Identification of histone H2B as a regulated plasminogen receptor
Identification of histone H2B as a regulated plasminogen receptor
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DOI：
10.1021/bi060756w
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发表时间：
2006-08-08
期刊：
影响因子：
2.9
通讯作者：
Plow, Edward F.
中科院分区：
文献类型：
--
作者：
Herren, Thomas;Burke, Timothy A.;Plow, Edward F.
纤溶酶原拴在细胞表面控制纤溶酶的形成，从而影响细胞周蛋白水解和细胞迁移。细胞纤溶酶原结合位点的调节为这些事件的调控提供了一种机制。在这项研究中，研究了两种不同的模型，即phorbol酯刺激的U937单核细胞粘附和外周血中性粒细胞的培养，这些处理可以调节纤溶酶原结合位点，以确定纤溶酶原受体上调的分子基础。从有或没有上调纤溶酶原结合能力的细胞群中分离出膜，并通过凝胶转移的[I-125]纤溶酶原配体印迹分析。在膜组分中发现了大约15种不同的[I-125]纤溶酶原结合蛋白，并且在不同的细胞群中只注意到单个条带强度的相对较小差异。值得注意的例外是存在一个17 kDa的条带，该条带在具有增强纤溶酶原结合能力的细胞的膜中选择性地显着增强。从两种细胞类型中分离出17kda蛋白，肽片段的氨基酸测序鉴定出相同的蛋白，组蛋白H2B。通过共聚焦显微镜观察，在刺激的U937细胞和培养的中性粒细胞上，组蛋白H2B的羧基端八肽序列抗体升高，组蛋白H2B表达增加。该抗体或其Fab片段大大降低了纤溶酶原与培养的中性粒细胞的结合水平，并刺激了U937细胞，其结合水平升高，但未刺激细胞则没有。因此，组蛋白H2B代表了一种受调控的纤溶酶原受体，它对细胞的纤溶酶原结合能力有重要贡献。
Tethering of plasminogen to cell surfaces controls plasmin formation and, thereby, influences pericellular proteolysis and cell migration. Modulation of cellular plasminogen binding sites provides a mechanism for regulation of these events. In this study, two distinct models, phorbol ester-stimulated adhesion of U937 monocytoid cells and culturing of peripheral blood neutrophils, treatments which modulate plasminogen binding sites, have been examined to determine the molecular basis for the upregulation of plasminogen receptors. Membranes were isolated from cell populations, with and without upregulated plasminogen binding capacities, and analyzed by [I-125] plasminogen ligand blotting of gel transfers. Approximately 15 different [I-125] plasminogen-binding proteins were discerned in the membrane fractions, and only relatively minor differences in the intensities of individual bands were noted in the different cell populations. The notable exception was the presence of a 17 kDa band, which was selectively and markedly enhanced in the membranes from cells with enhanced plasminogen binding capacities. The 17 kDa protein was isolated from both cell types, and amino acid sequencing of peptide fragments identified the same protein, histone H2B. Increased expression of histone H2B was observed on stimulated U937 cells and cultured neutrophils by confocal microscopy with an antibody raised to the carboxy-terminal octopeptide sequence of histone H2B. This antibody or its Fab fragments substantially decreased the level of binding of plasminogen to these cultured neutrophils and stimulated U937 cells that exhibited elevated levels of binding but not to nonstimulated cells. Thus, histone H2B represents a regulated plasminogen receptor, which contributes significantly to the plasminogen binding capacity of cells.