Model of Autocrine/Paracrine Signaling in Epithelial Layer

An autocrine/paracrine signaling model in epithelial layers is described. The axially symmetric model of the epithelial layer explicitly considers the microvilli of the epithelial cells and the gaps between nearest neighbor microvilli. Ligand trapping site distribution functions and probability of autocrine signaling are calculated for different epithelial geometries and ligand sources by numerically solving the inhomogeneous stationary diffusion equation, the Poisson equation. In general, the global characteristics of the trapping site distribution curves are similar to the ones obtained for a planar epithelial model, and the superimposed small periodical changes of the curves reflect the details of the epithelial geometry. However, when ligands are emitted into a narrow gap between nearest neighbor microvilli the probability of local trapping is particularly high, causing a locally large deviation from the overall behavior of the trapping site distribution curves. If the microvilli of the cell are closely packed, then the probability of paracrine signaling is about 0.2. However, this probability jumps to about 0.5 if the cell is able to slightly loosen the tight packing, for example, by decreasing the diameter of the microvilli by only 2%. On the basis of our calculations, alteration of microvillus geometry represents a mechanism by which epithelial cells can efficiently regulate intercellular signaling. (Model of Autocrine/Paracrine Signaling in Epithelial Layer: Geometrical Regulation of Intercellular Communication, Sugár, István P., and Sealfon Stuart C. , J. Phys. Chem. B, 113(31), p.10946 - 10956, (2009))