Removal of Glycosaminoglycans from Bovine Granulosa Cells Contributes to Increased Binding of Hydrogen-3 Heparin

Abstract

Granulosa cells from small or large bovine follicles were pretreated with enzymes that hydrolyze various glycosaminoglycans, and binding of [3H]-heparin to the granulosa was measured. Binding of [3H] heparin increased significantly after enzymatic pretreatments with chondroitinase ABC and fungal hyaluronidase, and similar results were obtained with granulosa from small and large follicles. No changes in binding of [3H] heparin were detected after hydrolyses with chondroitinase AC and heparinase in either follicle size. Heparitinase, which hydrolyzes heparan sulfate, led to a significant 50% increase in binding of [3H] heparin to granulosa from large follicles but was without effect in small follicles. These results suggest that the lower binding of [3H] heparin, which has been reported with follicular enlargement, may be due to heparan sulfate occupying or obstructing binding sites for heparin on granulosa from large follicles.

Properties of heparin binding to purified plasma membranes from bovine granulosa cells

“…Conversely, follicular GAGs inhibit gonadotrophin binding to cell surface receptors (Amsterdam et al, 1979;Nimrod & Lindner, 1980) possibly by steric specific, saturable, reversible, and dependent on the pH and ionic composition of the medium. Other factors which influence GAG binding to granulosa cells include the maturation state of the follicle from which the cells are obtained (Ax et al, 1984;Bushmeyer et al, 1985;Bellin et al, 1987b), and the presence of GAGs already attached to the cell surface (Ax et al, 1986). The degree of sulphation of the GAG has also been shown to affect binding to mouse tumour cells (Winterbourne & Mora, 1981) and granulosa cells (Bellin et al, 1987b).…”