Article

Oligomerization of CXCL10 is necessary for endothelial cell presentation and in vivo activity.

Division of Rheumatology, Allergy, and Immunology, Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA.
The Journal of Immunology (Impact Factor: 5.36). 12/2006; 177(10):6991-8. DOI: 10.4049/jimmunol.177.10.6991
Source: PubMed

ABSTRACT The chemokine IFN-gamma-inducible protein of 10 kDa (IP-10; CXCL10) plays an important role in the recruitment of activated T lymphocytes into sites of inflammation by interacting with the G protein-coupled receptor CXCR3. IP-10, like other chemokines, forms oligomers, the role of which has not yet been explored. In this study, we used a monomeric IP-10 mutant to elucidate the functional significance of oligomerization. Although monomeric IP-10 had reduced binding affinity for CXCR3 and heparin, it was able to induce in vitro chemotaxis of activated T cells with the same efficacy as wild-type IP-10. However, monomeric IP-10 was unable to induce recruitment of activated CD8+ T cells into the airways of mice after intratracheal instillation. Use of a different IP-10 mutant demonstrated that this inability was due to lack of oligomerization rather than reduced CXCR3 or heparin binding. Molecular imaging demonstrated that both wild-type and monomeric IP-10 were retained in the lung after intratracheal instillation. However, in vitro binding assays indicated that wild-type, but not monomeric, IP-10 was retained on endothelial cells and could induce transendothelial chemotaxis of activated T cells. We therefore propose that oligomerization of IP-10 is required for presentation on endothelial cells and subsequent transendothelial migration, an essential step for lymphocyte recruitment in vivo.

Download full-text

Full-text

Available from: Jan Grimm, Sep 26, 2014
0 Followers
 · 
171 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The investigation of trophoblast chemoattractive molecules in humans is of high interest for the reproductive field. Current evidence in ruminants demonstrates that CXCL10, formerly the interferon-gamma-inducible protein 10 (IP-10), is a potent chemotactic molecule implicated in the migration of trophoblast cells during early gestation. The aim of this work was to explore the existence of CXCL10/CXCR3 in the human model. Furthermore, chemotaxis assays were performed to demonstrate CXCL10 chemotactic activity in the human trophoblast cell lines JEG-3 and AC-1M88. Surprisingly, the conditioned media from epithelial endometrial cells (EEC) induced the highest trophoblast migration rate. Cytokine and chemokine membrane protein arrays were used to identify the secreted protein profile of EEC-conditioned media, and IL-6 was found to be the most abundant and CXCL13 the second most abundant molecule. Using a chemotaxis assay on AC-IM88, IL-6 antibody blocked the effect of EEC, indicating IL-6 to be an effective chemoattractive factor for trophoblast cells in the human model.
    Molecular Human Reproduction 08/2008; 14(7):423-30. DOI:10.1093/molehr/gan032 · 3.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: CXCL12alpha, a chemokine that importantly promotes the oriented cell migration and tissue homing of many cell types, regulates key homeostatic functions and pathological processes through interactions with its cognate receptor (CXCR4) and heparan sulfate (HS). The alternative splicing of the cxcl12 gene generates a recently identified isoform, CXCL12gamma, which structure/function relationships remain unexplored. The high occurrence of basic residues that characterize this isoform suggests however that it could feature specific regulation by HS. Using surface plasmon resonance and NMR spectroscopy, as well as chemically and recombinantly produced chemokines, we show here that CXCL12gamma first 68 amino acids adopt a structure closely related to the well described alpha isoform, followed by an unfolded C-terminal extension of 30 amino acids. Remarkably, 60% of these residues are either lysine or arginine, and most of them are clustered in typical HS binding sites. This provides the chemokine with the highest affinity for HP ever observed (Kd = 0.9 nM), and ensures a strong retention of the chemokine at the cell surface. This was due to the unique combination of two cooperative binding sites, one strictly required, found in the structured domain of the protein, the other one being the C-terminus which essentially functions by enhancing the half life of the complexes. Importantly, this peculiar C-terminus also regulates the balance between HS and CXCR4 binding, and consequently the biological activity of the chemokine. Together these data describe an unusual binding process that gives rise to an unprecedented high affinity between a chemokine and HS. This shows that the gamma isoform of CXCL12, which features unique structural and functional properties, is optimized to ensure its strong retention at the cell surface. Thus, depending on the chemokine isoform to which it binds, HS could differentially orchestrate the CXCL12 mediated directional cell kinesis.
    PLoS ONE 02/2007; 2(10):e1110. DOI:10.1371/journal.pone.0001110 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Osteoclasts are bone-resorbing cells derived from the myeloid lineage that play a central role in bone remodeling and inflammatory bone erosion diseases. The receptor activator of NF-kappaB ligand (RANKL) produced by osteoblasts and activated immune cells initiates the development of osteoclasts in the bone marrow. Using time series gene expression data, the intrinsic processes and the extrinsic factors that control osteoclastogenesis were identified. The gene expression profiles display distinct commitment and differentiation phases. Analysis of the time course revealed several mechanistic details, including the complex role of cholesterol in osteoclast development. Epistatic interactions and the coordination between cellular processes that regulate development were inferred from the coexpression network. The coexpression network indicated that osteoclasts induce angiogenesis and recruit T-cells to the site of osteoclastogenesis early in the commitment phase. The resulting model provides an essential framework for a better understanding of the epigenetic program of osteoclastogenesis.
    Developmental Dynamics 08/2007; 236(8):2181-97. DOI:10.1002/dvdy.21206 · 2.67 Impact Factor