Biological activity of truncated C-terminus human heat shock protein 72

Derek S. Wheeler, Katherine E. Dunsmore, Alvin G. Denenberg, Larissa Muething, Sue E. Poynter, Hector R. Wong*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Heat shock protein 72 (Hsp72), a canonical intracellular molecular chaperone, may also function as an extracellular danger signal for the innate immune system. To further delineate the biological role of Hsp72 in the innate immune system, we generated two truncated versions of the full length human Hsp72 (N-terminus Hsp72, amino acids 1-430; and C-terminus Hsp72 amino acids 420-641) and directly compared their ability to activate cells from the macrophage/monocyte lineage. In RAW 264.7 macrophages transfected with a NF-κB-dependent luciferase reporter plasmid, C-terminus Hsp72 was a more potent inducer of NF-κB activity than N-terminus Hsp72, and this effect did not seem to be secondary to endotoxin contamination. C-terminus Hsp72-mediated activation of the NF-κB pathway was corroborated by increased activation of IκB kinase, degradation of IκBα, and increased NF-κB-DNA binding. C-terminus Hsp72 was a more potent inducer of tumor necrosis factor-α (TNFα) expression in RAW 264.7 macrophages and in primary murine peritoneal macrophages from wild-type mice. C-terminus Hsp72 did not induce TNFα expression in primary murine peritoneal macrophages from Toll-like receptor (TLR4) mutant mice, indicating a role for TLR4. In human THP-1 mononuclear cells, C-terminus Hsp72 induced tolerance to subsequent LPS stimulation, whereas N-terminus Hsp72 did not induce tolerance. Finally, control experiments using equimolar amounts of N-terminus or C-terminus Hsp72 demonstrated a higher biological potency for C-terminus Hsp72. These data demonstrate that the ability of human Hsp72 to serve as an activator for cells of the macrophage/monocyte lineage primarily lies in the C-terminus region spanning amino acids 420-641.

Original languageEnglish (US)
Pages (from-to)173-179
Number of pages7
JournalImmunology Letters
Volume135
Issue number1-2
DOIs
StatePublished - Mar 30 2011
Externally publishedYes

Keywords

  • Danger signal
  • Heat shock protein
  • Inflammation

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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