Cardiac hypertrophy triggered by mechanical load possesses features in common with growth factor signal transduction. A hemodynamic load provokes rapid expression of the growth factor-inducible nuclear oncogene, c-fos, and certain peptide growth factors specifically stimulate the "fetal" cardiac genes associated with hypertrophy, even in the absence of load. These include the gene encoding vascular smooth muscle alpha-actin, the earliest alpha-actin expressed during cardiac myogenesis; however, it is not known whether reactivation of the smooth muscle alpha-actin gene occurs in ventricular hypertrophy. We therefore investigated myocardial expression of the smooth muscle alpha-actin gene after hemodynamic overload. Smooth muscle alpha-actin mRNA was discernible 24 h after coarctation and was persistently expressed for up to 30 d. In hypertrophied hearts, the prevalence of smooth muscle alpha-actin gene induction was 0.909, versus 0.545 for skeletal muscle alpha-actin (P less than 0.05). ...
Actin, alpha skeletal muscle is a protein that in humans is encoded by the ACTA1 gene. Actin alpha 1 which is expressed in skeletal muscle is one of six different actin isoforms which have been identified. Actins are highly conserved proteins that are involved in cell motility, structure and integrity. Alpha actins are a major constituent of the contractile apparatus. Skeletal alpha actin expression is induced by stimuli and conditions known to cause muscle formation. Such conditions result in fusion of committed cells (satellite cells) into myotubes, to form muscle fibers. Skeletal actin itself, when expressed, causes expression of several other "myogenic genes", which are essential to muscle formation. One key transcription factor that activates skeletal actin gene expression is Serum Response Factor ("SRF"), a protein that binds to specific sites on the promoter DNA of the actin gene. SRF may bring a number of other proteins to the promoter of skeletal actin, such as andogen receptor, and ...
ACTC1 encodes cardiac muscle alpha actin. This isoform differs from the alpha actin that is expressed in skeletal muscle, ACTA1. Alpha cardiac actin is the major protein of the thin filament in cardiac sarcomeres, which are responsible for muscle contraction and generation of force to support the pump function of the heart. Cardiac alpha actin is a 42.0 kDa protein composed of 377 amino acids. Cardiac alpha actin is a filamentous protein extending from a complex mesh with cardiac alpha-actinin (ACTN2) at Z-lines towards the center of the sarcomere. Polymerization of globular actin (G-actin) leads to a structural filament (F-actin) in the form of a two-stranded helix. Each actin can bind to four others. The atomic structure of monomeric actin was solved by Kabsch et al., and closely thereafter this same group published the structure of the actin filament. Actins are highly conserved proteins; the alpha actins are found in muscle tissues and are a major constituent of the contractile apparatus. ...
TY - JOUR. T1 - Actin Filament Bundling and Different Nucleating Effects of Mouse Diaphanous-Related Formin FH2 Domains on Actin/ADF and Actin/Cofilin Complexes. AU - Machaidze, Gia. AU - Sokoll, Andrea. AU - Shimada, Atsushi. AU - Lustig, Ariel. AU - Mazur, Antonina. AU - Wittinghofer, Alfred. AU - Aebi, Ueli. AU - Mannherz, Hans Georg. PY - 2010/11/5. Y1 - 2010/11/5. N2 - Mouse Diaphanous-related formins (mDias) are members of the formin protein family that nucleate actin polymerization and subsequently promote filamentous actin (F-actin) elongation by monomer addition to fast-growing barbed ends. It has been suggested that mDias preferentially recruit actin complexed to profilin due to their proline-rich FH1 domains. During filament elongation, dimeric mDias remain attached to the barbed ends by their FH2 domains, which form an anti-parallel ring-like structure enclosing the filament barbed ends. Dimer formation of mDia-FH2 domains is dependent on their N-terminal lasso and linker subdomains ...
TY - JOUR. T1 - WASH phosphorylation balances endosomal versus cortical actin network integrities during epithelial morphogenesis. AU - Tsarouhas, Vasilios. AU - Liu, Dan. AU - Tsikala, Georgia. AU - Fedoseienko, Alina. AU - Zinn, Kai. AU - Matsuda, Ryo. AU - Billadeau, Daniel D.. AU - Samakovlis, Christos. PY - 2019/12/1. Y1 - 2019/12/1. N2 - Filamentous actin (F-actin) networks facilitate key processes like cell shape control, division, polarization and motility. The dynamic coordination of F-actin networks and its impact on cellular activities are poorly understood. We report an antagonistic relationship between endosomal F-actin assembly and cortical actin bundle integrity during Drosophila airway maturation. Double mutants lacking receptor tyrosine phosphatases (PTP) Ptp10D and Ptp4E, clear luminal proteins and disassemble apical actin bundles prematurely. These defects are counterbalanced by reduction of endosomal trafficking and by mutations affecting the tyrosine kinase Btk29A, and the ...
The current evidence suggests that c-Abl and Arg kinases are activated and recruited by different extracellular stimuli to regulate distinct F-actin structures. Progress has been made in understanding the mechanisms of c-Abl activation by growth factors and the ECM, and in identifying some of the substrates or collaborators of c-Abl in regulating the F-actin cytoskeleton. Because c-Abl is involved in several different F-actin-dependent processes, it is likely to collaborate with other F-actin regulators to determine the dynamic biological output. Multi-protein complexes containing c-Abl or c-Abl substrates may have specific subcellular localization to regulate distinct F-actin structures in various F-actin-dependent processes. Further investigation is now required to characterize the key upstream components in c-Abl cytoskeletal signaling pathways. Moreover, it is important to determine precisely when, where and why the crucial c-Abl substrates are phosphorylated and how this affects the ...
Branched actin networks harness the free energy of actin filament assembly to generate forces required for many important cellular processes (Pollard & Cooper, 2009; Blanchoin et al, 2014). These self‐assembling, cytoskeletal structures push against loads (generally cellular membranes) by promoting nucleation and elongation of actin filaments near the load surface (Pollard et al, 2000). Filament nucleation in branched networks is controlled by membrane‐associated signaling molecules, which recruit nucleation‐promoting factors (NPFs) that, in turn, localize the Arp2/3 complex and stimulate its actin nucleation activity (Pollard et al, 2000; Rotty et al, 2013). Filament elongation near the membrane surface is generally assumed to occur via diffusion‐limited incorporation of actin monomers directly from solution (Pollard et al, 2000), with possible assistance from membrane‐associated actin polymerases, such as formins and Ena/VASP proteins (Dominguez, 2009). The fact that neither formins ...
Work in T cells has demonstrated that actin cytoskeleton rearrangement and lipid raft polarization induced by contact with an APC are dependent on Vav1 activity (10-12). Therefore, early signals upstream of actin polymerization that induce Vav1 phosphorylation must exist. Activation receptor 2B4 on NK cells is not likely to provide such early signals because 2B4 phosphorylation is itself dependent on actin polymerization (20). To test if LFA-1 engagement on NK cells can activate Vav1 upstream of cytoskeleton rearrangements, actin polymerization was blocked by treatment with cytochalasin D and Latrunculin A. As shown in Fig. 3 B, these inhibitors did not block the Vav1 phosphorylation induced by SC2-ICAM cells. In contrast, and consistent with the actin polymerization-dependent phosphorylation of 2B4 (20), the enhancement of Vav1 phosphorylation due to coengagement of 2B4 with LFA-1 was blocked by cytochalasin D and Latrunculin A (Fig. 3 B). These results show that these inhibitors were effective ...
Tropomyosin (Tpm) isoforms are the master regulators of the functions of individual actin filaments in fungi and metazoans. Tpms are coiled-coil parallel dimers that form a head-to-tail polymer along the length of actin filaments. Yeast only has two Tpm isoforms, whereas mammals have over 40. Each cytoskeletal actin filament contains a homopolymer of Tpm homodimers, resulting in a filament of uniform Tpm composition along its length. Evidence for this master regulator role is based on four core sets of observation. First, spatially and functionally distinct actin filaments contain different Tpm isoforms, and recent data suggest that members of the formin family of actin filament nucleators can specify which Tpm isoform is added to the growing actin filament. Second, Tpms regulate whole-organism physiology in terms of morphogenesis, cell proliferation, vesicle trafficking, biomechanics, glucose metabolism and organ size in an isoform-specific manner. Third, Tpms achieve these functional outputs ...
Tropomyosin (Tpm) isoforms are the master regulators of the functions of individual actin filaments in fungi and metazoans. Tpms are coiled-coil parallel dimers that form a head-to-tail polymer along the length of actin filaments. Yeast only has two Tpm isoforms, whereas mammals have over 40. Each cytoskeletal actin filament contains a homopolymer of Tpm homodimers, resulting in a filament of uniform Tpm composition along its length. Evidence for this master regulator role is based on four core sets of observation. First, spatially and functionally distinct actin filaments contain different Tpm isoforms, and recent data suggest that members of the formin family of actin filament nucleators can specify which Tpm isoform is added to the growing actin filament. Second, Tpms regulate whole-organism physiology in terms of morphogenesis, cell proliferation, vesicle trafficking, biomechanics, glucose metabolism and organ size in an isoform-specific manner. Third, Tpms achieve these functional outputs ...
We have shown previously (Schwartz, M. A., and E. J. Luna. 1986. J. Cell Biol. 102: 2067-2075) that actin binds with positive cooperativity to plasma membranes from Dictyostelium discoideum. Actin is polymerized at the membrane surface even at concentrations well below the critical concentration for polymerization in solution. Low salt buffer that blocks actin polymerization in solution also prevents actin binding to membranes. To further explore the relationship between actin polymerization and binding to membranes, we prepared four chemically modified actins that appear to be incapable of polymerizing in solution. Three of these derivatives also lost their ability to bind to membranes. The fourth derivative (EF actin), in which histidine-40 is labeled with ethoxyformic anhydride, binds to membranes with reduced affinity. Binding curves exhibit positive cooperativity, and cross-linking experiments show that membrane-bound actin is multimeric. Thus, binding and polymerization are tightly ...
Disassembly of the epithelial apical junctional complex (AJC), composed of the tight junction (TJ) and adherens junction (AJ), is important for normal tissue remodeling and pathogen-induced disruption of epithelial barriers. Using a calcium depletion model in T84 epithelial cells, we previously found that disassembly of the AJC results in endocytosis of AJ/TJ proteins. In the present study, we investigated the role of the actin cytoskeleton in disassembly and internalization of the AJC. Calcium depletion induced reorganization of apical F-actin into contractile rings. Internalized AJ/TJ proteins colocalized with these rings. Both depolymerization and stabilization of F-actin inhibited ring formation and disassembly of the AJC, suggesting a role for actin filament turnover. Actin reorganization was accompanied by activation (dephosphorylation) of cofilin-1 and its translocation to the F-actin rings. In addition, Arp3 and cortactin colocalized with these rings. F-actin reorganization and disassembly of
Author Summary Actin is one of the best studied, evolutionary conserved and most abundant intracellular proteins. Actin can exists in globular and filamentous functionally distinct forms, and is involved in a variety of biological processes, such as muscle contraction, cell motility, cell division, vesicle and organelle movement, endocytosis, and cell signaling. Here we show a novel function of insect cytoplasmic actin, as an extracellular immune factor. Actin is externalized by insect immune competent cells upon immune challenge with bacteria or bacterial surface components, and once externalized, actin binds with high affinity to the surface of bacteria. A functional role of actins interaction with bacteria is to mediate their killing through either phagocytosis or direct antibacterial action. The globular and filamentous forms of actins appear to play distinct functions as extracellular immune factors. Actin also plays a role as a Plasmodium antagonist as it limits parasite infection of the mosquito
Fission yeast cells use Arp2/3 complex and formin to assemble diverse filamentous actin (F-actin) networks within a common cytoplasm for endocytosis, division, and polarization. Although these homeostatic F-actin networks are usually investigated separately, competition for a limited pool of actin monomers (G-actin) helps to regulate their size and density. However, the mechanism by which G-actin is correctly distributed between rival F-actin networks is not clear. Using a combination of cell biological approaches and in vitro reconstitution of competition between actin assembly factors, we found that the small G-actin binding protein profilin directly inhibits Arp2/3 complex-mediated actin assembly. Profilin is therefore required for formin to compete effectively with excess Arp2/3 complex for limited G-actin and to assemble F-actin for contractile ring formation in dividing cells.
Cell behavior is controlled by extracellular signals that work through signal transduction pathways to regulate the organization of the actin cytoskeleton. Some of these extrinsic signals positively affect the cytoskeleton and induce actin polymerization, but extrinsic signals that negatively regulate and disassemble actin filaments also exist. A family of multidomain proteins, the MICALs, directly associates with Semaphorins, cell surface receptors involved in negative or repulsive cues. Working with purified proteins and in vivo, Hung et al. now find that actin filaments serve as a direct substrate for Micals enzymatic activity. Mical posttranslationally alters actin at its methionine 44 residue, which disrupts the association between actin monomers and cutting actin filaments. Altering the methionine 44 residue makes actin resistant to Mical-mediated disassembly in vitro and in vivo in Drosophila.. R.-J. Hung, C. W. Pak, J. R. Terman, Direct redox regulation of F-actin assembly and ...
Actin and myosin are the two major cytoskeletal proteins implicated in cell motility. As constituents of many cell types, actin and myosin are involved in a myriad of cellular process including locomotion, secretion, cytoplasmic streaming, phagocytosis, and cytokinesis. Actin is one of the most conserved eukaryotic proteins with at least six isoforms. Four of the isoforms represent the differentiation markers of muscle tissues and two are found in almost all cells. There are three α-actins (skeletal, cardiac, and smooth muscle), one β-actin (β-nonmuscle), and two γ-actins (γ-smooth muscle and γ-nonmuscle). Actin isoforms show greater than 90% overall sequence homology, but only 50-60% homology in their 18 NH2-terminal residues. The NH2-terminal region of actin appears to be a major antigenic region and may be involved in the interaction of actin with other proteins such as myosin.. Note: Historically, due to its ubiquitous nature, β-Actin was used as an internal standard for Western ...
Actin plays a major role in the structural integrity and motility of cells as well as in the intracellular dynamics of other macromolecules. Photon Correlation Spectroscopy (PCS) has been used to monitor the diffusion of polystyrene latex spheres (PLS) of different sizes within in vitro polymerized actin solutions under a variety of conditions. Specific actin-binding proteins were added to regulate the actin filament lengths as well as to cross-link filaments together. PCS measurements give information on the mobility of PLS over probing distances equal to the inverse scattering vector magnitude which range from 40 to 420 nm for the data. Results allow estimation of the mean pore sizes within the actin networks as a function of both actin concentration (0.4 - 5 mg/ml) and the presence of actin-binding proteins. Probe diffusion coefficients were measured for PLS samples in length-regulated actin networks at a fixed actin concentration, c (0.65 mg/ml) as c*, the semi-dilute overlap concentration, ...
The connection between T cell activation, plasma membrane order and actin filament dynamics was the main focus of this study. Laurdan and di-4-ANEPPDHQ, membrane order sensing probes, were shown to report only on lipid packing rather than being influenced by the presence of membrane-inserted peptides justifying their use in membrane order studies. These dyes were used to follow plasma membrane order in live cells at 37°C. Disrupting actin filaments had a disordering effect while stabilizing actin filaments had an ordering effect on the plasma membrane, indicating there is a basal level of ordered domains in resting cells. Lowering PI(4,5)P2 levels decreased the proportion of ordered domains strongly suggesting that the connection of actin filaments to the plasma membrane is responsible for the maintaining the level of ordered membrane domains. Membrane blebs, which are detached from the underlying actin filaments, contained a low fraction of ordered domains. Aggregation of membrane components ...
Actin protein derived from rabbit skeletal muscle supplied at |99% purity. Extensive list of citations and additional actin protein research tools available.
To test whether the BODIPY-PtdIns(3,4,5)P3‐induced polarizing pseudopod was based on the actin cytoskeleton, cytochalasin B, an actin polymerization inhibitor, was used. When pre‐treated with cytochalasin B (5 μg ml−1) before loading with BODIPY-PtdIns(3,4,5)P3, no polarizing pseudopodia formed. After cell morphological polarization was initiated, but before full retraction of PtdIns(3,4,5)P3 into the uropod (Fig. 3C), cytochalasin B caused withdrawal of the polarizing pseudopod (Fig. 3A) without an accompanying release of BODIPY-PtdIns(3,4,5)P3, which remained immobilized and polarized (Fig. 3Af). Thus, the formation of the polarizing pseudopod was dependent on actin polymerization, but the tethering PtdIns(3,4,5)P3 was not sensitive to cytochalasin B. This latter evidence might not rule out the cytoskeleton as the immobilization tether because, unlike F‐actin in pseudopodia, the cortical actin network is largely resistant to depolymerization by cytochalasins (Sheterline et al., 1986, ...
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Actin cytoskeleton remodeling requires the coordinated action of a large number of actin binding proteins that reorganize the actin cytoskeleton by promoting polymerization, stabilizing filaments, causing branching, or crosslinking filaments. Palladin is a key cytoskeletal actin binding protein whose normal function is to enable cell motility during development of tissues and organs of the embryo and in wound healing, but palladin is also responsible for regulating the ability of cancer cells to become invasive and metastatic. The membrane phosphoinositide phosphatidylinositol (PI) 4,5-bisphosphate [PI(4,5)P-2] is a well-known precursor for intracellular signaling and a bona fide regulator of actin cytoskeleton reorganization. Our results show that two palladin domains [immunoglobulin (Ig) 3 and 34] interact with the head group of PI(4,5)P-2 with moderate affinity (apparent K-d = 17 mu M). Interactions with PI(4,5)P-2 decrease the actin polymerizing activity of Ig domain 3 of palladin ...
Cell motility plays an important role in many basic biological processes, including embryogenesis, neurite growth, wound healing, inflammation, and cancer metastasis. Motility of crawling cells is dependent on the ability to extend F-actin-rich protrusions, usually in the form of lamellipods (Abercrombie et al. 1970; Chen et al. 1994; Verschueren et al. 1994; Xie et al. 1995). Protrusion of such actin-rich lamellipods in moving cells requires cycles of actin polymerization and depolymerization (actin polymerization transients) (Lauffenburger and Horwitz 1996; Mitchison and Cramer 1996; Bailly et al. 1998a; Condeelis 1998).. Previous studies have demonstrated the requirement for free barbed ends in the control of this cycle (Handel et al. 1990; Symons and Mitchison 1991; Chan et al. 1998). We have shown previously that stimulation of metastatic MTLn3 cells with EGF causes a transient increase in actin nucleation activity resulting from the appearance of free barbed ends at the extreme leading ...
We discuss here some aspects of local and global self-organization of the actomyosin cytoskeleton in the fibroblast-type cells. (1) Locally, the cytoplasm comprises a multi-nodal network formed by small asters of actin filaments nucleated by DAAM1 formin and stabilized by the actin crosslinking protein filamin A. The asters are connected with each other by myosin II, so that the entire system forms a contractile network responsible for the maintenance of the cell shape. (2) Observations of the assembly of myosin-II filament arrays by structured illumination microscopy (SIM) revealed myosin-II "stacks" formed by alignment in register of the myosin-II bipolar filaments associated with actin fibers. In the cells spread over the planar substrate, the numerous myosin stacks apparently form the links between neighboring actin filament bundles (stress-fibers or arcs), maintaining the organization of the actin cytoskeleton. (3) Globally, upon spreading on planar substrate s, cells develop chiral arrays ...
Alpha Cardiac Actin antibody LS-C153366 is an unconjugated rabbit polyclonal antibody to Alpha Cardiac Actin (ACTC1) from human. It is reactive with human, mouse and rat. Validated for ELISA, IHC and WB.
Polyclonal antibody for GAMMA ACTIN/ACTG1 detection. Host: Rabbit.Size: 100μg/vial. Tested applications: IHC-P. Reactive species: Human. GAMMA ACTIN/ACTG1 information: Molecular Weight: 41793 MW; Subcellular Localization: Cytoplasm, cytoskeleton.
Rabbit polyclonal alpha smooth muscle Actin antibody. Validated in WB, ELISA, IHC, ICC/IF and tested in Mouse, Rat, Chicken, Guinea pig, Cow, Dog, Human, Pig. Cited in 1376 publication(s)…
The polymerization of scallop p-like actin is significantly slower than that of skeletal muscle alpha-actin. To reveal which steps of polymerization contribute to this difference, we estimated the efficiency of nucleation of the two actins, the rates of filament elongation at spontaneous and gelsolin-nucleated polymerization and the turnover rates of the filament Subunits at steady-state. Scallop actin nucleated nearly twice less efficient than rabbit actin. In actin filaments with free ends, when dynamics at the barbed ends overrides that at the pointed ends, the relative association rate constants of alpha- and beta-actin were similar, whereas the relative dissociation rate constant of beta-ATP-actin subunits was 2- to 3-fold higher than that of alpha-actin. The 2- to 3-fold faster polymerization of skeletal muscle versus scallop Ca-actin was preserved with gelsolin-capped actin filaments when only polymerization at the pointed end is possible. With gelsolin-induced polymerization, the rate ...
Constitutive centripetal transport of the actin-based cytoskeleton has been detected in cells spreading on a substrate, locomoting fibroblasts and keratocytes, and non-locomoting serum-deprived fibroblasts. These results suggest a gradient of actin assembly, highest in the cortex at the cytoplasm-membrane interface and lowest in the non-cortical perinuclear cytoplasm. We predicted that such a gradient would be maintained in part by phosphoinositide-regulated actin binding proteins because the intracellular free Ca2+ and pH are low and spatially constant in serum-deprived cells. The cytoplasm-membrane interface presents one surface where the assembly of actin is differentially regulated relative to the non-cortical cytoplasm. Several models, based on in vitro biochemistry, propose that phosphoinositide-regulated actin binding proteins are involved in local actin assembly. To test these models in living cells using imaging techniques, we prepared a new fluorescent analog of actin that bound ...
Rabbit polyclonal Actin antibody validated for WB, IHC and tested in Human and Rat. Referenced in 2 publications and 1 independent review. Immunogen…
Actin is a major component of the cytoskeleton and is present as two isoforms in non-muscle cells: β- and γ-cytoplasmic actin. These isoforms are strikingly conserved, differing by only four N-terminal amino acids. During spread from infected cells, vaccinia virus (VACV) particles induce localized actin nucleation that propel virus to surrounding cells and facilitate cell-to-cell spread of infection. Here we show that virus-tipped actin comets are composed of β- and γ-actin. We employed isoform-specific siRNA knockdown to examine the role of the two isoforms in VACV-induced actin comets. Despite the high level of similarity between the actin isoforms, and their colocalization, VACV-induced actin nucleation was dependent exclusively on β-actin. Knockdown of β-actin led to a reduction in the release of virus from infected cells, a phenotype dependent on virus-induced Arp2/3 complex activity. We suggest that local concentrations of actin isoforms may regulate the activity of cellular actin ...
Rabbit Polyclonal Anti-alpha-Smooth Muscle Actin Antibody. Mesenchymal Cell Marker. Validated: WB, IP. Tested Reactivity: Human. 100% Guaranteed.
Image analysis was performed in MATLAB. To quantify actin structure, we defined the actin distribution parameter (ADP) as the standard deviation of pixel intensity within a region of interest (ROI). A higher ADP indicates the presence of high contrast features including stress fibers. The ROI was defined as the inner 50% of the cellular area. Cell area was calculated based on cell shape, determined by a manual trace of the cortical actin band in the apical region. Quantification was performed on all cells in all 5 locations averaged per specimen (avg N = 193 cells/specimen). One-way ANOVA was used for statistical analysis.. Results : At 0 , t , 12 hrs, ECs exhibited a cortical double-banded actin structure as well as stress fibers spanning the entire cell (Fig. 1, Fig. 2A). At increasing DPT, the double band disappeared and actin distribution became increasingly homogeneous and diffuse throughout the cytoplasm. As a result, ADP significantly decreased (p=0.007 for 0 , t , 12 hrs vs. 24 , t , 48 ...
beta Actin antibody Mouse Monoclonal from Proteintech validated in Western Blot (WB), Immunoprecipitation (IP), Immunohistochemistry (IHC), Immunofluorescence (IF), Flow Cytometry (FC), Enzyme-linked Immunosorbent Assay (ELISA) applications. This antibody reacts with human, mouse, rat, hamster, zebrafish,monkey samples. Cat.No. 66009-1-Ig. KD/KO Validated.
GenScript THETM beta Actin Antibody [HRP], mAb, Mouse is HRP conjugated THETM beta Actin Antibody, mAb, Mouse (A00702) purified from mice ascites by protein G affinity column. This product provides a useful and serves as a specific tool in the study of the intracellular distribution of ß-actin a...
Skeletal muscle actin binding protein spin-down assay kit provides G- or F-actin plus positive (α-actinin ) and negative (Bovine Serum Albumin, BSA) binding control proteins. Kit contains skeletal muscle actin.
Treatment with SMIFH2 decreases the actin level in oocytes and impairs spindle formation.A. Treatment with SMIFH2 decreases the cortical actin level in maturing
Proteins bind to filamentous actin (F-actin) through distinct actin binding modules. In this video we demonstrate the procedure of...
Mouse Monoclonal Anti-pan Actin Antibody (HHF35) [DyLight 405]. Muscle Cell Marker. Validated: WB, Flow, ICC/IF, IHC-Fr, IHC-P. Tested Reactivity: Human, Mouse, Rat, and more. 100% Guaranteed.
Monoclonal Antibody for studying ACTA1 (alpha actin, skeletal muscle)/ACTA2 (alpha actin, smooth muscle)/ACTC1 (alpha cardiac actin)/ACTG1 (gamma actin cytoplasmic nonmuscle)/ACTG2 (gamma actin, cytoplasmic)/beta-Actin in the Cytoskeletal Signaling research area.
Leukocytes arrested on inflamed endothelium via integrins are subjected to force imparted by flowing blood. How leukocytes respond to this force and resist detachment is poorly understood. Live-cell imaging with Lifeact-transfected U937 cells revealed that force triggers actin polymerization at upstream α4β1 integrin adhesion sites and the adjacent cortical cytoskeleton. Scanning electron microscopy revealed that this culminates in the formation of structures that anchor monocyte adhesion. Inhibition of actin polymerization resulted in cell deformation, displacement, and detachment. Transfection of dominant-negative constructs and inhibition of function or expression revealed key signaling steps required for upstream actin polymerization and adhesion stabilization. These included activation of Rap1, phosphoinositide 3-kinase γ isoform, and Rac but not Cdc42. Thus, rapid signaling and structural adaptations enable leukocytes to stabilize adhesion and resist detachment forces. ...
For directional movement, eukaryotic cells depend on the proper organization of their actin cytoskeleton. This engine of motility is made up of highly dynamic nonequilibrium actin structures such as flashes, oscillations, and traveling waves. In Dictyostelium, oscillatory actin foci interact with signals such as Ras and phosphatidylinositol 3,4,5-trisphosphate (PIP3) to form protrusions. However, how signaling cues tame actin dynamics to produce a pseudopod and guide cellular motility is a critical open question in eukaryotic chemotaxis. Here, we demonstrate that the strength of coupling between individual actin oscillators controls cell polarization and directional movement. We implement an inducible sequestration system to inactivate the heterotrimeric G protein subunit Gβ and find that this acute perturbation triggers persistent, high-amplitude cortical oscillations of F-actin. Actin oscillators that are normally weakly coupled to one another in wild-type cells become strongly synchronized following
Drosophila S2 cells offer a powerful tool to study in vivo dynamics and organization of the actin cytoskeleton. When plated on the lectin, concanavalin A, S2 cells attach and spread on the substrate to form a circumferential actin-based lamellae. The susceptibility of these cells to gene inhibition using RNAi makes them a very tractable system to dissect the molecular machinery involved in lamellipod formation. The figure shows a control S2 (upper left) in comparison with cells depleted of capping protein beta (upper right), cofilin (lower left), and Rho1 (lower right). The hyper-ruffled morphology produced by capping protein RNAi is consistent with its role in terminating actin filament elongation - in the absence of the protein, actin filaments polymerization pushes on the membrane in an unregulated manner. Depletion of cofilin, a factor required for actin filament turnover, produces cells that are unable to spread due to abnormal accumulations of f-actin at their cortex. RNAi-inhibition of ...
The thinnest fibers of the cytoskeleton (measuring approximately 6 nm in diameter),[2] microfilaments are formed by the head-to-tail polymerization of actin monomers (also known as globular or G-actin). Actin subunits as part of a fiber are referred to as filamentous actin (or F-actin). Each microfilament is made up of two helical interlaced strands of subunits. Much like microtubules, actin filaments are polarized, with their fast-growing barbed-ends (because of their appearance in electron micrographs after binding of myosin S1 sub-fragments) and a slow-growing pointed-end (again based on the pattern created by S1 binding). The pointed end is sometimes referred to as the minus (-) end and the barbed end is sometimes referred to as the plus (+) end because of the growth rates, but this is nomenclature adapted from the microtubule field, and is not generally accepted in the actin field.. In vitro actin polymerization, nucleation, starts with the self-association of three G-actin monomers to form ...
Activation of the membrane estrogen receptor G-protein-coupled estrogen receptor (GPER) in ovariectomized mice via the GPER agonist G-1 mimics the beneficial effects of 17β-estradiol (E2) on hippocampal CA1 spine density and memory consolidation, yet the cell-signaling mechanisms mediating these effects remain unclear. The present study examined the role of actin polymerization and c-Jun N-terminal kinase (JNK) phosphorylation in mediating effects of dorsal hippocampally infused G-1 on CA1 dendritic spine density and consolidation of object recognition and spatial memories in ovariectomized mice. We first showed that object learning increased apical CA1 spine density in the dorsal hippocampus (DH) within 40 min. We then found that DH infusion of G-1 increased both CA1 spine density and phosphorylation of the actin polymerization regulator cofilin, suggesting that activation of GPER may increase spine morphogenesis through actin polymerization. As with memory consolidation in our previous work ...
Cell migration is central to embryonic development, homeostasis and disease, processes in which cells move as part of a group or individually. Whereas the mechanisms controlling single-cell migration in vitro are relatively well understood, less is known about the mechanisms promoting the motility of individual cells in vivo. In particular, it is not clear how cells that form blebs in their migration use those protrusions to bring about movement in the context of the three-dimensional cellular environment. Here we show that the motility of chemokine-guided germ cells within the zebrafish embryo requires the function of the small Rho GTPases Rac1 and RhoA, as well as E-cadherin-mediated cell-cell adhesion. Using fluorescence resonance energy transfer we demonstrate that Rac1 and RhoA are activated in the cell front. At this location, Rac1 is responsible for the formation of actin-rich structures, and RhoA promotes retrograde actin flow. We propose that these actin-rich structures undergoing ...
To understand the cytoskeleton, it helps to also gain some background in simple polymer assembly, and the mathematics used to describe it. Here I review a succession of elementary models for polymers of various types starting from a mixture consisting only of subunits, called monomers. I point out that the accumulated polymer mass over time depends on the type of underlying assembly reaction. The idea of critical monomer concentration is introduced, and shown to arise as a consequence of scaling the models. We then consider the specific case of actin polymers and show that treadmilling (growth of one end and shrinkage of the other) can occur at a particular concentration. Growth of actin filaments at their tips in discussed in the context of a transcritical bifurcation. I introduce the Mogilner-Oster thermal ratchet and its relation to cell protrusion caused by actin filament polymerization against a load force. ...
Heavy meromyosin (HMM) decoration of actin filaments was used to detect the polarity of microfilaments in interphase and cleaving rat kangaroo (PtK2) cells. Ethanol at -20 degrees C was used to make the cells permeable to HMM followed by tannic acid-glutaraldehyde fixation for electron microscopy. Uniform polarity of actin filaments was observed at cell junctions and central attachment plaques with the HMM arrowheads always pointing away from the junction or plaque. Stress fibers were banded in appearance with their component microfilaments exhibiting both parallel and antiparallel orientation with respect to one another. Identical banding of microfilament bundles was also seen in cleavage furrows with the same variation in filament polarity as found in stress fibers. Similarly banded fibers were not seen outside the cleavage furrow in mitotic cells. By the time that a mid-body was present, the actin filaments in the cleavage furrow were no longer in banded fibers. The alternating dark and light ...
Alpha-Smooth Muscle Actin, eFluor 660, clone: 1A4, eBioscience™ 25μg; eFluor 660 Alpha-Smooth Muscle Actin, eFluor 660, clone: 1A4, eBioscience™ Primary...