Regulation of Skeletal Muscle DRP-1 and FIS-1 Protein Expression by IL-6 Signaling

Oxid Med Cell Longev. 2019 Feb 21:2019:8908457. doi: 10.1155/2019/8908457. eCollection 2019.

Abstract

IL-6 signals through the ubiquitously expressed glycoprotein 130 (gp130) transmembrane protein to activate intracellular signaling that includes signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase 1/2 (ERK1/2). Dynamin-1-like protein (DRP-1) and mitochondrial fission 1 protein (FIS-1) are key proteins in the process of mitochondrial fission and have emerged as IL-6-sensitive targets. The purpose of this study was to examine the regulation of DRP-1 and FIS-1 expression by IL-6 and gp130 signaling in myotubes and skeletal muscle. Fully differentiated C2C12 myotubes were treated with 100 ng of IL-6 for 24 hours in the presence of gp130siRNA, C188-9 (STAT3 inhibitor), or PD98059 (ERK1/2 inhibitor). Male C57BL/6 (B6) and muscle-specific gp130 knockout mice (KO) had IL-6 systemically overexpressed for 2 weeks by transient transfection with 50 ng of an IL-6-expressing or control plasmid in the quadriceps muscles, and the tibialis anterior muscle was analyzed to determine systemic effects of IL-6. IL-6 induced DRP-1 and FIS-1 expression in myotubes 124% and 82% (p = .001) and in skeletal muscle 97% and 187% (p = .001). Myotube gp130 knockdown suppressed the IL-6 induction of DRP-1 68% (p = .002) and FIS-1 65% (p = .001). Muscle KO suppressed the IL-6 induction of DRP-1 220% (p = .001) and FIS-1 121% (p = .001). ERK1/2 inhibition suppressed the IL-6 induction of DRP-1 59% (p = .0003) and FIS-1 102% (p = .0001) in myotubes, while there was no effect of STAT3 inhibition. We report that chronically elevated IL-6 can directly induce DRP-1 and FIS-1 expression through gp130 signaling in cultured myotubes and skeletal muscle. Furthermore, ERK 1/2 signaling is necessary for the IL-6 induction of DRP-1 and FIS-1 expression in myotubes.

MeSH terms

  • Animals
  • Cell Line
  • Cytokine Receptor gp130 / metabolism
  • Dynamins / metabolism*
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Inflammation / pathology
  • Interleukin-6 / metabolism*
  • Male
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitochondrial Dynamics / drug effects
  • Mitochondrial Proteins / metabolism*
  • Muscle Fibers, Skeletal / metabolism
  • Muscle, Skeletal / metabolism*
  • STAT3 Transcription Factor / metabolism
  • Signal Transduction*

Substances

  • FIS1 protein, mouse
  • Interleukin-6
  • Mitochondrial Proteins
  • STAT3 Transcription Factor
  • Cytokine Receptor gp130
  • Extracellular Signal-Regulated MAP Kinases
  • Dnm1l protein, mouse
  • Dynamins