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The CXC-chemokine CXCL4 interacts with integrins implicated in angiogenesis.

Aidoudi S, Bujakowska K, Kieffer N, Bikfalvi A - PLoS ONE (2008)

Bottom Line: We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner.Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration.As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

View Article: PubMed Central - PubMed

Affiliation: INSERM, U920, Talence, France. salouaaidoudi@yahoo.fr

ABSTRACT
The human CXC-chemokine CXCL4 is a potent inhibitor of tumor-induced angiogenesis. Considering that CXCL4 is sequestered in platelet alpha-granules and released following platelet activation in the vicinity of vessel wall injury, we tested the hypothesis that CXCL4 might function as a ligand for integrins. Integrins are a family of adhesion receptors that play a crucial role in angiogenesis by regulating early angiogenic processes, such as endothelial cell adhesion and migration. Here, we show that CXCL4 interacts with alphavbeta3 on the surface of alphavbeta3-CHO. More importantly, human umbilical vein endothelial cells adhere to immobilized CXCL4 through alphavbeta3 integrin, and also through other integrins, such as alphavbeta5 and alpha5beta1. We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner. Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration. As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

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CXCL4 or CXCL4/CTF binds to purified αvβ3 integrins in a concentration-dependent and specific manners in solid-phase ligand binding assay.Α. αvβ3 integrin was added to wells coated with CXCL4 or CXCL4/CTF as indicated, and incubated overnight at 4°C. Anti-αv, peroxidase-conjugated anti-rabbit IgG antibodies, and TMB substrate were used to detect bound integrin. B. Soluble RGD-, RGE peptides or inhibitory anti-integrin antibodies were added to block the interaction between CXCL4 or CXCL4/CTF and αvβ3 integrin. Bound integrin was detected as above. Anti-integrin antibodies used were: anti-αv (AV1) and anti-β3 (B3A). Error bars represent the mean±SD, *, P≤0.005; **, P≤0,0005 compared to CXCL4 or CXCL4/CTF in the presence of IgM control antibody; n = 3 independent experiments.
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pone-0002657-g003: CXCL4 or CXCL4/CTF binds to purified αvβ3 integrins in a concentration-dependent and specific manners in solid-phase ligand binding assay.Α. αvβ3 integrin was added to wells coated with CXCL4 or CXCL4/CTF as indicated, and incubated overnight at 4°C. Anti-αv, peroxidase-conjugated anti-rabbit IgG antibodies, and TMB substrate were used to detect bound integrin. B. Soluble RGD-, RGE peptides or inhibitory anti-integrin antibodies were added to block the interaction between CXCL4 or CXCL4/CTF and αvβ3 integrin. Bound integrin was detected as above. Anti-integrin antibodies used were: anti-αv (AV1) and anti-β3 (B3A). Error bars represent the mean±SD, *, P≤0.005; **, P≤0,0005 compared to CXCL4 or CXCL4/CTF in the presence of IgM control antibody; n = 3 independent experiments.

Mentions: To reinforce the results described above, we studied the direct interaction of CXCL4, or CXCL4/CTF, to integrin in a solid-phase ligand binding assay [27] using a purified human integrin αvβ3 (protein). As shown in Fig. 3A, soluble αvβ3 demonstrates a concentration- dependent and saturable binding to immobilized CXCL4 or its peptide CXCL4/CTF. The specificity of the interaction was confirmed by inhibition of CXCL4 or CXCL4/CTF binding to αvβ3 integrin with the inhibitory αv (AV1) and β3 (B3A) antibodies, as well with RGD peptides (Fig. 3B). Thus, these results demonstrate a specific and direct interaction between the angiogenic inhibitor CXCL4 or its peptide CXCL4/CTF with the αvβ3 integrin.


The CXC-chemokine CXCL4 interacts with integrins implicated in angiogenesis.

Aidoudi S, Bujakowska K, Kieffer N, Bikfalvi A - PLoS ONE (2008)

CXCL4 or CXCL4/CTF binds to purified αvβ3 integrins in a concentration-dependent and specific manners in solid-phase ligand binding assay.Α. αvβ3 integrin was added to wells coated with CXCL4 or CXCL4/CTF as indicated, and incubated overnight at 4°C. Anti-αv, peroxidase-conjugated anti-rabbit IgG antibodies, and TMB substrate were used to detect bound integrin. B. Soluble RGD-, RGE peptides or inhibitory anti-integrin antibodies were added to block the interaction between CXCL4 or CXCL4/CTF and αvβ3 integrin. Bound integrin was detected as above. Anti-integrin antibodies used were: anti-αv (AV1) and anti-β3 (B3A). Error bars represent the mean±SD, *, P≤0.005; **, P≤0,0005 compared to CXCL4 or CXCL4/CTF in the presence of IgM control antibody; n = 3 independent experiments.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2481302&req=5

pone-0002657-g003: CXCL4 or CXCL4/CTF binds to purified αvβ3 integrins in a concentration-dependent and specific manners in solid-phase ligand binding assay.Α. αvβ3 integrin was added to wells coated with CXCL4 or CXCL4/CTF as indicated, and incubated overnight at 4°C. Anti-αv, peroxidase-conjugated anti-rabbit IgG antibodies, and TMB substrate were used to detect bound integrin. B. Soluble RGD-, RGE peptides or inhibitory anti-integrin antibodies were added to block the interaction between CXCL4 or CXCL4/CTF and αvβ3 integrin. Bound integrin was detected as above. Anti-integrin antibodies used were: anti-αv (AV1) and anti-β3 (B3A). Error bars represent the mean±SD, *, P≤0.005; **, P≤0,0005 compared to CXCL4 or CXCL4/CTF in the presence of IgM control antibody; n = 3 independent experiments.
Mentions: To reinforce the results described above, we studied the direct interaction of CXCL4, or CXCL4/CTF, to integrin in a solid-phase ligand binding assay [27] using a purified human integrin αvβ3 (protein). As shown in Fig. 3A, soluble αvβ3 demonstrates a concentration- dependent and saturable binding to immobilized CXCL4 or its peptide CXCL4/CTF. The specificity of the interaction was confirmed by inhibition of CXCL4 or CXCL4/CTF binding to αvβ3 integrin with the inhibitory αv (AV1) and β3 (B3A) antibodies, as well with RGD peptides (Fig. 3B). Thus, these results demonstrate a specific and direct interaction between the angiogenic inhibitor CXCL4 or its peptide CXCL4/CTF with the αvβ3 integrin.

Bottom Line: We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner.Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration.As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

View Article: PubMed Central - PubMed

Affiliation: INSERM, U920, Talence, France. salouaaidoudi@yahoo.fr

ABSTRACT
The human CXC-chemokine CXCL4 is a potent inhibitor of tumor-induced angiogenesis. Considering that CXCL4 is sequestered in platelet alpha-granules and released following platelet activation in the vicinity of vessel wall injury, we tested the hypothesis that CXCL4 might function as a ligand for integrins. Integrins are a family of adhesion receptors that play a crucial role in angiogenesis by regulating early angiogenic processes, such as endothelial cell adhesion and migration. Here, we show that CXCL4 interacts with alphavbeta3 on the surface of alphavbeta3-CHO. More importantly, human umbilical vein endothelial cells adhere to immobilized CXCL4 through alphavbeta3 integrin, and also through other integrins, such as alphavbeta5 and alpha5beta1. We further demonstrate that CXCL4-integrin interaction is of functional significance in vitro, since immobilized CXCL4 supported endothelial cell spreading and migration in an integrin-dependent manner. Soluble CXCL4, in turn, inhibits integrin-dependent endothelial cell adhesion and migration. As a whole, our study identifies integrins as novel receptors for CXCL4 that may contribute to its antiangiogenic effect.

Show MeSH
Related in: MedlinePlus