Abstract
We have analyzed the pattern of protein synthesis in solar near ultraviolet (334 nm, 365 nm) and near visible (405 nm) irradiated normal human skin fibroblasts. Two hours after irradiation we find that one major stress protein of approximately 32 kDa is induced in irradiated cells. This protein is not induced by ultraviolet radiation at wavelengths shorter than 334 nm and is not inducible by heat shock treatment of these cells. Although sodium arsenite, diamide, and menadione all induced a 32-kDa protein, they also induced the major heat shock proteins. In contrast, the oxidizing agent, hydrogen peroxide, induced the low molecular weight stress protein without causing induction of the major heat shock proteins. A comparison of the 32-kDa proteins induced by sodium arsenite, H2O2, and solar near ultraviolet radiation using chemical peptide mapping shows that they are closely related. These results imply that the pathways for induction of the heat shock response and the 32-kDa protein are not identical and suggest that, at least in the case of radiation and treatment with H2O2, the 32-kDa protein might be induced in response to cellular oxidative stress. This conclusion is supported by the observation that depletion of endogenous cellular glutathione prior to solar near ultraviolet irradiation lowers the fluence threshold for induction of the 32-kDa stress protein.
Highlights
We have analyzed the pattern of protein synthesis in solar near ultraviolet (334 nm, 365 nm) and near visible (405 nm) irradiated normalhuman skin fibroblasts
The exposureof mammalian cells to elevated temperature and to a wide variety of chemicals,includingredox-active compounds, induces the synthesisof a number of stress proteins while lowering the production of most other cellular proteins.At least in the case of the heat shock response, a functional role for the induced proteins is suggested by the observation that theacquisition of thermotolerance in Chinese hamstecrells correlates in time with the appearance of the major stress proteins [11]
In viewof the evidence linking the biological effects of solar UVA radiations to the productionof reactive oxygen species, including anionic species thought to be important intermediates in tumor promotion [13, 14], we have analyzed the pattern of protein synthesis in normal human skinfibroblasts following irradiationwithmonochromatic ultravioletradiationsinthe range 254-405 nmusingonedimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis
Summary
UVA and Near Visible Radiations Induce the Synthesis of a cytotoxic to mammaliancells [1,2] and may have tumor3-2-kDa Stress Protein-Fig. 1, A and B, shows the patternof promoting activity [3, 4]. Protein onine was optimal for detection of the UVA-induced stress protein In contrast to UVA irradiation, heat shock did not induce the synthesis of a 32-kDa stress protein. B , relative level of p32 synthesis as a function of surviving fraction following irradiation a t UV wavelengths between 313 and 405 nm. The relative level of p32 synthesis following increasing fluences of UV radiation a t each of the wavelengths indicated was calculated as above and plotted against thesurviving fraction of cells as measured after identical radiation treatments. Survival data for EK4 fibroblastas t each of the UV wavelengths employedwere derived
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