BETA-D-XYLOSIDE INDUCED MODULATIONS OF GLYCOSAMINOGLYCANS, PROLIFERATION, AND CYTOSKELETAL ORGANIZATION OF RAT-LIVER MYOFIBROBLAST-LIKE CELLS (TRANSFORMED FAT STORING CELLS)

Transformed fat storing cells, i.e. myofibroblast-like cells are the major source of proteoglycans in injured liver. In the present study p-nitrophenyl-beta-D-xylopyranoside (PNP-Xyl), a specific metabolic inhibitor of proteoglycan synthesis, was used to analyze some details of altered glycosaminoglycan metabolism, proliferation, morphology and cytoskeletal organization of myofibroblast-like cells (secondary cultures of fat storing cells) under conditions of abrogated proteoglycan synthesis. PNP-Xyl increased dose-dependently the synthesis of [S-35] sulfate-labelled medium glycosaminoglycans, among which chondroitin sulfate formation was stimulated predominantly. The distribution and composition of glycosaminoglycans in the cellular and cell surface compartments were affected differently. Production of medium hyaluronan was reduced by more than 40% at 5 mM PNP-Xyl. The compound inhibited dose-dependently the mitotic activity of myofibroblast-like cells without affecting viability. The morphologic appearance was changed at 5 mM PNP-Xyl and the organization and expression of desmin and smooth muscle iso-alpha-actin, both important markers of myofibroblast-like cells, were also modified by PNP-Xyl. Inhibition of proliferation, morphologic changes, and cytoskeletal disorganization were fully and rapidly reversible upon removal of the drug. The results support the notion of a direct or indirect role of proteoglycans in maintaining important functions of myofibroblast-like cells in culture.