Multiscale modeling of exocytosis in the fertilization process

TL;DR

This paper presents a multiscale biophysical-chemical model that accurately simulates exocytosis during fertilization, integrating calcium signaling, protein motor activity, and vesicle transport, validated against fluorescence data.

Contribution

It introduces a novel multiscale model linking calcium dynamics, cytoskeletal activity, and exocytosis, providing detailed spatio-temporal predictions validated by experiments.

Findings

Model accurately reproduces fluorescence measurements of exocytosis

Analyzes polyspermy block formation in sea urchin eggs

Integrates calcium signaling with cytoskeletal transport mechanisms

Abstract

We discuss the implementation of a multiscale biophysico-chemical model able to cope with the main mechanisms underlying cumulative exocytosis in cells. The model is based on a diffusion equation in the presence of external forces that links calcium signaling and the biochemistry associated to the activity of cytoskeletal-based protein motors. This multiscale model offers an excellent quantitative spatio-temporal description of the cumulative exocytosis measured by means of fluorescence experiments. We also review pre-existing models reported in the literature on calcium waves, protein motor activation and dynamics, and intracellular directed transport of vesicles. As an example of the proposed model, we analyze the formation of the shield against polyspermy in the early events of fertilization in sea urchin eggs.