ALTERATIONS OF PROTEOGLYCANS IN ULTRAVIOLET-IRRADIATED SKIN

The effect of UVB exposure on the distribution and synthesis of dermal proteoglycans was measured in the skin of hairless mice. Two groups o f mice were included: one was irradiated for 10 weeks; the other was k ept as control. After intraperitoneal injection of sodiUM S-35-sulfate , punch biopsies were taken for histology and proteoglycans were extra cted from the remaining skin with 4 M guanidinium chloride, containing 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (0.5%, wei ght per volume). Following proteolytic digestion, the glycosaminoglyca n constituents were isolated and analyzed by quantitative cellulose ac etate electrophoresis and enzymatic digestibility. Under the influence of UVB radiation, newly synthesized proteoglycans measured by (SO4)-S -35 uptake increased as much as 60%. In addition, the irradiated skin had a higher average content of proteoglycan than had control skin (49 81 mug vs 4134 mug/g dry weight). This could be ascribed to an increas e in heparin (1400 vs 533 mug/g dry weight) and heparan sulfate (472 v s 367 mug/g dry weight), whereas no change in the concentration of hya luronic acid (1243 vs 1372 mug/g dry weight) and dermatan sulfate (I 8 66 vs 1863 mug/g dry weight) was observed. The irradiated animals also exhibited a marked increase in the synthesis of heparan sulfate and h eparin (62% and 71%, respectively). These results demonstrate that chr onic doses of UVB altered proteoglycan metabolism through both quantit ative and qualitative changes.