The PAR network: redundancy and robustness in a symmetry-breaking system

@article{Motegi2013ThePN,
  title={The PAR network: redundancy and robustness in a symmetry-breaking system},
  author={Fumio Motegi and Geraldine Seydoux},
  journal={Philosophical Transactions of the Royal Society B: Biological Sciences},
  year={2013},
  volume={368}
}
  • F. Motegi, G. Seydoux
  • Published 5 November 2013
  • Biology
  • Philosophical Transactions of the Royal Society B: Biological Sciences
To become polarized, cells must first ‘break symmetry’. Symmetry breaking is the process by which an unpolarized, symmetric cell develops a singularity, often at the cell periphery, that is used to develop a polarity axis. The Caenorhabditis elegans zygote breaks symmetry under the influence of the sperm-donated centrosome, which causes the PAR polarity regulators to sort into distinct anterior and posterior cortical domains. Modelling analyses have shown that cortical flows induced by the… 
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TLDR
A reaction-diffusion model in a realistic cell geometry is formulated and the crucial role of geometry in self-organized protein pattern formation is revealed, based on the generic dependence of intracellular pattern-forming processes on the local ratio of membrane surface to cytosolic volume.
Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos.
TLDR
The unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos is discussed, a refined model of centrosome-dependent symmetry breaking is proposed and a model that directs symmetry breaking through direct regulation of Rho-dependent contractility is proposed.
Centrosome Aurora A gradient ensures a single PAR-2 polarity axis by regulating RhoGEF ECT-2 localization in C. elegans embryos
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This study unravels a novel insight whereby an evolutionarily conserved kinase Aurora A inhibits promiscuous PAR-2 domain formation and ensures singularity in the polarity establishment axis.
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How actomyosin and microtubule networks serve as common biomechanical systems with inherent abilities to drive spontaneous symmetry breaking and self-organization of molecular assemblies into polarized entities on mesoscopic scales is discussed.
Centrosome Aurora A regulates RhoGEF ECT-2 localisation and ensures a single PAR-2 polarity axis in C. elegans embryos
TLDR
A novel insight is provided into how an evolutionarily conserved centrosome Aurora A kinase inhibits promiscuous PAR-2 domain formation to ensure singularity in the polarity establishment axis in C. elegans embryos.
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First evidence that mechanical contact of posterior follicle cells with the oocyte cortex causes the posterior exclusion of Bazooka and maintains oocyte polarity is provided and it is suggested that cell-cell contact mechanics modulates Par protein binding sites at the oocytes cortex.
Geometric cues stabilise long-axis polarisation of PAR protein patterns in C. elegans
TLDR
A reaction-diffusion model in realistic cell geometry is presented and it is found that long-axis polarisation is promoted by cytosolic dephosphorylation at onset and its steady state determined by minimising the length of the aPAR-pPAR interface.
Dynamic Opposition of Clustered Proteins Stabilizes Cortical Polarity in the C. elegans Zygote.
Going with the flow: insights from Caenorhabditis elegans zygote polarization
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Recent findings on the interplay between actomyosin flow and the PAR patterning networks in the polarization of the C. elegans zygote are reviewed and how these discoveries and developed methods are shaping the understanding of other flow-dependent polarizing systems are discussed.
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