A. Schmidt et al., BASIC FIBROBLAST GROWTH-FACTOR CONTROLS THE EXPRESSION AND MOLECULAR-STRUCTURE OF HEPARAN-SULFATE IN CORNEAL ENDOTHELIAL-CELLS, European journal of biochemistry, 234(2), 1995, pp. 479-484
Cultured bovine corneal endothelial cells express 5-8 ng basic fibrobl
ast growth factor (bFGF)/mg cell protein and distribute it between the
intracellular and pericellular compartment. Confluent cultures retain
approximately 80% of the total bFGF intracellularly, whereas 20% is p
resent in the pericellular (trypsin-releasable) compartment. No bFGF c
an be detected in the culture medium. The presence of 1-2 ng/ml medium
of endogenous or exogenous (human recombinant) bFGF is sufficient to
support cell growth. Simultaneously, cells incorporate [S-35]sulfate a
nd [H-3]glucosamine into the sulfated proteoglycans associated with th
e cell layer at a rate that is three times higher than in the absence
of bFGF. The enhanced proteoglycan synthesis is accompanied by a,shift
in proteoglycan distribution. In control cells, cell-associated hepar
an sulfate accounts for about 30% of the total glycosaminoglycans, whe
reas under the influence of bFGF the amount of heparan sulfate increas
es to approximately 60%. At the same time, the molecular structure of
the heparan sulfate molecule undergoes bFGF-specific changes as indica
ted by the [S-35]oligosaccharide pattern generated by heparitinase I d
egradation. The proportion of [S-35]oligosaccharides with greater than
six monosaccharides decreases on account of disaccharides and tetrasa
ccharides under the influence of bFGF. Pretreatment of bFGF with neutr
alizing antibodies against bFGF abolishes its biological activity. The
results suggest a bFGF-dependent change in the rate of synthesis and
structural features of the membrane-associated heparan sulfate in corn
eal endothelial cells. The modification of the heparan sulfate structu
re could influence its bFGF-binding and antiproliferative activity.