Contraction regulates site-specific phosphorylation of TBC1D1 in skeletal muscle

Biochem J. 2010 Oct 15;431(2):311-20. doi: 10.1042/BJ20101100.

Abstract

TBC1D1 (tre-2/USP6, BUB2, cdc16 domain family member 1) is a Rab-GAP (GTPase-activating protein) that is highly expressed in skeletal muscle, but little is known about TBC1D1 regulation and function. We studied TBC1D1 phosphorylation on three predicted AMPK (AMP-activated protein kinase) phosphorylation sites (Ser231, Ser660 and Ser700) and one predicted Akt phosphorylation site (Thr590) in control mice, AMPKα2 inactive transgenic mice (AMPKα2i TG) and Akt2-knockout mice (Akt2 KO). Muscle contraction significantly increased TBC1D1 phosphorylation on Ser231 and Ser660, tended to increase Ser700 phosphorylation, but had no effect on Thr590. AICAR (5-aminoimidazole-4-carboxyamide ribonucleoside) also increased phosphorylation on Ser231, Ser660 and Ser700, but not Thr590, whereas insulin only increased Thr590 phosphorylation. Basal and contraction-stimulated TBC1D1 Ser231, Ser660 and Ser700 phosphorylation were greatly reduced in AMPKα2i TG mice, although contraction still elicited a small increase in phosphorylation. Akt2 KO mice had blunted insulin-stimulated TBC1D1 Thr590 phosphorylation. Contraction-stimulated TBC1D1 Ser231 and Ser660 phosphorylation were normal in high-fat-fed mice. Glucose uptake in vivo was significantly decreased in tibialis anterior muscles overexpressing TBC1D1 mutated on four predicted AMPK phosphorylation sites. In conclusion, contraction causes site-specific phosphorylation of TBC1D1 in skeletal muscle, and TBC1D1 phosphorylation on AMPK sites regulates contraction-stimulated glucose uptake. AMPK and Akt regulate TBC1D1 phosphorylation, but there must be additional upstream kinases that mediate TBC1D1 phosphorylation in skeletal muscle.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Aminoimidazole Carboxamide / analogs & derivatives
  • Aminoimidazole Carboxamide / pharmacology
  • Animals
  • Antibodies, Phospho-Specific / pharmacology
  • Consensus Sequence
  • Dietary Fats / pharmacology
  • GTPase-Activating Proteins
  • Glucose / metabolism
  • In Vitro Techniques
  • Insulin / pharmacology
  • Mice
  • Muscle Contraction / drug effects
  • Muscle Contraction / physiology*
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / enzymology
  • Muscle, Skeletal / physiology*
  • Mutant Proteins / metabolism
  • Mutation / genetics
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phosphorylation / drug effects
  • Phosphoserine / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Ribonucleotides / pharmacology

Substances

  • Antibodies, Phospho-Specific
  • Dietary Fats
  • GTPase-Activating Proteins
  • Insulin
  • Mutant Proteins
  • Nuclear Proteins
  • Ribonucleotides
  • Tbc1d1 protein, mouse
  • Phosphoserine
  • Aminoimidazole Carboxamide
  • Proto-Oncogene Proteins c-akt
  • AMP-Activated Protein Kinases
  • AICA ribonucleotide
  • Glucose