title: Novel aspects of Kindlin-3 function in humans based on a new case of leukocyte adhesion deficiency III.
abstract: BACKGROUND
  Kindlin-3 is a novel integrin activator in hematopoietic cells, and its deficiency leads to immune problems and severe bleeding, known as leukocyte adhesion deficiency III (LAD-III). Our current understanding of Kindlin-3 function primarily relies on analysis of animal models or cell lines.
  
  
  OBJECTIVE
  To understand the functions of Kindlin-3 in human primary blood cells.
  
  
  METHODS
  We analyzed primary and immortalized hematopoietic cells obtained from a new LAD-III patient with immune problems, bleeding, a history of anemia, and abnormally shaped red blood cells.
  
  
  RESULTS
  The patient's white blood cells (WBCs) and platelets showed defects in agonist-induced integrin activation and botrocetin-induced platelet agglutination. Primary leukocytes from this patient exhibited abnormal activation of β(1) integrin. Integrin activation defects were responsible for the observed deficiency in the botrocetin-induced platelet response. Analysis of patient genomic DNA revealed a novel mutation in the Kindlin3 gene. The mutation abolished Kindlin-3 expression in primary WBCs and platelets, owing to abnormal splicing. Kindlin-3 is expressed in red blood cells (RBCs), and its deficiency is proposed to lead to abnormally shaped RBCs. Immortalized patient WBCs expressed a truncated form of Kindlin-3 that was not sufficient to support integrin activation. Expression of Kindlin-3 cDNA in immortalized patient WBCs rescued integrin activation defects, whereas overexpression of the truncated form did not.
  
  
  CONCLUSIONS
  Kindlin-3 deficiency impairs integrin function, including activation of β(1) integrin. Abnormalities in glycoprotein Ib-IX function in Kindlin-3-deficient platelets are secondary to integrin defects. The region of Kindlin-3 encoded by exon 11 is crucial for its ability to activate integrins in humans.
authors.affiliation: Department of Molecular Cardiology, Joseph J Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: J
authors.initials: J
authors.lastname: Meller
authors.forename: N L
authors.initials: NL
authors.lastname: Malinin
authors.forename: S
authors.initials: S
authors.lastname: Panigrahi
authors.forename: B A
authors.initials: BA
authors.lastname: Kerr
authors.forename: A
authors.initials: A
authors.lastname: Patil
authors.forename: Y
authors.initials: Y
authors.lastname: Ma
authors.forename: L
authors.initials: L
authors.lastname: Venkateswaran
authors.forename: I B
authors.initials: IB
authors.lastname: Rogozin
authors.forename: N
authors.initials: N
authors.lastname: Mohandas
authors.forename: M S
authors.initials: MS
authors.lastname: Ehlayel
authors.forename: E A
authors.initials: EA
authors.lastname: Podrez
authors.forename: J
authors.initials: J
authors.lastname: Chinen
authors.forename: T V
authors.initials: TV
authors.lastname: Byzova
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D015153:Blotting, Western; D002460:Cell Line; D002648:Child; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D047468:Immunoprecipitation; D018370:Leukocyte-Adhesion Deficiency Syndrome / Q000503:physiopathology*; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D000906:Antibodies; C477322:FERMT3 protein, human; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger