Introduction
During early embryonic development polarity and asymmetric division are essential elements. In this paper Lars Hubatch et al. showed the significance of cell size in stem cell-like germ lineage in C elegans embryo cells. They found a threshold in the cell-size, able to induce the state of polarity or not. It means that a reduction in the cell size can then disrupt cell polarity, thus, involving a change of fate. This also implies the capacity of cells to obtain information about their geometry and its impact on intracellular processes leading to decisions like division. This study supports the importance of the physical environment and potential adaptation to diseases such as cancer, and the understanding of cell fate decision-making.
Ultra fast temperature shift device for in vitro experiments under microscopy
Abstract
“Reaction–diffusion networks underlie pattern formation in a range of biological contexts, from morphogenesis of organisms to the polarization of individual cells. One requirement for such molecular networks is that output patterns be scaled to system size. At the same time, kinetic properties of constituent molecules constrain the ability of networks to adapt to size changes. Here, we explore these constraints and the consequences thereof within the conserved PAR cell polarity network. Using the stem-cell-like germ lineage of the C elegans embryo cells as a model, we find that the behavior of PAR proteins fails to scale with cell size. Theoretical analysis demonstrates that this lack of scaling results in a size threshold below which polarity is destabilized, yielding an unpolarized system. In empirically constrained models, this threshold occurs near the size at which germ lineage cells normally switch between asymmetric and symmetric modes of division. Consistent with cell size limiting polarity and division asymmetry, genetic or physical reduction in germ lineage cell size is sufficient to trigger loss of polarity in normally polarizing cells at predicted size thresholds. Physical limits of polarity networks may be one mechanism by which cells read out geometrical features to inform cell fate decisions.”
References
FAQ
Polarity and asymmetric division are noted as important parts of early embryonic development. This process was studied in the stem-cell-like germ lineage of C. elegans embryo cells. It was found that cell size is a main factor. A reduction in the size of a cell can disrupt its polarity. This disruption, in turn, involves a change in the cell’s ultimate fate. The conserved PAR cell polarity network is part of this mechanism. The behaviour of the proteins in this network fails to scale with the size of the cell. This lack of scaling creates a size threshold. Below this specific size, polarity is destabilized, and an unpolarized state is the result.
Reaction-diffusion networks are known to underlie pattern formation in biological contexts. This applies to the polarization of individual cells. A requirement for such molecular networks is that their output patterns should be scaled to the system’s size. At the same time, the kinetic properties of the molecules involved constrain the network’s ability to adapt to size changes. The PAR cell polarity network is a conserved example. In the C. elegans germ lineage, the behaviour of these PAR proteins was found to fail to scale with cell size. Theoretical analysis demonstrated this lack of scaling results in a size threshold. Below this point, the system becomes unpolarized.
A cell-size threshold was identified in the stem-cell-like germ lineage of C. elegans. This threshold determines if the cell can induce a state of polarity. A reduction in cell size below this point is sufficient to disrupt polarity. This disruption involves a change in the cell’s fate. In models that were constrained by empirical data, this threshold was found to be near a specific size. This size is where the germ lineage cells normally switch their mode of division. They change from an asymmetric to a symmetric division type. This finding is consistent with the idea that cell size limits both polarity and the asymmetry of division.
The concept that cell size limits polarity and division asymmetry was tested. It was found that reducing the size of germ lineage cells was enough to trigger a loss of polarity. This loss of polarity was observed in cells that are normally polarizing. This effect was caused by either genetic or physical reduction of the cell’s size. The loss of polarity occurred at the size thresholds that had been predicted by theoretical analysis. This result supports the idea that the physical environment is important. It may be one mechanism by which cells can read out geometrical features. This information is then used to inform cell fate decisions.
