Thromb Haemost 1994; 72(01): 092-097
DOI: 10.1055/s-0038-1648818
Original Article
Schattauer GmbH Stuttgart

Different Regulation of Plasminogen Activator Inhibitor 2 Gene Expression by Phorbol Ester and cAMP in Human Myeloid Leukemia Cell Line PL-21

Authors

  • Kenji Niiya

    1   The Department of Clinical Laboratory Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama
  • Taketoshi Taniguchi

    2   Medical Research Laboratory, Kochi Medical School, Nankoku, Kochi, Japan
  • Masahiro Shinbo

    1   The Department of Clinical Laboratory Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama
  • Tai-ichi Ishikawa

    1   The Department of Clinical Laboratory Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama
  • Shigeki Tazawa

    1   The Department of Clinical Laboratory Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama
  • Yumiko Hayakawa

    1   The Department of Clinical Laboratory Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama
  • Nobuo Sakuragawa

    1   The Department of Clinical Laboratory Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama
Further Information

Publication History

Received 24 September 1993

Accepted after resubmission 01 March 1994

Publication Date:
12 July 2018 (online)

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Summary

Previous studies have shown that protein kinase C (PKC) activators and dibutyryl cyclic AMP (Bt2cAMP) synergistically increase the antigen level of plasminogen activator inhibitor type-2 (PAI-2) in a human myeloid leukemia cell line PL-21. To clarify the mechanism, PAI-2 gene expression induced by phorbol myristate acetate (PMA), a PKC activator, and Bt2cAMP was investigated by Northern blot hybridization using a PAI-2 cDNA probe cloned from a human placental library. The level of PAI-2 mRNA was markedly increased in response to PMA and reached a maximum 5-9 h after stimulation. Nuclear run-on assay revealed an increase in PAI-2 gene transcription in PMA-treated cells. The induction was inhibited by inhibiting de novo protein synthesis with cycloheximide (CHX). cAMP also increased PAI-2 mRNA level in a dose-dependent manner. The increase began within 2 hours and, contrary to the case of PMA, the mRNA levels were maintained. Moreover, cAMP-induced increase in PAI-2 mRNA was not inhibited by CHX, rather enhanced. PMA and cAMP synergistically induced PAI-2 gene expression, which was completely inhibited by CHX. The cells pretreated with PMA for 24 h did not any more respond to stimulation with PMA but responded to cAMP and PAI-2 mRNA level was increased. The apparent half-life of constitutive level PAI-2 mRNA in PL-21 cells, determined by actinomycin-D-decay experiments, was approximately 2 h. Those induced by PMA and cAMP were approximately 5 h and 2 h, respectively. These data suggest that PAI-2 mRNA induced by PMA is relatively stable and the expression requires de novo protein synthesis, whereas cAMP increases PAI-2 mRNA level without affecting the stability and the induction does not require de novo protein synthesis. Judging from these data, PAI-2 gene expression appears to be differently regulated by the PKC and cAMP signalling pathways.