Extracellular accumulation of small dermatan sulphate proteoglycan II by interference with the secretion-recapture pathway.
Human skin fibroblasts were metabolically labelled in the presence of affinity-purified antibodies against the core protein of small dermatan sulphate proteoglycan II. The treatment resulted in a dose- and time-dependent accumulation of this proteoglycan in the culture medium, with a 2-3-fold increase found within an experimental period of 4 h. The presence of antibodies was without influence on the rate of biosynthesis of the proteoglycan. However, proteoglycan-antibody complexes were inefficiently endocytosed. Addition of unlabelled proteoglycan, which served as a competitor for uptake, similarly led to an accumulation of newly formed [35S]sulphate-labelled proteoglycans. Proteoglycan accumulation also occurred as a consequence of its binding to collagen fibrils which were physically separated from the cell layer. Together, these results establish the quantitative importance of the secretion-recapture pathway of small dermatan sulphate proteoglycan II in cultured fibroblasts.
Schmidt
G
G
Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Federal Republic of Germany.
Hausser
H
H
Kresse
H
H
D002478:Cells, Cultured; D002807:Chondroitin / Q000031:analogs & derivatives*; D003094:Collagen / Q000378:metabolism; D003871:Dermatan Sulfate / Q000378:metabolism*; D004705:Endocytosis; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D007158:Immunologic Techniques; D066298:In Vitro Techniques; D011509:Proteoglycans / Q000378:metabolism*; D012867:Skin
D011509:Proteoglycans; D003871:Dermatan Sulfate; D002807:Chondroitin; D003094:Collagen