Cardiomyocytes disrupt pyrimidine biosynthesis in nonmyocytes to regulate heart repair
Shen Li, … , Caius G. Radu, Arjun Deb
Shen Li, … , Caius G. Radu, Arjun Deb
Published November 23, 2021
Citation Information: J Clin Invest. 2022;132(2):e149711. https://doi.org/10.1172/JCI149711.
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Research Article Cardiology

Cardiomyocytes disrupt pyrimidine biosynthesis in nonmyocytes to regulate heart repair

Abstract

Various populations of cells are recruited to the heart after cardiac injury, but little is known about whether cardiomyocytes directly regulate heart repair. Using a murine model of ischemic cardiac injury, we demonstrate that cardiomyocytes play a pivotal role in heart repair by regulating nucleotide metabolism and fates of nonmyocytes. Cardiac injury induced the expression of the ectonucleotidase ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), which hydrolyzes extracellular ATP to form AMP. In response to AMP, cardiomyocytes released adenine and specific ribonucleosides that disrupted pyrimidine biosynthesis at the orotidine monophosphate (OMP) synthesis step and induced genotoxic stress and p53-mediated cell death of cycling nonmyocytes. As nonmyocytes are critical for heart repair, we showed that rescue of pyrimidine biosynthesis by administration of uridine or by genetic targeting of the ENPP1/AMP pathway enhanced repair after cardiac injury. We identified ENPP1 inhibitors using small molecule screening and showed that systemic administration of an ENPP1 inhibitor after heart injury rescued pyrimidine biosynthesis in nonmyocyte cells and augmented cardiac repair and postinfarct heart function. These observations demonstrate that the cardiac muscle cell regulates pyrimidine metabolism in nonmuscle cells by releasing adenine and specific nucleosides after heart injury and provide insight into how intercellular regulation of pyrimidine biosynthesis can be targeted and monitored for augmenting tissue repair.

Authors

Shen Li, Tomohiro Yokota, Ping Wang, Johanna ten Hoeve, Feiyang Ma, Thuc M. Le, Evan R. Abt, Yonggang Zhou, Rimao Wu, Maxine Nanthavongdouangsy, Abraham Rodriguez, Yijie Wang, Yen-Ju Lin, Hayato Muranaka, Mark Sharpley, Demetrios T. Braddock, Vicky E. MacRae, Utpal Banerjee, Pei-Yu Chiou, Marcus Seldin, Dian Huang, Michael Teitell, Ilya Gertsman, Michael Jung, Steven J. Bensinger, Robert Damoiseaux, Kym Faull, Matteo Pellegrini, Aldons J. Lusis, Thomas G. Graeber, Caius G. Radu, Arjun Deb

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Figure 8

CFs treated with ENPP1+ATP (MCndM) exhibit decreased pyrimidine levels.

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CFs treated with ENPP1+ATP (MCndM) exhibit decreased pyrimidine levels. ...
(A) LC/MS-MS demonstrating decreased levels of intracellular pyrimidine nucleotides but not (B) purine nucleotides in CFs treated with ENPP1+ATP MCndM (n = 6). (C) CFs treated with vehicle MCndM or ENPP1+ATP MCndM in the presence of uridine, deoxycytidine, or both demonstrating (D) cell death (arrowheads) in CFs treated with ENPP1+ATP MCndM, but rescue of cell death (unfilled arrowheads) following addition of uridine, deoxycytidine, or both. Scale bar: 50 μm. (E) Flow cytometry to demonstrate effects on cell death following addition of uridine or deoxycytidine to CFs treated with ENPP1+ATP MCndM (n = 6). (F) Effect of adding deoxycytidine and deoxycytidine kinase inhibitor (dCKi) to CFs treated with ENPP1+ATP MCndM is a loss of rescue of deoxycytidine in the presence of dCKi (unfilled and filled arrowheads) and (G) quantitation of cell death (n = 5). Scale bar: 50 μm. (H) Outline of critical steps of pyrimidine biosynthesis. (I) Heatmap demonstrating differential expression of metabolites in pyrimidine biosynthetic pathway between CFs treated with vehicle MCndM and those treated with ENPP1+ATP MCndM (n = 3). (J) Rescue of cell death following addition of OMP to CFs treated with ENPP1+ATP MCndM (filled and unfilled arrowheads) and (K) quantitation of cell death (n = 4). Scale bar: 50 μm. (L) Effect on cell death following addition of DHODH inhibitor brequinar (filled arrowheads) to disrupt pyrimidine biosynthesis and rescue with uridine (unfilled arrowheads). (M) Flow cytometry to determine effects of brequinar on cell death and rescue by uridine (n = 5). Scale bar: 50 μm. Data are represented as mean ± SEM.**P < 0.01; *P < 0.05, 2-tailed Student’s t test, (B, I) or ordinary 1-way ANOVA with Tukey’s multiple comparison test (E, G, K, and M).