Modulation of Peroxiredoxin I Expression by UVB Irradiation in Human Keratinocytes: H2O2-mediated Modulation of Peroxiredoxin I

Yun, Sook Jung; Lee, Jae Wook; Choi, Jee Young; Lee, Seung Chul

Abstract

BACKGROUND
Peroxiredoxin I (Prx I) is part of an oxidative stress defense system with thioredoxin peroxidase activity to eliminate hydrogen peroxide (H2O2). UV irradiation is one of the major sources to produce H2O2, which should then be scavenged by antioxidant systems to maintain functional integrity of the skin. OBJECTIVE: This study aimed to evaluate the modulation of Prx I by ultraviolet B (UVB) irradiation in human epidermal keratinocytes. The modulation of Prx I expression by H2O2 was also evaluated. METHOD: Primary culture of epidermal keratinocytes was performed, and sub-confluent cells were irradiated with UVB irradiation (20mJ/cm(2)). Western blot and Northern blot analysis were performed after the cells were harvested at different time-points after UVB irradiation. Prx I expression and intracellular levels of H2O2 were evaluated in the cells which had been irradiated with different doses of UVB. The localization of Prx I expression was identified by immunocytochemical staining. RESULTS: UVB irradiation induced Prx I mRNA and protein expressions from 3 h and 6 h after irradiation, respectively, indicating that UVB induced Prx I expression at a transcription level. Intracellular H2O2 levels were steadily increased as keratinocytes were irradiated with increasing doses of UVB. Next, when keratinocytes were treated with 0.1-10.0mM of H2O2, the marked induction of Prx I protein expression was observed above 1 mM H2O2 at a time-dependent manner (after 6 h). The H2O2-induced Prx I expression was abolished by N-acetyl-L-cysteine, a H2O2 scavenger, pre-treatment. In 2D-gel electrophoresis, the active reduced form of Prx I was rapidly transformed into the oxidized, inactive form, and then it restored to the reduced form by H2O2 treatment, suggesting that Prx I was active in responding to the H2O2-induced oxidative stress. CONCLUSION: UVB irradiation up-regulates Prx I by the mediation of H2O2 in the keratinocytes.