Transient localized accumulation of actin in Caenorhabditis elegans blastomeres with oriented asymmetric divisions

Development ◽  
1994 ◽  
Vol 120 (8) ◽  
pp. 2317-2328 ◽  
Author(s):  
J.A. Waddle ◽  
J.A. Cooper ◽  
R.H. Waterston
Keyword(s):  
Caenorhabditis Elegans ◽  
Actin Filaments ◽  
Molecular Basis ◽  
Capping Protein ◽  
Daughter Cells ◽  
Microtubule Polymerization ◽  
Microtubule Attachment ◽  
Asymmetric Divisions ◽  
Cytoplasmic Determinants ◽  
Anterior Posterior

During Caenorhabditis elegans embryogenesis, specific cells in the P1 lineage rotate their duplicated centrosome pair onto the anterior-posterior axis; this rotation is correlated with and necessary for a differential inheritance of cytoplasmic determinants in the daughter cells. Centrosome pair rotation is sensitive to inhibitors of actin and microtubule polymerization and may require microtubule attachment to a specific cortical site. We show that actin and the barbed-end binding protein, capping protein, transiently accumulate at this cortical site, possibly by assembly onto persistent remnants of previous cell divisions. Based on these observations, we propose a model for the molecular basis of centrosome rotation that is consistent with the dependence of rotation on actin filaments and microtubules.

Cortical actin movements during the first cell cycle of the Caenorhabditis elegans embryo

1996 ◽  
Vol 109 (2) ◽  
pp. 525-533 ◽  
Author(s):  
S. Hird
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Fluorescence Microscopy ◽  
Actin Microfilaments ◽  
Cortical Actin ◽  
Daughter Cells ◽  
Actin Cortex ◽  
Asymmetrically Distributed ◽  
Cytoplasmic Determinants

The first division of the Caenorhabditis elegans embryo is unequal, generating daughter cells with distinct fates. The differences between the cells are believed to result from the partitioning of cytoplasmic determinants during the first cell cycle. Actin microfilaments play a critical, but poorly defined, role in this event. In this paper, the actin cortex in live embryos is studied during cytoplasmic localisation by fluorescently labelling microfilaments in oocytes and then using in vivo fluorescence microscopy to observe their behaviour. This reveals that there is a concerted movement of cortical actin to the anterior of the embryo at the time cytoplasmic localisation takes place. Furthermore, it is demonstrated that endogenous foci of F-actin are asymmetrically distributed following this event; these structures have previously been seen in fixed cortices. A model for the participation of the actin cytoskeleton in cytoplasmic localisation is presented based on these results.

scholarly journals Capping protein regulates actin dynamics during cytokinetic midbody maturation

2018 ◽  
Vol 115 (9) ◽  
pp. 2138-2143 ◽  
Author(s):  
Stephen J. Terry ◽  
Federico Donà ◽  
Paul Osenberg ◽  
Jeremy G. Carlton ◽  
Ulrike S. Eggert
Keyword(s):  
Actin Filaments ◽  
Actin Polymerization ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Capping Protein ◽  
Cytoskeletal Remodeling ◽  
Daughter Cells ◽  
Actin Capping Protein ◽  
Activity Loss ◽  
Actin Capping

During cytokinesis, a cleavage furrow generated by actomyosin ring contraction is restructured into the midbody, a platform for the assembly of the abscission machinery that controls the final separation of daughter cells. The polymerization state of F-actin is important during assembly, ingression, disassembly, and closure of the contractile ring and for the cytoskeletal remodeling that accompanies midbody formation and progression to abscission. Actin filaments must be cleared from the abscission sites before the final cut can take place. Although many conserved proteins interact with and influence the polymerization state of actin filaments, it is poorly understood how they regulate cytokinesis in higher eukaryotes. We report here that the actin capping protein (CP), a barbed end actin binding protein, participates in the control of actin polymerization during later stages of cytokinesis in human cells. Cells depleted of CP furrow and form early midbodies, but they fail cytokinesis. Appropriate recruitment of the ESCRT-III abscission machinery to the midbody is impaired, preventing the cell from progressing to the abscission stage. To generate actin filaments of optimal length, different actin nucleators, such as formins, balance CP’s activity. Loss of actin capping activity leads to excessive accumulation of formin-based linear actin filaments. Depletion of the formin FHOD1 results in partial rescue of CP-induced cytokinesis failure, suggesting that it can antagonize CP activity during midbody maturation. Our work suggests that the actin cytoskeleton is remodeled in a stepwise manner during cytokinesis, with different regulators at different stages required for successful progression to abscission.

scholarly journals A complex containing the Sm protein CAR-1 and the RNA helicase CGH-1 is required for embryonic cytokinesis in Caenorhabditis elegans

2005 ◽  
Vol 171 (2) ◽  
pp. 267-279 ◽  
Author(s):  
Anjon Audhya ◽  
Francie Hyndman ◽  
Ian X. McLeod ◽  
Amy S. Maddox ◽  
John R. Yates ◽  
...  
Keyword(s):  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Rna Binding ◽  
Rna Binding Protein ◽  
Rna Helicase ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Daughter Cells ◽  
Sm Protein ◽  
Spindle Structure

Cytokinesis completes cell division and partitions the contents of one cell to the two daughter cells. Here we characterize CAR-1, a predicted RNA binding protein that is implicated in cytokinesis. CAR-1 localizes to germline-specific RNA-containing particles and copurifies with the essential RNA helicase, CGH-1, in an RNA-dependent fashion. The atypical Sm domain of CAR-1, which directly binds RNA, is dispensable for CAR-1 localization, but is critical for its function. Inhibition of CAR-1 by RNA-mediated depletion or mutation results in a specific defect in embryonic cytokinesis. This cytokinesis failure likely results from an anaphase spindle defect in which interzonal microtubule bundles that recruit Aurora B kinase and the kinesin, ZEN-4, fail to form between the separating chromosomes. Depletion of CGH-1 results in sterility, but partially depleted worms produce embryos that exhibit the CAR-1–depletion phenotype. Cumulatively, our results suggest that CAR-1 functions with CGH-1 to regulate a specific set of maternally loaded RNAs that is required for anaphase spindle structure and cytokinesis.

scholarly journals Forces drive basement membrane invasion inCaenorhabditis elegans

2018 ◽  
Vol 115 (45) ◽  
pp. 11537-11542 ◽  
Author(s):  
Rodrigo Cáceres ◽  
Nagagireesh Bojanala ◽  
Laura C. Kelley ◽  
Jes Dreier ◽  
John Manzi ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Basement Membrane ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Force Production ◽  
Developmental Event ◽  
C Elegans ◽  
Anchor Cell

During invasion, cells breach basement membrane (BM) barriers with actin-rich protrusions. It remains unclear, however, whether actin polymerization applies pushing forces to help break through BM, or whether actin filaments play a passive role as scaffolding for targeting invasive machinery. Here, using the developmental event of anchor cell (AC) invasion inCaenorhabditis elegans, we observe that the AC deforms the BM and underlying tissue just before invasion, exerting forces in the tens of nanonewtons range. Deformation is driven by actin polymerization nucleated by the Arp2/3 complex and its activators, whereas formins and cross-linkers are dispensable. Delays in invasion upon actin regulator loss are not caused by defects in AC polarity, trafficking, or secretion, as appropriate markers are correctly localized in the AC even when actin is reduced and invasion is disrupted. Overall force production emerges from this study as one of the main tools that invading cells use to promote BM disruption inC. elegans.

scholarly journals Force-mediated cellular anisotropy and plasticity dictate the elongation dynamics of embryos

2021 ◽  
Vol 7 (27) ◽  
pp. eabg3264
Author(s):  
Chao Fang ◽  
Xi Wei ◽  
Xueying Shao ◽  
Yuan Lin
Keyword(s):  
Plastic Deformation ◽  
Caenorhabditis Elegans ◽  
Muscle Contraction ◽  
Dynamic Model ◽  
Actin Filaments ◽  
Actin Bundles ◽  
Abnormal Embryo ◽  
Intracellular Forces ◽  
Kinetics Of ◽  
Good Agreement

We developed a unified dynamic model to explain how cellular anisotropy and plasticity, induced by alignment and severing/rebundling of actin filaments, dictate the elongation dynamics of Caenorhabditis elegans embryos. It was found that the gradual alignment of F-actins must be synchronized with the development of intracellular forces for the embryo to elongate, which is then further sustained by muscle contraction–triggered plastic deformation of cells. In addition, we showed that preestablished anisotropy is essential for the proper onset of the process while defects in the integrity or bundling kinetics of actin bundles result in abnormal embryo elongation, all in good agreement with experimental observations.

Binary cell death decision regulated by unequal partitioning of Numb at mitosis

Development ◽  
2002 ◽  
Vol 129 (20) ◽  
pp. 4677-4684 ◽  
Author(s):  
Virginie Orgogozo ◽  
François Schweisguth ◽  
Yohanns Bellaïche
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Daughter Cell ◽  
Asymmetric Cell Divisions ◽  
Daughter Cells ◽  
Cell Divisions ◽  
Specific Manner ◽  
Asymmetric Divisions ◽  
Apoptotic Genes ◽  
Necessary And Sufficient

An important issue in Metazoan development is to understand the mechanisms that lead to stereotyped patterns of programmed cell death. In particular, cells programmed to die may arise from asymmetric cell divisions. The mechanisms underlying such binary cell death decisions are unknown. We describe here a Drosophila sensory organ lineage that generates a single multidentritic neuron in the embryo. This lineage involves two asymmetric divisions. Following each division, one of the two daughter cells expresses the pro-apoptotic genes reaper and grim and subsequently dies. The protein Numb appears to be specifically inherited by the daughter cell that does not die. Numb is necessary and sufficient to prevent apoptosis in this lineage. Conversely, activated Notch is sufficient to trigger death in this lineage. These results show that binary cell death decision can be regulated by the unequal segregation of Numb at mitosis. Our study also indicates that regulation of programmed cell death modulates the final pattern of sensory organs in a segment-specific manner.

scholarly journals Tropomodulin caps the pointed ends of actin filaments.

1994 ◽  
Vol 127 (6) ◽  
pp. 1627-1635 ◽  
Author(s):  
A Weber ◽  
C R Pennise ◽  
G G Babcock ◽  
V M Fowler
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Actin Filaments ◽  
Striated Muscle ◽  
Critical Concentration ◽  
Thin Filaments ◽  
Capping Protein ◽  
End Capping ◽  
Pointed End ◽  
A Site

Many proteins have been shown to cap the fast growing (barbed) ends of actin filaments, but none have been shown to block elongation and depolymerization at the slow growing (pointed) filament ends. Tropomodulin is a tropomyosin-binding protein originally isolated from red blood cells that has been localized by immunofluorescence staining to a site at or near the pointed ends of skeletal muscle thin filaments (Fowler, V. M., M. A., Sussman, P. G. Miller, B. E. Flucher, and M. P. Daniels. 1993. J. Cell Biol. 120: 411-420). Our experiments demonstrate that tropomodulin in conjunction with tropomyosin is a pointed end capping protein: it completely blocks both elongation and depolymerization at the pointed ends of tropomyosin-containing actin filaments in concentrations stoichiometric to the concentration of filament ends (Kd < or = 1 nM). In the absence of tropomyosin, tropomodulin acts as a "leaky" cap, partially inhibiting elongation and depolymerization at the pointed filament ends (Kd for inhibition of elongation = 0.1-0.4 microM). Thus, tropomodulin can bind directly to actin at the pointed filament end. Tropomodulin also doubles the critical concentration at the pointed ends of pure actin filaments without affecting either the rate of extent of polymerization at the barbed filament ends, indicating that tropomodulin does not sequester actin monomers. Our experiments provide direct biochemical evidence that tropomodulin binds to both the terminal tropomyosin and actin molecules at the pointed filament end, and is the long sought-after pointed end capping protein. We propose that tropomodulin plays a role in maintaining the narrow length distributions of the stable, tropomyosin-containing actin filaments in striated muscle and in red blood cells.

scholarly journals Molecular basis of synaptic vesicle cargo recognition by the endocytic sorting adaptor stonin 2

2007 ◽  
Vol 179 (7) ◽  
pp. 1497-1510 ◽  
Author(s):  
Nadja Jung ◽  
Martin Wienisch ◽  
Mingyu Gu ◽  
James B. Rand ◽  
Sebastian L. Müller ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Synaptic Vesicles ◽  
Molecular Basis ◽  
C Elegans ◽  
Evolutionarily Conserved ◽  
Molecular Determinants ◽  
Direct Association ◽  
Endocytic Sorting ◽  
Synaptotagmin 1 ◽  
Stonin 2

Synaptic transmission depends on clathrin-mediated recycling of synaptic vesicles (SVs). How select SV proteins are targeted for internalization has remained elusive. Stonins are evolutionarily conserved adaptors dedicated to endocytic sorting of the SV protein synaptotagmin. Our data identify the molecular determinants for recognition of synaptotagmin by stonin 2 or its Caenorhabditis elegans orthologue UNC-41B. The interaction involves the direct association of clusters of basic residues on the surface of the cytoplasmic domain of synaptotagmin 1 and a β strand within the μ–homology domain of stonin 2. Mutation of K783, Y784, and E785 to alanine within this stonin 2 β strand results in failure of the mutant stonin protein to associate with synaptotagmin, to accumulate at synapses, and to facilitate synaptotagmin internalization. Synaptotagmin-binding–defective UNC-41B is unable to rescue paralysis in C. elegans stonin mutant animals, suggesting that the mechanism of stonin-mediated SV cargo recognition is conserved from worms to mammals.

Sign in / Sign up

Export Citation Format

Share Document