Biochemical studies on the sulphated glycosaminoglycan fraction of skin fibroblasts cultured from a patient with the Hurler syndrome

Abstract

1. The metabolism of the sulphated glycosaminoglycan fraction in cultured skin fibroblasts derived from a patient with the Hurler syndrome and from a normal subject was studied. Two labelled precursors, Na235SO4 and d-[2-3H]glucose, were used and their intracellular fates during uptake and `chase' periods were assessed after separation of sulphated glycosaminoglycans from hyaluronic acid. After 4 or 8h of exposure to culture medium containing both labels, [35S]sulphate incorporation into the sulphated glycosaminoglycan fraction was twofold greater in Hurler-syndrome cells than in normal cells. At the same time, the rate of incorporation of [3H]glucose into the sulphated glycosaminoglycan fraction was approximately the same for both cell types. Consequently, an increased 35S/3H ratio (nmol of [35S]sulphate incorporated/nmol of [3H]glucose incorporated) was observed for Hurler-syndrome cells compared with normal cells. 2. The results of `chase' experiments revealed that although the expected loss and relative retention of labelled sulphate occurred in the sulphated glycosaminoglycan fraction of normal and Hurler-syndrome cells, both cell types retained all of their radioactivity derived from [3H]glucose. 3. After 34h exposure to a `corrective-factor' preparation from urine, the sulphated glycosaminoglycan content (as hexosamine and [35S]sulphate) of the Hurler-syndrome cells approached normal values. At the same time, there was an increase in specific radioactivity of `corrected' Hurler-syndrome cells.