Insulin-like growth factor binding protein-1 activates integrin-mediated intracellular signaling and migration in oligodendrocytes

J Neurochem. 2010 Jun;113(5):1319-30. doi: 10.1111/j.1471-4159.2010.06703.x. Epub 2010 Mar 25.

Abstract

In multiple sclerosis (MS), oligodendrocytes in lesions are lost, leaving damaged tissue virtually devoid of these myelin-producing cells. Our group has recently demonstrated enhanced expression of insulin-like growth factor (IGF) binding protein-1 (IGFBP-1) in oligodendrocytes (CNPase(+)) localized adjacent to MS lesions. In the present study, we demonstrate IGF-1-independent actions of IGFBP-1 on OLN-93 oligodendroglial cells, including activation of kinases ERK1/2, focal adhesion kinase and p21-activated kinase as well as small monomeric GTPases Rac and Ral. Activation of these intracellular signaling components was inhibited by GRGDS peptide, indicating signaling through integrin receptors. While both IGF-1 and IGFBP-1 demonstrated rapid induction of actin polymerization, IGFBP-1 proved to be a more potent inducer of migration than IGF-1, inducing a threefold increased migration rate. Furthermore, through integrin receptor signaling IGFBP-1 induced rapid transient translocalization of intracellular Rac toward punctuated structures followed by translocation of Rac to the plasma membrane. Our results suggest that up-regulation of IGFBP-1 in oligodendrocytes in MS may serve two functions: (i) regulate IGF-1 actions, (ii) exert IGF-independent effects through its RGD sequence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Animals
  • Astrocytes / drug effects
  • Astrocytes / physiology
  • Blotting, Western
  • Cell Movement / drug effects*
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Enzyme Activation / drug effects
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Extracellular Signal-Regulated MAP Kinases / physiology
  • Fluorescent Antibody Technique
  • Focal Adhesion Kinase 1 / metabolism
  • Insulin-Like Growth Factor Binding Protein 1 / pharmacology*
  • Insulin-Like Growth Factor I / metabolism
  • Integrins / physiology*
  • Oligodendroglia / drug effects*
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / drug effects*
  • p21-Activated Kinases / metabolism
  • rac GTP-Binding Proteins / metabolism
  • ral GTP-Binding Proteins / metabolism

Substances

  • Actins
  • Insulin-Like Growth Factor Binding Protein 1
  • Integrins
  • Insulin-Like Growth Factor I
  • Focal Adhesion Kinase 1
  • p21-Activated Kinases
  • Extracellular Signal-Regulated MAP Kinases
  • rac GTP-Binding Proteins
  • ral GTP-Binding Proteins