Effect of sodium 4-phenylbutyrate on clenbuterol-mediated muscle growth

Brown, David M.; Jones, Sarah; Daniel, Zoe C.T.R.; Brearley, Madelaine C.; Lewis, Jo E.; Ebling, Francis J.P.; Parr, Tim; Brameld, John M.

Abstract

Previously, we highlighted induction of an integrated stress response (ISR) gene program in skeletal muscle of pigs treated with a beta-adrenergic agonist. Hence we tested the hypothesis that the ER-stress inhibitor, sodium 4-phenylbutyrate (PBA), would inhibit Clenbuterol-mediated muscle growth and reduce expression of genes that are known indicators of an ISR in mice. Clenbuterol (1mg/kg/day) administered to C57BL6/J mice for 21 days increased body weight (p<0.001), muscle weights (p<0.01), and muscle fibre diameters (p<0.05). Co-administration of PBA (100mg/kg/day) did not alter the Clenbuterol-mediated phenotype, nor did PBA alone have any effects compared to that of the vehicle treated mice. Clenbuterol increased skeletal muscle mRNA expression of phosphoserine amino transferase 1 (PSAT1, p<0.001) and cyclophillin A (p<0.01) at day 3, but not day 7. Clenbuterol decreased mRNA expression of activating transcription factor (ATF) 4 and ATF5 at day 3 (p<0.05) and day 7 (p<0.01), X-box binding protein 1 (XBP1) variant 2 mRNA at day 3 only (p<0.01) and DNA damage inducible transcript 3 (DDIT3/CHOP) mRNA at day 7 only (p<0.05). Co-administration of PBA had no effect on Clenbuterol-induced changes in skeletal muscle gene expression. In contrast, treatment of C2C12 myotubes with 5mM PBA (8hr) attenuated the thapsigargin-induced ISR gene program. Prolonged (24-48hr) treatment with PBA caused atrophy (p<0.01), reduced neoprotein synthesis (p<0.0001) and decreased expression of myogenin and fast myosin heavy chain genes (p<0.01), indicating an inhibition of myogenic differentiation. In summary, Clenbuterol did not induce an ISR gene program in mouse muscle. On the contrary, it reduced expression of a number of ISR genes, but it increased expression of PSAT1 mRNA. Co-administration of PBA had no effect on Clenbuterol-mediated muscle growth or gene expression in mice, whereas PBA did inhibit thapsigargin-induced ISR gene expression in cultured C2C12 cells and appeared to inhibit myogenic differentiation, independent of altering ISR gene expression.

Citation

Brown, D. M., Jones, S., Daniel, Z. C., Brearley, M. C., Lewis, J. E., Ebling, F. J., Parr, T., & Brameld, J. M. (2018). Effect of sodium 4-phenylbutyrate on clenbuterol-mediated muscle growth. PLoS ONE, 13(7), Article e0201481. https://doi.org/10.1371/journal.pone.0201481

• Journal Article Type: Article
• Acceptance Date: Jul 19, 2018
• Publication Date: Jul 27, 2018
• Deposit Date: Jul 25, 2018
• Publicly Available Date: Jul 27, 2018
• Journal: PLoS ONE
• Electronic ISSN: 1932-6203
• Publisher: Public Library of Science
• Peer Reviewed: Peer Reviewed
• Volume: 13
• Issue: 7
• Article Number: e0201481
• DOI: https://doi.org/10.1371/journal.pone.0201481
• Keywords: Integrated stress response, beta-adrenergic agonist, ER-stress, hypertrophy, atrophy, activating transcription factor
• Public URL: https://nottingham-repository.worktribe.com/output/947941
• Publisher URL: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201481
• Contract Date: Jul 25, 2018