Modelling membrane-bound cellular organelles with non-equilibrium dynamics

Caption: Quantitative model of Golgi self-organisation between a source (the endoplasmic reticulum – E.R. – left, blue) and an exit (e.g. the Trans Golgi Network – right, green). The source emits immature vesicles (blue). Larger compartments are formed through homotypic fusion and vesicular budding. A steady-state is obtained when the in-flux is balanced by the out-flux.

Membrane-bound cellular organelles along the secretory and endocytic pathways perform essential functions, among which the sorting and biochemical maturation of cellular components. Understanding how the different molecular mechanisms controlling these processes are orchestrated to yield robust fluxes of matter and to direct particular components to particular locations within the cell is an outstanding problem for cell biologist, but also for physicists.

We build conceptual models of organelle biogenesis and maintenance that include vesicular exchange (budding, transport, and fusion) and biochemical maturation, i.e. the change of identity of an organelle over time (early to late endosomes, cis to trans Golgi cisternae…). Our model illuminates the intimate link between the structure and dynamics of the organelles.