A 78-kDa glucose-regulated protein is involved in the decrease of interleukin-6 secretion by lead treatment from astrocytes

Am J Physiol Cell Physiol. 2007 Sep;293(3):C897-905. doi: 10.1152/ajpcell.00059.2007. Epub 2007 Jun 13.


Interleukin (IL)-6 is a cytokine produced mainly by microglia and astrocytes and plays a pleiotropic role in the central nervous system. In this study, we cloned rat IL-6 cDNA into an enhanced green fluorescent protein (EGFP) or a red fluorescent protein (DsRed2) vector and rat 78-kDa glucose-regulated protein (GRP78) cDNA into an EGFP vector to construct IL-6-EGFP, IL-6-DsRed2, and GRP78-EGFP chimeras for the investigation of the mechanism of IL-6 secretion from astrocytes. The data showed that constructed IL-6-EGFP and IL-6-DsRed2 chimeras retained the secretory property, and the secretion of IL-6-EGFP from astrocytes could be attenuated by GRP78 depletion with double-stranded RNA interference. Coexpression of IL-6-DsRed2 and dysfunctional GRP78-EGFP abolished IL-6-DsRed2 secretion, and two chimeric proteins colocalized inside living astrocytes. Coimmunoprecipitation analysis indicated that IL-6 and GRP78 resided in the same complex. The data further revealed that IL-6-EGFP secretion from astrocytes was blocked by the heavy metal lead (Pb) in a concentration-dependent manner. Analysis of the Pb interaction with protein on a Pb-affinity column demonstrated that Pb bound to GRP78 but failed to bind to IL-6. Therefore, these data suggest that IL-6-EGFP or IL-6-DsRed2 chimeras can be used as imaging probes to study IL-6 secretion from living cells, that GRP78 is involved in IL-6 secretion from astrocytes, and that Pb can block IL-6 secretion from astrocytes via targeting GRP78.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / cytology
  • Astrocytes / drug effects*
  • Astrocytes / metabolism*
  • Cells, Cultured
  • Green Fluorescent Proteins / genetics
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism*
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism*
  • Lead / toxicity*
  • Luminescent Proteins / genetics
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism*
  • Neurotoxins / toxicity
  • Rats
  • Rats, Sprague-Dawley
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Transfection


  • GRP78 protein, rat
  • Heat-Shock Proteins
  • Interleukin-6
  • Luminescent Proteins
  • Molecular Chaperones
  • Neurotoxins
  • Recombinant Fusion Proteins
  • fluorescent protein 583
  • Green Fluorescent Proteins
  • Lead