Cuvelier Susan L, Paul Smitha, Shariat Neda, Colarusso Pina, Patel Kamala D
Department of Physiology and Biophysics, Immunology Research Group, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
J Exp Med. 2005 Sep 19;202(6):865-76. doi: 10.1084/jem.20041315.
Leukocyte transmigration can be affected by shear stress; however, the mechanisms by which shear stress modulates transmigration are unknown. We found that adhesion of eosinophils or an eosinophilic cell line to intereukin 4-stimulated endothelial cells led to a shear-dependent increase in endothelial cell intracellular calcium and increased phosphorylation of extracellular signal-regulated kinase (ERK) 2, but not c-Jun NH2-terminal kinase or p38 mitogen-activated protein kinase. Latex beads coated with antibodies were used to characterize the role of specific endothelial cell surface molecules in initiating signaling under shear conditions. We found that ligation of either vascular cell adhesion molecule-1 or E-selectin, but not major histocompatibility complex class I, induced a shear-dependent increase in ERK2 phosphorylation in cytokine-stimulated endothelial cells. Disassembly of the actin cytoskeleton with latrunculin A prevented ERK2 phosphorylation after adhesion under flow conditions, supporting a role for the cytoskeleton in mechano-sensing. Rapid phosphorylation of focal adhesion kinase and paxillin occurred under identical conditions, suggesting that focal adhesions were also involved in mechanotransduction. Finally, we found that Rho-associated protein kinase and calpain were both critical in the subsequent transendothelial migration of eosinophils under flow conditions. These data suggest that ligation of leukocyte adhesion molecules under flow conditions leads to mechanotransduction in endothelial cells, which can regulate subsequent leukocyte trafficking.
白细胞迁移会受到剪切应力的影响;然而,剪切应力调节迁移的机制尚不清楚。我们发现,嗜酸性粒细胞或嗜酸性细胞系与白细胞介素4刺激的内皮细胞的黏附会导致内皮细胞内钙的剪切依赖性增加以及细胞外信号调节激酶(ERK)2的磷酸化增加,但c-Jun氨基末端激酶或p38丝裂原活化蛋白激酶则不会。用包被抗体的乳胶珠来表征特定内皮细胞表面分子在剪切条件下启动信号传导中的作用。我们发现,血管细胞黏附分子-1或E-选择素的连接,而非主要组织相容性复合体I类分子的连接,会在细胞因子刺激的内皮细胞中诱导ERK2磷酸化的剪切依赖性增加。用拉春库林A破坏肌动蛋白细胞骨架可防止在流动条件下黏附后ERK2的磷酸化,这支持了细胞骨架在机械传感中的作用。在相同条件下,粘着斑激酶和桩蛋白会迅速磷酸化,表明粘着斑也参与了机械转导。最后,我们发现Rho相关蛋白激酶和钙蛋白酶在流动条件下嗜酸性粒细胞随后的跨内皮迁移中都起着关键作用。这些数据表明,在流动条件下白细胞黏附分子的连接会导致内皮细胞中的机械转导,进而可调节随后的白细胞运输。