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Biosynthesis of dermatan sulphate. Loss of C-5 hydrogen during conversion of D-glucuronate to L-iduronate.

ABSTRACT: The formation of L-iduronic acid during biosynthesis of dermatan sulphate has been studied in culture human fibroblasts and in microsomes from the same cells. The cells were incubated with D-[14C]glucose and D-[5-3H]glucose for 72 h. The [14C,3H]dermatan sulphate was hydrolysed and the disaccharides obtained were acetylated and separated by ion-exchange chromatography. The ratio of 3H/14C was 0.36 for N-acetyldermosine and 1.36 N-acetylchondrosine. A microsomal preparation from the fibroblasts was incubated with UDP-D-[5-3H]glucuronic acid, UDP-D-[14C]glucuronic acid, UDP-N-acetyl-D-galactosamine and 3'-phospho-5'-adenylyl sulphate. The polymeric products were separated into nonsulphated and sulphated components which had 3H/14C ratios of 0.51 and 0.20 and contained 9% and 70% of their uronosyl residues in the L-ido-configuration, respectively. Chondroitinase-AC digestion of these polymers liberated all of the remaining 3H activity. Hydrolysis and N-acetylation followed by paper chromatography showed that the L-iduronic acid-containing products were devoid of 3H. The data obtained indicate that the epimerization of D-glucuronosyl to L-iduronosyl residues during biosynthesis of dermatan sulphate involves an abstraction of the C-5 hydrogen of the uronosyl residue.

SUBMITTER: Malmstrom A

PROVIDER: S-EPMC1163316 | biostudies-other | 1981 Sep

REPOSITORIES: biostudies-other

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Iduronate-2-Sulfatase-Regulated Dermatan Sulfate Levels Potentiate the Invasion of Breast Cancer Epithelia through Collagen Matrix.

Project description:Cancer epithelia show elevation in levels of sulfated proteoglycans including dermatan sulfates (DS). The effect of increased DS on cancer cell behavior is still unclear. We hypothesized that decreased expression of the enzyme Iduronate-2-sulfatase (IDS) can lead to increased DS levels, which would enhance the invasion of cancer cells. Breast cancer sections shows depleted IDS levels in tumor epithelia, when compared with adjacent untransformed breast tissues. IDS signals showed a progressive decrease in the non-transformed HMLE, transformed but non-invasive MCF-7 and transformed and invasive MDA-MB-231 cells, respectively, when cultured on Type 1 collagen scaffolds. DS levels measured by ELISA increased in an inverse-association with IDS levels. Knockdown of IDS in MCF-7 epithelia also increased the levels of DS. MCF-7 cells with depleted IDS expression, when imaged using two photon-excited fluorescence and second harmonic generation microscopy, exhibited a mesenchymal morphology with multiple cytoplasmic projections compared with epithelioid control cells, interacted with their surrounding matrix, and showed increased invasion through Type 1 collagen matrices. Both these traits were phenocopied when control MCF-7 cells were cultivated on Type 1 collagen gels polymerized in the presence of DS. In monolayer cultures, DS had no effect on MCF-7 migration. In the context of our demonstration that DS enhances the elastic modulus of Type 1 collagen gels, we propose that a decrease of IDS expression leads to accumulation within cancer epithelia of DS: the latter remodels the collagen around cancer cells leading to changes in cell shape and invasiveness through fibrillar matrix milieu.

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Biosynthesis and secretion of dermatan sulphate proteoglycans in cultures of human skin fibroblasts.

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Colorimetric measurement of dermatan sulphate.

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