Membrane growth induces neuronal bipolarity

MENCHÓN, SILVIA ADRIANA; GÄRTNER, ANNETTE; ROMÁN, PABLO; DOTTI, CARLOS

Congreso; BioMath; 2011

The generation and maintenance of asymmetric changes in cellular organization, (polarity), are very important for many complex biological activities. Neurons are among the cell types with the most prominent asymmetry. Neuronal polarization starts with the selection of the site from which the first neurite will grow before morphological changes are evident. It happens shortly after cell division and it is followed by the growth of a second neurite at the opposite pole. The site from which the first neurite emerges is defined by the localized accumulation or activation of molecules with the capacity to directly or indirectly induce a local deformation in the plasma membrane. However, it is not known if a direct relationship exists between the formation of the second, opposite, neurite and the mechanisms involved in the formation of the first. We tackled this issue through mathematical modeling, based on membrane traffic (exocytosis-endocytosis), and lateral diffusion. Our model assumes an activator-inhibitor dynamics and diffusion-driven instabilities. We study spontaneous symmetry breaking and how polarity domains are affected by membrane growth. With this approach, we demonstrated that a single pole of molecular asymmetry is sufficient to induce a second one at the opposite side, upon induction of growth from the first pole.