The pair-rule cross-regulatory module
Taxon: D. melanogaster
Process: Segmentation | Development
Submitter: D. Thieffry
Supporting paper: Sánchez, Lucas and Thieffry, Denis (2003). Segmenting the fly embryo: a logical analysis of the pair-rule cross-regulatory module. Journal of Theoretical Biology. 10.1016/s0022-5193(03)00201-7
| Model file(s) | Description(s) |
|---|---|
| pairRule.zginml | Pair-rule cross-regulatory module |
Summary:
This manuscript reports a dynamical analysis of the pair-rule cross-regulatory
module controlling segmentation in Drosophila melanogaster. We propose a
logical model accounting for the ability of the pair-rule module to determine
the formation of alternate juxtaposed Engrailed- and Wingless-expressing cells
that form the (para)segmental boundaries. This module has the intrinsic
capacity to generate four distinct expression states, each characterized by
the expression of a particular combination of pair-rule genes or expression
mode. The selection of one of these expression modes depends on the maternal
and gap inputs, but also crucially on cross-regulations among pair-rule genes.
The latter are instrumental in the interpretation of the maternal-gap pre-pattern.
Our logical model allows the qualitative reproduction of the patterns
of pair-rule gene expressions corresponding to the wild type situation, to
loss-of-function and cis-regulatory mutations, and to ectopic pair-rule
expressions. Furthermore, this model provides a formal explanation for the
morphogenetic role of the initial bell-shaped expression of the gene even-skipped,
i.e. for the distinct effects of different levels of the Even-skipped
protein on its target pair-rule genes. It also accounts for the requirement of
Even-skipped for the formation of all Engrailed-stripes. Finally, it provides
new insights into the roles and evolutionary origins of the apparent
redundancies in the regulatory architecture of the pair-rule module.