title: RhoGDI-1 modulation of the activity of monomeric RhoGTPase RhoA regulates endothelial barrier function in mouse lungs.
abstract: Rho family GTPases have been implicated in the regulation of endothelial permeability via their actions on actin cytoskeletal organization and integrity of interendothelial junctions. In cell culture studies, activation of RhoA disrupts interendothelial junctions and increases endothelial permeability, whereas activation of Rac1 and Cdc42 enhances endothelial barrier function by promoting the formation of restrictive junctions. The primary regulators of Rho proteins, guanine nucleotide dissociation inhibitors (GDIs), form a complex with the GDP-bound form of the Rho family of monomeric G proteins, and thus may serve as a nodal point regulating the activation state of RhoGTPases. In the present study, we addressed the in vivo role of RhoGDI-1 in regulating pulmonary microvascular permeability using RhoGDI-1(-/-) mice. We observed that basal endothelial permeability in lungs of RhoGDI-1(-/-) mice was 2-fold greater than wild-type mice. This was the result of opening of interendothelial junctions in lung microvessels which are normally sealed. The activity of RhoA (but not of Rac1 or Cdc42) was significantly increased in RhoGDI-1(-/-) lungs as well as in cultured endothelial cells on downregulation of RhoGDI-1 with siRNA, consistent with RhoGDI-1-mediated modulation RhoA activity. Thus, RhoGDI-1 by repressing RhoA activity regulates lung microvessel endothelial barrier function in vivo. In this regard, therapies augmenting endothelial RhoGDI-1 function may be beneficial in reestablishing the endothelial barrier and lung fluid balance in lung inflammatory diseases such as acute respiratory distress syndrome.
authors.affiliation: University of Illinois College of Medicine, Department of Pharmacology, 835 S. Wolcott Ave, Chicago, IL 60612, USA.
authors.forename: Matvey
authors.initials: M
authors.lastname: Gorovoy
authors.forename: Radu
authors.initials: R
authors.lastname: Neamu
authors.forename: Jiaxin
authors.initials: J
authors.lastname: Niu
authors.forename: Stephen
authors.initials: S
authors.lastname: Vogel
authors.forename: Dan
authors.initials: D
authors.lastname: Predescu
authors.forename: Jun
authors.initials: J
authors.lastname: Miyoshi
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Takai
authors.forename: Vidisha
authors.initials: V
authors.lastname: Kini
authors.forename: Dolly
authors.initials: D
authors.lastname: Mehta
authors.forename: Asrar B
authors.initials: AB
authors.lastname: Malik
authors.forename: Tatyana
authors.initials: T
authors.lastname: Voyno-Yasenetskaya
mesh_terms: D000818:Animals; D015824:Blood-Air Barrier / Q000201:enzymology* / Q000503:physiopathology; D002199:Capillary Permeability / Q000235:genetics; D042783:Endothelial Cells / Q000201:enzymology / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000201:enzymology* / Q000502:physiology; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008168:Lung / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D008171:Lung Diseases / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology; D051379:Mice; D018345:Mice, Knockout; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D020730:Guanine Nucleotide Dissociation Inhibitors; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein