Abstract 517: Glutaminolysis is Required to Initiate Myofibroblast Differentiation and Persistence During Stress

• Published in: Circulation research 2019-08, Vol.125 (Suppl_1)
• Main Authors: Gibb, Andrew A, Lombardi, Alyssa A, Murray, Emma K, Tan, Yinfei, Lorkiewicz, Pawel K, Huynh, Anh T, Kolmetzky, Devin W, Arany, Zolt, Kelly, Daniel P, Margulies, Kenneth B, Hill, Bradford G, Elrod, John W
• Format: Article
• Language: English
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/res.125.suppl_1.517

Abstract only Cardiac fibrosis occurs in ischemic heart failure, genetic cardiomyopathies, diabetes, and aging. While initially considered reparative, resident cardiac fibroblasts (CFs) activation/differentiation to myofibroblasts provide contractile and integral support; however, persistent activation leads to progressive cardiac dysfunction and maladaptive remodeling. Recent reports implicate acute and/or chronic changes in metabolism as a central driver for many cellular differentiation programs. Indeed, metabolite bioavailability is directly linked to the activity of epigenetic-modifying enzymes implicated in lineage commitment and differentiation. We recently identified αKG-dependent lysine demethylases as key contributors to myofibroblast formation. Here, TGFβ stimulated fibroblasts isolated from adult mouse hearts were subjected to next-gen sequencing methodologies (RNA-seq, ATAC-seq, and RRBS-seq) to identify dynamic modifications in chromatin architecture and DNA accessibility at gene loci critical to the myofibroblast gene program. Utilizing unbiased and stable-isotope metabolomics, we correlated chromatin remodeling with a significant decrease in abundance/utilization of s-adenosylmethionine, the methyl donor for cytosine and histone methylation. In addition, a significant increase in αKG abundance driven by enhanced glutaminolysis was observed. To investigate the significance of glutaminolysis and enhanced αKG biosynthesis, we treated CFs with a glutaminase inhibitor (CB-839) and evaluated differentiation. Treatment with CB-839 in the presence of TGFβ prevented activation of the fibrotic gene program (RT-qPCR) and myofibroblast formation. Furthermore, following TGFβ-induced differentiation, inhibition of glutaminolysis was sufficient to revert activated myofibroblasts to a quiescent non-fibrotic phenotype, even during sustained stress. Importantly, this phenomenon is reproducible in CFs derived from human HF patients. Collectively, these results suggest a primary role for metabolism in not only initiating differentiation, but also the persistence of myofibroblasts, potentially through epigenetic-dependent gene transcription, providing new therapeutic targets to treat fibrosis.