Platelet-activating factor (PAF) positively auto-regulates the expression of human PAF receptor transcript 1 (leukocyte-type) through NF-kappa B.
The human platelet-activating factor receptor (PAFR) gene is transcribed by two distinct promoters (promoter 1 and promoter 2) to generate two transcripts (designated as PAFR transcript 1 and PAFR transcript 2), though their open reading frames are identical. By primer extension analysis to discriminate two transcripts, we found that the levels of PAFR transcript 1 (leukocyte-type), but not PAFR transcript 2 (tissue-type), are upregulated by PAF as well as by 12-O-tetradecanoylphorbol-13-acetate (TPA) in the human stomach cancer cell line (JR-St cells) which expresses both functional PAFR transcript 1 and PAFR transcript 2 endogenously. Functional analysis of the promoter 1 with a transient expression assay using chloramphenicol acetyltransferase (CAT) gene as a reporter showed that both PAF and TPA activated the promoter 1 but not the deleted promoter lacking the three consensus binding sites for NF-kappa B located from -571 bp to -459 bp. These findings suggest a molecular mechanism of positive regulation of PAFR gene expression by PAF through NF-kappa B, possibly by a phosphorylation reaction involving protein kinase C by PAF.
Mutoh
H
H
Department of Biochemistry, Faculty of Medicine, University of Tokyo, Japan.
Ishii
S
S
Izumi
T
T
Kato
S
S
Shimizu
T
T
D001483:Base Sequence; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D017931:DNA Primers; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007962:Leukocytes; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D016366:Open Reading Frames; D010972:Platelet Activating Factor / Q000494:pharmacology*; D010980:Platelet Membrane Glycoproteins / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D013274:Stomach Neoplasms; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D017931:DNA Primers; D016328:NF-kappa B; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D015500:Chloramphenicol O-Acetyltransferase; D013755:Tetradecanoylphorbol Acetate