Integrins αvβ3 and α 4β1 act as coreceptors for fractalkine, and the integrin-binding defective mutant of fractalkine is an antagonist of CX3CR1

Masaaki Fujita, Yoko K. Takada, Yoshikazu Takada

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The membrane-bound chemokine fractalkine (FKN, CX3CL1) on endothelial cells plays a role in leukocyte trafficking. The chemokine domain (FKN-CD) is sufficient for inducing FKN signaling (e.g., integrin activation), and FKN-CD binds to its receptor CX3CR1 on leukocytes. Whereas previous studies suggest that FKN-CD does not directly bind to integrins, our docking simulation studies predicted that FKN-CD directly interacts with integrin αvβ 3. Consistent with this prediction, we demonstrated that FKNCD directly bound to αvβ3 and α 4β1 at a very high affinity (KD of 3.0 × 10-10 M to αvβ3 in 1 mM Mn2+). Also, membrane-bound FKN bound to integrins αvβ3 and α4β1, suggesting that the FKN-CD/integrin interaction is biologically relevant. The binding site for FKN-CD in αvβ3 was similar to those for other known αvβ3 ligands. Wild-type FKN-CD induced coprecipitation of integrins and CX3CR1 in U937 cells, suggesting that FKN-CD induces ternary complex formation (CX3CR1, FKN-CD, and integrin). Based on the docking model, we generated an integrin-binding defective FKN-CD mutant (the K36E/R37E mutant). K36E/R37E was defective in ternary complex formation and integrin activation, whereas K36E/R37E still bound to CX3CR1. These results suggest that FKN-CD binding to CX3CR1 is not sufficient for FKN signaling, and that FKN-CD binding to integrins as coreceptors and the resulting ternary complex formation are required for FKN signaling. Notably, excess K36E/R37E suppressed integrin activation induced by wild-type FKN-CD and effectively suppressed leukocyte infiltration in thioglycollate-induced peritonitis. These findings suggest that K36E/R37E acts as a dominant-negative CX3CR1 antagonist and that FKN-CD/ integrin interaction is a novel therapeutic target in inflammatory diseases.

Original languageEnglish
Pages (from-to)5809-5819
Number of pages11
JournalJournal of Immunology
Volume189
Issue number12
DOIs
Publication statusPublished - Dec 15 2012
Externally publishedYes

Fingerprint

Chemokine CX3CL1
Integrins
Leukocytes
Chemokines
Thioglycolates
U937 Cells
Membranes
Peritonitis

ASJC Scopus subject areas

  • Immunology

Cite this

Integrins αvβ3 and α 4β1 act as coreceptors for fractalkine, and the integrin-binding defective mutant of fractalkine is an antagonist of CX3CR1. / Fujita, Masaaki; Takada, Yoko K.; Takada, Yoshikazu.

In: Journal of Immunology, Vol. 189, No. 12, 15.12.2012, p. 5809-5819.

Research output: Contribution to journalArticle

@article{a887580a89bc4e8d990cb75af755f62d,
title = "Integrins αvβ3 and α 4β1 act as coreceptors for fractalkine, and the integrin-binding defective mutant of fractalkine is an antagonist of CX3CR1",
abstract = "The membrane-bound chemokine fractalkine (FKN, CX3CL1) on endothelial cells plays a role in leukocyte trafficking. The chemokine domain (FKN-CD) is sufficient for inducing FKN signaling (e.g., integrin activation), and FKN-CD binds to its receptor CX3CR1 on leukocytes. Whereas previous studies suggest that FKN-CD does not directly bind to integrins, our docking simulation studies predicted that FKN-CD directly interacts with integrin αvβ 3. Consistent with this prediction, we demonstrated that FKNCD directly bound to αvβ3 and α 4β1 at a very high affinity (KD of 3.0 × 10-10 M to αvβ3 in 1 mM Mn2+). Also, membrane-bound FKN bound to integrins αvβ3 and α4β1, suggesting that the FKN-CD/integrin interaction is biologically relevant. The binding site for FKN-CD in αvβ3 was similar to those for other known αvβ3 ligands. Wild-type FKN-CD induced coprecipitation of integrins and CX3CR1 in U937 cells, suggesting that FKN-CD induces ternary complex formation (CX3CR1, FKN-CD, and integrin). Based on the docking model, we generated an integrin-binding defective FKN-CD mutant (the K36E/R37E mutant). K36E/R37E was defective in ternary complex formation and integrin activation, whereas K36E/R37E still bound to CX3CR1. These results suggest that FKN-CD binding to CX3CR1 is not sufficient for FKN signaling, and that FKN-CD binding to integrins as coreceptors and the resulting ternary complex formation are required for FKN signaling. Notably, excess K36E/R37E suppressed integrin activation induced by wild-type FKN-CD and effectively suppressed leukocyte infiltration in thioglycollate-induced peritonitis. These findings suggest that K36E/R37E acts as a dominant-negative CX3CR1 antagonist and that FKN-CD/ integrin interaction is a novel therapeutic target in inflammatory diseases.",
author = "Masaaki Fujita and Takada, {Yoko K.} and Yoshikazu Takada",
year = "2012",
month = "12",
day = "15",
doi = "10.4049/jimmunol.1200889",
language = "English",
volume = "189",
pages = "5809--5819",
journal = "Journal of Immunology",
issn = "0022-1767",
publisher = "American Association of Immunologists",
number = "12",

}

TY - JOUR

T1 - Integrins αvβ3 and α 4β1 act as coreceptors for fractalkine, and the integrin-binding defective mutant of fractalkine is an antagonist of CX3CR1

AU - Fujita, Masaaki

AU - Takada, Yoko K.

AU - Takada, Yoshikazu

PY - 2012/12/15

Y1 - 2012/12/15

N2 - The membrane-bound chemokine fractalkine (FKN, CX3CL1) on endothelial cells plays a role in leukocyte trafficking. The chemokine domain (FKN-CD) is sufficient for inducing FKN signaling (e.g., integrin activation), and FKN-CD binds to its receptor CX3CR1 on leukocytes. Whereas previous studies suggest that FKN-CD does not directly bind to integrins, our docking simulation studies predicted that FKN-CD directly interacts with integrin αvβ 3. Consistent with this prediction, we demonstrated that FKNCD directly bound to αvβ3 and α 4β1 at a very high affinity (KD of 3.0 × 10-10 M to αvβ3 in 1 mM Mn2+). Also, membrane-bound FKN bound to integrins αvβ3 and α4β1, suggesting that the FKN-CD/integrin interaction is biologically relevant. The binding site for FKN-CD in αvβ3 was similar to those for other known αvβ3 ligands. Wild-type FKN-CD induced coprecipitation of integrins and CX3CR1 in U937 cells, suggesting that FKN-CD induces ternary complex formation (CX3CR1, FKN-CD, and integrin). Based on the docking model, we generated an integrin-binding defective FKN-CD mutant (the K36E/R37E mutant). K36E/R37E was defective in ternary complex formation and integrin activation, whereas K36E/R37E still bound to CX3CR1. These results suggest that FKN-CD binding to CX3CR1 is not sufficient for FKN signaling, and that FKN-CD binding to integrins as coreceptors and the resulting ternary complex formation are required for FKN signaling. Notably, excess K36E/R37E suppressed integrin activation induced by wild-type FKN-CD and effectively suppressed leukocyte infiltration in thioglycollate-induced peritonitis. These findings suggest that K36E/R37E acts as a dominant-negative CX3CR1 antagonist and that FKN-CD/ integrin interaction is a novel therapeutic target in inflammatory diseases.

AB - The membrane-bound chemokine fractalkine (FKN, CX3CL1) on endothelial cells plays a role in leukocyte trafficking. The chemokine domain (FKN-CD) is sufficient for inducing FKN signaling (e.g., integrin activation), and FKN-CD binds to its receptor CX3CR1 on leukocytes. Whereas previous studies suggest that FKN-CD does not directly bind to integrins, our docking simulation studies predicted that FKN-CD directly interacts with integrin αvβ 3. Consistent with this prediction, we demonstrated that FKNCD directly bound to αvβ3 and α 4β1 at a very high affinity (KD of 3.0 × 10-10 M to αvβ3 in 1 mM Mn2+). Also, membrane-bound FKN bound to integrins αvβ3 and α4β1, suggesting that the FKN-CD/integrin interaction is biologically relevant. The binding site for FKN-CD in αvβ3 was similar to those for other known αvβ3 ligands. Wild-type FKN-CD induced coprecipitation of integrins and CX3CR1 in U937 cells, suggesting that FKN-CD induces ternary complex formation (CX3CR1, FKN-CD, and integrin). Based on the docking model, we generated an integrin-binding defective FKN-CD mutant (the K36E/R37E mutant). K36E/R37E was defective in ternary complex formation and integrin activation, whereas K36E/R37E still bound to CX3CR1. These results suggest that FKN-CD binding to CX3CR1 is not sufficient for FKN signaling, and that FKN-CD binding to integrins as coreceptors and the resulting ternary complex formation are required for FKN signaling. Notably, excess K36E/R37E suppressed integrin activation induced by wild-type FKN-CD and effectively suppressed leukocyte infiltration in thioglycollate-induced peritonitis. These findings suggest that K36E/R37E acts as a dominant-negative CX3CR1 antagonist and that FKN-CD/ integrin interaction is a novel therapeutic target in inflammatory diseases.

UR - http://www.scopus.com/inward/record.url?scp=84871119591&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84871119591&partnerID=8YFLogxK

U2 - 10.4049/jimmunol.1200889

DO - 10.4049/jimmunol.1200889

M3 - Article

VL - 189

SP - 5809

EP - 5819

JO - Journal of Immunology

JF - Journal of Immunology

SN - 0022-1767

IS - 12

ER -