Interpretation of the UPD/JAK/STAT morphogen gradient in Drosophila follicle cells

 Abstract

We are using Drosophila follicle cells to study the mechanisms that promote cell motility.  Using genetics we identified a gene regulatory network that controls the dynamic pattern of activation of JAK/STAT in anterior follicle cells. Under the influence of a graded signal, Unpaired (UPD), JAK/STAT becomes activated first in a graded fashion.  STAT, in turn, locally activates its own repressor, Apontic (APT), a new feedback regulator of JAK/STAT signaling.  High levels of JAK/STAT also activate Slow Border Cells (SLBO), which undermines APT-mediated repression.  In this way, cells that achieve a high JAK/STAT level maintain SLBO expression and form border cells, which then migrate out of the cell layer.  Cells with lower JAK/STAT activity express more APT than SLBO, ultimately lose STAT activity, and remain in the follicular epithelium.  To better understand how the graded signal is converted to an all-or-none decision to move or stay, we developed a mathematical model.  Simulations using the model reproduce the observed dynamics of JAK/STAT expression in the wild type and in several mutant situations.  By combining biological experiments and mathematical modeling, we can achieve a more sophisticated understanding of how cells interpret molecular gradients.

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2918 - 2926
doi
10.4161/cc.8.18.9547
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Interpretation of the UPD/JAK/STAT morphogen gradient in Drosophila follicle cells