Gender Effects on Remodeling of Lipid and Sarcomere Dynamics in Hypertrophy

描述（由申请人提供）：性别影响心力衰竭的发病机制，尽管在肌细胞收缩力上没有固有的差异。在病理生理应激过程中，人类和动物的脂质动态表现出性别差异。然而，性别在心脏失代偿发病机制中的作用，作为改变心脏脂质的决定因素，在很大程度上是未知的。本研究的重点是性别、饮食脂肪和压力过载引起的应激所引起的机制，这些机制改变了线粒体氧化和长链脂肪酸（LCFA）细胞储存之间的平衡，从而影响肌丝的生物化学和活性。我们将研究性别和雌激素对压力过载时心脏脂质动力学重塑的影响，重点关注心脏功能的主动和被动成分；主动成分是由于代谢信号引起的肌合成蛋白内的生化变化，被动成分是由于脂质浸润引起的心肌僵硬。初步数据表明，脂质积累导致心肌僵硬，性别影响心脏脂质动力学和酰基衍生物。我们报道了肥大心脏中三酰基甘油酯（TAG）周转减少和TAG对线粒体氧化的贡献，并发现酰基衍生物影响肌丝磷酸化和对Ca2+的敏感性。我们计划将心脏功能和脂质含量的体内测量与代谢通量的稳定同位素动力学和肌丝蛋白质组学相结合，以解决一个双重假设：1)由于雌激素的性别差异，影响心脏肥厚的代谢重编程，脂质利用/储存的改变影响心脏功能；2)膳食脂肪的储存（PPAR¿过表达）和摄取（FATP1过表达）揭示了心脏脂质动力学的性别特异性变化，影响心肌依从性和肌节活性。目的是：1)研究雄性、雌性和过度切除雌性、非转基因（NTG）和MHC-PPAR¿低过表达（品系404-4）小鼠心脏中脂质利用/储存动态的性别和雌激素依赖性差异；2)测试LCFA摄取、性别和雌激素对压力过载反应的影响，通过测定a)脂质动力学及其对心肌2- d株、组织刚度和收缩性的影响；b)神经酰胺种类和鞘氨醇产生及其对非转基因小鼠和过表达FATP1的转基因小鼠心脏肌丝磷酸化、氧化和钙反应的影响；3)确定压力过载时TAG动力学和LCFA氧化率的性别适应潜力，通过脂质积累的机械效应影响a)心肌2-D应变和刚度，以及b) LCFA衍生中间体、神经酰胺和鞘氨醇的磷酸化作用影响MHC-PPAR心脏肌丝敏感性的肌节活性。目的是阐明影响心功能的心脏脂质动力学重编程机制，从而确定早期诊断策略和性别特异性治疗方案，以减轻心肌病的发展。

DESCRIPTION (provided by applicant): Gender influences the pathogenesis of heart failure, despite no inherent differences in myocyte contractility. Both humans and animals show gender differences in lipid dynamics during pathophysiological stress. Yet, the role of gender, as a determinant of altered cardiac lipid, in the pathogenesis of cardiac decompensation is largely unknown. This research focuses on mechanisms invoked by gender, dietary fat, and stress via pressure overload, that alter the balance between mitochondrial oxidation and cellular storage of long chain fatty acids (LCFA) to affect myofilament biochemistry and activity. We will examine gender and estrogen effects on the remodeling of cardiac lipid dynamics in response to pressure overload, focusing on both active and passive components of heart function; the active component being biochemical changes within sarcomeric proteins, due to metabolic signaling, and the passive component being myocardial stiffness due to lipid infiltration. Preliminary data suggest lipid accumulation produces myocardial stiffness, and that gender influences cardiac lipid dynamics and acyl derivatives. We reported reduced triacylglyceride (TAG) turnover and contributions of TAG to mitochondrial oxidation in hypertrophied hearts and find that acyl-derivatives affect myofilament phosphorylation and sensitivity to Ca2+. We plan to combine in vivo measurements of cardiac function and lipid content, with stable isotope kinetics of metabolic flux and myofilament proteomics to address a two-fold hypothesis that: 1) Gender differences, due to estrogen, affect metabolic reprogramming in cardiac hypertrophy with shifts in lipid utilization/storage affecting cardiac function, and 2) that dietary fat, storage (PPAR¿ ovr expression) and uptake (FATP1 overexpression) reveal gender-specific changes in cardiac lipid dynamics, affecting myocardial compliance and sarcomere activity. Aims are: 1) Examine gender and estrogen-dependent differences in lipid utilization/storage dynamics in hearts of male, female, and overiectomized female, non-transgenic (NTG) and MHC-PPAR¿ low-overexpressing (strain 404-4) mice; 2) Test how LCFA uptake, gender and estrogen contribute to the response to pressure overload by determining a) lipid dynamics and consequential effects on myocardial 2-D strains, tissue stiffness and contractility and b) ceramide species and sphingosine production and consequential effects on myofilament phosphorylation, oxidation and Ca-responsiveness in hearts of non-transgenic mice and transgenic mice overexpressing FATP1; 3) Determine the potential for gender-based adaptations in TAG dynamics and LCFA oxidation rates in response to pressure overload, to affect a) myocardial 2-D strains and stiffness through mechanical effects of lipid accumulation and b) sarcomere activity through phosphorylation effects of LCFA-derived intermediates, ceramides and sphingosine, on myofilament sensitivity in MHC-PPAR¿ hearts. The objectives are to elucidate mechanisms for reprogramming cardiac lipid dynamics that affect heart function, thereby identifying strategies for early diagnosis and gender specific-treatment protocols to mitigate the development of cardiomyopathy.