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SUMMARY:Marc Trani Bustos: Building the mammalian embryo body: tissue surf
 ace mechanics constrains proliferation-driven forces to guide axial elonga
 tion\; Denis Krndija-“Cracking” the Gut Epithelium: How Goblet Cells M
 echanically Disrupt the Gut Barrier. - Marc Trani Bustos\, Denis Krndija
DTSTART:20260223T143000Z
DTEND:20260223T153000Z
UID:TALK241603@talks.cam.ac.uk
CONTACT:Jia CHEN
DESCRIPTION:Name:  Marc Trani Bustos \n\nAffiliation: Max Planck Institute
  for Cell Biology and Genetics\, Dresden\, Germany \n\nTitle: Building the
  mammalian embryo body: tissue surface mechanics constrains proliferation-
 driven forces to guide axial elongation. \n\nAbstract:\nMammalian embryos 
 undergo complex morphogenetic changes after implantation in the uterus. Th
 e elongation of the body along a head-to-tail axis is a pivotal event\, as
  it lays the foundation of the body plan. While genetic and biochemical as
 pects of mammalian body elongation have been uncovered\, the physical mech
 anism of axial morphogenesis remains unknown\, largely due to the inaccess
 ibility of the implanted embryo to physical measurements and manipulations
  in utero. Gastruloids\, a stem-cell-based embryo model of mammalian axial
  morphogenesis\, lift such limitations. Combining live imaging\, direct me
 chanical measurements\, and chemical and mechanical perturbations\, here w
 e show that axis elongation in mouse and human gastruloids is guided by a 
 posterior ‘actin cap’ at the tissue surface that constrains the expans
 ive forces of cell proliferation. Measurements of mechanical stresses usin
 g oil microdroplets\, as well as inhibition of cell proliferation and myos
 in activity\, show that the forces driving elongation arise from cell prol
 iferation\, and not from convergent extension movements. We find that isot
 ropic tissue expansion is re-directed into posterior elongation by the for
 mation of a supracellular actin cap at the posterior tissue surface that r
 estricts lateral tissue expansion. Finally\, we show that posterior elonga
 tion in mouse embryos displays the key features of the physical elongation
  mechanism reported for mouse and human gastruloids. These findings reveal
  that mammalian body axis elongation\, including human\, occurs via a diff
 erent physical mechanism from other vertebrate species.    \n\nPreprint:
  https://doi.org/10.1101/2025.10.27.684710  \n\nDenis Krndija\n\nAffiliati
 on: Group Leader (ATIP-Avenir)\, Centre for Integrative Biology (CBI)\, Mo
 lecular\, Cellular and Developmental Biology (MCD)\, France\n\nTitle: “C
 racking” the Gut Epithelium: How Goblet Cells Mechanically Disrupt the G
 ut Barrier\n\nAbstract:\nThe intestinal epithelium\, one of the largest ep
 ithelial surfaces\, has to maintain a tight barrier against the harsh lumi
 nal environment. Barrier integrity primarily depends on cell-cell junction
 s formed by enterocytes\, absorptive cells characterised by their polygona
 l and columnar morphology. In contrast\, mucus-producing goblet cells\, wh
 ich are interspersed among enterocytes\, exhibit a rounded apical cell sha
 pe and a voluminous body – raising the question of how epithelial integr
 ity is maintained among cells with such different morphologies. Here\, we 
 show that goblet cells mechanically induce tight junction fractures betwee
 n neighbouring enterocytes under homeostatic conditions in vivo\, and that
  this effect is exacerbated during goblet cell hypertrophy\, leading to in
 creased gut permeability. Using a combination of in vivo (mouse) and organ
 oid models\, along with pharmacological\, genetic and mechanical perturbat
 ions\, as well as theoretical modelling\, we demonstrate that these fractu
 res arise from a force imbalance at cell interfaces: goblet cells exert co
 mpressive forces that deform adjacent enterocytes\, whose junctions ruptur
 e depending on tissue rheology controlled by myosin II. Together\, our fin
 dings uncover a previously unrecognised mechanical role of goblet cells in
  destabilising epithelial cohesion and establish cell type heterogeneity a
 nd intercellular force balance as critical determinants of junctional inte
 grity and gut barrier function.\n\n
LOCATION:Online
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