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TZID:Europe/Paris
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BEGIN:VEVENT
UID:0-624@lptms.universite-paris-saclay.fr
DTSTART:20181003T110000Z
DTEND:20181003T120000Z
DTSTAMP:20180925T101123Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-alexis-lomakin/
SUMMARY:Physics-Biology interface seminar: Alexis Lomakin - Amphi BLANDIN d
 u LPS de la Faculté des Sciences d’Orsay (Bâtiment 510) - 3 Oct 18 11:
 00
DESCRIPTION:How do cells measure their boundaries to tailor physiological r
 esponses?\nAlexis Lomakin (King's College London\, UK)\n\nMuch like modern
  day engineered devices\, cells in the human body are able to make precise
  measurements: intestinal epithelial cells monitor local cell densities to
  prevent hyperplasia\, neutrophils sample their microenvironment to comput
 e the fastest migratory route toward infection sites\, and epidermal stem 
 cells use extracellular matrix occupancy to make cell fate decisions. What
  these examples illustrate is the sensitivity of complex cell behaviors to
  spatial and mechanical constraints\, known in quantitative sciences as bo
 undary conditions. Although the importance of boundary conditions in cell 
 and tissue physiology is increasingly recognized\, it remains unclear how 
 cells sample their boundaries to tailor specific behaviors to boundary con
 ditions. Here\, using biophysical tools to manipulate cell boundaries in a
  highly controlled\, quantitative manner\, we found that cells estimate ex
 ternally-imposed confinement using their largest and stiffest intracellula
 r component\, the nucleus. Cell confinement below a certain threshold defo
 rms the nucleus and expands its envelope area. Unbuffered against area exp
 ansion due to slow turnover of constituents\, the nuclear envelope becomes
  stretched. This in turn engages signaling via nuclear membrane stretch-se
 nsitive proteins to the actomyosin cortex\, activating contractility. The 
 latter provides a motive force for the cell to squeeze through tight pores
  and constrictions in the extracellular matrix. Interestingly\, no increas
 e in cell contractility is observed when cells move through environmental 
 confines that do not significantly deform the nucleus. Thus\, the nucleus 
 acts as an internal ruler for environmental confinement size\, allowing ce
 lls to utilize energetically costly contractility on demand\, only when su
 rrounding space becomes restrictive. The advantage of the proposed mechani
 sm is that in contrast to the plasma membrane\, nuclear membranes do not p
 articipate in constitutive membrane trafficking\; their surface area thus 
 fluctuates less. This intrinsic quiescence should privilege them to functi
 on as low-noise detectors\, to readily discriminate local environmental co
 nditions from internal traffic-induced cell area/tension fluctuations.\n
CATEGORIES:physbio,seminars
LOCATION:Amphi BLANDIN du LPS de la Faculté des Sciences d’Orsay (Bâtim
 ent 510)\, 15 Rue Georges Clemenceau\, orsay\, France
GEO:48.698187;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=Amphi BLANDIN du LPS de la Facu
 lté des Sciences d’Orsay (Bâtiment 510):geo:48.698187,2.181768
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