Expression and function of the nuclear factor of activated T cells in colon carcinoma cells: involvement in the regulation of cyclooxygenase-2.
Increasing evidence shows a crucial role of the Ca2+/ calcineurin-mediated activation of the nuclear factor of activated T cells (NFAT) in the regulation of a variety of processes in nonimmune cells. Here we provide evidence that NFATc1 and NFATc2 are expressed in human colon carcinoma cell lines. These proteins are translocated from the cytoplasm to the nucleus upon treatment with a combination of phorbol 12-myristate 13-acetate plus the calcium ionophore A23187. Subsequent to translocation to the nucleus, NFATc1 and NFATc2 were able to bind to a NFAT response element in the DNA, regulating transcriptional activation of genes containing a NFAT-responsive element such as cyclooxygenase-2 (COX-2). COX-2 expression and prostaglandin E2 (PGE2) production were induced upon pharmacological stimuli leading to NFAT activation and blunted by inhibition of calcineurin phosphatase with cyclosporin A or tacrolimus (FK506). Expression of NFAT wild type protein or the active catalytic subunit of calcineurin transactivates COX-2 promoter activity, whereas a dominant negative mutant of NFAT inhibited COX-2 induction in colon carcinoma cell lines. Furthermore, mutation or deletion of NFAT binding sites in the human COX-2 promoter greatly diminished its induction by phorbol 12-myristate 13-acetate/calcium ionophore A23187. These findings demonstrate the presence and activation of NFAT in human colon carcinoma cells, with important implications in the regulation of genes involved in the transformed phenotype as COX-2.
Duque
Javier
J
Centro de Biología Molecular Severo Ochoa, Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Fresno
Manuel
M
Iñiguez
Miguel A
MA
D000595:Amino Acid Sequence; D000001:Calcimycin / Q000494:pharmacology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms; D051546:Cyclooxygenase 2; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D017384:Sequence Deletion; D013601:T-Lymphocytes / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D050778:NFATC Transcription Factors; C494003:NFATC1 protein, human; C494006:NFATC2 protein, human; D009687:Nuclear Proteins; D010446:Peptide Fragments; D012333:RNA, Messenger; D014157:Transcription Factors; D000001:Calcimycin; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D013755:Tetradecanoylphorbol Acetate