Heparan sulfate and control of cell division: adhesion and proliferation of mutant CHO-745 cells lacking xylosyl transferase

Abstract

We have examined the role of cell surface glycosaminoglycans in cell division: adhesion and proliferation of Chinese hamster ovary (CHO) cells. We used both wild-type (CHO-K1) cells and a mutant (CHO-745) which is deficient in the synthesis of proteoglycans due to lack of activity of xylosyl transferase. Using different amounts of wild-type and mutant cells, little adhesion was observed in the presence of laminin and type I collagen. However, when fibronectin or vitronectin was used as substrate, there was an enhancement in the adhesion of wild-type and mutant cells. Only CHO-K1 cells showed a timedependent adhesion on type IV collagen. These results suggest that the two cell lines present different adhesive profiles. Several lines of experimental evidence suggest that heparan sulfate proteoglycans play a role in cell adhesion as positive modulators of cell proliferation and as key participants in the process of cell division. Proliferation and cell cycle assays clearly demonstrate that a decrease in the amount of glycosaminoglycans does not inhibit the proliferation of mutant CHO-745 cells when compared to the wild type CHO-K1, in agreement with the findings that both CHO-K1 and CHO-745 cells take 8 h to enter the S phase.

The never-ending story of peptide O -xylosyltransferase

“…Thus it would seem obvious that xylosyltransferase is, as the first enzyme in the biosynthesis of many proteoglycan side chains, probably crucial for animal life. Cultured cells can, though, survive without xylosyltransferase, as shown by the existence of the mutant Chinese hamster ovary cell line S745 (pgsA-745) [108], which has different adhesion properties but the same proliferation time as wild-type K1 cells [109]; this shows that xylosyltransferase is not required for survival of single eukaryotic cells (considering that yeasts lack this enzyme anyway). However, proteoglycans often mediate interactions between cells; thus, one would expect an obvious phenotype to be mediated by xylosyltransferase mutants in whole multicellular organisms.…”

Heparanase-2, syndecan-1, and extracellular matrix remodeling in colorectal carcinoma

“…The syndecan family is a transmembrane cell surface proteoglycan composed by HS chains covalently attached to the protein core [9,10]. Heparan sulfate proteoglycans (HSPG) play an important role in cellular recognition, growth control, and cellular adhesion because of interactions with different molecules at the cell surface and in the ECM [4,6,11]. These interactions occur mainly through the specific structure of the HS chains and less frequently through the protein core [12][13][14].…”

Fucan Inhibits Chinese Hamster Ovary Cell (CHO) Adhesion to Fibronectin by Binding to the Extracellular Matrix

“…However, we have previously shown that although there is a negligible amount of glycosaminoglycans present in CHO-745, attachment to FN is not affected [15]. The results strongly suggest that the anti-adhesive effect of fucan B is not related to the GAG content of the cell surface.…”