The Non-Proliferative Nature of Ascidian Folliculogenesis as a Model of Highly Ordered Cellular Topology Distinct from Proliferative Epithelia

Karim Azzag (1) , Yoann Chélin (2, 3) , Francois Rousset (1) , Emilie Le Goff (1) , Camille Martinand-Mari (1) , Anne-Marie Martinez (4) , Bernard Maurin (2, 3) , Martine Daujat-Chavanieu (5) , Nelly Godefroy (1) , Julien Averseng (2, 3) , Paul Mangeat (6) , Stephen Baghdiguian (1)

1 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier
2 LMGC - Laboratoire de Mécanique et Génie Civil
3 SIGECO - Structures Innovantes, Géomatériaux, ECOconstruction
4 IGH - Institut de génétique humaine
5 Cellules Souches, Plasticité Cellulaire, Médecine Régénératrice et Immunothérapies (IRMB)
6 CRBM - Centre de recherche en Biologie cellulaire de Montpellier

Previous studies have addressed why and how mono‐stratified epithelia adopt a polygonal topology. One major additional, and yet unanswered question is how the frequency of different cell shapes is achieved and whether the same distribution applies between non-prolifer-ative and proliferative epithelia. We compared different proliferative and non-proliferative epithelia from a range of organisms as well as Drosophila melanogaster mutants, deficient for apoptosis or hyperproliferative. We show that the distribution of cell shapes in non‐prolif-erative epithelia (follicular cells of five species of tunicates) is distinctly, and more stringently organized than proliferative ones (cultured epithelial cells and Drosophila melanogaster imaginal discs). The discrepancy is not supported by geometrical constraints (spherical versus flat monolayers), number of cells, or apoptosis events. We have developed a theoretical model of epithelial morphogenesis, based on the physics of divided media, that takes into account biological parameters such as cell‐cell contact adhesions and tensions, cell and tissue growth, and which reproduces the effects of proliferation by increasing the topological heterogeneity observed experimentally. We therefore present a model for the morphogene-sis of epithelia where, in a proliferative context, an extended distribution of cell shapes (range of 4 to 10 neighbors per cell) contrasts with the narrower range of 5-7 neighbors per cell that characterizes non proliferative epithelia.

Domaines: Biomécanique [physics.med-ph]

Karim Azzag, Yoann Chélin, Francois Rousset, Emilie Le Goff, Camille Martinand-Mari, et al.. The Non-Proliferative Nature of Ascidian Folliculogenesis as a Model of Highly Ordered Cellular Topology Distinct from Proliferative Epithelia. PLoS ONE, 2015, 10 (5), ⟨10.1371/journal.pone.0126341⟩. ⟨hal-01772603⟩