Role of Glutathione S-Transferase P in Heart Failure

描述（由申请人提供）：虽然氧化应激是心力衰竭（HF）的标志，但针对第一代活性氧（ROS）（如O2/和H2O2）的抗氧化剂的临床试验尚未产生令人信服的益处。然而，ROS也会产生源自脂质过氧化的二级中间体，包括过氧化物和醛，它们会放大氧化损伤。谷胱甘肽s -转移酶（GSTs）通过催化醛与谷胱甘肽（GSH）的结合来代谢醛。某些GST亚型也具有重要的非催化功能，如与c-Jun n-末端激酶（JNK）的物理相互作用，这些相互作用由氧化应激调节。虽然GSTs在氧化应激反应中起着至关重要的作用，但GSTs如何影响HF尚不清楚。我们的目标是确定GSTP（最丰富的心脏GST异构体）在心衰中的功能作用。我们的初步研究表明，GSTP在HF中下调，GSTP缺乏会加重心脏重构，增加蛋白-醛加合物，抑制循环内皮祖细胞（EPCs），并损害新生血管。因此，我们的中心假设是GSTP在梗死后HF中是一种关键的心脏保护蛋白，可以改善重构并促进心脏修复。为了验证这一假设，我们将执行三个具体目标。在Aim 1中，我们将通过检测野生型（WT）、GSTP-/-和心脏特异性hGSTP1*A和hGSTP1*C转基因（Tg）小鼠梗死后左室重构，确定GSTP和人类GSTP变体hGSTP1*A和hGSTP1*C在HF中的作用。我们将评估凋亡、纤维化和炎症以及谷胱甘肽水平、蛋白内合醛和JNK在心脏中的激活。在Aim 2中，我们将确定GSTP对衰竭心脏中脂质过氧化产物解毒的代谢贡献。在WT、GSTP-/-和hGSTP Tg小鼠的离体、灌注假手术和衰竭心脏中，我们将使用同位素标记和质谱技术来表征不饱和醛的代谢和解毒作用。在组织匀浆中，我们还将测定与gstp相关的过氧化物酶活性以及醛类和脂质过氧化物的水平。在Aim 3中，我们将描述GTSP调节衰竭心脏新生血管的心脏和骨髓（BM）相关效应。我们将首先在WT和GSTP -/-小鼠中测定EPC和BM祖细胞的功能，无论是否伴有JNK抑制。接下来，我们将定义GSTP消融和hGSTP过表达如何影响假手术心脏和衰竭心脏的新生血管和血管生成基因表达。最后，我们将评估嵌合小鼠的梗死后重塑、炎症、EPC动员和新生血管：GSTP-/- BM的WT小鼠和GSTP-/- BM的WT小鼠。这些研究将确定心肌定位与脑定位GSTP在衰竭心脏重构、新生血管和炎症过程中的作用。总的来说，这项工作将建立一个新的范例，即GSTP是心衰中必不可少的抗氧化、抗炎和促血管生成蛋白。该模型对心衰患者氧化损伤的诊断和治疗具有重要意义。

DESCRIPTION (provided by applicant): Although oxidative stress is a hallmark of heart failure (HF), clinical trials with antioxidants targeting first generation reactive oxygen species (ROS) such as O2/ and H2O2 have not yielded compelling benefits. However, ROS also generate secondary intermediates derived from lipid peroxidation, including peroxides and aldehydes that amplify oxidative injury. Glutathione S-transferases (GSTs) metabolize aldehydes by catalyzing their conjugation with glutathione (GSH). Select GST isoforms also have important non-catalytic functions such as physical interactions with c-Jun N-terminal kinase (JNK) that are modulated by oxidative stress. Although GSTs play a vital role in oxidative stress responses, how GSTs impact HF is unknown. Our goal is to define the functional role of GSTP, most abundant cardiac GST isoform, in HF. Our preliminary studies indicate that GSTP is downregulated in HF, and that GSTP deficiency worsens cardiac remodeling, augments protein- aldehyde adducts, depresses circulating endothelial progenitor cells (EPCs), and impairs neovascularization. Our central hypothesis, therefore, is that GSTP is a critical cardioprotective protein in post-infarction HF that ameliorates remodeling and promotes cardiac repair. To test this hypothesis, we will perform three Specific Aims. In Aim 1, we will define the role of GSTP, and the human GSTP variants hGSTP1*A and hGSTP1*C, in HF by examining post-infarction LV remodeling in wild-type (WT), GSTP-/-, and cardiac-specific hGSTP1*A and hGSTP1*C transgenic (Tg) mice. We will evaluate apoptosis, fibrosis, and inflammation together with glutathione levels, protein-adducted aldehydes, and JNK activation in the heart. In Aim 2, we will determine the metabolic contribution of GSTP to the detoxification of lipid peroxidation products in the failing heart. In isolated, perfused sham-operated and failing hearts from WT, GSTP-/- and hGSTP Tg mice, using isotope labeling and mass spectrometry, we will characterize the metabolism and detoxification of unsaturated aldehydes. In tissue homogenates, we will also determine GSTP-related peroxidase activity and levels of aldehydes and lipid peroxides. In Aim 3, we will delineate the cardiac and bone marrow (BM)-related effects by which GTSP modulates neovascularization in the failing heart. We will first determine EPC and BM progenitor cell function in WT and GSTP -/- mice, both with and without concomitant JNK inhibition. Next, we will define how GSTP ablation and hGSTP overexpression affect neovascularization and angiogenic gene expression in the sham and failing hearts from Aim 1. Lastly, we will evaluate post-infarction remodeling, inflammation, EPC mobilization, and neovascularization in chimeric mice: WT mice with GSTP-/- BM and GSTP-/- mice with WT BM. These studies will establish the role of myocardium-localized versus BM-localized GSTP in the process of remodeling, neovascularization, and inflammation in the failing heart. Collectively, this work will establish a novel paradigm of GSTP as an essential antioxidant, anti-inflammatory, and pro-angiogenic protein in HF. This model can have important diagnostic and therapeutic implications for HF patients with regard to oxidant injury. PUBLIC HEALTH RELEVANCE: These studies will establish glutathione S-transferase P (GSTP) as a critical antioxidant and tissue reparative protein in heart failure and identify new determinants of oxidative injury. Hence, the results can help design new, non-classical antioxidant and regenerative therapies in heart failure. We will also evaluate the cardioprotective potency of human GSTP variants in the failing heart; important differences between GSTP variants can establish a genetic basis for variability of antioxidant responses in the heart and provide a novel biomarker for the progression of heart failure.