Marked Expression of Glutathione S-Transferase A4-4 Detoxifying 4-Hydroxy-2(E)-nonenal in the Skin of Rats Irradiated by Ultraviolet B-Band Light (UVB)

Abstract

Enzyme, Western blot, and immunohistochemical analyses indicated that rat skin cytosol contained no detectable level of the homodimeric, alpha-class glutathione S-transferase (rGST) A4-4 which catalyzes the GSH conjugation of the toxic product, 4-hydroxy-2(E)-nonenal (HNE), nonenzymatically formed from n-6 polyunsaturated fatty acid residues of lipids by lipid peroxidation. Rats irradiated by single doses (4000–24,000 mJ/cm2) of ultraviolet B-band light (UVB, 200 mJ/cm2/min) markedly expressed rGSTA4-4 in the skin at a level one-fifth that of the liver in apparent specific activity toward HNE at a single dose of 24,000 mJ/cm2. Skin rGSTA4-4 was isolated, purified to homogeneity, and identified with hepatic rGSTA4-4 by reverse-phase partition HPLC and by amino acid sequence analysis of its CNBr fission peptides. Immunohistochemistry with polyclonal antibody raised against rGSTA4-4 demonstrated the selective expression of rGSTA4-4 in epidermis and sebaceous glands localized in dermis after UVB irradiation.