Jean-Jacques Kupiec est l’auteur du chapitre intitulé :« Cell differentiation is a stochastic process subjected to natural selection »
Abstract and Keywords
In contrast to classical determinist theories of development, an accumulation of data obtained over the last 30 years shows that gene expression is a stochastic phenomenon. Since gene expression is a basic step in the expression of a genetic program, this is a major discovery, the consequences of which could be crucial for understanding development. The chapter reviews the data as well as the mechanisms causing stochastic gene expression (SGE) and shows that it creates the diversity of gene expression patterns needed during cell differentiation. A model of cell differentiation based on SGE is proposed. In this model, cell differentiation is a two-sided mechanism at each stage of development. On the one hand, gene expression is stochastic and produces a diversity of gene expression patterns in differentiating cell populations. On the other hand, gene expression is stabilized in differentiated cells by means of cellular interactions. SGE is caused by random molecular interactions between chromatin proteins and DNA making chromatin dynamic stochastic, whereas epigenetic chromatin modifications triggered by signal transduction between cells are responsible for the stabilization of SGE. This model underlies a new theory in which ontogenesis results from an extension of natural selection working inside embryonic cell populations.
Keywords: cell differentiation, determinism, development, evolution, natural selection, probabilism, stochastic gene expression