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E Ruoslahti

Publications and source records attributed to E Ruoslahti.

At least 91 records · Page 5Linked to original sources
PubMed1995

Vascular smooth muscle cells from injured rat aortas display elevated matrix production associated with transforming growth factor-beta activity.

The arterial response to injury is characterized by a short period of increased proliferation and migration of vascular smooth muscle cells, followed by an extended period of extracellular matrix accumulation in the intima. Transforming growth factor-beta (TGF-beta) has been implicated as a causative factor in the formation of extracellular matrix in this process, which leads to progressive thickening of the intima, known as intimal hyperplasia. In vitro analysis of vascular smooth muscle cells harvested from normal rat aortas and from aortas injured 14 days earlier showed that both types of cells attached equally well to culture dishes but that the initial spreading of the cells was increased in cells derived from injured vessels. Cells from the injured arteries produced more fibronectin and proteoglycans into the culture medium than the cells from normal arteries and contained more TGF-beta 1 mRNA. TGF-beta 1 increased proteoglycan synthesis by normal smooth muscle cells, and the presence of a neutralizing anti-TGF-beta 1 antibody reduced proteoglycan synthesis by the cells from injured arteries in culture. Fibronectin synthesis was not altered by these treatments. These results indicate that the accumulation of extracellular matrix components in neointimal lesions is at least partially caused by autocrine TGF-beta activity in vascular smooth muscle cells.

Animals↗
PubMed1994

Association of insulin receptor substrate-1 with integrins.

Insulin stimulation was found to promote association of the alpha v beta 3 integrin (a vitronectin receptor) with insulin receptor substrate-1 (IRS-1), an intracellular protein that mediates insulin signaling by binding other signaling molecules, including growth factor receptor-bound protein 2 (Grb2) and phosphatidylinositol-3' kinase. Insulin-treated cells expressing the alpha v beta 3 integrin showed 2.5 times more DNA synthesis when plated on vitronectin than on other substrates, whereas cells expressing another vitronectin receptor, alpha v beta 5, did not show this difference. The association between integrin and IRS-1 may be a mechanism for the synergistic action of growth factor and extracellular matrix receptors.

Amino Acid Sequence↗
PubMed1994

Interaction of the small interstitial proteoglycans biglycan, decorin and fibromodulin with transforming growth factor beta.

We have analysed the interactions of three proteoglycans of the decorin family, decorin, biglycan and fibromodulin, with transforming growth factor beta (TGF-beta). The proteoglycan core proteins, expressed from human cDNAs as fusion proteins with Escherichia coli maltose-binding protein, each bound TGF-beta 1. They showed only negligible binding to several other growth factors. Intact decorin, biglycan and fibromodulin isolated from bovine tissues competed with the fusion proteins for the TGF-beta binding. Affinity measurements suggest a two-site binding model with Kd values ranging from 1 to 20 nM for a high-affinity binding site and 50 to 200 nM for the lower-affinity binding site. The stoichiometry indicated that the high-affinity binding site was present in one of ten proteoglycan core molecules and that each molecule contained a low-affinity binding site. Tissue-derived biglycan and decorin were less effective competitors for TGF-beta binding than fibromodulin or the non-glycosylated fusion proteins; removal of the chondroitin/dermatan sulphate chains of decorin and biglycan (fibromodulin is a keratan sulphate proteoglycan) increased the activities of decorin and biglycan, suggesting that the glycosaminoglycan chains may hinder the interaction of the core proteins with TGF-beta. The fusion proteins competed for the binding of radiolabelled TGF-beta to Mv 1 Lu cells and endothelial cells. Affinity labelling showed that the binding of TGF-beta to betaglycan and the type-I receptors in Mv 1 Lu cells and to endoglin in endothelial cells was reduced, but the binding to the type-II receptors was unaffected. TGF-beta 2 and 3 also bound to all three fusion proteins. Latent recombinant TGF-beta 1 precursor bound slightly to fibromodulin and not at all to decorin and biglycan. The results show that the three decorin-type proteoglycans each bind TGF-beta isoforms and that slight differences exist in their binding properties. They may regulate TGF-beta activities by sequestering TGF-beta into extracellular matrix.

Biglycan↗
PubMed1994

Identification of Gal(beta 1-3)GalNAc bearing glycoproteins at the nodes of Ranvier in peripheral nerve.

A subset of human anti-GM1 ganglioside antibodies cross-reacts with Gal(beta 1-3)GalNAc bearing glycoproteins in peripheral nerve and spinal cord. The same oligosaccharide determinant is recognized by the lectin peanut agglutinin (PNA) which binds at the nodes of Ranvier in intact peripheral nerve. The Gal(beta 1-3)GalNAc bearing glycoproteins were isolated using PNA lectin affinity chromatography followed by separation on Western blot, and the proteins were subjected to partial amino acid sequence analysis. Two major PNA binding glycoproteins were identified in peripheral nerve and spinal cord; one had an approximate molecular weight of 120 kD and had sequence homology to the oligodendrocyte-myelin glycoprotein (OMgp). The other migrated between 70 and 80 kD and had sequence homology to the hyaluronate binding domain of versican, which has been reported to share sequence homology with the 70 kD proteins hyaluronectin and the glial hyaluronic acid binding protein (GHAP). By immunocytochemistry, OMgp was localized to the paranodal region of myelin, and the protein homologous to the hyaluronate binding domain of versican was localized to the nodal gap in peripheral nerve. These PNA binding glycoproteins might be target antigens for autoantibodies in peripheral nerve.

Amino Acid Sequence↗
PubMed1994

Crystals of the cell-binding module of fibronectin obtained from a series of recombinant fragments differing in length.

A recombinant fragment corresponding to the cell adhesion module (FNIII10) of human fibronectin has been crystallized at pH 8.6 from solutions containing polyethylene glycol as precipitant. The crystals formed in the space group P2(1) with a = 30.76 A, b = 35.07 A, c = 37.66 A, beta = 106.9 degrees. There is one molecule per asymmetric unit and the crystals diffract beyond 1.75 A resolution. To improve the prospects for successful crystallization of the FNIII10 module, a series of recombinant fragments was produced with minor differences in the length of N or C-terminal segments. Only one of these variants crystallized. Interestingly, the C-terminal residue of this variant formed stable intermolecular contacts with a symmetry-related molecule in the crystal lattice.

Amino Acid Sequence↗
PubMed1994

Crystal structure of the tenth type III cell adhesion module of human fibronectin.

The crystal structure of the cell adhesion module of fibronectin (FNIII10) has been determined at 1.8 A resolution. A recombinant fragment corresponding to the tenth type III module of human fibronectin was crystallized in space group P2(1) with a = 30.7, b = 35.1 and c = 37.7 A and beta = 107 degrees. The structure was determined by molecular replacement and refined by least squares methods. The crystallographic R-factor for the final model of the 91 amino acid module plus 56 solvent atoms is 0.18 for 10 to 1.8 A data. The module consists of two layers of beta-sheet, one with three antiparallel strands and the other with four antiparallel strands. The beta-sheets enclose a hydrophobic core of 24 amino acid side-chains. The module contains the RGD cell recognition sequence in a flexible loop connecting two beta-strands. The tertiary structure of the FNIII10 module has been used to develop a structure-based sequence alignment of 17 type III modules in fibronectin based on the striking conservation of homologous hydrophobic residues. A similar pattern of homologous alternating hydrophobic residues is also evident in a comparison of type III modules in proteins unrelated to fibronectin such as cytokine receptors and muscle proteins.

Amino Acid Sequence↗
PubMed1994

BR140, a novel zinc-finger protein with homology to the TAF250 subunit of TFIID.

The Br140 protein was initially identified due to its co-purification with an integrin. We have cloned and sequenced the cDNA corresponding to the Br140 protein. Analysis of the amino acid sequence indicates that Br140 has features characteristic of gene regulatory proteins, including zinc fingers. Furthermore, Br140 has a homology to a family of transcriptional co-activators, one of which is a characterized component of the general transcriptional machinery. Immunologic studies indicate that Br140 has a broad tissue distribution and is abundant in testes and spermatogonia. Br140 is primarily a nuclear protein. These results suggest that Br140 may be a part of the general transcriptional machinery.

Adaptor Proteins, Signal Transducing↗
PubMed1994

Superfibronectin is a functionally distinct form of fibronectin.

Fibronectin is an extracellular matrix protein that is important in development, wound healing and tumorigenesis. In the blood it is dimeric, but in tissues forms disulphide crosslinked fibrils. Here we show that a fragment from the first type-III repeat of fibronectin binds to fibronectin and induces spontaneous disulphide crosslinking of the molecule into multimers of high relative molecular mass which resemble matrix fibrils. Treatment of fibronectin with this inducing fragment also converts fibronectin into a form that has greatly enhanced adhesive properties (hence the term superfibronectin) and which suppresses cell migration. Whereas cells attach to fibronectin through integrins, cell attachment to superfibronectin is mediated both by integrins and by receptors with properties distinct from those of integrins. Superfibronectin may be closely related to the natural matrix form of fibronectin.

Amino Acid Sequence↗
PubMed1994

Isolation of a highly specific ligand for the alpha 5 beta 1 integrin from a phage display library.

Our previous studies showed that the alpha 5 beta 1 integrin selects cysteine pair-containing RGD peptides from a phage display library based on a random hexapeptide. We have therefore searched for more selective peptides for this integrin using a larger phage display library, where heptapeptides are flanked by cysteine residues, thus making the inserts potentially cyclic. Most of the phage sequences that bound to alpha 5 beta 1 (69 of 125) contained the RGD motif. Some of the heptapeptides contained an NGR motif. As the NGR sequence occurs in the cell-binding region of the fibronectin molecule, this sequence could contribute to the specific recognition of fibronectin by alpha 5 beta 1. Selection for high affinity peptides for alpha 5 beta 1 surprisingly yielded a sequence RRETAWA that does not bear obvious resemblance to known integrin ligand sequences. The synthetic cyclic peptide GACRRETAWACGA (*CRRETAWAC*) was a potent inhibitor of alpha 5 beta 1-mediated cell attachment to fibronectin. This peptide is nearly specific for the alpha 5 beta 1 integrin, because much higher concentrations were needed to inhibit the alpha v beta 1 integrin, and there was no effect on alpha v beta 3- and alpha v beta 5-mediated cell attachment to vitronectin. The peptide also did not bind to the alpha IIb beta 3 integrin. *CRRETAWAC* appears to interact with the same or an overlapping binding site in alpha 5 beta 1 as RGD, because cell attachment to *CRRETAWAC* coated on plastic was divalent cation dependent and could be blocked by an RGD-containing peptide. These results reveal a novel binding specificity in the alpha 5 beta 1 integrin.

Amino Acid Sequence↗
PubMed1994

Altered localization and cytoplasmic domain-binding properties of tyrosine-phosphorylated beta 1 integrin.

We describe a novel approach to study tyrosine-phosphorylated (PY) integrins in cells transformed by virally encoded tyrosine kinases. We have synthesized a peptide (PY beta 1 peptide) that represents a portion of the cytoplasmic domain of the beta 1 integrin subunit and is phosphorylated on the tyrosine residue known to be the target of oncogenic tyrosine kinases. Antibodies prepared against the PY beta 1 peptide, after removal of cross-reacting antibodies by absorption and affinity purification, recognized the PY beta 1 peptide and the tyrosine-phosphorylated form of the intact beta 1 subunit, but did not bind the nonphosphorylated beta 1 peptide, the nonphosphorylated beta 1 subunit or other unrelated tyrosine-phosphorylated proteins. The anti-PY beta 1 antibodies labeled the podosomes of Rous sarcoma virus-transformed fibroblasts, but did not detectably stain nontransformed fibroblasts. The localization of the tyrosine phosphorylated beta 1 subunits appeared distinct from that of the beta 1 subunit. Adhesion plaques were stained by the anti-beta 1 subunit antibodies in Rous sarcoma virus-transformed fibroblasts plated on fibronectin, whereas neither podosomes nor adhesion plaques were labeled on vitronectin or on uncoated plates. Anti-phosphotyrosine antibodies labeled podosomes, adhesion plaques and cell-cell boundaries regardless of the substratum. One of the SH2 domains of the p85 subunit of phosphatidylinositol-3-kinase bound to the PY beta 1 peptide, but not to the non-phosphorylated beta 1 cytoplasmic peptide. Other SH2 domains did not bind to the PY beta 1 peptide. These results show that the phosphorylated form of the beta 1 integrin subunit is detected in a different subcellular localization than the nonphosphorylated form and suggest that the phosphorylation on tyrosine of the beta 1 subunit cytoplasmic domain may affect cellular signaling pathways.

3T3 Cells↗
PubMed1994

Antibodies against transforming growth factor-beta 1 suppress intimal hyperplasia in a rat model.

Intimal hyperplasia is induced by therapeutic vascular interventions and often results in clinically important narrowing of the vascular lumen. Examination of the role of TGF-beta 1 in a rat carotid artery injury model confirmed the presence of a previously reported increase in TGF-beta 1 mRNA in the media of injured arteries. Administration of neutralizing anti- TGF-beta 1 antibodies significantly (P < 0.05) reduced the size of the intimal lesions that developed after carotid balloon injury. A control antibody had no effect. The intimal/medial area ratio was also reduced in the anti-TGF-beta 1 group relative to controls (P < 0.01). Immunohistochemical staining showed that two TGF-beta 1-induced extracellular matrix components, EDA + fibronectin and versican, were greatly increased in the untreated neointimal lesions, but were almost completely absent from the lesions of the anti-TGF-beta 1-treated animals. We conclude that TGF-beta 1 is causally involved in the development of intimal hyperplasia, and that anti-TGF-beta 1 agents may be useful in achieving at least partial control of this condition.

Animals↗
PubMed1994

Integrins.

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Amino Acid Sequence↗
PubMed1994

Cell adhesion and tumor metastasis.

Integrins, among the various classes of cell adhesion receptors, are particularly associated with cell adhesion to extracellular matrices. They are heterodimeric transmembrane proteins with large ectodomains and short cytoplasmic tails. In many cases the sequence recognized by the integrins in the extracellular matrix proteins is the tripeptide Arg-Gly-Asp (RGD). Short synthetic peptides containing this sequence can inhibit tumor cell invasion in vitro and tumor dissemination in vivo. Because the alpha 5 beta 1 integrin appears to be the target of the peptides in many types of tumors, we have used phage display libraries to analyze the specificity of alpha 5 beta 1 and have isolated potent and specific inhibitors for this integrin. Increased expression of the alpha 5 beta 1 integrin, which is a fibronectin receptor, can also suppress cell migration and tumor cell invasion. We suggest this effect may be mediated through increased deposition of fibronectin matrix around the cells, because we found that the fibrillar matrix fibronectin suppresses tumor cell migration. There is increasing evidence that signals are elicited by the binding of integrins to their target proteins. This possibility has generated a great deal of interest in the cytoplasmic molecules that might mediate the integrin-associated signaling. At least two kinases, a novel tyrosine kinase, focal adhesion kinase (fak), and protein kinase C (PKC), are activated by integrin-mediated cell attachment. Moreover, a phosphorylated 190 kDa protein-associated with the alpha v beta 3 integrin has been found Anchorage dependence of cells and the migration-promoting activity of cell adhesion molecules are likely to depend on signal transduction through such molecules.

Animals↗
PubMed1993

Localization of transforming growth factor beta binding site in betaglycan. Comparison with small extracellular matrix proteoglycans.

The most abundant binding molecule for transforming growth factor beta (TGF-beta) on many cell types is betaglycan, a transmembrane proteoglycan. To localize the binding site for TGF-beta in betaglycan, parts of the betaglycan extracellular portion were expressed as recombinant fusion proteins in bacteria and tested for their ability to compete for the binding of TGF-beta 1 to Hep G2 cells. One fragment encompassing 226 residues near the transmembrane domain (amino acids 543-769) (López-Casillas, F., Cheifetz, S., Doody, J., Andres, J. L., Lane, W. S., and Massagué, J. (1991) Cell 67, 785-795) was active, whereas fusion proteins representing the other parts of the betaglycan ectodomain were inactive. Affinity measurements revealed two classes of binding sites (Kd = 3.9 nM and Kd = 145 nM) for the active fusion protein. The binding of the betaglycan fusion protein to immobilized TGF-beta 1 was inhibited by fusion proteins representing the core proteins of the small interstitial proteoglycans decorin, biglycan and fibromodulin, each also known to bind TGF-beta. The effective concentrations of TGF-beta for binding to these other proteoglycans were similar to those required for binding to betaglycan, indicating similar affinities for the binding of proteoglycans and betaglycan. Affinity cross-linking showed that, at low concentrations, the betaglycan fragment enhanced the binding of TGF-beta to the type II receptor and to endogenous betaglycan but had no effect on the binding to type I receptor. At high concentrations, the TGF-beta binding fragment inhibited the binding of TGF-beta to all these receptors. The fragment enhanced the activity of TGF-beta in mink lung cell bioassay at all active concentrations. The results indicate that betaglycan and the decorin type proteoglycans all bind to the same or closely spaced sites in TGF-beta and compete with one another for the binding. In addition, betaglycan may cooperate with the type II receptor on TGF-beta binding.

Animals↗
PubMed1993

Activation of protein kinase C precedes alpha 5 beta 1 integrin-mediated cell spreading on fibronectin.

Increasing evidence indicates that the integrin family of cell adhesion receptors can transduce biochemical signals from the extracellular matrix to the cell interior to modulate cell behavior. We have investigated the role of protein kinase C in alpha 5 beta 1 integrin-mediated signal transduction in Chinese hamster ovary cells. Up-regulation of protein kinase C activity by phorbol esters was found to enhance cell adhesion, spreading, and migration on a fibronectin substrate, without affecting the cell surface expression or fibronectin binding of the alpha 5 beta 1 integrin, whereas inhibition of protein kinase C activity by calphostin C inhibited these functions as well in unstimulated cells. In addition, we observed that protein kinase C activity in the cell membrane fraction transiently increases preceding cell spreading on fibronectin, but not on polylysine, additionally implying a specific role of protein kinase C in alpha 5 beta 1 integrin-mediated spreading on fibronectin. Experiments with phorbol esters and calphostin C also suggested that protein kinase C activity is required for enhanced phosphorylation of the focal adhesion kinase, pp125fak, in cells plated on fibronectin. Protein kinase C-alpha was not, however, found to directly act on pp125fak, suggesting that other mechanisms are involved in this phenomenon.

Animals↗
PubMed1993

Selection of peptides binding to the alpha 5 beta 1 integrin from phage display library.

The alpha 5 beta 1 integrin binds fibronectin through the integrin recognition sequence Arg-Gly-Asp (RGD). We have used a 6-amino acid peptide library expressed on filamentous phage to identify peptide ligands for alpha 5 beta 1. We found that this integrin selectively binds RGD-containing peptides from the library. Of the 32 different sequences obtained, 28 had the RGD motif, 3 contained sequences related to RGD, and only 1 had a clearly different sequence. One of the RGD-containing phage encoded a potentially cyclic insert CRGDCL. The cyclic peptide GAC*RGDC*LGA (where * denotes cysteines forming a disulfide bond) was 10-fold more efficient than any of the linear RGD-containing hexapeptides in inhibiting the binding of RGD-expressing phage to alpha 5 beta 1 or the attachment of alpha 5 beta 1-expressing cells to fibronectin. This peptide also inhibited cell attachment mediated by the alpha v beta 1, alpha v beta 3, and alpha v beta 5 integrins with about 10-fold higher efficiency than linear GRGDSP. One peptide containing an RGD-related sequence, NGRAHA, was also found to inhibit phage attachment and cell adhesion, especially adhesion mediated by the alpha v beta 5 integrin. These results indicate that novel and high affinity ligands for integrins can be isolated from a random peptide library.

Amino Acid Sequence↗