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Abstract: Objective: Lipid retention in the vessel wall by glycosaminoglycan (GAG) chains on chondroitin/dermatan sulfate proteoglycans synthesized by vascular smooth muscle cells (VSMC) have recently been established as an early event in human coronary artery atherosclerosis. GAG structure can be altered by growth factors resulting in enhanced binding to low density lipoprotein (LDL). The aim of this study was to determine if proteoglycans produced by endothelin-1 treated VSMCs had increased binding to human LDL, to examine the effect of endothelin-1 on the synthesis and structure of proteoglycans and to elucidate the signalling pathway. Methods and results: Endothelin-1 stimulated an increase in [35S]sulfate and [3H]glucosamine incorporation into proteoglycans produced by human VSMC. The increase was due to an increase in GAG chain size assessed by SDS-PAGE and size exclusion chromatography. Increased radiolabel incorporation was inhibited by an ETA but not an ETB receptor antagonist. Endothelin-1 stimulated an increase in the 6:4 position sulfation ratio on the disaccharides of the GAG chains, an effect that was blocked by bosentan. The EGF receptor antagonist AG1478 did not affect the increase in GAG size mediated by endothelin-1. Inhibition of protein kinase C (PKC) with GF109203X or down regulation by PMA pre-treatment attenuated the effect of endothelin-1 on GAG synthesis. Conclusion: These data demonstrate that endothelin-1 stimulates changes in GAG chain structure that increase binding to LDL. This action of endothelin-1 may represent a new target for the prevention of lipid binding within the vascular wall and the associated complications resulting from this interaction. [Copyright &y& Elsevier]

Abstract: Atherosclerosis is the primary ischaemic vascular condition underlying a majority of cardiovascular disease related deaths. Endothelin-1 is a vasoactive peptide agent upregulated in atherosclerosis and in conjunction with its G protein-coupled receptors exerts diverse actions on all cells of the vasculature in particular vascular smooth muscle cells (VSMC). The effects of endothelin-1 include cell proliferation, migration and contraction, and the induction of extracellular matrix components and growth factors. VSMC as the major component of the neointima in atherosclerotic plaques accordingly play a key role in atherogenesis. In this review we examine classic and novel signalling pathways activated by endothelin-1 in VSMC (including phospholipase C, adenylate cyclase, Rho kinase, transactivation of receptor tyrosine kinases, mitogen activated protein kinase cascades and β-arrestin) and their likely impact on the development and progression of atherosclerosis. [Copyright &y& Elsevier]