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PubMed1993

Modulation of vitronectin receptor-mediated osteoclast adhesion by Arg-Gly-Asp peptide analogs: a structure-function analysis.

This study details the investigation of induction of retractile shape change in the osteoclast through inhibition of adhesion between osteoclasts and matrix with (1) peptide analogs bearing an Arg-Gly-Asp (RGD) sequence, (2) antibodies to the integrin alpha V beta 3 vitronectin receptor, and (3) the RGD-containing snake venom peptide echistatin. Osteoclast retraction on dentin has been demonstrated for GRGDSP peptide, in contrast to the inactivity of the analog containing the conservative RGE sequence modification. An osteoclast adhesion assay employing rat or chick bone cells and serum-coated glass coverslips as substrate was developed for routine evaluation of inhibition of adhesion. Antibodies F4 and F11 to the beta 3 chain of rat vitronectin receptor were effective at submicromolar concentrations in rat osteoclasts (IC50 0.29 and 0.05 microM, respectively), whereas MAb 23C6 to human/chick vitronectin receptor was somewhat less effective against chick osteoclasts (IC50 1.6 microM). A rank order of RGD analog activity (mean IC50, microM) in the serum-coated glass adhesion assay was derived for the linear peptides GRGDSP (201 microM), GRGDTP (180 microM), Ac-RGDS-NH2 (84 microM), Ac-RGDV-NH2 (68 microM), RGDV (43 microM), GRGDS (38 microM), and RGDS (26 microM). The two most potent short peptides were the cyclic analog SK&F 106760 Ac-S,S-cyclo-(Cys-(N alpha Me)Arg-Gly-Asp-Pen)-NH2 (IC50 7.0 microM), and the Telios peptide H-Gly-S,S-cyclo-(Pen-Gly-Arg-Gly-Asp-Ser-Pro-Cys)-Ala-OH (IC50 6.6 microM). The snake venom peptide echistatin was the most potent substance evaluated in the serum-coated glass assay (IC50 0.78 nM) employing either rat or chick osteoclasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Involvement of vitronectin and of a natural extracellular matrix in prostatic cell to cell contact and interaction with the substratum in culture.

The kinetics and regulation of attachment, the spreading and initial growth of canine prostatic epithelial cells in primary monolayers, as well as the ability of the cells to produce a natural extracellular matrix (nECM) have been studied. Within 1 day of culture, attachment without spreading occurred in uncoated dishes while spreading was observed in nECM-coated dishes. The attachment was stimulated by dialyzed fetal bovine serum (dFBS) and/or by the nECM and was not affected by the presence of cycloheximide at 10(-6) M. This effect of dFBS on attachment was maximal at a concentration of 10% and increased with cell density and was mainly attributed to vitronectin as demonstrated by gel filtration, selective adsorption of serum proteins to the substratum, and indirect immunofluorescence of prostatic epithelial cells incubated with a rabbit antiserum against bovine vitronectin. Dog serum reduced attachment while bovine serum albumin, phenol red, and steroids were inactive. The maximal effect of the nECM on attachment was observed with matrices produced by canine prostatic epithelial cells cultured in the presence of dog serum for more than 10 days. As revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, several proteins of relative mass (Mr) of 210, 113, 61, 56, 52, 49, 45, and 42 kDa remained in the dish following nECM denudation and could be responsible for its effect on attachment. Their deposition as well as intercell adhesion and cell-to-substratum interactions required an active protein synthesis plus non-steroidal serum components. Once attached and spread in primary monolayers, prostatic epithelial cells divided by the 3rd to 4th day; their growth, stimulated by dFBS at an optimal concentration of 20%, was inhibited by cycloheximide while the nECM was inactive. Thus, vitronectin in serum and the nECM synthesized by canine prostatic epithelial cells are responsible for the attachment and spreading of homologous cells to an in vitro substratum; nECM proteins also contribute to cell-to-cell contact and cell-to-substratum interaction in the monolayers.

Animals↗
PubMed2001

The poliovirus receptor CD155 mediates cell-to-matrix contacts by specifically binding to vitronectin.

The human receptor for poliovirus (CD155) is an immunoglobulin-like molecule with unknown normal function(s). Here we provide evidence that CD155 binds specifically to vitronectin with a dissociation constant (K(d)) of 72 nM as determined by surface plasmon resonance. Based on sequence homology to the CD155 gene, three poliovirus receptor-related genes (PRR1, PRR2, and PRR3) were cloned recently. PRR proteins were reported by others to mediate homophilic cell adhesion. Neither PRR1 nor PRR2 binds poliovirus and it is assumed that their physiological functions differ from that of CD155. Indeed, mPRR2 was found to bind to vitronectin only weakly, while its self-adhesion activity is characterized by a K(d) of 310 nM. Moreover, there is no evidence for CD155 self-adhesion. Both CD155 and vitronectin colocalize to follicular dendritic cells and B cells inside the germinal centers of secondary lymphoid tissue (tonsils)-an observation suggesting that the CD155/vitronectin interaction is required for the establishment of a proper immune response in this particular context.

Animals↗
PubMed1992

The human vitronectin (complement S-protein) gene maps to the centromeric region of 17q.

Vitronectin (complement S-protein, serum-spreading factor, epibolin) is a multifunctional glycoprotein that mediates cell-to-substrate adhesion, inhibits the cytolytic action of the terminal complement cascade in vitro and binds to several serine protease inhibitors of the serpin family, viz. antithrombin III, plasminogen activator inhibitor I (PAI-1) and II (PAI-2), heparin cofactor II and protease nexin. Using high resolution fluorescence in situ hybridization, we mapped the vitronectin gene to the centromeric region of the long arm of chromosome 17 corresponding to 17q11. The location was confirmed by co-hybridization with the centromere-specific alphoid probe p17H8 (D17Z1) and by chromosome banding with 4,6-diamidino-2-phenylindole-dihydrochloride (DAPI). None of the previously mapped genes that are evolutionary related to vitronectin are located on the same chromosome.

Centromere↗
PubMed1994

Regulation of vitronectin receptor expression by retinoic acid on human melanoma cells.

The integrin family of adhesion receptors is likely to be important for tumor cell invasion and dissemination. We have studied the effects of the differentiating agents retinoic acid on integrin expression by the human melanoma cell line MeWo. Our results show that this agent inhibits cellular proliferation, increases melanin content and induces morphological changes in MeWo cells. Functionally, these alterations are associated with an enhanced adhesion to matrix protein vitronectin and higher levels of expression of vitronectin receptor on the cell surface. This is accompanied by increased levels of alpha v integrin mRNA. Although the mechanism by which retinoic acid regulates the expression of vitronectin receptor in MeWo cells needs further examination, this system may represent a good model for understanding the role of this receptor in melanoma progression, as well the molecular basis for retinoic acid therapy in these tumors.

Blotting, Northern↗
PubMed1992

Physarum vitronectin-like protein: an Arg-Gly-Asp-dependent cell-spreading protein with a distinct NH2-terminal sequence.

A 70-kDa protein cross-reacted with anti-bovine vitronectin was isolated from slime mold Physarum polycephalum. The NH2-terminal amino acid sequence of the protein, referred to as Physarum vitronectin-like protein, did not share any homology with those of animal vitronectins. It had cell-spreading activity, which was specifically inhibited by an Arg-Gly-Asp (RGD)-containing peptide.

Amino Acid Sequence↗
PubMed1993

Synthetic peptides derived from the sequence around the plasmin cleavage site in vitronectin. Use in mapping the PAI-1 binding site.

A series of 8 peptides derived from the amino acid sequence accommodating the plasmin cleavage site in vitronectin were synthesized and used to map its binding site for the type I plasminogen activator inhibitor (PAI-1). This mapping assigned the inhibitor binding site to the K348-R370 region with high affinity recognition elements within the K348-R357 sequence. These results account for our previous finding that cleavage of the R361-S362 bond by plasmin significantly reduces the affinity between PAI-1 and vitronectin, since it splits the PAI-1 binding site in two. Furthermore, in the case of the two-chain form of vitronectin, this cleavage detaches the S362-R379 peptide which provides some of the affinity elements for the binding of PAI-1.

Amino Acid Sequence↗
PubMed2000

Domain 1 of the urokinase receptor (uPAR) is required for uPAR-mediated cell binding to vitronectin.

In the present paper we have analyzed uPAR-mediated cellular binding to vitronectin using the murine erythroid progenitor cell line 32D. We show that expression of uPAR in 32D cells promotes cellular binding to vitronectin, but fails to support cell spreading. The strength of binding is correlated to the expression level of uPAR and is strongly stimulated by the presence of uPAR ligands. Using a truncated variant of uPAR lacking domain 1 and by antibody inhibition experiments, we demonstrate that domain 1 plays a crucial role in uPAR-mediated cellular binding. The failure of the mutant uPAR to promote cellular binding is paralleled by a strong reduction in the affinity for vitronectin in vitro.

Animals↗
PubMed2002

The vitronectin binding area of plasminogen activator inhibitor-1, mapped by mutagenesis and protection against an inactivating organochemical ligand.

A distinguishing feature of serpins is their ability to undergo a conformational change consisting in insertion of the reactive centre loop (RCL) into beta-sheet A. In the serpin plasminogen activator inhibitor-1 (PAI-1), RCL movements are regulated by vitronectin, having a previously poorly defined binding site lateral to PAI-1's beta-sheet A. Using a novel strategy, based on identification of amino acid residues necessary for vitronectin protection of PAI-1 against inactivation by 4,4'-dianilino-1,1'-bisnaphthyl-5,5'-disulfonic acid, we have defined a vitronectin binding surface spanning 10 residues between alpha-helix F, beta-strand 2A, and alpha-helix E. Our results contribute to elucidating the unique serpin conformational change.

Amino Acid Sequence↗
PubMed2000

The effect of adsorbed fibrinogen, fibronectin, von Willebrand factor and vitronectin on the procoagulant state of adherent platelets.

Procoagulant (activated) platelets provide a site for assembly of the prothrombinase complex which can rapidly convert prothrombin into thrombin (a potent inducer of clot formation). Previously, we reported that adhesion of platelets to surfaces preadsorbed with blood plasma caused them to become procoagulant. In the present study we investigated the effect of adsorbed adhesion proteins (fibrinogen (Fg), fibronectin (Fn), von Willebrand factor (vWF) and vitronectin (Vn)) on the procoagulant activity of adherent platelets. Adsorbed Fn, vWF and Fg promoted platelet adhesion in the following order: Fn < vWF = Fg. However, these proteins promoted platelet activation (thrombin generation per adherent platelet) in the following order: Fg < Fn < vWF. Adsorption with a series of dilutions of normal plasma, serum, and plasmas deficient in or depleted of von Willebrand factor (de-vWF), fibronectin (de-Fn), vitronectin (de-Vn), or both vitronectin and fibronectin (de-VnFn) resulted in varied platelet adhesion, but little difference in platelet activation. However, preadsorption with dilute de-vWF plasma induced lower procoagulant activity than normal plasma. Preadsorption with normal plasma resulted in higher levels of platelet activation than preadsorption with Fg, suggesting that adsorption of plasma proteins other than Fg caused the high levels of activation observed for plasma preadsorbed surfaces.

Adsorption↗
PubMed1996

The inhibition of human factor Xa by plasminogen activator inhibitor type 1 in the presence of calcium ion, and its enhancement by heparin and vitronectin.

Plasminogen activator inhibitor type 1 (PAI-1), a member of serine proteinase inhibitor superfamily, is known to inhibit thrombin in the presence of either heparin or vitronectin. We analyzed possible inhibitory activity of PAI-1 on human factor Xa. PAI-1 inhibited factor Xa in the presence of calcium ion (Ca2+), whereas no inhibition was observed in the absence of Ca2+. Half maximal enhancement by Ca2+ was obtained at 0.8 mM. An equimolar complex formation between factor Xa and PAI-1 in the presence of Ca2+ was observed by SDS polyacrylamide gel electrophoresis. Both unfractionated heparin and vitronectin enhanced the inhibition only in the presence of Ca2+. Apparent second-order rate constant (ki) for the inhibition of factor Xa by PAI-1 at 5 mM Ca2+ was 1.6 x 10(4) M-1 s-1, and was enhanced 3-fold by 2 u/ml of heparin (4.6 x 10(4) M-1 s-1) and 10-fold by 100 nM vitronectin (1.6 x 10(5) M-1 s-1), respectively. The interaction between Ca(2+)-bound factor Xa and PAI-1 could be important from the view of PAI-1 neutralization and enhancement of fibrinolysis.

Calcium↗
PubMed2003

Galectin 1 inhibits incorporation of vitronectin and chondroitin sulfate B into the extracellular matrix of human vascular smooth muscle cells.

Galectin-1, a beta-galactoside-binding dimeric lectin, interacts with the extracellular matrix (ECM) of smooth muscle cells (SMCs) and with particular ECM proteins. Enrichment of the ECM with galectin-1 affects adhesion and proliferation of cultured SMCs. Here we investigated whether galectin-1 (1) interacts with glycosaminoglycan (GAG) chains, (2) cross-links between ligands and facilitates the incorporation of GAGs, vitronectin and plasma fibronectin in the ECM of vascular SMCs. A recombinant galectin-1 fusion protein GalH, used in this study, formed dimers and interacted with ECM proteins. GAG chains inhibited these interactions. Among the studied GAG chains, only chondroitin sulfate B interacted with GalH in beta-galactoside-dependent manner. GalH did not bridge between ECM proteins on solid phase and [125I]-labelled ECM proteins or GAGs in solution. The ECM incorporated less vitronectin in the presence of soluble GalH. GalH-enriched ECM incorporated less vitronectin and chondroitin sulfate B. The ECM partially depleted of endogenous galectins incorporated more chondroitin sulfate B compared to untreated ECM. These results suggest that galectin-1 is likely to be involved in the ECM assembly affecting incorporation of some ECM components important for SMC behaviour.

Cells, Cultured↗
PubMed1996

A recombinant, arginine-glycine-aspartic acid (RGD) motif from foot-and-mouth disease virus binds mammalian cells through vitronectin and, to a lower extent, fibronectin receptors.

The cell-binding abilities of a recombinant, RGD-containing peptide from foot-and-mouth disease virus (FMDV) have been characterized in HeLa and BHK cells. This peptide represents the aa sequence of the solvent-exposed G-H loop of protein VP1 which is involved in cell recognition and infection. The efficiency of the viral motif in promoting cell attachment and spreading is comparable to that shown by fibronectin or vitronectin. Cell binding is inhibited by a monoclonal antibody directed against a viral, RGD-involving B-cell epitope and also by sera against vitronectin (alpha V beta 3/beta 5) and fibronectin (alpha 5 beta 1) receptors. In addition, a synthetic RGD peptide, which is a ligand for both integrins, prevents the cell binding mediated by the FMDV domain. These data demonstrate that the FMDV RGD motif is a potent ligand for cell-receptor integrins and sufficient to promote cell attachment to susceptible cells mainly through the vitronectin receptor.

Amino Acid Sequence↗
PubMed2000

Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections.

PURPOSE: To evaluate fibronectin, vitronectin, laminin, and collagen type IV adhesion to poly(methyl methacrylate) (PMMA), silicone, hydrophobic soft acrylate, and hydrogel intraocular lenses (IOLs) in pseudophakic human autopsy eyes. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Thirty-eight autopsy eyes containing PMMA, silicone, hydrophobic acrylate, or hydrogel IOLs were assessed. Histological sections were prepared from each eye, and immunohistochemical analyses were performed for fibronectin, vitronectin, laminin, and collagen type IV. One hundred fifty-two specimens were analyzed. RESULTS: A sandwich-like structure (anterior or posterior capsule/fibronectin/1 cell layer/fibronectin/IOL surface) was seen in 12 of 14 autopsy eyes with soft acrylate IOLs, 3 of 10 with a PMMA IOL (P =.0094), 1 of 10 with a silicone IOL (P =.0022), and 0 of 4 with a hydrogel IOL (P =. 0041). The thicker fibrocellular tissue on the inner surface of the anterior or posterior capsule that was in contact with silicone IOLs was lined with collagen type IV. Vitronectin and laminin were not found at the fibrocellular tissue-IOL interface in any specimen. CONCLUSIONS: This study seems to confirm the sandwich theory of posterior capsule opacification in eyes with an IOL and suggests that fibronectin may be the major extracellular protein responsible for the attachment of hydrophobic soft acrylate (AcrySof(R)) IOLs to the capsular bag. This may represent a true bioactive bond between the IOL and lens epithelial cells or between the IOL and the capsular bag and may be one reason the PCO and neodymium:YAG capsulotomy rates are lower in eyes with a soft acrylate IOL.

Biocompatible Materials↗
PubMed2003

Adhesion of soluble fibronectin, vitronectin, and collagen type IV to intraocular lens materials.

PURPOSE: To evaluate soluble fibronectin, vitronectin, and collagen type IV adhesion to poly(methyl methacrylate) (PMMA), fluorine-surface-modified PMMA, silicone, hydrophobic and hydrophilic acrylate, and hydrogel intraocular lenses (IOLs) and determine whether hydrophobic and hydrophilic acrylate materials have different fibronectin-adhesion properties. SETTING: Department of Medical Biochemistry, University of Oulu, Oulu, Finland. METHODS: One hundred fifty IOLs were incubated for 1 week at 37 degrees C with radioactive-iodine-labeled soluble fibronectin, vitronectin, or collagen type IV. Fifty IOLs were analyzed for each protein, 5 from each of 10 different IOL models (PMMA, Alcon MC60BM; fluorine-surface-modified PMMA, Chiron Fluorilens Centra-55F; silicone, Allergan Medical Optics SI-40NB and Pharmacia and Upjohn CeeOn 911A; hydrophobic soft acrylate, Alcon AcrySof MA60BM and SA30AL and AMO Sensar; hydrophilic soft acrylate, Ioltech Stabibag and Bausch and Lomb BL27; and hydrogel, Bausch and Lomb Hydroview. The amount of adherent protein was measured with a gamma counter at 1 and 7 days and expressed as counts per minute. RESULTS: At 1 week, significantly more fibronectin was bound to the hydrophobic acrylate IOLs than to the 2-hydroxyethyl methacrylate (HEMA) containing hydrophilic acrylate IOLs (P <.05 to.0001). Significantly more vitronectin was bound to the 2 silicone IOLs than to any other IOL (P <.01 to.0001) at 7 days. Collagen type IV adhered best to the hydrophilic acrylate IOLs, which were significantly different (P <.01 to.0001) than the other IOLs at 1 and 7 days. CONCLUSIONS: Each IOL material had a different affinity to each protein. Significant binding to 1 protein does not indicate that the IOL will bind significantly to all proteins; instead, each protein should be studied separately. Fibronectin bound significantly better to hydrophobic acrylate IOLs than to hydrophilic acrylate IOLs, suggesting that the HEMA-containing IOLs should be classified with the hydrogel IOL group.

Adhesiveness↗
PubMed1990

Fibronectin, vitronectin, and collagen binding to Escherichia coli of intestinal and extraintestinal origin.

Strains of enteropathogenic Escherichia coli (EPEC, 157 strains), enterotoxigenic E. coli (ETEC, 10 strains), enteroinvasive E. coli (EIEC, 40 strains), enterohaemorrhagic E. coli (EHEC, 10 strains), and enteroadherent E. coli (EAEC, 6 strains), all isolated from children and adults with diarrhoea, uropathogenic E. coli (25 strains) and faecal E. coli (36 strains) isolated from healthy persons were tested for binding to subepithelial connective tissue proteins, viz. fibronectin, collagen and vitronectin (S-protein). Strains expressing high and moderate binding to these proteins were found in all groups including normal stools. The highest incidence of binding strains were found among EAEC, EHEC and EPEC strains. Many strains bound collagen only whereas no strain bound vitronectin only. Binding to these proteins was generally best expressed after overnight growth on CFA agar at 37 degrees C. It is not correlated to surface hydrophobicity, and it is not influenced by O antigens or K1 and K5 antigens. The presence of fimbrial adhesins on extraintestinal isolates did not enhance the binding to soluble form of the matrix proteins. During pathological conditions when subepithelial connective tissue proteins are exposed, strains with the ability to bind fibronectin, collagen and/or vitronectin may have a selective advantage to colonize the tissue.

Bacterial Adhesion↗
PubMedDate not supplied

Immunolocalization of elastin, collagen type I and type III, fibronectin, and vitronectin in extracellular matrix components of normal and myxomatous mitral heart valve chordae tendineae.

The identification, distribution, and localization of matrix proteins and the proteins associated with normal and degenerated elastic fibers and collagen fibrils of myxomatous chordae tendineae were studied with immunoelectron microscopy. Ultrathin sections of L R White-embedded tissue were processed by indirect immunogold cytochemistry using primary antibodies against human alpha elastin, collagen types I and III, fibronectin, and vitronectin. In normal chordae tendineae, alpha elastin antibody heavily labeled the elastic fibers in spongiosa and fibrosa, but microfibrils around them were not labeled. Antibodies to collagen type I, collagen type III, and fibronectin all labeled the collagen fibers and microfibrils in the spongiosa. Fibronectin antibody labeling was higher than collagen type III, whereas labeling by anticollagen type I was lower. Intense labeling by vitronectin was observed on the microfibrils in the spongiosa and on electron-dense material around elastic fibers in the spongiosa and fibrosa. In myxomatous chordae tendineae, alpha elastin antibody heavily labeled degenerated elastic fibers, previously unidentified reticulated structures, and other moderately electron-dense material, both in the spongiosa and in the fibrosa, but not the electron-dense fibrous material around them. Antibodies to collagen types I, III, and fibronectin heavy labeled electron-dense aggregates of fibrous material. Vitronectin labeling was observed on electron-dense longitudinally running microfibrils and on the electron-dense microfibrils around degenerated elastic fibers.

Aged↗
PubMed2005

A model for the three-dimensional structure of human plasma vitronectin from small-angle scattering measurements.

Small-angle X-ray scattering (SAXS) measurements were used to characterize vitronectin, a circulatory protein found in human plasma that functions in regulating cell adhesion and migration, as well as proteolytic cascades that affect blood coagulation, fibrinolysis, and pericellular proteolysis. SAXS measurements were taken over a 3-fold range of protein concentrations, yielding data that characterize a monodisperse system of particles with an average radius of gyration of 30.3 +/- 0.6 A and a maximum linear dimension of 110 A. Shape restoration was applied to the data to produce two models of the solution structure of the ligand-free protein. A low-resolution model of the protein was generated that indicates the protein to be roughly peanut-shaped. A better understanding of the domain structure of vitronectin resulted from low-resolution models developed from available high-resolution structures of the domains. These domains include the N-terminal domain that was determined experimentally by NMR [Mayasundari, A., Whittemore, N. A., Serpersu, E. H., and Peterson, C. B. (2004) J. Biol. Chem. 279, 29359-29366] and the docked structure of the central and C-terminal domains that were determined by computational threading [Xu, D., Baburaj, K., Peterson, C. B., and Xu, Y. (2001) Proteins: Struct., Funct., Genet. 44, 312-320]. This model provides an indication of the disposition of the central domain and C-terminal heparin-binding domains of vitronectin with respect to the N-terminal somatomedin B (SMB) domain. This model constructed from the available domain structures, which agrees with the low-resolution model produced from the SAXS data, shows the SMB domain well separated from the central and heparin-binding domains by a disordered linker (residues 54-130). Also, binding sites within the SMB domain are predicted to be well exposed to the surrounding solvent for ease of access to its various ligands.

Computational Biology↗