Gayer Christopher P, Chaturvedi Lakshmi S, Wang Shouye, Alston Brittany, Flanigan Thomas L, Basson Marc D
Department of Surgery, John D. Dingell VA Medical Center, Wayne State University, Detroit, MI, USA.
Am J Physiol Gastrointest Liver Physiol. 2009 Apr;296(4):G876-85. doi: 10.1152/ajpgi.90648.2008. Epub 2009 Jan 29.
Repetitive strain stimulates intestinal epithelial migration across fibronectin via focal adhesion kinase (FAK), Src, and extracellular signal-related kinase (ERK) although how these signals act and interact remains unclear. We hypothesized that PI3K is central to this pathway. We subjected Caco-2 and intestinal epithelial cell-6 cells to 10 cycles/min deformation on flexible fibronectin-coated membranes, assayed migration by wound closure, and signaling by immunoblots. Strain stimulated PI3K, AKT, glycogen synthase kinase (GSK), and p38 phosphorylation. Blocking each kinase prevented strain stimulation of migration. Blocking PI3K prevented strain-stimulated ERK and p38 phosphorylation. Blocking AKT did not. Downstream, blocking PI3K, AKT, or ERK inhibited strain-induced GSK-Ser9 phosphorylation. Upstream of AKT, reducing FAK or Rac1 by siRNA blocked strain-stimulated AKT phosphorylation, but inhibiting Src by PP2 or siRNA did not. Transfection with FAK point mutants at Tyr397, Tyr576/577, or Tyr925 demonstrated that only FAK925 phosphorylation is required for strain-stimulated AKT phosphorylation. Myosin light chain activation by strain required FAK, Rac1, PI3K, AKT, GSK, and ERK but not Src or p38. Finally, blebbistatin, a nonmuscle myosin II inhibitor, blocked the motogenic effect of strain downstream of myosin light chain. Thus strain stimulates intestinal epithelial migration across fibronectin by a complex pathway including Src, FAK, Rac1, PI3K, AKT, GSK, ERK, p38, myosin light chain, and myosin II.
重复性应变通过粘着斑激酶(FAK)、Src和细胞外信号调节激酶(ERK)刺激肠上皮细胞跨纤连蛋白迁移,尽管这些信号如何发挥作用以及相互作用尚不清楚。我们假设PI3K是该信号通路的核心。我们将Caco-2细胞和肠上皮细胞-6置于涂有纤连蛋白的柔性膜上,以每分钟10次循环的频率进行变形处理,通过伤口闭合实验检测细胞迁移情况,并通过免疫印迹法检测信号传导。应变刺激了PI3K、AKT、糖原合酶激酶(GSK)和p38的磷酸化。阻断每种激酶均可阻止应变对迁移的刺激作用。阻断PI3K可阻止应变刺激的ERK和p38磷酸化。阻断AKT则不能。在下游,阻断PI3K、AKT或ERK可抑制应变诱导的GSK-Ser9磷酸化。在AKT上游,通过小干扰RNA(siRNA)降低FAK或Rac1可阻断应变刺激的AKT磷酸化,但用PP2或siRNA抑制Src则不能。用FAK Tyr397、Tyr576/577或Tyr925位点的点突变体进行转染实验表明,只有FAK925位点的磷酸化是应变刺激AKT磷酸化所必需的。应变诱导的肌球蛋白轻链激活需要FAK、Rac1、PI3K、AKT、GSK和ERK,但不需要Src或p38。最后,非肌肉型肌球蛋白II抑制剂blebbistatin可阻断肌球蛋白轻链下游应变的促迁移作用。因此,应变通过包括Src、FAK、Rac1、PI3K、AKT、GSK、ERK、p38、肌球蛋白轻链和肌球蛋白II的复杂信号通路刺激肠上皮细胞跨纤连蛋白迁移。