High-fat feeding effects on components of the CAP/Cbl signaling cascade in Sprague-Dawley rat skeletal muscle

Metabolism. 2006 Feb;55(2):203-12. doi: 10.1016/j.metabol.2005.08.013.

Abstract

The aim of this investigation was to determine whether the CAP (Cbl-associated protein)/Cbl signaling cascade is present and responsive to insulin in skeletal muscle and if high-fat feeding impairs insulin-stimulated activation of this signaling cascade. Sprague-Dawley rats were assigned to either control (n = 16) or high fat-fed (n = 16) dietary groups. After a 12-week dietary period, animals were subjected to hind limb perfusions in the presence (n = 8 per group) or absence (n = 8 per group) of insulin. High-fat feeding reduced rates of insulin-stimulated skeletal muscle phosphatidylinositol 3-kinase activity and 3-O-methylglucose transport. In plasma membrane fractions, neither the high-fat diet nor insulin altered the insulin receptor beta subunit (IR-beta), APS (adaptor protein containing PH and SH2 domains), c-Cbl, or TC10 protein concentration, but high-fat feeding did decrease CAP protein concentration. APS, c-Cbl, CAP, and TC10 messenger RNA were present in the skeletal muscle and reflected the protein concentration of experimental groups. Despite insulin-stimulated plasma membrane IR-beta tyrosine phosphorylation being unaffected by high-fat feeding, c-Cbl tyrosine phosphorylation, the kinase activity of IR-beta toward APS, and glucose transporter 4 protein concentration were all significantly reduced in insulin-stimulated plasma membrane prepared from the skeletal muscle of high fat-fed animals. These findings suggest that the CAP/Cbl signaling cascade is present in skeletal muscle, activated by insulin, and impaired by high-fat feeding.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / physiology*
  • Dietary Fats / administration & dosage*
  • Dietary Fats / metabolism
  • Glucose Transporter Type 4 / physiology
  • Insulin / physiology
  • Insulin Receptor Substrate Proteins
  • Male
  • Phosphatidylinositol 3-Kinases / physiology
  • Phosphoproteins / physiology
  • Proto-Oncogene Proteins c-cbl / genetics
  • Proto-Oncogene Proteins c-cbl / physiology*
  • Quadriceps Muscle / physiology*
  • RNA / genetics
  • Rats
  • Rats, Sprague-Dawley
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / physiology*
  • rho GTP-Binding Proteins / genetics
  • rho GTP-Binding Proteins / physiology

Substances

  • Cytoskeletal Proteins
  • Dietary Fats
  • Glucose Transporter Type 4
  • Insulin
  • Insulin Receptor Substrate Proteins
  • Irs1 protein, rat
  • Phosphoproteins
  • RNA
  • Proto-Oncogene Proteins c-cbl
  • Phosphatidylinositol 3-Kinases
  • RHOQ protein, human
  • rho GTP-Binding Proteins