Journal ArticleDOI
Septins promote F-actin ring formation by crosslinking actin filaments into curved bundles
Manos Mavrakis,Y. Azou-Gros,Fc Tsai,José Alvarado,Aurélie Bertin,Alla Kress,Sophie Brasselet,Gijsje H. Koenderink,Thomas Lecuit +8 more
TLDR
In vitro reconstitution assays show that septins alone bundle actin filaments into rings, accounting for the defects in actin ring formation in septin mutants, and highlight unique functions of septin in the organization of contractile actomyosin rings.Abstract:
Animal cell cytokinesis requires a contractile ring of crosslinked actin filaments and myosin motors. How contractile rings form and are stabilized in dividing cells remains unclear. We address this problem by focusing on septins, highly conserved proteins in eukaryotes whose precise contribution to cytokinesis remains elusive. We use the cleavage of the Drosophila melanogaster embryo as a model system, where contractile actin rings drive constriction of invaginating membranes to produce an epithelium in a manner akin to cell division. In vivo functional studies show that septins are required for generating curved and tightly packed actin filament networks. In vitro reconstitution assays show that septins alone bundle actin filaments into rings, accounting for the defects in actin ring formation in septin mutants. The bundling and bending activities are conserved for human septins, and highlight unique functions of septins in the organization of contractile actomyosin rings.read more
Citations
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Journal ArticleDOI
Extended-resolution structured illumination imaging of endocytic and cytoskeletal dynamics
Dong Li,Lin Shao,Bi-Chang Chen,Xi Zhang,Xi Zhang,Mingshu Zhang,Brian Moses,Daniel E. Milkie,Jordan R. Beach,John A. Hammer,Mithun Pasham,Tomas Kirchhausen,Michelle A. Baird,Michelle A. Baird,Michael W. Davidson,Pingyong Xu,Eric Betzig +16 more
TL;DR: Two approaches are used to improve the resolution of SIM to allow live cell imaging of dynamic cellular processes, including endocytosis and cytoskeleton remodeling, and it is demonstrated that the resolution for these methods is comparable with or better than other SR approaches yet allowed us to image at far higher speeds, and for far longer durations.
Journal ArticleDOI
Cytokinetic Abscission: Molecular Mechanisms and Temporal Control
Beata Mierzwa,Daniel W. Gerlich +1 more
TL;DR: A brief overview of early cytokinesis events in animal cells is provided and in depth recently emerging models for the assembly and function of the abscission machinery and its temporal coordination with chromosome segregation are covered.
Journal ArticleDOI
Micron-scale plasma membrane curvature is recognized by the septin cytoskeleton
Andrew A. Bridges,Andrew A. Bridges,Maximilian S. Jentzsch,Patrick W. Oakes,Patricia Occhipinti,Amy S. Gladfelter,Amy S. Gladfelter +6 more
TL;DR: Fungal and human septins can distinguish between different degrees of micron-scale curvature in cells, suggesting that this property of the septin cytoskeleton provides a cell with a mechanism to sense its local shape.
Journal ArticleDOI
Cytoskeletal dynamics: a view from the membrane.
TL;DR: These studies highlight the membrane’s central role in coordinating these cytoskeletal systems to carry out essential processes, such as endocytosis, spindle positioning, and cellular compartmentalization.
Journal ArticleDOI
Quantitative nanoscale imaging of orientational order in biological filaments by polarized superresolution microscopy
Cesar Augusto Valades Cruz,Haitham A. Shaban,Alla Kress,Nicolas Bertaux,Serge Monneret,Manos Mavrakis,Julien Savatier,Sophie Brasselet +7 more
TL;DR: It is demonstrated that quantitative single-molecule polarized detection in biological filament assemblies allows not only to correct for the rotational flexibility of the label but also to image orientational order of filaments at the nanoscale using superresolution capabilities.
References
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TL;DR: This chapter presents several techniques for further purification of the actin, finding that extensive dialysis results in eventual dissociation of actin-myosin complexes and appearance of myosin in the final product.
Journal ArticleDOI
The Molecular Requirements for Cytokinesis
TL;DR: After anaphase onset, animal cells build an actomyosin contractile ring that constricts the plasma membrane to generate two daughter cells connected by a cytoplasmic bridge, which is ultimately severed to complete cytokinesis.
Journal ArticleDOI
Planar polarized actomyosin contractile flows control epithelial junction remodelling
TL;DR: This work investigates how cell deformations emerge from the interplay between force generation and cortical force transmission during this remodelling in Drosophila melanogaster and suggests that the medial flow pattern reflects equilibrium properties of force transmission and coupling to E-cadherin by α-Catenin.
Journal ArticleDOI
Septins: the fourth component of the cytoskeleton
TL;DR: Investigations on the molecular functions of septins have highlighted their roles as scaffolds for protein recruitment and as diffusion barriers for subcellular compartmentalization in numerous biological processes, including cell division and host–microorganism interactions.