Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The presence of the extracellular matrix protein thrombospondin (TSP) at sites of tissue injury or inflammation may promote monocyte migration to these sites and play a central role in their eventual differentiation into tissue macrophages. Previously, we have shown that TSP promotes neutrophil adhesion and migration, and primes for oxidant generation. To examine the effect of TSP on monocyte motility, we conducted chemotaxis assays in modified Boyden chambers. TSP was chemotactic for monocytes, with a maximal response at 200 to 500 nM TSP. Checkerboard analysis confirmed that migration was directional. mAb C6.7, against the distal COOH terminus of TSP, inhibited chemotaxis, demonstrating specificity and indicating that the chemotactic activity resides in the COOH terminus. Consistent with the mAb data, the COOH-terminal 140-kDa proteolytic fragment of TSP was chemotactic for monocytes, whereas the NH2-terminal heparin-binding domain was inactive. A synthetic peptide containing the sequence CSVT, derived from the type I repeats of TSP, was also chemotactic. Thus, two different sites on the COOH terminus of TSP are capable of stimulating monocyte chemotaxis. Pertussis toxin, but not cholera toxin, completely inhibited TSP-mediated chemotaxis, suggesting the involvement of GTP-binding proteins. TSP bound to polycarbonate filters stimulated monocyte haptotaxis, with a maximal response at 4 pmol. The directional nature of this motility was confirmed by checkerboard analysis. Monocyte haptotaxis was inhibited by two different mAbs recognizing distinct sites on the COOH terminus. As with chemotaxis, the 140-kDa fragment, but not the heparin-binding domain, contained the haptotactic activity. The CSVT-containing synthetic peptide also promoted monocyte haptotaxis. But, in contrast to chemotaxis, neither pertussis toxin nor cholera toxin inhibited TSP-mediated haptotaxis, suggesting the involvement of a different signal transduction pathway. mAbs against GPIV, beta 1, beta 3, or alpha v integrins did not affect monocyte chemotaxis or haptotaxis, ruling out the involvement of these receptors. These results indicate that TSP is likely to play an important role in monocyte recruitment to an inflammatory or injury site.
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PMID:Thrombospondin promotes chemotaxis and haptotaxis of human peripheral blood monocytes. 793 Jun 24

Differentiation of the human promyelocytic leukemia cell line HL-60 to polymorphonuclear leukocyte (PMN)-like cells with DMSO provides an important model for studying the acquisition of PMN functional responses that accompany differentiation. We showed previously that the extracellular matrix (ECM) protein thrombospondin (TSP) binds to PMN surface receptors and promotes adhesion and motility. Undifferentiated HL-60 cells did not adhere and were not motile in response to TSP, whereas cells differentiated toward PMN-like cells demonstrated both TSP-mediated adhesion and chemotaxis, with chemotaxis evident by day 2 of induction. With differentiation, a maximal response was obtained with 100 to 300 nM TSP, 10-fold lower than required for maximal PMN chemotaxis. Checkerboard analysis confirmed the directional nature of motility. mAb recognizing different domains of TSP inhibited chemotaxis, suggesting the involvement of multiple sites on TSP. Although both the NH2-terminal heparin-binding domain (HBD) and 140 kDa COOH-terminal fragment supported chemotaxis in PMN-like cells, neither fragment was as potent as intact TSP. Both pertussis and cholera toxin inhibited TSP-mediated chemotaxis, suggesting the involvement of GTP-binding proteins. The toxin effects did not indirectly result from elevated cAMP levels because high concentrations of either 8-bromo-cAMP or dibutyryl cAMP did not inhibit chemotaxis. TSP bound to nitrocellulose filters induced the directed migration (haptotaxis) of PMN-like cells rather than the random motility observed with PMN. Haptotaxis was stimulated by either the HBD or 140-kDa fragment and was inhibited by mAb against these two domains. Haptotaxis rather than random migration was confirmed by checkerboard analysis. Our results demonstrate that PMN-like HL-60 cells respond differently to TSP than human peripheral blood PMN. These differences may reflect 1) an aberration in HL-60 differentiation reflecting their leukemic phenotype 2) differentiation of HL-60 cells to a cell type characteristic of "activated" PMN.
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PMID:Thrombospondin promotes both chemotaxis and haptotaxis in neutrophil-like HL-60 cells. 843 28

The extracellular matrix (ECM) protein thrombospondin (TSP) binds to specific receptors on polymorphonuclear leukocytes (PMNs) and stimulates motility. TSP can also enhance the response of PMNs to the formylated peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP). Our initial evidence suggesting that PMN TSP receptors were linked to GTP-binding proteins (G-proteins) came from studies using pertussis toxin (PT) and cholera toxin (CT) to inhibit TSP-mediated motility. Both PT and CT inhibited TSP-mediated chemotaxis and substrate-associated random migration. Inhibition was not indirectly caused by a rise in cAMP since neither dibutyryl cAMP (300 microM) nor 8-bromo-cAMP (300 microM) significantly affected TSP-mediated motility. In fact, TSP itself caused a significant rise in intracellular cAMP levels (from 7.2 +/- 0.3 to 14.2 +/- 0.1 pmol/10(6) cells). Although we could not test the PT sensitivity of TSP priming for FMLP-mediated chemotaxis (as PT inhibits FMLP-mediated chemotaxis itself), we evaluated the effect of CT on this response. CT completely abolished TSP-dependent priming of FMLP-mediated chemotaxis. Direct evidence for an interaction between TSP receptors and G-proteins was obtained by examining the effect of TSP on alpha-subunit ADP-ribosylation, GTPase activity, and GTP gamma S binding. We observed a decrease in the ability of FMLP to stimulate GTPase activity on membranes isolated from PMNs incubated with TSP. Furthermore, the PT-dependent ribosylation of Ci alpha 2,3 stimulated by FMLP was eliminated by TSP treatment. These data indicated that the two receptors share a pool of G-proteins. However, TSP did not block the CT-dependent ribosylation stimulated by FMLP, suggesting that TSP receptors may also interact with a different pool of Gi alpha 2,3. TSP itself significantly (P < 0.005) increased GTP hydrolysis in PMN membranes (to 110.6 +/- 2.7% of control values). In addition, GTP gamma S binding to membranes increased significantly (P < 0.005) following exposure to 10 nM TSP (to 108 +/- 1.4% of control values). Conversely, GTP treatment reduced the affinity of TSP for its receptor without altering total binding. These data demonstrate that TSP receptors are linked to G-proteins, a subpopulation of which also associates with FMLP receptors.
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PMID:Neutrophil thrombospondin receptors are linked to GTP-binding proteins. 864 18

Integrin-associated protein (IAP or CD47) is a receptor for the cell/platelet-binding domain (CBD) of thrombospondin-1 (TS1), the most abundant protein of platelet alpha granules. Although it associates with alphaIIbbeta3, IAP has no known function in platelets. TS1, the CBD, and an IAP agonist peptide (4N1K) from the CBD of TS1 activate the platelet integrin alphaIIbbeta3, resulting in platelet spreading on immobilized fibrinogen, stimulation of platelet aggregation, and enhanced tyrosine phosphorylation of focal adhesion kinase. Furthermore, 4N1K peptide selectively stimulates the phosphorylation of LYN and SYK and their association with FAK. The phosphorylation of SYK is blocked by pertussis toxin, implicating a Gi-like heterotrimeric G protein. IAP solublized from membranes of unstimulated platelets binds specifically to an affinity column of 4N1K peptide. Both alphaIIb and beta3 integrin subunits and c-Src bind along with IAP. This complex of proteins is also detected with immunoprecipitation. Activation of platelets with the agonist peptide 4N1K results in the association of FAK with the IAP-alphaIIbbeta3 complex. Thus an important function of TS1 in platelets is that of a secreted costimulator of alphaIIbbeta3 whose unique properties result in its localization to the platelet surface and the fibrin clot.
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PMID:Thrombspondin acts via integrin-associated protein to activate the platelet integrin alphaIIbbeta3. 916 39

Integrin-associated protein (IAP; CD47) is a thrombospondin receptor that forms a signaling complex with beta3 integrins resulting in enhanced alphavbeta3-dependent cell spreading and chemotaxis and, in platelets, alphaIIbbeta3-dependent spreading and aggregation. These actions of CD47 are all specifically abrogated by pertussis toxin treatment of cells. Here we report that CD47, its beta3 integrin partner, and Gi proteins form a stable, detergent-soluble complex that can be recovered by immunoprecipitation and affinity chromatography. Gialpha is released from this complex by treatment with GTP or AlF4. GTP and AlF4 also reduce the binding of CD47 to its agonist peptide (4N1K) derived from thrombospondin, indicating a direct association of CD47 with Gi. 4N1K peptide causes a rapid decrease in intraplatelet cyclic AMP levels, a Gi-dependent event necessary for aggregation. Finally, 4N1K stimulates the binding of GTPgamma35S to membranes from cells expressing IAP and alphavbeta3. This functional coupling of CD47 to heterotrimeric G proteins provides a mechanistic explanation for the biological effects of CD47 in a wide variety of systems.
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PMID:The thrombospondin receptor integrin-associated protein (CD47) functionally couples to heterotrimeric Gi. 1008 89

CD47-binding sequences from the carboxyl-terminal domain of thrombospondin-1 (TSP1) are known to regulate activity of the alpha(v)beta(3) integrin (Gao, G., Lindberg, F. P., Dimitry, J. M., Brown, E. J., and Frazier, W. A. (1996) J. Cell Biol. 135, 533-544). Here we show that peptides from the type 1 repeats of TSP1 also stimulate alpha(v)beta(3) integrin function in melanoma cells. Addition of soluble peptide 246 (KRFKQDGGWSHWSPWSS) enhances spreading of A2058 melanoma cells on several alpha(v)beta(3) integrin ligands, including vitronectin, recombinant TSP1 fragments containing the Arg-Gly-Asp sequence, and native TSP1. This activity requires the Trp residues and is independent of CD36-binding sequences in the type 1 repeats. Recombinant type 1 repeats expressed as a glutathione S-transferase fusion protein also enhance spreading on vitronectin and TSP1. Activation of alpha(v)beta(3) integrin by the soluble peptide 246 stimulates organization of F-actin and increases tyrosine phosphorylation of focal adhesion kinase. In contrast, direct adhesion of melanoma cells on immobilized peptide 246 inhibits tyrosine phosphorylation of focal adhesion kinase. Stimulation of alpha(v)beta(3) integrin function by the type 1 repeat peptide differs from that induced by CD47-binding TSP1 peptides in that heparan sulfate proteoglycans are required and pertussis toxin does not inhibit the former activity. Thus, the type 1 repeats contain a second sequence of TSP1 that can enhance alpha(v)beta(3) integrin signaling, and these two sequences stimulate recognition of both vitronectin and TSP1 by the alpha(v)beta(3) integrin.
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PMID:Cooperation between thrombospondin-1 type 1 repeat peptides and alpha(v)beta(3) integrin ligands to promote melanoma cell spreading and focal adhesion kinase phosphorylation. 1042 59

Integrin-associated protein (IAP/CD47) augments the function of alpha2beta1 integrin in smooth muscle cells (SMC), resulting in enhanced chemotaxis toward soluble collagen (Wang, X-Q., and W.A. Frazier. 1998. Mol. Biol. Cell. 9:865). IAP-deficient SMC derived from IAP(-/-) animals did not migrate in response to 4N1K (KRFYVVMWKK), a peptide agonist of IAP derived from the COOH-terminal domain of thrombospondin-1 (TSP1). When normal SMC were preincubated with 4N1K or an anti-alpha2beta1 function-stimulating antibody, cell migration to soluble collagen was significantly enhanced. 4N1K-induced chemotaxis was blocked by treatment of SMC with pertussis toxin indicating that IAP acts through Gi. In agreement with this, 4N1K evoked a rapid decrease in cAMP levels which was intensified in the presence of collagen, and forskolin and 8-Br-cAMP both inhibited SMC migration stimulated via IAP. 4N1K strongly inhibited extracellular regulated kinase (ERK) activation in SMC attaching to collagen and reduced basal ERK activity in suspended SMC. Pertussis toxin treatment of SMC significantly activated ERK, suggesting that an inhibitory input was alleviated. Inhibition of ERK activity by (a) the MAP kinase kinase (MEK) inhibitor, PD98059, (b) antisense oligonucleotide depletion of ERK, and (c) expression of mitogen-activated protein (MAP) kinase phosphatase-1 in SMC all led to increased migration to collagen, 4N1K, or 4N1K plus collagen. Thus, IAP stimulates alpha2beta1 integrin-mediated SMC migration via Gi-mediated inhibition of ERK activity and suppression of cyclic AMP levels. Both of these signaling pathways could directly modulate the state of the integrin as well as impact downstream components of the cell motility apparatus.
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PMID:Integrin-associated protein stimulates alpha2beta1-dependent chemotaxis via Gi-mediated inhibition of adenylate cyclase and extracellular-regulated kinases. 1052 43

The cellular phospholipid, lysophosphatidic acid (LPA), released by activated platelets and fibroblasts or, at high levels, from ovarian and cervical carcinomas is a powerful serum mitogen that may modulate several signaling pathways in endothelial cells (EC). Hence, LPA could function in a paracrine manner during EC-platelet interactions at sites of vascular injury. Here, we demonstrate activation of the transcription factor nuclear factor kappa B (NF-kappaB) in EC following exposure to LPA. EC activation was further characterized by increased levels of mRNA transcripts encoding E-selectin, Intercellular Adhesion Molecule-1, Interleukin-8 and Monocyte Chemoattractant Protein-1. These effects were inhibited by preincubating EC either in the presence of mepacrine (to block phospholipase A2) or of pertussis toxin (to increase ADP-ribosylation of Gi proteins). No inhibition was observed in the presence of putative LPA receptor antagonists suramin or thrombospondin. LPA induces a proinflammatory activation of endothelial cells that (i) involves Gi proteins; (ii) depends on phospholipase A2 activity; (iii) is associated with the activation of NF-kappaB and (iv) results in increased expression of proinflammatory genes. We propose that LPA release by activated platelets may directly modulate vascular inflammatory responses.
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PMID:Lysophosphatidic acid activates nuclear factor kappa B and induces proinflammatory gene expression in endothelial cells. 1059 50

The matricellular protein thrombospondin (TSP) stimulates stress fiber and focal adhesion disassembly through a sequence (hep I) in its heparin-binding domain. TSP/hep I signals focal adhesion disassembly by binding cell surface calreticulin (CRT) and activating phosphoinositide 3-kinase (PI3K). However, other components of this signaling pathway have not been identified. We now show that TSP induces focal adhesion disassembly through activation of pertussis toxin (PTX)-sensitive G proteins and ERK phosphorylation. PTX pretreatment inhibits TSP/hep I-mediated focal adhesion disassembly as well as PI3K activation. In addition, membrane-permeable Galpha(i2)- and Gbetagamma-blocking peptides inhibit hep I-mediated focal adhesion disassembly. Hep I stimulates a transient increase in ERK activation, which is abrogated by both PTX and PI3K inhibitors. Inhibiting ERK activation with MEK inhibitors blocks hep I-mediated focal adhesion disassembly, indicating that ERK activation is required for cytoskeletal reorganization. G protein signals and ERK phosphorylation are induced by TSP binding to cell surface CRT, because CRT null mouse embryonic fibroblasts (MEF) fail to stimulate ERK phosphorylation in response to TSP/hep I treatment. These data show that G(i) protein and ERK, in concert with PI3K, are stimulated by TSP.CRT interactions at the cell surface to induce de-adhesive changes in the cytoskeleton.
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PMID:Thrombospondin stimulates focal adhesion disassembly through Gi- and phosphoinositide 3-kinase-dependent ERK activation. 1192 91

We examined the regulation of alpha4beta1 integrin function in melanoma cells and T cells by ligands of CD47. A CD47 antibody (B6H12) that inhibited alphavbeta3-mediated adhesion of melanoma cells induced by CD47-binding peptides from thrombospondin-1 directly stimulated alpha4beta1-mediated adhesion of the same cells to vascular cell adhesion molecule-1 and N-terminal regions of thrombospondin-1 or thrombospondin-2. B6H12 also stimulated alpha4beta1- as well as alpha2beta1- and alpha5beta1-mediated adhesion of CD47-expressing T cells but not of CD47-deficient T cells. alpha4beta1 and CD47 co-purified as a detergent-stable complex on a CD47 antibody affinity column. CD47-binding peptides based on C-terminal sequences of thrombospondin-1 also specifically enhanced adhesion of melanoma cells and T cells to alpha4beta1 ligands. Unexpectedly, activation of alpha4beta1 function by the thrombospondin-1 CD47-binding peptides also occurred in CD47-deficient T cells. CD47-independent activation of alpha4beta1 required the Val-Val-Met (VVM) motif of the peptides and was sensitive to inhibition by pertussis toxin. These results indicate that activation of alpha4beta1 by the CD47 antibody B6H12 and by VVM peptides occurs by different mechanisms. The antibody directly activates a CD47-alpha4beta1 complex, whereas VVM peptides may target an unidentified Gi-linked receptor that regulates alpha4beta1.
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PMID:Regulation of integrin function by CD47 ligands. Differential effects on alpha vbeta 3 and alpha 4beta1 integrin-mediated adhesion. 1221 55


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