Network filaments

Forgacs G 1995 On the possible role of cytoskeletal filamentous networks in intracellular signalling J. Ceii. Sc/. 108 2131-43... 

Two cytoskeletal proteins, tltln (also known as connectm) and nebulm, account for 15% of the total protein in the myofibril. Together these proteins form a flexible filamentous network that surrounds the myofibrils. Titin is an elastic protein and can stretch under tension. Its discovery and characteriza-... 

Desmoplakin is the most abundant desmosomal component that plays a critical role in linking intermediate filament networks to the desmosomal plaque. Desmoplakin forms rod-like dimers that bind to intermediate filaments and to the cadherin-associated proteins plakoglobin and plakophilin. Gene knock-out experiments have revealed an essential role of desmoplakin in establishing cell-cell contacts in early mouse embryos. 

Fig.1 The chitin-secreting gland of the marine worm Riftia pachyptila. Part 1 the central lumen (7, upper-right corner) contains the amorphous chitin secretion (c) the suh-lumen marked with an arrow is emptying its content in the central lumen. Part 2 chitin mi-crofihrils sections (c) the filamentous network (arrows) that connects the edges of the crystallite sections, seems to contain protein (From ShUlito et al., in Chitin Enzymology, Vol. 1, R.A.A. Muzzarelli (ed.) pp. 129-136, Atec, Italy, 1993)...

Vikstrom, K.L., Borisy, G.G., Goldman, R.D. (1989). Dynamic aspects of intermediate filament networks in BHK-21 cells. Proc. Natl. Acad. Sci. USA 86, 549-553. 

Fig. 8 Cryo-TEM image of aqueous PB-P2VPQ micelles showing filament network of polyelectrolyte chain bundles. Scale bar is 50 nm. Reprinted with permission from [15]. Copyright (2004) Springer...

The above processes describe how the growth and depolymerisation of actin filaments thin filaments) is controlled. However, actin filaments are assembled into filamentous networks, and these three-dimensional structures are themselves controlled and also stabilised by a number of proteins ... 

Assembly of the actin network merely by interaction with these binding proteins can itself account for pseudopodia formation and propulsive movement. However, there is some evidence to suggest that F-actin-myosin interactions are required for vectorial movement hence it has been demonstrated that pseudopodia contain filament networks comprising actin and myosin. Myosin plays a role in the contractile movement of neutrophils in a... 

Oster (1984) and colleagues have proposed the following model. The actin-filament network is a net negatively-charged, cross-linked (with filamin) polymer network, contained within an ionic aqueous environment This may thus be considered as a charged polymer trapped within a semi-... 

If the cross-links or polymers are severed, then some elastic energy is released and the system will adopt a new (larger) equilibrium volume where greater distortion is conferred upon a meshwork that has fewer cross-links. Thus, upon increases in Ca2+, gelsolin activity leads to an increase in the volume of the actin-filament network. The additional influence of myosin on such a meshwork is similar to that proposed in the Stossel model. Thus, three-dimensional Ca2+ gradients (between a localised region of the cell surface and an external structure) can result in complex shape changes. 

Sheterline, P., Rickard, J. E. (1989). The cortical actin filament network of neutrophil leucocytes during phagocytosis and chemotaxis. In The Neutrophil Cellular Biochemistry and Physiology (Hallett, M. B., ed.), pp. 141-65, CRC Press, Boca Raton, Fla. 

Another example of how whole-mount technology has facilitated the study of three-dimensional arrays of filamentous networks is the visualization of cytoskeletal elements within the context of tissues. It is only through whole-... 

The mechanical properties of actin filament networks depend on the manner in which actin monomer is prepared and stored, as well as how they are polymerized conditions. Differences in mechanical properties are not the consequence of using two different types of forced oscillatory rheometers. Xu et aid found that filaments assembled in EGTA and Mg from fresh, gel-filtered ATP-actin monomer (1 mg/mL) have an elastic storage... 

Dolastatin 10 has been evaluated with promising results in a phase I clinical study in patients with solid tumors. Subsequently, its noticeable antitumor activity was well documented in various in vitro and in vivo tumor models (Madden et al., 2000). More than a dozen dolastatin peptides have been isolated to date. Recent studies have shown, for example, that the depsipeptide dolastatin 11 arrests cells at cytokinesis by causing a rapid and massive rearrangement of the cellular actin filament network and induces the hyperpolymerization of purified actin (Bai et al., 2001). The effects of dolastatin 11 were similar to those of the sponge-derived depsipeptide jasplakinolide however, dolastatin 11 exhibited threefold more cytotoxicity than jasplakinolide in the cells studied. 

Figure 2.1 Scanning electron micrographs of Fe -induced cold-set gels of P-lactoglobulin filamentous gel (top) and particulate gel (bottom). The gel microstructure depends on the iron/protein ratio. At low iron/protein ratios, a homogeneous filamentous network is obtained, whereas at high iron/protein ratios an aggregated particle gel is produced. Reproduced from Chen et al (2006a) with permission.

Dale, B. A., Presland, R. B., Lewis, S. P., Underwood, R. A., and Fleckman, P. (1997). Transient expression of epidermal filaggrin in cultured cells causes collapse of intermediate filament networks with alteration of cell shape and nuclear integrity. J. Invest. Dermatol. 108, 179—187. 

Helfand, B. T., Mikami, A., Vallee, R. B., and Goldman, R. D. (2002). A requirement for cytoplasmic dynein and dynactin in intermediate filament network assembly and organization. /. Cell Biol. 157, 795—806. 

Stappenbeck, T. S., Bornslaeger, E. A., Corcoran, C. M., Luu, H. H., Virata, M. L. A., and Green, K.J. (1993). Functional analysis of desmoplakin domains Specification of the interaction with keratin versus vimentin intermediate filament networks. / Biol. Chem. 123, 691—705. 

Fig. 10 Cryo-TEM images of polyelectrolyte block copolymer micelles (PB-P2VPMeI) with unperturbed spherical corona (a), corona filaments (b), filament networks (c), and micellar strings. The scale bar is 50 nm [56]...

Fig. 11 Schematic view of a possible mechanism for the formation of micellar and filament networks. Different states of association are shown as function of intermicellar distance r...

The formation of filaments, filament networks, and micellar strings is schematically shown in Fig. 11 as a function of the intermicellar distance r. Upon collisions small repulsive interactions are overcome to overlap adjacent micellar shells to form a shared ion cloud. The disruption of strings leads to the formation of filaments which can lead to a filament network. Further increase of intermicellar distance disrupts filament connections to form single micelles. 

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