title: Kindlin-2 directly binds actin and regulates integrin outside-in signaling.
abstract: Reduced levels of kindlin-2 (K2) in endothelial cells derived from K2(+/-)mice or C2C12 myoblastoid cells treated with K2 siRNA showed disorganization of their actin cytoskeleton and decreased spreading. These marked changes led us to examine direct binding between K2 and actin. Purified K2 interacts with F-actin in cosedimentation and surface plasmon resonance analyses and induces actin aggregation. We further find that the F0 domain of K2 binds actin. A mutation, LK(47)/AA, within a predicted actin binding site (ABS) of F0 diminishes its interaction with actin by approximately fivefold. Wild-type K2 and K2 bearing the LK(47)/AA mutation were equivalent in their ability to coactivate integrin αIIbβ3 in a CHO cell system when coexpressed with talin. However, K2-LK(47)/AA exhibited a diminished ability to support cell spreading and actin organization compared with wild-type K2. The presence of an ABS in F0 of K2 that influences outside-in signaling across integrins establishes a new foundation for considering how kindlins might regulate cellular responses.
authors.affiliation: Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Kamila
authors.initials: K
authors.lastname: Bledzka
authors.affiliation: Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Bialkowska
authors.affiliation: Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Khalid
authors.initials: K
authors.lastname: Sossey-Alaoui
authors.affiliation: Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Julia
authors.initials: J
authors.lastname: Vaynberg
authors.affiliation: Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195.
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Pluskota
authors.affiliation: Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 plowe@ccf.org qinj@ccf.org.
authors.forename: Jun
authors.initials: J
authors.lastname: Qin
authors.affiliation: Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 plowe@ccf.org qinj@ccf.org.
authors.forename: Edward F
authors.initials: EF
authors.lastname: Plow
mesh_terms: D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D016466:CHO Cells; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D003412:Cricetulus; D003598:Cytoskeletal Proteins / Q000378:metabolism; D006367:HeLa Cells; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000378:metabolism*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000502:physiology*; D016608:Talin / Q000378:metabolism
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; C477322:FERMT3 protein, human; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D016608:Talin