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.
Highlights
Biological processes frequently involve several mechanisms and sub-processes that link different temporal and length scales such as, for example, intracellular molecular interactions to the scale of cells and beyond to the behavior of collectives of cells and even organisms [1]
We aim to describe, link and use three theoretical models reported in the literature that allow to formulate a theoretical multiscale model able to cope, with high precision, with intracellular processes involving exocytosis, that is, with the process by which a cell directs the contents of secretory vesicles out of the cell membrane and into the extracellular space
A calcium wave occurs in the presence of inhibitors against inositol triphosphate receptors (IP3R s) or ryanodine receptors (RyR’s) but not when both inhibitor types are used, suggesting that the two receptors may redundantly participate during fertilization [51]
Summary
Biological processes frequently involve several mechanisms and sub-processes that link different temporal and length scales such as, for example, intracellular molecular interactions to the scale of cells and beyond to the behavior of collectives of cells and even organisms [1]. Simple theoretical models able to cope with these problems are less developed in the literature, they may be of great importance because they can simplify the quantitative description without loss of accuracy and, more important, by allowing to give clear interpretations of the different mechanisms in terms of simple and well understood physicochemical laws In this short review, we aim to describe, link and use three theoretical models reported in the literature that allow to formulate a theoretical multiscale model able to cope, with high precision, with intracellular processes involving exocytosis, that is, with the process by which a cell directs the contents of secretory vesicles out of the cell membrane and into the extracellular space. We will study the case of the early events of fertilization, that is, the formation of the shield against polyspermy in oocytes (Figure 1)
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