Integrin-linked kinase is a positive mediator of L6 myoblast differentiation

Biochem Biophys Res Commun. 2003 Oct 24;310(3):796-803. doi: 10.1016/j.bbrc.2003.09.080.

Abstract

Overexpression of ILK in L6 myoblasts results in increased ILK kinase activity, stimulating myotube formation and induction of biochemical differentiation markers. Expression of a dominant negative ILK mutant, ILK(E359K), inhibits endogenous ILK activation and L6 differentiation. Cell cycle analysis of ILK(E359K) cells cultured in serum-free conditions indicates significant apoptosis (11-19% sub-diploid peak) which is not seen in insulin treated cells. Expression of ILK variants does not have significant effects on S-phase transit, however. Known targets of ILK, PKB/Akt or glycogen synthase kinase 3beta are not obviously involved in ILK-induced L6 differentiation. Insulin-stimulated phosphorylation of PKB at Ser473 is unimpaired in the ILK(E359K) cells, suggesting that PKB is not a myogenic target of ILK. Inhibition of GSK3beta by LiCl blocks L6 myogenesis, indicating that ILK-mediated inhibition of GSK3beta is not sufficient for differentiation. Our data do suggest that a LiCl-sensitive interaction of ILK is important in L6 myoblast differentiation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Apoptosis
  • Blotting, Western
  • Calcium-Transporting ATPases / metabolism
  • Cell Cycle
  • Cell Differentiation
  • Cell Line
  • Cell Nucleus / metabolism
  • Cell Separation
  • Cells, Cultured
  • Culture Media, Serum-Free / pharmacology
  • DNA, Complementary / metabolism
  • Enzyme Inhibitors / pharmacology
  • Epitopes
  • Flow Cytometry
  • Genes, Dominant
  • Genetic Vectors
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • Insulin / pharmacology
  • Lithium Chloride / pharmacology
  • Mutation
  • Myocardium / cytology*
  • Phosphatidylinositol 3-Kinases / metabolism
  • Protein-Serine-Threonine Kinases / physiology*
  • Rats
  • Time Factors
  • Transfection

Substances

  • Culture Media, Serum-Free
  • DNA, Complementary
  • Enzyme Inhibitors
  • Epitopes
  • Insulin
  • integrin-linked kinase
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, rat
  • Protein-Serine-Threonine Kinases
  • Glycogen Synthase Kinase 3
  • Calcium-Transporting ATPases
  • Lithium Chloride