Egr-1, PKC Beta, Signalling and Atherosclerosis

描述（由申请人提供）：直接早期基因，早期生长反应-1 (egr-1)，与急性细胞扰动设置下的适应性不良宿主反应机制有关。除了急性应激外，egr-1的上调可能与慢性血管应激有关。与邻近的非动脉粥样硬化斑块相比，人类和小鼠动脉粥样硬化病变中egr-1的转录本均上调，从而表明egr-1对血管应激的影响可能不限于急性环境，而是可能影响慢性血管扰动，如动脉粥样硬化。我们的初步研究支持这一概念，因为实时PCR显示时间依赖性。在6、8、10、14和24周龄时，载脂蛋白E(0)小鼠与C57BL/6对照组相比，主动脉中egr-1转录物增加。免疫组化结果显示，动脉粥样硬化中表达egr-1的细胞主要为单核吞噬细胞（MP）和平滑肌细胞（SMC）。在载脂蛋白E (apo E)(0)背景下，纯合子egr-1(0)小鼠在14或24周龄时，与载脂蛋白E(0)动物相比，主动脉根部动脉粥样硬化明显减少。与此同时，促炎和促凝介质如JE/MCP- 1、il -1 β、VCAM-1、ICAM-1、组织因子（TF）和PAI-1的转录本在双鼠(0)中与单纯缺载脂蛋白E(0)的小鼠相比显著减少。为了测试急性缺氧中egr-1的上游关键调节因子PKCbeta轴是否在慢性血管应激中调节egr-1的调节，我们将纯合子PKCbeta(0)小鼠培养到载脂蛋白E(0)背景中。PKCbeta (0)/apo E(0)小鼠与apo E(0)小鼠相比，24周龄时动脉粥样硬化病变面积明显减少。血浆葡萄糖和胆固醇/甘油三酯水平在egr-1(0)-或PKCbeta(0)/载脂蛋白E(0)小鼠与载脂蛋白E(0)动物之间没有差异，因此暗示egr-1和PKCbeta是动脉粥样硬化的不同方面。我们假设pkcβ依赖性的egr-1上调对加速血管壁的促炎和血栓形成机制起重要作用；与动脉粥样硬化发病机制相关的过程。我们建议剖析pkcβ和egr-1在高胆固醇血症载脂蛋白E(0)小鼠中促进病变发展/进展的生化和信号机制，并期望阐明这些因素影响动脉粥样硬化形成的机制可能会为治疗干预提供新的靶点。

DESCRIPTION (provided by applicant): The immediate early gene, early growth response-1 (egr-1), is linked to maladaptive host response mechanisms m settings of acute cellular perturbation. In addition to acute stress, up regulation of egr-1 may be linked to chronic vascular stress. Transcripts for egr-1 were up regulated in both human and murine atherosclerotic lesions compared to adjacent non-atheromatous plaque, thereby suggesting that the impact of egr-1 in vascular stress might not be limited to the acute setting, rather that egr-1 might impact on chronic vascular perturbation, such as atherosclerosis. Our preliminary studies support this concept, as real time PCR revealed a time-dependent .increase in egr-1 transcripts in aortae of apo E (0) mice versus C57BL/6 controls at ages 6, 8, 10, 14 & 24 weeks. Immunohistochemistry demonstrated that the principal egr-1 expressing cells in atheromata were mononuclear phagocytes (MP) and smooth muscle cells (SMC). Homozygous egr-1 (0) mice in the apolipoprotein E (apo E) (0) background displayed significantly reduced atherosclerosis at the aortic root compared with apo E (0) animals at 14 or 24 weeks of age. In parallel, transcripts for proinflammatory & procoagulant mediators such as JE/MCP- 1, IL-1beta, VCAM-1, ICAM-1, tissue factor (TF) and PAI-1 were significantly diminished in double (0) mice versus mice solely deficient in apo E (0). To test if the PKCbeta axis, a key upstream regulator of egr-1 in acute hypoxia, modulated regulation of egr-1 in chronic vascular stress, we bred homozygous PKCbeta (0) mice into the apo E (0) background. A striking decrease in atherosclerotic lesion area was evident at age 24 weeks in PKCbeta (0)/apo E (0) vs apo E (0) mice. Levels of plasma glucose and cholesterol/triglyceride did not differ between egr- 1 (0)- or PKCbeta (0)/apo E (0) mice versus apo E (0) animals, thus implicating egr-1 and PKCbeta as distinct facets in atherosclerosis. We hypothesize that PKCbeta-dependent up regulation of egr-1 contributes importantly to acceleration of proinflammatory and prothrombotic mechanisms in the vessel wall; processes linked to the pathogenesis of atherosclerosis. We propose to dissect the biochemical and signaling mechanisms by which PKCbeta and egr-1 contribute to lesion development/progression in hypercholesterolemic apo E (0) mice and anticipate that elucidation of the mechanisms by which these factors impact on atherogenesis may highlight new targets for therapeutic intervention.