The regulation of GRP78 and messenger RNA levels by hypoxia is modulated by protein kinase C activators and inhibitors

Radiat Res. 1994 Apr;138(1 Suppl):S60-3.

Abstract

In this study, we have shown that steady-state levels of glucose-regulated 78 kDa (GRP78) protein and messenger RNA increase during a 5-h exposure to 0.02% oxygen. This increase in GRP78 protein and mRNA induced by hypoxia can be abolished by a 1-h pretreatment of cells before hypoxia with the protein kinase C (PKC) inhibitors staurosporine and H7 at concentrations at which the drugs themselves do not cause cytotoxicity. Although all studies using protein kinase inhibitors must be interpreted with caution, staurosporine and H7 have been shown to be potent inhibitors of PKC activity, suggesting a role for PKC in mediating the transcriptional regulation of GRP78 by hypoxia. Further support for PKC in regulating GRP78 gene expression by hypoxia stems from gel-mobility shift studies in mixtures of nuclear extracts from aerobic or hypoxic cells with a 36 bp region of the GRP78 promoter (-170 to -135). Binding of this factor could be inhibited by pretreating cells with the PKC inhibitor staurosporine before hypoxia or activated by treating cells with the PKC-activating phorbol ester TPA. These data suggest that activation of this hypoxia-responsive factor is sensitive to oxygen levels and seems to be mediated through a PKC signal transduction pathway.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
  • Alkaloids / pharmacology
  • Base Sequence
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Cell Hypoxia
  • Cells, Cultured
  • Enzyme Activation
  • Gene Expression Regulation
  • Heat-Shock Proteins / genetics*
  • Heat-Shock Proteins / metabolism
  • Humans
  • Isoquinolines / pharmacology
  • Molecular Chaperones*
  • Molecular Sequence Data
  • Oligodeoxyribonucleotides
  • Oxygen / metabolism*
  • Piperazines / pharmacology
  • Promoter Regions, Genetic
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / drug effects
  • Protein Kinase C / metabolism*
  • RNA, Messenger / metabolism*
  • Signal Transduction
  • Staurosporine
  • Tetradecanoylphorbol Acetate / pharmacology
  • Tumor Cells, Cultured

Substances

  • Alkaloids
  • Carrier Proteins
  • Heat-Shock Proteins
  • Isoquinolines
  • Molecular Chaperones
  • Oligodeoxyribonucleotides
  • Piperazines
  • RNA, Messenger
  • 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
  • Protein Kinase C
  • Staurosporine
  • Tetradecanoylphorbol Acetate
  • Oxygen
  • molecular chaperone GRP78