Coordinated induction of inducible nitric oxide synthase and GTP-cyclohydrolase I is dependent on inflammatory cytokines and interferon-gamma in HaCaT keratinocytes: implications for the model of cutaneous wound repair.
Recently we demonstrated a strong expression of inducible nitric oxide synthase (iNOS) and GTP-cyclohydrolase I (GTP-CH I) in the basal keratinocytes of the epidermis adjacent to the wound and of the hyperproliferative epithelium during wound healing. To identify possible mediators of iNOS and GTP-CH I expression during this process, we analyzed the regulation of iNOS and GTP-CH I expression in cultured human keratinocytes. We found a large and long lasting coinduction of iNOS and GTP-CH I expression upon simultaneous treatment of quiescent cells with inflammatory cytokines interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma, but not with serum growth factors. The stimulatory effect of interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma is strongly synergistic on iNOS and GTP-CH I expression, because these factors alone stimulated GTP-CH I expression, although to a much lesser extent. Furthermore, iNOS mRNA levels are not influenced at all by stimulation with IL-1beta and revealed only a weak induction after treatment with tumor necrosis factor-alpha and interferon-gamma. Induction of iNOS and GTP-CH I gene expression upon cytokine and interferon-gamma exposure is independent of de novo protein synthesis. Because these cytokines are present at the wound site, they might be responsible for iNOS and GTP-CH I induction during cutaneous repair. Serum, which is released upon hemorrhage, is likely to play no stimulatory role in iNOS and GTP-CH I induction during wound healing.
Frank
S
S
Zentrum der Pharmakologie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany.
Kolb
N
N
Werner
E R
ER
Pfeilschifter
J
J
D000975:Antioxidants / Q000494:pharmacology; D001708:Biopterins / Q000031:analogs & derivatives / Q000502:physiology; D002460:Cell Line; D016207:Cytokines / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000097:blood; D006136:GTP Cyclohydrolase / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D015603:Keratinocytes / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D010982:Platelet-Derived Growth Factor / Q000032:analysis; D012333:RNA, Messenger / Q000378:metabolism; D012879:Skin Physiological Phenomena / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects; D014945:Wound Healing / Q000187:drug effects
D000975:Antioxidants; D016207:Cytokines; D007375:Interleukin-1; D010982:Platelet-Derived Growth Factor; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D001708:Biopterins; D004815:Epidermal Growth Factor; D007371:Interferon-gamma; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D006136:GTP Cyclohydrolase; C003402:sapropterin