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Role of chondroitin sulphate in the uptake of β‐VLDL by brain cells
Author(s) -
Rapp Alfred,
Hüttinger Manfred
Publication year - 2005
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2005.04313.x
Subject(s) - apolipoprotein e , internalization , lipoprotein , receptor , very low density lipoprotein , chemistry , ldl receptor , apolipoprotein b , biochemistry , low density lipoprotein , cholesterol , microbiology and biotechnology , low density lipoprotein receptor related protein 8 , chondroitin sulfate , glycosaminoglycan , medicine , biology , disease
Proteoglycans (PGs) have been suggested to work as receptors in lipoprotein uptake mechanisms. An interaction between apolipoprotein E (apoE) and glucosaminoglycans (GAG), polysaccharides linked to proteoglycans, has been proposed in this pathway. At the same time, proteoglycans, apoE as well as lipoprotein receptors have been reported to be constituents of amyloid plaques, one hallmark of Alzheimer's disease. With this study, we are the first to investigate the interaction between beta very low density lipoprotein (β‐VLDL) and a neuronal highly abundant GAG, chondroitin sulphate (CS), comparing hippocampal neurons, expressing high levels of low density lipoprotein receptor related protein (LRP) and U373 astrocytoma cells, highly positive for the low density lipoprotein receptor (LDLR). We were able demonstrate that degradation of chondroitin sulphate proteoglycans (CSPGs) with chondroitinase ABC resulted in reduced 125 I‐β‐VLDL uptake. We showed that externally added CSs compete with internalization of β‐VLDL. The effect was found to be dose‐dependent, but was influenced neither by cell type, nor receptor type. The position of sulphation of added CSs showed only a slight influence. The data generated suggested an interaction between apolipoproteins and soluble CSs; therefore, 3 H‐cholesterol linked to apoE was coadministered with CSs to the cells. The results revealed that apoE bound, but no unbound cholesterol, was reduced in cellular internalization, suggesting that CSPGs may be involved in lipoprotein uptake in the intact brain, mediated, at least in part, by apoE.