Rheology and Microrheology of Semiflexible Polymer Solutions:  Actin Filament Networks

1998 ◽  
Vol 31 (19) ◽  
pp. 6486-6492 ◽  
Author(s):  
Jingyuan Xu ◽  
Andre Palmer ◽  
Denis Wirtz
Keyword(s):  
Actin Filament ◽  
Polymer Solutions ◽  
Semiflexible Polymer ◽  
Filament Networks

scholarly journals A novel role for WAVE1 in controlling actin network growth rate and architecture

2015 ◽  
Vol 26 (3) ◽  
pp. 495-505 ◽  
Author(s):  
Meredith O. Sweeney ◽  
Agnieszka Collins ◽  
Shae B. Padrick ◽  
Bruce L. Goode
Keyword(s):  
Actin Filament ◽  
Specific Activity ◽  
Inhibitory Effect ◽  
Actin Network ◽  
Inhibitory Effects ◽  
Cellular Functions ◽  
Network Growth ◽  
Assembly Kinetics ◽  
Filament Networks ◽  
First Time

Branched actin filament networks in cells are assembled through the combined activities of Arp2/3 complex and different WASP/WAVE proteins. Here we used TIRF and electron microscopy to directly compare for the first time the assembly kinetics and architectures of actin filament networks produced by Arp2/3 complex and dimerized VCA regions of WAVE1, WAVE2, or N-WASP. WAVE1 produced strikingly different networks from WAVE2 or N-WASP, which comprised unexpectedly short filaments. Further analysis showed that the WAVE1-specific activity stemmed from an inhibitory effect on filament elongation both in the presence and absence of Arp2/3 complex, which was observed even at low stoichiometries of WAVE1 to actin monomers, precluding an effect from monomer sequestration. Using a series of VCA chimeras, we mapped the elongation inhibitory effects of WAVE1 to its WH2 (“V”) domain. Further, mutating a single conserved lysine residue potently disrupted WAVE1's inhibitory effects. Taken together, our results show that WAVE1 has unique activities independent of Arp2/3 complex that can govern both the growth rates and architectures of actin filament networks. Such activities may underlie previously observed differences between the cellular functions of WAVE1 and WAVE2.

scholarly journals Cortical filamentous actin disassembly and scinderin redistribution during chromaffin cell stimulation precede exocytosis, a phenomenon not exhibited by gelsolin.

1991 ◽  
Vol 113 (5) ◽  
pp. 1057-1067 ◽  
Author(s):  
M L Vitale ◽  
A Rodríguez Del Castillo ◽  
L Tchakarov ◽  
J M Trifaró
Keyword(s):  
Actin Filament ◽  
Chromaffin Cells ◽  
Chromaffin Cell ◽  
Catecholamine Secretion ◽  
Cortical Region ◽  
Cortical Surface ◽  
Filamentous Actin ◽  
Cell Stimulation ◽  
Rhodamine Phalloidin ◽  
Filament Networks

Immunofluorescence and cytochemical studies have demonstrated that filamentous actin is mainly localized in the cortical surface of the chromaffin cell. It has been suggested that these actin filament networks act as a barrier to the secretory granules, impeding their contact with the plasma membrane. Stimulation of chromaffin cells produces a disassembly of actin filament networks, implying the removal of the barrier. The presence of gelsolin and scinderin, two Ca(2+)-dependent actin filament severing proteins, in the cortical surface of the chromaffin cells, suggests the possibility that cell stimulation brings about activation of one or more actin filament severing proteins with the consequent disruption of actin networks. Therefore, biochemical studies and fluorescence microscopy experiments with scinderin and gelsolin antibodies and rhodamine-phalloidin, a probe for filamentous actin, were performed in cultured chromaffin cells to study the distribution of scinderin, gelsolin, and filamentous actin during cell stimulation and to correlate the possible changes with catecholamine secretion. Here we report that during nicotinic stimulation or K(+)-evoked depolarization, subcortical scinderin but not gelsolin is redistributed and that this redistribution precedes catecholamine secretion. The rearrangement of scinderin in patches is mediated by nicotinic receptors. Cell stimulation produces similar patterns of distribution of scinderin and filamentous actin. However, after the removal of the stimulus, the recovery of scinderin cortical pattern of distribution is faster than F-actin reassembly, suggesting that scinderin is bound in the cortical region of the cell to a component other than F-actin. We also demonstrate that peripheral actin filament disassembly and subplasmalemmal scinderin redistribution are calcium-dependent events. Moreover, experiments with an antibody against dopamine-beta-hydroxylase suggest that exocytosis sites are preferentially localized to areas of F-actin disassembly.

scholarly journals Semiflexible polymer solutions. I. Phase behavior and single-chain statistics

2003 ◽  
Vol 119 (24) ◽  
pp. 13113-13128 ◽  
Author(s):  
Andrew J. Spakowitz ◽  
Zhen-Gang Wang
Keyword(s):  
Phase Behavior ◽  
Polymer Solutions ◽  
Single Chain ◽  
Semiflexible Polymer

Interactions between Surfaces in Polydisperse Semiflexible Polymer Solutions

2009 ◽  
Vol 42 (19) ◽  
pp. 7563-7570 ◽  
Author(s):  
Clifford E. Woodward ◽  
Jan Forsman
Keyword(s):  
Polymer Solutions ◽  
Semiflexible Polymer

scholarly journals Abp1p and cortactin, new “hand-holds” for actin

2001 ◽  
Vol 154 (4) ◽  
pp. 679-682 ◽  
Author(s):  
Isabel M. Olazabal ◽  
Laura M. Machesky
Keyword(s):  
Complex Networks ◽  
Actin Filament ◽  
Yeast Protein ◽  
Filament Networks ◽  
Shed Light ◽  
The Way

Recently, two new ligands of the Arp2/3 complex have been described that may shed light on the way cells organize complex networks of actin in response to signals. Abp1p, a yeast protein involved in endocytosis, and cortactin, a mammalian src substrate, both enhance the ability of the Arp2/3 complex to assemble branched actin filament networks.

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