title: Nuclear localization and apoptotic regulation of an amino-terminal domain focal adhesion kinase fragment in endothelial cells.
abstract: This study investigated the subcellular compartmentalization of focal adhesion kinase (FAK) fragments and their regulation during apoptosis of human umbilical vein endothelial cells. A 50 kDa NH(2)-terminal FAK fragment and a 120 kDa FAK variant were constitutively expressed and specifically found in the nuclear fraction of cells, while a 55 kDa COOH-terminal FAK fragment was only in the cytosolic fraction. FAK cleavage fragments generated during apoptosisremained in the cytosol, while p120FAK and p50 NH(2)-terminal FAK remained in the nuclear compartment. The caspase inhibitor, ZVAD-fmk, prevented the apoptosis-induced proteolysis of p125 and p120FAK, generation of the 80 kDa cleavage product, and increased expression of p50N-FAK. Western blot with phospho-specific FAK showed that nuclear p125(FAK) was phosphorylated at a significant level at Y861, while FAK phosphorylated at Y397 and Y407 was largely in the cytosol. These results indicate that FAK NH(2)- and COOH-terminal domain fragments are segregated between nuclear and cytosolic compartments in endothelial cells and suggest novel functions for the FAK NH(2)-terminal domain.
authors.affiliation: Department of Medicine, University College London, 5 University Street, London, WC1E 6JJ, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Lobo
authors.forename: I
authors.initials: I
authors.lastname: Zachary
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D017209:Apoptosis; D015153:Blotting, Western; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D020287:In Situ Nick-End Labeling; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry* / Q000378:metabolism*; D019311:Staurosporine / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: D061945:Caspase Inhibitors; D010446:Peptide Fragments; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D020169:Caspases; D019311:Staurosporine