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UID:1-384@lptms.universite-paris-saclay.fr
DTSTART:20151005T110000Z
DTEND:20151005T120000Z
DTSTAMP:20151001T061444Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-christophe-le-clainche/
SUMMARY:Physics-Biology interface seminar: Christophe Le Clainche - Moyen A
 mphi\, Building 510\, Université Paris-Saclay Orsay - 5 Oct 15 11:00
DESCRIPTION:Regulation of actin assembly and mechanotransduction in cell-ma
 trix adhesion complexes: a biochemical study of the talin-vinculin complex
 \nChristophe Le Clainche (I2BC\, Gif-sur-Yvette)\nCell migration is involv
 ed in many physiological and pathological processes. Force is produced by 
 the growth and the contraction of the actin cytoskeleton (1). To produce f
 orce in adherent cells\, these actin networks must be anchored to the extr
 acellular matrix (ECM) by adhesion complexes (1\,2). These structures cont
 ain transmembrane integrins that mechanically couple the ECM to the intrac
 ellular actin cytoskeleton via actin binding proteins (ABPs) (2). This sys
 tem acts as a molecular clutch that controls force transmission across adh
 esion complexes. This molecular clutch is a complex interface made of mult
 iple layers of regulated protein-protein interactions (2). The multiple ac
 tivities of the ABPs present in these structures play a critical role in t
 he dynamics of this interface. In addition to the control of actin filamen
 t binding and polymerization (1-3)\, these proteins sense and respond to t
 he force applied by the actomyosin cytoskeleton to adjust the anchoring st
 rength (4\,5). Our goal is to determine the molecular mechanisms by which 
 these ABPs cooperate to control the mechanical coupling between the actin 
 cytoskeleton and cell-matrix adhesion complexes.\n\nTo study these ABPs\, 
 our laboratory combines the measurement of actin polymerisation kinetics i
 n fluorescence spectroscopy\, single actin filament observations in TIRF m
 icroscopy and the reconstitution of actin-based mechanosensitive processes
  on micropatterned surfaces. Our model system is the mechanosensitive comp
 lex made of the two ABPs talin and vinculin.\nOur results showed that vinc
 ulin controls actin filament elongation (3). More recent results revealed 
 that talin also regulates actin polymerisation in response to integrin bin
 ding (unpublished data). In addition\, we have developed a microscopy assa
 y with pure proteins in which the self-assembly of actomyosin cables contr
 ols the association of vinculin to a talin-micropatterned surface in a rev
 ersible manner (4\, 5). This in vitro reconstitution revealed the mechanis
 m by which a key mechanosensitive molecular switch senses and controls the
  connection between adhesion complexes and the actomyosin cytoskeleton.\n\
 nReferences\n\n	(1) Christophe Le Clainche and Marie-France Carlier.\nReg
 ulation of actin assembly associated with protrusion and adhesion in cell 
 migration.\nPhysiological Reviews (2008) Apr\;88(2):489-513.\n	(2) Corina 
 Ciobanasu\, Bruno Faivre\, Christophe Le Clainche.\nIntegrating actin dyna
 mics\, mechanotransduction and integrin activation: The multiple functions
  of actin binding proteins in focal adhesions.\nEuropean Journal of Cell B
 iology (2013) (92) 339-348.\n	(3) Christophe Le Clainche\, Satya P Dwivedi
 \, Dominique Didry\, Marie-France Carlier.\nVinculin is a dually regulated
  actin filament barbed-end capping and side-binding protein.\nJournal of B
 iological Chemistry (2010) Jul 23\;285(30):23420-32.\n	(4) Corina Ciobanas
 u\, Bruno Faivre\, Christophe Le Clainche.\nActomyosin dependent formation
  of the mechanosensitive talin-vinculin complex reinforces actin anchoring
 .\nNature Communications (2014) 5:3095\n	(5) Corina Ciobanasu\, Bruno Faiv
 re\, Christophe Le Clainche.\nReconstituting actomyosin-dependent mechanos
 ensitive protein complexes in vitro.\nNature Protocols (2015) Jan \;10(1):
 75-89\n
CATEGORIES:physbio,seminars
LOCATION:Moyen Amphi\, Building 510\, Université Paris-Saclay Orsay\, 15 R
 ue Georges Clemenceau\, orsay\, France
GEO:48.698187;2.181768
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  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=Moyen Amphi\, Building 510\, Un
 iversité Paris-Saclay Orsay:geo:48.698187,2.181768
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