BMP Signaling and Pulmonary Vasoreactivity

BMP 信号传导和肺血管反应性

• 批准号: 8120666
• 负责人: Mark P. de Caestecker
• 金额: $ 39万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-05 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8120666
• 关键词: Age; Agonist; BMPR2 gene; Binding; Blood Vessels; Cell Culture Techniques; Cell membrane; Cell surface; Chemicals; Chronic; Communities; Complex; Defect; Deletion Mutation; Development; Diagnosis; Disease; Endoplasmic Reticulum; Endothelial Cells; Exons; Foundations; Functional disorder; Genetic Models; Golgi Apparatus; Hypoxia; Inherited; Ligands; Lung; MAP Kinase Gene; MAPK14 gene; Mediating; Mediator of activation protein; Messenger RNA; Minor; Modeling; Molecular; Molecular Chaperones; Mus; Mutant Strains Mice; Mutation; Pathway interactions; Patients; Phenotype; Phosphorylation; Play; Process; Proteins; Proto-Oncogene Proteins c-akt; Pulmonary Hypertension; Regulation; Relative (related person); Role; Serotonin; Severities; Signal Pathway; Signal Transduction; Small Interfering RNA; Testing; Therapeutic; Transgenic Mice; Vascular Diseases; Vascular remodeling; bone morphogenetic protein receptor type II; insight; mRNA Decay; mutant; pressure; prevent; public health relevance; pulmonary arterial hypertension; receptor; response; trafficking

DESCRIPTION (provided by applicant): Patients with Familial Pulmonary Hypertension (FPAH) inherit heterozygous mutations in the BMP type 2 receptor BMPR2. It is unknown how these mutations cause pulmonary hypertension (PH). Half of these mutations escape Nonsense Mediated mRNA Decay and express BMPR2 mutant mRNA (NMD negative). Others are NMD positive and do not express mutant products. As NMD negative mutations express mutant gene products they may exert dominant inhibitory effects on the pulmonary vasculature. Recent evidence supports this: the age at diagnosis is younger in FPAH patients with NMD negative versus NMD positive BMPR2 mutations. This suggests NMD negative mutations cause more severe disease. Preliminary studies in mice carrying different Bmpr2 mutations suggest a mechanism by which this occurs. Mice with the heterozygous Bmpr2 Exon 2 deletion mutation (Bmpr2?Ex2/+) have more severe PH than mice carrying heterozygous null Bmpr2+/- mutations. This is associated with reduced eNOS activity and endothelial cell dysfunction in Bmpr2?Ex2/+ pulmonary vasculature. Over-expression of eNOS reverses the PH phenotype in Bmpr2?Ex2/+ mutant mice, indicating that eNOS deficiency plays a critical role in exacerbating PH. Furthermore, there is abnormal intracellular processing of the Bmpr2?Ex2 mutant product, and this interferes with eNOS function by abnormal intracellular sequestration of eNOS. As similar NMD negative Exon 2 deletion mutants are found in FPAH patients, these findings suggest that eNOS deficiency may be a common mechanism by which NMD negative BMPR2 mutations exacerbate PH in patients with FPAH. Three aims are proposed to test this hypothesis and define the mechanism by which this occurs. Aim 1 will compare vasoreactivity, PH responses and eNOS activity in the pulmonary vasculature of Bmpr2?Ex2/+ and Bmpr2+/- mice. Aims 2 will use cell culture techniques to evaluate how BMP signaling normally regulates eNOS expression and activity in pulmonary endothelial cells, while Aim 3 will compare eNOS regulation in Bmpr2+/- and Bmpr2?Ex2/+ mice, and will determine the molecular mechanism by which the Bmpr2?Ex2/+ mutant product exerts dominant inhibitory effects on eNOS activity in pulmonary endothelial cells. These studies will provide insight into how NMD positive FPAH BMPR2 mutations (like the Bmpr2+/- mutation) vs. NMD negative mutations (which are expressed and may behave like the Bmpr2?Ex2/+ mutation) modify vascular responses in patients with FPAH. By defining the mechanism by which Bmpr2?Ex2 inhibits eNOS they will also establish the foundation for therapeutic approaches to ameliorate PH by correcting NMD negative BMPR2 mutant processing defects in FPAH. PUBLIC HEALTH RELEVANCE: Pulmonary Arterial Hypertension is an invariably fatal disease for which there is no curative treatment. A major challenge for the scientific community therefore is to develop therapeutic approaches to prevent the progression of pulmonary vascular disease that develops in these patients. Our studies will provide important insight into a common pathway that regulates this process and identify approaches to interfere with this pathway and prevent the development of irreversible pulmonary vascular disease in these patients.

描述（由申请人提供）：家族性肺动脉高压（FPAH）患者遗传了 BMP 2 型受体 BMPR2 的杂合突变。目前尚不清楚这些突变如何导致肺动脉高压（PH）。这些突变中有一半逃脱了无义介导的 mRNA 衰变并表达 BMPR2 突变体 mRNA（NMD 阴性）。其他为 NMD 阳性且不表达突变产物。由于 NMD 阴性突变表达突变基因产物，它们可能对肺血管系统产生显着的抑制作用。最近的证据支持这一点：与 NMD 阳性 BMPR2 突变的 NMD 阴性 FPAH 患者相比，诊断时的年龄更年轻。这表明 NMD 阴性突变会导致更严重的疾病。对携带不同 Bmpr2 突变的小鼠进行的初步研究表明了这种情况发生的机制。具有杂合 Bmpr2 外显子 2 缺失突变 (Bmpr2?Ex2/+) 的小鼠比携带杂合无效 Bmpr2+/- 突变的小鼠具有更严重的 PH。这与 Bmpr2?Ex2/+ 肺血管系统中 eNOS 活性降低和内皮细胞功能障碍有关。 eNOS 的过度表达逆转了 Bmpr2?Ex2/+ 突变小鼠的 PH 表型，表明 eNOS 缺乏在加剧 PH 中起着关键作用。此外，Bmpr2?Ex2突变产物的细胞内加工异常，并且这通过eNOS的异常细胞内隔离来干扰eNOS功能。由于在 FPAH 患者中发现了类似的 NMD 阴性外显子 2 缺失突变体，这些发现表明 eNOS 缺陷可能是 NMD 阴性 BMPR2 突变加剧 FPAH 患者 PH 的常见机制。提出了三个目标来检验这一假设并定义其发生的机制。目标 1 将比较 Bmpr2?Ex2/+ 和 Bmpr2+/- 小鼠肺血管系统中的血管反应性、PH 反应和 eNOS 活性。目标 2 将使用细胞培养技术评估 BMP 信号传导如何正常调节肺内皮细胞中的 eNOS 表达和活性，而目标 3 将比较 Bmpr2+/- 和 Bmpr2?Ex2/+ 小鼠中的 eNOS 调节，并确定其分子机制Bmpr2?Ex2/+ 突变体产物对肺内皮细胞中的 eNOS 活性发挥显着的抑制作用。这些研究将深入了解 NMD 阳性 FPAH BMPR2 突变（如 Bmpr2+/- 突变）与 NMD 阴性突变（其表达和行为可能类似于 Bmpr2?Ex2/+ 突变）如何改变 FPAH 患者的血管反应。通过定义 Bmpr2?Ex2 抑制 eNOS 的机制，他们还将通过纠正 FPAH 中 NMD 阴性 BMPR2 突变体加工缺陷来改善 PH 的治疗方法奠定基础。 公共卫生相关性：肺动脉高压是一种无法治愈的致命疾病。因此，科学界面临的一个主要挑战是开发治疗方法来预防这些患者发生的肺血管疾病的进展。我们的研究将为调节这一过程的共同途径提供重要的见解，并确定干扰该途径并防止这些患者发生不可逆肺血管疾病的方法。