Mitochondrial Fission, Calcium, ROS in Right Ventricular Fibrosis

右心室纤维化中的线粒体裂变、钙、ROS

基本信息

批准号：
10734675
负责人：
Bong Sook Jhun
金额：
$ 38.75万
依托单位：
UNIVERSITY OF MINNESOTA
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-07-01 至 2027-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10734675
关键词：
Antioxidants Apoptosis Apoptotic Attenuated Bax protein Calcium Cardiac Cardiac Myocytes Cause of Death Cell Membrane Permeability Cell Nucleus Chronic Clinical Collagen Cyclic AMP-Dependent Protein Kinases Data Development Dominant-Negative Mutation Dynamin Enzymes Extracellular Matrix Failure Fibroblasts Fibrosis Functional disorder Goals Injury Left Link Mediating Mitochondria Mitochondrial Proteins Modeling Molecular Myofibroblast Names Nuclear Nuclear Proteins Outcome Outer Mitochondrial Membrane Pathologic Patients Phenotype Phosphorylation Physiologic intraventricular pressure Process Prognosis Proliferating Protein Inhibition Proteins Pulmonary Hypertension Rattus Reactive Oxygen Species Reporting Research Resistance Right Ventricular Function Right Ventricular Hypertrophy Role Signal Transduction Stress Testing Ventricular conventional therapy coronary fibrosis design improved in vivo interstitial mitochondrial permeability transition pore mortality novel novel strategies novel therapeutic intervention novel therapeutics pre-clinical pressure pro-apoptotic protein protein kinase D pulmonary arterial hypertension response response to injury right ventricular failure therapeutic evaluation uptake

项目摘要

Project Summary: Growing evidence suggests the link between right ventricular (RV) fibrosis, poor function of the pressure-overloaded RV, and mortality in pulmonary arterial hypertension (PAH). PAH patients with decompensated RV failure (RVF) have persistent RV fibrosis even when treated with the conventional therapies for PAH. RVF is the main cause of death in PAH and maintaining RV function in PAH is associated with improved patient survival. However, there are currently no available therapies that specifically target RV fibrosis. Therefore, identifying the molecular mechanisms underlying RV fibrosis in PAH is urgently needed to develop novel therapeutic approaches targeting RVF in PAH. We recently reported the significant roles of o xidative stress-sensitive protein kinase D (PKD) at outer mitochondrial membrane (OMM) and its substrate dynamin-related protein 1 (DRP1), a mitochondrial fission protein, in dysregulating CM functions. We also showed that DRP1-mediated mitochondrial fission limits the size of the matrix cavity, thus causing elevated and sustained mitochondrial Ca2+ (mtCa2+) transient in response to cytosolic Ca2+ elevation. Using a preclinical rat PAH model with RV hypertrophy, failure, and fibrosis that significant , we found PKD activation and DRP1 phosphorylation occurs specifically in cardiac fibroblasts (CFs) in the RV (RV-CFs), but not in CMs under PAH, which subsequently causes an PKD-dependent increase in mitochondrial fission, mitochondrial reactive oxygen species (mROS), and CF proliferation. Moreover, we found that PKD activation is associated with increased phosphorylation of a pro-apoptotic protein Bax, which inhibits apoptotic pore formation in the OMM and potentially contributes to the anti-apoptotic phenotype of RV-CFs in PAH. Lastly, we also found that mtCa2+ uptake via mtCa2+ uniporter (MCU) is required for mROS elevation and subsequent activation of proliferative signaling in CFs. Based on these findings, we hypothesize that 1) PKD-dependent Bax phosphorylation allows RV-CFs to be resistant to apoptosis under PAH; 2) PKD-dependent mitochondrial fission limits mtCa2+ and antioxidant capacity by decreasing the size of the matrix cavity and causing increased mtCa2+ and mROS levels, thus acting as a molecular “switch” for proliferative signaling for RV-CFs in PAH; and 3) CF-specific inhibition of PKD at the OMM in vivo can be leveraged as a novel therapy to attenuate cardiac fibrosis in response to stress/injury such as PAH. In Aim 1, we will establish Bax as a novel PKD substrate in the mitochondria and assess the impact of PKD-dependent Bax phosphorylation on OMM permeability. To specifically inhibit PKD activity only at the OMM, we will use an OMM-targeted dominant-negative PKD1 (mt-PKD- DN) that we have newly validated. In Aim 2, we will test whether PKD-dependent enhancement of mitochondrial fission facilitates RV-CF proliferation via increased mtCa2+ and mROS levels. In Aim 3, we will test the therapeutic potential of mitochondrial PKD inhibition by mt-PKD-DN in the quiescent CFs before they transform into myofibroblasts by CF- specifically expressing mt-PKD-DN in a preclinical rat PAH model. The proposed project is designed to determine the role of mitochondrial fission, Ca2+, and mROS in RV-CF hyperproliferation and RV fibrosis in PAH, which will lead to develop a novel strategy (i.e., PKD inhibition) for the management of RV fibrosis and failure in the setting of PAH.

项目概要：越来越多的证据表明右心室（RV）纤维化与压力超载功能不良之间存在联系右心室失代偿衰竭 (RVF) 的肺动脉高压 (PAH) 患者的 RV 和死亡率。即使采用传统的 RVF 治疗方法，持续性 RV 纤维化仍是导致 RVF 死亡的主要原因。 PAH 和维持 PAH 中的 RV 功能与改善患者生存率相关，但目前尚无相关证据。因此，确定 RV 潜在的分子机制。迫切需要开发针对 PAH RVF 的新治疗方法。我们最近报道了 o 的重要作用氧化应激敏感蛋白激酶 D (PKD) 位于外侧线粒体膜 (OMM) 及其底物动力相关蛋白 1 (DRP1)（一种线粒体裂变蛋白）我们还发现 DRP1 介导的线粒体裂变限制了基质的大小。腔，从而导致并持续线粒体 Ca2+ (mtCa2+) 瞬时响应胞质 Ca2+ 升高。使用具有 RV 肥大、衰竭和纤维化的临床前大鼠 PAH 模型，显着，我们发现公钥簿激活 DRP1 磷酸化特异发生存在于右心室 (RV-CF) 中的心脏成纤维细胞 (CF) 中，但不存在于 CM 中 PAH，随后导致线粒体裂变、线粒体活性氧的 PKD 依赖性增加此外，我们发现 PKD 激活与增加有关。促凋亡蛋白 Bax 的磷酸化，可抑制 OMM 中凋亡孔的形成，并可能最后，我们还发现 mtCa2+ 通过 mtCa2+ 摄取，从而有助于 RV-CF 的抗凋亡表型。 mROS 升高和随后 CF 中增殖信号的激活需要单向转运蛋白 (MCU)。这些发现，我们追求1）PKD依赖性Bax磷酸化使得RV-CF能够抵抗细胞凋亡 PAH 下；2) PKD 依赖性线粒体裂变通过减小 mtCa2+ 的大小来限制 mtCa2+ 和抗氧化能力基质空腔并导致 mtCa2+ 和 mROS 水平增加，从而充当增殖的分子“开关” PAH 中 RV-CF 的信号传导；3）体内 OMM 处的 CF 特异性抑制可作为一种新型药物减轻心脏纤维化以应对压力/损伤（如 PAH）的疗法在目标 1 中，我们将 Bax 确立为一种新型疗法。线粒体中的 PKD 底物并评估 PKD 依赖性 Bax 磷酸化对 OMM 通透性的影响。为了仅在 OMM 处特异性抑制 PKD 活性，我们将使用 OMM 靶向显性失活 PKD1 (mt-PKD- DN），我们新近验证了这一点。在目标 2 中，我们将测试线粒体裂变是否依赖于 PKD 增强。通过增加 mtCa2+ 和 mROS 水平促进 RV-CF 增殖在目标 3 中，我们将测试其治疗潜力。在静态 CF 转化为肌成纤维细胞之前，mt-PKD-DN 抑制线粒体 PKD 在临床前大鼠 PAH 模型中特异性表达 mt-PKD-DN。拟议项目旨在确定线粒体裂变、Ca2+和 mROS 在 PAH 中 RV-CF 过度增殖和 RV 纤维化中的作用，这将导致开发一种新策略（即 PKD 抑制）来管理 PAH 情况下的 RV 纤维化和衰竭。