scholarly journals Rap1, AF6 and Pak4 cooperate with Par3 to promote ZA assembly and remodeling in the fly photoreceptor

2017 ◽  
Author(s):  
Rhian F. Walther ◽  
Mubarik Burki ◽  
Noelia Pinal ◽  
Clare Rogerson ◽  
Franck Pichaud
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Binding Protein ◽  
Small Gtpase ◽  
Actin Binding ◽  
Cell Morphogenesis ◽  
Recruitment And Retention ◽  
Actin Binding Protein ◽  
P21 Activated Kinase ◽  
Fly Photoreceptor

AbstractThe epithelial Zonula adherens (ZA) is a main adhesion compartment that enables organogenesis by allowing epithelial cells to assemble into sheets. How ZA assembly is regulated during epithelial cell morphogenesis is not fully understood. We show that during ZA morphogenesis, the function of the small GTPase Rap1 and the F-actin binding protein AF6/Cno are both linked to that of the P21-activated kinase Pak4/Mbt. We find that Rap1 and Mbt regulate each other’s localization at the ZA and cooperate in promoting ECadherin stabilization. During this process Cno regulates the recruitment of Baz at the ZA, a process that is also regulated by Arm phosphorylation by Mbt. Altogether, we propose that Rap1, Cno and Mbt regulate ZA morphogenesis by coordinating ECadherin stabilization and Baz recruitment and retention. In addition, our work uncovers a new link between two main oncogenes, Rap1 and Pak4/Mbt, in a model developing epithelial cell.

Cdc42/Rac1-dependent activation of the p21-activated kinase (PAK) regulates human platelet lamellipodia spreading: implication of the cortical-actin binding protein cortactin

Blood ◽  
2002 ◽  
Vol 100 (13) ◽  
pp. 4462-4469 ◽  
Author(s):  
Catherine Vidal ◽  
Blandine Geny ◽  
Josiane Melle ◽  
Martine Jandrot-Perrus ◽  
Michaëla Fontenay-Roupie
Keyword(s):  
Shape Change ◽  
Binding Protein ◽  
Actin Binding ◽  
Cortical Actin ◽  
Toxin B ◽  
Actin Reorganization ◽  
Actin Binding Protein ◽  
Direct Binding ◽  
P21 Activated Kinase ◽  
The Relationship

Platelet activation by thrombin or thrombin receptor-activating peptide (TRAP) results in extensive actin reorganization that leads to filopodia emission and lamellae spreading concomitantly with activation of the Rho family small G proteins, Cdc42 and Rac1. Evidence has been provided that direct binding of Cdc42-guanosine triphosphate (GTP) and Rac1-GTP to the N-terminal regulatory domain of the p21-activated kinase (PAK) stimulates PAK activation and actin reorganization. In the present study, we have investigated the relationship between shape change and PAK activation. We show that thrombin, TRAP, or monoclonal antibody (MoAb) anti-FcγRIIA IV.3 induces an activation of Cdc42 and Rac1. The GpVI ligand, convulxin (CVX), that forces platelets to lamellae spreading efficiently activates Rac1. Thrombin, TRAP, MoAb IV.3, and CVX stimulate autophosphorylation and kinase activity of PAK. Inhibition of Cdc42 and Rac1 with clostridial toxin B inhibits PAK activation and lamellae spreading. The cortical-actin binding protein, p80/85 cortactin, is constitutively associated with PAK in resting platelets and dissociates from PAK after thrombin stimulation. Inhibition of PAK autophosphorylation by toxin B prevents the dissociation of cortactin. These results suggest that Cdc42/Rac1-dependent activation of PAK may trigger early platelet shape change, at least in part through the regulation of cortactin binding to PAK.

Identification of a Homolog of Actin-Binding Protein, ABP-280, Localized at Epithelial Cell-Cell Boundaries in Hydra

1999 ◽  
Vol 16 (3) ◽  
pp. 439-443
Author(s):  
Masayuki Hatta ◽  
Masahiko Sakaguchi ◽  
Yoshitaka Kobayakawa ◽  
Yasuyuki Kishimoto ◽  
Osamu Koizumi
Keyword(s):  
Epithelial Cell ◽  
Binding Protein ◽  
Actin Binding ◽  
Actin Binding Protein ◽  
Cell Cell

Identification of actin-binding protein and villin in toad bladder epithelia

1984 ◽  
Vol 246 (1) ◽  
pp. F101-F104
Author(s):  
D. A. Ausiello ◽  
H. L. Corwin ◽  
J. H. Hartwig
Keyword(s):  
Epithelial Cell ◽  
Gel Electrophoresis ◽  
Binding Protein ◽  
Cell Structure ◽  
Toad Bladder ◽  
Actin Binding ◽  
Cross Linking ◽  
Actin Binding Protein ◽  
Calcium Dependent ◽  
Cell Extracts

Two actin-modulating proteins, actin-binding protein and villin, have been identified and functionally characterized in toad bladder epithelial cells. A 270-kdalton protein from bladder epithelial extracts 1) cross-reacts with antibodies to purified toad oocyte or rabbit macrophage actin-binding protein and comigrates with these proteins on gel electrophoresis, 2) contains all of the actin filament cross-linking activity found in epithelial cell extracts, and 3) its activity is calcium insensitive. A 95-kdalton protein from the same extracts 1) cross-reacts with antibodies to purified toad oocyte villin and comigrates with purified villin from the oocyte and chicken intestine on polyacrylamide gels, and 2) is capable of decreasing the viscosity of actin solutions only in the presence of calcium. These proteins offer potential sites for calcium-dependent and -independent regulation of toad bladder epithelial cell structure.

Sea urchin egg villin: identification of villin in a non-epithelial cell from an invertebrate species

1991 ◽  
Vol 100 (1) ◽  
pp. 61-71 ◽  
Author(s):  
F.S. Wang ◽  
E.M. Bonder
Keyword(s):  
Epithelial Cell ◽  
Sea Urchin ◽  
Brush Border ◽  
Actin Filaments ◽  
Binding Protein ◽  
Actin Binding ◽  
Villin Headpiece ◽  
Actin Binding Protein ◽  
Sea Urchin Eggs ◽  
Sea Urchin Egg

Fertilization of sea urchin eggs results in the rapid polymerization of actin filaments and subsequent formation of a brush border-like cortical cytoskeleton. A 110 × 10(3) Mr (110K) actin binding protein has been purified from extracts of unfertilized Strongylocentrotus purpuratus eggs. Analysis of polymerization kinetics using fluorescence and viscometry assays demonstrated that 110K accelerated the nucleation phase of actin assembly only in the presence of elevated Ca2+. The Ca(2+)-mediated effects were correlated with a decrease in sedimentable polymer and a decrease in average filament length. Addition of Ca2+ to solutions of 110K and F-actin, polymerized in the presence of EGTA, resulted in a precipitous drop in viscosity and the decreased viscosity was fully reversible upon chelation of Ca2+. The Ca2+ threshold for 110K activation was in the 10(−6) to 10(−7) M range. Nucleated assembly experiments using Limulus sperm acrosomal processes demonstrated that egg 110K capped the barbed ends of actin filaments. In the absence of Ca2+, 110K organized actin filaments into bundles at pH values less than 7.4. Anti-egg 110K antibody crossreacted with chicken intestinal epithelial cell villin and anti-porcine villin headpiece monoclonal antibody crossreacted with 110K. Further, 110K possesses an approximately 10 × 10(3) Mr terminal polypeptide segment that is immunologically related to villin headpiece. These studies demonstrate that sea urchin egg 110K is functionally, immunologically and structurally related to villin, an actin binding protein expressed in specific epithelial tissues in vertebrates. Consequently, this finding provides insight into the potential mechanisms that might determine the genesis of the cortical brush border cytoarchitecture in sea urchin eggs and further sheds light on the evolution of the villin protein family.

scholarly journals In vivo dynamics of the F-actin-binding protein neurabin-II

2000 ◽  
Vol 345 (2) ◽  
pp. 185-194 ◽  
Author(s):  
David J. STEPHENS ◽  
George BANTING
Keyword(s):  
Cell Body ◽  
Actin Filaments ◽  
Fluorescent Protein ◽  
Binding Protein ◽  
Cytochalasin D ◽  
Small Gtpase ◽  
Actin Binding ◽  
Rhodamine Phalloidin ◽  
Actin Binding Protein

Neurabin-II (spinophilin) is a ubiquitously expressed F-actin-binding protein containing an N-terminal actin-binding domain, a PDZ (PSD95/discs large/ZO-1) domain and a C-terminal domain predicted to form a coiled-coil structure. We have stably expressed a green fluorescent protein (GFP)-tagged version of neurabin-II in PC12 cells, and characterized the in vivo dynamics of this actin-binding protein using confocal fluorescence microscopy. We show that GFP-neurabin-II localizes to actin filaments, especially at cortical sites and areas underlying sites of active membrane remodelling. GFP-neurabin-II labels only a subset of F-actin within these cells, as indicated by rhodamine-phalloidin staining. Both actin filaments and small, highly motile structures within the cell body are seen. Photobleaching experiments show that GFP-neurabin-II also exhibits highly dynamic behaviour when bound to actin filaments. Latrunculin B treatment results in rapid relocalization of GFP-neurabin-II to the cytosol, whereas cytochalasin D treatment causes the collapse of GFP-neurabin-II fluorescence to intensely fluorescent foci of F-actin within the cell body. This collapse is reversed on cytochalasin D removal, recovery from which is greatly accelerated by stimulation of cells with epidermal growth factor (EGF). Furthermore, we show that this EGF-induced relocalization of GFP-neurabin-II is dependent on the activity of the small GTPase Rac1 but not the activity of ADP-ribosylation factor 6.

Clathrin Hub Expression Dissociates the Actin-Binding Protein Hip1R from Coated Pits and Disrupts Their Alignment with the Actin Cytoskeleton

Traffic ◽  
2001 ◽  
Vol 2 (11) ◽  
pp. 851-858 ◽  
Author(s):  
Elizabeth M. Bennett ◽  
Chih-Ying Chen ◽  
Asa E. Y. Engqvist-Goldstein ◽  
David G. Drubin ◽  
Frances M. Brodsky
Keyword(s):  
Actin Cytoskeleton ◽  
Binding Protein ◽  
Actin Binding ◽  
Coated Pits ◽  
Actin Binding Protein

Binding of Human Platelet Glycoprotein lb and Actin to Fragments of Actin-Binding Protein

1992 ◽  
Vol 67 (02) ◽  
pp. 252-257 ◽  
Author(s):  
Anne M Aakhus ◽  
J Michael Wilkinson ◽  
Nils Olav Solum
Keyword(s):  
Actin Filaments ◽  
High Speed ◽  
Binding Protein ◽  
Protein A ◽  
Actin Binding ◽  
Platelet Glycoprotein ◽  
Actin Binding Protein ◽  
Crossed Immunoelectrophoresis ◽  
Triton X ◽  
Calpain Inhibitors

SummaryActin-binding protein (ABP) is degraded into fragments of 190 and 90 kDa by calpain. A monoclonal antibody (MAb TI10) against the 90 kDa fragment of ABP coprecipitated with the glycoprotein lb (GP lb) peak observed on crossed immunoelectrophoresis of Triton X-100 extracts of platelets prepared without calpain inhibitors. MAb PM6/317 against the 190 kDa fragment was not coprecipitated with the GP lb peak under such conditions. The 90 kDa fragment was adsorbed on protein A agarose from extracts that had been preincubated with antibodies to GP lb. This supports the idea that the GP Ib-ABP interaction resides in the 90 kDa region of ABP. GP lb was sedimented with the Triton-insoluble actin filaments in trace amounts only, and only after high speed centrifugation (100,000 × g, 3 h). Both the 190 kDa and the 90 kDa fragments of ABP were sedimented with the Triton-insoluble actin filaments.

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