Activation of NF-κB in human skin fibroblasts by the oxidative stress generated by UVA radiation

We have examined the role of the nucleus and the membrane in the activation of nuclear factor (NF)-kB by oxidant stress generated via the UVA (320-380 nm) component of solar radiation. Nuclear extracts from human skin fibroblasts that had been irradiated with UVA at doses that caused little DNA damage contained activated NF-κB that bound to its recognition sequence in DNA. The UVA radiation-dependent activation of NF-κB in enucleated cells confirmed that the nucleus was not involved. On the other hand, UVA radiation-dependent activation of NF-κB appeared to be correlated with membrane damage, and activation could be prevented by α-tocopherol and butylated hydroxytoluene, agents that inhibited UVA radiation-dependent peroxidation of cell membrane lipids. The activation of NF-κB by the DNA damaging agents UVC (200-290 nm) and UVB (290-320 nm) radiation also only occurred at doses where significant membrane damage was induced, and, overall, activation was not correlated with the relative levels of DNA damage induced by UVC/UVB and UVA radiations. We conclude that the oxidative modification of membrane components may be an important factor to consider in the UV radiation-dependent activation of NF-κB over all wavelength ranges examined. (Author)