The small Rho GTPase Rif and actin cytoskeletal remodelling

2012 ◽  
Vol 40 (1) ◽  
pp. 268-272 ◽  
Author(s):  
Lifei Fan ◽  
Harry Mellor
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpase ◽  
Active Form ◽  
Present Review ◽  
Gtpase Domain ◽  
Domain Structures ◽  
Downstream Effectors ◽  
Inactive Form ◽  
The Family ◽  
Recent Addition

The Rif GTPase is a recent addition to small Rho GTPase family; it shares low homology with other members in the family and evolutionarily parallels with the development of vertebrates. Rif has the conserved Rho GTPase domain structures and cycles between a GDP-bound inactive form and a GTP-bound active form. In its active form, Rif signals through multiple downstream effectors. In the present review, our aim is to summarize the current information about the Rif effectors and how Rif remodels actin cytoskeleton in many aspects.

WAVE signalling: from biochemistry to biology

2006 ◽  
Vol 34 (1) ◽  
pp. 73-76 ◽  
Author(s):  
S.H. Soderling ◽  
J.D. Scott
Keyword(s):  
Cell Division ◽  
Actin Cytoskeleton ◽  
Rho Gtpase ◽  
Current Knowledge ◽  
Biological Significance ◽  
Molecular Switches ◽  
Small Gtpases ◽  
Present Review ◽  
Cellular Targets ◽  
Syndrome Protein

The small GTPases Rho, Rac and Cdc42 (cell-division cycle 42) function as molecular switches to modulate the actin cytoskeleton. They achieve this by modulating the activity of downstream cellular targets. One group of Rho GTPase effectors, WAVE (Wiskott–Aldrich syndrome protein verprolin homologous)-1, WAVE-2 and WAVE-3, function as scaffolds for actin-based signalling complexes. The present review highlights current knowledge regarding the biochemistry of the WAVE signalling complexes and their biological significance.

scholarly journals MAP1B Regulates Axonal Development by Modulating Rho-GTPase Rac1 Activity

2010 ◽  
Vol 21 (20) ◽  
pp. 3518-3528 ◽  
Author(s):  
Carolina Montenegro-Venegas ◽  
Elena Tortosa ◽  
Silvana Rosso ◽  
Diego Peretti ◽  
Flavia Bollati ◽  
...  
Keyword(s):  
Rho Gtpase ◽  
Active Form ◽  
Axon Growth ◽  
Growth Defect ◽  
Nucleotide Exchange ◽  
Axonal Development ◽  
Nucleotide Exchange Factor ◽  
Downstream Effectors ◽  
Rac1 Activity ◽  
Reduced Rate

Cultured neurons obtained from MAP1B-deficient mice have a delay in axon outgrowth and a reduced rate of axonal elongation compared with neurons from wild-type mice. Here we show that MAP1B deficiency results in a significant decrease in Rac1 and cdc42 activity and a significant increase in Rho activity. We found that MAP1B interacted with Tiam1, a guanosine nucleotide exchange factor for Rac1. The decrease in Rac1/cdc42 activity was paralleled by decreases in the phosphorylation of the downstream effectors of these proteins, such as LIMK-1 and cofilin. The expression of a constitutively active form of Rac1, cdc42, or Tiam1 rescued the axon growth defect of MAP1B-deficient neurons. Taken together, these observations define a new and crucial function of MAP1B that we show to be required for efficient cross-talk between microtubules and the actin cytoskeleton during neuronal polarization.

Conducting and Superhydrophobic Hybrid 2D Material from Coronene and Pyrene

2021 ◽  
Author(s):  
Jyothibabu Sajila Arya ◽  
Malay Krishna Mahato ◽  
Sethuraman Sankararaman ◽  
Prasad Edamana
Keyword(s):  
Structural Stability ◽  
2D Material ◽  
The Family ◽  
Potential Applications ◽  
Recent Addition

Graphdiyne, a recent addition to the family of 2D covalent organic nanosheet structure, is known for its structural stability and potential applications in catalysis, sensors, electronics and optoelectronics. Design and...

Cytokinesis arrest and redistribution of actin-cytoskeleton regulatory components in cells expressing the Rho GTPase CDC42Hs

1996 ◽  
Vol 109 (2) ◽  
pp. 367-377 ◽  
Author(s):  
H. Dutartre ◽  
J. Davoust ◽  
J.P. Gorvel ◽  
P. Chavrier
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpases ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Rho Gtpase ◽  
Laser Scanning Microscopy ◽  
Regulatory Subunit ◽  
Confocal Laser ◽  
Complex Architectures ◽  
Immunofluorescence Labelling

In mammalian cells, Rho GTPases control the reorganisation of the actin cytoskeleton in response to growth factors. In the cytoplasm, the polymerisation of actin filaments and their organisation into complex architectures is orchestrated by numerous proteins which act either directly, by interacting with actin, or by producing secondary messengers which serve as mediators between signal transduction pathways and the microfilament organisation. We sought to determine whether the intracellular distribution of some of these regulatory components may be controlled by the Rho GTPase CDC42Hs. With this aim, we have established HeLa-derived human cell lines in which expression of a constitutively activated mutant of CDC42Hs is inducible. Morphological analysis by immunofluorescence labelling and confocal laser scanning microscopy revealed a massive reorganisation of F-actin in cortical microspikes as well as podosome-like structures located at the ventral face of the cells. Concomitantly, the cells became giant and multinucleate indicating that cytokinesis was impaired. The actin bundling protein T-plastin, the vasodilatator-stimulated phosphoprotein (VASP), a profilin ligand, as well as the 85 kDa regulatory subunit of the phosphoinosite 3-kinase redistributed with F-actin into the CDC42Hs-induced structures.

scholarly journals Polarized Distribution of IQGAP Proteins in Gastric Parietal Cells and Their Roles in Regulated Epithelial Cell Secretion

2003 ◽  
Vol 14 (3) ◽  
pp. 1097-1108 ◽  
Author(s):  
Rihong Zhou ◽  
Zhen Guo ◽  
Charles Watson ◽  
Emily Chen ◽  
Rong Kong ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Actin Cytoskeleton ◽  
Acid Secretion ◽  
Rho Gtpase ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Parietal Cells ◽  
Actin Dynamics ◽  
Cell Secretion ◽  
Gastric Parietal Cells

Actin cytoskeleton plays an important role in the establishment of epithelial cell polarity. Cdc42, a member of Rho GTPase family, modulates actin dynamics via its regulators, such as IQGAP proteins. Gastric parietal cells are polarized epithelial cells in which regulated acid secretion occurs in the apical membrane upon stimulation. We have previously shown that actin isoforms are polarized to different membrane domains and that the integrity of the actin cytoskeleton is essential for acid secretion. Herein, we show that Cdc42 is preferentially distributed to the apical membrane of gastric parietal cells. In addition, we revealed that two Cdc42 regulators, IQGAP1 and IQGAP2, are present in gastric parietal cells. Interestingly, IQGAP2 is polarized to the apical membrane of the parietal cells, whereas IQGAP1 is mainly distributed to the basolateral membrane. An IQGAP peptide that competes with full-length IQGAP proteins for Cdc42-binding in vitro also inhibits acid secretion in streptolysin-O-permeabilized gastric glands. Furthermore, this peptide disrupts the association of IQGAP and Cdc42 with the apical actin cytoskeleton and prevents the apical membrane remodeling upon stimulation. We propose that IQGAP2 forms a link that associates Cdc42 with the apical cytoskeleton and thus allows for activation of polarized secretion in gastric parietal cells.

The atypical Rho GTPase RhoD is a regulator of actin cytoskeleton dynamics and directed cell migration

2017 ◽  
Vol 352 (2) ◽  
pp. 255-264 ◽  
Author(s):  
Magdalena Blom ◽  
Katarina Reis ◽  
Johan Heldin ◽  
Johan Kreuger ◽  
Pontus Aspenström
Keyword(s):  
Cell Migration ◽  
Actin Cytoskeleton ◽  
Rho Gtpase ◽  
Directed Cell Migration ◽  
Cytoskeleton Dynamics

Absence of Activation in Vitro of Renin in Rat Plasma

1982 ◽  
Vol 62 (4) ◽  
pp. 435-437 ◽  
Author(s):  
M. H. De Keijzer ◽  
A. P. Provoost ◽  
F. H. M. Derkx
Keyword(s):  
Human Plasma ◽  
Active Form ◽  
Plasma Renin ◽  
Rat Plasma ◽  
Plasma Renin Concentration ◽  
Inactive Form ◽  
Inactive Renin

1. Rat plasma was subjected at 4°C to various treatments known to convert inactive renin into its active form in human plasma. 2. No statistical differences in plasma renin concentration were found when the levels after the various treatments were compared with that of untreated rat plasma. 3. It is concluded that, in contrast to human plasma, no inactive form of renin is present in rat plasma.

G alpha(i-2) mediates renal LLC-PK1 growth by a Raf-independent activation of p42/p44 MAP kinase

1997 ◽  
Vol 272 (2) ◽  
pp. F273-F282 ◽  
Author(s):  
T. B. Kinane ◽  
I. Kang ◽  
A. Chu ◽  
S. H. Chin ◽  
L. Ercolani
Keyword(s):  
Cell Growth ◽  
Protein Kinases ◽  
Doubling Time ◽  
Active Form ◽  
Renal Cells ◽  
Downstream Effectors ◽  
Mitogen Activated Protein ◽  
Cell Doubling Time ◽  
Cell Growth And Differentiation ◽  
Maximal Expression

The protooncogene G alpha(i-2) plays a pivotal role in signaling pathways that control renal cell growth and differentiation. Mitogen-activated protein kinases (MAPKs) are potential downstream effectors for G alpha(i-2) in these pathways. In predifferentiated LLC-PK1 renal cells, the temporal maximal expression of G alpha(i-2) coincided with maximal activation of MAPK(p42/p44). By contrast, pertussis toxin treatment of these cells inhibited cell growth and reduced MAPK(p42/p44) activity by 30%. These findings reflected upstream activation of MAPK kinase (MEK1), as transient transfection of cells with a plasmid encoding a constitutively active form of MEK1 increased MAPK(p42/p44) activity and cell growth, whereas treatment with PD-098059, an inhibitor of MEK1 activity, reduced MAPK(p42/p44) activity and cell growth. Expression of a guanosinetriphosphatase (GTPase)-deficient G alpha(i-2) in these cells increased MAPK(p42/p44) activity and correspondingly reduced cell doubling time from 24 to 10 h without altering the activity of Raf-1 or c-Jun/stress-activated protein kinases (SAPKs). By contrast, expression of a GTPase-deficient G alpha(i-3) in these cells reduced both their cell doubling time by 30% and MAPK(p42/p44) activity by 60%. As the known MEKK isoforms (MEKK1, -2, and -3) can also activate SAPKs, these findings suggest the GTP-charged G alpha(i-2) subunit transduces growth signals in renal cells via activation of MAPK(p42/p44) and that such activation may be linked to pathways containing novel MEKK isoforms that preferentially activate MEKs.

ON DIFFERENT MOLECULAR EORMS OE PLASMINOGEN ACTIVATOR INHIBITOR

1987 ◽  
Author(s):  
I Carlsson ◽  
J Chmielewska ◽  
B Wiman
Keyword(s):  
Conditioned Medium ◽  
Plasminogen Activator ◽  
Active Form ◽  
Sodium Dodecyl ◽  
Calf Serum ◽  
Gel Filtration ◽  
Plasminogen Activator Inhibitor ◽  
Elution Pattern ◽  
Inactive Form ◽  
Activator Inhibitor

The production of plasminogen activator inhibitor (PAI) by the human cell-lines Hep G2 and HT 1080 have been studied by immunochemical and functional methods. In conditioned medium collected after 2h, the PAI seemed to be almost fully active, but with increasing incubation time the activity was gradually lost, in spite of that the PAI-antigen content increased continously. The active PAI form can be separated from the inactive form by gel-filtration. The inactive form behaves as a low Mr (about 50,000) component in the absence and in the presence of sodium dodecyl-sulphate. In contrast, the active form of PAI behaves as a high Mr (>300,000) compound in the absence of sodium dodecylsulphate but as a low MT compound in its presence. The low M_r inactive PAI has been purified to homogeneity from HT 1080 conditioned medium, collected in the absence of fetal calf serum. This was achieved by chromatography on Concanavalin A-Sepharose, gel-filtration on Sephacryl S-300 and affinity chromatography on insolubilized monoclonal antibodies against PA-inhibitor. On treatment of this form of the inhibitor with 4 mol/L Guanidinium chloride, the activity was regained, but its gel-filtration behaviour was unchanged in the absence of serum/plasma (Mr about 50,000). Addition of plasma or serum prior to the gel-filtration, changed the elution pattern of PAI towards a high Mr form. The reason for this behaviour is not yet fully understood, but the most plausible explanation is the presence of a high Mr PAI-binding protein in plasma/serum. This hypothesis is presently being explored .

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