Proteoglycan synthesis in flat cell-free cultures of chick embryo retinal neurons and photoreceptors.
Extracellular matrix and cell surface proteoglycans are thought to play important roles in neural development and regeneration. Central nervous system proteoglycans have been isolated and characterized from rat and sheep brain and from chick neural retina. An experimental advantage offered by the latter tissue is that it is avascular and can be isolated free of connective tissue and pigment epithelium. Therefore, proteoglycans synthesized by this tissue are derived exclusively from neural cells. However, it has not yet been determined whether neurons and photoreceptors contribute to proteoglycan synthesis or whether these molecules are largely glial in origin. In the present study we have addressed this question using cultures of chick neural retinal cells free of flat, glial-like cells. Proteoglycans synthesized by cultures of retinal neurons, photoreceptors, and undifferentiated, process-free round cells from 8-day embryonic chick neural retina were metabolically labeled in vitro using [35S]sulfate and [3H]glucosamine as precursors. Radiolabeled proteoglycans accumulated in the medium, and could also be extracted from the cell layer by sequential treatments with Triton X-100 and with guanidine HCl. The proteoglycans were isolated by ion-exchange chromatography, and characterized by gel filtration chromatography and by susceptibility to degradation by enzymatic and chemical treatments. Overall, heparan sulfate proteoglycans were the predominant type of proteoglycan synthesized in vitro by the cultured neural retinal cells at this developmental stage. The medium and the Triton extract contained different proportions of both chondroitin sulfate and heparan sulfate proteoglycans, while heparan sulfate was the only proteoglycan recovered from the guanidine extract. These studies demonstrate that heparan sulfate and chondroitin sulfate proteoglycans are actively synthesized by cultures of neural retinal cells free of flat, glial-like cells.
Needham
L K
LK
Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205.
Adler
R
R
Hewitt
A T
AT
D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D011508:Chondroitin Sulfate Proteoglycans / Q000096:biosynthesis; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate / Q000096:biosynthesis; D008858:Microscopy, Phase-Contrast; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000378:metabolism*; D011509:Proteoglycans / Q000096:biosynthesis*; D012160:Retina / Q000166:cytology / Q000378:metabolism*
D011508:Chondroitin Sulfate Proteoglycans; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate; D011509:Proteoglycans