Séminaire Vision algorithmique et biologique
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|Formation of morphogenetic gradients and boundaries during early development|
David Holcman (École normale supérieure)
17 mai 2006
In pluricellular organisms, positional information is necessary to all developmental processes. In the neuroepithelium, for example, positional information regulates the emplacement of territories, the place of borders between these territories, axonal guidance and synapse formation. We want to understand how positional information is generated and how cells respond to this information by the expression of developmental programs. It is well known that morphogens constitute a class of molecules inducing morphogenetic responses to cells and cell ensembles. The concept of morphogen is related to that of positional value, as the generation of morphological and physiological characteristics is function of position. We have developed a mathematical model for morphogenetic gradient formation. The novelty of this model takes its origin in the hypothesis that homeoproteins, a class of transcription factors with morphogenetic functions, traffic from cell to cell and regulate their own expression in a non-cell autonomous manner. We will discuss in particular how morphogens can generate various gradients. The mathematical model is applied to study boundary formation and stability between two adjacent morphogenetic regions.