scholarly journals Rho family GTP binding proteins are involved in the regulatory volume decrease process in NIH3T3 mouse fibroblasts

2002 ◽  
Vol 541 (3) ◽  
pp. 779-796 ◽  
Author(s):  
Stine F. Pedersen ◽  
Kristine H. Beisner ◽  
Charlotte Hougaard ◽  
Berthe M. Willumsen ◽  
Ian H. Lambert ◽  
...  
Keyword(s):  
Binding Proteins ◽  
Regulatory Volume Decrease ◽  
Mouse Fibroblasts ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family ◽  
Volume Decrease

Interaction of G protein Gβγ dimers with small GTP-binding proteins of the Rho family

FEBS Letters ◽  
1996 ◽  
Vol 399 (3) ◽  
pp. 211-214 ◽  
Author(s):  
Rainer Harhammer ◽  
Antje Gohla ◽  
Günter Schultz
Keyword(s):  
G Protein ◽  
Binding Proteins ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family

Regulation of cell volume and intracellular pH in hyposmotically swollen rat osteosarcoma cells

1995 ◽  
Vol 73 (7-8) ◽  
pp. 535-544 ◽  
Author(s):  
C. Lo ◽  
J. Ferrier ◽  
H. C. Tenenbaum ◽  
C. A. G. McCulloch
Keyword(s):  
Cell Volume ◽  
Intracellular Ph ◽  
Binding Proteins ◽  
Kinase Inhibitor ◽  
Regulatory Volume Decrease ◽  
Cell Swelling ◽  
Osteosarcoma Cells ◽  
Extracellular Medium ◽  
Gtp Binding Proteins ◽  
Gtp Binding

The maintenance of cell volume involves transduction of a volume-sensing signal into effectors of volume-regulatory transporters. After exposure to anisotonic conditions, cells undergo compensatory volume changes that are mediated by active transport and passive movement of ions and solutes. Intracellular pH (pHi) homeostasis may be compromised during these processes. We have studied pHi and some of the signal transduction mechanisms involved in the regulatory volume decrease (RVD) that occurs after exposure to hypoosmolar conditions in rat osteosarcoma cells, ROS 17/2.8. Cells were loaded with BCECF; pHi and cell volume were estimated by dual excitation ratio fluorimetry. Swelling of cells in 4-(2-hydroxyethyl)-l-piperazineethanesulfonic acid (HEPES) buffered hypotonic medium induced a rapid cell swelling followed by an incomplete RVD of ~30% in suspended (i.e., round) cells and ~60% in attached (i.e., spread) cells that was independent of subpassage number. RVD was inhibited by ouabain, valinomycin, and high external [K+], all of which should reduce the cell membrane electrochemical gradient for K+. Inhibition of RVD was induced also by decreasing intracellular [Ca2+] with B APTA–AM and by depletion of Cl−, indicating the role of calcium-regulated K+ and Cl− efflux during RVD. Depolymerization of actin filaments by cytochalasin D prolonged the RVD three-fold and nonspecific activation of GTP-binding proteins up-regulated RVD. In attached cells the hypoosmolar-induced swelling caused a large reduction in pHi (~0.7 units), which was sustained as long as cells were in hypoosmotic medium. The reduction of pHi induced by cell swelling was inhibited by Na+-free extracellular medium, ouabain, the tyrosine kinase inhibitor genistein, and to a lesser extent by Cl−-free medium. However, amiloride failed to inhibit the hypoosmolar-induced reduction of pHi. Collectively these data indicate that RVD of ROS 17/2.8 cells in HEPES-buffered medium is dependent on conductive efflux of K+ and Cl− that is regulated by cell shape, actin, and GTP-binding proteins. The sustained inhibition of pHi homeostasis induced by cell swelling may reflect the existence of cell volume sensing mechanisms that operate through tyrosine kinases to regulate pHi.Key words: cell volume, pH, osteoblast, G proteins, actin.

Rho family small GTP-binding proteins in growth cone signalling

1997 ◽  
Vol 7 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Liqun Luo ◽  
Lily Y Jan ◽  
Yuh-Nung Jan
Keyword(s):  
Growth Cone ◽  
Binding Proteins ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family

scholarly journals Rac GTPase interacts specifically with phosphatidylinositol 3-kinase

1996 ◽  
Vol 315 (3) ◽  
pp. 775-779 ◽  
Author(s):  
Gary M. BOKOCH ◽  
Chris J. VLAHOS ◽  
Yan WANG ◽  
Ulla G. KNAUS ◽  
Alexis E. TRAYNOR-KAPLAN
Keyword(s):  
Growth Factor ◽  
Actin Polymerization ◽  
Binding Proteins ◽  
Specific Interaction ◽  
Bound State ◽  
Rac Gtpase ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family

The Rac GTP-binding proteins are members of the Rho family and regulate growth factor-stimulated actin assembly in a variety of cells. The formation of phosphorylated inositol lipids has been implicated in control of the processes initiating and regulating such actin polymerization. Associations of Rho family GTP-binding proteins with enzymes involved in lipid metabolism have been described. Here we demonstrate a direct and specific interaction of Rac proteins with phosphatidylinositol (PI) 3-kinase. This interaction is dependent upon Rac being in a GTP-bound state and requires an intact Rac effector domain. In contrast, direct binding of RhoA to PI 3-kinase could not be detected. Rac–GTP also bound to PI 3-kinase in Swiss 3T3 fibroblast and human neutrophil lysates, and increased PI 3-kinase activity became associated with Rac–GTP in platelet-derived growth factor-stimulated cells. Interaction of Rac–GTP with PI 3-kinase in vitro stimulated the activity of the enzyme by 2–9-fold. A specific interaction of active Rac with PI 3-kinase might be important in regulation of the actin cytoskeleton.

scholarly journals A novel member of the rho family of small GTP-binding proteins is specifically required for cytokinesis.

1996 ◽  
Vol 133 (6) ◽  
pp. 1321-1329 ◽  
Author(s):  
D A Larochelle ◽  
K K Vithalani ◽  
A De Lozanne
Keyword(s):  
Binding Proteins ◽  
Molecular Genetic ◽  
Genetic Screen ◽  
Phenotypic Characterization ◽  
Essential Requirement ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Subcellular Processes ◽  
Rho Family

Several members of the rho/rac family of small GTP-binding proteins are known to regulate the distribution of the actin cytoskeleton in various subcellular processes. We describe here a novel rac protein, racE, which is specifically required for cytokinesis, an actomyosin-mediated process. The racE gene was isolated in a molecular genetic screen devised to isolate genes required for cytokinesis in Dictyostelium. Phenotypic characterization of racE mutants revealed that racE is not essential for any other cell motility event, including phagocytosis, chemotaxis, capping, or development. Our data provide the first genetic evidence for the essential requirement of a rho-like protein, specifically in cytokinesis, and suggest a role for these proteins in coordinating cytokinesis with the mitotic events of the cell cycle.

Small GTP-Binding Proteins of the Rho Family in the Dictyostelium Cytoskeleton

Protist ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Francisco Rivero ◽  
Angelika A. Noegel
Keyword(s):  
Binding Proteins ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family

scholarly journals Association of the Rho family small GTP-binding proteins with Rho GDP dissociation inhibitor (Rho GDI) in Saccharomyces cerevisiae

Oncogene ◽  
1997 ◽  
Vol 15 (4) ◽  
pp. 417-422 ◽  
Author(s):  
Gertrude Koch ◽  
Kazuma Tanaka ◽  
Tadayuki Masuda ◽  
Wataru Yamochi ◽  
Hidetaro Nonaka ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Binding Proteins ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family ◽  
Gdp Dissociation Inhibitor
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