We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Reduced activation of phosphatidylinositol-3 kinase and increased serine 636 phosphorylation of insulin receptor substrate-1 in primary culture of skeletal muscle cells from patients with type 2 diabetes.
- Authors
Bouzakri, Karim; Roques, Marina; Gual, Philippe; Espinosa, Sophie; Guebre-Egziabher, Fitsum; Riou, Jean-Paul; Laville, Martine; Le Marchand-Brustel, Yannick; Tanti, Jean-François; Vidal, Hubert
- Abstract
To understand better the defects in the proximal steps of insulin signaling during type 2 diabetes, we used differentiated human skeletal muscle cells in primary culture. When compared with cells from control subjects, myotubes established from patients with type 2 diabetes presented the same defects as those previously evidenced in vivo in muscle biopsies, including defective stimulation of phosphatidylinositol (PI) 3-kinase activity, decreased association of PI 3-kinase with insulin receptor substrate (IRS)-1 and reduced IRS-1 tyrosine phosphorylation during insulin stimulation. In contrast to IRS-1, the signaling through IRS-2 was not altered. Investigating the causes of the reduced tyrosine phosphorylation of IRS-1, we found a more than twofold increase in the basal phosphorylation of IRS-1 on serine 636 in myotubes from patients with diabetes. Concomitantly, there was a higher basal mitogen-activated protein kinase (MAPK) activity in these cells, and inhibition of the MAPKs with PD98059 strongly reduced the level of serine 636 phosphorylation. These results suggest that IRS-1 phosphorylation on serine 636 might be involved in the reduced phosphorylation of IRS-1 on tyrosine and in the subsequent alteration of insulin-induced PI 3-kinase activation. Moreover, increased MAPK activity seems to play a role in the phosphorylation of IRS-1 on serine residue in human muscle cells.
- Publication
Diabetes, 2003, Vol 52, Issue 6, p1319
- ISSN
0012-1797
- Publication type
Journal Article
- DOI
10.2337/diabetes.52.6.1319