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SUMMARY:A Spatial Stochastic Model of Cell Polarization - Linda Petzold (U
 niversity of California)
DTSTART:20160119T141500Z
DTEND:20160119T150000Z
UID:TALK64651@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Co-authors: Brian Drawert (UC Santa Barbara)\, Michael Lawson 
 (Uppsala University)\, Tau-Mu Yi (UC Santa Barbara)\, Mustafa Khammash (ET
 H Zurich)\, Otger Campas (UC Santa Barbara)\, Michael Trogdon (UC Santa Ba
 rbara)&nbsp\;AbstractPolarization is an essential behavior of living cells
 \, yet the dynamics of this symmetry-breaking process are not fully unders
 tood. Previously\, noise was thought to interfere with this process\; howe
 ver\, we show that stochastic dynamics plan an essential role in robust ce
 ll polarization and the dynamic response to changing cues.&nbsp\;<br><br>T
 o further our understanding of polarization\, we have developed a spatial 
 stochastic model of cellular polarization during mating of Saccharomyces c
 erevisiae. Specifically we investigate the ability of yeast cells to sense
  a spatial gradient of mating pheromone and respond by forming a projectio
 n in the direction of the mating partner. Our mechanistic model integrates
  three components of the polarization process: the G-protein cycle activat
 ed by pheromone bound receptors\, the focusing of a Cdc42 polarization cap
 \, and the formation of the tight localization of proteins on the membrane
  known as the polarisome.&nbsp\;<br><br>Our results demonstrate that highe
 r levels of stochastic noise result in increased robustness\, giving suppo
 rt to a cellular model where noise and spatial heterogeneity combine to ac
 hieve robust biological function. Additionally\, our simulations predict t
 hat two positive feedback loops are required to generate the spatial ampli
 fication to produce focal polarization. We combined our modeling with expe
 riments to explore the critical role of the polarisome scaffold protein Sp
 a2 during yeast mating\, and as a result\, have characterized a novel posi
 tive feedback loop critical to focal polarization via the stabilization of
  actin cables.&nbsp\;<br>
LOCATION:Seminar Room 1\, Newton Institute
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