title: Plexin-B2 negatively regulates macrophage motility, Rac, and Cdc42 activation.
abstract: Plexins are cell surface receptors widely studied in the nervous system, where they mediate migration and morphogenesis though the Rho family of small GTPases. More recently, plexins have been implicated in immune processes including cell-cell interaction, immune activation, migration, and cytokine production. Plexin-B2 facilitates ligand induced cell guidance and migration in the nervous system, and induces cytoskeletal changes in overexpression assays through RhoGTPase. The function of Plexin-B2 in the immune system is unknown. This report shows that Plexin-B2 is highly expressed on cells of the innate immune system in the mouse, including macrophages, conventional dendritic cells, and plasmacytoid dendritic cells. However, Plexin-B2 does not appear to regulate the production of proinflammatory cytokines, phagocytosis of a variety of targets, or directional migration towards chemoattractants or extracellular matrix in mouse macrophages. Instead, Plxnb2(-/-) macrophages have greater cellular motility than wild type in the unstimulated state that is accompanied by more active, GTP-bound Rac and Cdc42. Additionally, Plxnb2(-/-) macrophages demonstrate faster in vitro wound closure activity. Studies have shown that a closely related family member, Plexin-B1, binds to active Rac and sequesters it from downstream signaling. The interaction of Plexin-B2 with Rac has only been previously confirmed in yeast and bacterial overexpression assays. The data presented here show that Plexin-B2 functions in mouse macrophages as a negative regulator of the GTPases Rac and Cdc42 and as a negative regulator of basal cell motility and wound healing.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
authors.forename: Kelly E
authors.initials: KE
authors.lastname: Roney
authors.forename: Brian P
authors.initials: BP
authors.lastname: O'Connor
authors.forename: Haitao
authors.initials: H
authors.lastname: Wen
authors.forename: Eda K
authors.initials: EK
authors.lastname: Holl
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Guthrie
authors.forename: Beckley K
authors.initials: BK
authors.lastname: Davis
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Jones
authors.forename: Sushmita
authors.initials: S
authors.lastname: Jha
authors.forename: Lisa
authors.initials: L
authors.lastname: Sharek
authors.forename: Rafael
authors.initials: R
authors.lastname: Garcia-Mata
authors.forename: James E
authors.initials: JE
authors.lastname: Bear
authors.forename: Jenny P-Y
authors.initials: JP
authors.lastname: Ting
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000378:metabolism; D002465:Cell Movement; D017690:Cell Transplantation / Q000379:methods; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010587:Phagocytosis; D011485:Protein Binding; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D016207:Cytokines; D009419:Nerve Tissue Proteins; C519231:Plxnb2 protein, mouse; D017493:Leukocyte Common Antigens; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein