Protein Kinase C Activity Is Required for Aryl Hydrocarbon Receptor Pathway-Mediated Signal Transduction
- 1Graduate Program in Biochemistry Cell and Molecular Biology (W.P.L.) and 2Center for Molecular Toxicology (M.P.-G., J.C.T., G.H.P.), Department of Veterinary Science, The Pennsylvania State University, University Park, Pennsylvania 16802
Abstract
The role of protein kinase C (PKC) in the human aryl hydrocarbon receptor (hAhR) signal transduction pathway was examined in cell lines stably transfected with pGUDLUC6.1, in which luc+ is solely controlled by four dioxin-responsive elements (DREs). These cell lines, P5A11 and HG40/6, were derived from HeLa and HepG2 cells respectively. Simultaneous treatment of these cells with 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD) and phorbol-12-myristate-13-acetate (PMA) enhancedtrans-activation of the reporter construct several-fold relative to cells treated with TCDD alone. PKC inhibitors block the PMA effect and hAhR-mediated signal transduction, demonstrating these processes require PKC activity. Examination of other independently generated, HeLa-derived cell lines stably transfected with pGUDLUC6.1 demonstrates the PMA effect in P5A11 cells is not a clonal artifact. Transient transfections indicate the PMA effect is not due to a luciferase message/gene product stabilization mechanism or stimulation of the basal transcription machinery. Examination of cytosolic preparations demonstrates PKC stimulation or inhibition does not alter hAhR and hAhR nuclear translocator protein levels or TCDD-induced down-regulation of hAhR levels. Similarly, examination of nuclear extracts indicated PKC stimulation or inhibition does not alter nuclear AhR levels or hAhR/hAhR nuclear translocator protein heterodimer DRE-binding activity as assessed by electrophoretic mobility shift assay. These results demonstrate a PKC-mediated event is required for the hAhR to form a functional transcriptional complex that leads totrans-activation and that the DRE is the minimal DNA element required for PMA to enhance AhR-mediatedtrans-activation.
Footnotes
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Send reprint requests to: Dr. Gary H. Perdew, Department of Veterinary Science, The Pennsylvania State University, 115 Henning Building, University Park, PA 16802. E-mail: ghp2{at}psu.edu
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This work was supported by National Institute of Environmental Health Science Grant ES04869.
- Abbreviations:
- PKC
- protein kinase C
- hAhR
- human aryl hydrocarbon receptor
- DRE
- dioxin-responsive element
- TCDD
- 2,3,7,8,-tetrachlorodibenzo-p-dioxin
- PMA
- phorbol-12-myristate-13-acetate
- hARNT
- human aryl hydrocarbon receptor nuclear translocator protein
- HSP90
- 90-kDa heat shock protein
- HEPES
- 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- EMSA
- electrophoretic mobility shift assay
- PAS
- PER/ARNT/SIM (periodicity/aryl hydrocarbon receptor nuclear translocator protein/simple-minded)
- DAG
- sn-1,2-diacylglycerol
- βNF
- β- naphthoflavone
- 8-bromo-cAMP
- 8-bromoadenosine-cAMP
- Bis I
- bisindolylmaleimide I·HCl
- Chel
- chelerythrine chloride
- FBS
- fetal bovine serum
- PBS
- phosphate-buffered saline
- α-MEM
- α-minimum essential media
- mAb
- monoclonal antibody
- 4-O-methyl-PMA
- 4-O-methyl-phorbol-12-myristate-13-acetate
- PKA
- protein kinase A
- TRE
- 12-O-tetradecanoylphorbol-13-acetate-responsive element
- BSA
- bovine serum albumin
- DMSO
- dimethylsulfoxide
- MOPS
- 3-(N-morpholino)propanesulfonic acid
- CHAPS
- 3-[(3-cholamidopropyl)dimethylammonio]propanesulfonate
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- Received September 26, 1997.
- Accepted January 6, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
