Signaling and Stress Response: Fluid shear stress induces upregulation of COX-2 and PGI_2 release in endothelial cells via a pathway involving PEC AM-1, PI3K, FAK, and p38

摘要

Russell-Puleri S, dela Paz NG, Adams D, Chattopadhyay M, Cancel L, Ebong E, Orr AW, Frangos JA, Tarbell JM. Fluid shear stress induces upregulation of COX-2 and PGI_2 release in endothelial cells via a pathway involving PECAM-1, PI3K, FAK, and p38. Am J Physiol Heart Circ Physiol 312: H485-H500, 2017. First published December 23, 2016; doi:10.1152/ajpheart.00035.2016.—Vascular en-dothelial cells play an important role in the regulation of vascular function in response to mechanical stimuli in both healthy and diseased states. Prostaglandin I_2 (PGI_2) is an important antiathero-genic prostanoid and vasodilator produced in endothelial cells through the action of the cyclooxygenase (COX) isoenzymes COX-1 and COX-2. However, the mechanisms involved in sustained, shear-induced production of COX-2 and PGI_2 have not been elucidated but are determined in the present study. We used cultured endothelial cells exposed to steady fluid shear stress (FSS) of 10 dyn/cm~2 for 5 h to examine shear stress-induced induction of COX-2/PGI_2. Our results demonstrate the relationship between the mechanosensor platelet endothelial cell adhesion molecule-1 (PECAM-1) and the intracellular mechanoresponsive molecules phosphatidylinositol 3-kinase (PI3K), focal adhesion kinase (FAK), and mitogen-activated protein kinase p38 in the FSS induction of COX-2 expression and PGI2 release. Knockdown of PECAM-1 (small interference RNA) expression inhibited FSS-induced activation of alpha_5beta_1-integrin, upregulation of COX-2, and release of PGI_2 in both bovine aortic endothelial cells (BAECs) and human umbilical vein endothelial cells (HUVECs). Furthermore, inhibition of the PI3K pathway (LY294002) substantially inhibited FSS activation of alpha_5beta_1-integrin, upregulation of COX-2 gene and protein expression, and release of PGI_2 in BAECs. Inhibition of integrin-associated FAK (PF573228) and MAPK p38 (SB203580) also inhibited the shear-induced upregulation of COX-2. Finally, a PECAM-1 ~-/- mouse model was characterized by reduced COX-2 immunostaining in the aorta and reduced plasma PGI_2 levels compared with wild-type mice, as well as complete inhibition of acute flow-induced PGI_2 release compared with wild-type animals. NEW & NOTEWORTHY In this study we determined the major mechanotransduction pathway by which blood flow-driven shear stress activates cyclooxygenase-2 (COX-2) and prostaglandin I_2 (PGI_2) release in endothelial cells. Our work has demonstrated for the first time that COX-2/PGI_2 mechanotransduction is mediated by the mechanosensor platelet endothelial cell adhesion mole-cule-1 (PECAM-1).