title: Many roads to symmetry breaking: molecular mechanisms and theoretical models of yeast cell polarity.
abstract: Mathematical modeling has been instrumental in identifying common principles of cell polarity across diverse systems. These principles include positive feedback loops that are required to destabilize a spatially uniform state of the cell. The conserved small G-protein Cdc42 is a master regulator of eukaryotic cellular polarization. Here we discuss recent developments in studies of Cdc42 polarization in budding and fission yeasts and demonstrate that models describing symmetry-breaking polarization can be classified into six minimal classes based on the structure of positive feedback loops that activate and localize Cdc42. Owing to their generic system-independent nature, these model classes are also likely to be relevant for the G-protein-based symmetry-breaking systems of higher eukaryotes. We review experimental evidence pro et contra different theoretically plausible models and conclude that several parallel and non-mutually exclusive mechanisms are likely involved in cellular polarization of yeasts. This potential redundancy needs to be taken into consideration when interpreting the results of recent cell-rewiring studies.
authors.affiliation: Center for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom Andrew.Goryachev@ed.ac.uk.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Goryachev
authors.affiliation: Center for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom.
authors.forename: Marcin
authors.initials: M
authors.lastname: Leda
mesh_terms: D002455:Cell Division; D016764:Cell Polarity / Q000235:genetics* / Q000502:physiology*; D025461:Feedback, Physiological; D008954:Models, Biological; D008962:Models, Theoretical; D004718:Saccharomycetales / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism* / Q000502:physiology
chemical_list: D020764:cdc42 GTP-Binding Protein