Genevieve C. Sparagna PhD1, Hailey L. Chapman1, Valerie L. Warkins1, Elisabeth K. Phillips BS1, Anastacia M. Garcia PhD2, Danielle Jeffrey BS1, Iñigo San-Millán PhD1, Carmen C. Sucharov PhD1, Shelley D. Miyamoto MD2, Brian L. Stauffer MD1,3, and Kathryn C. Chatfield MD, PhD2
1Department of Medicine/Division of Cardiology, University of Colorado School of Medicine, Aurora, Colorado
2Department of Pediatrics, University of Colorado School of Medicine, Children’s Hospital Colorado, Aurora, Colorado
3Division of Cardiology, Denver Health Medical Center, Denver, Colorado
Highly oxidative mammalian tissues such as heart and skeletal muscle are characterized by mitochondrial phospholipid cardiolipin (CL) that is highly enriched with linoleate side chains (L4CL), whereas highly glycolytic tissues have higher content of CL with oleate side chains (OL4CL, and OL3L1CL). Based on this observation, CL is an attractive therapeutic target for fatty acid oxidation disorders. Previous studies have shown that L4CL is requisite for inner mitochondrial membrane structure that facilitates electron transport chain efficiency (OxPhos), minimizes production of reactive oxygen species (ROS), and promotes beta-oxidation. Using a Sprague-Dawley rat model, we show that a developmental shift in cardiac CL profiles occurs as the neonatal rat ages to maturity, with OL-containing CLs being replaced with L4CL. The shift from OL to L-rich CL is correlated with a 6-fold increase in CPTI and an 8-fold increase in CPTII enzyme activities. We show that glycolytic capacity is higher in cultured rat ventricular myocytes (RVMs) from neonatal animals, with an age-dependent shift toward beta-oxidation and OxPhos in the juvenile and adult RVMs. Furthermore, we show that a metabolic shift can be induced by providing RVMs (of any stage) with OL or L to shift the CL milieu toward a more OL or L-enriched phenotype. Neonatal and adult RVM CL profiles can be altered in this way to promote a more glycolytic or oxidative phenotype, respectively. Additionally, we show that OL-treated RVMs have higher ROS production.
Finally, D-lactate treatment of RVMs is shown to result in a shift toward OL-enriched CL with a concurrent decrease in OxPhos, beta-oxidation, with increased ROS production. Our results show that L-enrichment of cardiac CL is requisite for efficiency of OxPhos and beta oxidation in the heart, with minimization of ROS production. This shift is modulatable with provision of precursors for CL biosynthesis or lactate to induce the corresponding metabolic phenotype.