Binding of FGF-1 and FGF-2 to heparan sulphate proteoglycans of the mammalian lens capsule.

In the mammalian eye, FGF plays a key role in the induction of lens fibre differentiation and, in other systems, heparan sulphate proteoglycans (HSPGs) have been shown to modulate FGF activity. HSPGs were isolated from the anterior and posterior rat and bovine lens capsule and assessed in terms of their ability to bind FGF-1 and FGF-2. In the rat, at least four HSPGs were identified with molecular weights of 142, 166, 200 and approximately 250 kD, the latter species predominating. The capsule HSPGs bound both FGF-1 and FGF-2. There appeared to be little, if any, competition for binding between FGF-1 and FGF-2. The capsule contained substantial amounts of core protein, which did not bind FGF, with a higher core protein/HSPG ratio in the anterior than in the posterior capsule. This was the only major HSPG-related difference noted between anterior and posterior capsule.