Kluger M S, Johnson D R, Pober J S
Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, CT 06536-0812, USA.
J Immunol. 1997 Jan 15;158(2):887-96.
Persistent E-selectin expression has been proposed to be a unique property of dermal vascular endothelium that directs skin-specific homing of a subpopulation of circulating memory T cells. We compared the kinetics of E-selectin expression on cultured human dermal microvascular endothelial cells (HDMEC) with expression on HUVEC. Following treatment with TNF, E-selectin on HDMEC appears more slowly than on HUVEC (peak values 6-8 vs 4 h, respectively) and is sustained at significantly higher levels after 24 h. E-selectin mRNA, analyzed by S1 nuclease protection, consists of a single predominant transcript that follows a similarly transient time course in both cell types. Cell surface E-selectin is internalized more slowly on HDMEC than on HUVEC (t1/2 = 4.3 vs 1.6 h, respectively) as measured by serial FACS analyses in the presence of the protein synthesis inhibitor cycloheximide. In comparison, intercellular adhesion molecule-1 (ICAM-1) expression is not measurably reduced by either cell type under the same conditions. HDMEC are similar to HUVEC in rates of pinocytosis or receptor-mediated endocytosis. Pulse-chase analysis indicated that the degradative half-life of E-selectin protein is greater in HDMEC than in HUVEC (1.9 vs 1.5 h, respectively). E-selectin internalization in microvascular endothelial cells (EC) from lung and subcutaneous fat is slow, like HDMEC, whereas internalization in large vessel EC from saphenous vein and aorta is rapid, like HUVEC. We conclude that HDMEC sustain higher levels of expression at 24 h by slower internalization and degradation of E-selectin protein and that this may be a general property of microvascular EC.
持续表达E选择素被认为是真皮血管内皮细胞的一个独特特性，它可引导循环记忆T细胞亚群的皮肤特异性归巢。我们比较了培养的人真皮微血管内皮细胞（HDMEC）与脐静脉内皮细胞（HUVEC）上E选择素表达的动力学。用肿瘤坏死因子（TNF）处理后，HDMEC上的E选择素出现得比HUVEC慢（峰值分别为6 - 8小时和4小时），并且在24小时后维持在显著更高的水平。通过S1核酸酶保护分析的E选择素mRNA由单一主要转录本组成，在两种细胞类型中都遵循类似的短暂时间进程。通过在蛋白质合成抑制剂环己酰亚胺存在下进行系列荧光激活细胞分选（FACS）分析测量，HDMEC上细胞表面E选择素的内化比HUVEC慢（半衰期分别为4.3小时和1.6小时）。相比之下，在相同条件下，两种细胞类型的细胞间黏附分子-1（ICAM-1）表达均未出现可测量的减少。HDMEC在胞饮作用或受体介导的内吞作用速率方面与HUVEC相似。脉冲追踪分析表明，E选择素蛋白在HDMEC中的降解半衰期比在HUVEC中更长（分别为1.9小时和1.5小时）。肺和皮下脂肪的微血管内皮细胞（EC）中E选择素的内化较慢，类似于HDMEC，而大隐静脉和主动脉的大血管EC中的内化较快，则类似于HUVEC。我们得出结论，HDMEC通过E选择素蛋白较慢的内化和降解在24小时维持较高水平的表达，并且这可能是微血管EC的一个普遍特性。
