scholarly journals Thrombospondin modulates alpha v beta 3 function through integrin-associated protein.

1996 ◽  
Vol 135 (2) ◽  
pp. 533-544 ◽  
Author(s):  
A G Gao ◽  
F P Lindberg ◽  
J M Dimitry ◽  
E J Brown ◽  
W A Frazier
Keyword(s):  
Tyrosine Kinases ◽  
Kinase Inhibitors ◽  
Cell Binding ◽  
Mutant Peptide ◽  
Gi Protein ◽  
A Cell ◽  
Carboxyl Terminal ◽  
Alpha V Beta 3 ◽  
Cell Binding Domain ◽  
Common Cell

Integrin-associated protein (IAP) is a receptor for the carboxyl-terminal "cell-binding domain" (CBD) of thrombospondin 1 (TS1). IAP associates with alpha v beta 3 integrin and mAbs against IAP inhibit certain integrin functions. Here we examine the effects of the TS1 CBD and 4N1K (KRFYVVMWKK), a cell-binding peptide derived from it, on the adhesion and spreading on vitronectin (VN) of C32 human melanoma cells which express IAP, alpha v beta 3, and alpha v beta 5. Cells adhere to VN at low surface densities via alpha v beta 5 and spread very slowly while adhesion to higher density VN involves both alpha v beta 5 and alpha v beta 3 and results in rapid spreading. Spreading of the cells, but not adhesion, on sparse VN coatings is markedly enhanced by the presence of soluble TS1, the recombinant CBD and 4N1K, but not the "mutant" peptide 4NGG, KRFYGGMWKK, which fails to bind IAP. This enhanced spreading is completely blocked by mAb LM609 against alpha v beta 3 and the anti-IAP mAb B6H12. Correlated with this enhanced spreading is increased tyrosine phosphorylation of focal adhesion kinase (FAK), paxillin, and a protein of ca. 90 kD. The enhanced spreading induced by TS1 and 4N1K and the constitutive spreading on higher density VN are both blocked by calphostin C (100 nM), wortmannin (10 nM), and tyrosine kinase inhibitors. In contrast, pertussis toxin specifically blocks only the TS1 stimulated spreading on low density VN, indicating that IAP exerts its effects on signal transduction via a heterotrimeric Gi protein acting upstream of a common cell spreading pathway which includes PI-3 kinase, PKC, and tyrosine kinases.

scholarly journals Mapping of a cell-binding domain in the cell adhesion molecule gp80 of Dictyostelium discoideum.

1988 ◽  
Vol 107 (5) ◽  
pp. 1835-1843 ◽  
Author(s):  
R K Kamboj ◽  
L M Wong ◽  
T Y Lam ◽  
C H Siu
Keyword(s):  
Cell Adhesion ◽  
Dictyostelium Discoideum ◽  
Fusion Proteins ◽  
Binding Activity ◽  
Binding Domain ◽  
Globular Domain ◽  
Cell Binding ◽  
Homophilic Interaction ◽  
A Cell ◽  
Cell Binding Domain

At the aggregation stage of Dictyostelium discoideum development, a cell surface glycoprotein of Mr 80,000 (gp80) has been found to mediate the EDTA-resistant type of cell-cell adhesion via homophilic interaction (Siu, C.-H., A. Cho, and A. H. C. Choi. 1987. J. Cell Biol. 105:2523-2533). To investigate the structure-function relationships of gp80, we have isolated full length cDNA clones for gp80 and determined the DNA sequence. The deduced structure of gp80 showed three major domains. An amino-terminal globular domain composed of the bulk of the protein is supported by a short stalk region, which is followed by a membrane anchor at the carboxy terminus. Structural analysis suggested that the cell-binding domain of gp80 resides within the globular domain near the amino terminus. To investigate the relationship of the cell-binding activity to this region of the polypeptide, three protein A/gp80 (PA80) gene fusions were constructed using the expression vector pRIT2T. These PA80 fusion proteins were assayed for their ability to bind to aggregation stage cells. Binding of 125I-labeled fusion proteins PA80I (containing the Val123 to Ile514 fragment of gp80) and PA80II (Val123 to Ala258) was dosage dependent and could be inhibited by precoating cells with the cell cohesion-blocking mAb 80L5C4. On the other hand, there was no appreciable binding of PA80III (Ile174 to Ile514) to cells. Reassociation of cells was significantly inhibited in the presence of PA80I or PA80II. In addition, 125I-labeled PA80II exhibited homophilic interaction with immobilized PA80I, PA80II, or gp80. The results of these studies lead to the mapping of a cell-binding domain in the region between Val123 and Leu173 of gp80 and provide direct evidence that the cell-binding activity of gp80 resides in the protein moiety.

scholarly journals Bacteriophage Tuc2009 Encodes a Tail-Associated Cell Wall-Degrading Activity

2004 ◽  
Vol 186 (11) ◽  
pp. 3480-3491 ◽  
Author(s):  
John G. Kenny ◽  
Stephen McGrath ◽  
Gerald F. Fitzgerald ◽  
Douwe van Sinderen
Keyword(s):  
Cell Wall ◽  
Comparative Sequence Analysis ◽  
Coding Region ◽  
Cell Binding ◽  
Binding Studies ◽  
Dna Injection ◽  
A Cell ◽  
Host Lysis ◽  
Tail Tip ◽  
Cell Binding Domain

ABSTRACT Tuc2009 is a P335-type member of the tailed-phage supergroup Siphoviridae and was originally identified as a resident prophage of the gram-positive bacterium Lactococcus lactis UC509. A Tuc2009 gene designated tal2009 which is located within the morphogenic module was shown to specify a lytic activity within the 3′ portion of its coding region. Comparative sequence analysis indicated that the cell wall-degrading part of Tal2009 is a member of the M37 protein family and that Tal2009 lacks a cell-binding domain, a finding supported by binding studies. Tal2009 appears to undergo self-mediated posttranslational processing in both L. lactis and Escherichia coli. Antibodies directed against a purified C-terminal portion of Tal2009 were used for immunoelectron microscopy, which showed that Tal2009 is located at the tail tip of Tuc2009. Antibody neutralization studies demonstrated that Tal2009-directed antibodies inhibited the ability of phage to mediate host lysis by more than 100-fold. These data indicate that tal2009 encodes a tail-associated lysin involved in localized cell wall degradation, thus allowing the Tuc2009 DNA injection machinery access to the membrane of its bacterial host.

scholarly journals Adhesive properties of osteopontin: regulation by a naturally occurring thrombin-cleavage in close proximity to the GRGDS cell-binding domain.

1994 ◽  
Vol 5 (5) ◽  
pp. 565-574 ◽  
Author(s):  
D R Senger ◽  
C A Perruzzi ◽  
A Papadopoulos-Sergiou ◽  
L Van de Water
Keyword(s):  
Cell Surface ◽  
Cleavage Site ◽  
Cell Attachment ◽  
Binding Domain ◽  
Adhesion Assay ◽  
Cell Binding ◽  
Thrombin Cleavage ◽  
Close Proximity ◽  
Alpha V Beta 3 ◽  
Cell Binding Domain

Osteopontin (OPN) is a secreted adhesive glycoprotein with a functional glycine-arginine-glycine-aspartate-serine (GRGDS) cell-binding domain. An interesting feature of OPN structure is the presence of a thrombin-cleavage site in close proximity to the GRGDS region. Cleavage of OPN by thrombin is likely to be of physiological importance, because cleavage of blood plasma OPN occurs naturally after activation of the blood coagulation pathway. To investigate functional consequences of OPN cleavage by thrombin, cell attachment and spreading assays were performed with uncleaved and cleaved forms of OPN. For all cell lines examined, thrombin-cleaved OPN promoted markedly greater cell attachment and spreading than uncleaved OPN. Cell attachment and spreading on thrombin-cleaved OPN was inhibited both by the soluble GRGDS peptides and an OPN-specific antibody raised to the GRGDS domain of OPN, thus implicating the GRGDS region in mediating the increased cell attachment and spreading observed on thrombin-cleaved OPN. Because the GRGDS sequence in OPN is only six residues from the thrombin-cleavage site, the data suggest that possibility that thrombin cleavage allows greater accessibility of the GRGDS domain to cell surface receptors. To investigate receptors that recognize uncleaved and thrombin-cleaved OPN, affinity chromatography was performed on placental extracts; the cell surface integrin alpha v beta 3 bound to columns constructed either with native or thrombin-cleaved OPN and was selectively eluted from each with soluble GRGDS peptide and EDTA. Moreover, adhesion assays performed in the presence of alpha v beta 3 blocking monoclonal antibody LM609 identified alpha v beta 3 as a major functional receptor for thrombin-cleaved OPN. Several lines of evidence suggest that cleavage of OPN by thrombin occurs in vivo, such as in tumors and at sites of tissue injury, and adhesion assay data presented here indicate that such cleavage is important in the regulation of OPN function.

scholarly journals The fibronectin-binding integrins α5β1 and αvβ3 differentially modulate RhoA–GTP loading, organization of cell matrix adhesions, and fibronectin fibrillogenesis

2002 ◽  
Vol 159 (6) ◽  
pp. 1071-1086 ◽  
Author(s):  
Erik H.J. Danen ◽  
Petra Sonneveld ◽  
Cord Brakebusch ◽  
Reinhard Fässler ◽  
Arnoud Sonnenberg
Keyword(s):  
Cell Spreading ◽  
Rapid Decrease ◽  
Cell Binding ◽  
Peripheral Cell ◽  
Rhoa Activity ◽  
Cell Matrix ◽  
Focal Contacts ◽  
Different Types ◽  
A Cell ◽  
Cell Binding Domain

We have studied the formation of different types of cell matrix adhesions in cells that bind to fibronectin via either α5β1 or αvβ3. In both cases, cell adhesion to fibronectin leads to a rapid decrease in RhoA activity. However, α5β1 but not αvβ3 supports high levels of RhoA activity at later stages of cell spreading, which are associated with a translocation of focal contacts to peripheral cell protrusions, recruitment of tensin into fibrillar adhesions, and fibronectin fibrillogenesis. Expression of an activated mutant of RhoA stimulates αvβ3-mediated fibrillogenesis. Despite the fact that α5β1-mediated adhesion to the central cell-binding domain of fibronectin supports activation of RhoA, other regions of fibronectin are required for the development of α5β1-mediated but not αvβ3-mediated focal contacts. Using chimeras of β1 and β3 subunits, we find that the extracellular domain of β1 controls RhoA activity. By expressing both β1 and β3 at high levels, we show that β1-mediated control of the levels of β3 is important for the distribution of focal contacts. Our findings demonstrate that the pattern of fibronectin receptors expressed on a cell dictates the ability of fibronectin to stimulate RhoA-mediated organization of cell matrix adhesions.

scholarly journals A Cell Binding Domain from the α3 Chain of Type IV Collagen Inhibits Proliferation of Melanoma Cells

1997 ◽  
Vol 272 (33) ◽  
pp. 20395-20401 ◽  
Author(s):  
Jing Han ◽  
Nobuko Ohno ◽  
Sylvie Pasco ◽  
Jean-Claude Monboisse ◽  
Jacques P. Borel ◽  
...  
Keyword(s):  
Type Iv Collagen ◽  
Melanoma Cells ◽  
Binding Domain ◽  
Cell Binding ◽  
Type Iv ◽  
A Cell ◽  
Cell Binding Domain

scholarly journals Clinical Efficacy and Toxicity of Anti-EGFR Therapy in Common Cancers

2009 ◽  
Vol 2009 ◽  
pp. 1-14 ◽  
Author(s):  
Amir Harandi ◽  
Aisha S. Zaidi ◽  
Abigail M. Stocker ◽  
Damian A. Laber
Keyword(s):  
Clinical Efficacy ◽  
Tyrosine Kinases ◽  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Therapeutic Agents ◽  
Efficacy Data ◽  
Cell Surface Molecule ◽  
Solid Malignancies ◽  
A Cell ◽  
Epidermal Growth

Epidermal growth factor receptor (EGFR) is a cell surface molecule and member of the ErbB family of receptor tyrosine kinases. Its activation leads to proliferation, antiapoptosis, and metastatic spread, making inhibition of this pathway a compelling target. In recent years, an increasing number of clinical trials in the management of solid malignancies have become available indicating the clinical efficacy of anti-EGFR monoclonal antibodies and oral small molecule tyrosine kinase inhibitors (TKIs). This review addresses frequently used EGFR inhibitors, summarizes clinical efficacy data of these new therapeutic agents, and discusses their associated toxicity and management.

scholarly journals The STAT5 inhibitor pimozide decreases survival of chronic myelogenous leukemia cells resistant to kinase inhibitors

Blood ◽  
2011 ◽  
Vol 117 (12) ◽  
pp. 3421-3429 ◽  
Author(s):  
Erik A. Nelson ◽  
Sarah R. Walker ◽  
Ellen Weisberg ◽  
Michal Bar-Natan ◽  
Rosemary Barrett ◽  
...  
Keyword(s):  
Chronic Myelogenous Leukemia ◽  
Tyrosine Kinases ◽  
Target Genes ◽  
Kinase Inhibitors ◽  
Bone Marrow Cells ◽  
Myelogenous Leukemia ◽  
Abl Kinase ◽  
Cycle Arrest ◽  
Expression Of Genes ◽  
A Cell

Abstract The transcription factor STAT5 is an essential mediator of the pathogenesis of chronic myelogenous leukemia (CML). In CML, the BCR/ABL fusion kinase causes the constitutive activation of STAT5, thereby driving the expression of genes promoting survival. BCR/ABL kinase inhibitors have become the mainstay of therapy for CML, although CML cells can develop resistance through mutations in BCR/ABL. To overcome this problem, we used a cell-based screen to identify drugs that inhibit STAT-dependent gene expression. Using this approach, we identified the psychotropic drug pimozide as a STAT5 inhibitor. Pimozide decreases STAT5 tyrosine phosphorylation, although it does not inhibit BCR/ABL or other tyrosine kinases. Furthermore, pimozide decreases the expression of STAT5 target genes and induces cell cycle arrest and apoptosis in CML cell lines. Pimozide also selectively inhibits colony formation of CD34+ bone marrow cells from CML patients. Importantly, pimozide induces similar effects in the presence of the T315I BCR/ABL mutation that renders the kinase resistant to presently available inhibitors. Simultaneously inhibiting STAT5 with pimozide and the kinase inhibitors imatinib or nilotinib shows enhanced effects in inhibiting STAT5 phosphorylation and in inducing apoptosis. Thus, targeting STAT5 may be an effective strategy for the treatment of CML and other myeloproliferative diseases.

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