Urocortin 2 promotes hypertrophy and enhances skeletal muscle function through cAMP and insulin/IGF-1 signaling pathways

• Published in: Molecular metabolism (Germany) Vol. 60; p. 101492
• Main Authors: Lautherbach, Natalia, Gonçalves, Dawit A.P., Silveira, Wilian A., Paula-Gomes, Sílvia, Valentim, Rafael Rossi, Zanon, Neusa M., Pereira, Marcelo G., Miyabara, Elen H., Navegantes, Luiz C.C., Kettelhut, Isis C.
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 01.06.2022; Elsevier
• Subjects: Adrenocorticotropic Hormone - metabolism; Adrenocorticotropic Hormone - pharmacology; Animals; cAMP; Corticotropin-Releasing Hormone - metabolism; Fatigue resistance; Hypertrophy; Hypertrophy - metabolism; Insulin - metabolism; Insulin-Like Growth Factor I - metabolism; Mice; Muscle, Skeletal - metabolism; Original; Proto-Oncogene Proteins c-akt - metabolism; Signal Transduction; Urocortin 2; Urocortins - metabolism; Urocortins - pharmacology; Fatigue resistance; Urocortin 2; cAMP; Hypertrophy
• DOI: 10.1016/j.molmet.2022.101492
• ISSN: 2212-8778

Although it is well established that urocortin 2 (Ucn2), a peptide member of the corticotrophin releasing factor (CRF) family, and its specific corticotrophin-releasing factor 2 receptor (CRF2R) are highly expressed in skeletal muscle, the role of this peptide in the regulation of skeletal muscle mass and protein metabolism remains elusive. To elucidate the mechanisms how Ucn2 directly controls protein metabolism in skeletal muscles of normal mice, we carried out genetic tools, physiological and molecular analyses of muscles in vivo and in vitro. Here, we demonstrated that Ucn2 overexpression activated cAMP signaling and promoted an expressive muscle hypertrophy associated with higher rates of protein synthesis and activation of Akt/mTOR and ERK1/2 signaling pathways. Furthermore, Ucn2 induced a decrease in mRNA levels of atrogin-1 and in autophagic flux inferred by an increase in the protein content of LC3-I, LC3-II and p62. Accordingly, Ucn2 reduced both the transcriptional activity of FoxO in vivo and the overall protein degradation in vitro through an inhibition of lysosomal proteolytic activity. In addition, we demonstrated that Ucn2 induced a fast-to-slow fiber type shift and improved fatigue muscle resistance, an effect that was completely blocked in muscles co-transfected with mitogen-activated protein kinase phosphatase 1 (MKP-1), but not with dominant-negative Akt mutant (Aktmt). These data suggest that Ucn2 triggers an anabolic and anti-catabolic response in skeletal muscle of normal mice probably through the activation of cAMP cascade and participation of Akt and ERK1/2 signaling. These findings open new perspectives in the development of therapeutic strategies to cope with the loss of muscle mass. •Ucn2 overexpression promotes muscle growth due to an increase in protein synthesis.•Ucn2 inhibits FoxO activity and autophagic-lysosomal system.•Ucn2-induced skeletal muscle phenotype is dependent on Akt and ERK1/2.•Ucn2 induces a fast-to-slow fiber type shift and improves fatigue resistance.•The increase in muscle fatigue resistance is dependent on ERK1/2.