Vasodilator-Stimulated Phosphoprotein Regulates Inside-Out Signaling of β2 Integrins in Neutrophils
Vasodilator-Stimulated Phosphoprotein Regulates Inside-Out Signaling of β2 Integrins in Neutrophils
复制标题
DOI：
10.4049/jimmunol.0903910
复制
发表时间：
2010-06-15
影响因子：
4.4
通讯作者：
Dib, Karim
中科院分区：
文献类型：
--
作者：
Deevi, Ravi K.;Koney-Dash, Madhuri;Dib, Karim
The monomeric GTPase Rap1 controls functional activation of beta(2) integrins in leukocytes. In this article, we describe a novel mechanism by which the chemoattractant fMLP activates Rap1 and inside-out signaling of b2 integrins. We found that fMLP-induced activation of Rap1 in human polymorphonuclear leukocytes or neutrophils and differentiated PLB-985 cells was blocked by inhibitors of the NO/guanosine-3',5'-cyclic monophosphate-dependent protein kinase (cGKI) pathway [N-(3-(aminomethyl) benzyl) acetamidine, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, DT-3 peptide, 8-(4-chlorophenylthio)guanosine 3',5'-cyclic monophosphothioate, Rp-isomer triethylammonium salt-guanosine-3',5'-cyclic monophosphate], indicating that the downstream signaling events in Rap1 activation involve the production of NO and guanosine-3',5'-cyclic monophosphate, as well as the activation of cGKI. Silencing the expression of vasodilator-stimulated phosphoprotein (VASP), a substrate of cGKI, in resting PLB-985 cells or mice neutrophils led to constitutive activation of Rap1. In parallel, silencing VASP in differentiated PLB-985 cells led to recruitment of C3G, a guanine nucleotide exchange factor for Rap1, to the plasma membrane. Expression of murine GFP-tagged phosphodeficient VASP Ser235Ala mutant (murine serine 235 of VASP corresponds to human serine 239) in PLB-985 cells blunted fMLP-induced translocation of C3G to the membrane and activation of Rap1. Thus, bacterial fMLP triggers cGKI-dependent phosphorylation of human VASP on serine 239 and, thereby, controls membrane recruitment of C3G, which is required for activation of Rap1 and b2 integrin-dependent antibacterial functions of neutrophils. The Journal of Immunology, 2010, 184: 6575-6584.
