Hagiwara H, Mitsumata M, Yamane T, Jin X, Yoshida Y
Department of Pathology, School of Medicine, Yamanashi Medical University, Yamanashi, Japan.
Circulation. 1998 Dec 8;98(23):2584-90. doi: 10.1161/01.cir.98.23.2584.
The shear stress induced by blood flow may play a pivotal role in the induction or prevention of atherosclerosis by changing endothelial functions. To disclose the mechanisms of this change, we prepared an endothelial cell (EC) cDNA library to select specific clones expressed in response to shear stress.
The mRNA of cultured confluent bovine aortic ECs (BAECs) subjected to steady laminar shear stress (30 dyne/cm2) for 4 hours was separated, and a cDNA library was prepared. Nine clones whose expressions were specifically enhanced by the shear stress were selected by use of a differential hybridization method. One clone had 94% homology at the nucleotide sequence level to Oryctolagus cuniculus gro (GRO) mRNA and 79% homology at the amino acid sequence level to human GRO-beta. The GRO mRNA expression was increased in both BAECs and human umbilical vein ECs (HUVECs) after the ECs were subjected to high (30 dyne/cm2) and low (5 dyne/cm2) laminar shear stress. GRO-alpha and/or -beta protein expression also increased after the HUVECs and BAECs were subjected to shear stress. Because GRO protein has been shown to function as an adhesion factor of monocytes on the surface of ECs, we studied whether shear stress-induced monocyte adhesion was caused by GRO protein expression on ECs. The 4-hour shear stress enhanced monocyte adhesion to ECs by 2.5-fold over control levels, and this enhancement was inhibited by 53% by anti-GRO-alpha antibody.
The present study is the first report that shear stress induced the expression of GRO mRNA and protein in ECs and enhanced the monocyte adhesion on ECs via GRO protein. Further investigations of the functions and participation in atherogenesis of this selected clone may clarify the significance of shear stress on atherogenesis.
血流产生的剪切应力可能通过改变内皮功能在动脉粥样硬化的诱发或预防中起关键作用。为了揭示这种变化的机制，我们制备了一个内皮细胞（EC）cDNA文库，以筛选在剪切应力作用下表达的特定克隆。
分离培养的汇合牛主动脉内皮细胞（BAECs）在稳定层流剪切应力（30达因/平方厘米）作用4小时后的mRNA，并制备cDNA文库。使用差异杂交方法筛选出9个其表达被剪切应力特异性增强的克隆。其中一个克隆在核苷酸序列水平与穴兔GRO（GRO）mRNA有94%的同源性，在氨基酸序列水平与人类GRO-β有79%的同源性。在BAECs和人脐静脉内皮细胞（HUVECs）受到高（30达因/平方厘米）和低（5达因/平方厘米）层流剪切应力作用后，GRO mRNA表达均增加。HUVECs和BAECs受到剪切应力作用后，GRO-α和/或-β蛋白表达也增加。由于GRO蛋白已被证明可作为单核细胞在EC表面的黏附因子，我们研究了剪切应力诱导的单核细胞黏附是否由EC上的GRO蛋白表达引起。4小时的剪切应力使单核细胞对EC的黏附比对照水平增强了2.5倍，而抗GRO-α抗体可使其增强作用降低53%。
本研究首次报道剪切应力可诱导EC中GRO mRNA和蛋白的表达，并通过GRO蛋白增强单核细胞在EC上的黏附。对该筛选克隆的功能及其在动脉粥样硬化发生中的作用进行进一步研究，可能会阐明剪切应力在动脉粥样硬化发生中的意义。
