title: A fundamental role of mAbp1 in neutrophils: impact on beta(2) integrin-mediated phagocytosis and adhesion in vivo.
abstract: The mammalian actin-binding protein 1 (mAbp1, Hip-55, SH3P7) is phosphorylated by the nonreceptor tyrosine kinase Syk that has a fundamental effect for several beta(2) integrin (CD11/CD18)-mediated neutrophil functions. Live cell imaging showed a dynamic enrichment of enhanced green fluorescence protein-tagged mAbp1 at the phagocytic cup of neutrophil-like differentiated HL-60 cells during beta(2) integrin-mediated phagocytosis of serum-opsonized Escherichia coli. The genetic absence of Syk or its pharmacologic inhibition using piceatannol abrogated the proper localization of mAbp1 at the phagocytic cup. The genetic absence or down-regulation of mAbp1 using the RNA interference technique significantly compromised beta(2) integrin-mediated phagocytosis of serum-opsonized E coli or Salmonella typhimurium in vitro as well as clearance of S typhimurium infection in vivo. Moreover, the genetic absence of mAbp1 almost completely abrogated firm neutrophil adhesion under physiologic shear stress conditions in vitro as well as leukocyte adhesion and extravasation in inflamed cremaster muscle venules of mice treated with tumor-necrosis factor alpha. Functional analysis showed that the down-regulation of mAbp1 diminished the number of beta(2) integrin clusters in the high-affinity conformation under flow conditions. These unanticipated results define mAbp1 as a novel molecular player in integrin biology that is critical for phagocytosis and firm neutrophil adhesion under flow conditions.
authors.affiliation: Walter Brendel Centre for Experimental Medicine, Ludwig-Maximilians-University Munich, D-80336 Munich, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schymeinsky
authors.forename: Ronald
authors.initials: R
authors.lastname: Gerstl
authors.forename: Ingrid
authors.initials: I
authors.lastname: Mannigel
authors.forename: Katy
authors.initials: K
authors.lastname: Niedung
authors.forename: David
authors.initials: D
authors.lastname: Frommhold
authors.forename: Klaus
authors.initials: K
authors.lastname: Panthel
authors.forename: Jürgen
authors.initials: J
authors.lastname: Heesemann
authors.forename: Michael
authors.initials: M
authors.lastname: Sixt
authors.forename: Thomas
authors.initials: T
authors.lastname: Quast
authors.forename: Waldemar
authors.initials: W
authors.lastname: Kolanus
authors.forename: Attila
authors.initials: A
authors.lastname: Mocsai
authors.forename: Jürgen
authors.initials: J
authors.lastname: Wienands
authors.forename: Markus
authors.initials: M
authors.lastname: Sperandio
authors.forename: Barbara
authors.initials: B
authors.lastname: Walzog
mesh_terms: D000818:Animals; D018821:CD18 Antigens / Q000502:physiology*; D002448:Cell Adhesion / Q000502:physiology; D004926:Escherichia coli / Q000472:pathogenicity; D018922:HL-60 Cells; D006801:Humans; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D008840:Microfilament Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D009504:Neutrophils / Q000502:physiology*; D010587:Phagocytosis / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D017452:Receptors, IgG / Q000378:metabolism; D012486:Salmonella typhimurium / Q000472:pathogenicity; D000072377:Syk Kinase; D018909:src Homology Domains / Q000235:genetics / Q000502:physiology*
chemical_list: D018821:CD18 Antigens; C485512:Dbnl protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008840:Microfilament Proteins; D017452:Receptors, IgG; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; C000606897:Syk protein, mouse