果表明，ATX 通过诱导 LPA 产生介导的 PKCδ 和皮质肌动蛋白磷酸化，在肺上皮细胞迁移和重塑中发挥重要作用。此外，我们还证明了 ATX 与上皮细胞表面的 LPA 受体和整合素 β4 有关。
