The Glycosaminoglycan Binding Site Governs Ligand Binding to the Somatomedin B Domain of Vitronectin

Seiffert, Dietmar

doi:10.1074/jbc.272.15.9971

Cited by 30 publications

(29 citation statements)

References 31 publications

(30 reference statements)

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“…Our results show that for heparin, the CD34 + culture outcomes ranged from minimal proliferation to extensive proliferation to full toxicity as a function of the heparin levels. This concentration effect is supported by reports that variations in GAG levels may play a significant role in the regulation of hematopoiesis [30,31]. Notably, the activities of IL-3 and GM-CSF were shown to increase as the concentration of heparan sulfate increased [30].…”

Section: Discussionsupporting

confidence: 65%

Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces

1999

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Recent studies have indicated that glycosaminoglycan (GAG) interactions with hematopoietic progenitors play a significant role in the regulation of hematopoiesis. However, the details of these interactions are not clear. In this study, we examined the role of soluble and immobilized GAGs in the proliferation of CD34 + cells. Chitosan, a cationic polysaccharide, was used to immobilize GAGs in ionic complex membranes. The GAGs studied were heparin, hyaluronate, and chondroitin sulfates A, B, and C. CD34-enriched umbilical cord blood cells were seeded onto tissue culture plates coated with the GAG-chitosan complex membranes. Cultures were maintained in medium supplemented with stem cell factor and interleukin 3 for up to six weeks, during which total and CD34 + cell numbers were determined by flow cytometry. Total cell number expansion ranged from 25-fold to 40-fold after six weeks. However, only heparin and chondroitin sulfate B (CSB) surfaces retained a significant CD34 + fraction. All other surfaces exhibited declines in CD34 expression, with negligible CD34 + percentages remaining after four weeks. In contrast, heparin and CSB surfaces exhibited CD34 + fractions as high as 90% after four weeks.GAG desorption studies indicated that the observed effects were partly mediated by desorbed GAGs in a concentration dependent manner. Subsequent studies showed that sustained high (160 g/ml) heparin levels had toxic effects, while the same concentration of CSB exhibited more rapid early proliferation of CD34 + cells. In conclusion, this culture system has demonstrated the ability to produce simultaneous proliferation and CD34 + cell enrichment of a partially purified cord blood population by controlling the nature and levels of GAG moieties to which the cells are exposed. The results indicate that specific GAGs can significantly influence the growth and differentiation characteristics of cultured CD34 + cells.

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Section: Discussionsupporting

confidence: 65%

Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces

1999

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“…Studies in other laboratories have indicated that multimerization of proteins can alter their ligand-binding capacity (Oh et al, 1997;Seiffert, 1997). We thus decided to test the effect of removing the Ena EVH2 domain on its affinity for the Abl-SH3 domains and zyxin.…”

Section: The Evh2 Domain Is Important For Ena's Ability To Bind the Amentioning

confidence: 99%

Mutations inDrosophilaEnabled and Rescue by Human Vasodilator-stimulated Phosphoprotein (VASP) Indicate Important Functional Roles for Ena/VASP Homology Domain 1 (EVH1) and EVH2 Domains

Ahern-Djamali

Comer

Bachmann³

et al. 1998

MBoC

110

101

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Drosophila Enabled (Ena) was initially identified as a dominant genetic suppressor of mutations in the Abelson tyrosine kinase and, more recently, as a member of the Ena/human vasodilator-stimulated phosphoprotein (VASP) family of proteins. We have used genetic, biochemical, and cell biological approaches to demonstrate the functional relationship between Ena and human VASP. In addition, we have defined the roles of Ena domains identified as essential for its activity in vivo. We have demonstrated that VASP rescues the embryonic lethality associated with loss of Ena function in Drosophila and have shown that Ena, like VASP, is associated with actin filaments and focal adhesions when expressed in cultured cells. To define sequences that are central to Ena function, we have characterized the molecular lesions present in two lethal ena mutant alleles that affected the Ena/VASP homology domain 1 (EVH1) and EVH2. A missense mutation that resulted in an amino acid substitution in the EVH1 domain eliminated in vitro binding of Ena to the cytoskeletal protein zyxin, a previously reported binding partner of VASP. A nonsense mutation that resulted in a C-terminally truncated Ena protein lacking the EVH2 domain failed to form multimeric complexes and exhibited reduced binding to zyxin and the Abelson Src homology 3 domain. Our analysis demonstrates that Ena and VASP are functionally homologous and defines the conserved EVH1 and EVH2 domains as central to the physiological activity of Ena.

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“…interacts with a wide variety of ligands and is involved in cell-ECM adhesion, cell differentiation and proliferation, and blood coagulation, and is an inhibitor of complement pathway(s) (Seiffert, 1997;Preissner and Seiffert, 1998). Two forms of vitronectin exist under physiological conditions, with most of the circulating pool of vitronectin in a native (monomeric) form (M r 75 kDa), whereas the multimeric form of vitronectin is found predominantly in the ECM or is tissue associated (Stockmann et al, 1993).…”

Section: Ingestion Of Pneumococci By Host Cells Via Vitronectin Requimentioning

confidence: 99%

Integrin-linked kinase is required for vitronectin-mediated internalization ofStreptococcus pneumoniaeby host cells

Bergmann

Lang

Rohde

et al. 2009

Journal of Cell Science

118

147

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By interacting with components of the human host, including extracellular matrix (ECM) proteins, Streptococcus pneumoniae has evolved various strategies for colonization. Here, we characterized the interaction of pneumococci with the adhesive glycoprotein vitronectin and the contribution of this protein to pneumococcal uptake by host cells in an integrin-dependent manner. Specific interaction of S. pneumoniae with the heparin-binding sites of purified multimeric vitronectin was demonstrated by flow cytometry analysis. Host-cell-bound vitronectin promoted pneumococcal adherence to and invasion into human epithelial and endothelial cells. Pneumococci were trapped by microspike-like structures, which were induced upon contact of pneumococci with host-cell-bound vitronectin. αvβ3 integrin was identified as the major cellular receptor for vitronectin-mediated adherence and uptake of pneumococci. Ingestion of pneumococci by host cells via vitronectin required a dynamic actin cytoskeleton and was dependent on integrin-linked kinase (ILK), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (Akt), as demonstrated by gene silencing or in inhibition experiments. In conclusion, pneumococci exploit the vitronectin–αvβ3-integrin complex as a cellular receptor for invasion and this integrin-mediated internalization requires the cooperation between the host signalling molecules ILK, PI3K and Akt.

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The Glycosaminoglycan Binding Site Governs Ligand Binding to the Somatomedin B Domain of Vitronectin

Cited by 30 publications

References 31 publications

Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces

Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces

Mutations inDrosophilaEnabled and Rescue by Human Vasodilator-stimulated Phosphoprotein (VASP) Indicate Important Functional Roles for Ena/VASP Homology Domain 1 (EVH1) and EVH2 Domains

Integrin-linked kinase is required for vitronectin-mediated internalization ofStreptococcus pneumoniaeby host cells

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The Glycosaminoglycan Binding Site Governs Ligand Binding to the Somatomedin B Domain of Vitronectin

Cited by 30 publications

References 31 publications

Maintenance of CD34 Expression During Proliferation of CD34 + Cord Blood Cells on Glycosaminoglycan Surfaces

Maintenance of CD34 Expression During Proliferation of CD34 + Cord Blood Cells on Glycosaminoglycan Surfaces

Mutations inDrosophilaEnabled and Rescue by Human Vasodilator-stimulated Phosphoprotein (VASP) Indicate Important Functional Roles for Ena/VASP Homology Domain 1 (EVH1) and EVH2 Domains

Integrin-linked kinase is required for vitronectin-mediated internalization ofStreptococcus pneumoniaeby host cells

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Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces

Maintenance of CD34 Expression During Proliferation of CD34 ⁺ Cord Blood Cells on Glycosaminoglycan Surfaces