Ultraviolet‐A induces activation of AP‐1 in cultured human keratinocytes

Abstract
UV‐A irradiation induces a time‐dependent activation of AP‐1 in NCTC 2544 human keratinocytes. 4 h after irradiation, a 2–3‐fold increase in AP‐1 activity is observed in human keratinocytes and fibroblasts. Activation is still detectable 24 h later. The UV‐A induced AP‐1 binding complex is shown to contain c‐Fos and c‐Jun proteins. Lipophilic vitamin E impedes UV‐A induced lipid peroxidation but does not prevent AP‐1 activation which is inhibited by N‐acetylcysteine, a hydrophilic antioxidant. This finding suggests that UV‐A‐dependent AP‐1 activation is sensitive to the cellular redox state but is not related to membrane lipid peroxidation.

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