Cell surface heparan sulfate proteoglycan (HSPG) (HSPG)

Cell surface heparan sulfate proteoglycans (HSPGs) are a diverse class of glycoproteins, primarily comprising the syndecan and glypican families, that are prominently expressed on the plasma membranes of macular retina cells and within the retinal extracellular matrix (Source: PMID 15615933). These molecules consist of a core protein decorated with heparan sulfate glycosaminoglycan chains, which facilitate interactions with a vast array of ligands, including growth factors, cytokines, and morphogens (Source: UniProt). In the macula, HSPGs are essential for maintaining the structural integrity of the blood-retinal barrier and modulating signaling pathways such as VEGF and FGF, which are critical drivers of neovascularization in diseases like wet age-related macular degeneration (AMD) (Source: NIH). Furthermore, HSPGs serve as the primary attachment receptors for several Adeno-associated virus (AAV) serotypes, such as AAV2, making them pivotal for the success of ocular gene therapies like Voretigene neparvovec (Source: PMID 21677681). Pathologically, alterations in the sulfation patterns of retinal HSPGs can disrupt the binding of regulatory proteins like Complement Factor H, leading to the chronic inflammation and complement overactivation characteristic of geographic atrophy (Source: Journal of Biological Chemistry). Consequently, HSPGs represent a multifaceted therapeutic target, serving as both a delivery portal for genetic medicines and a regulatory hub for inflammatory and angiogenic signaling in the eye.

Other names

Membrane-associated heparan sulfate proteoglycansSyndecansGlypicansCell surface HSPGsRetinal heparan sulfate proteoglycans

HSPGs serve as primary attachment receptors for viral vectors (e.g., AAV2) and act as co-receptors for pro-angiogenic growth factors like VEGF and FGF. They also provide critical binding sites for regulatory proteins such as Complement Factor H to prevent overactivation of the complement cascade on the cell surface.