Heparan sulfate proteoglycans HSPGs

The rationale for this type of contrast agent is to use the endogenous metabolic pathway of lipid metabolism in the liver for the transport of iodinated substances. Chylomicron remnants are naturally occurring lipoproteins in the blood that are responsible for the transport of lipids into the liver. Three different mechanisms for this transport are discussed direct uptake by the low-density lipoprotein receptor transport to the low-density lipoprotein receptor-related protein (LRP) mediated by heparan sulfate proteoglycan (HSPG) or direct HSPG-LRP uptake and direct HSPG uptake. One of the prerequisites for particles to be transported by these mechanisms is a mean diameter of less than 100-300 run. 

Already in 1965, Ryser and Hancock provided evidence that histones and polyamino acids could greatly enhance albumin uptake by cultured tumor cells (6). More recently, several polybasic peptides (so-called protein transduction domains, PTDs or cell-penetrating peptides, CPPs) have been shown to efficiently mediate uptake of nucleic acids, bioactive peptides, phage particles, and liposomes into a wide variety of mammalian cells. The initially proposed ability of CPPs to penetrate plasma membranes via a temperature-independent, non-endocytotic pathway was later shown to be a fixation artifact, and it is currently widely accepted that CPP-mediated macromolecular delivery follows energy-dependent endocytotic pathways that in most cases depend on the expression of cell-surface heparan sulfate proteoglycans (HSPGs) (7). 

Sarafanov AG, Ananyeva NM, Shima M, et al Cell surface heparan sulfate proteoglycans (HSPGs) par-... 

Middle Cerebral Artery Occlusion (MCAO) Assay and Vascular Heparan Sulfate Proteoglycans (HSPG) Perlecan Assay... 

The most complete structural information about sulfate-dependent protein interactions is available from extensive studies on the many interactions of heparan sulfate proteoglycans (HSPGs). Via their covalently attached heparan sulfate chains, HSPGs bind to a large array of growth factors, cytokines, chemokines, extracellular matrix proteins, cell-cell adhesion molecules, viral attachment receptors, blood coagulation components, and lipid carrier molecules [18 21], Among the functions served by these interactions are ... 

Heparan sulfate proteoglyeans also play a role in the uptake of lipoproteins by vaseular cells [95, 96], This activity is related to the ability of HSPGs to bind lipoprotein lipase, which serves as a bridging molecule between the lipoprotein and the proteoglycan. 

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