Role of Pck2 in cardiac fibrosis

项目摘要 心肌梗死后的纤维化重塑涉及几种成纤维细胞表型的暂时发展， 其特征在于高增殖率、分化成肌成纤维细胞和细胞外基质增加 证词这些过程需要代谢需求的大量增加来实现或维持活化的代谢。 成纤维细胞状态然而，成纤维细胞如何满足这些高代谢需求的阶段，以及是否 特定的代谢步骤可能是抗纤维化的目标仍然不清楚。先前的研究表明，促纤维化 刺激物增加成纤维细胞中分解代谢活性并降低糖酵解或氧化磷酸化 减少肌成纤维细胞分化。这些代谢途径不仅对ATP的产生很重要， 而且它们在细胞结构单元和分泌蛋白质的合成中的作用。特别是几 糖酵解中间体作为两亲代谢物，能够进入负责降解的途径。 核苷酸、磷脂和氨基酸的新合成。这些生物合成途径可能特别 这在纤维化反应中很重要，因为活化的成纤维细胞需要更高的合成代谢输出来提供 用于细胞分裂和ECM分泌的生物分子构建块。我们的初步数据表明， 在活化的成纤维细胞中，致纤维化酶磷酸烯醇式丙酮酸羧激酶2（Pck 2）上调。 这种酶被定位为协调合成代谢过程，因为它可以从克雷布斯循环中输送碳 中间池到3-碳糖酵解池，从而增加了几种生物合成的前体 途径。我们还发现谷氨酰胺酶在活化的成纤维细胞中上调，这可以增加谷氨酰胺- 为克雷布斯循环库衍生碳，然后可用于Pck 2。表明其对成纤维细胞的重要性 功能，Pck 2缺失降低成纤维细胞增殖并似乎影响肌成纤维细胞的标志物， 表明它是一种可促进或维持活化的成纤维细胞表型的关键酶。我们提出 pck 2是纤维化的基本调节因子，通过满足生物合成的条件来调节成纤维细胞活化， 需要增殖或ECM沉积。然而，实际上没有人知道如何 成纤维细胞生物合成途径对纤维化刺激的反应或Pck 2如何影响成纤维细胞 代谢和心脏纤维化。为了解决这些知识差距，我们将：（1）阐明pck 2如何影响 心肌成纤维细胞代谢;和（2）确定Pck 2对成纤维细胞活化和MI诱导的心肌细胞凋亡的影响。 心脏重塑这个项目将产生必要的基本知识，了解成纤维细胞如何 代谢调节心脏损伤后的纤维化重塑。

Project Summary Fibrotic remodeling after myocardial infarction involves temporal development of several fibroblast phenotypes, characterized by high proliferation rates, differentiation into myofibroblasts, and heightened extracellular matrix deposition. These processes require large increases in metabolic demand to achieve or maintain the activated fibroblast state. Nevertheless, how fibroblasts meet these phases of high metabolic demand and whether particular metabolic steps could be antifibrotic targets remains unclear. Previous studies indicate that profibrotic stimuli augment catabolic activity in fibroblasts and that lowering either glycolysis or oxidative phosphorylation diminishes myofibroblast differentiation. These metabolic pathways are important not only for ATP production, but also for their role in the synthesis of cellular building blocks and secreted proteins. In particular, several glycolytic intermediates serve as amphibolic metabolites capable of entering into pathways responsible for de novo nucleotide, phospholipid, and amino acid synthesis. These biosynthetic pathways could be particularly important in the fibrotic response because activated fibroblasts require higher anabolic output to provide biomolecular building blocks for cell division and ECM secretion. Our preliminary data suggest that the gluconeogenic enzyme, phosphoenolpyruvate carboxykinase 2 (Pck2), is upregulated in activated fibroblasts. This enzyme is positioned to coordinate anabolic processes because it can deliver carbon from the Krebs cycle intermediate pool to the 3-carbon glycolytic pool, thereby increasing precursors for several biosynthetic pathways. We also find glutaminase to be upregulated in activated fibroblasts, which could augment glutamine- derived carbon for the Krebs cycle pool, which is then available to Pck2. Suggestive of its importance to fibroblast function, Pck2 deletion decreases fibroblast proliferation and appears to affect markers of myofibroblasts, indicating that it is a critical enzyme that may facilitate or uphold the activated fibroblast phenotype. We propose that Pck2 is a fundamental regulator of fibrosis that regulates fibroblast activation by meeting the biosynthetic demands required for proliferation or ECM deposition. Nevertheless, virtually nothing is known about how biosynthetic pathways change in fibroblasts in response to fibrogenic stimuli or how Pck2 influences fibroblast metabolism and cardiac fibrosis. To address these gaps in knowledge, we will: (1) elucidate how Pck2 influences cardiac fibroblast metabolism; and (2) determine the influence of Pck2 on fibroblast activation and MI-induced cardiac remodeling. This project will yield fundamental knowledge necessary for understanding how fibroblast metabolism modulates fibrotic remodeling after cardiac injury.