Integrin-linked kinase is an essential link between integrins and uptake of bacterial pathogens by epithelial cells

Authors

  • Beinan Wang,

    Corresponding author
    1. Department of Microbiology, Medical School, University of Minnesota, 1460 Mayo Memorial Building, MMC 196, 420 Delaware Street SE., Minneapolis, MN 55455, USA.
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  • Ryan S. Yurecko,

    1. Department of Microbiology, Medical School, University of Minnesota, 1460 Mayo Memorial Building, MMC 196, 420 Delaware Street SE., Minneapolis, MN 55455, USA.
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  • Shoukat Dedhar,

    1. BC Cancer Research Center and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada, V5Z 1L3.
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  • P. Patrick Cleary

    1. Department of Microbiology, Medical School, University of Minnesota, 1460 Mayo Memorial Building, MMC 196, 420 Delaware Street SE., Minneapolis, MN 55455, USA.
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*E-mail beinan@mail.ahc.umn.edu; Tel. (+1) 612 624 9966; Fax (+1) 612 626 0623.

Summary

Entry of Streptococcus pyogenes or group A streptococcus (GAS) into host cells is mediated by fibronectin bound to surface proteins, M1 or PrtF1, forming a bridge to α5β1 integrins. This interaction leads to cytoskeletal rearrangement and uptake of streptococci. We postulated that integrin-linked kinase (ILK), which directly associates with integrins, is the universal link between integrins and several bacterial pathogens. We showed that inhibition of ILK expression by siRNA silencing, or ILK kinase activity by chemical inhibitors or expression of a dominant negative form of ILK reduced M1-mediated invasion of epithelial cells up to 80%. To evaluate the ILK requirement for PrtF1-mediated GAS invasion, a M1PrtF1+ recombinant strain within the M1 background was constructed. Inhibition of ILK kinase activity also significantly reduced invasion of epithelial cells by this recombinant and wild-type strain JRS4 that expresses PrtF1. In addition, impaired ILK kinase activity results in significant reduction of integrin-dependent invasion mediated by invasins of two other important pathogens, Staphylococcus aureus and Yersinia spp. This study suggests that bacterial pathogens evolved different molecules and strategies to exploit the host integrin signalling pathway for their survival.

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