BEGIN:VCALENDAR
VERSION:2.0
PRODID:icalendar-ruby
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VTIMEZONE
TZID:Europe/Vienna
BEGIN:DAYLIGHT
DTSTART:20200329T030000
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
TZNAME:CEST
END:DAYLIGHT
BEGIN:STANDARD
DTSTART:20191027T020000
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZNAME:CET
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTAMP:20260404T015830Z
UID:5e392fe705f54307655006@ist.ac.at
DTSTART:20200211T161500
DTEND:20200211T173000
DESCRIPTION:Speaker: Romain Levayer\nhosted by Edouard Hannezo\nAbstract: W
 hile the signals regulating apoptosis during development are rather well k
 nown\, what regulates the precise spatio-temporal distribution of cell dea
 th and the adjustment of cell elimination to local perturbations is not we
 ll understood. Using the Drosophila pupal notum (a single layer epithelium
 )\, we previously showed that cell extrusion and cell death could be modul
 ated by cell deformations. We recently showed that this is mediated by the
  activation of the pro-survival signal EGFR/ERK by cell stretching. Howeve
 r\, the exact contribution of the mechanical modulation of EGFR/ERK to nor
 mal development and morphogenesis was not known. By combining a live senso
 r of ERK\, segmentation and tracking\, we show that ERK is systematically 
 activated for 1 hour in the first row of cells surrounding each extruding 
 cell.  This transient activation correlates with the transient stretching 
 of the neighbouring cells and can be simulated by local ablation of a sing
 le cell. The pulse of ERK is sufficient to downregulate transiently caspas
 e activation in the neighbouring cells. Using statistical analysis and sim
 ulations\, we show that this feedback modulates the spatio-temporal distri
 bution of cell death by generating a transient death-refractory zone aroun
 d each dying cell. Finally\, using a novel optogenetic tool to trigger cas
 pase activation\, we show that simultaneous extrusion of 3 cells is suffic
 ient to perturb epithelial integrity. While such clusters are never observ
 ed in WT conditions\, they start to appear upon perturbation of ERK feedba
 ck and are associated with transient loss of impermeability. Altogether\, 
 this work suggest that the global distribution of cell elimination is an e
 mergent properties of local and transient feedbacks.In the second part\, I
  will present our recent attempt to characterize the process of cell extru
 sion in the pupal notum and the contribution of caspase to cell extrusion.
LOCATION:Mondi Seminar Room 3\, Central Building\, ISTA
ORGANIZER:channezo@ist.ac.at
SUMMARY:Romain Levayer: Fine tuning of cell death during epithelial homeost
 asis: from local coordination to death commitment and cell extrusion
URL:https://talks-calendar.ista.ac.at/events/2634
END:VEVENT
END:VCALENDAR