Co‐expression of p53 and MDM2 in human atherosclerosis: implications for the regulation of cellularity of atherosclerotic lesions
Co‐expression of p53 and MDM2 in human atherosclerosis: implications for the regulation of cellularity of atherosclerotic lesions
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DOI：
10.1002/(sici)1096-9896(199807)185:3
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发表时间：
1998-07
期刊：
影响因子：
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通讯作者：
C. Ihling;J. Haendeler;G. Menzel;R. Hess;G. Fraedrich;H. Schaefer;A. Zeiher
中科院分区：
文献类型：
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作者：
C. Ihling;J. Haendeler;G. Menzel;R. Hess;G. Fraedrich;H. Schaefer;A. Zeiher
动脉粥样硬化是动脉内膜的纤维增生性疾病。最近发现野生型p53 （wt p53）在人类动脉粥样硬化组织中积累。Wt p53是一种细胞周期调节因子，参与DNA修复、DNA合成、细胞分化和凋亡，因此可能对动脉粥样硬化斑块的细胞化起重要作用。MDM2基因的产物是一种与p53形成复合物的核蛋白，从而抑制wt p53对细胞周期进程的负调控作用。为了研究p53与MDM2相互作用在动脉粥样硬化组织中调节细胞结构的潜在作用，研究了22例接受动脉内膜切除术患者的颈动脉粥样硬化斑块，以确定p53免疫反应性（IR）、MDM2 IR、MIB1/Ki‐67 IR证明的细胞增殖以及通过原位转移酶介导的dUTP 3’端标记（TUNEL）作为细胞凋亡标志物的DNA片段的存在。p53 IR定位于有慢性炎症证据的区域（22/22），几乎在所有细胞类型的细胞核（68.79±7.51%）中都观察到。人乳腺内动脉组织的对照细胞中有0.2%±0.29%的细胞呈p53染色（P≤0.002）。所有病例（22/22）的巨噬细胞和平滑肌细胞（SMCs）中均存在MDM2 IR，占细胞核的60.53±8.32%（对照组：0.8%±0.65%,P≤0.002），并通过相邻切片检查和双重免疫荧光标记与p53 IR共定位。重要的是，共免疫沉淀和western blot分析显示，p53和MDM2在物理上是相关的，这表明MDM2 - p53复合物的形成发生在人体内动脉粥样硬化组织中。TUNEL染色和MIB1/Ki‐67 IR阳性存在于3.01±1.27%的细胞核中（对照组：0%，P≤0.002），与p53 IR和MDM2 IR定位于相同的斑块区室。因此，p53积累细胞的命运可能取决于p53和MDM2蛋白的相互作用和化学计量。确实发现细胞具有强烈的p53积累和典型的凋亡核形态，并且有少数MIB1/Ki‐67阳性细胞与MDM2共表达，这表明MDM2可能在逆转p53对细胞周期进程的负调节作用中起作用。p53 IR与MDM2 IR的核共定位以及共免疫沉淀实验表明，在人动脉粥样硬化组织中存在p53 - MDM2复合物的形成。个体p53和MDM2 - co表达细胞的命运是经历p53依赖性凋亡还是重新进入细胞增殖周期，可能取决于这两种蛋白的相对比例。因此，p53和MDM2可能在调节人类动脉粥样硬化斑块的细胞结构和炎症活动中发挥重要作用。©1998 John Wiley & Sons, Ltd
Atherosclerosis is a fibroproliferative disease of the arterial intima. It was recently found that wild‐type p53 (wt p53) accumulates in human atherosclerotic tissue. Wt p53 is a cell cycle regulator involved in DNA repair, DNA synthesis, cell differentiation, and apoptosis and might therefore make an important contribution to the cellularity of atherosclerotic plaques. The product of the MDM2 gene is a nuclear protein which forms a complex with p53, thereby inhibiting the negative regulatory effects of wt p53 on cell cycle progression. In order to address a potential role of the interaction of p53 with MDM2 for the regulation of cellularity in atherosclerotic tissue, 22 carotid atheromatous plaques from patients undergoing endarterectomy were studied to determine the presence of p53 immunoreactivity (IR), MDM2 IR, cell proliferation as evidenced by MIB1/Ki‐67 IR and DNA fragmentation by in situterminal transferase‐mediated dUTP 3′ end labelling (TUNEL), as a marker for apoptosis. p53 IR localized to areas with evidence of chronic inflammation (22/22) and was observed in virtually all cell types in 68·79±7·51 per cent of the nuclei. p53 staining in the control tissue from human internal mammary arteries was present in 0·2±0·29 per cent of the cells (P≤0·002). MDM2 IR was present in all cases (22/22) in macrophages and smooth muscle cells (SMCs) in 60·53±8·32 per cent of the nuclei (controls: 0·8±0·65 per cent, P≤0·002) and co‐localized with p53 IR as shown by examination of adjacent sections and by double immunofluorescence labelling. Importantly, co‐immunoprecipitation and western blot analysis revealed that p53 and MDM2 were physically associated, indicating that MDM2–p53 complex formation takes place in vivoin human atherosclerotic tissue. Positive TUNEL staining and MIB1/Ki‐67 IR present in 3·01±1·27 per cent of the nuclei (controls: 0 per cent, P≤0·002) localized to the same plaque compartments as p53 IR and MDM2 IR. Thus, the fate of cells with p53 accumulation may depend on the interaction and the stoichiometry of the p53 and MDM2 proteins. Cells were indeed found with strong p53 accumulation and nuclear morphology typical for apoptosis and there were a few MIB1/Ki‐67‐positive cells with co‐expression of MDM2, indicating a possible role for MDM2 in reversing the negative regulatory effects of p53 for cell cycle progression. The nuclear co‐localization of p53 IR with MDM2 IR and the co‐immunoprecipitation assay indicate the presence of p53–MDM2 complex formation in vivo in human atherosclerotic tissue. The destiny of individual p53 and MDM2‐co‐expressing cells either to undergo p53‐dependent apoptosis or to re‐enter the cycle of cell proliferation may depend on the relative ratios of the two proteins. p53 and MDM2 may therefore play an important role in regulating cellularity and inflammatory activity in human atherosclerotic plaques. © 1998 John Wiley & Sons, Ltd.