Fig 4. Sulfation of chondroitin sulfate proteoglycans from femoral head cartilage.

Sulfation of proteoglycans was determined by HPLC disaccharide analysis after digestion by chondroitinase ABC and ACII of chondroitin sulfate proteoglycans from the femoral head cartilage of wild-type (WT) and Impad1^D175N/D175N mice at birth. In parallel the same analysis was performed also in the Impad1 knock-out (Impad1^-/-) mouse studied by Frederick [19]. The amount of non sulfated disaccharide (ΔDi-0S) relative to the total amount of disaccharides (ΔDi-0S, ΔDi-4S and ΔDi-6S) is significantly increased in mutant mice compared to the wild-types indicating proteoglycan undersulfation. Interestingly, the level of proteoglycan undersulfation in mutants is similar to the Frederick’s knock-out mouse. Three mice per group were used; data are reported as mean ± SD (Student’s t-test, *p<0.05; ***p<0.001).