Interventions Against the Molecular Etiology of BMPR2-induced PAH

描述（由申请人提供）：本项目的总体目的是在分子水平上确定BMPR2的抑制或突变如何导致肺动脉高压（PAH），以便确定干预点。如下文进度报告所述，这在头三年取得了巨大成功。目前的更新重点是发展我们的发现在能量代谢向谷氨酰胺解的转变。谷氨酰胺是一种非必需氨基酸，在一些癌症中，根据我们的数据，在多环芳烃中，它已经成为主要的线粒体底物。这种增加的谷氨酰胺摄取是BMPR2突变体和癌症细胞存活和生长所必需的，但在健康组织中不需要，使其成为一个很好的诊断和治疗靶点。我们首先在BMPR2突变小鼠的基因表达研究中发现了谷氨酰胺水解的转变。通过谷氨酰胺摄取研究、使用标记谷氨酰胺的稳定同位素示踪研究以及通过生长曲线证明对过量谷氨酰胺的需求，Bmpr2突变细胞对谷氨酰胺的依赖性增加得到了独立证实。临床研究表明，在任何病因的PAH患者中，血清谷氨酰胺水平增加了两倍，同时PAH患者肺部谷氨酰胺水平下降了50%。这种对谷氨酰胺依赖的转变以前只在肿瘤过程中看到过。氧化应激和代谢缺陷很可能是疾病的基础，而不是旁观者。我们已经在三种分子不同的小鼠模型中表明，这些代谢变化是发病机制的一部分，现在有两例患者的病例报告，这些变化的逆转导致了戏剧性的血流动力学改善。拟议的研究将确定谷氨酰胺解的转变是如何发生的，干扰它是否可能在临床上有用，以及它是否可以用作患者的诊断工具。

DESCRIPTION (provided by applicant): The overall purpose of this project is to determine on a molecular level how suppression or mutation of BMPR2 results in pulmonary arterial hypertension (PAH), in order to identify points for intervention. This has been a tremendous success in the first three years, as described in the progress report following. The current renewal focuses on developing our findings on a shift in energy metabolism towards glutaminolysis. Glutamine is a nonessential amino acid which in some cancers, and in PAH according to our data, has become the primary mitochondrial substrate. This increased glutamine uptake is required for cell survival and growth in BMPR2 mutants and cancer, but not in healthy tissue, making it an excellent diagnostic and therapeutic target. We first identified th shift to glutaminolysis in gene expression studies of BMPR2 mutant mice. The increased reliance on glutamine in Bmpr2 mutant cells was confirmed independently through glutamine uptake studies, stable isotope tracer studies using labeled glutamine, and through growth curves demonstrating a requirement for excess glutamine. Clinical studies demonstrated a twofold increase in serum glutamine levels in PAH patients of any etiology, combined with a 50% drop in glutamine levels across the lungs in PAH patients. This shift to reliance on glutamine has previously only been seen in neoplastic processes. The oxidative stress and metabolic defects are likely to be the basis of disease, not bystanders. We have shown in three molecularly different mouse models that these metabolic changes are part of pathogenesis, and there are now case reports on two patients in whom reversal of these changes resulted in dramatic hemodynamic improvement. The proposed studies will determine how the shift to glutaminolysis is happening, whether interfering with it is likely to be clinically useful, and whether it can be used as a diagnostic tool in patients.