Blanco Francisco J, Grande María T, Langa Carmen, Oujo Barbara, Velasco Soraya, Rodriguez-Barbero Alicia, Perez-Gomez Eduardo, Quintanilla Miguel, López-Novoa Jose M, Bernabeu Carmelo
Centro de Investigaciones Biologicas, Consejo Superior de Investigaciones Cientificas, Madrid, Spain.
Circ Res. 2008 Dec 5;103(12):1383-92. doi: 10.1161/CIRCRESAHA.108.176552. Epub 2008 Oct 30.
Senescence of endothelial cells (ECs) may contribute to age-associated cardiovascular diseases, including atherosclerosis and hypertension. The functional and gene expression changes associated with cellular senescence are poorly understood. Here, we have analyzed the expression, during EC senescence, of 2 different isoforms (L, long; S, short) of endoglin, an auxiliary transforming growth factor (TGF)-beta receptor involved in vascular remodeling and angiogenesis. As evidenced by RT-PCR, the S/L ratio of endoglin isoforms was increased during senescence of human ECs in vitro, as well as during aging of mice in vascularized tissues. Next, the effect of S-endoglin protein on the TGF-beta receptor complex was studied. As revealed by coimmunoprecipitation assays, S-endoglin was able to interact with both TGF-beta type I receptors, ALK5 and ALK1, although the interaction with ALK5 was stronger than with ALK1. S-endoglin conferred a lower proliferation rate to ECs and behaved differently from L-endoglin in relation to TGF-beta-responsive reporters with ALK1 or ALK5 specificities, mimicking the behavior of the endothelial senescence markers Id1 and plasminogen activator inhibitor-1. In situ hybridization studies demonstrated the expression of S-endoglin in the endothelium from human arteries. Transgenic mice overexpressing S-endoglin in ECs showed hypertension, decreased hypertensive response to NO inhibition, decreased vasodilatory response to TGF-beta(1) administration, and decreased endothelial nitric oxide synthase expression in lungs and kidneys, supporting the involvement of S-endoglin in the NO-dependent vascular homeostasis. Taken together, these results suggest that S-endoglin is induced during endothelial senescence and may contribute to age-dependent vascular pathology.
内皮细胞（ECs）衰老可能导致与年龄相关的心血管疾病，包括动脉粥样硬化和高血压。与细胞衰老相关的功能和基因表达变化目前了解甚少。在此，我们分析了内皮糖蛋白（一种参与血管重塑和血管生成的辅助转化生长因子（TGF）-β受体）的两种不同异构体（L，长；S，短）在EC衰老过程中的表达情况。逆转录聚合酶链反应（RT-PCR）结果表明，体外培养的人EC衰老过程中以及血管化组织中衰老小鼠体内，内皮糖蛋白异构体的S/L比值均升高。接下来，研究了S-内皮糖蛋白对TGF-β受体复合物的影响。免疫共沉淀分析显示，S-内皮糖蛋白能够与TGF-β I型受体ALK5和ALK1相互作用，尽管与ALK5的相互作用强于与ALK1的相互作用。S-内皮糖蛋白使EC的增殖速率降低，并且在具有ALK1或ALK5特异性的TGF-β反应性报告基因方面，其表现与L-内皮糖蛋白不同，类似于内皮衰老标志物Id1和纤溶酶原激活物抑制剂-1的行为。原位杂交研究表明，人动脉内皮中存在S-内皮糖蛋白的表达。在EC中过表达S-内皮糖蛋白的转基因小鼠表现出高血压、对NO抑制的高血压反应降低、对TGF-β(1)给药的血管舒张反应降低以及肺和肾中内皮型一氧化氮合酶表达降低，这支持了S-内皮糖蛋白参与依赖NO的血管稳态。综上所述，这些结果表明，S-内皮糖蛋白在内皮衰老过程中被诱导，可能导致年龄依赖性血管病变。
