Glycosaminoglycan and collagen metabolism in arylsulfatase B-deficient retinal pigment epithelium in vitro.

ABSTRACT

Regional differences in retinal pigment epithelial (RPE) cell glycosaminoglycan (GAG) and collagen metabolism were studied using cells obtained from normal cats and those with deficient activity of arylsulfatase B (ASB), a lysosomal enzyme involved in GAG catabolism. Control and ASB-deficient RPE cultures initiated from superior equatorial (superior) and inferior equatorial (inferior) regions of the eye were radiolabeled for 72 hr with 35SO4, and GAGs from the media and cell layers were analyzed separately. In ASB-deficient RPE, there was an accumulation of dermatan/chondroitin sulfate in the cell layer of cultures initiated from the superior region of the eye but not in those initiated from the inferior region. This agrees with previous in situ and in vitro morphologic observations that accumulation of inclusions in ASB-deficient RPE was greater in the superior region of the eye than in the inferior region. By contrast, media from ASB-deficient cultures initiated from the inferior region of the eye contained much higher levels of radiolabeled dermatan/chondroitin sulfate than ASB-deficient cultures from the superior region or normal cultures. Increased GAG content in the media may result from increased secretion of proteoglycans, increased turnover of cell surface or extracellular matrix components, or extrusion of lysosomal contents. These results indicate that one or more of these mechanisms vary regionally throughout the eye in the RPE of ASB-deficient animals. Collagen production was determined in normal and ASB-deficient RPE cultures. In normal RPE, no differences in collagen synthesis were noted between the inferior and superior regions.(ABSTRACT TRUNCATED AT 250 WORDS)