scholarly journals Tuning intermediate filament mechanics by variation of pH and ion charges

Nanoscale ◽  
2020 ◽  
Vol 12 (28) ◽  
pp. 15236-15245 ◽  
Author(s):  
Anna V. Schepers ◽  
Charlotta Lorenz ◽  
Sarah Köster
Keyword(s):  
Mechanical Properties ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Ion Concentration

The mechanical properties of intermediate filaments depend on pH and ion concentration, providing cells with tools to tune their mechanics.

scholarly journals Tuning Intermediate Filament Mechanics by Variation of pH and Ion Charges

2019 ◽  
Author(s):  
Anna V. Schepers ◽  
Charlotta Lorenz ◽  
Sarah Köster
Keyword(s):  
Mechanical Properties ◽  
Monte Carlo ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Actin Filaments ◽  
Electrostatic Interactions ◽  
Ion Concentration ◽  
Ion Concentrations ◽  
Ph Values ◽  
Internal Forces

The cytoskeleton is formed by three types of filamentous proteins – microtubules, actin filaments, and intermediate filaments (IFs) – and enables cells to withstand external and internal forces. Vimentin is the most abundant IF protein in humans and assembles into 10 nm diameter filaments with remarkable mechanical properties, such as high extensibility and stability. It is, however, unclear to which extent these properties are influenced by the electrostatic environment. Here, we study the mechanical properties of single vimentin filaments by employing optical trapping combined with microfluidics. Force-strain curves, recorded at varying ion concentrations and pH values, reveal that the mechanical properties of single vimentin IFs are influenced by pH and ion concentration. By combination with Monte Carlo simulations, we relate these altered mechanics to electrostatic interactions of subunits within the filaments. We thus suggest possible mechanisms that allow cells to locally tune their stiffness without remodeling the entire cytoskeleton.

Intermediate Filament Cytoskeletal System: Dynamic and Mechanical Properties

1998 ◽  
Vol 194 (3) ◽  
pp. 361-363 ◽  
Author(s):  
R. D. Goldman ◽  
S. Clement ◽  
S. Khuon ◽  
R. Moir ◽  
A. Trejo-Skalli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intermediate Filament ◽  
System Dynamic ◽  
Cytoskeletal System

scholarly journals Effects of mechanical tension on protrusive activity and microfilament and intermediate filament organization in an epidermal epithelium moving in culture.

1986 ◽  
Vol 102 (4) ◽  
pp. 1400-1411 ◽  
Author(s):  
J Kolega
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Mechanical Tension ◽  
Cytoskeletal Organization ◽  
Structural Support ◽  
Transmission Electron ◽  
Locomotive Activity ◽  
Filament Surface

Mechanical tension influences tissue morphogenesis and the synthetic, mitotic, and motile behavior of cells. To determine the effects of tension on epithelial motility and cytoskeletal organization, small, motile clusters of epidermal cells were artificially extended with a micromanipulated needle. Protrusive activity perpendicular to the axis of tension was dramatically suppressed. To determine the ultrastructural basis for this phenomenon, cells whose exact locomotive behavior was recorded cinemicrographically were examined by transmission electron microscopy. In untensed, forward-moving lamellar protrusions, microfilaments appear disorganized and anisotropically oriented. But in cytoplasm held under tension by micromanipulation or by the locomotive activity of other cells within the epithelium, microfilaments are aligned parallel to the tension. In non-spreading regions of the epithelial margin, microfilaments lie in tight bundles parallel to apparent lines of tension. Thus, it appears that tension causes alignment of microfilaments. In contrast, intermediate filaments are excluded from motile protrusions, being confined to the thicker, more central part of the cell. They roughly follow the contours of the cell, but are not aligned relative to tension even when microfilaments in the same cell are. This suggests that the organization of intermediate filaments is relatively resistant to physical distortion and the intermediate filaments may act as passive structural support within the cell. The alignment of microfilaments under tension suggests a mechanism by which tension suppresses protrusive activity: microfilaments aligned by forces exerted through filament-surface or filament-filament interconnections cannot reorient against such force and so cannot easily extend protrusions in directions not parallel to tension.

Novel features of intermediate filament dynamics revealed by green fluorescent protein chimeras

1998 ◽  
Vol 111 (13) ◽  
pp. 1767-1778 ◽  
Author(s):  
C.L. Ho ◽  
J.L. Martys ◽  
A. Mikhailov ◽  
G.G. Gundersen ◽  
R.K. Liem
Keyword(s):  
Green Fluorescent Protein ◽  
Dynamic Behavior ◽  
Cell Lines ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Fluorescent Protein ◽  
Nih3t3 Cells ◽  
Green Fluorescent ◽  
Filament Network ◽  
Perinuclear Area

In order to study the dynamic behavior of intermediate filament networks in living cells, we have prepared constructs fusing green fluorescent protein to intermediate filament proteins. Vimentin fused to green fluorescent protein labeled the endogenous intermediate filament network. We generated stable SW13 and NIH3T3 cell lines that express an enhanced green fluorescent protein fused to the N-terminus of full-length vimentin. We were able to observe the dynamic behavior of the intermediate filament network in these cells for periods as long as 4 hours (images acquired every 2 minutes). In both cell lines, the vimentin network constantly moves in a wavy manner. In the NIH3T3 cells, we observed extension of individual vimentin filaments at the edge of the cell. This movement is dependent on microtubules, since the addition of nocodazole stopped the extension of the intermediate filaments. Injection of anti-IFA causes the redistribution or ‘collapse’ of intermediate filaments. We injected anti-IFA antibodies into NIH3T3 cells stably expressing green fluorescent protein fused to vimentin and found that individual intermediate filaments move slowly towards the perinuclear area without obvious disassembly. These results demonstrate that individual intermediate filaments are translocated during the collapse, rather than undergoing disassembly-induced redistribution. Injections of tubulin antibodies disrupt the interactions between intermediate filaments and stable microtubules and cause the collapse of the vimentin network showing that these interactions play an important role in keeping the intermediate filament network extended. The nocodazole inhibition of intermediate filament extension and the anti-IFA microinjection experiments are consistent with a model in which intermediate filaments exhibit an extended distribution when tethered to microtubules, but are translocated to the perinuclear area when these connections are severed.

scholarly journals Glial Fibrillary Acidic Protein (GFAP) in Oligodendrogliomas: A Reflection of Transient GFAP Expression by Immature Oligodendroglia

1986 ◽  
Vol 13 (4) ◽  
pp. 307-311 ◽  
Author(s):  
V. Jagadha ◽  
W.C. Halliday ◽  
L.E. Becker
Keyword(s):  
White Matter ◽  
Glial Fibrillary Acidic Protein ◽  
Tumor Cells ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Immunohistochemical Staining ◽  
Neuron Specific Enolase ◽  
Acidic Protein ◽  
Gfap Expression ◽  
S 100

ABSTRACT:Fourteen pure oligodendrogliomas were studied by light- and electronmicroscopy and immunohistochemistry to examine glial fibrillary acidic protein (GFAP) positivity in the tumors. To compare the immunohistochemical staining patterns of neoplastic oligodendroglia and immature oligodendroglia, myelination glia in the white matter of eight normal brains from children under 6 months of age were studied. The tumors possessed light microscopic and ultrastructural features characteristic of oligodendrogliomas. Microtubules were found in the cytoplasm of nine tumors on electronmicroscopy. In one, intermediate filaments and microtubules were observed in occasional tumor cells with polygonal crystalline structures in the cytoplasm. Using the peroxidase-antiperoxidase technique, all specimens were stained for GFAP, vimentin, S-100 and neuron-specific enolase (NSE). In nine tumors, variable numbers of cells with an oligodendroglial morphology reacted positively for GFAP. All tumors were positive for S-100 and negative for vimentin and NSE. The myelination glia in the eight normal brains stained positively for GFAP but not for vimentin. Vimentin is expressed by developing, reactive and neoplastic astrocytes. Thus, GFAP positivity combined with vimentin negativity in both neoplastic and immature oligodendroglia suggests that GFAP positivity in oligodendrogliomas may reflect the transient expression of this intermediate filament by immature oligodendroglia.

scholarly journals The Mechanical Properties of Hydrated Intermediate Filaments: Insights from Hagfish Slime Threads

2003 ◽  
Vol 85 (3) ◽  
pp. 2015-2027 ◽  
Author(s):  
Douglas S. Fudge ◽  
Kenn H. Gardner ◽  
V. Trevor Forsyth ◽  
Christian Riekel ◽  
John M. Gosline
Keyword(s):  
Mechanical Properties ◽  
Intermediate Filaments

Interactions between peripherin and neurofilaments in cultured cells: disruption of peripherin assembly by the NF-M and NF-H subunits

1999 ◽  
Vol 77 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Jean-Martin Beaulieu ◽  
Janice Robertson ◽  
Jean-Pierre Julien
Keyword(s):  
Nervous System ◽  
Peripheral Nervous System ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Cultured Cells ◽  
Intermediate Filament Protein ◽  
Physiological Conditions ◽  
Filament Protein ◽  
Filament Network ◽  
Filament Type

Neurofilaments are the principal intermediate filament type expressed by neurons. They are formed by the co-assembly of three subunits: NF-L, NF-M, and NF-H. Peripherin is another intermediate filament protein expressed mostly in neurons of the peripheral nervous system. In contrast to neurofilaments, peripherin can self-assemble to establish an intermediate filament network in cultured cells. The co-expression of neurofilaments and peripherin is found mainly during development and regeneration. We used SW13 cells devoid of endogenous cytoplasmic intermediate filaments to assess the exact assembly characteristics of peripherin with each neurofilament subunit. Our results demonstrate that peripherin can assemble with NF-L. In contrast, the co-expression of peripherin with the large neurofilament subunits interferes with peripherin assembly. These results confirm the existence of interactions between peripherin and neurofilaments in physiological conditions. Moreover, they suggest that perturbations in the stoichiometry of neurofilaments can have an impact on peripherin assembly in vivo.Key words: peripherin, neurofilament, SW13 cells, intermediate filament.

scholarly journals Interaction of Theiler’s Virus with Intermediate Filaments of Infected Cells

1998 ◽  
Vol 72 (12) ◽  
pp. 9553-9560 ◽  
Author(s):  
Patrick Nédellec ◽  
Patrick Vicart ◽  
Christine Laurent-Winter ◽  
Cécile Martinat ◽  
Marie-Christine Prévost ◽  
...  
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Close Contact ◽  
Theiler's Virus ◽  
Virus Particles ◽  
Host Cell Proteins ◽  
Encephalomyelitis Virus ◽  
Infected Cells ◽  
Main Components ◽  
Filament Network

ABSTRACT Theiler’s murine encephalomyelitis virus is a neurotropic murine picornavirus which replicates permissively and causes a cytopathic effect in the BHK-21 cell line. We examined the interactions between the GDVII and DA strains of Theiler’s virus and BHK-21 host cell proteins in a virus overlay assay. We observed binding of the virions to two proteins of approximately 60 kDa. These proteins were microsequenced and identified as desmin and vimentin, two main components of the intermediate filament network. The association between desmin or vimentin and virions was demonstrated by immunoprecipitation. Anti-desmin and anti-vimentin monoclonal antibodies precipitated GDVII or DA virions from extracts of infected BHK-21 cells. The intracellular distributions of virions and of the desmin and vimentin intermediate filaments of BHK-21 cells were investigated by two-color immunofluorescence confocal microscopy. Following infection, the intermediate filament network was rearranged into a shell-like structure which surrounded a viral inclusion. Finally, close contact between GDVII virus particles and 10-nm intermediate filaments was observed by electron microscopy.

scholarly journals The focal adhesion scaffold protein Hic-5 regulates vimentin organization in fibroblasts

2019 ◽  
Vol 30 (25) ◽  
pp. 3037-3056 ◽  
Author(s):  
Rishel B. Vohnoutka ◽  
Anushree C. Gulvady ◽  
Gregory Goreczny ◽  
Kyle Alpha ◽  
Samuel K. Handelman ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Actin Cytoskeleton ◽  
Western Blotting ◽  
Focal Adhesion ◽  
Posttranslational Modifications ◽  
Intermediate Filament ◽  
Fluorescence Recovery After Photobleaching ◽  
Scaffold Protein ◽  
Cancer Associated Fibroblasts ◽  
Genetic Ablation

Focal adhesion (FA)-stimulated reorganization of the F-actin cytoskeleton regulates cellular size, shape, and mechanical properties. However, FA cross-talk with the intermediate filament cytoskeleton is poorly understood. Genetic ablation of the FA-associated scaffold protein Hic-5 in mouse cancer-associated fibroblasts (CAFs) promoted a dramatic collapse of the vimentin network, which was rescued following EGFP-Hic-5 expression. Vimentin collapse correlated with a loss of detergent-soluble vimentin filament precursors and decreased vimentin S72/S82 phosphorylation. Additionally, fluorescence recovery after photobleaching analysis indicated impaired vimentin dynamics. Microtubule (MT)-associated EB1 tracking and Western blotting of MT posttranslational modifications indicated no change in MT dynamics that could explain the vimentin collapse. However, pharmacological inhibition of the RhoGTPase Cdc42 in Hic-5 knockout CAFs rescued the vimentin collapse, while pan-formin inhibition with SMIFH2 promoted vimentin collapse in Hic-5 heterozygous CAFs. Our results reveal novel regulation of vimentin organization/dynamics by the FA scaffold protein Hic-5 via modulation of RhoGTPases and downstream formin activity.

THE IDENTIFICATION OF VIMENTIN, AN INTERMEDIATE,FILAMENT SUBUNIT PROTEIN IN HUMAN PLATELETS

1987 ◽  
Author(s):  
L Muszbek ◽  
R Adåny ◽  
M A Glukhova ◽  
M G Frid ◽  
A E Kabakov ◽  
...  
Keyword(s):  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Protein Band ◽  
Human Platelets ◽  
Activation Process ◽  
Structural Reorganization ◽  
Subunit Protein ◽  
Differentiated Cells ◽  
Basic Subunit ◽  
Long Time

In platelets the presence of basic subunit proteins of microtubules as well as microfilaments has been verified a long time ago and it was also shown that both of these cytoskeletal systems go through a tremendous reorganization during the activation process. Surprisingly, none of the components of intermediate filaments has so far been identified in these cells, perhaps because platelets were considered too motile to have intermediate filaments, the most static structures among the three major cytoskeletal systems. By using two different monoclonal antibodies (II C4 and II D8) here we attempted to establish if vimen-tin, an intermediate filament subunit protein present in most differentiating cells, in cells grown in tissue culture and in certain fully differentiated cells also exists in human platelets The IgM type antibodies were characterized by various immuno-morphological and immunobiochemical techniques. They labelled selectively colcemid-sensitive filamentous structures in fibroblasts, in endothelial cells and in vascular but not myometrium smooth muscle and were shown to be monospecific against epitopes on vimentin in fibroblast homogenate. When whole platelet homogenate was submitted to high resolution gradient SDS PAGE and then electroblotted to nitrocellulose sheet, both antibodies reacted with a single protein band of 55 kD that comigrated with fibroblast vimentin. By immunofluorescence microscopy an annular ring-like structure was stained for vimentin that suggests a membran skeletal role for this protein. During pseu-dopode formation a redistribution of vimentin could be observed. Parallel with the disappearance of ring-like structures vimentin appears in pseudopodia suggesting that like in the case of other filamentous systems platelet activation induces a structural reorganization of the intermediate filaments, as well.

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