Division of Cardiology, Department of Medicine, State University of New York, Downstate Medical Center, Brooklyn, New York 11203, USA.
J Transl Med. 2011 Jun 26;9:98. doi: 10.1186/1479-5876-9-98.
The F11 Receptor (F11R; aka JAM-A, JAM-1) is a cell adhesion protein present constitutively on the membrane surface of circulating platelets and within tight junctions of endothelial cells (ECs). Previous reports demonstrated that exposure of ECs to pro-inflammatory cytokines causes insertion of F11R molecules into the luminal surface of ECs, ensuing with homologous interactions between F11R molecules of platelets and ECs, and a resultant adhesion of platelets to the inflamed ECs. The main new finding of the present report is that the first step in this chain of events is the de-novo transcription and translation of F11R molecules, induced in ECs by exposure to inflammatory cytokines.
The experimental approach utilized isolated, washed human platelet suspensions and cultured human venous endothelial cells (HUVEC) and human arterial endothelial cells (HAEC) exposed to the proinflammatory cytokines TNF-alpha and/or IFN-gamma, for examination of the ability of human platelets to adhere to the inflamed ECs thru the F11R. Our strategy was based on testing the effects of the following inhibitors on this activity: general mRNA synthesis inhibitors, inhibitors of the NF-kappaB and JAK/STAT pathways, and small interfering F11R-mRNA (siRNAs) to specifically silence the F11R gene.
Treatment of inflamed ECs with the inhibitors actinomycin, parthenolide or with AG-480 resulted in complete blockade of F11R- mRNA expression, indicating the involvement of NF-kappaB and JAK/STAT pathways in this induction. Transfection of ECs with F11R siRNAs caused complete inhibition of the cytokine-induced upregulation of F11R mRNA and inhibition of detection of the newly- translated F11R molecules in cytokine-inflamed ECs. The functional consequence of the inhibition of F11R transcription and translation was the significant blockade of the adhesion of human platelets to inflamed ECs.
These results prove that de novo synthesis of F11R in ECs is required for the adhesion of platelets to inflamed ECs. Because platelet adhesion to an inflamed endothelium is crucial for plaque formation in non-denuded blood vessels, we conclude that the de-novo translation of F11R is a crucial early step in the initiation of atherogenesis, leading to atherosclerosis, heart attacks and stroke.
F11 受体（F11R；又名 JAM-A、JAM-1）是一种细胞黏附蛋白，在循环血小板的膜表面和内皮细胞（EC）的紧密连接处持续存在。先前的报告表明，EC 暴露于促炎细胞因子会导致 F11R 分子插入 EC 的腔表面，随后血小板和 EC 之间的 F11R 分子发生同源相互作用，导致血小板黏附于发炎的 EC。本报告的主要新发现是，这一连串事件的第一步是在细胞因子刺激下，EC 中 F11R 分子的新转录和翻译。
本实验采用分离、洗涤的人血小板悬液和培养的人静脉内皮细胞（HUVEC）和人动脉内皮细胞（HAEC），研究促炎细胞因子 TNF-α和/或 IFN-γ刺激后，人血小板通过 F11R 黏附于发炎 EC 的能力。我们的策略基于以下抑制剂对该活性的影响进行测试：通用 mRNA 合成抑制剂、NF-κB 和 JAK/STAT 途径抑制剂以及针对 F11R 基因的小干扰 RNA（siRNAs）。
用放线菌素、紫衫内酯或 AG-480 处理发炎的 EC 会导致 F11R-mRNA 表达完全阻断，表明 NF-κB 和 JAK/STAT 途径参与了这种诱导。用 F11R siRNAs 转染 EC 会导致细胞因子诱导的 F11R mRNA 上调完全抑制，并抑制在细胞因子发炎的 EC 中检测到新翻译的 F11R 分子。F11R 转录和翻译抑制的功能后果是显著阻止了人血小板与发炎的 EC 黏附。
这些结果证明了 EC 中 F11R 的从头合成对于血小板与发炎的 EC 黏附是必需的。由于血小板黏附于发炎的内皮细胞对于非裸露血管中的斑块形成至关重要，因此我们得出结论，F11R 的从头翻译是动脉粥样硬化形成、导致动脉粥样硬化、心脏病发作和中风的起始的关键早期步骤。
