Bimodal effect on pancreatic β-cells of secretory products from normal or insulin-resistant human skeletal muscle

Diabetes. 2011 Apr;60(4):1111-21. doi: 10.2337/db10-1178. Epub 2011 Mar 4.

Abstract

Objective: Type 2 diabetes is characterized by insulin resistance with a relative deficiency in insulin secretion. This study explored the potential communication between insulin-resistant human skeletal muscle and primary (human and rat) β-cells.

Research design and methods: Human skeletal muscle cells were cultured for up to 24 h with tumor necrosis factor (TNF)-α to induce insulin resistance, and mRNA expression for cytokines was analyzed and compared with controls (without TNF-α). Conditioned media were collected and candidate cytokines were measured by antibody array. Human and rat primary β-cells were used to explore the impact of exposure to conditioned media for 24 h on apoptosis, proliferation, short-term insulin secretion, and key signaling protein phosphorylation and expression.

Results: Human myotubes express and release a different panel of myokines depending on their insulin sensitivity, with each panel exerting differential effects on β-cells. Conditioned medium from control myotubes increased proliferation and glucose-stimulated insulin secretion (GSIS) from primary β-cells, whereas conditioned medium from TNF-α-treated insulin-resistant myotubes (TMs) exerted detrimental effects that were either independent (increased apoptosis and decreased proliferation) or dependent on the presence of TNF-α in TM (blunted GSIS). Knockdown of β-cell mitogen-activated protein 4 kinase 4 prevented these effects. Glucagon-like peptide 1 protected β-cells against decreased proliferation and apoptosis evoked by TMs, while interleukin-1 receptor antagonist only prevented the latter.

Conclusions: Taken together, these data suggest a possible new route of communication between skeletal muscle and β-cells that is modulated by insulin resistance and could contribute to normal β-cell functional mass in healthy subjects, as well as the decrease seen in type 2 diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Culture Media, Conditioned / metabolism
  • Culture Media, Conditioned / pharmacology*
  • Cytokines / metabolism
  • Humans
  • In Situ Nick-End Labeling
  • Insulin / metabolism
  • Insulin Receptor Substrate Proteins / genetics
  • Insulin Resistance / physiology*
  • Insulin Secretion
  • Insulin-Secreting Cells / drug effects*
  • Insulin-Secreting Cells / metabolism*
  • Male
  • Muscle Fibers, Skeletal / metabolism*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • RNA Interference
  • Rats
  • Rats, Wistar
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Culture Media, Conditioned
  • Cytokines
  • Insulin
  • Insulin Receptor Substrate Proteins
  • Irs1 protein, rat
  • Tumor Necrosis Factor-alpha
  • Protein-Serine-Threonine Kinases