Effects Of Ultraviolet B On The Signaling Of MAPK In Human Epidermal Keratinocyte

Objective: To investigate the regulation effects on MAPK signaling of ultraviolet B(UVB) irradiation in the human epidermal keratinocytes.Methods:Keratinocytes were exposed to 1.5, 4.5, 7.5,10, 20,30 or 50 m J/cm2 UVB, and non-exposed cells were used as control. Eight hours after exposure, protein expression levels of ERK1/2, JNK and p38 were determined by western blot in different dose groups. Then the epidermal keratinocytes were treated with 50 m J/cm2 of UVB radiation. At 2, 4, 8, 12 hours after exposure, western-blot was performed to examine the level of ERK1/2, JNK and p38 expression in epidermal keratinocytes respectively.Results:Eight hours after 7.5,10,20,30,50 m J/cm2 UVB exposure,phosphorylation of ERK1/2 and JNK were up-regulated significantly. Phosphorylation of p38 was also up-regulated after 20,30,50 m J/cm2 UVB exposure. Its had the most significant effects after 50 m J/cm2 UVB exposure(P<0.05).At the 2hour after 50 m J/cm2 UVB exposure, phosphorylation of p38 and JNK began to up-regulate significantly,and the up-regulated trend was enhanced with time. But the level of its phosphorylation of JNK attenuated by the time after UVB exposure(P<0.05). Phosphorylation of ERK1/2 was up-regulated at 8hour after UVB exposure(P<0.05), the level of its phosphorylation was significant elevated than that of control at 12hour(10.277±0.320 vs. 44.844±2.023, P<0.05).Conclusions: Our study suggest that ERK1/2, JNK and p38 MAPK pathways were activated by 50 m J/cm2 UVB radiation in epidermal keratinocytes, and the activation has difference dependent on time effect.