The focal adhesion kinase amino-terminal domain localises to nuclei and intercellular junctions in HEK 293 and MDCK cells independently of tyrosine 397 and the carboxy-terminal domain.
The function and intracellular localisation of the non-catalytic NH(2)-terminal region of focal adhesion kinase (FAK) are unclear. We investigated the targetting of the FAK NH(2)-terminal domain in HEK 293 and epithelial MDCK cells. Exogenous expression of a variety of GFP-fused and epitope-tagged NH(2) terminal domain constructs either including or lacking the major Tyr 397 autophosphorylation and Src-binding site targeted to nuclei and cell-cell junctions in HEK 293 cells and co-localised at junctions with occludin, and beta1 integrin subunits at junctions. Mutation of Tyr 397 also had no effect on localisation of the NH(2)-terminal domain. In contrast, constructs encoding either the kinase or focal adhesion targeting (FAT) domains but lacking the NH(2)-terminal region failed to localise to intercellular junctions or nuclei. The NH(2)-terminal domain was not associated with beta1 integrin subunits as indicated by co-immunoprecipitation experiments, but did co-localise with cortical actin filaments. The NH(2)-terminal domain also targetted to nuclei and intercellular junctions in MDCK cells, whereas full-length FAK localised only to focal adhesions in these cells. These results indicate that the FAK NH(2)-terminal domain targets to epithelial intercellular junctions and nuclei and suggest novel functions for FAK NH(2)-terminal domain fragments independent of Y397, kinase, and FAT domains.
Stewart
Alasdair
A
Department of Medicine, University College London, The Rayne Building, 5 University Street, WC1E 6JJ, London, UK.
Ham
Claire
C
Zachary
Ian
I
D000199:Actins / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000378:metabolism; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D049452:Green Fluorescent Proteins; D006801:Humans; D007150:Immunohistochemistry; D019012:Integrin beta1 / Q000378:metabolism; D007365:Intercellular Junctions / Q000378:metabolism*; D008164:Luminescent Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D009154:Mutation; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry*; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry
D000199:Actins; D018076:DNA, Complementary; D019012:Integrin beta1; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human