Dysregulated activation of activator protein 1 in keratinocytes of atopic dermatitis patients with enhanced expression of granulocyte/macrophage-colony stimulating factor.
Keratinocytes of patients with atopic dermatitis produce high amounts of granulocyte/macrophage colony-stimulating factor, a factor essential for dendritic cell function and thus for the development of skin immune responses. In contrast to keratinocytes cultured from nonatopic, healthy individuals, granulocyte/macrophage colony-stimulating factor mRNA could be detected in unstimulated cultures of atopic dermatitis keratinocytes, and phorbol myristate acetate induced much greater granulocyte/macrophage colony-stimulating factor mRNA levels in these cells, although the decay kinetics were not altered. Using reporter gene (chloramphenicol acetyl transferase) analysis, a minimal granulocyte/macrophage colony-stimulating factor promoter was shown to confer constitutive and phorbol-myristate-acetate-induced regulation of transcriptional activity in keratinocytes, and significantly higher levels of chloramphenicol acetyl transferase activity were measured in lysates of unstimulated and phorbol-myristate-acetate-treated atopic dermatitis keratinocytes than in control keratinocyte cultures. Electrophoretic mobility shift assays showed that low levels of NF-kappa B binding activity could be induced by phorbol myristate acetate in both normal and atopic dermatitis keratinocytes. By contrast, activator protein 1 complexes were efficiently induced, and they were invariably present at higher levels in nuclear lysates of atopic dermatitis keratinocytes. Atopic dermatitis keratinocyte nuclear lysates had higher constitutive levels of c-Jun, and phorbol myristate acetate promoted an earlier and stronger expression of c-Jun, JunB, and of the phosphorylated forms of c-Fos. A dysregulated activation of activator protein 1 may be implicated in the molecular mechanisms leading to increased granulocyte/macrophage colony-stimulating factor expression in atopic dermatitis keratinocytes. J Invest Dermatol 115:1134-1143 2000
Pastore
S
S
Laboratory of Immunology, Istituto Dermopatico dell'Immacolata, IRCCS, Rome, Italy. pastore@idi.it
Giustizieri
M L
ML
Mascia
F
F
Giannetti
A
A
Kaushansky
K
K
Girolomoni
G
G
D000293:Adolescent; D000328:Adult; D003876:Dermatitis, Atopic / Q000378:metabolism* / Q000473:pathology*; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005260:Female; D005456:Fluorescent Dyes; D015870:Gene Expression; D017930:Genes, Reporter; D016762:Genes, fos; D016758:Genes, jun / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis*; D006801:Humans; D015603:Keratinocytes / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000235:genetics* / Q000502:physiology*
D005456:Fluorescent Dyes; D018808:Transcription Factor AP-1; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013755:Tetradecanoylphorbol Acetate