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Matrix metalloproteinase processing of CXCL11/I-TAC results in loss of chemoattractant activity and altered glycosaminoglycan binding.
Cox, Jennifer H; Dean, Richard A; Roberts, Clive R; Overall, Christopher M.
Afiliação
  • Cox JH; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
J Biol Chem ; 283(28): 19389-99, 2008 Jul 11.
Article em En | MEDLINE | ID: mdl-18411283
ABSTRACT
The CXCR3 chemokine receptor regulates the migration of Th1 lymphocytes and responds to three ligands CXCL9/MIG, CXCL10/IP-10, and CXCL11/I-TAC. We screened for potential regulation of T cell responses by matrix metalloproteinase (MMP) processing of these important chemokines. The most potent of the CXCR3 ligands, CXCL11, was identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry as a substrate of the PMN-specific MMP-8, macrophage-specific MMP-12, and the general leukocyte MMP-9. The 73-amino acid residue CXCL11 is processed at both the amino and carboxyl termini to generate CXCL11-(5-73), -(5-63), and -(5-58) forms. NH2-terminal truncation results in loss of agonistic properties, as shown in calcium mobilization and chemotaxis experiments using CXCR3 transfectants and human T lymphocytes. Moreover, CXCL11-(5-73) is a CXCR3 antagonist and interestingly shows enhanced affinity to heparin. However, upon COOH-terminal truncation to position 58 there is loss of antagonist activity and heparin binding. Together this highlights an unexpected site for receptor interaction and that the carboxyl terminus is critical for glycosaminoglycan binding, an essential function for the formation of chemokine gradients in vivo. Hence, MMP activity might regulate CXCL11 tissue gradients in two ways. First, the potential of CXCL11-(5-73) to compete active CXCL11 from glycosaminoglycans might lead to the formation of an antagonistic haptotactic chemokine gradient. Second, upon further truncation, MMPs disperse the CXCL11 gradients in a novel way by proteolytic loss of a COOH-terminal GAG binding site. Hence, these results reveal potential new roles in down-regulating Th1 lymphocyte chemoattraction through MMP processing of CXCL11.
Assuntos

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Heparina / Quimiotaxia de Leucócito / Processamento de Proteína Pós-Traducional / Células Th1 / Metaloproteinases da Matriz / Quimiocina CXCL11 / Receptores CXCR3 Idioma: En Ano de publicação: 2008 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Heparina / Quimiotaxia de Leucócito / Processamento de Proteína Pós-Traducional / Células Th1 / Metaloproteinases da Matriz / Quimiocina CXCL11 / Receptores CXCR3 Idioma: En Ano de publicação: 2008 Tipo de documento: Article