scholarly journals The Role of Cytoplasmic MEX-5/6 Polarity in Asymmetric Cell Division

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
Sungrim Seirin-Lee
Keyword(s):  
Mathematical Model ◽  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Cell Membrane ◽  
Mother Cell ◽  
Asymmetric Cell Division ◽  
Transmembrane Protein ◽  
Cytoplasmic Protein ◽  
Cell Geometry

AbstractIn the process of asymmetric cell division, the mother cell induces polarity in both the membrane and the cytosol by distributing substrates and components asymmetrically. Such polarity formation results from the harmonization of the upstream and downstream polarities between the cell membrane and the cytosol. MEX-5/6 is a well-investigated downstream cytoplasmic protein, which is deeply involved in the membrane polarity of the upstream transmembrane protein PAR in the Caenorhabditis elegans embryo. In contrast to the extensive exploration of membrane PAR polarity, cytoplasmic polarity is poorly understood, and the precise contribution of cytoplasmic polarity to the membrane PAR polarity remains largely unknown. In this study, we explored the interplay between the cytoplasmic MEX-5/6 polarity and the membrane PAR polarity by developing a mathematical model that integrates the dynamics of PAR and MEX-5/6 and reflects the cell geometry. Our investigations show that the downstream cytoplasmic protein MEX-5/6 plays an indispensable role in causing a robust upstream PAR polarity, and the integrated understanding of their interplay, including the effect of the cell geometry, is essential for the study of polarity formation in asymmetric cell division.

scholarly journals Robustness of differentiation cascades with symmetric stem cell division

2014 ◽  
Vol 11 (95) ◽  
pp. 20140264 ◽  
Author(s):  
Daniel Sánchez-Taltavull ◽  
Tomás Alarcón
Keyword(s):  
Mathematical Model ◽  
Cell Division ◽  
Asymmetric Cell Division ◽  
Tissue Homeostasis ◽  
Intermediate Cell ◽  
Self Renewal ◽  
Cell Numbers ◽  
Cell Compartments ◽  
Stem Cell Division

Stem cells (SCs) perform the task of maintaining tissue homeostasis by both self-renewal and differentiation. While it has been argued that SCs divide asymmetrically, there is also evidence that SCs undergo symmetric division. Symmetric SC division has been speculated to be key for expanding cell numbers in development and regeneration after injury. However, it might lead to uncontrolled growth and malignancies such as cancer. In order to explore the role of symmetric SC division, we propose a mathematical model of the effect of symmetric SC division on the robustness of a population regulated by a serial differentiation cascade and we show that this may lead to extinction of such population. We examine how the extinction likelihood depends on defining characteristics of the population such as the number of intermediate cell compartments. We show that longer differentiation cascades are more prone to extinction than systems with less intermediate compartments. Furthermore, we have analysed the possibility of mixed symmetric and asymmetric cell division against invasions by mutant invaders in order to find optimal architecture. Our results show that more robust populations are those with unfrequent symmetric behaviour.

scholarly journals Regulation of the meiotic divisions of mammalian oocytes and eggs

2018 ◽  
Vol 46 (4) ◽  
pp. 797-806 ◽  
Author(s):  
Jessica R. Sanders ◽  
Keith T. Jones
Keyword(s):  
Cell Division ◽  
Luteinizing Hormone ◽  
Spindle Assembly Checkpoint ◽  
Asymmetric Cell Division ◽  
Homologous Chromosomes ◽  
Mammalian Oocyte ◽  
Cellular Events ◽  
The Hours ◽  
Meiosis I

Initiated by luteinizing hormone and finalized by the fertilizing sperm, the mammalian oocyte completes its two meiotic divisions. The first division occurs in the mature Graafian follicle during the hours preceding ovulation and culminates in an extreme asymmetric cell division and the segregation of the two pairs of homologous chromosomes. The newly created mature egg rearrests at metaphase of the second meiotic division prior to ovulation and only completes meiosis following a Ca2+ signal initiated by the sperm at gamete fusion. Here, we review the cellular events that govern the passage of the oocyte through meiosis I with a focus on the role of the spindle assembly checkpoint in regulating its timing. In meiosis II, we examine how the egg achieves its arrest and how the fertilization Ca2+ signal allows the initiation of embryo development.

Asymmetric cell division and differentiation; fern spore germination as a model. II. Ultrastructural studies

1985 ◽  
Vol 86 ◽  
pp. 227-230
Author(s):  
Alix R. Bassel
Keyword(s):  
Cell Division ◽  
Metal Binding ◽  
Asymmetric Cell Division ◽  
Red Light ◽  
Nuclear Migration ◽  
Silver Stain ◽  
Metal Binding Sites ◽  
Ultrastructural Studies ◽  
Fern Spore Germination

SynopsisThe germination of Onoclea spores is a model system with many advantages for the study of asymmetric cell division and cellular differentiation. Our results suggest that both microtubules and a lipophilic site are important in the nuclear migration to one end of the spore prior to asymmetric cell division. A metalbinding region containing pore-like structures in the proximal face of the spore coat may be a source of the inherent polarity of the spore. The pattern of endogenous metal binding during germination has been characterised using a sulphide-silver stain. Metal-binding sites are described in a differentiating system in which polarity is imposed externally using polarised red light. The possibility of a role of ion gradients in determining the direction of nuclear migration is discussed.

OOC-3, a novel putative transmembrane protein required for establishment of cortical domains and spindle orientation in the P(1) blastomere of C. elegans embryos

Development ◽  
2000 ◽  
Vol 127 (10) ◽  
pp. 2063-2073 ◽  
Author(s):  
S. Pichler ◽  
P. Gonczy ◽  
H. Schnabel ◽  
A. Pozniakowski ◽  
A. Ashford ◽  
...  
Keyword(s):  
Cell Division ◽  
Asymmetric Cell Division ◽  
Transmembrane Protein ◽  
Cell Stage ◽  
Par Proteins ◽  
Asymmetric Cell Divisions ◽  
C Elegans ◽  
Membrane Compartment ◽  
Chromosome Ii

Asymmetric cell divisions require the establishment of an axis of polarity, which is subsequently communicated to downstream events. During the asymmetric cell division of the P(1) blastomere in C. elegans, establishment of polarity depends on the establishment of anterior and posterior cortical domains, defined by the localization of the PAR proteins, followed by the orientation of the mitotic spindle along the previously established axis of polarity. To identify genes required for these events, we have screened a collection of maternal-effect lethal mutations on chromosome II of C. elegans. We have identified a mutation in one gene, ooc-3, with mis-oriented division axes at the two-cell stage. Here we describe the phenotypic and molecular characterization of ooc-3. ooc-3 is required for the correct localization of PAR-2 and PAR-3 cortical domains after the first cell division. OOC-3 is a novel putative transmembrane protein, which localizes to a reticular membrane compartment, probably the endoplasmic reticulum, that spans the whole cytoplasm and is enriched on the nuclear envelope and cell-cell boundaries. Our results show that ooc-3 is required to form the cortical domains essential for polarity after cell division.

The role of GlsA in the evolution of asymmetric cell division in the green alga Volvox carteri

2003 ◽  
Vol 213 (7) ◽  
pp. 328-335 ◽  
Author(s):  
Qian Cheng ◽  
Rachel Fowler ◽  
Lai-wa Tam ◽  
Lisseth Edwards ◽  
Stephen M. Miller
Keyword(s):  
Cell Division ◽  
Green Alga ◽  
Asymmetric Cell Division ◽  
Volvox Carteri
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