Regulation of Purine Metabolism by Protein Methyltransferase Smyd1

项目摘要 慢性心力衰竭的病理生理学认识已从单纯的血液动力学紊乱转变为 一种更为复杂的综合征，包括神经激素、免疫、转录等方面的变化和失衡 和新陈代谢功能。在代谢异常中，慢性心力衰竭与 尿酸(高尿酸血症)水平升高，尿酸是嘌呤代谢的最终产物。具体地说，研究表明 显示血清尿酸水平与心血管发病率和死亡率之间有很强的相关性，尤其是 心血管风险高的个人，包括高血压、糖尿病和充血性心脏病患者 失败了。嘌呤代谢异常也是众所周知的，它通过黄嘌呤作用于ROS的产生。 氧化酶，这一途径中的最后一种酶，越来越被认为是两者的重要贡献者 慢性心力衰竭的症状以及疾病的进展。事实上，治疗性抑制 心力衰竭患者体内黄嘌呤氧化酶活性的增加(通过别嘌醇)已被证明可以抵消 不适应的慢性嘌呤代谢上调与外周血流的特殊益处 并减少自由基的产生，这表明通过治疗来靶向这一途径可以 对心力衰竭患者有益。然而，驱动这些嘌呤变化的潜在机制 心力衰竭患者心肌细胞的代谢和最终的ROS和尿酸积聚 很大程度上是未知的。 我们最近发现了甲基转移酶Smyd1b，它在胞质和胞浆中都发挥着独特的作用 细胞核与代谢酶ADSS(腺苷琥珀酸合成酶)相互作用，ADSS是嘌呤的关键成分 心脏的新陈代谢。我们已经证实Smyd1b和ADS之间的这种新的相互作用在 苯肾上腺素诱导心肌细胞肥大并与甲基化增加有关 美国存托凭证。此外，我们还发现，Smyd1在将imp转化为 Samp的体外实验。尽管有这些耐人寻味的结果，Smyd1如何调节ADS活性及其对嘌呤的影响 新陈代谢和尿酸的产生完全未知。我的奖学金申请将使用一种独特的基因 动物模型和最新的蛋白质组学技术从概念上促进我们对心肌细胞的理解 生物学和生理学。具体地说，这项工作将确定Smyd1在调节ADS活性中的作用。 成人心脏，表征其影响ROS产生和尿酸积累的能力，并确定 Smyd1的过表达是否能抑制这些有害过程。共同努力，我的实验将建立 并允许我解释一下Smyd1b的具体分子机制 调节心脏中的嘌呤代谢，以及在正常和肥厚的情况下这个过程是如何调节的 条件。

PROJECT ABSTRACT The pathophysiological understanding of chronic heart failure has shifted from a mere hemodynamic disorder to a much more complex syndrome including changes and imbalances in neurohormonal, immune, transcriptional and metabolic functions. Among the metabolic abnormalities, chronic heart failure has been associated with increased levels of uric acid (hyperuricemia), the end product of purine metabolism. Specifically, studies have shown a strong association between serum uric acid levels and cardiovascular morbidity and mortality, especially among individuals with high cardiovascular risk, including those with hypertension, diabetes and congestive heart failure. Abnormal purine metabolism is also known for its contribution to ROS production through xanthine oxidase, the final enzyme in this pathway, which is increasingly appreciated as an important contributor to both symptoms of chronic heart failure as well as progression of the disease. Indeed, therapeutic inhibition of increased xanthine oxidase activity (via allopurinol) in heart failure patients has been shown to counteract maladaptive chronic upregulation of purine metabolism with specific benefits observed in peripheral blood flow and decreased free oxygen radical generation, suggesting that targeting this pathway therapeutically can be beneficial for heart failure patients. However, the underlying mechanisms which drive these changes in purine metabolism in the cardiomyocyte and ultimately ROS and uric acid accumulation in heart failure patients remain largely unknown. We recently discovered that the methyltransferase Smyd1b, which displays unique roles in both the cytosol and nucleus, interacts with the metabolic enzyme Adss (Adenylossuccinate Synthatase), a key component of purine metabolism in the heart. We have confirmed this novel interaction between Smyd1b and Adss is enhanced during phenylephrine-induced hypertrophic growth in the cardiomyocyte and is associated with increased methylation of Adss. In addition, we have shown that Smyd1 enhances the enzymatic activity of Adss as it converts IMP to sAMP in vitro. Despite these intriguing results, how Smyd1 regulates Adss activity and its effect on purine metabolism and uric acid production is completely unknown. My fellowship application will utilize a unique genetic animal model and state-of-the-art proteomic technologies to conceptually advance our understanding of myocyte biology and physiology. Specifically, this work will determine the role of Smyd1 in regulating Adss activity in the adult heart, characterize its ability to influence ROS production and uric acid accumulation, and determine whether overexpression of Smyd1 can inhibit these deleterious processes. Together, my experiments will build upon our previous results and allow me to elucidate the specific molecular mechanism by which Smyd1b regulates purine metabolism in the heart and how this process is regulated under normal and hypertrophic conditions.