Zhang Jianhu, Owen Cheri R, Sanders Matthew A, Turner Jerrold R, Basson Marc D
Department of Surgery, John D. Dingell VA Medical Center, 4646 John R. Street, Detroit, MI 48301, USA.
Gastroenterology. 2006 Oct;131(4):1179-89. doi: 10.1053/j.gastro.2006.08.007. Epub 2006 Aug 16.
BACKGROUND & AIMS: Complex deformation during normal digestion due to peristalsis or villous motility may be trophic for the intestinal mucosa. Because tissue fibronectin is increased in inflammatory states that may accompany mucosal injury, we evaluated the effects of cyclic mechanical strain and fibronectin on intestinal epithelial monolayer wound closure in Caco-2 and IEC-6 intestinal epithelial cells.
Wounds created in intestinal epithelial monolayers were subjected to cyclic deformation. Wound closure was assessed by morphometry using microscopic imaging. Cell signals were assessed by Western blot and confocal microscopy.
Mechanical strain stimulated wound closure on fibronectin but inhibited closure on collagen in Caco-2 and IEC-6 cells. The effect was independent of proliferation or cell spreading. Myosin light chain (MLC) and extracellular signal-regulated kinase (ERK) were phosphorylated in response to strain in confluent monolayers on both collagen and fibronectin. Blocking MLC or ERK phosphorylation inhibited the motogenic effect of strain on fibronectin. Although phosphorylated MLC was redistributed to the leading edge of migrating cells following 6 hours of strain on collagen and fibronectin, phosphorylated ERK was redistributed to the lamellipodial edge only on fibronectin.
Strain promotes intestinal epithelial wound closure by a pathway requiring ERK and MLC kinase. Fibronectin-dependent ERK redistribution in response to strain in confluent migrating cells may explain the matrix dependence of the motogenic effect. Repetitive deformation stimulates intestinal epithelial proliferation on a collagen substrate, but not fibronectin. Deformation may exert matrix-dependent effects on intestinal epithelial cells, promoting epithelial restitution in fibronectin-rich tissue and proliferation in fibronectin-poor mucosa.
正常消化过程中因蠕动或绒毛运动产生的复杂形变可能对肠黏膜具有营养作用。由于在可能伴随黏膜损伤的炎症状态下组织纤连蛋白会增加，我们评估了周期性机械应变和纤连蛋白对Caco - 2和IEC - 6肠上皮细胞单层肠上皮伤口愈合的影响。
对肠上皮细胞单层造成的伤口施加周期性形变。使用显微镜成像通过形态测量法评估伤口愈合情况。通过蛋白质免疫印迹法和共聚焦显微镜评估细胞信号。
在Caco - 2和IEC - 6细胞中，机械应变促进纤连蛋白上的伤口愈合，但抑制胶原蛋白上的伤口愈合。该效应与增殖或细胞铺展无关。在胶原蛋白和纤连蛋白上的汇合单层细胞中，肌球蛋白轻链（MLC）和细胞外信号调节激酶（ERK）因应变而磷酸化。阻断MLC或ERK磷酸化可抑制应变对纤连蛋白的促运动效应。尽管在胶原蛋白和纤连蛋白上施加6小时应变后，磷酸化的MLC重新分布到迁移细胞的前沿，但磷酸化的ERK仅在纤连蛋白上重新分布到片状伪足边缘。
应变通过需要ERK和MLC激酶的途径促进肠上皮伤口愈合。汇合迁移细胞中纤连蛋白依赖性ERK因应变而重新分布，这可能解释了促运动效应的基质依赖性。重复形变刺激胶原蛋白底物上的肠上皮增殖，但不刺激纤连蛋白上的增殖。形变可能对肠上皮细胞产生基质依赖性影响，促进富含纤连蛋白组织中的上皮修复以及纤连蛋白含量低的黏膜中的增殖。
