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，尽管心肌细胞的收缩能力没有固有的差异。在病理生理应激过程中，人类和动物的脂质动力学都表现出性别差异。然而，性别作为心脏脂质改变的决定因素，在心脏失代偿的发病机制中的作用在很大程度上是未知的。这项研究的重点是性别、饮食脂肪和压力通过压力超负荷启动的机制，这些机制改变了线粒体氧化和细胞存储长链脂肪酸(LCFA)之间的平衡，从而影响肌丝的生化和活性。我们将研究性别和雌激素在压力超负荷下心脏脂质动力学重塑中的作用，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导致的肌节蛋白内的生化变化，被动成分是由于脂质渗透导致的心肌僵硬。初步数据表明，脂质堆积会产生心肌僵硬，性别会影响心脏脂质动力学和酰基衍生物。我们报道了肥厚心脏中三酰甘油(TAG)转换率的降低和TAG对线粒体氧化的贡献，并发现酰基衍生物影响了肌丝的磷酸化和对钙的敏感性。我们计划将体内心脏功能和脂质含量的测量与代谢流量的稳定同位素动力学和肌丝蛋白质组学相结合，以解决两个假设：1)由于雌激素，性别差异影响心肌肥厚的代谢重编程，脂质利用/储存的变化影响心脏功能；2)饮食脂肪、储存(PPAR？ovr表达)和摄取(FATP1过度表达)揭示心脏脂质动力学的性别差异，影响心肌顺应性和肌小球活性。目的是：1)检测雄性、雌性和切除过多的雌性、非转基因(NTG)和MHC-PPAR低过表达(品系404-4)小鼠心脏中脂类利用/储存动力学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超负荷反应的作用，方法是：a)脂质动力学和相应的对心肌二维应变、组织僵硬和收缩的影响；b)神经酰胺种类和鞘氨醇产生以及对非转基因小鼠和过度表达FATP1的转基因小鼠心脏肌丝磷酸化、氧化和钙反应的影响；3)确定压力超负荷对TAG动力学和LCFA氧化率的性别适应性的可能性，a)通过脂质堆积的机械效应影响心肌二维应变和硬度，以及b)通过LCFA衍生的中间产物、神经酰胺和鞘氨醇的磷酸化效应影响肌节活性，影响MHC-PPAR？心脏的肌丝敏感性。其目的是阐明影响心脏功能的心脏脂质动力学重新编程的机制，从而确定早期诊断的策略和针对性别的治疗方案，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.