scholarly journals Viscoelastic properties of vimentin compared with other filamentous biopolymer networks.

1991 ◽  
Vol 113 (1) ◽  
pp. 155-160 ◽  
Author(s):  
P A Janmey ◽  
U Euteneuer ◽  
P Traub ◽  
M Schliwa
Keyword(s):  
Viscoelastic Properties ◽  
Intermediate Filament Protein ◽  
Linear Polymers ◽  
Cell Integrity ◽  
Interphase Cell ◽  
Shear Moduli ◽  
Lower Shear ◽  
Cytoplasmic Filaments ◽  
Filament Protein

The cytoplasm of vertebrate cells contains three distinct filamentous biopolymers, the microtubules, microfilaments, and intermediate filaments. The basic structural elements of these three filaments are linear polymers of the proteins tubulin, actin, and vimentin or another related intermediate filament protein, respectively. The viscoelastic properties of cytoplasmic filaments are likely to be relevant to their biologic function, because their extreme length and rodlike structure dominate the rheologic behavior of cytoplasm, and changes in their structure may cause gel-sol transitions observed when cells are activated or begin to move. This paper describes parallel measurements of the viscoelasticity of tubulin, actin, and vimentin polymers. The rheologic differences among the three types of cytoplasmic polymers suggest possible specialized roles for the different classes of filaments in vivo. Actin forms networks of highest rigidity that fluidize at high strains, consistent with a role in cell motility in which stable protrusions can deform rapidly in response to controlled filament rupture. Vimentin networks, which have not previously been studied by rheologic methods, exhibit some unusual viscoelastic properties not shared by actin or tubulin. They are less rigid (have lower shear moduli) at low strain but harden at high strains and resist breakage, suggesting they maintain cell integrity. The differences between F-actin and vimentin are optimal for the formation of a composite material with a range of properties that cannot be achieved by either polymer alone. Microtubules are unlikely to contribute significantly to interphase cell rheology alone, but may help stabilize the other networks.

scholarly journals Purification of desmin from adult mammalian skeletal muscle

1981 ◽  
Vol 195 (2) ◽  
pp. 345-356 ◽  
Author(s):  
J M O'Shea ◽  
R M Robson ◽  
M K Hartzer ◽  
T W Huiatt ◽  
W E Rathbun ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Average Diameter ◽  
Intermediate Filament Protein ◽  
Mammalian Skeletal Muscle ◽  
Cytoskeletal Function ◽  
10 Nm Filaments ◽  
And Function ◽  
Filament Protein

A method has been developed for preparation of purified desmin from mature mammalian (porcine) skeletal muscle. A crude desmin-containing fraction was prepared by modification of procedures used for isolation of smooth-muscle intermediate-filament protein [Small & Sobieszek (1977) J. Cell Sci. 23, 243-268]. The desmin was extracted in 1 M-acetic acid/20 mM-NaCl at 4 degrees C for 15h from the residue remaining after actomyosin extraction from washed myofibrils. Successive chromatography on hydroxyapatite and DEAE-Sepharose CL-6B in 6M-urea yielded desmin that was routinely more than 97% 55 000-dalton protein and that had no detectable actin contamination. Removal of urea by dialysis against 10mM-Tris/acetate (pH 8.5)/1 mM dithioerythritol and subsequent clarification at 134 000 g (rav. 5.9 cm) for 1 h results in a clear desmin solution. Dialysis of purified desmin against 100 mM-NaCl/1 mM-MgCl2/10 mM-imidazole/HCl, pH 7.0, at 2 degrees C resulted in the formation of synthetic desmin filaments have an average diameter of 9-11.5 nm. The present studies demonstrate that the relatively small amount of desmin in mature skeletal muscle can be isolated in sufficient quantity and purity to permit detailed studies of its properties and function. Although 10nm filaments have not been unequivocally demonstrated in mature muscle in vivo, that the purified skeletal-muscle desmin will form 10 nm filaments in vitro lends support to their possible existence and cytoskeletal function in mature skeletal-muscle cells.

scholarly journals Cdk5 Regulates the Organization of Nestin and Its Association with p35

2003 ◽  
Vol 23 (14) ◽  
pp. 5090-5106 ◽  
Author(s):  
Cecilia M. Sahlgren ◽  
Andrey Mikhailov ◽  
Samuli Vaittinen ◽  
Hanna-Mari Pallari ◽  
Hannu Kalimo ◽  
...  
Keyword(s):  
Ectopic Expression ◽  
Dominant Negative ◽  
Myoblast Differentiation ◽  
Intermediate Filament Protein ◽  
Nestin Expression ◽  
Specific Expression ◽  
Elevated Expression ◽  
Myoblast Cell ◽  
Filament Protein

ABSTRACT The intermediate filament protein nestin is characterized by its specific expression during the development of neuronal and myogenic tissues. We identify nestin as a novel in vivo target for cdk5 and p35 kinase, a critical signaling determinant in development. Two cdk5-specific phosphorylation sites on nestin, Thr-1495 and Thr-316, were established, the latter of which was used as a marker for cdk5-specific phosphorylation in vivo. Ectopic expression of cdk5 and p35 in central nervous system progenitor cells and in myogenic precursor cells induced elevated phosphorylation and reorganization of nestin. The kinetics of nestin expression corresponded to elevated expression and activation of cdk5 during differentiation of myoblast cell cultures and during regeneration of skeletal muscle. In the myoblasts, a disassembly-linked phosphorylation of Thr-316 indicated active phosphorylation of nestin by cdk5. Moreover, cdk5 occurred in physical association with nestin. Inhibition of cdk5 activity—either by transfection with dominant-negative cdk5 or by using a specific cdk5 inhibitor—blocked myoblast differentiation and phosphorylation of nestin at Thr-316, and this inhibition markedly disturbed the organization of nestin. Interestingly, the interaction between p35, the cdk5 activator, and nestin appeared to be regulated by cdk5. In differentiating myoblasts, p35 was not complexed with nestin phosphorylated at Thr-316, and inhibition of cdk5 activity during differentiation induced a marked association of p35 with nestin. These results demonstrate that there is a continuous turnover of cdk5 and p35 activity on a scaffold formed by nestin. This association is likely to affect the organization and operation of both cdk5 and nestin during development.

scholarly journals Artemisinins target the intermediate filament protein vimentin for human cytomegalovirus inhibition

2020 ◽  
Vol 295 (44) ◽  
pp. 15013-15028 ◽  
Author(s):  
Sujayita Roy ◽  
Arun Kapoor ◽  
Fei Zhu ◽  
Rupkatha Mukhopadhyay ◽  
Ayan Kumar Ghosh ◽  
...  
Keyword(s):  
Intermediate Filament ◽  
Hcmv Infection ◽  
Intermediate Filament Protein ◽  
Biological Assays ◽  
Human Foreskin Fibroblasts ◽  
Hcmv Replication ◽  
Human Cmv ◽  
Filament Protein

The antimalarial agents artemisinins inhibit cytomegalovirus (CMV) in vitro and in vivo, but their target(s) has been elusive. Using a biotin-labeled artemisinin, we identified the intermediate filament protein vimentin as an artemisinin target, validated by detailed biochemical and biological assays. We provide insights into the dynamic and unique modulation of vimentin, depending on the stage of human CMV (HCMV) replication. In vitro, HCMV entry and viral progeny are reduced in vimentin-deficient fibroblasts, compared with control cells. Similarly, mouse CMV (MCMV) replication in vimentin knockout mice is significantly reduced compared with controls in vivo, confirming the requirement of vimentin for establishment of infection. Early after HCMV infection of human foreskin fibroblasts vimentin level is stable, but as infection proceeds, vimentin is destabilized, concurrent with its phosphorylation and virus-induced calpain activity. Intriguingly, in vimentin-overexpressing cells, HCMV infection is reduced compared with control cells. Binding of artesunate, an artemisinin monomer, to vimentin prevents virus-induced vimentin degradation, decreasing vimentin phosphorylation at Ser-55 and Ser-83 and resisting calpain digestion. In vimentin-deficient fibroblasts, the anti-HCMV activity of artesunate is reduced compared with controls. In summary, an intact and stable vimentin network is important for the initiation of HCMV replication but hinders its completion. Artesunate binding to vimentin early during infection stabilizes it and antagonizes subsequent HCMV-mediated vimentin destabilization, thus suppressing HCMV replication. Our target discovery should enable the identification of vimentin-binding sites and compound moieties for binding.

Viscoelastic Properties of Living Human Brain by Local Frequency Estimation Applied to Distortional Wave Fields

2012 ◽  
Author(s):  
Erik H. Clayton ◽  
Guy M. Genin ◽  
Philip V. Bayly
Keyword(s):  
Viscoelastic Properties ◽  
Frequency Estimation ◽  
Equations Of Motion ◽  
Wave Fields ◽  
Shear Moduli ◽  
Lossy Medium ◽  
Displacement Wave ◽  
Magnetic Resonance Imaging Mri ◽  
Elastic Shear

The use of magnetic resonance imaging (MRI) to characterize the biomechanical material properties of tissue in vivo is an emerging application. Local frequency estimation (LFE) [1] has been used to locally extract the wavenumber κ from displacement wave fields in order to estimate the elastic shear modulus via the well-known phase velocity relation [2,3]. LFE-based inversion is attractive because it allows material parameters to be estimated without explicitly invoking the equations of motion, thus obviating the need to numerically compute the Laplacian. In this study, viscoelastic properties of brain tissue at multiple frequencies were obtained by local frequency estimation (LFE) applied to distortional wave fields. This avoids artifacts from the presence of unmodeled longitudinal waves. By use of the equation describing planar distortional wave propagation in a lossy medium, the viscoelastic shear moduli were approximated.

scholarly journals Desmin mediates TNF-α–induced aggregate formation and intercalated disk reorganization in heart failure

2008 ◽  
Vol 181 (5) ◽  
pp. 761-775 ◽  
Author(s):  
Panagiota Panagopoulou ◽  
Constantinos H. Davos ◽  
Derek J. Milner ◽  
Emily Varela ◽  
JoAnn Cameron ◽  
...  
Keyword(s):  
Left Ventricular ◽  
Intermediate Filament Protein ◽  
Caspase Cleavage ◽  
Tnf Α ◽  
Caspase 6 ◽  
Underlying Mechanisms ◽  
Factor Α ◽  
Filament Protein ◽  
Intercalated Disk

We explored the involvement of the muscle-specific intermediate filament protein desmin in the model of tumor necrosis factor α (TNF-α)–induced cardiomyopathy. We demonstrate that in mice overexpressing TNF-α in the heart (α–myosin heavy chain promoter-driven secretable TNF-α [MHCsTNF]), desmin is modified, loses its intercalated disk (ID) localization, and forms aggregates that colocalize with heat shock protein 25 and ubiquitin. Additionally, other ID proteins such as desmoplakin and β-catenin show similar localization changes in a desmin-dependent fashion. To address underlying mechanisms, we examined whether desmin is a substrate for caspase-6 in vivo as well as the implications of desmin cleavage in MHCsTNF mice. We generated transgenic mice with cardiac-restricted expression of a desmin mutant (D263E) and proved that it is resistant to caspase cleavage in the MHCsTNF myocardium. The aggregates are diminished in these mice, and D263E desmin, desmoplakin, and β-catenin largely retain their proper ID localization. Importantly, D263E desmin expression attenuated cardiomyocyte apoptosis, prevented left ventricular wall thinning, and improved the function of MHCsTNF hearts.

scholarly journals A promiscuous biotin ligase fusion protein identifies proximal and interacting proteins in mammalian cells

2012 ◽  
Vol 196 (6) ◽  
pp. 801-810 ◽  
Author(s):  
Kyle J. Roux ◽  
Dae In Kim ◽  
Manfred Raida ◽  
Brian Burke
Keyword(s):  
Fusion Protein ◽  
Mammalian Cells ◽  
Nuclear Lamina ◽  
Intermediate Filament Protein ◽  
Structural Element ◽  
Affinity Capture ◽  
Cellular Environment ◽  
A New Technique ◽  
Filament Protein

We have developed a new technique for proximity-dependent labeling of proteins in eukaryotic cells. Named BioID for proximity-dependent biotin identification, this approach is based on fusion of a promiscuous Escherichia coli biotin protein ligase to a targeting protein. BioID features proximity-dependent biotinylation of proteins that are near-neighbors of the fusion protein. Biotinylated proteins may be isolated by affinity capture and identified by mass spectrometry. We apply BioID to lamin-A (LaA), a well-characterized intermediate filament protein that is a constituent of the nuclear lamina, an important structural element of the nuclear envelope (NE). We identify multiple proteins that associate with and/or are proximate to LaA in vivo. The most abundant of these include known interactors of LaA that are localized to the NE, as well as a new NE-associated protein named SLAP75. Our results suggest BioID is a useful and generally applicable method to screen for both interacting and neighboring proteins in their native cellular environment.

Cytokeratin expression in rat mesothelial cells in vitro is controlled by the extracellular matrix

1990 ◽  
Vol 95 (1) ◽  
pp. 97-107
Author(s):  
A.M. Mackay ◽  
R.P. Tracy ◽  
J.E. Craighead
Keyword(s):  
Extracellular Matrix ◽  
Basement Membrane ◽  
Intermediate Filament ◽  
Culture Conditions ◽  
Mesothelial Cells ◽  
Intermediate Filament Protein ◽  
Cellular Contact ◽  
Filament Protein

Rat mesothelial cells co-express vimentin and the simple epithelial cytokeratins. While cytokeratins predominate in situ, under most culture conditions vimentin is the major intermediate filament protein of the cells. This loss of cytokeratin production upon culture can be partly prevented by growing mesothelial cells on a basement membrane matrix. However, the basement membrane-promoted persistence of cytokeratin synthesis is not accompanied by expression of cytokeratin G (no. 19), the major acidic cytokeratin of mesothelium in vivo. While cells grown on plastic establish a prominent juxtanuclear assemblage of tonofilaments, those cultured on basement membrane exhibit cytokeratin filaments which are distributed throughout the cytoplasm and attach to neighboring cells at the plasma membrane. This latter pattern resembles that seen in the intact mesothelium. Intermediate filaments are markers of cellular differentiation, but their roles are obscure. The response of cultured mesothelial cells to different growth substrata supports the hypothesis that intermediate filament synthesis is influenced by cellular contact with the extracellular matrix.

scholarly journals Substrate stiffness regulates solubility of cellular vimentin

2014 ◽  
Vol 25 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Maria E. Murray ◽  
Melissa G. Mendez ◽  
Paul A. Janmey
Keyword(s):  
Unit Length ◽  
Substrate Stiffness ◽  
Cell Behavior ◽  
Serum Starvation ◽  
Intermediate Filament Protein ◽  
Membrane Ruffling ◽  
Microtubule Disruption ◽  
P21 Activated Kinase ◽  
Filament Protein

The intermediate filament protein vimentin is involved in the regulation of cell behavior, morphology, and mechanical properties. Previous studies using cells cultured on glass or plastic substrates showed that vimentin is largely insoluble. Although substrate stiffness was shown to alter many aspects of cell behavior, changes in vimentin organization were not reported. Our results show for the first time that mesenchymal stem cells (hMSCs), endothelial cells, and fibroblasts cultured on different-stiffness substrates exhibit biphasic changes in vimentin detergent solubility, which increases from nearly 0 to 67% in hMSCs coincident with increases in cell spreading and membrane ruffling. When imaged, the detergent-soluble vimentin appears to consist of small fragments the length of one or several unit-length filaments. Vimentin detergent solubility decreases when these cells are subjected to serum starvation, allowed to form cell–cell contacts, after microtubule disruption, or inhibition of Rac1, Rho-activated kinase, or p21-activated kinase. Inhibiting myosin or actin assembly increases vimentin solubility on rigid substrates. These data suggest that in the mechanical environment in vivo, vimentin is more dynamic than previously reported and its assembly state is sensitive to stimuli that alter cellular tension and morphology.

scholarly journals Keratin 7 Is a Constituent of the Keratin Network in Mouse Pancreatic Islets and Is Upregulated in Experimental Diabetes

2021 ◽  
Vol 22 (15) ◽  
pp. 7784
Author(s):  
Catharina M. Alam ◽  
Sarah Baghestani ◽  
Ada Pajari ◽  
M. Bishr Omary ◽  
Diana M. Toivola
Keyword(s):  
Experimental Diabetes ◽  
Streptozotocin Diabetes ◽  
Intermediate Filament Protein ◽  
Β Cells ◽  
Diabetes Model ◽  
Cytoplasmic Filaments ◽  
Mouse Pancreatic Islets ◽  
Filament Networks ◽  
Filament Protein ◽  
Keratin 7

Keratin (K) 7 is an intermediate filament protein expressed in ducts and glands of simple epithelial organs and in urothelial tissues. In the pancreas, K7 is expressed in exocrine ducts, and apico-laterally in acinar cells. Here, we report K7 expression with K8 and K18 in the endocrine islets of Langerhans in mice. K7 filament formation in islet and MIN6 β-cells is dependent on the presence and levels of K18. K18-knockout (K18‒/‒) mice have undetectable islet K7 and K8 proteins, while K7 and K18 are downregulated in K8‒/‒ islets. K7, akin to F-actin, is concentrated at the apical vertex of β-cells in wild-type mice and along the lateral membrane, in addition to forming a fine cytoplasmic network. In K8‒/‒ β-cells, apical K7 remains, but lateral keratin bundles are displaced and cytoplasmic filaments are scarce. Islet K7, rather than K8, is increased in K18 over-expressing mice and the K18-R90C mutation disrupts K7 filaments in mouse β-cells and in MIN6 cells. Notably, islet K7 filament networks significantly increase and expand in the perinuclear regions when examined in the streptozotocin diabetes model. Hence, K7 represents a significant component of the murine islet keratin network and becomes markedly upregulated during experimental diabetes.

Immunocytochemical localization of desmin and vimentin in chick embryonic myocardial cells

1990 ◽  
Vol 48 (3) ◽  
pp. 448-449
Author(s):  
Yukiko Sugi
Keyword(s):  
Sodium Methoxide ◽  
Intermediate Filament Protein ◽  
Chick Embryos ◽  
Immunocytochemical Localization ◽  
Myocardial Cells ◽  
Immunofluorescence Study ◽  
Immunofluorescent Localization ◽  
Rabbit Igg ◽  
Semithin Sections ◽  
Filament Protein

In cultured skeletal muscle cells of chick, one intermediate filament protein, vimentin, is primarily formed and then synthesis of desmin follows. Coexistence of vimentin and desmin has been immunocytochemically confirmed in chick embryonic skeletal musclecells. Immunofluorescent localization of vimentin and desmin has been described in developing myocardial cells of hamster. However, initial localization of desmin and vimentin in early embryonic heart has not been reported in detail. By quick-freeze deep-etch method a loose network of intermediate filaments was revealed to exist surrounding myofibrils. In this report, immunocytochemical localization of desmin and vimentin is visualized in early stages of chick embryonic my ocardium.Chick embryos, Hamburger-Hamilton (H-H) stage 8 to hatch, and 1 day old postnatal chicks were used in this study. For immunofluorescence study, each embryo was fixed with 4% paraformaldehyde and embedded in Epon 812. De-epoxinized with sodium methoxide, semithin sections were stained with primary antibodies (rabbit anti-desmin antibody and anti-vimentin antibody)and secondary antibody (RITC conjugated goat-anti rabbit IgG).

Sign in / Sign up

Export Citation Format

Share Document