Adenosine-induced expression of interleukin-6 in astrocytes through protein kinase A and NF-IL-6

Glia. 2000 Jul;31(1):51-8. doi: 10.1002/(sici)1098-1136(200007)31:1<51::aid-glia50>3.0.co;2-m.

Abstract

In various neurologic diseases, astrocytes express interleukin-6 (IL-6), which is an endogenous pyrogen, a neuroprotective factor, and a regulator of the blood-brain barrier. The expression of IL-6 in astrocytes is stimulated by extracellular adenosine through A(2B) receptors. To investigate the signaling cascade that induces IL-6 gene transcription further, we transfected primary mouse astrocytes with a reporter gene construct, in which luciferase expression is directed by the human IL-6 promoter. Expression of PKI, an inhibitor of protein kinase A (PKA), interfered with IL-6 transcription indicating that PKA mediates the effect of adenosine. The CAAT box of the IL-6 promoter is necessary for the stimulation by adenosine as a mutation in this element reduced the stimulation by adenosine. Indeed, the cAMP agonist forskolin increased the binding of the transcription factors NF-IL-6 and C/EBPdelta to the CAAT box of the IL-6 promoter in nuclear extracts of astrocytes. Inhibition of the de novo synthesis of NF-IL-6 by cycloheximide or an antisense oligonucleotide reduced the enhancement of NF-IL-6 binding to the CAAT box and inhibited stimulation of IL-6 transcription by forskolin. In addition, overexpression of NF-IL-6 induced IL-6 transcription. This suggests that adenosine induces the de novo synthesis of NF-IL-6 through activation of PKA and thereby stimulates transcription of IL-6 in astrocytes.

MeSH terms

  • Adenosine / pharmacology*
  • Animals
  • Astrocytes / metabolism
  • Astrocytes / physiology*
  • Base Sequence / genetics
  • CCAAT-Enhancer-Binding Proteins
  • Cells, Cultured
  • Colforsin / pharmacology
  • Cyclic AMP / agonists
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • DNA-Binding Proteins / antagonists & inhibitors
  • DNA-Binding Proteins / metabolism*
  • DNA-Binding Proteins / physiology
  • Gene Expression / drug effects*
  • Humans
  • Interleukin-6 / genetics*
  • Mice
  • Nuclear Proteins / antagonists & inhibitors
  • Nuclear Proteins / metabolism*
  • Nuclear Proteins / physiology
  • Oligonucleotides, Antisense / pharmacology
  • Promoter Regions, Genetic / genetics
  • Promoter Regions, Genetic / physiology
  • Tissue Distribution
  • Transcription, Genetic / drug effects
  • Transcription, Genetic / physiology
  • Transcriptional Activation / physiology
  • Transfection

Substances

  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • Interleukin-6
  • Nuclear Proteins
  • Oligonucleotides, Antisense
  • Colforsin
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Adenosine