Synthesis by schwann cells of basal lamina and membrane-associated heparan sulfate proteoglycans

Abstract

Primary cultures that contain only Schwann cells and sensory nerve cells synthesize basal lamina. The assembly of this basal lamina appears to be essential for normal Schwann cell development. In this study, we demonstrate that Schwann cells synthesize two major heparan sulfate-containing proteoglycans. Both proteoglycans band in dissociative CsCI gradients at densities <1.4 g/ml, and therefore, presumably, have relatively low carbohydrate-toprotein ratios. The larger of these proteoglycans elutes from Sepharose CL-4B in 4 M guanidine hydrochloride (GuHCI) at a Kay of 0.21 and contains heparan sulfate and chondroitin sulfate chains of Mr 21,000 in a ratio of ~3:1. This proteoglycan is extracted from cultures by 4 M GuHCI but not Triton X-100 and accumulates only when Schwann cells are actively synthesizing basal lamina. The smaller proteoglycan elutes from Sepharose CL-4B at a Kav of 0.44 and contains heparan sulfate and chondroitin sulfate chains of Mr 18,000 in a ratio of ~4:1. This proteoglycan is extracted by 4 M GuHCI or by Triton X-100. The accumulation of this proteoglycan is independent of basal lamina production. © 1985, Rockefeller University Press., All rights reserved.