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SUMMARY:Actin cortex mechanics in animal cell morphogenesis - Prof Ewa Pal
 uch. MRC LMCB\, University College London
DTSTART:20130523T150000Z
DTEND:20130523T160000Z
UID:TALK41623@talks.cam.ac.uk
CONTACT:Annabel Griffiths
DESCRIPTION:The shape of animal cells is primarily determined by the cellu
 lar cortex\, a thin network of actin filaments and myosin motors that lies
  directly underneath the plasma membrane. The cortex enables the cell to r
 esist external stresses\, and generates the forces that allow cells to mov
 e and deform. We investigate how the mechanical properties of the cortex a
 rise from the microscopic architecture of the network\, and how controlled
  changes in these properties drive cell deformation. I will mostly focus o
 n cortex mechanics during cytokinesis\, a process directly driven by chang
 es in cortex organisation. At anaphase onset\, the cortex accumulates into
  an equatorial ring that drives furrow ingression. Although most studies o
 f cytokinetic mechanics focus on force generation at the constriction ring
 \, a contractile actomyosin cortex remains at the poles of dividing cells 
 throughout cytokinesis. Using a combination of experiments and theory\, we
  showed that the polar cortex makes cytokinesis an inherently unstable pro
 cess\, where any imbalance in contractile forces between the two poles can
  compromise the accurate positioning of the constriction ring. A theoretic
 al model based on a competition between cortex turnover and contraction dy
 namics accurately accounts for the oscillations. Taken together\, our find
 ings reveal an inherent instability in the shape of the dividing cell\, in
 dicating that polar cortex contractility must be tightly controlled to ens
 ure successful cytokinesis. When this control fails\, the cortex displays 
 oscillatory instabilities. Similar contractile instabilities might be invo
 lved in asymmetric division and in epithelial morphogenesis.
LOCATION:Hodgkin Huxley Seminar Room\, Physiology Building\, Downing Site
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