Unconventional Salt Trend from Soft to Stiff in Single Neurofilament Biopolymers

Beck, Roy; Deek, Joanna; Choi, Myung Chul; Ikawa, Taiji; Watanabe, Osamu; Frey, Erwin; Pincus, P.; Safinya, Cyrus R.

doi:10.1021/la103655x

Cited by 42 publications

(54 citation statements)

References 41 publications

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“…The main difference between native NFs (with contour length on the order of a few microns 10 ) and reconstituted NFs is that the latter have a shorter contour length of E200 nm (ref. 37). Thus, although the single-molecule properties between NFs with small and long contour lengths will be different, we expect that the shorter contour length should not lead to significantly different properties (both microscopic and macroscopic) of the extended NF network hydrogels compared to networks consisting of longer native filaments.…”

Section: Methodsmentioning

confidence: 90%

Neurofilament sidearms modulate parallel and crossed-filament orientations inducing nematic to isotropic and re-entrant birefringent hydrogels

et al. 2013

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Neurofilaments are intermediate filaments assembled from the subunits neurofilament-low, neurofilament-medium and neurofilament-high. In axons, parallel neurofilaments form a nematic liquid-crystal hydrogel with network structure arising from interactions between the neurofilaments' C-terminal sidearms. Here we report, using small-angle X-ray-scattering, polarized-microscopy and rheometry, that with decreasing ionic strength, neurofilament-lowhigh, neurofilament-low-medium and neurofilament-low-medium-high hydrogels transition from the nematic hydrogel to an isotropic hydrogel (with random, crossed-filament orientation) and to an unexpected new re-entrant liquid-crystal hydrogel with parallel filaments-the bluish-opaque hydrogel-with notable mechanical and water retention properties reminiscent of crosslinked hydrogels. Significantly, the isotropic gel phase stability is sidearm-dependent: neurofilament-low-high hydrogels exhibit a wide ionic strength range, neurofilament-low-medium hydrogels a narrow ionic strength range, whereas neurofilamentlow hydrogels lack the isotropic gel phase. This suggests a dominant regulatory role for neurofilament-high sidearms in filament reorientation plasticity, facilitating organelle transport in axons. Neurofilament-inspired biomimetic hydrogels should therefore exhibit remarkable structure-dependent moduli and slow and fast water-release properties.

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Section: Methodsmentioning

confidence: 90%

Neurofilament sidearms modulate parallel and crossed-filament orientations inducing nematic to isotropic and re-entrant birefringent hydrogels

et al. 2013

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“…This review describes experiments on reconstituted NF hydrogels, including studies in which the subunit compositions are near those found in axons and dendrites in vivo (9,(28)(29)(30)(31)(32). The ability to reconstitute NF hydrogels at different subunit compositions is essential, and together with small-angle-X-ray scattering (SAXS) and SAXS osmotic pressure techniques, allows clarification of the role of each subunit on hydrogel structure and phase behavior (which includes NF orientational flexibility) as well as on the interfilament forces related to the mechanical properties of the network (33)(34)(35)(36).…”

Section: Introductionmentioning

confidence: 99%

Assembly of Biological Nanostructures: Isotropic and Liquid Crystalline Phases of Neurofilament Hydrogels

Safinya

Deek

Beck

et al. 2015

Annu. Rev. Condens. Matter Phys.

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Neurofilaments are the building blocks of the major cytoskeletal network found in the axons of vertebrate neurons. The filaments consist of three distinct molecularweight subunits-neurofilament-low, neurofilament-medium, and neurofilamenthigh-which coassemble into 10-nm flexible rods with protruding intrinsically disordered C-terminal sidearms that mediate interfilament interactions and hydrogel formation. Molecular neuroscience research includes areas focused on elucidating the functions of each subunit in network formation, during which disruptions are a hallmark of motor-neuron diseases. Here, modern concepts and methods from soft condensed matter physics are combined to address the role of subunits as it relates to interfilament forces and phase behavior in neurofilament networks. Significantly, the phase behavior studies reveal that although neurofilamentmedium subunits promote nematic liquid crystal hydrogel phase stability with parallel filament orientation, neurofilament-high subunits stabilize the hydrogel in the nematic phase close to the isotropic gel phase with random, crossed-filament orientation. This indicates a regulatory role for neurofilament-high subunits in filament orientational plasticity required for organelle (e.g., membrane-bound vesicle or mitochondrion) transport along microtubules embedded in neurofilament hydrogels. Future studies-for example, on neurofilament subunits mixed with tubulin and microtubule-associated proteins-should lead to a deeper understanding of forces and heterogeneous structures in neuronal cytoskeletons. 6.1Review in Advance first posted online on January 2, 2015. (Changes may still occur before final publication online and in print.)Changes may still occur before final publication online and in print Annu. Rev. Condens. Matter Phys. 2015.6. Downloaded from www.annualreviews.org Access provided by Selcuk University on 01/05/15. For personal use only.

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“…It has been recognized for some time that the cytoskel-41 eton, a composite network of filamentous proteins, along with corre- 42 sponding linker proteins and molecular motors is a highly mobile, 43 viscoelastic and flexible entity, which determines cell mechanics to a 44 great extent [1]. Actin-based microfilaments (MFs) and tubulin-based 45 microtubules (MTs) are polar filaments and both interact directly with 46 the molecular motors myosin or kinesin and dynein, respectively.…”

mentioning

confidence: 99%

Physical properties of cytoplasmic intermediate filaments

Block

Schroeder

Pawelzyk

et al. 2015

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

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Intermediate filaments (IFs) constitute a sophisticated filament system in the cytoplasm of eukaryotes. They form bundles and networks with adapted viscoelastic properties and are strongly interconnected with the other filament types, microfilaments and microtubules. IFs are cell type specific and apart from biochemical functions, they act as mechanical entities to provide stability and resilience to cells and tissues. We review the physical properties of these abundant structural proteins including both in vitro studies and cell experiments. IFs are hierarchical structures and their physical properties seem to a large part be encoded in the very specific architecture of the biopolymers. Thus, we begin our review by presenting the assembly mechanism, followed by the mechanical properties of individual filaments, network and structure formation due to electrostatic interactions, and eventually the mechanics of in vitro and cellular networks. This article is part of a Special Issue entitled: Mechanobiology.

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Unconventional Salt Trend from Soft to Stiff in Single Neurofilament Biopolymers

Cited by 42 publications

References 41 publications

Neurofilament sidearms modulate parallel and crossed-filament orientations inducing nematic to isotropic and re-entrant birefringent hydrogels

Neurofilament sidearms modulate parallel and crossed-filament orientations inducing nematic to isotropic and re-entrant birefringent hydrogels

Assembly of Biological Nanostructures: Isotropic and Liquid Crystalline Phases of Neurofilament Hydrogels

Physical properties of cytoplasmic intermediate filaments

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