Transendothelial transport and CD36 in the dysregulated lipid trafficking of failing hearts

项目摘要： 这项拟议中的研究探讨了心脏衰竭时脂质代谢失调的机制， 长链脂肪酸（LCFA）从循环到代谢的动态过程， 心肌细胞（CM）。我们将探讨内皮细胞（EC）向CM输送LCFA的作用以及CM的发生率。 在心力衰竭小鼠模型中，CM在不良代谢重塑中的LCFA摄取， 心脏衰竭的代谢缺陷心脏依靠LCFA氧化，高达70%的燃料，以满足ATP 需求LCFA也被酯化成中性甘油三酯（TG）库和生理活性酰基- 衍生物.在衰竭的心脏中，LCFA氧化减少，脂质谱变得有毒。我们展示了一个 在衰竭的心脏中，中心LCFA代谢物酰基辅酶A的减少是有害的， ACSL 1产生的CoA改善代谢状态并减轻功能下降。心脏的13 C NMR 揭示了13 C LCFA进入TG的指数分量，其反映了LCFA摄取率，并且是敏感的 LCFA转运蛋白CD 36的活性。LCFA摄取也通过代谢捕获加速， 通过ACSL 1将LCFA酯化为酰基辅酶A，这是一个性别依赖性过程。在小鼠身上进行的实验- 具体而言，EC（EC-CD 36 KO）和CM（CM-CD 36 KO）中的CD 36缺失将支持研究 在竞争性细胞内，EC向CM递送LCFA和CM摄取LCFA对LCFA代谢的不同作用 途径，包括在衰竭的心脏中有害的神经酰胺形成。LCFA摄取的潜在差异， 两种主要生理来源，白蛋白结合的LCFA和脂蛋白结合的TG之间的代谢将 被研究。假设：a）EC CD 36依赖性和非依赖性跨内皮细胞的贡献 LCFAs转运到正常和患病心脏的CM中决定了LCFAs的代谢命运， B）在CM CD 36活性中存在性别依赖性差异，并取决于LCFA来源; LCFA的转运和通过酯化将LCFA捕获到CM中，这有助于LCFA的脂毒性特征。 心脏衰竭具体目标是：1。阐明EC CD 36对LCFA跨内皮转运的贡献 在雄性与雌性EC-CD 36 KO小鼠的正常和衰竭心脏中的摄取动力学和代谢命运。2. 区分CM-CD 36和EC对正常人心脏LCFA摄取动力学和代谢命运的贡献 以及雄性与雌性CM-CD 36 KO小鼠的失败热。3.阐明CD 36转运的相互作用， 通过ACSL 1对正常和衰竭心脏中LCFA使用的代谢捕获，通过沉默心脏中的CD 36， ACSL 1（MHC-ACSL 1 J3）的低过表达，以及来自交叉、MHC-ASCL 1xEC-CD 36 KO和 MHC-ASCL 1xCM-CD 36 KO小鼠。4.区分EC-CD 36和CM-CD 36对LCFA摄取的贡献 正常和衰竭心脏中白蛋白结合源与乳糜微粒结合源的速率和代谢 型、EC-CD 36 KO和CM-CD 36 KO小鼠。结果将提供分子事件的独特信息 调节脂质含量作为解决衰竭心脏代谢失衡的新目标。

Project Summary: The proposed research explores mechanisms of dysregulated lipid metabolism in failing hearts within the dynamic processes of long chain fatty acid (LCFA) delivery from the circulation to metabolism in the cardiomyocyte (CM). We will explore the roles of LCFA delivery by endothelial cells (EC) to CMs and rates of LCFA uptake by CMs in adverse metabolic remodeling in a mouse model of heart failure that recapitulates key metabolic defects in failing human hearts. Hearts rely on LCFA oxidation, up to 70% of fuels, to meet ATP demand. LCFA are also esterified into the neutral triglyceride (TG) pool and into physiologically active acyl- derivatives. In failing hearts, LCFA oxidation is reduced and the lipid profile becomes toxic. We have shown a reduction in the central LCFA metabolite, acyl-CoA, in failing hearts is detrimental, and increased acyl CoA production by ACSL1 improves metabolic state and mitigates functional decline. 13C NMR of hearts revealed an exponential component of 13C LCFA entry into TG that reflects LCFA uptake rate and is sensitive to activity of the LCFA transporter, CD36. LCFA uptake is also accelerated by metabolic trapping via esterification of LCFA to acyl-CoA by ACSL1, a process that is sex-dependent. Experiments on mice with cell- specific, CD36 deletion in ECs (EC-CD36 KO) and CMs (CM-CD36 KO) will support the objective to study the separate roles of LCFA delivery by ECs to CMs and uptake by CMs on LCFA metabolism within competing pathways, including deleterious ceramide formation in failing hearts. Potential differences in LCFA uptake and metabolism between two primary physiological sources, albumin-bound LCFA and lipoprotein-bound TG, will be studied. The hypothesis is: a) the contributions of EC CD36-dependent and independent transendothelial transport of LCFAs into CMs of normal and diseased hearts determine the metabolic fate of LCFAs, separate from CM CD36 activity, and depend on the LCFA source; b) there are sex-dependent differences in both CD36 transport of LCFA and trapping of LCFAs into CMs via esterification that contribute to the lipotoxic profile of failing hearts. Specific aims are: 1. Elucidate EC CD36 contributions to transendothelial transport of LCFA uptake kinetics and metabolic fate in normal and failing hearts of male vs. female EC-CD36 KO mice. 2. Distinguish CM-CD36 from EC contributions to LCFA uptake kinetics and metabolic fate in hearts of normal and failing heats of male vs. female CM-CD36 KO mice. 3. Elucidate reciprocal effects of CD36 transport and metabolic trapping by ACSL1 on LCFA use in normal and failing hearts, by silencing of CD36 in hearts having low overexpression of ACSL1 (MHC-ACSL1 J3) and in hearts from crossed, MHC-ASCL1xEC-CD36 KO and MHC-ASCL1xCM-CD36 KO mice. 4. Distinguish contributions of EC-CD36 and CM-CD36 to LCFA uptake rates and metabolism from albumin-bound vs. chylomicron-bound sources in normal and failing hearts of wild type, EC-CD36 KO, and CM-CD36 KO mice. Outcomes will provide unique information on molecular events modulating lipid content as new targets to resolve metabolic imbalances in failing hearts.