Xiu-Ying Yang1,2, Margaret C L Tse3, Xiang Hu2, Wei-Hua Jia1, Guan-Hua Du4, Chi Bun Chan5. 1. State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, Beijing, China. 2. Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA. 3. School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China. 4. State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica of Peking Union Medical College, Beijing, Chinadugh@imm.ac.cn. 5. School of Biological Sciences, the University of Hong Kong, 5N10 Kadoorie Biological Sciences Building, Hong Kong, China.
Abstract
BACKGROUND/AIMS: Fibronectin type III domain-containing protein 5 (FNDC5), also known as irisin, is a myokine secreted from muscle in response to exercise. However, the molecular mechanisms that regulate FNDC5 expression and the functional significance of irisn in skeletal muscle remain unknown. In this study, we explored the potential pathways that induce FNDC5 expression and delineated the metabolic effects of irisin on skeletal muscle. METHODS: C2C12 myotubes were treated with drugs at various concentrations and durations. The expression and activation of genes were measured by real-time polymerase chain reaction (qRT-PCR) and Western blotting. Oxidative phosphorylation was quantified by measuring the oxygen consumption rate (OCR). RESULTS: We found that the exercise-mimicking treatment (cAMP, forskolin and isoproterenol) increased Fndc5 expression in C2C12 myotubes. CREB over-expressed C2C12 myotubes displayed higher Fndc5 expression. CREB over-expression also promoted peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) expression. PGC-1α-induced Fndc5 expression was blocked when the dominant negative form of CREB (S133A) was present. PGC-1α mutation (S570A) also decreased Fndc5 expression. Immunoprecipitation showed that overexpressed PGC-1α complexed with CREB in HEK293 cells. C2C12 myotubes treated with forskolin also increased endogenous CREB and PGC-1α binding. Functionally, irisin treatment increased mitochondrial respiration, enhanced ATP production, promoted fatty acid oxidation but decreased glycolysis in myotubes. CONCLUSION: Our observation indicates that cAMP-mediated PGC-1α/CREB interaction triggers Fndc5 expression, which acts as an autocrine/paracrine to shape the metabolic phenotype of myotubes.
BACKGROUND/AIMS: Fibronectin type III domain-containing protein 5 (FNDC5), also known as irisin, is a myokine secreted from muscle in response to exercise. However, the molecular mechanisms that regulate FNDC5 expression and the functional significance of irisn in skeletal muscle remain unknown. In this study, we explored the potential pathways that induce FNDC5 expression and delineated the metabolic effects of irisin on skeletal muscle. METHODS: C2C12 myotubes were treated with drugs at various concentrations and durations. The expression and activation of genes were measured by real-time polymerase chain reaction (qRT-PCR) and Western blotting. Oxidative phosphorylation was quantified by measuring the oxygen consumption rate (OCR). RESULTS: We found that the exercise-mimicking treatment (cAMP, forskolin and isoproterenol) increased Fndc5 expression in C2C12 myotubes. CREB over-expressed C2C12 myotubes displayed higher Fndc5 expression. CREB over-expression also promoted peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) expression. PGC-1α-induced Fndc5 expression was blocked when the dominant negative form of CREB (S133A) was present. PGC-1α mutation (S570A) also decreased Fndc5 expression. Immunoprecipitation showed that overexpressed PGC-1α complexed with CREB in HEK293 cells. C2C12 myotubes treated with forskolin also increased endogenous CREB and PGC-1α binding. Functionally, irisin treatment increased mitochondrial respiration, enhanced ATP production, promoted fatty acid oxidation but decreased glycolysis in myotubes. CONCLUSION: Our observation indicates that cAMP-mediated PGC-1α/CREB interaction triggers Fndc5 expression, which acts as an autocrine/paracrine to shape the metabolic phenotype of myotubes.
Authors: Natalia Lautherbach; Dawit A P Gonçalves; Wilian A Silveira; Sílvia Paula-Gomes; Rafael Rossi Valentim; Neusa M Zanon; Marcelo G Pereira; Elen H Miyabara; Luiz C C Navegantes; Isis C Kettelhut Journal: Mol Metab Date: 2022-04-04 Impact factor: 8.568