Simulated distributions of the density of cell adhesion molecules over branching processes with different geometry and intracellular trafficking

Abstract

Adhesive cell-cell and cell-substrate interactions mediated by different types of cell adhesion molecules (CAM) are important for growth and migration processes. In simulation study we investigated the impact of geometry of branching cellular processes on the lateral distribution of CAM due to retrograde lateral diffusion from a growing part, where they were delivered by different assumed types of trafficking. The model incorporates trafficking of CAM to and installation in the growing active part of the cell, their lateral diffusive redistribution, formation and dissociation of CAM/ligand complexes, and CAM internalization by endocytosis. Since the rate of growth is two and one order(s) of magnitude slower than the rate of trafficking and lateral diffusion, respectively, steady state distributions of CAM were considered. Three possible types of intracellular CAM partitioning between sister branches were considered: equal, proportional to the branch cross-section area, and proportional to the branch surface area. Asymmetry of branching led to various inhomogeneous distributions of the CAM surface density along the branches, and these distributions depended on the type of intracellular trafficking, which might provide a basis for different modes of growth. One can speculate that, depending on these modes, initially asymmetrical branching can be either reinforced or symmetrized during further development.