SDF-1alpha up-regulates interleukin-6 through CXCR4, PI3K/Akt, ERK, and NF-kappaB-dependent pathway in microglia

Eur J Pharmacol. 2009 Jun 24;613(1-3):146-54. doi: 10.1016/j.ejphar.2009.03.001. Epub 2009 Mar 11.

Abstract

Stromal cell-derived factor-1 (SDF-1), also known as CXCL12, and its receptor CXC chemokine receptor 4 (CXCR4) express in various kinds of cells in central nervous system. The SDF-1/CXCR4 signaling pathway is regulated by diverse biological effects. SDF-1 is up-regulated in the ischemic penumbra following stroke and has been known to be associated with the homing of bone marrow cells to injury. However, the effect of SDF-1alpha/CXCR4 on cytokine production in microglia is mostly unknown. Here, we demonstrated that SDF-1alpha enhanced IL-6 production in both primary cultured microglia and BV-2 microglia. We further investigated the signaling pathway involved in IL-6 production stimulated by SDF-1alpha in microglia. SDF-1alpha increased IL-6 production in both protein and mRNA levels. These effects were attenuated by ERK, phosphatidylinositol 3-kinase (PI3K), NF-kappaB inhibitors, and IkappaB protease inhibitor. Stimulation of microglia with SDF-1alpha also increased Akt and ERK1/2 phosphorylation. In addition, SDF-1alpha treatment also increased IkappaB kinase alpha/beta (IKK alpha/beta) phosphorylation, IkappaBalpha phosphorylation, IkappaBalpha degradation, p65 phosphorylation at Ser(276), translocation of p65 and p50 from cytosol to nucleus and kappaB-luciferase activity. Moreover, SDF-1alpha-mediated increase of kappaB-luciferase activity was inhibited by pre-transfection of DN-p85, DN-Akt or DN-ERK2. Increase of IKK alpha/beta phosphorylation and binding of p65 and p50 to the NF-kappaB element were both antagonized by PI3K and ERK inhibitors. Our results demonstrate a mechanism linking SDF-1alpha and IL-6, and provide additional support for the notion that SDF-1alpha plays a regulatory role in microglia activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Chemokine CXCL12 / metabolism
  • Chemokine CXCL12 / pharmacology*
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Humans
  • I-kappa B Kinase / metabolism
  • Interleukin-6 / biosynthesis
  • Interleukin-6 / genetics*
  • Intracellular Space / drug effects
  • Intracellular Space / metabolism
  • Mice
  • Microglia / cytology
  • Microglia / drug effects*
  • Microglia / metabolism*
  • NF-kappa B / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats
  • Receptors, CXCR4 / metabolism
  • Signal Transduction / drug effects*
  • Up-Regulation / drug effects*

Substances

  • Chemokine CXCL12
  • Interleukin-6
  • NF-kappa B
  • Receptors, CXCR4
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-akt
  • I-kappa B Kinase
  • Extracellular Signal-Regulated MAP Kinases