Pure actin used in research and drug discovery, active actin, actin assay, pyrene actin, fluorescent actin, rhodamine actin, hilyte actin, alexa fluor actin, biotin actin, actin, Actin Protein, Arp2/3 protein, Arp2, Arp3, arp2/3 complex, arp2/3 assay, cofilin, profilin, fodrin, spectrin, tropomyosin, tropomodulin, myosin, actin buffer, actin polymerization buffer, actin cytoskeleton, actin binding proteins, filamin, alpha-actinin, gelsolin.
The heart is a dynamic organ that is made up of multiple cell types including muscle and non-muscle. In general the heart is capable of changing due to many factors including development, physiological response, and pathological conditions. Fibrotic (scarring) and hypertrophic (increase in cell size) diseases of the heart are often associated with messengers (such as calcium (Ca2+)) and pathways that activate proteins normally expressed only in the developing heart. One of these proteins, vascular smooth muscle alpha actin (SMA), is the predominant actin in smooth muscle, but is not normally expressed in the adult heart. However, SMA is activated in response to heart transplant and the associated rejection process (fetal reactivation). The focus of this project is to determine the role of Ca2+ in the regulation of SMA in resident non-muscle cell types of the heart. By using cultured cells we have determined that Ca2+ levels and/or Ca2+ agonists effect previously identified transcription factors ...
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 ...
More than 200 mutations in the skeletal muscle α-actin gene (ACTA1) cause either dominant or recessive skeletal muscle disease. Currently, there are no specific therapies. Cardiac α-actin is 99% identical to skeletal muscle α-actin and the predominant actin isoform in fetal muscle. We previously showed cardiac α-actin can substitute for skeletal muscle α-actin, preventing the early postnatal death of Acta1 knock-out mice, which model recessive ACTA1 disease. Dominant ACTA1 disease is caused by the presence of poison mutant actin protein. Experimental and anecdotal evidence nevertheless indicates that the severity of dominant ACTA1 disease is modulated by the relative amount of mutant skeletal muscle α-actin protein present. Thus, we investigated whether transgenic over-expression of cardiac α-actin in postnatal skeletal muscle could ameliorate the phenotype of mouse models of severe dominant ACTA1 disease. In one model, lethality of ACTA1(D286G). Acta1(+/-) mice was reduced from ∼59% before
Muscle disease caused by mutations in the skeletal muscle alpha-actin gene (ACTA1). Neuromuscul Disord. 2003 Sep; 13(7-8):519-31 ...
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 ...
Actin filament dynamics govern many key physiological processes from cell motility to tissue morphogenesis. A central feature of actin dynamics is the capacity of the filament to polymerize and depolymerize at its ends in response to cellular conditions. It is currently thought that filament kinetics can be described by a single rate constant for each end. Here, using direct visualization of single actin filament elongation, we show that actin polymerization kinetics at both filament ends are strongly influenced by proteins that bind to the lateral filament surface. We also show that the less dynamic end, called the pointed-end, has a non-elongating state that dominates the observed filament kinetic asymmetry. Estimates of filament flexibility and Brownian dynamics simulations suggest that the observed kinetic diversity arises from structural alteration. Tuning filament kinetics by exploiting the natural malleability of the actin filament structure may be a ubiquitous mechanism to generate 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 ...
Interstitial cells in the scars of human myocardial infarctions of different postinfarction times (6 hours to 17 years old) were characterized by antibodies to alpha-smooth muscle actin (ASMA), vimentin, and desmin. Basal lamina deposition was studied with antibodies to the basal lamina protein type …
Anti-Actin Antibody, Alexa Fluor 488 Conjugate clone, from rabbit, ALEXA FLUOR® 488; Synonym: Actin, alpha skeletal muscle, Alpha-actin-1; find Sigma-Aldrich-ABT1485-AF488 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich.
Anti-Actin Antibody, clone C4 ascites fluid, clone C4, Chemicon®; Synonym: MAB1501X, MAB1501R; find Sigma-Aldrich-MAB1501 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich.
Most fungi and metazoan cells have the capacity to express multiple isoforms of Tpm, resulting from either different gene products or different post-translational modifications. The biophysical properties of each Tpm filament and the specific way in which they interact with actin can differ significantly. This cooperative interaction with the actin polymer is crucial for Tpm function because it regulates interactions with other actin-binding proteins (e.g. myosins and cofilin) (Bryce et al., 2003), as well as the biophysical and/or dynamic properties of the actin filament. Different Tpms are, therefore, able to impart distinct physical properties to different actin filaments and, thereby, dictate their function. As many cell types can express multiple Tpm isoforms, it is crucial for the viability, function and mobility of a cell to recruit the appropriate Tpm to an actin polymer at the correct place and time (Bach et al., 2009). Indeed, we know that different Tpms are sorted to different actin ...
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 ...
TY - JOUR. T1 - Formins. T2 - Processive cappers of growing actin filaments. AU - Watanabe, Naoki. AU - Higashida, Chiharu. PY - 2004/11/15. Y1 - 2004/11/15. N2 - Taking the advantage of single-molecule imaging, our recent study has revealed surprisingly long processive movement of a Formin protein, mDia1, surfing along with the growing end of actin filaments in living cells. This finding provides direct evidence for the ability of Formins to function as processive cappers that has been postulated from several lines of evidence in biochemical studies. With nucleating filaments from the profilin-actin pool, Formins may effectively generate long actin filaments, and contribute to the generation of the specific actin-based structures, that is, the contractile ring in cytokinesis, actin stress fibers in animal cells, and yeast actin cables. Furthermore, Formins have the potential to function as actin polymerization-driven molecular motors. Although much remains to be tested about the role of this ...
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 ...
TY - JOUR. T1 - Actin mRNA localizes in the absence of protein synthesis. AU - Sundell, C. L.. AU - Singer, R. H.. PY - 1990. Y1 - 1990. N2 - Actin mRNA is localized in chicken embryo fibroblasts to the distal regions of leading lamellae, but not within the ruffling edges. In this investigation we have addressed the role of actin translation in this process. The translocation of actin mRNA to the cell periphery was studied by monitoring the distribution of actin mRNA in cells during spreading. Within 90 min, actin mRNA moved from a perinuclear to a peripheral distribution. Formation of lamellipodia preceded actin mRNA localization, indicating that localization is not a prerequisite for this event. Neither puromycin (which dissociates ribosomes from mRNA) nor cycloheximide (which stabilizes ribosomes on mRNA) had any effect on this movement of actin mRNA. Anchoring of actin mRNA was studied using cells with peripherally localized actin mRNA. No change in actin mRNA localization was observed for ...
Intestinal epithelial barrier is critical for the maintenance of normal gut homeostasis and disruption of this barrier may trigger or exaggerate mucosal inflammation. The actin cytoskeleton is a key regulator of barrier structure and function, controlling the assembly and permeability of epithelial adherens and tight junctions. Epithelial cells express two actin isoforms: a β-cytoplasmic actin and γ-cytoplasmic actin. Our previous in vitro studies demonstrated that these actin isoforms play distinctive roles in establishing the intestinal epithelial barrier, by controlling the organization of different junctional complexes. It remains unknown, whether β-actin and γ-actin have unique or redundant functions in regulating the gut barrier in vivo. To address this question, we selectively knocked out β-actin expression in mouse intestinal epithelium. Mice with intestinal epithelial knockout of β-actin do not display gastrointestinal abnormalities or gross alterations of colonic mucosal architecture.
Cell migration involves a coordinated cycle of plasma membrane protrusion at the leading edge, adhesion site formation under the protrusion, disruption of older adhesion sites at the cell rear, and cytoskeleton contraction against adhesions to yield cell body movement (1). Protrusion is thought to result from actin filament (F-actin) polymerization against the plasma membrane (2), with the polymerization rate regulated by the rate of monomer addition to the fast-growing (barbed) ends of filaments. This may depend on actin-related protein 2/3 (Arp2/3) complex activation, which creates free barbed ends by branching and de novo nucleation of filaments (dendritic nucleation) (3), and on actin depolymerizing factor (ADF) cofilin, which creates free barbed ends by severing preexisting filaments and promoting depolymerization of free filament pointed ends (4). Filament growth is limited by barbed end-capping proteins and depletion of the polymerization-competent pool of actin monomers (5).. We ...
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
Quantitative and qualitative changes in cellular actin were followed during differentiation of a myeloid leukemia cell line, namely Ml, which was inducible with conditioned medium (CM). During 3 d of incubation with CM, when the Ml cells differentiated to macrophages and lost their mitotic activity, the actin content, F-actin ratio in total actin, and the actin synthesis showed an increase. A greater difference before and after differentiation was found in the ability of G-actin to polymerize. Actin harvested from CM-treated cells showed a greater ability to polymerize, depending on the increased concentration of MgCl2 and/or KCl and proteins, as compared with the actin from untreated Ml cells. Actin harvested from the Mml cell line, a macrophage line, had a particularly high polymerizability with or without CM treatment. In contrast, the actin from the D- subline, which is insensitive to CM, showed almost no polymerization. ...
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 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.
Drosophila Quail protein is required for the completion of fast cytoplasm transport from nurse cells to the oocyte, an event critical for the production of viable oocytes. The abundant network of cytoplasmic filamentous actin, established at the onset of fast transport, is absent in quail mutant egg chambers. Previously, we showed that Quail is a germline-specific protein with sequence homology to villin, a vertebrate actin-regulating protein. In this study, we combined biochemical experiments with observations in egg chambers to define more precisely the function of this protein in the regulation of actin-bundle assembly in nurse cells. We report that recombinant Quail can bind and bundle filamentous actin in vitro in a manner similar to villin at a physiological calcium concentration. In contrast to villin, Quail is unable to sever or cap filamentous actin, or to promote nucleation of new actin filaments at a high calcium concentration. Instead, Quail bundles the filaments regardless of the ...
To address the mechanism behind the altered cytoskeleton organization phenotypes of NAA80-KO cells, we analyzed the recovery rates of cytoskeletal structures in cells treated with the actin-depolymerizing drug latrunculin A (LatA). Within 60 min of LatA treatment the actin appeared to be fully depolymerized in control and NAA80-KO cells, and washout of the drug resulted in the recovery of actin filament structures, but the time of recovery was significantly delayed for NAA80-KO cells compared with control cells (Fig. S6), consistent with a direct role of actin Nt-acetylation in actin polymerization.. We next explored the in vitro effect of actin Nt-acetylation on the polymerization/depolymerization properties of actin alone or in the presence of some of the most common actin-assembly factors in cells. Cytoplasmic actin (a mixture of β and γ isoforms) was purified from control and NAA80-KO cells, and the presence or absence of Nt-acetylation was verified by Western blotting (Fig. 4A) (22). The ...
Dynamic actin network at the leading edge of the cell is linked to the extracellular matrix through focal adhesions (FAs), and at the same time it undergoes retrograde flow with different dynamics in two distinct zones: the lamellipodium (peripheral zone of fast flow), and the lamellum (zone of slow flow located between the lamellipodium and the cell body). Cell migration involves expansion of both the lamellipodium and the lamellum, as well as formation of new FAs, but it is largely unknown how the position of the boundary between the two flow zones is defined, and how FAs and actin flow mutually influence each other. We investigated dynamic relationship between focal adhesions and the boundary between the two flow zones in spreading cells. Nascent FAs first appeared in the lamellipodium. Within seconds after the formation of new FAs, the rate of actin flow decreased locally, and the lamellipodium/lamellum boundary advanced towards the new FAs. Blocking fast actin flow with cytochalasin D resulted in
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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Background Podocyte foot process effacement accompanied by actin cytoskeleton rearrangements is a cardinal feature of many progressive human proteinuric diseases. Results By microarray profiling of mouse glomerulus, SCHIP1 emerged as one of the most highly enriched transcripts. We detected Schip1 protein in the kidney glomerulus, specifically in podocytes foot processes. Functionally, Schip1 inactivation in zebrafish by morpholino knock-down results in foot process disorganization and podocyte loss leading to proteinuria. In cultured podocytes Schip1 localizes to cortical actin-rich regions of lamellipodia, where it forms a complex with Nherf2 and ezrin, proteins known to participate in actin remodeling stimulated by PDGF beta signaling. Mechanistically, overexpression of Schip1 in vitro causes accumulation of cortical F-actin with dissolution of transversal stress fibers and promotes cell migration in response to PDGF-BB stimulation. Upon actin disassembly by latrunculin A treatment, Schip1 ...
Nuclear actin participates in many essential cellular processes including gene transcription, chromatin remodelling and mRNA processing. Actin shuttles into and out the nucleus through the action of dedicated transport receptors importin-9 and exportin-6, but how this transport is regulated remains unclear. Here, we show that RASSF1A is a novel regulator of actin nucleocytoplasmic trafficking and is required for the active maintenance of nuclear actin levels through supporting binding of exportin-6 (XPO6) to RAN GTPase. RASSF1A (Ras association domain family 1 isoform A) is a tumour suppressor gene frequently silenced by promoter hypermethylation in all major solid cancers. Specifically, we demonstrate that endogenous RASSF1A localises to the nuclear envelope (NE) and is required for nucleocytoplasmic actin transport and the concomitant regulation of myocardin-related transcription factor A (MRTF-A), a co-activator of the transcription factor serum response factor (SRF). The RASSF1A/RAN/XPO6/nuclear
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TY - JOUR. T1 - mDia1 and formins. T2 - Screw cap of the actin filament. AU - Mizuno, Hiroaki. AU - Watanabe, Naoki. N1 - Copyright: Copyright 2013 Elsevier B.V., All rights reserved.. PY - 2012. Y1 - 2012. N2 - Formin homology proteins (formins) are actin nucleation factors which remain bound to the growing barbed end and processively elongate actin filament (F-actin). Recently, we have demonstrated that a mammalian formin mDia1 rotates along the long-pitch helix of Factin during processive elongation (helical rotation) by single-molecule fluorescence polarization. We have also shown processive depolymerization of mDia1-bound Factin during which helical rotation was visualized. In the cell where F-actins are highly cross-linked, formins should rotate during filament elongation. Therefore, when formins are tightly anchored to cellular structures, formins may not elongate F-actin. Adversely, helical rotation of formins might affect the twist of F-actin. Formins could thus control actin elongation ...
Molecular probes that individually recognize the 3′ nontranslated regions of six actin genes were utilized in RNA gel blot hybridizations to detect RNAs complementary to each gene in embryonic and adult tissues of Stronglyocentrotus purpuratus. In addition the probes were used in DNA excess filter hybridizations to estimate the relative contribution of the different actin genes. All six genes produce relatively stable mRNAs, and each displays a characteristic and distinct pattern of expression. On the basis of their expression in the egg, early embryos, or in adult coelomocytes, it is concluded that genes termed CyI, CyIIa, CyIIb, CyIIIa, and CyIIIb encode cytoskeletal actin proteins. Actin gene M gives rise to mRNAs that are found only in tissues containing muscle. Actin genes CyI, CyIIa, CyIIb, and M are expressed in both adult and embryonic tissues, giving rise to transcripts 2.1-2.2 kb in length. Expression of genes CyIIIa and CyIIIb is confined to the embryo. Gene CyIIIa provides the ...
TY - JOUR. T1 - Mutants in the Dictyostelium Arp2/3 complex and chemoattractant-induced actin polymerization. AU - Langridge, Paul D.. AU - Kay, Robert R.. PY - 2007/7/15. Y1 - 2007/7/15. N2 - We have investigated the role of the Arp2/3 complex in Dictyostelium cell chemotaxis towards cyclic-AMP and in the actin polymerization that is triggered by this chemoattractant. We confirm that the Arp2/3 complex is recruited to the cell perimeter, or into a pseudopod, after cyclic-AMP stimulation and that this is coincident with actin polymerization. This recruitment is inhibited when actin polymerization is blocked using latrunculin suggesting that the complex binds to pre-existing actin filaments, rather than to a membrane associated signaling complex. We show genetically that an intact Arp2/3 complex is essential in Dictyostelium and have produced partially active mutants in two of its subunits. In these mutants both phases of actin polymerization in response to cyclic-AMP are greatly reduced. One ...
The actin cytoskeleton is crucial for function and morphology of neuronal synapses. Moreover, altered regulation of the neuronal actin cytoskeleton has been implicated in neuropsychiatric diseases such as autism spectrum disorder (ASD). Myosin XVI is a neuronally expressed unconventional myosin known to bind the WAVE regulatory complex (WRC), a regulator of filamentous actin (F-actin) polymerization. Notably, the gene encoding the myosins heavy chain (MYO16) shows genetic association with neuropsychiatric disorders including ASD. Here, we investigated whether myosin XVI plays a role for actin cytoskeleton regulation in the dendritic spines of cerebellar Purkinje cells (PCs), a neuronal cell type crucial for motor learning, social cognition and vocalization. We provide evidence that both myosin XVI and the WRC component WAVE1 localize to PC spines. Fluorescence recovery after photobleaching (FRAP) analysis of GFP-actin in cultured PCs shows that Myo16 knockout as well as PC-specific Myo16 knockdown,
TGF-β-induced antimitotic signals are highly regulated during cell proliferation under normal and pathological conditions, such as liver regeneration and cancer. Up-regulation of the transcriptional cofactors Ski and SnoN during liver regeneration may favor hepatocyte proliferation by inhibiting TGF-β signals. In this study, we found a novel mechanism that regulates Ski protein stability through TGF-β and G protein-coupled receptor (GPCR) signaling. Ski protein is distributed between the nucleus and cytoplasm of normal hepatocytes, and the molecular mechanisms controlling Ski protein stability involve the participation of actin cytoskeleton dynamics. Cytoplasmic Ski is partially associated with actin and localized in cholesterol-rich vesicles. Ski protein stability is decreased by TGF-β/Smads, GPCR/Rho signals, and actin polymerization, whereas GPCR/cAMP signals and actin depolymerization promote Ski protein stability. In conclusion, TGF-β and GPCR signals differentially regulate Ski ...
FIG 6 In vitro interaction of occidiofungin with F- and G-actin. (a) Affinity pulldown of actin using alkyne-OF. Lane 1, ladder; lane 2, 100 ng pure F-actin; lane 3, 100 ng pure G-actin; lane 4, empty; lane 5, F-actin treated with alkyne-OF; lane 6, F-actin treated with native occidiofungin; lane 7, F-actin treated with DMSO; lane 8, G-actin treated with alkyne-OF; lane 9, G-actin treated with native occidiofungin; lane 10, G-actin treated with DMSO. (b) Fluorescence microscopy of the effect of occidiofungin treatment on actin filaments visualized by fluorescently labeled phalloidin. (A) Actin filaments treated with solvent blank (DMSO). (B) Actin/native occidiofungin (24 μg actin:4 μg native occidiofungin). (C) Actin/native occidiofungin (24 μg actin:8 μg native occidiofungin). Scale bar, 5 µm. ...
Title:[Comparison of intracellular actin of thymosin alpha-1 and thymic serum factor].,Author:Deschaux P,Doublet A,Fontanges R,Journal:C R Seances Acad Sci III,1982/1/25;294(4):207-10.,Publication typ...
University of Helsinki, Faculty of Biosciences, Department of Biological and Environmental Sciences, Division of genetics and Institute of Biotechnology. The actin cytoskeleton is essential for a large variety of cell biological processes. Actin exists in either a monomeric or a filamentous form, and it is very important for many cellular functions that the local balance between these two actin populations is properly regulated. A large number of proteins participate in the regulation of actin dynamics in the cell, and twinfilin, one of the proteins examined in this thesis, belongs to this category. The second level of regulation involves proteins that crosslink or bundle actin filaments, thereby providing the cell with a certain shape. α-Actinin, the second protein studied, mainly acts as an actin crosslinking protein. Both proteins are conserved in organisms ranging from yeast to mammals. In this thesis, the roles of twinfilin and α-actinin in development were examined using Drosophila ...
The myristoylated form of c-Abl protein, as well as the P210bcr/abl protein, have been shown by indirect immunofluorescence to associate with F-actin stress fibers in fibroblasts. Analysis of deletion mutants of c-Abl stably expressed in fibroblasts maps the domain responsible for this interaction to the extreme COOH-terminus of Abl. This domain mediates the association of a heterologous protein with F-actin filaments after microinjection into NIH 3T3 cells, and directly binds to F-actin in a cosedimentation assay. Microinjection and cosedimentation assays localize the actin-binding domain to a 58 amino acid region, including a charged motif at the extreme COOH-terminus that is important for efficient binding. F-actin binding by Abl is calcium independent, and Abl competes with gelsolin for binding to F- actin. In addition to the F-actin binding domain, the COOH-terminus of Abl contains a proline-rich region that mediates binding and sequestration of G-actin, and the Abl F- and G-actin binding ...
Each myofibril consists of a large number of sarcomeres, the muscle cells smallest functional units.. Each sarcomere consists of a Z-disc in each end and an A-band in the middle. Actin filaments attached to the Z-discs and myosin filaments form the A band. It is the repetitive A-bands that give the characteristic transverse muscle strips seen under a microscope.. Actin and myosin filaments are organised so every myosin filament is surrounded by six actin filaments. The muscle contraction is a result of myosin filaments climbing on actin filaments in each sarcomere.. The actin filaments comprise of several spherical proteins in long helical chains. They consist of the proteins actin, tropomyocin and a troponin complex. All these are essential for muscle contraction.. The myosin filaments are an accumulation of approximately 300 elongated myosin molecules. Each of these proteins has a head on one end. The myosin heads function is to bind and slide on the actin filaments that lie parallel. As ...
Actin plays important roles in many biological processes, such as establishing cell polarization, accommodating protruding and retracting activities of motile cells, maintaining the physical integrity of the cell, and sensing environmental forces. All these processes are facilitated by the dynamical and mechanical properties of actin filaments, and their ability to exert or resist against forces generated in a cellular environment.. Actin filaments can assemble into a variety of architectures, including branched and crosslinked networks, parallel bundles, and anti-parallel contractile fibers. These structures provide architectural specificities for different regions of the cell, and can also organize into more complex actin-based machineries. We aim to understand how the native molecular architectures of actin-based cellular processes give rise to force generation and rigidity-sensing. We use cryo-electron tomography, and develop methodologies allowing for quantitative analysis of cellular actin ...
We describe the preparation of novel fluorescent derivatives of rabbit muscle actin and bovine tubulin, and the use of these derivatives to study the behaviour of actin filaments and microtubules in living Drosophila embryos, in which the nuclei divide at intervals of 8 to 21 min. The fluorescently labelled proteins appear to function normally in vitro and in vivo, and they allow continuous observation of the cytoskeleton in living embryos without perturbing development. By coinjecting labelled actin and tubulin into the early syncytial embryo, the spatial relationships between the distinct filament networks that they form can be followed second by second. The dynamic rearrangements of actin filaments and microtubules observed confirms and extends results obtained from previous studies, in which fixation techniques and specific staining were used to visualize the cytoskeleton in the Drosophila embryo. However, no tested fixation method produces an exact representation of the in vivo microtubule ...
Gelsolin is an actin-modulating protein that severs F-actin, caps the barbed ends of actin filaments preventing monomer exchange, and promotes the nucleation step of actin polymerisation [(PUBMED:14527663), (PUBMED:3023087)]. It can be regulated by Ca2+ and phosphoinositides [(PUBMED:3027569)]. The interaction between gelsolin and tropomyosin modulates actin dynamics [(PUBMED:23844991)]. Gelsolin also plays a role in ciliogenesis [(PUBMED:20393563)]. The structure of gelsolin has been solved [(PUBMED:9288746)]. Villin is an actin-binding protein that is found in a variety of tissues. It is able to bind to the barbed end of actin filaments with high affinity and can sever filaments [(PUBMED:3087992)]. In addition, villins activity is important for actin bundling in certain cell types [(PUBMED:2256904)]. It was first isolated as a major component of the core of intestinal microvilli [(PUBMED:287075)].. Villin/gelsolin family includes other actin-binding proteins such as severin and supervillin ...
Gelsolin is an actin-modulating protein that severs F-actin, caps the barbed ends of actin filaments preventing monomer exchange, and promotes the nucleation step of actin polymerisation [ (PUBMED:14527663) (PUBMED:3023087) ]. It can be regulated by Ca2+ and phosphoinositides [ (PUBMED:3027569) ]. The interaction between gelsolin and tropomyosin modulates actin dynamics [ (PUBMED:23844991) ]. Gelsolin also plays a role in ciliogenesis [ (PUBMED:20393563) ]. The structure of gelsolin has been solved [ (PUBMED:9288746) ]. Villin is an actin-binding protein that is found in a variety of tissues. It is able to bind to the barbed end of actin filaments with high affinity and can sever filaments [ (PUBMED:3087992) ]. In addition, villins activity is important for actin bundling in certain cell types [ (PUBMED:2256904) ]. It was first isolated as a major component of the core of intestinal microvilli [ (PUBMED:287075) ]. Villin/gelsolin family includes other actin-binding proteins such as severin and ...
In striated muscle the actin cytoskeleton is differentiated into myofibrils. or Axitinib muscles diseases. Therefore proper regulation of actin dynamics in striated muscle is crucial for maintenance and assembly of functional myofibrils. Recent studies have got recommended that both enhancers of actin dynamics and stabilizers of actin filaments are essential for sarcomeric actin company. Further investigation from the regulatory system of actin dynamics in striated muscles should be an integral to focusing on how myofibrils develop and work. ? 2010 Wiley-Liss Inc. continues to be used being a model to review set up and function of cross-striated myofibrils [Fyrberg and Beall 1990 Many invertebrates including nematodes annelids and molluscs possess obliquely striated muscles where sarcomeres are aligned obliquely towards the Z-band-like buildings [Rosenbluth 1965 Your body wall structure muscles from the nematode is normally a consultant example and continues to be thoroughly studied using ...
TY - JOUR. T1 - Competition for actin between two distinct F-actin networks defines a bistable switch for cell polarization. AU - Lomakin, Alexis J.. AU - Lee, Kun Chun. AU - Han, Sangyoon J.. AU - Bui, Duyen A.. AU - Davidson, Michael. AU - Mogilner, Alex. AU - Danuser, Gaudenz. PY - 2015/11/1. Y1 - 2015/11/1. N2 - Symmetry-breaking polarization enables functional plasticity of cells and tissues and is yet not well understood. Here we show that epithelial cells, hard-wired to maintain a static morphology and to preserve tissue organization, can spontaneously switch to a migratory polarized phenotype after relaxation of the actomyosin cytoskeleton. We find that myosin II engages actin in the formation of cortical actomyosin bundles and thus makes it unavailable for deployment in the process of dendritic growth normally driving cell motility. Under low-contractility regimes, epithelial cells polarize in a front-back manner owing to the emergence of actin retrograde flows powered by dendritic ...
TY - JOUR. T1 - Evidence That Actin Depolymerization Protects Hippocampal Neurons against Excitotoxicity by Stabilizing [Ca2+]i. AU - Furukawa, Katsutoshi. AU - Smith-Swintosky, Virginia L.. AU - Mattson, Mark P.. PY - 1995/6. Y1 - 1995/6. N2 - Calcium influx through glutamate receptors and voltage-dependent channels mediates an array of functional and structural responses in neurons. However, unrestrained Ca2+ influx can injure and kill neurons; a mechanism implicated in both acute and chronic neurodegenerative disorders. Data reported here indicate that depolymerization of actin filaments can stabilize intracellular free calcium levels ([Ca2+]i) and protect hippocampal neurons against excitotoxic injury. Studies with fluorescein-labeled phalloidin showed that cytochalasin D and glutamate each induced actin filament depolymerization. The microfilament-disrupting agent cytochalasin D protected cultured rat hippocampal neurons against glutamate toxicity, whereas the actin filament-stabilizing ...
The ,italic,ampA,/italic, gene encodes a secreted protein that modulates cell adhesion, actin polymerization, endocytosis, and cell migration. AmpA is secreted into the supernatant during development, and remains cell associated during growth. AmpA loss in growing cells results in an increase in cell adhesion, and a reduction in F actin. Over expression of AmpA reduces adhesion and increases F actin. As a result of these changes in the cytoskeleton and in adhesion, I have shown AmpA influences cell migration. AmpA knockout cells are defective in migration on top of agar compared to wild type. AmpA over expressing cells migrate better than wild type on top of agar. This defect in the knockout can be rescued by placing the cells in a 3D environment where they migrate under agar. Knockout cells migrate better than wild type under these conditions and over expressing cells migrate about the same as wild type. In order to visualize actin dynamics in live cells, wild type, AmpA KO and AmpA ...
CiteSeerX - Scientific documents that cite the following paper: Adenovirus endocytosis requires actin cytoskeleton reorganization mediated by Rho family Gtpases,
The C-type lectin-like receptor 2 (CLEC-2)activates platelets through Src and Syk tyrosine kinases via a single cytoplasmic YxxL motif known as a hem immunoreceptor tyrosine-based activation motif (hemITAM).Here, we demonstrate using sucrose gradient ultracentrifugation and methyl--cyclodextrin treatment that CLEC-2 translocates to lipid rafts upon ligand engagement and that translocation is essential for hemITAM phosphorylation and signal initiation. HemITAM phosphorylation, but not translocation, is also critically dependent on actin polymerization,Rac1 activation, and release of ADP and thromboxane A2 (TxA2). The role of ADP and TxA2 in mediating hosphorylation is dependent on ligand engagement and rac activation but is independent of platelet aggregation. In contrast,tyrosine phosphorylation of the GPVIFcR -chain ITAM, which has 2 YxxL motifs,is independent of actin polymerization and secondary mediators. These results reveal a unique series of proximal events in CLEC-2 phosphorylation ...
In chronic active hepatitis, very strong alpha-SMA staining was detected at the site of piecemeal necrosis and adjacent lobules. A-SMA expression was decreased in some cases after interferon treatment. In cases of transplanted liver biopsies, expression of intralobular alpha-SMA was diffusely increased but showed no correlation with degree of acute rejection. Cirrhotic livers revealed strong alpha-SMA positivity in fibrous septae as well as in the perisinusoidal space of intact hepatocytes at the leading edge of fibrosis. Interlobular bile ducts were concentrically circumscribed by alpha-SMA positive cells in cases of intrahepatic cholelithiasis. In trabecular type hepatocellular carcinomas, most sinusoidal lining cells were positive for alpha-SMA. Most intralobular alpha-SMA positive cells represent, if not all, perisinusoidal cells (PSCs) which are involved in intralobular fibrogenesis in various liver diseases. PMID: 8305144. ...
Purpose: : PAAs are temporary polygonal, hub and spoke arrangements of actin seen in the first few hours of tissue culture while the cells are settling but then are lost. CLANs are also hub and spoke arrangements of actin that are slowly induced in confluent cultures by steroids, TGFbeta and others and persist. We wished to determine whether or not CLANs and PAAs are one in the same thing so that rapidly forming PAAs can legitimately be used as a model for the slower forming CLANs that we know to form in vivo and are associated with glaucoma in a way that is poorly understood. Methods: : We stain actin in TM cells both in vitro and in situ using phalloid-FITC and image cells either with conventional immunofluorescence or by confocal microscopy. We have a large collection of PAAs and CLANs images and from these over 50 images were selected and handed over in a masked fashion to our reading team who used Image J Software (NIH) to measure CLAN and PAA territories, height, circularity, incidence of ...
Manié S, Schmid-Alliana A, Kubar J, Ferrua B, Rossi B 1993 Disruption of microtubule network in human monocytes induces expression of interleukin-1 but not that of interleukin-6 nor tumor necrosis factor-α: Involvement of protein kinase a stimulation J Biol Chem 268:13675-13681 ...
The studies presented here clearly demonstrated that TGF-β1 triggers the nuclear translocation of MRTFs, which activates the two parallel pathways during EMT (Fig. 10 J). One pathway up-regulates the expression of EMT-regulating genes, such as slug, via MRTFs, Smad3, and GCCG-like motifs, leading to dissociation of cell-cell contacts. The other up-regulates the expression of actin cytoskeletal genes via MRTFs, SRF, and CArG box, resulting in remodeling of the actin cytoskeleton.. Recent studies demonstrate that MRTFs associate with monomeric G-actin through their RPEL motifs, which anchor MRTFs in the cytoplasm (Miralles et al., 2003; Posern et al., 2004). Activated Rho reduces the cytoplasmic G-actin pool by enhancing actin polymerization, and then triggers the dissociation of MRTFs from G-actin, resulting in the nuclear translocation of MRTFs. TGF-β1 stimulation enhances the Rho activity in many kinds of epithelial cell lines (Bhowmick et al., 2001, 2003; Tian et al., 2003). We demonstrated ...
Abbkine Scientific Co. Ltd is known for making quality life science products and tools and it recently announced the official launch of its new antibody - the Anti-Plant Actin Mouse Monoclonal Antibody (3T3).. The antibody otherwise known as AT3G12110 antibody is a Plant Actin Antibody, which is an essential component of cell cytoskeleton. The substance also plays a critical role in the streaming of cytoplasmic, determination of cell shape, cell division and extension growth.. The product is available in a liquid solution and hosted by mouse hence, Plant Actin Mouse mAb. The antibody is also a Recombinant Protein immunogen, with plant reactivity. The antibody like many of its other counterparts is affinity-purified from mouse ascites using specific immunogen by affinity-chromatography.. The Anti-Plant Actin Mouse Monoclonal Antibody (3T3) is made solely for research purpose and not intended for clinical or human use. It can also be stored for as long as one year at -20°C from date of ...
The mechanical properties of a cell are defined mainly by the cytoskeleton. One contributor within this three-dimensional structure is the actin cortex which is located underneath the lipid bilayer. It forms a nearly isotropic and densely cross-linked protein network. We present a continuum mechanical formulation for describing the mechanical properties of in vitro model systems based on their micro-structure, i.e. the behavior of a single filament and its spatial arrangement. The network is considered elastic, viscous effects being neglected. Filamentous actin is a biopolymer with a highly nonlinear force-stretch relationship. This can be well described by a worm-like chain model that includes extensibility of the filament, which we call the . β-model. A comparison with experimental data shows good agreement with values for the physically interpretable parameters. To make these properties applicable to three dimensions we used a non-affine micro-sphere network, which accounts for filaments, ...
p,Giardia intestinalis, a human intestinal parasite and member of what is perhaps the earliest-diverging eukaryotic lineage, contains the most divergent eukaryotic actin identified to date and is the first eukaryote known to lack all canonical actin-binding proteins (ABPs). We sought to investigate the properties and functions of the actin cytoskeleton in Giardia to determine whether Giardia actin (giActin) has reduced or conserved roles in core cellular processes. In vitro polymerization of giActin produced filaments, indicating that this divergent actin is a true filament-forming actin. We generated an anti-giActin antibody to localize giActin throughout the cell cycle. GiActin localized to the cortex, nuclei, internal axonemes, and formed C-shaped filaments along the anterior of the cell and a flagella-bundling helix. These structures were regulated with the cell cycle and in encysting cells giActin was recruited to the Golgi-like cyst wall processing vesicles. Knockdown of giActin ...
The Corynebacterium glutamicum ATCC 13032 prophage CGP3 encodes an actin-like protein, AlpC that was shown to be involved in viral DNA transport and efficient viral DNA replication. AlpC binds to an adapter, AlpA that in turn binds to specific DNA sequences, termed alpS sites. Thus, the AlpAC system is similar to the known plasmid segregation system ParMRS. So far it is unclear how the AlpACS system mediates DNA transport and, whether AlpA and AlpC functionally interact. We show here that AlpA modulates AlpC filamentation dynamics in a dual way. Unbound AlpA stimulates AlpC filament disassembly, while AlpA bound to alpS sites allows for AlpC filament formation. Based on these results we propose a simple search and capture model that explains DNA segregation by viral AlpACS DNA segregation system. ...
Classic pulse-chase studies have shown that actin is conveyed in slow axonal transport, but the mechanistic basis for this movement is unknown. Recently, we reported that axonal actin was surprisingly dynamic, with focal assembly/disassembly events (actin hotspots) and elongating polymers along the axon shaft (actin trails). Using a combination of live imaging, superresolution microscopy, and modeling, in this study, we explore how these dynamic structures can lead to processive transport of actin. We found relatively more actin trails elongated anterogradely as well as an overall slow, anterogradely biased flow of actin in axon shafts. Starting with first principles of monomer/filament assembly and incorporating imaging data, we generated a quantitative model simulating axonal hotspots and trails. Our simulations predict that the axonal actin dynamics indeed lead to a slow anterogradely biased flow of the population. Collectively, the data point to a surprising scenario where local assembly ...
SUMMARY, EXPLANATION AND LIMITATIONS:. Actin is an abundant cytoskeletal protein found in all cells. The proteins 42 kD peptide chain assumes two physical forms: globular actin, which may serve as a cytoplasmic storage pool, and fibrous actin, which, in conjunction with myosin, generates muscle contraction. In non-muscle cells, actin appears to be involved in a variety of functions, such as cell motility, exocytosis, and phagocytosis.. Clone: 5C5,F8,C7. Isotype: IgM. Immunogen: N-Terminal decapeptide of alpha skeletal muscle isoform of actin.. Staining pattern: Cytoplasmic.. Positive control: Tissue sample from skeletal muscle.. APPLICATIONS:. This antibody is designed for the specific localization of human Actin, Skeletal Muscle using IHC techniques in formalin-fixed, paraffin-embedded tissue sections.. ...
for the thin filaments on either side of the Z disc 8. Muscle contraction: sarcomere will shorten in length as Z discs come closer together and size of the H band decreases; the thin filaments are overlapping the thick filaments. 9. Sliding filament hypothesis: (1). Myosin heads bind ATP and split it forming ADP and Pi (2). Myosin heads bind to sites on the actin filaments (3). Myosin heads release the Pi allowing the head to bend toward the A band and Pulling the actin filaments with it; this is the power stroke (4).At end of power stroke, myosin head binds a new ATP and releases ADP; myosin head breaks away from the actin filament 10. Cross bridges: temporary union between the myosin and actin filaments 11. Troponin: protein that binds tropomyosin to actin; also is attracted to Ca+2 ions Tropomyosin: double strand of protein; blocks actin binding sites preventing myosin attachment 12. Neuromuscular junction: (1). Neuron releases acetylcholine which binds to Ach receptors on motor end Plate of ...
We have found that Ste20 or Cla4 is required to polarize the actin cytoskeleton and initiate bud emergence. Whereas mutants lacking either kinase can carry out these processes, loss of Ste20 and Cla4 blocks these events, displaying phenotypes like those of cdc42-1 mutants ( Adams et al. 1990). Because results presented here and elsewhere indicate that Cla4 and Ste20 interact and colocalize with Cdc42 at sites of polarized growth ( Adams et al. 1990; Peter et al. 1996; Benton et al. 1997; Leberer et al. 1997), these PAK homologues function as direct signaling effectors of Cdc42 in pathways that promote bud emergence and actin polarization in G1. In contrast, Ste20 and Cla4 are not required for isotropic growth or progression of the nuclear division cycle, indicating that they have primary roles in cell and actin polarization.. Several observations indicate that Ste20 and Cla4 promote bud emergence by executing functions that are at least partially distinct from those carried out by the Cdc42 ...
APPL1- and RAB5-positive signaling endosomes play a crucial role in the activation of AKT in response to extracellular stimuli. Myosin VI (MYO6) and two of its cargo adaptor proteins, GIPC and TOM1/TOM1L2, localize to these peripheral endosomes and mediate endosome association with cortical actin filaments. Loss of MYO6 leads to the displacement of these endosomes from the cell cortex and accumulation in the perinuclear space. Depletion of this myosin not only affects endosome positioning, but also induces actin and lipid remodeling consistent with endosome maturation, including accumulation of F-actin and the endosomal lipid PI(3)P. These processes acutely perturb endosome function, as both AKT phosphorylation and RAC-dependent membrane ruffling were markedly reduced by depletion of either APPL1 or MYO6. These results place MYO6 and its binding partners at a central nexus in cellular signaling linking actin dynamics at the cell surface and endosomal signaling in the cell cortex ...
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SMARCB1 (ENST00000644036.1) at chr22:23786946-23838008 - Homo sapiens SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (SMARCB1), transcript variant 1, mRNA. (from RefSeq NM_003073) SMARCB1 (ENST00000629690.2) at chr22_KI270879v1_alt:23325-70878 - Homo sapiens SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (SMARCB1), transcript variant 4, mRNA. (from RefSeq NM_001362877) SMARCB1 (ENST00000647057.1) at chr22:23786983-23834505 - SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (from HGNC SMARCB1) SMARCB1 (ENST00000646911.1) at chr22:23787258-23826248 - SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (from HGNC SMARCB1) SMARCB1 (ENST00000646723.1) at chr22:23787182-23834270 - SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1 (from HGNC SMARCB1) SMARCB1 ...