scholarly journals Src activation decouples cell division orientation from cell geometry in mammalian cells

Biomaterials ◽  
2018 ◽  
Vol 170 ◽  
pp. 82-94
Author(s):  
Xiaoyan Sun ◽  
Hongsheng Qi ◽  
Xiuzhen Zhang ◽  
Li Li ◽  
Jiaping Zhang ◽  
...  
Keyword(s):  
Cell Division ◽  
Mammalian Cells ◽  
Cell Geometry ◽  
Src Activation

scholarly journals SpyAD, a Moonlighting Protein of Group A Streptococcus Contributing to Bacterial Division and Host Cell Adhesion

2014 ◽  
Vol 82 (7) ◽  
pp. 2890-2901 ◽  
Author(s):  
Marilena Gallotta ◽  
Giovanni Gancitano ◽  
Giampiero Pietrocola ◽  
Marirosa Mora ◽  
Alfredo Pezzicoli ◽  
...  
Keyword(s):  
Cell Division ◽  
Mammalian Cells ◽  
Group A Streptococcus ◽  
Host Cells ◽  
Knockout Mutant ◽  
Content Type ◽  
Moonlighting Protein ◽  
Group A

ABSTRACTGroup A streptococcus (GAS) is a human pathogen causing a wide repertoire of mild and severe diseases for which no vaccine is yet available. We recently reported the identification of three protein antigens that in combination conferred wide protection against GAS infection in mice. Here we focused our attention on the characterization of one of these three antigens, Spy0269, a highly conserved, surface-exposed, and immunogenic protein of unknown function. Deletion of thespy0269gene in a GAS M1 isolate resulted in very long bacterial chains, which is indicative of an impaired capacity of the knockout mutant to properly divide. Confocal microscopy and immunoprecipitation experiments demonstrated that the protein was mainly localized at the cell septum and could interactin vitrowith the cell division protein FtsZ, leading us to hypothesize that Spy0269 is a member of the GAS divisome machinery. Predicted structural domains and sequence homologies with known streptococcal adhesins suggested that this antigen could also play a role in mediating GAS interaction with host cells. This hypothesis was confirmed by showing that recombinant Spy0269 could bind to mammalian epithelial cellsin vitroand thatLactococcus lactisexpressing Spy0269 on its cell surface could adhere to mammalian cellsin vitroand to mice nasal mucosain vivo. On the basis of these data, we believe that Spy0269 is involved both in bacterial cell division and in adhesion to host cells and we propose to rename this multifunctional moonlighting protein as SpyAD (StreptococcuspyogenesAdhesion andDivision protein).

Overexpression Phenotypes of Plk1 and Ndrg2 in Schizosaccharomyces Pombe: Fission Yeast System for Mammalian Gene Study

2005 ◽  
Vol 277-279 ◽  
pp. 1-6 ◽  
Author(s):  
Young Joo Jang ◽  
Young Sook Kil ◽  
Jee Hee Ahn ◽  
Jae Hoon Ji ◽  
Jong Seok Lim ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Rna Splicing ◽  
Mammalian Cells ◽  
Protein Modification ◽  
Genetic System ◽  
Functional Study ◽  
Mammalian Genes

The fission yeast, Schizosaccharomyces pombe is a single-celled free-living fungus that shares many features with cells of more complicated eukaryotes. Many of the genes required for the cell-cycle control, proteolysis, protein modification, and RNA splicing are highly conserved with those of higher eukaryotes. Moreover, fission yeast has the merit of genetics and its genetic system is already well characterized. As such, the current study evaluated the use of a fission yeast system as a tool for the functional study of mammalian genes and attempted to set up an assay system for novel genes. Since the phenotypes of a deletion mutant and the overexpression of a gene are generally analyzed for a functional study of specific genes in yeast, the present study used overexpression phenotypes to study the functions of mammalian genes. Therefore, based on using a thiamine-repressive promoter, two mammalian genes were expressed in fission yeast, and their overexpressed phenotypes compared with those in mammalian cells. The phenotypes resulting from overexpression were analyzed using a FACS, which analyzes the DNA contents, and a microscope. One of the selected genes was the mammalian Polo-like kinase 1 (Plk1), which is activated and plays a role in the mitotic phase of the cell division cycle. The overexpression of various constructs of Plk1 in the HeLa cells caused cell cycle defects, suggesting that the ectopic Plk1s blocked the endogenous Plk1 in the cells. As expected, when the constructs were overexpressed in the fission yeast system, the cells were arrested in mitosis and defected at the end of mitosis. As such, this data suggests that the Plk1-overexpressed phenotypes were similar in the mammalian cells and the fission yeast, thereby enabling the mammalian Plk1 functions to be approximated in the fission yeast. The other selected gene was the N-Myc downstream-regulated gene 2 (ndrg2), which is upregulated during cell differentiation, yet still not well characterized. When the ndrg2 gene was overexpressed in the fission yeast, the cells contained multi-septa. The septa were positioned well, yet their number increased per cell. Therefore, this gene was speculated to block cell division in the last stage of the cell cycle, making the phenotype potentially useful for explaining cell growth and differentiation in mammalian cells. Accordingly, fission yeast is demonstrated to be an appropriate species for the functional study of mammalian genes.

The structural mechanics of cell division in Trypanosoma brucei

2008 ◽  
Vol 36 (3) ◽  
pp. 421-424 ◽  
Author(s):  
Sue Vaughan ◽  
Keith Gull
Keyword(s):  
Cell Division ◽  
Trypanosoma Brucei ◽  
Mammalian Cells ◽  
Reverse Genetics ◽  
Protozoan Parasite ◽  
Cell Types ◽  
Single Copy ◽  
Structural Mechanics ◽  
Sub Saharan Africa ◽  
Mammalian Host

Undoubtedly, there are fundamental processes driving the structural mechanics of cell division in eukaryotic organisms that have been conserved throughout evolution and are being revealed by studies on organisms such as yeast and mammalian cells. Precision of structural mechanics of cytokinesis is however probably no better illustrated than in the protozoa. A dramatic example of this is the protozoan parasite Trypanosoma brucei, a unicellular flagellated parasite that causes a devastating disease (African sleeping sickness) across Sub-Saharan Africa in both man and animals. As trypanosomes migrate between and within a mammalian host and the tsetse vector, there are periods of cell proliferation and cell differentiation involving at least five morphologically distinct cell types. Much of the existing cytoskeleton remains intact during these processes, necessitating a very precise temporal and spatial duplication and segregation of the many single-copy organelles. This structural precision is aiding progress in understanding these processes as we apply the excellent reverse genetics and post-genomic technologies available in this system. Here we outline our current understanding of some of the structural aspects of cell division in this fascinating organism.

Nocodazole and cytochalasin D induce tetraploidy in mammalian cells

1984 ◽  
Vol 246 (1) ◽  
pp. C154-C156 ◽  
Author(s):  
G. W. Zieve
Keyword(s):  
Cell Division ◽  
Mammalian Cells ◽  
Cytochalasin D ◽  
Microtubule Assembly ◽  
Reversible Inhibitor ◽  
Cleavage Furrow ◽  
Synchronized Cells ◽  
Cells In Culture ◽  
Wide Range

Nocodazole, a rapidly reversible inhibitor of microtubule assembly is useful for preparing mammalian cells synchronized at all stages of mitosis. When synchronized cells are allowed to progress through mitosis in the presence of cytochalasin D, the cleavage furrow is inhibited and dikaryon cells are formed. These cells become homogeneous populations of stable mononuclear tetraploid cells after the following cell division. This procedure is applicable to a wide range of mammalian cells in culture.

scholarly journals Cell growth dilutes the cell cycle inhibitor Rb to trigger cell division

2018 ◽  
Author(s):  
Evgeny Zatulovskiy ◽  
Daniel F. Berenson ◽  
Benjamin R. Topacio ◽  
Jan M. Skotheim
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Cell Growth ◽  
Cell Size ◽  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Inverse Correlation ◽  
Cell Types ◽  
Similar Amount ◽  
Cell Cycle Inhibitor

Cell size is fundamental to function in different cell types across the human body because it sets the scale of organelle structures, biosynthesis, and surface transport1,2. Tiny erythrocytes squeeze through capillaries to transport oxygen, while the million-fold larger oocyte divides without growth to form the ~100 cell pre-implantation embryo. Despite the vast size range across cell types, cells of a given type are typically uniform in size likely because cells are able to accurately couple cell growth to division3–6. While some genes whose disruption in mammalian cells affects cell size have been identified, the molecular mechanisms through which cell growth drives cell division have remained elusive7–12. Here, we show that cell growth acts to dilute the cell cycle inhibitor Rb to drive cell cycle progression from G1 to S phase in human cells. In contrast, other G1/S regulators remained at nearly constant concentration. Rb is a stable protein that is synthesized during S and G2 phases in an amount that is independent of cell size. Equal partitioning to daughter cells of chromatin bound Rb then ensures that all cells at birth inherit a similar amount of Rb protein. RB overexpression increased cell size in tissue culture and a mouse cancer model, while RB deletion decreased cell size and removed the inverse correlation between cell size at birth and the duration of G1 phase. Thus, Rb-dilution by cell growth in G1 provides a long-sought cell autonomous molecular mechanism for cell size homeostasis.

scholarly journals TheNitrosopumilus maritimusCdvB, but Not FtsZ, Assembles into Polymers

Archaea ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Kian-Hong Ng ◽  
Vinayaka Srinivas ◽  
Ramanujam Srinivasan ◽  
Mohan Balasubramanian
Keyword(s):  
Cell Division ◽  
Heterologous Expression ◽  
Fission Yeast ◽  
Mammalian Cells ◽  
Expression System ◽  
Related Protein ◽  
Heterologous Expression System

Euryarchaeota and Crenarchaeota are two major phyla of archaea which use distinct molecular apparatuses for cell division. Euryarchaea make use of the tubulin-related protein FtsZ, while Crenarchaea, which appear to lack functional FtsZ, employ the Cdv (cell division) components to divide. Ammonia oxidizing archaeon (AOA)Nitrosopumilus maritimusbelongs to another archaeal phylum, the Thaumarchaeota, which has both FtsZ and Cdv genes in the genome. Here, we used a heterologous expression system to characterize FtsZ and Cdv proteins fromN. maritimusby investigating the ability of these proteins to form polymers. We show that one of the Cdv proteins inN. maritimus, the CdvB (Nmar_0816), is capable of forming stable polymers when expressed in fission yeast. TheN. maritimusCdvB is also capable of assembling into filaments in mammalian cells. However,N. maritimusFtsZ does not assemble into polymers in our system. The ability of CdvB, but not FtsZ, to polymerize is consistent with a recent finding showing that several Cdv proteins, but not FtsZ, localize to the mid-cell site in the dividingN. maritimus. Thus, we propose that it is Cdv proteins, rather than FtsZ, that function as the cell division apparatus inN. maritimus.

scholarly journals Lunasin: A Novel Cancer Preventive Seed Peptide that Modifies Chromatin

2008 ◽  
Vol 91 (4) ◽  
pp. 932-935 ◽  
Author(s):  
Ben O de Lumen
Keyword(s):  
Growth Rate ◽  
Cell Death ◽  
Cell Division ◽  
Skin Cancer ◽  
Mammalian Cells ◽  
Constitutive Expression ◽  
Epigenetic Mechanism ◽  
Transformed Cells ◽  
Chemical Carcinogens ◽  
Core Histones

Abstract Lunasin is a novel cancer preventive peptide whose efficacy against chemical carcinogens and oncogenes has been demonstrated in mammalian cells and a skin cancer mouse model. In contrast, constitutive expression of the lunasin gene in mammalian cells leads to arrest of cell division and cell death. Isolated and characterized in soy, lunasin peptide is also documented in barley and wheat and is predicted to be present in many more seeds because of its possible role in seed development. Initial studies show that lunasin is bioavailable in mice when orally ingested. Lunasin internalizes into mammalian cells within minutes of exogenous application, and localizes in the nucleus after 18 h. It inhibits acetylation of core histones in mammalian cells but does not affect the growth rate of normal and established cancer cell lines. An epigenetic mechanism of action is proposed whereby lunasin selectively kills cells being transformed or newly transformed cells by binding to deacetylated core histones exposed by the transformation event, disrupting the dynamics of histone acetylationdeacetylation.

scholarly journals The ARF GAP ELMOD2 acts with different GTPases to regulate centrosomal microtubule nucleation and cytokinesis

2020 ◽  
Vol 31 (18) ◽  
pp. 2070-2091 ◽  
Author(s):  
Rachel E. Turn ◽  
Michael P. East ◽  
Rytis Prekeris ◽  
Richard A. Kahn
Keyword(s):  
Cell Division ◽  
Mammalian Cells ◽  
Microtubule Nucleation

The ELMOD2 gene has been linked to a number of human pathologies and encodes an ∼32 kDa protein that acts from multiple sites in mammalian cells. Knocking out the protein in fibroblasts causes defects in microtubules and cell division.

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