title: KSHV-TK is a tyrosine kinase that disrupts focal adhesions and induces Rho-mediated cell contraction.
abstract: Paradoxically, the thymidine kinase (TK) encoded by Kaposi sarcoma-associated herpesvirus (KSHV) is an extremely inefficient nucleoside kinase, when compared to TKs from related herpesviruses. We now show that KSHV-TK, in contrast to HSV1-TK, associates with the actin cytoskeleton and induces extensive cell contraction followed by membrane blebbing. These dramatic changes in cell morphology depend on the auto-phosphorylation of tyrosines 65, 85 and 120 in the N-terminus of KSHV-TK. Phosphorylation of tyrosines 65/85 and 120 results in an interaction with Crk family proteins and the p85 regulatory subunit of PI3-Kinase, respectively. The interaction of Crk with KSHV-TK leads to tyrosine phoshorylation of this cellular adaptor. Auto-phosphorylation of KSHV-TK also induces a loss of FAK and paxillin from focal adhesions, resulting in activation of RhoA-ROCK signalling to myosin II and cell contraction. In the absence of FAK or paxillin, KSHV-TK has no effect on focal adhesion integrity or cell morphology. Our observations demonstrate that by acting as a tyrosine kinase, KSHV-TK modulates signalling and cell morphology.
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK mbg22@cam.ac.uk.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Gill
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Turner
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK.
authors.forename: Philip G
authors.initials: PG
authors.lastname: Stevenson
authors.affiliation: Cell Motility Laboratory, London Research Institute Cancer Research UK, London, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Way
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D022001:Focal Adhesions / Q000201:enzymology* / Q000378:metabolism*; D006367:HeLa Cells; D019288:Herpesvirus 8, Human / Q000201:enzymology*; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D051419:Paxillin / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D050737:Proto-Oncogene Proteins c-crk / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D051419:Paxillin; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D050737:Proto-Oncogene Proteins c-crk; D020741:rho GTP-Binding Proteins; C485285:CRK protein, human
keywords: Crk/PI3‐Kinase; Kaposi sarcoma‐associated herpesvirus; RhoA; focal adhesion; thymidine kinase