Ectonucleotidase modulation of age-dependent vascular calcification and stiffness

摘要 随着年龄的增长，血管变得更加僵硬和钙化。在人类生命的最后几年， 血管老化的过程加速。血管失去年轻时的弹性， 人们对延缓钙在生命后期急剧沉积的能力知之甚少。外核苷酸酶是 发现于内皮细胞表面，内皮细胞排列在血管、血管平滑肌 细胞和白细胞。外核苷酸酶CD 39负责切割ATP和ADP以形成AMP， 随后，CD 73负责从AMP产生腺苷。由于ATP和ADP是亲- 炎性并以旁分泌方式起作用，我假设外核苷酸酶活性在 血管硬化和钙化是年龄的结果。这一点得到了我初步的支持。 野生型（C57 BL/6）小鼠的数据，表明CD 73蛋白水平随年龄（最多24个月）而下降 心脏和肾脏这也得到了小鼠和人体组织初步数据的支持， CD 73表达的缺失促进了转录因子Runx 2的表达，这对于 成骨我们假设随着年龄的增长外核苷酸酶表达的丧失可能会对 对血管壁的影响，导致促进血管钙化的环境， 刚度由于外核苷酸酶在血管老化中的作用尚不清楚，我们将阐明其机制 其通过以下目的介导年龄依赖性血管钙化。目标1：我们将确定如何 血管外核苷酸酶表达的年龄依赖性下降使血管对血管内皮细胞增殖敏感， 钙化和纤维化。目标2：我们将确定外核苷酸酶活性如何减轻 动脉纤维化和僵硬。目的3：我们将确定外核苷酸酶的表达是否在年龄驱动的 人体冠状动脉钙化这些目标的实现将阐明外核苷酸酶的作用， 年龄依赖性血管钙化和僵硬的小鼠和人类。获得的机械见解 这些实验将确定我未来的研究方向，并作为后续研究的基础 RO 1申请作为研究血管生物学和衰老的独立研究者。

Abstract With increasing age, blood vessels become stiffer and more calcified. In the latter years of the human lifespan, the process of vascular aging accelerates. The reason that blood vessels lose their youthful elasticity and ability to retard the deposition of calcium precipitously later in life is poorly understood. Ectonucleotidases are found on the surface of endothelial cells which line the inner surface of blood vessels, vascular smooth muscle cells, and leukocytes. The ectonucleotidase CD39 is responsible for cleaving ATP and ADP to form AMP, and subsequently, CD73 is responsible for generating adenosine from AMP. Since ATP and ADP are pro- inflammatory and act in a paracrine fashion, I hypothesize that ectonucleotidase activity plays a role in the vascular stiffness and calcification that occurs as a consequence of age. This is supported by my preliminary data in wild type (C57BL/6) mice, which demonstrates CD73 protein levels declined with age (up to 24 months) in the heart and kidney. This is also supported by preliminary data in mice and human tissues demonstrating that loss of CD73 expression promoted expression of the transcription factor Runx2, which is critical for osteogenesis. We hypothesize that loss of ectonucleotidase expression with age could have deleterious consequences on the vessel wall, resulting in an environment which promotes vascular calcification and stiffness. Since the role of ectonucleotidases in vascular aging is unknown, we will elucidate mechanisms which mediate age-dependent vascular calcification through the following aims. Aim 1: We will determine how age-dependent decline in vascular ectonucleotidase expression renders vessels susceptible to vascular calcification and fibrosis in a murine model. Aim 2: We will determine how ectonucleotidase activity mitigates arterial fibrosis and stiffness. Aim 3: We will determine if ectonucleotidase expression plays a role in age-driven human coronary artery calcification. Achievement of these aims will elucidate the role of ectonucleotidases in age-dependent vascular calcification and stiffness in mice and humans. The mechanistic insights obtained from these experiments will define my future investigative direction and serve as a foundation for a subsequent RO1 application as an independent investigator studying vascular biology and aging.