GH-Releasing Hormone Promotes Survival and Prevents TNF-α-Induced Apoptosis and Atrophy in C2C12 Myotubes

Endocrinology. 2015 Sep;156(9):3239-52. doi: 10.1210/EN.2015-1098. Epub 2015 Jun 25.

Abstract

Skeletal muscle atrophy is a consequence of different chronic diseases, including cancer, heart failure, and diabetes, and also occurs in aging and genetic myopathies. It results from an imbalance between anabolic and catabolic processes, and inflammatory cytokines, such as TNF-α, have been found elevated in muscle atrophy and implicated in its pathogenesis. GHRH, in addition to stimulating GH secretion from the pituitary, exerts survival and antiapoptotic effects in different cell types. Moreover, we and others have recently shown that GHRH displays antiapoptotic effects in isolated cardiac myocytes and protects the isolated heart from ischemia/reperfusion injury and myocardial infarction in vivo. On these bases, we investigated the effects of GHRH on survival and apoptosis of TNF-α-treated C2C12 myotubes along with the underlying mechanisms. GHRH increased myotube survival and prevented TNF-α-induced apoptosis through GHRH receptor-mediated mechanisms. These effects involved activation of phosphoinositide 3-kinase/Akt pathway and inactivation of glycogen synthase kinase-3β, whereas mammalian target of rapamycin was unaffected. GHRH also increased the expression of myosin heavy chain and the myogenic transcription factor myogenin, which were both reduced by the cytokine. Furthermore, GHRH inhibited TNF-α-induced expression of nuclear factor-κB, calpain, and muscle ring finger1, which are all involved in muscle protein degradation. In summary, these results indicate that GHRH exerts survival and antiapoptotic effects in skeletal muscle cells through the activation of anabolic pathways and the inhibition of proteolytic routes. Overall, our findings suggest a novel therapeutic role for GHRH in the treatment of muscle atrophy-associated diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Cell Differentiation
  • Cell Line
  • Cell Survival
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • Growth Hormone-Releasing Hormone / physiology*
  • Mice
  • Muscle Fibers, Skeletal / cytology
  • Muscle Fibers, Skeletal / physiology*
  • Muscle Proteins / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Proteolysis
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Neuropeptide / metabolism
  • Receptors, Pituitary Hormone-Regulating Hormone / metabolism
  • Signal Transduction
  • TOR Serine-Threonine Kinases / metabolism
  • Tumor Necrosis Factor-alpha

Substances

  • Muscle Proteins
  • Receptors, Neuropeptide
  • Receptors, Pituitary Hormone-Regulating Hormone
  • Tumor Necrosis Factor-alpha
  • Growth Hormone-Releasing Hormone
  • mTOR protein, mouse
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, mouse
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Glycogen Synthase Kinase 3
  • somatotropin releasing hormone receptor