TPA and cycloheximide modulate the activation of NF‐κB and the induction and stability of nitric oxide synthase transcript in primary neonatal rat hepatocytes

[摘要]

12-O-Tetradecanoylphorbol 13-acetate (TPA) elicited a transient increase in the transcription of the inducible nitric oxide synthase (iNOS) gene coupled with a shortening of the half-life of its mRNA in primary neonatal rat hepatocytes. These effects of TPA were preceded by a surge in nuclear translocation of the transcription factor NF-κB, and followed by a mounting accumulation of NO₂ ⁻ in the growth medium. Even cycloheximide (CHX) added by itself elicited an early, sustained activation of NF-κB followed by an intense induction of iNOS gene expression, irrespective of what degree of protein synthesis inhibition was brought about by the several concentrations tested. When given together, TPA and CHX exerted additive effects on hepatocellular iNOS mRNA levels. These results suggest the likelihood of an ordered sequence of events by which an activated NF-κB mediates the induction of iNOS gene expression in TPA- and/or CHX-treated primary hepatocytes.

[学科分类] 生物化学/生物物理

[关键词] Primary liver culture;Gene expression;Nitric oxide synthase;NF-κB;12-O-Tetradecanoylphorbol 13-acetate;Cycloheximide;Act. D;actinomycin D;CHX;cycloheximide;CcNOS;constitutive NO synthase;EGF;epidermal growth factor;EMSA;electrophoretic mobility shift assay;FBS;foetal bovine serum;IFN-γ;interferon-γ;iNOS;inducible NO synthase;LPS;(bacterial) lipopolysaccharide;MEM;minimum essential medium;NO;nitric oxide;PDTC;pyrrolidine dithiocarbomate;TGF-β;transforming growth factor-β;TPA;12-O-tetradecanoylphorbol 13-acetate