IL-1 enhances cell adhesion to degraded fibronectin

*Matrix Dynamics Group, University of Toronto, Toronto, Ontario, Canada
The FASEB Journal (Impact Factor: 5.04). 07/2012; 26(11). DOI: 10.1096/fj.12-207381
Source: PubMed


IL-1β is a prominent proinflammatory cytokine that mediates degradation of extracellular matrix proteins through increased expression of matrix metalloproteinases, which involves a signaling pathway in adherent cells that is restricted by focal adhesions. Currently, the mechanism by which IL-1β affects cell adhesion to matrix proteins is not defined, and it is not known whether degraded matrix proteins affect IL-1β signaling. We examined adhesion-related IL-1β signaling in fibroblasts attaching to native or MMP3-degraded fibronectin. IL-1β increased cell attachment, resistance to shear force and the numbers of focal adhesions containing activated β(1) integrins. IL-1β-enhanced attachment required FAK, kindlins 1/2, and talin. MMP3-degraded fibronectin-inhibited IL-1β-enhanced cell adhesion and promoted spontaneous ERK activation that was independent of IL-1β treatment. We conclude that IL-1β enhances the adhesion of anchorage-dependent cells to MMP3-degraded fibronectin, which, in turn, is associated with deregulated cellular responses to IL-1β. These data point to a novel role of IL-1β as a proadhesive signaling molecule in inflammation that employs kindlins and talin to regulate adhesion.-Rajshankar, D., Downey, G. P., McCulloch, C. A. IL-1β enhances cell adhesion to degraded fibronectin.

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Available from: Gregory P Downey, Oct 12, 2015
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    • "DDR1 over-expression enhances activated b1 integrins in focal adhesions Although DDR1 does not localize to focal adhesions (Vogel et al., 2000), we determined whether over-expression of DDR1 might influence the activation of b1 integrins and their recruitment to adhesions. Cells were plated overnight on fibrillar collagen, stained with 9EG7 (a neo-epitope antibody that binds to activated b1 integrins) (Lenter et al., 1993) and analyzed by TIRF microscopy (Rajshankar et al., 2012). Compared with wild type, DDR1 over-expressing cells contained more adhesions with activated b1 integrins (Fig. 3A; P,0.01). "
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    ABSTRACT: Collagen degradation by phagocytosis is essential for physiological collagen turnover and connective tissue homeostasis. The rate limiting step of phagocytosis is the binding of specific adhesion receptors, which include the integrins and discoidin domain receptors (DDR), to fibrillar collagen. While previous data suggest that these two receptors interact, the functional nature of these interactions is not defined. In mouse and human fibroblasts we examined the effects of DDR1 knockdown and over-expression on β1 integrin subunit function. DDR1 expression levels were positively associated with enhanced contraction of floating and attached collagen gels, increased collagen binding and increased collagen remodeling. In DDR1 over-expressing cells compared with control cells, there were increased numbers, area and length of focal adhesions immunostained for talin, paxillin, vinculin and activated β1 integrin. After treatment with the integrin-cleaving protease jararhagin, in comparison to controls, DDR1 over-expressing cells exhibited increased β1 integrin cleavage at the cell membrane, indicating that DDR1 over-expression affected the access and susceptibility of cell-surface β1 integrin to the protease. DDR1 over-expression was associated with increased glycosylation of the β1 integrin subunit, which when blocked by deoxymannojirimycin, reduced collagen binding. Collectively these data indicate that DDR1 regulates β1 integrin interactions with fibrillar collagen, which positively impacts the binding step of collagen phagocytosis and collagen remodeling.
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    • "Immunostained cells were visualized by total internal reflection fluorescence (TIRF) microscopy (Leica Microsystems) at a Z-axis depth of 90 nm above the coverslip. The mean number and area of focal adhesions per cell were quantified with Leica MetaMorph software (>20 cells per condition) as described previously [21]. "
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