Wells Collin K, Nguyen Daniel C, Brainard Robert E, McNally Lindsey A, De Silva Maleesha, Brittian Kenneth R, Garrett Lauren, Taylor Madison S, Martinez-Ondaro Yania, Howard Caitlin, Suluru Snigdha, Dassanayaka Sujith, Mohamed Tamer M A, Singhal Richa, Gibb Andrew A, Lorkiewicz Pawel K, Moore Joseph B, Jones Steven P, Hill Bradford G
Center for Cardiometabolic Science, Christina Lee Brown Envirome Institute, University of Louisville School of Medicine, Louisville, KY, USA; Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY, USA.
Center for Cardiometabolic Science, Christina Lee Brown Envirome Institute, University of Louisville School of Medicine, Louisville, KY, USA; Department of Physiology, University of Louisville, Louisville, KY, USA.
J Mol Cell Cardiol. 2025 Jul 10;206:11-26. doi: 10.1016/j.yjmcc.2025.07.005.
Fibroblasts are crucial for cardiac repair after myocardial infarction (MI). In response to signaling cues, they differentiate to phenotypes with robust capacities to synthesize and secrete extracellular matrix (ECM) and signaling molecules. Although activated fibroblast phenotypes are associated with pronounced changes in metabolism, it remains unclear how the metabolic network upholds the effector functions of fibroblasts in the infarcted heart. We found that two enzymes that could facilitate a phosphoenolpyruvate cycle, i.e. pyruvate kinase muscle isoform 2 (PKM2) and phosphoenolpyruvate carboxykinase 2 (PCK2), are elevated in the heart after MI. Although Pck2 deletion had no effect on post-MI remodeling, fibroblast-specific switching of Pkm2 to Pkm1 (fbPkm2 → 1) mitigated ventricular dilation, wall thinning, and losses in ejection fraction caused by MI. Despite these salutary effects, fbPkm2 → 1 switching did not alter cardiac fibrosis in vivo, nor did it affect collagen production, cytokine or chemokine secretion, myofibroblast differentiation markers, or transcriptional regulation in vitro. Nevertheless, Pkm2 → 1 splice variant switching increased myofibroblast contractile activity as well as influenced the metabolic phenotype of fibroblasts, as shown by increased pyruvate kinase activity, higher mitochondrial respiratory capacity, and elevation in glycolytic intermediate abundance. Despite these changes, Pkm2 → 1 switching had relatively minor effects on glucose carbon fate, as determined by stable isotope-resolved metabolomics. Nevertheless, these metabolic data demonstrate that cardiac fibroblasts exhibit minimal glucose-supported de novo glycine synthesis in vitro, yet possess high hexosamine and glucuronate biosynthetic pathway activity. Collectively, these findings reveal that fibroblast PKM isoforms influence post-MI remodeling, highlighting pyruvate kinase as a potential therapeutic target.
成纤维细胞对心肌梗死后的心脏修复至关重要。响应信号线索，它们分化为具有强大合成和分泌细胞外基质（ECM）及信号分子能力的表型。尽管活化的成纤维细胞表型与代谢的显著变化相关，但尚不清楚代谢网络如何维持梗死心脏中成纤维细胞的效应器功能。我们发现，两种可促进磷酸烯醇丙酮酸循环的酶，即丙酮酸激酶肌肉亚型2（PKM2）和磷酸烯醇丙酮酸羧激酶2（PCK2），在心肌梗死后心脏中升高。尽管Pck2缺失对心肌梗死后重塑无影响，但成纤维细胞特异性地将Pkm2转换为Pkm1（fbPkm2→1）可减轻心肌梗死引起的心室扩张、壁变薄和射血分数降低。尽管有这些有益作用，但fbPkm2→1转换在体内并未改变心脏纤维化，在体外也未影响胶原蛋白产生、细胞因子或趋化因子分泌、肌成纤维细胞分化标志物或转录调控。然而，Pkm2→1剪接变体转换增加了肌成纤维细胞收缩活性，并影响了成纤维细胞的代谢表型，表现为丙酮酸激酶活性增加、线粒体呼吸能力增强以及糖酵解中间产物丰度升高。尽管有这些变化，但通过稳定同位素分辨代谢组学确定，Pkm
