title: IQGAP1 regulates endothelial barrier function via EB1-cortactin cross talk.
abstract: Cross talk between the actin cytoskeleton and microtubules (MT) has been implicated in the amplification of agonist-induced Rho signaling, leading to increased vascular endothelial permeability. This study tested the involvement of actin-MT cross talk in the mechanisms of barrier enhancement induced by hepatocyte growth factor (HGF) and evaluated the role of the adaptor protein IQGAP1 in integrating the MT- and actin-dependent pathways of barrier enhancement. IQGAP1 knockdown by small interfering RNA attenuated the HGF-induced increase in endothelial barrier properties and abolished HGF-activated cortical actin dynamics. IQGAP1 reduction abolished HGF-induced peripheral accumulation of Rac cytoskeletal effector cortactin and cortical actin remodeling. In addition, HGF stimulated peripheral MT growth in an IQGAP1-dependent fashion. HGF also induced Rac1-dependent IQGAP1 association with the MT fraction and the formation of a protein complex containing end-binding protein 1 (EB1), IQGAP1, and cortactin. Decreasing endogenous IQGAP1 abolished HGF-induced EB1-cortactin colocalization at the cell periphery. In turn, expression of IQGAP1ΔC (IQGAP1 lacking the C-terminal domain) attenuated the cortactin association with EB1 and suppressed HGF-induced endothelial cell peripheral actin cytoskeleton enhancement. These results demonstrate for the first time the MT-actin cross talk mechanism of HGF-induced endothelial barrier enhancement and suggest that IQGAP1 functions as a hub linking HGF-induced signaling to MT and actin remodeling via EB1-IQGAP1-cortactin interactions.
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, Illinois, USA.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, Illinois, USA.
authors.forename: Xinyong
authors.initials: X
authors.lastname: Tian
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, Illinois, USA.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Gawlak
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, Illinois, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: O'Donnell
authors.affiliation: Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: David B
authors.initials: DB
authors.lastname: Sacks
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, Illinois, USA abirukov@medicine.bsd.uchicago.edu.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Birukova
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D051356:Cortactin / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D034741:RNA, Small Interfering; D015398:Signal Transduction; D020703:ras GTPase-Activating Proteins / Q000378:metabolism*
chemical_list: C495868:CTTN protein, human; D051356:Cortactin; C066855:HGF protein, human; C101203:IQ motif containing GTPase activating protein 1; C500985:MAPRE1 protein, human; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; D020703:ras GTPase-Activating Proteins; D017228:Hepatocyte Growth Factor