scholarly journals How cells determine the number of polarity sites

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jian-geng Chiou ◽  
Kyle D Moran ◽  
Daniel J Lew
Keyword(s):  
Design Principle ◽  
Fundamental Question ◽  
Yeast Cells ◽  
Regulatory Mechanisms ◽  
Saturation Point ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
Theoretical Analyses ◽  
Novel Design ◽  
Insight Into

The diversity of cell morphologies arises, in part, through regulation of cell polarity by Rho-family GTPases. A poorly understood but fundamental question concerns the regulatory mechanisms by which different cells generate different numbers of polarity sites. Mass-conserved activator-substrate (MCAS) models that describe polarity circuits develop multiple initial polarity sites, but then those sites engage in competition, leaving a single winner. Theoretical analyses predicted that competition would slow dramatically as GTPase concentrations at different polarity sites increase towards a 'saturation point', allowing polarity sites to coexist. Here, we test this prediction using budding yeast cells, and confirm that increasing the amount of key polarity proteins results in multiple polarity sites and simultaneous budding. Further, we elucidate a novel design principle whereby cells can switch from competition to equalization among polarity sites. These findings provide insight into how cells with diverse morphologies may determine the number of polarity sites.

scholarly journals How cells determine the number of polarity sites

2020 ◽  
Author(s):  
Jian-geng Chiou ◽  
Kyle D. Moran ◽  
Daniel J. Lew
Keyword(s):  
Design Principle ◽  
Theoretical Models ◽  
Mechanistic Models ◽  
Saturation Point ◽  
Rho Family Gtpases ◽  
Model Predictions ◽  
Rho Family ◽  
Novel Design ◽  
Insight Into

AbstractThe diversity of cell morphologies arises, in part, through regulation of cell polarity by Rho-family GTPases. A poorly understood but fundamental question concerns the regulatory mechanisms by which different cells can generate different numbers of polarity sites. Theoretical models of polarity circuits develop multiple initial polarity sites, but then those sites engage in competition, leaving a single winner. The timescale of competition slows dramatically as GTPase concentrations at polarity sites approach a “saturation point”, allowing multiple sites to coexist. Here, we show that these principles hold in more complex mechanistic models of the Saccharomyces cerevisiae polarity machinery, and confirm model predictions in vivo. Further, we elucidate a novel design principle whereby cells can switch from competition to equalization among polarity sites. These findings provide insight into how cells determine the number of polarity sites.

scholarly journals Rho Family of Ras-Like GTPases in Early-Branching Animals

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2279
Author(s):  
Silvestar Beljan ◽  
Maja Herak Bosnar ◽  
Helena Ćetković
Keyword(s):  
Current Knowledge ◽  
Molecular Switches ◽  
Cellular Responses ◽  
Small Gtpases ◽  
Rho Family Gtpases ◽  
History Of ◽  
Rho Family ◽  
Major Branch ◽  
External Signals ◽  
Insight Into

Non-bilaterian animals consist of four phyla; Porifera, Cnidaria, Ctenophora, and Placozoa. These early-diverging animals are crucial for understanding the evolution of the entire animal lineage. The Rho family of proteins make up a major branch of the Ras superfamily of small GTPases, which function as key molecular switches that play important roles in converting and amplifying external signals into cellular responses. This review represents a compilation of the current knowledge on Rho-family GTPases in non-bilaterian animals, the available experimental data about their biochemical characteristics and functions, as well as original bioinformatics analysis, in order to gain a general insight into the evolutionary history of Rho-family GTPases in simple animals.

Mapping the proximity interaction network of the Rho-family GTPases reveals signalling pathways and regulatory mechanisms

2019 ◽  
Vol 22 (1) ◽  
pp. 120-134 ◽  
Author(s):  
Halil Bagci ◽  
Neera Sriskandarajah ◽  
Amélie Robert ◽  
Jonathan Boulais ◽  
Islam E. Elkholi ◽  
...  
Keyword(s):  
Interaction Network ◽  
Regulatory Mechanisms ◽  
Signalling Pathways ◽  
Rho Family Gtpases ◽  
Rho Family

scholarly journals MgcRacGAP interacts with cingulin and paracingulin to regulate Rac1 activation and development of the tight junction barrier during epithelial junction assembly

2014 ◽  
Vol 25 (13) ◽  
pp. 1995-2005 ◽  
Author(s):  
Laurent Guillemot ◽  
Diego Guerrera ◽  
Domenica Spadaro ◽  
Rocio Tapia ◽  
Lionel Jond ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Cell Junctions ◽  
Rho Family Gtpases ◽  
Exogenous Expression ◽  
Rho Family ◽  
Rho Gef ◽  
Insight Into ◽  
Darby Canine Kidney

The regulation of Rho-family GTPases is crucial to direct the formation of cell–cell junctions and tissue barriers. Cingulin (CGN) and paracingulin (CGNL1) control RhoA activation in epithelial cells by interacting with RhoA guanidine exchange factors. CGNL1 depletion also inhibits Rac1 activation during junction assembly. Here we show that, unexpectedly, Madin–Darby canine kidney epithelial cells depleted of both CGN and CGNL1 (double-KD cells) display normal Rac1 activation and tight junction (TJ) formation, despite decreased junctional recruitment of the Rac1 activator Tiam1. The expression of the Rac1 inhibitor MgcRacGAP is decreased in double-KD cells, and the barrier development and Rac1 activation phenotypes are rescued by exogenous expression of MgcRacGAP. MgcRacGAP colocalizes with CGN and CGNL1 at TJs and forms a complex and interacts directly in vitro with CGN and CGNL1. Depletion of either CGN or CGNL1 in epithelial cells results in decreased junctional localization of MgcRacGAP but not of ECT2, a centralspindlin-interacting Rho GEF. These results provide new insight into coordination of Rho-family GTPase activities at junctions, since apical accumulation of CGN and CGNL1 at TJs during junction maturation provides a mechanism to spatially restrict down-regulation of Rac1 activation through the recruitment of MgcRacGAP.

scholarly journals Author Correction: Mapping the proximity interaction network of the Rho-family GTPases reveals signalling pathways and regulatory mechanisms

2020 ◽  
Vol 22 (3) ◽  
pp. 353-353
Author(s):  
Halil Bagci ◽  
Neera Sriskandarajah ◽  
Amélie Robert ◽  
Jonathan Boulais ◽  
Islam E. Elkholi ◽  
...  
Keyword(s):  
Interaction Network ◽  
Regulatory Mechanisms ◽  
Signalling Pathways ◽  
Rho Family Gtpases ◽  
Rho Family

The role of Rho-family GTPases in human glioblastomas

2004 ◽  
Vol 31 (S 1) ◽  
Author(s):  
S Seta ◽  
M Herr ◽  
S Horn ◽  
D Koch ◽  
T Vogt ◽  
...  
Keyword(s):  
Rho Family Gtpases ◽  
Rho Family

Revising Inconsistent Concepts

2017 ◽  
Author(s):  
Kevin Scharp ◽  
Stewart Shapiro ◽  
Bradley Armour-Garb
Keyword(s):  
Fundamental Question ◽  
Concept Of Truth ◽  
Constitutive Principles ◽  
Insight Into

This chapter investigates the question of when it is reasonable to replace an inconsistent concept. After surveying a number of proposals for how one might understand constitutive principles, it goes on to endorse Burgess’s (2004) account of being pragmatically analytic, as a possible source of insight into constitutive principles. The chapter then raises a question: If truth is an inconsistent concept, does it need to be replaced? According to the argument in the chapter, when an inconsistent concept paralyzes valuable projects, it is time to replace it. And if we are to replace a concept, our replacement should be able to do the work that the inconsistency-yielding one did. This, of course, raises a fundamental question concerning what work the notion of truth does for us. The chapter mounts a case for the claim that inflationists, but not obvious deflationists, about truth should offer a replacement for the concept of truth.

scholarly journals R-cadherin influences cell motility via Rho family GTPases. Vol. 279 (2004) 31041-31049

2004 ◽  
Vol 279 (42) ◽  
pp. 44229-44230
Author(s):  
Emhonta Johnson ◽  
Christopher S. Theisen ◽  
Keith R. Johnson ◽  
Margaret J. Wheelock
Keyword(s):  
Cell Motility ◽  
Rho Family Gtpases ◽  
Rho Family
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