Isolation and functional analysis of syndecans

Abstract

Syndecans comprise a major family of cell surface heparan sulfate proteoglycans (HSPGs). Syndecans are composed of sulfated glycosaminoglycans (GAGs), heparan sulfate (HS) or both HS and chondroitin sulfate (CS), attached covalently to core proteins. Syndecans regulate many cellular processes, such as adhesion, proliferation, and migration. Syndecans bind and regulate molecules primarily through their HS chains, but do not bind to all HS/heparin-binding molecules. Furthermore, mice ablated for the syndecan-1 or -4 gene do not show major developmental abnormalities, but they do show striking pathological phenotypes when challenged with infectious or inflammatory stimuli and conditions, suggesting that certain functions of syndecans are specific and cannot be compensated for by other syndecans or other HSPGs. These observations underscore the physiological importance of syndecans and indicate a need to study the activities of isolated native syndecans to define their molecular and cellular functions, and to establish their biological significance. Here we describe methods to isolate syndecans and several assays to analyze their functions.

Heparan Sulfate Proteoglycan Signaling in Tumor Microenvironment

“…Additional modifications occur at the cell surface or ECM through the action of 6-O-endo-sulfatases and/or the endoglycosidase heparanase. The controlled biosynthesis and post-synthetic modifications of HS chains provide an enormous potential of heterogeneity and structural variability of HS chains which accounts for a wide variety of HSPG interactions with regulatory proteins and, in turn, for their biological activities [12][13][14][15]43]. Several studies have demonstrated that there are cell and tissue-specific changes in the HS chain synthetic pathway in cancer cells and tissues in vitro and in vivo, thus suggesting a close involvement of HS chain biosynthetic machinery in carcinogenesis [30,44,45].…”

Heparan Sulfate Proteoglycans in Human Colorectal Cancer

“…Similarly, syndecan-4, which is mainly involved in cytoskeletal and membrane reorganization and formation of focal adhesions, inhibits cell migration and tumor activity [ 63 ]. Consistently, mRNA expression of syndecan-1 and syndecan-4 is significantly reduced in colon carcinoma cells [ 40 ]. However, in different types of cancers, syndecan-1 and syndecan-4 may present the opposite effect, promoting the tumor progression [ 64 , 65 ].…”

“…The syndecans regulate cell adhesion, migration, cytoskeleton organization, and gene expression through the binding of ECM molecules and soluble ligands [ 40 ]. Since cancer cells exhibit less adhesive and more migratory characteristics in comparison to normal cells, syndecans are candidate molecules to be differently regulated in cancer cells.…”

Cleavage of proteoglycans, plasma proteins and the platelet-derived growth factor receptor in the hemorrhagic process induced by snake venom metalloproteinases

“…Cell-surface syndecans links the cytoskeleton to the interstitial matrix by means of heparan sulfate chains and is expressed on leukocytes and endothelial cells. Syndecans regulate many cellular processes, such as adhesion, proliferation, and migration, and are susceptible to shedding by proteinases, resulting in the release of ectodomains that can act as competitive inhibitors of their cell surface-linked counterparts 93 – 95 and modulate the onset of different pathological processes 96 – 98 . Considering the role of syndecan-1 in the endothelial glycocalyx, its degradation in the hemorrhagic process generated by HF3 in the mouse skin suggests the impairment of its functions with consequences related to glycocalyx permeability and mechanotransduction of fluid shear stress, as well as to leukocyte access to endothelial tissue.…”