Chess Patricia R, O'Reilly Michael A, Sachs Fredrick, Finkelstein Jacob N
Department of Pediatrics, University of Rochester, New York, USA.
J Appl Physiol (1985). 2005 Sep;99(3):1226-32. doi: 10.1152/japplphysiol.01105.2004. Epub 2005 May 12.
Mechanical strain is necessary for normal lung growth and development. Individuals with respiratory failure are supported with mechanical ventilation, leading to altered lung growth and injury. Understanding signaling pathways initiated by mechanical strain in lung epithelial cells will help guide development of strategies aimed at optimizing strain-induced lung growth while mitigating ventilator-induced lung injury. To study strain-induced proliferative signaling, focusing on the role of reactive oxidant species (ROS) and p42/44 mitogen-activated protein (MAP) kinase, human pulmonary epithelial H441 and MLE15 cells were exposed to equibiaxial cyclic mechanical strain. ROS were increased within 15 min of strain. N-acetylcysteine inactivated strain-induced ROS and inhibited p42/44 MAP kinase phosphorylation and strain-induced proliferation. PD98059 and UO126, p42/44 MAP kinase inhibitors, blocked strain-induced proliferation. To verify the specificity of p42/44 MAP kinase inhibition, cells were transfected with dominant-negative mitogen-activated protein kinase kinase-1 plasmid DNA. Transfected cells did not proliferate in response to mechanical strain. To determine whether strain-induced tyrosine kinase activity is necessary for strain-induced ROS-p42/44 MAP kinase signaling, genistein, a tyrosine kinase inhibitor, was used. Genistein did not block strain-induced ROS production or p42/44 MAP kinase phosphorylation. Gadolinium, a mechanosensitive calcium channel blocker, blocked strain-induced ROS production and p42/44 MAP kinase phosphorylation but not strain-induced tyrosine phosphorylation. These data support ROS production and p42/44 MAP kinase phosphorylation being involved in a common strain-induced signaling pathway, necessary for strain-induced proliferation in pulmonary epithelial cells, with a parallel strain-induced tyrosine kinase pathway.
机械牵张对于正常肺的生长和发育是必需的。呼吸衰竭患者通过机械通气来维持生命，这会导致肺生长改变和肺损伤。了解肺上皮细胞中由机械牵张引发的信号通路，将有助于指导制定策略，以优化牵张诱导的肺生长，同时减轻呼吸机诱导的肺损伤。为了研究牵张诱导的增殖信号，重点关注活性氧（ROS）和p42/44丝裂原活化蛋白（MAP）激酶的作用，将人肺上皮H441和MLE15细胞暴露于等轴循环机械牵张中。牵张后15分钟内ROS增加。N-乙酰半胱氨酸使牵张诱导的ROS失活，并抑制p42/44 MAP激酶磷酸化和牵张诱导的增殖。p42/44 MAP激酶抑制剂PD98059和UO126阻断了牵张诱导的增殖。为了验证p42/44 MAP激酶抑制的特异性，用显性负性丝裂原活化蛋白激酶激酶-1质粒DNA转染细胞。转染后的细胞对机械牵张无增殖反应。为了确定牵张诱导的酪氨酸激酶活性对于牵张诱导的ROS-p42/44 MAP激酶信号传导是否必要，使用了酪氨酸激酶抑制剂染料木黄酮。染料木黄酮未阻断牵张诱导的ROS产生或p42/44 MAP激酶磷酸化。机械敏感钙通道阻滞剂钆阻断了牵张诱导的ROS产生和p42/44 MAP激酶磷酸化，但未阻断牵张诱导的酪氨酸磷酸化。这些数据支持ROS产生和p42/44 MAP激酶磷酸化参与了一条共同的牵张诱导信号通路，该通路是肺上皮细胞牵张诱导增殖所必需的，同时存在一条平行的牵张诱导酪氨酸激酶通路。
