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UID:0-737@lptms.universite-paris-saclay.fr
DTSTART:20200421T110000Z
DTEND:20200421T120000Z
DTSTAMP:20200416T084655Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
 s-cecile-sykes-institut-curie/
SUMMARY:Séminaire du LPTMS: Cécile Sykes (Institut Curie) - Salle des sé
 minaires du FAST et du LPTMS\, bâtiment Pascal n°530 - 21 Avr 20 11:00
DESCRIPTION:Active deformation of the cell membrane through actin assembly\
 , and how we may infer nucleus deformation\nCécile Sykes (Institut Curie)
 \n\nZOOM MEETING ID: 919 2003 3856 - PASSWORD: 041219 -- \n\nIn all cell f
 unctions\, a common observation is that cytoskeleton assembly correlates w
 ith membrane deformation based on active forces. The exact role\, in parti
 cular\, of the actin cytoskeleton in cell membrane deformation\, with push
 ing or pulling forces\, is what we address both experimentally and theoret
 ically. We conceive stripped-down experimental systems that reproduce cell
 ular behaviours in simplified conditions: cytoskeleton dynamics are reprod
 uced on liposome membranes. Actin polymerization through the growth of a b
 ranched actin network is able to initiate membrane tubules and spikes by p
 ushing or pulling\, and mimics cellular deformations. By changing experime
 ntally membrane tension and the structural details of the cytoskeleton arc
 hitecture\, we displace the system within a phase diagram where inward or 
 outward deformations are favoured [1]. Moreover\, shells of branched actin
  networks grown around liposomes display buckling and wrinkling under osmo
 tic deflation\, thereby confirming their elastic properties. The time duri
 ng which we let the network grow around liposomes allows us to vary the sh
 ell thickness\, and to specify the length scale of buckling versus wrinkli
 ng [2]. Our results illustrate the generic mechanism of buckling and wrink
 ling found in various systems spanning from pollen grains to the developme
 nt of the gut or the brain.\n\nInspired by actin forces exerted on membran
 es and organelles\, we address now how the nucleus\, which is the most rig
 id cell organelle\, is deformed by the actin cytoskeleton during cell tran
 slocation. When cells move through narrow spaces that are smaller than the
 ir nuclei\, we find that proteins of the nuclear membrane\, such as nespri
 ns\, accumulate at the nucleus front and pull the nucleus forward [3]. We 
 want to address in the future how we could characterize this active proces
 s and infer its molecular details.\n\nReferences:\n[1] Simon et al.\, Natu
 re Physics (2019)\n[2] Kusters et al.\, Soft Matter (2019)\n[3] Davidson e
 t al.\, in revision
CATEGORIES:seminars
LOCATION:Salle des séminaires du FAST et du LPTMS\, bâtiment Pascal n°53
 0\, rue André Riviere\, Orsay\, 91405\, France
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=rue André Riviere\, Orsay\
 , 91405\, France;X-APPLE-RADIUS=100;X-TITLE=Salle des séminaires du FAST 
 et du LPTMS\, bâtiment Pascal n°530:geo:0,0
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