scholarly journals The C-terminus SH3-binding domain of Kv1.3 is required for the actin-mediated immobilization of the channel via cortactin

2015 ◽  
Vol 26 (9) ◽  
pp. 1640-1651 ◽  
Author(s):  
Peter Hajdu ◽  
Geoffrey V. Martin ◽  
Ameet A. Chimote ◽  
Orsolya Szilagyi ◽  
Koichi Takimoto ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
Actin Polymerization ◽  
Actin Dynamics ◽  
Actin Network ◽  
Immune Synapse ◽  
Proximity Ligation ◽  
C Terminus ◽  
Kv1.3 Channels ◽  
And Migration ◽  
Channel Polarization

Kv1.3 channels play a pivotal role in the activation and migration of T-lymphocytes. These functions are accompanied by the channels' polarization, which is essential for associated downstream events. However, the mechanisms that govern the membrane movement of Kv1.3 channels remain unclear. F-actin polymerization occurs concomitantly to channel polarization, implicating the actin cytoskeleton in this process. Here we show that cortactin, a factor initiating the actin network, controls the membrane mobilization of Kv1.3 channels. FRAP with EGFP-tagged Kv1.3 channels demonstrates that knocking down cortactin decreases the actin-based immobilization of the channels. Using various deletion and mutation constructs, we show that the SH3 motif of Kv1.3 mediates the channel immobilization. Proximity ligation assays indicate that deletion or mutation of the SH3 motif also disrupts interaction of the channel with cortactin. In T-lymphocytes, the interaction between HS1 (the cortactin homologue) and Kv1.3 occurs at the immune synapse and requires the channel's C-terminal domain. These results show that actin dynamics regulates the membrane motility of Kv1.3 channels. They also provide evidence that the SH3 motif of the channel and cortactin plays key roles in this process.

scholarly journals Changes in Vasodilator-Stimulated Phosphoprotein Phosphorylation, Profilin-1, and Cofilin-1 in Accreta and Protection by DHA

2018 ◽  
Vol 26 (6) ◽  
pp. 757-765 ◽  
Author(s):  
Mehboob Ali ◽  
Lynette K. Rogers ◽  
Kathryn M. Heyob ◽  
Catalin S. Buhimschi ◽  
Irina A. Buhimschi
Keyword(s):  
Actin Polymerization ◽  
Cellular Proliferation ◽  
Placenta Accreta ◽  
Gestational Trophoblastic Disease ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Migration And Invasion ◽  
Aberrant Expression ◽  
Vasp Phosphorylation ◽  
And Migration

Accreta and gestational trophoblastic disease (ie, choriocarcinoma) are placental pathologies characterized by hyperproliferative and invasive trophoblasts. Cellular proliferation, migration, and invasion are heavily controlled by actin-binding protein (ABP)-mediated actin dynamics. The ABP vasodilator-stimulated phosphoprotein (VASP) carries key regulatory role. Profilin-1, cofilin-1, and VASP phosphorylated at Ser157 (pVASP-S157) and Ser239 (pVASP-S239) are ABPs that regulate actin polymerization and stabilization and facilitate cell metastases. Docosahexaenoic acid (DHA) inhibits cancer cell migration and proliferation. We hypothesized that analogous to malignant cells, ABPs regulate these processes in extravillous trophoblasts (EVTs), which exhibit aberrant expression in placenta accreta. Placental–myometrial junction biopsies of histologically confirmed placenta accreta had significantly increased immunostaining levels of cofilin-1, VASP, pVASP-S239, and F-actin. Treatment of choriocarcinoma-derived trophoblast (BeWo) cells with DHA (30 µM) for 24 hours significantly suppressed proliferation, migration, and pVASP-S239 levels and altered protein profiles consistent with increased apoptosis. We concluded that in accreta changes in the ABP expression profile were a response to restore homeostasis by counteracting the hyperproliferative and invasive phenotype of the EVT. The observed association between VASP phosphorylation, apoptosis, and trophoblast proliferation and migration suggest that DHA may offer a therapeutic solution for conditions where EVT is hyperinvasive.

Withaferin A binds covalently to the N-terminal domain of annexin A2

2012 ◽  
Vol 393 (10) ◽  
pp. 1151-1163 ◽  
Author(s):  
Gabriel Ozorowski ◽  
Christopher M. Ryan ◽  
Julian P. Whitelegge ◽  
Hartmut Luecke
Keyword(s):  
Actin Polymerization ◽  
Inhibitory Effect ◽  
Annexin A2 ◽  
Actin Dynamics ◽  
Withaferin A ◽  
Core Domain ◽  
Cancer Pathways ◽  
Terminal Domain ◽  
C Terminus

Abstract Annexin A2 (AnxA2), a 38-kDa member of the Ca2+-binding annexin family, has been implicated in numerous cancer pathways. Withaferin A (WithfA), a natural plant compound, has been reported previously to bind covalently to Cys133 of the AnxA2 core domain leading to a reduction of the invasive capabilities of cancer cells by altering their cytoskeleton. We show here that AnxA2 has an inhibitory effect on actin polymerization, and a modification with WithfA significantly increases this inhibitory role of AnxA2. Using mass spectrometry and single-site mutants, we localized the WithfA-AnxA2 interaction to the N-terminal domain of AnxA2 where WithfA binds covalently to Cys9. Whereas binding to F-actin filaments has been mapped to the C terminus of AnxA2, our results suggest that the N-terminal domain modified by WithfA may also play a role in the AnxA2-actin interaction. The binding of WithfA may regulate the AnxA2-mediated actin dynamics in two distinct ways: (i) the increase of F-actin bundling activity by the Anx2/p11 heterotetramer and (ii) the decrease of actin polymerization as a result of the increased affinity of AnxA2 to the barbed end of actin microfilaments. We demonstrate the susceptibility of Cys9 of AnxA2 to chemical modifications and exclude Cys133 as a binding site for WithfA.

scholarly journals Profilin connects actin assembly with microtubule dynamics

2016 ◽  
Vol 27 (15) ◽  
pp. 2381-2393 ◽  
Author(s):  
Michaela Nejedla ◽  
Sara Sadi ◽  
Vadym Sulimenko ◽  
Francisca Nunes de Almeida ◽  
Hans Blom ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Actin Dynamics ◽  
Control Element ◽  
Actin Assembly ◽  
Actin Nucleation ◽  
Superresolution Microscopy ◽  
Drug Treatments ◽  
And Migration ◽  
Wasp Family Proteins ◽  
Microscopy Techniques

Profilin controls actin nucleation and assembly processes in eukaryotic cells. Actin nucleation and elongation promoting factors (NEPFs) such as Ena/VASP, formins, and WASP-family proteins recruit profilin:actin for filament formation. Some of these are found to be microtubule associated, making actin polymerization from microtubule-associated platforms possible. Microtubules are implicated in focal adhesion turnover, cell polarity establishment, and migration, illustrating the coupling between actin and microtubule systems. Here we demonstrate that profilin is functionally linked to microtubules with formins and point to formins as major mediators of this association. To reach this conclusion, we combined different fluorescence microscopy techniques, including superresolution microscopy, with siRNA modulation of profilin expression and drug treatments to interfere with actin dynamics. Our studies show that profilin dynamically associates with microtubules and this fraction of profilin contributes to balance actin assembly during homeostatic cell growth and affects micro­tubule dynamics. Hence profilin functions as a regulator of microtubule (+)-end turnover in addition to being an actin control element.

scholarly journals Abi2-Deficient Mice Exhibit Defective Cell Migration, Aberrant Dendritic Spine Morphogenesis, and Deficits in Learning and Memory

2004 ◽  
Vol 24 (24) ◽  
pp. 10905-10922 ◽  
Author(s):  
Matthew Grove ◽  
Galina Demyanenko ◽  
Asier Echarri ◽  
Patricia A. Zipfel ◽  
Marisol E. Quiroz ◽  
...  
Keyword(s):  
Cell Migration ◽  
Dendritic Spine ◽  
Actin Polymerization ◽  
Adherens Junctions ◽  
Actin Dynamics ◽  
Long Term Memory ◽  
Cell Morphogenesis ◽  
And Migration

ABSTRACT The Abl-interactor (Abi) family of adaptor proteins has been linked to signaling pathways involving the Abl tyrosine kinases and the Rac GTPase. Abi proteins localize to sites of actin polymerization in protrusive membrane structures and regulate actin dynamics in vitro. Here we demonstrate that Abi2 modulates cell morphogenesis and migration in vivo. Homozygous deletion of murine abi2 produced abnormal phenotypes in the eye and brain, the tissues with the highest Abi2 expression. In the absence of Abi2, secondary lens fiber orientation and migration were defective in the eye, without detectable defects in proliferation, differentiation, or apoptosis. These phenotypes were consistent with the localization of Abi2 at adherens junctions in the developing lens and at nascent epithelial cell adherens junctions in vitro. Downregulation of Abi expression by RNA interference impaired adherens junction formation and correlated with downregulation of the Wave actin-nucleation promoting factor. Loss of Abi2 also resulted in cell migration defects in the neocortex and hippocampus, abnormal dendritic spine morphology and density, and severe deficits in short- and long-term memory. These findings support a role for Abi2 in the regulation of cytoskeletal dynamics at adherens junctions and dendritic spines, which is critical for intercellular connectivity, cell morphogenesis, and cognitive functions.

scholarly journals Cofilin-mediated actin dynamics promotes actin bundle formation during Drosophila bristle development

2016 ◽  
Vol 27 (16) ◽  
pp. 2554-2564 ◽  
Author(s):  
Jing Wu ◽  
Heng Wang ◽  
Xuan Guo ◽  
Jiong Chen
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Model System ◽  
Actin Dynamics ◽  
Actin Network ◽  
Loss Of Function ◽  
Actin Bundle ◽  
Actin Bundles

The actin bundle is an array of linear actin filaments cross-linked by actin-bundling proteins, but its assembly and dynamics are not as well understood as those of the branched actin network. Here we used the Drosophila bristle as a model system to study actin bundle formation. We found that cofilin, a major actin disassembly factor of the branched actin network, promotes the formation and positioning of actin bundles in the developing bristles. Loss of function of cofilin or AIP1, a cofactor of cofilin, each resulted in increased F-actin levels and severe defects in actin bundle organization, with the defects from cofilin deficiency being more severe. Further analyses revealed that cofilin likely regulates actin bundle formation and positioning by the following means. First, cofilin promotes a large G-actin pool both locally and globally, likely ensuring rapid actin polymerization for bundle initiation and growth. Second, cofilin limits the size of a nonbundled actin-myosin network to regulate the positioning of actin bundles. Third, cofilin prevents incorrect assembly of branched and myosin-associated actin filament into bundles. Together these results demonstrate that the interaction between the dynamic dendritic actin network and the assembling actin bundles is critical for actin bundle formation and needs to be closely regulated.

scholarly journals Discovery of functional interactions among actin regulators by analysis of image fluctuations in an unperturbed motile cell system

2018 ◽  
Vol 373 (1747) ◽  
pp. 20170110 ◽  
Author(s):  
Tadamoto Isogai ◽  
Gaudenz Danuser
Keyword(s):  
Cell Biology ◽  
Live Cell Imaging ◽  
Actin Polymerization ◽  
Cell Imaging ◽  
Cell System ◽  
Feedback Loops ◽  
Actin Dynamics ◽  
Actin Network ◽  
Theme Issue ◽  
Functional Interactions

Cell migration is driven by propulsive forces derived from polymerizing actin that pushes and extends the plasma membrane. The underlying actin network is constantly undergoing adaptation to new mechano-chemical environments and intracellular conditions. As such, mechanisms that regulate actin dynamics inherently contain multiple feedback loops and redundant pathways. Given the highly adaptable nature of such a system, studies that use only perturbation experiments (e.g. knockdowns, overexpression, pharmacological activation/inhibition, etc.) are challenged by the nonlinearity and redundancy of the pathway. In these pathway configurations, perturbation experiments at best describe the function(s) of a molecular component in an adapting (e.g. acutely drug-treated) or fully adapted (e.g. permanent gene silenced) cell system, where the targeted component now resides in a non-native equilibrium. Here, we propose how quantitative live-cell imaging and analysis of constitutive fluctuations of molecular activities can overcome these limitations. We highlight emerging actin filament barbed-end biology as a prime example of a complex, nonlinear molecular process that requires a fluctuation analytic approach, especially in an unperturbed cellular system, to decipher functional interactions of barbed-end regulators, actin polymerization and membrane protrusion. This article is part of the theme issue ‘Self-organization in cell biology’.

scholarly journals Differential interactions of the formins INF2, mDia1, and mDia2 with microtubules

2011 ◽  
Vol 22 (23) ◽  
pp. 4575-4587 ◽  
Author(s):  
Jeremie Gaillard ◽  
Vinay Ramabhadran ◽  
Emmanuelle Neumanne ◽  
Pinar Gurel ◽  
Laurent Blanchoin ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Actin Polymerization ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Differential Function ◽  
Cellular Processes ◽  
High Affinity ◽  
C Terminus ◽  
Molecular Machinery ◽  
Cytoskeletal Elements

A number of cellular processes use both microtubules and actin filaments, but the molecular machinery linking these two cytoskeletal elements remains to be elucidated in detail. Formins are actin-binding proteins that have multiple effects on actin dynamics, and one formin, mDia2, has been shown to bind and stabilize microtubules through its formin homology 2 (FH2) domain. Here we show that three formins, INF2, mDia1, and mDia2, display important differences in their interactions with microtubules and actin. Constructs containing FH1, FH2, and C-terminal domains of all three formins bind microtubules with high affinity (Kd < 100 nM). However, only mDia2 binds microtubules at 1:1 stoichiometry, with INF2 and mDia1 showing saturating binding at approximately 1:3 (formin dimer:tubulin dimer). INF2-FH1FH2C is a potent microtubule-bundling protein, an effect that results in a large reduction in catastrophe rate. In contrast, neither mDia1 nor mDia2 is a potent microtubule bundler. The C-termini of mDia2 and INF2 have different functions in microtubule interaction, with mDia2's C-terminus required for high-affinity binding and INF2's C-terminus required for bundling. mDia2's C-terminus directly binds microtubules with submicromolar affinity. These formins also differ in their abilities to bind actin and microtubules simultaneously. Microtubules strongly inhibit actin polymerization by mDia2, whereas they moderately inhibit mDia1 and have no effect on INF2. Conversely, actin monomers inhibit microtubule binding/bundling by INF2 but do not affect mDia1 or mDia2. These differences in interactions with microtubules and actin suggest differential function in cellular processes requiring both cytoskeletal elements.

scholarly journals VASP mediated actin dynamics activate and recruit a filopodia myosin

2021 ◽  
Author(s):  
Ashley L Arthur ◽  
Amy Crawford ◽  
Anne Houdusse ◽  
Margaret A Titus
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
The State ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Actin Network ◽  
Cortical Actin ◽  
Close Collaboration ◽  
Actin Binding Protein ◽  
Dynamic Regions

Filopodia are thin, actin-based structures that cells use to interact with their environments. Filopodia initiation requires a suite of conserved proteins but the mechanism remains poorly understood. The actin polymerase VASP and a MyTH-FERM (MF) myosin, DdMyo7 in amoeba, are essential for filopodia initiation. DdMyo7 is localized to dynamic regions of the actin-rich cortex. Analysis of VASP mutants and treatment of cells with anti-actin drugs shows that myosin recruitment and activation in Dictyostelium requires localized VASP-dependent actin polymerization. Targeting of DdMyo7 to the cortex alone is not sufficient for filopodia initiation; VASP activity is also required. The actin regulator locally produces a cortical actin network, that activates the MF myosin and together they shape the actin network to promote extension of parallel bundles during filopodia formation. This work reveals how filopodia initiation requires close collaboration between an actin binding protein, the state of the actin cytoskeleton and MF myosin activity.

scholarly journals VASP mediated actin dynamics activate and recruit a filopodia myosin

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Ashley L Arthur ◽  
Amy Crawford ◽  
Anne Houdusse ◽  
Margaret A Titus
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
The State ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Actin Network ◽  
Cortical Actin ◽  
Close Collaboration ◽  
Actin Binding Protein ◽  
Dynamic Regions

Filopodia are thin, actin-based structures that cells use to interact with their environments. Filopodia initiation requires a suite of conserved proteins but the mechanism remains poorly understood. The actin polymerase VASP and a MyTH-FERM (MF) myosin, DdMyo7 in amoeba, are essential for filopodia initiation. DdMyo7 is localized to dynamic regions of the actin-rich cortex. Analysis of VASP mutants and treatment of cells with anti-actin drugs shows that myosin recruitment and activation in Dictyostelium requires localized VASP-dependent actin polymerization. Targeting of DdMyo7 to the cortex alone is not sufficient for filopodia initiation; VASP activity is also required. The actin regulator locally produces a cortical actin network that activates myosin and together they shape the actin network to promote extension of parallel bundles of actin during filopodia formation. This work reveals how filopodia initiation requires close collaboration between an actin binding protein, the state of the actin cytoskeleton and MF myosin activity.

scholarly journals The c-Abl tyrosine kinase regulates actin remodeling at the immune synapse

Blood ◽  
2008 ◽  
Vol 112 (1) ◽  
pp. 111-119 ◽  
Author(s):  
Yanping Huang ◽  
Erin O. Comiskey ◽  
Renell S. Dupree ◽  
Shuixing Li ◽  
Anthony J. Koleske ◽  
...  
Keyword(s):  
T Cell ◽  
Tyrosine Kinase ◽  
T Cell Activation ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Kinase Inhibitors ◽  
Interleukin 2 ◽  
Conditional Knockout ◽  
Actin Dynamics ◽  
Immune Synapse

Abstract Actin dynamics during T-cell activation are controlled by the coordinate action of multiple actin regulatory proteins, functioning downstream of a complex network of kinases and other signaling molecules. The c-Abl nonreceptor tyrosine kinase regulates actin responses in nonhematopoietic cells, but its function in T cells is poorly understood. Using kinase inhibitors, RNAi, and conditional knockout mice, we investigated the role of c-Abl in controlling the T-cell actin response. We find that c-Abl is required for normal actin polymerization and lamellipodial spreading at the immune synapse, and for downstream events leading to efficient interleukin-2 production. c-Abl also plays a key role in signaling chemokine-induced T-cell migration. c-Abl is required for the appropriate function of 2 proteins known to be important for controlling actin responses to T-cell receptor (TCR) engagement, the actin-stabilizing adapter protein HS1, and the Rac1-dependent actin polymerizing protein WAVE2. c-Abl binds to phospho-HS1 via its SH2 domains and is required for full tyrosine phosphorylation of HS1 during T-cell activation. In addition, c-Abl is required for normal localization of WAVE2 to the immune synapse (IS). These studies identify c-Abl as a key player in the signaling cascade, leading to actin reorganization during T-cell activation.

Sign in / Sign up

Export Citation Format

Share Document