Molecular mechanisms of atherogenesis

动脉粥样硬化形成的分子机制

基本信息

批准号：
08407026
负责人：
KITA Tooru
金额：
$ 25.47万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

Endothelial dysfunction, or activation, elicited by oxidized low density lipoprotein (Ox-LDL) or its lipid constituent has been implicated in the pathogenesis of atherosclerosis. Lysophosphatidylcholine (lyso-PC), a phospholipid component of Ox-LDL, has been shown to induce expression of endothelial-leukocyte adhesion molecules, such as VCAM-1 and ICAM-1, and smooth muscle growth factors, including PDGF A and B chains and HB-EGF, which appear to play crucial roles in recruitment of circulating monocytes and T-lymphocytes into atherosclerotic lesions and migration and proliferation of medical smooth muscle cells into atherosclerotic intima.One of the aims of our studies is to define transcriptional and signal transduction mechanisms involved in lyso-PC-induced gene expression. We have found that elevated levels of intracellular cyclic AMP inhibited lyso-PC-induced expression of PDGF and ICAM-1: Furthermore, lyso-PC-induced expression of PDGF was dependent upon protein tyrosine phosphory … More lation. We, Therefore, explored the protein that can rapidly phosphorylated in the tyrosine residue. We have revealed that a protein with a molecular mass of 130kDa, which was designated p130, was rapidly and transiently tyrosine-phosphorylated by lyso-PC. By use of immunoblotting and immunoprecipitation, we have identified p130 as PECAM-1 which was expressed on the intercellular junction of cultured endothelial cells. Our study also have demonstrated that MAP kinases, such as ERK and JNK, were activated by lyso-PC, which appeared to depend upon protein tyrosine phosphorylation. Taken together, tyrosine phosphorylation of PECAM-1 may be the upstream of MAP kinase activation by lyso-PC.On the other hand, vascular endothelial cells can take up Ox-LDL via receptor-dmediated endocytosis. Our recent studied have identified, for the first time, a receptor for Ox-LDL expressed in the cell-surface of vascular endothelial cells. By immunoblotting and Northern blotting, we have found that expression of LOX-1 can be upregulated by an inflammatory cytokine TNF-α and laminar flow fluid shear stress. Nuclear run-off assays have revealed that TNF-α and flow fluid shear stress can stimulate transcription of LOX-1 gene. Unregulated expression of LOX-1 by TNF-α was associated a cell line which stably expresses LOX-1 on the cell-surface. By use of this cell line, we have found that LOX-1 can bind, internalize, and degrade Ox-LDL but not significantly acetylated LDL. Binding and degradation of Ox-LDL by LOX-1 was suppressed by reagents, such as polyinosinic acid and carageenan. In contrast, fucoidin and maleylated serum albumin, which had been shown to inhibit Ox-LDL binding and degradation by class A macrophage scavenger receptors, did not significantly inhibit Ox-LDL binding or degradation by LOX-1. Delipidation of Ox-LDL did not affect the ability to bind LOX-1; therefore, protein portion of Ox-LDL particles appeared to be the ligand of LOX-1. These results, thus, indicated that ligand specificity of LOX-1 is different from that of class A or B scavenger receptors. Less

氧化低密度脂蛋白 (Ox-LDL) 或其脂质成分引起的内皮功能障碍或激活与动脉粥样硬化的发病机制有关，溶血磷脂酰胆碱 (lyso-PC) 是 Ox-LDL 的磷脂成分，已被证明可诱导动脉粥样硬化。内皮白细胞粘附分子（例如 VCAM-1 和 ICAM-1）以及平滑肌生长因子（包括 PDGF A）的表达B 链和 HB-EGF，它们似乎在将循环单核细胞和 T 淋巴细胞募集到动脉粥样硬化病变以及医学平滑肌细胞迁移和增殖到动脉粥样硬化内膜中发挥着至关重要的作用。我们研究的目的之一是定义转录以及参与 lyso-PC 诱导的基因表达的信号转导机制我们发现细胞内环 AMP 水平升高会抑制 lyso-PC 诱导的 PDGF 和 ICAM-1 表达：此外， lyso-PC 诱导的 PDGF 表达依赖于蛋白质酪氨酸磷酸化，因此，我们探索了能够在酪氨酸残基中快速磷酸化的蛋白质，并将其命名为分子量为 130kDa 的蛋白质。 p130 被 lyso-PC 快速、短暂地酪氨酸磷酸化通过使用免疫印迹和免疫沉淀，我们已将 p130 鉴定为PECAM-1 在培养的内皮细胞的细胞间连接处表达，我们的研究还表明 MAP 激酶（例如 ERK 和 JNK）可以被 lyso-PC 激活，这似乎依赖于蛋白质酪氨酸磷酸化。 PECAM-1的磷酸化可能是lyso-PC激活MAP激酶的上游。另一方面，血管内皮细胞可以通过我们最近的研究首次鉴定了血管内皮细胞细胞表面表达的 Ox-LDL 受体，通过免疫印迹和 Northern 印迹，我们发现 LOX-1 的表达可以通过受体介导的内吞作用进行。炎症细胞因子 TNF-α 和层流流体剪切应力上调。核径流测定表明 TNF-α 和流动流体剪切应力可以刺激 LOX-1 基因的转录。 LOX-1 与 TNF-α 相关联，该细胞系在细胞表面稳定表达 LOX-1。通过使用该细胞系，我们发现 LOX-1 可以结合、内化和降解 Ox-LDL，但不能。 LOX-1 显着乙酰化的 LDL 被聚肌苷酸和角叉菜胶等试剂抑制，而岩藻多糖和马来酰化血清白蛋白则被抑制。表明可抑制 A 类巨噬细胞清道夫受体的 Ox-LDL 结合和降解，但不会显着抑制 LOX-1 的 Ox-LDL 结合或降解，因此 Ox-LDL 的脱脂不影响结合 LOX-1 的能力； Ox-LDL 颗粒的一部分似乎是 LOX-1 的配体，因此，这些结果表明 LOX-1 的配体特异性与 A 类或 B 类清道夫受体不同。

项目成果

期刊论文数量（50）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Hiroshi Ochi,Noriaki Kume,et al: "Tyrosine phosphorylation on of platelet endothelial cell adhesion molecule-1 induced by lysophosphatidylcholine in cultured endothelial cells"Biochem.Biophys,Res.Commun. vol.243. 862-868 (1998)

Hiroshi Ochi、Noriaki Kume 等人：“培养的内皮细胞中溶血磷脂酰胆碱诱导的血小板内皮细胞粘附分子-1 的酪氨酸磷酸化”Biochem.Biophys，Res.Commun。

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Eiichiro Nishi,Noriaki Kume,et al: "Lysophosphatidylcholine enhances cytokine-induced interferon gamma expression in human T lymphocytes"Circulation Research. vol.83. 508-515 (1998)

Eiichiro Nishi，Noriaki Kume，等人：“溶血磷脂酰胆碱增强人T淋巴细胞中细胞因子诱导的干扰素γ表达”循环研究。

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Nishioka,H.: "Lysophosphatidylcholine generates superoxide anios through activation of phosphatidylinositol 3-kinase in human neutrophils." FEBS lett.

Nishioka, H.：“溶血磷脂酰胆碱通过激活人中性粒细胞中的磷脂酰肌醇 3-激酶产生超氧化物阴离子。”

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Uematsu,M.et al.: "Coexistent myelodysplastic syndrome and non-Hodgkin lymphoma. Report of a case and review of the literature." Int.J.Hematology. 62. 45-51 (1995)

Uematsu,M.et al.：“骨髓增生异常综合征与非霍奇金淋巴瘤共存。病例报告及文献综述。”

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Hideaki Moriwaki, Noriaki Kume, Tatsuya Sawamura, Takuma Aoyama, Hajime Hoshikawa, Hiroshi Ochi, Eiichiro Nishi, Tomoh Masaki, Toru Kita: "Ligand specificity of lOX-1, a novel endothelial receptor for oxidized low density lipoprotein."Arterioscler.Thromb.

Hideaki Moriwaki、Noriaki Kume、Tatsuya Sawamura、Takuma Aoyama、Hajime Hoshikawa、Hiroshi Ochi、Eiichiro Nishi、Tomoh Masaki、Toru Kita：“lOX-1 的配体特异性，氧化低密度脂蛋白的一种新型内皮受体。”动脉硬化器。血栓。