Effects of extracellular orotic acid on acute contraction-induced adaptation patterns in C2C12 cells
- 266 Downloads
Dietary administration of orotic acid (OA), an intermediate in the pyrimidine biosynthetic pathway, is considered to provide a wide range of beneficial effects, including cardioprotection and exercise adaptation. Its mechanisms of action, when applied extracellularly, however, are barely understood. In this study, we evaluated potential effects of OA on skeletal muscle using an in vitro contraction model of electrically pulse-stimulated (EPS) C2C12 myotubes. By analyzing a subset of genes representing inflammatory, metabolic, and structural adaptation pathways, we could show that OA supplementation diminishes the EPS-provoked expression of inflammatory transcripts (interleukin 6, Il6; chemokine (C-X-C Motif) ligand 5, Cxcl5), and attenuated transcript levels of nuclear receptor subfamily 4 group A member 3 (Nr4A3), early growth response 1 (Egr1), activating transcription factor 3 (Atf3), and fast-oxidative MyHC-IIA isoform (Myh2). By contrast, OA had no suppressive effect on the pathogen-provoked inflammatory gene response in skeletal muscle cells, as demonstrated by stimulation of C2C12 myotubes with bacterial LPS. In addition, we observed a suppressive effect of OA on EPS-induced phosphorylation of AMP-activated protein kinase (AMPK), whereas EPS-triggered phosphorylation/activation of the mammalian target of rapamycin (mTOR) was not affected. Finally, we demonstrate that OA positively influences glycogen levels in EP-stimulated myotubes. Taken together, our results suggest that in skeletal muscle cells, OA modulates both the inflammatory and the metabolic reaction provoked by acute contraction. These results might have important clinical implications, specifically in cardiovascular and exercise medicine.
KeywordsOrotic acid Electrical pulse stimulation Skeletal muscle contraction
Work in the authors’ laboratory was furthermore supported by grants from the Monika-Kutzner-Stiftung, Berlin, Germany, and from the Else-Übelmesser-Stiftung, Tübingen, Germany.
This work was supported by a grant from Wörwag Pharma, Böblingen, Germany.
- 9.Desler C, Lykke A, Rasmussen LJ (2010) The effect of mitochondrial dysfunction on cytosolic nucleotide metabolism. J Nucleic Acids 24:701518Google Scholar
- 21.Fernández-Verdejo R, Vanwynsberghe AM, Essaghir A, Demoulin JB, Hai T, Deldicque L, Francaux M (2017) Activating transcription factor 3 attenuates chemokine and cytokine expression in mouse skeletal muscle after exercise and facilitates molecular adaptation to endurance training. FASEB J 31:840–851CrossRefGoogle Scholar
- 32.Whitham M, Chan MH, Pal M, Matthews VB, Prelovsek O, Lunke S, El-Osta A, Broenneke H, Alber J, Brüning JC, Wunderlich FT, Lancaster GI, Febbraio MA (2012) Contraction-induced interleukin-6 gene transcription in skeletal muscle is regulated by c-Jun terminal kinase/activator protein-1. J Biol Chem 287:10771–10779CrossRefGoogle Scholar
- 35.Hoffman NJ, Parker BL, Chaudhuri R, Fisher-Wellman KH, Kleinert M, Humphrey SJ, Yang P, Holliday M, Trefely S, Fazakerley DJ, Stöckli J, Burchfield JG, Jensen TE, Jothi R, Kiens B, Wojtaszewski JF, Richter EA, James DE (2015) Global phosphoproteomic analysis of human skeletal muscle reveals a network of exercise-regulated kinases and AMPK substrates. Cell Metab 22:922–935CrossRefGoogle Scholar
- 45.Philp A, Hargreaves M, Baar K (2012) More than a store: regulatory roles for glycogen in skeletal muscle adaptation to exercise. Am J Physiol Endocrinol Metab 302:E1343-E1351Google Scholar