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RNAi Library Screening Reveals Gβ1, Casein Kinase 2α and ICAP-1 as Novel Regulators of LFA-1-mediated T-cell Polarity and Migration
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  • Michael Freeley,
  • Antje Hoff,
  • Eugene Dempsey,
  • Dara Dunican,
  • Emily Bennett,
  • Anthony Davies,
  • Dermot Kelleher,
  • Aideen Long
Michael Freeley
Dublin City University

Corresponding Author:[email protected]

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Antje Hoff
Trinity College
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Eugene Dempsey
Trinity College
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Dara Dunican
Dublin City University
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Emily Bennett
Trinity College
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Anthony Davies
Trinity College
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Dermot Kelleher
The University of British Columbia Faculty of Medicine
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Aideen Long
Trinity College
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Abstract

The αLβ2 integrin LFA-1 plays a key role in T-cell adhesion to the endothelial vasculature and migration into both secondary lymphoid organs and peripheral tissues via interactions with its target protein ICAM-1, but the pathways that regulate LFA-1-mediated T-cell polarity and migration are not fully understood. In this study we screened two RNAi libraries targeting G protein-coupled receptors (GPCR)/GPCR-associated proteins and kinases in a HuT-78 T-cell line model of LFA-1-stimulated T cell migration. Based on staining of the actin cytoskeleton, multiple parameters to measure cell morphology were used to assess the contribution of 1109 genes to LFA-1-mediated T cell polarity and migration. These RNAi screens identified a number of both novel and previously identified genes that either increased or decreased the polarity and migratory capacity of these cells. Following multiparametric analysis, hierarchical clustering and pathway analysis, three of these genes were characterised in further detail using primary human T-cells, revealing novel roles for the heterotrimeric G protein subunit Gβ1 and casein kinase 2 in LFA-1-mediated T-cell polarity and migration in-vitro. Our studies also highlighted a new role for ICAP-1, an adaptor protein previously described to be associated with β1 integrins, in β2 integrin LFA-1-directed migration in T-cells. Knockdown of ICAP-1 expression in primary T cells revealed a role in cell polarity, cell velocity and transmigration towards SDF-1 for this adaptor protein. This study therefore uncovers new roles for GPCR/GPCR-associated proteins and kinases in T-cell migration and provides potential novel targets for modulation of the T-cell immune response
Submitted to Immunology & Cell Biology
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