Ali Mir H, Pearlstein Daryl P, Mathieu Carol E, Schumacker Paul T
Am J Physiol Lung Cell Mol Physiol. 2004 Sep;287(3):L486-96. doi: 10.1152/ajplung.00389.2003. Epub 2004 Apr 16.
Mechanical strain triggers a variety of cellular responses, but the underlying mechanotransduction process has not been established. Endothelial cells (EC) respond to mechanical strain by upregulating adhesion molecule expression through a signaling process involving reactive oxygen species (ROS), but the site of their generation is unknown. Mitochondria anchor to the cytoskeleton and could function as mechanotransducers by releasing ROS during cytoskeletal strain. In human umbilical vein EC (HUVEC), ROS production increased 221 +/- 17% during 6 h of cyclic strain vs. unstrained controls. Mitochondrial inhibitors diphenylene iodonium or rotenone abrogated this response, whereas inhibitors of nitric oxide (NO) synthase (L-nitroarginine), xanthine oxidase (allopurinol), or NAD(P)H oxidase (apocynin) had no effect. The antioxidants ebselen and diethyldithiocarbamate inhibited the increase in ROS, but the NO scavenger Hb had no effect. Thus strain induces ROS release from mitochondria. In other studies, HUVEC were rendered mitochondria deficient (rho0 EC) to determine the requirement for electron transport in the response to strain. Strain-induced 2'7'-dichlorofluorescein fluorescence was attenuated by >80% in rho0 EC compared with HUVEC (43 +/- 7 vs. 221 +/- 17%). Treatment with cytochalasin D abrogated strain-induced ROS production, indicating a requirement for the actin cytoskeleton. Cyclic strain (6 h) increased VCAM-1 expression in wild-type but not rho0 EC. Increases in NF-kappaB activation and VCAM-1 mRNA expression during strain were prevented by antioxidants. These findings demonstrate that mitochondria function as mechanotransducers in endothelium by increasing ROS signaling, which is required for strain-induced increase in VCAM-1 expression via NF-kappaB.
机械应变会引发多种细胞反应，但潜在的机械转导过程尚未明确。内皮细胞（EC）通过涉及活性氧（ROS）的信号传导过程上调黏附分子表达来响应机械应变，但其产生部位尚不清楚。线粒体锚定在细胞骨架上，可能通过在细胞骨架应变期间释放ROS发挥机械转导作用。在人脐静脉内皮细胞（HUVEC）中，与未受应变的对照相比，在6小时的循环应变期间ROS产生增加了221±17%。线粒体抑制剂二苯基碘鎓或鱼藤酮消除了这种反应，而一氧化氮（NO）合酶抑制剂（L-硝基精氨酸）、黄嘌呤氧化酶抑制剂（别嘌呤醇）或NAD（P）H氧化酶抑制剂（夹竹桃麻素）则没有效果。抗氧化剂依布硒啉和二乙基二硫代氨基甲酸盐抑制了ROS的增加，但NO清除剂血红蛋白没有效果。因此，应变诱导线粒体释放ROS。在其他研究中，使HUVEC线粒体缺陷（rho0 EC）以确定电子传递在应变反应中的需求。与HUVEC相比，rho0 EC中应变诱导的2'7'-二氯荧光素荧光减弱了>80%（43±7对221±17%）。用细胞松弛素D处理消除了应变诱导的ROS产生，表明肌动蛋白细胞骨架是必需的。循环应变（6小时）增加了野生型而非rho0 EC中VCAM-1的表达。抗氧化剂可防止应变期间NF-κB激活和VCAM-1 mRNA表达的增加。这些发现表明，线粒体通过增加ROS信号传导在内皮中发挥机械转导作用，而ROS信号传导是应变通过NF-κB诱导VCAM-1表达增加所必需的。
