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SUMMARY:Two Distinct Actin Networks Mediate Traction Oscillations to Confe
 r Mechanosensitivity of Focal Adhesions
DTSTART:20170711T110000
DTSTAMP:20260510T165131Z
UID:16af0b990dbb3b6da0ab789616afa8507e9d30d6b8534353c3ac374f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Jian Liu\, NIH\, Bethesda\, MD (USA)\nBIOENGINEERING SEM
 INAR\n\nAbstract:\nFocal adhesions (FAs) are integrin-based transmembrane 
 assemblies that connect the cell with its extracellular matrix (ECM). They
  are mechanosensors through which cells exert actin cytoskeleton-mediated 
 traction force to sense the ECM stiffness. Interestingly\, FA itself is a 
 dynamic structure that adapts its growth in response to mechanical force. 
 It is unclear how the cell manages the plasticity of FA structure and the 
 associated traction force to accurately sense ECM stiffness. Strikingly\, 
 FA traction forces oscillate in time and space and govern the cell mechano
 sensing of ECM stiffness. But precisely how and why the FA traction oscill
 ates is unknown. We develop a model of FA growth that integrates the contr
 ibutions of branched actin network and stress fibers (SF). Combining with 
 experimental testing\, we show that the retrograde flux of branched actin 
 network promotes the proximal growth of the FA\, and contributes to a trac
 tion peak near the FA distal tip. The resulting traction gradient within t
 he growing FA favors SF formation near the FA proximal end. The SF-mediate
 d actomyosin contractility further stabilizes the FA and generates a secon
 d traction peak near the FA center. Formin-mediated SF elongation negative
 ly feeds back with actomyosin contractility\, resulting in the central tra
 ction peak oscillation. This underpins the observed FA traction oscillatio
 n\, and importantly\, broadens the ECM stiffness range\, over which FAs co
 uld accurately adapt with traction force generation. Actin cytoskeleton-me
 diated FA growth and maturation thus culminate with FA traction oscillatio
 n to drive efficient FA mechanosensing.\n\nBio:\nJian Liu graduated from P
 eking University with a B.S. in chemistry in 2000 and earned his Ph.D. in 
 theoretical chemistry from the University of California\, Berkeley in 2005
 . He completed postdoctoral fellowships at the University of California\, 
 San Diego\, Center for Theoretical Biological Physics from 2005 to 2007 an
 d at the University of California\, Berkeley\, Department of Molecular and
  Cell Biology in the laboratory of George Oster from 2007 to 2009. Dr. Liu
  joined the NHLBI as a tenure-track Investigator in 2009. Dr. Liu’s labo
 ratory uses the tools of statistical physics to cohere this expanding data
  set from biological experiments into quantitative models that capture fun
 damental insights and make concrete predictions about multiple cellular pr
 ocesses\, including membrane trafficking\, cell motility\, and cell divisi
 on.
LOCATION:SV 1717 https://plan.epfl.ch/?room==SV%201717
STATUS:CONFIRMED
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