Signal localization as a phase separation process

It is well known that ultrasensitivity (Goldbeter & Koshland, 1981) is the core of many bistable switches in biological systems. It is not as well recognized that when ultrasensitive self-amplifying circuits are diffusively coupled in a spatially distributed system such as the cell plasmamembrane, they may induce its dynamic separation into distinct signaling phases. This basic mechanism lays behind the process of cell membrane polarization in many, diverse biological systems. Cell membrane polarization is implicated in basic biological phenomena such as differentiation, proliferation, migration and morphogenesis of unicellular and multicellular organisms. Physical models based on the coupling of membrane diffusion with bistable enzymatic dynamics can reproduce a broad range of symmetry-breaking events, such as those observed in eukaryotic directional sensing, the apico-basal polarization of epithelial cells, the polarization of budding and mating yeast.

Date: 
Thu, 16/01/2014 - 14:30
Speaker: 
Andrea Gamba