Natural nitration of CXCL12 reduces its signaling capacity and chemotactic activity in vitro and abrogates intra-articular lymphocyte recruitment in vivo

Rik Janssens, Anneleen Mortier, Daiane Boff, Vincent Vanheule, Mieke Gouwy, Charlotte Franck, Olav Larsen, Mette M. Rosenkilde, Jo Van Damme, Flávio A. Amaral, Mauro M. Teixeira, Sofie Struyf, Paul Proost*

*Corresponding author for this work

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    Abstract

    The chemokine CXCL12/stromal cell-derived factor-1 is important for leukocyte migration to lymphoid organs and inflamed tissues and stimulates tumor development. In vitro, CXCL12 activity through CXCR4 is abolished by proteolytic processing. However, limited information is available on in vivo effects of posttranslationally modified CXCL12. Natural CXCL12 was purified from the coculture supernatant of stromal cells stimulated with leukocytes and inflammatory agents. In this conditioned medium, CXCL12 with a nitration on Tyr7, designated [3-NT7]CXCL12, was discovered via Edman degradation. CXCL12 and [3-NT7]CXCL12 were chemically synthesized to evaluate the biological effects of this modification. [3-NT7]CXCL12 recruited β-arrestin 2 and phosphorylated the Akt kinase similar to CXCL12 in receptor-transfected cells. Also the affinity of CXCL12 and [3-NT7]CXCL12 for glycosaminoglycans, the G protein-coupled chemokine receptor CXCR4 and the atypical chemokine receptor ACKR3 were comparable. However, [3-NT7]CXCL12 showed a reduced ability to enhance intracellular calcium concentrations, to generate inositol triphosphate, to phosphorylate ERK1/2 and to induce monocyte and lymphocyte chemotaxis in vitro. Moreover, nitrated CXCL12 failed to induce in vivo extravasation of lymphocytes to the joint. In summary, nitration on Tyr7 under inflammatory conditions is a novel natural posttranslational regulatory mechanism of CXCL12 which may downregulate the CXCR4-mediated inflammatory and tumor-promoting activities of CXCL12.

    Original languageEnglish
    JournalOncoTarget
    Volume7
    Issue number38
    Pages (from-to)62439-62459
    Number of pages21
    ISSN1949-2553
    DOIs
    Publication statusPublished - 2016

    Keywords

    • Chemokine
    • Chemotaxis
    • Extravasation
    • Lymphocyte migration
    • Posttranslational modification

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