Regulation of Synaptic Localization of the AMPA Receptor by Heparan Sulfate Proteoglycans

Heparan sulfate proteoglycans (HSPGs) contain a core protein and one or more heparan sulfate (HS) chains, which are comprised of linear polysaccharides interspersed with alternating glucosamine units and uronic acids. There are three types of HSPGs : transmembrane (syndecans) , glycosylphosphatidylinositol (GPI)-linked (glypicans) , and secreted (agrin and perlecan) . Because of their high negative charge, HS chains bind to many proteins, including fibroblast growth factors (FGF), bone morphogenetic proteins (BMPs) , Hedgehog, and Wnt proteins, as well as to lipases, apolipoproteins, cell adhesion proteins, and extracellular matrix proteins. In the recent decade, genetic studies from both vertebrates and invertebrates have highlighted the critical roles of HSPGs in development. Specifically, a number of studies have shown the importance of HSPG in central nervous system development.