title: Neutrophil beta2 integrin inhibition by enhanced interactions of vasodilator-stimulated phosphoprotein with S-nitrosylated actin.
abstract: Production of reactive species in neutrophils exposed to hyperoxia causes S-nitrosylation of β-actin, which increases formation of short actin filaments, leading to alterations in the cytoskeletal network that inhibit β(2) integrin-dependent adherence (Thom, S. R., Bhopale, V. M., Mancini, D. J., and Milovanova, T. N. (2008) J. Biol. Chem. 283, 10822-10834). In this study, we found that vasodilator-stimulated protein (VASP) exhibits high affinity for S-nitrosylated short filamentous actin, which increases actin polymerization. VASP bundles Rac1, Rac2, cyclic AMP-dependent, and cyclic GMP-dependent protein kinases in close proximity to short actin filaments, and subsequent Rac activation increases actin free barbed end formation. Using specific chemical inhibitors or reducing cell concentrations of any of these proteins with small inhibitory RNA abrogates enhanced free barbed end formation, increased actin polymerization, and β(2) integrin inhibition by hyperoxia. Alternatively, incubating neutrophils with formylmethionylleucylphenylalanine or 8-bromo-cyclic GMP activates either cyclic AMP-dependent or cyclic GMP-dependent protein kinase, respectively, outside of the short F-actin pool and phosphorylates VASP on serine 153. Phosphorylated VASP abrogates the augmented polymerization normally observed with S-nitrosylated actin, VASP binding to actin, elevated Rac activity, and elevated formation of actin free barbed ends, thus restoring normal β(2) integrin function.
authors.affiliation: Institute for Environmental Medicine, Department of Emergency Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA. sthom@mail.med.upenn.edu
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Thom
authors.forename: Veena M
authors.initials: VM
authors.lastname: Bhopale
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.forename: Marina
authors.initials: M
authors.lastname: Bogush
authors.forename: Shaohui
authors.initials: S
authors.lastname: Huang
authors.forename: Tatyana N
authors.initials: TN
authors.lastname: Milovanova
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D018821:CD18 Antigens / Q000235:genetics / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D000199:Actins; D018821:CD18 Antigens; D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D000098662:Vasodilator-Stimulated Phosphoprotein; C016276:8-bromocyclic GMP; D009240:N-Formylmethionine Leucyl-Phenylalanine; D011494:Protein Kinases; D006152:Cyclic GMP