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p85-RhoGDI2, a novel complex, is required for PSGL-1-induced β1 integrin-mediated lymphocyte adhesion to VCAM-1.

Abstract
P-selectin glycoprotein ligand-1 and β1 integrin play essential roles in T cell trafficking during inflammation. E-selectin and vascular cell adhesion molecule-1 are their ligands expressed on inflammation-activated endothelium. During the tethering and rolling of lymphocytes on endothelium, P-selectin glycoprotein ligand-1 binds E-selectin and induces signals. Subsequently, β1 integrin is activated and mediates stable adhesion. However, the intracellular signal pathways from PSGL-1 to β1 integrin have not yet been fully understood. Here, we find that p85, a regulatory subunit of phosphoinositide 3-kinase, forms a novel complex with Rho-GDP dissociation inhibitor-2, a lymphocyte-specific RhoGTPases dissociation inhibitor. Phosporylations of the p85-bound Rho-GDP dissociation inhibitor-2 on 130 and 153 tyrosine residues by c-Abl and Src were required for the complex to be recruited to P-selectin glycoprotein ligand-1 and thereby regulate β1 integrin-mediated T cell adhesion to vascular cell adhesion molecule-1. Both shRNAs to Rho-GDP dissociation inhibitor-2 and p85 and over-expression of Rho-GDP dissociation inhibitor-2 Y130F and Y153F significantly reduced the above-mentioned adhesion. Although Rho-GDP dissociation inhibitor-2 in the p85-Rho-GDP dissociation inhibitor-2 complex was also phosphorylated on 24 tyrosine residue by Syk, the phosphorylation is not required for the adhesion. Taken together, we find that specific phosphorylations on 130 and 153 tyrosine residues of p85-bound Rho-GDP dissociation inhibitor-2 are pivotal for P-selectin glycoprotein ligand-1-induced β1 integrin-mediated lymphocyte adhesion to vascular cell adhesion molecule-1. This will shed new light on the mechanisms that connect leukocyte initial rolling with subsequent adhesion.
AuthorsJixian Luo, Tingshuang Xu, Chunfeng Li, Xueqing Ba, Xiaoguang Wang, Yong Jiang, Xianlu Zeng
JournalThe international journal of biochemistry & cell biology (Int J Biochem Cell Biol) Vol. 45 Issue 12 Pg. 2764-73 (Dec 2013) ISSN: 1878-5875 [Electronic] Netherlands
PMID24055812 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
CopyrightCopyright © 2013 Elsevier Ltd. All rights reserved.
Chemical References
  • Integrin beta1
  • Membrane Glycoproteins
  • P-selectin ligand protein
  • Vascular Cell Adhesion Molecule-1
  • rho Guanine Nucleotide Dissociation Inhibitor beta
  • Phosphatidylinositol 3-Kinases
Topics
  • Cell Adhesion (physiology)
  • Cell Movement (physiology)
  • Humans
  • Integrin beta1 (metabolism)
  • Jurkat Cells
  • Leukocyte Rolling (physiology)
  • Lymphocytes (cytology, metabolism)
  • Membrane Glycoproteins (genetics, metabolism)
  • Phosphatidylinositol 3-Kinases (metabolism)
  • Phosphorylation
  • Signal Transduction
  • Transfection
  • Vascular Cell Adhesion Molecule-1 (metabolism)
  • rho Guanine Nucleotide Dissociation Inhibitor beta (metabolism)

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