Fluid shear stress induces the clustering of heparan sulfate via mobility of glypican-1 in lipid rafts

Abstract

The endothelial glycocalyx plays important roles in mechanotransduction. We recently investigated the distribution and interaction of glycocalyx components on statically cultured endothelial cells. In the present study, we further explored the unknown organization of the glycocalyx during early exposure (first 30 min) to shear stress and tested the hypothesis that proteoglycans with glycosaminoglycans, which are localized in different lipid microdomains, respond distinctly to shear stress. During the initial 30 min of exposure to shear stress, the very early responses of the glycocalyx and membrane rafts were detected using confocal microscopy. We observed that heparan sulfate (HS) and glypican-1 clustered in the cell junctions. In contrast, chondroitin sulfate (CS), bound albumin, and syndecan-1 did not move. The caveolae marker caveolin-1 did not move, indicating that caveolae are anchored sufficiently to resist shear stress during the 30 min of exposure. Shear stress induced significant changes in the distribution of ganglioside GM1 (a marker for membrane rafts labeled with cholera toxin B subunit). These data suggest that fluid shear stress induced the cell junctional clustering of lipid rafts with their anchored glypican-1 and associated HS. In contrast, the mobility of CS, transmembrane bound syndecan-1, and caveolae were constrained during exposure to shear stress. This study illuminates the role of changes in glycocalyx organization that underlie mechanisms of mechanotransduction.

Heparan Sulfates Mediate the Interaction between Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1) and the Gαq/11 Subunits of Heterotrimeric G Proteins

“…The observation that both syndecan-1 and syndecan-4 interactions with PECAM-1 are increased at 60 s is consistent with flow-induced junctional clustering of glycocalyx components (i.e. HS and glypican-1), which has been recently reported to occur in rat fat pad endothelial cells at 30 min (42). In the case of HCAECs there seems to be a more rapid association of syndecans with the junction.…”

Endothelial Glycocalyx: Novel Insight into Atherosclerosis

“…Furthermore, selectively degradation of some specific components (such as HS) of the endothelial glycocalyx or silence of the specific gene (such as glypican-1) can inhibit the shear stress-induced activation of eNOS [66] and the production of NO in EC [67]. By using confocal microscopy, we discovered that 15 dyn/cm 2 shear stress induces remodeling of endothelial glycocalyx [11,16]. At initial 30 min, 15 dyn/cm 2 shear stress induces the junctional clustering of HS via mobility of GPI-anchored glypican-1 in lipid rafts (rapid change).…”

“…In the vascular remodeling due to AS, the structural and functional adaptive changes in vessels adapt to the mechanical (such as shear stress) and chemical (such as vasoactive mediators and cytokines) microenvironments, which involve various cell activities such as cell phenotype conversion [9] and remodeling of the extracellular matrix and endothelial glycocalyx [10][11][12][13][14]. It is well-known that flow patterns with shear stress magnitude are changed with development of AS [15].…”

“…It is well-known that flow patterns with shear stress magnitude are changed with development of AS [15]. Shear stress induces clustering of the major components of endothelial glycocalyx including glypican-1 with attached heparan sulfate (HS) [11,16]. S1P is a lipid mediator and mostly present in plasma that induces various cellular effects, including proliferation, differentiation, survival, and migration [17].…”

“…S1P is also emerging as a potent modulator of endothelial barrier function and vascular tone [18]. Recent studies demonstrated that sphingosine-1-phosphate (S1P) protects the endothelial glycocalyx against shedding and induces the synthesis of glycocalyx [11,16].…”