Rajagopalan V, Essex D W, Shapiro S S, Konkle B A
Cardeza Foundation for Hematologic Research, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107.
Blood. 1992 Jul 1;80(1):153-61.
Glycoprotein Ib alpha (GpIb alpha) is a platelet membrane Gp that binds von Willebrand factor and mediates platelet adhesion to subendothelium. We have found both GpIb alpha mRNA and protein in human umbilical vein endothelial cells (HUVEC). In previously published work we reported that combined treatment with interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) markedly increased the GpIb alpha mRNA level in HUVEC. We have now documented that TNF-alpha alone induces GpIb alpha mRNA and protein expression, studied the kinetics of this response, and investigated potential mechanisms of the TNF-alpha effect. GpIb alpha mRNA induction by TNF-alpha is detectable as early as 2 hours after exposure to this cytokine, and reaches a maximal level after 20 to 24 hours. Using a nuclear run-on assay we found that GpIb alpha gene transcription is increased approximately 10-fold after 2 hours of TNF-alpha treatment. Furthermore, using two monoclonal antibodies that recognize different epitopes of GpIb alpha, we found that the protein expression in endothelial cells is markedly increased by TNF-alpha. Interleukin-1 (IL-1) and the phorbol ester phorbol myristate acetate, which mimic many effects of TNF-alpha on endothelial cells, have no effect on endothelial or human erytholeukemia (HEL)-cell GpIb alpha mRNA. TNF-alpha treatment for 24 hours increases the HEL cell GpIb alpha mRNA level approximately fourfold, showing a time- and dose-dependent effect similar to that seen in HUVEC. TNF-alpha-induced GpIb alpha mRNA and protein synthesis may play a role in mediating platelet or other cell interaction with activated endothelium. Unlike other endothelial pro-thrombotic and pro-adhesive proteins induced by TNF-alpha, GpIb alpha is not induced by IL-1 treatment, which suggests a novel pathway for induction of this protein.
糖蛋白 Ibα（GpIbα）是一种血小板膜糖蛋白，它能结合血管性血友病因子并介导血小板与内皮下层的黏附。我们在人脐静脉内皮细胞（HUVEC）中发现了 GpIbα 信使核糖核酸（mRNA）和蛋白质。在之前发表的研究中，我们报道了干扰素 -γ（IFN -γ）和肿瘤坏死因子 -α（TNF -α）联合处理能显著提高 HUVEC 中 GpIbα mRNA 的水平。我们现在已证明，单独使用 TNF -α 就能诱导 GpIbα mRNA 和蛋白质表达，研究了这种反应的动力学，并探讨了 TNF -α 作用的潜在机制。TNF -α 诱导 GpIbα mRNA 最早在接触该细胞因子 2 小时后就能检测到，20 至 24 小时后达到最高水平。通过核转录分析，我们发现 TNF -α 处理 2 小时后，GpIbα 基因转录增加了约 10 倍。此外，使用两种识别 GpIbα 不同表位的单克隆抗体，我们发现 TNF -α 能显著增加内皮细胞中的蛋白质表达。白细胞介素 -1（IL -1）和佛波酯肉豆蔻酸佛波醇酯，它们模拟了 TNF -α 对内皮细胞的许多作用，但对内皮细胞或人红白血病（HEL）细胞的 GpIbα mRNA 没有影响。TNF -α 处理 24 小时可使 HEL 细胞 GpIbα mRNA 水平增加约四倍，显示出与 HUVEC 中相似的时间和剂量依赖性效应。TNF -α 诱导的 GpIbα mRNA 和蛋白质合成可能在介导血小板或其他细胞与活化内皮细胞的相互作用中发挥作用。与 TNF -α 诱导的其他内皮促血栓形成和促黏附蛋白不同，IL -1 处理不会诱导 GpIbα，这提示了诱导该蛋白的一条新途径。
