Fig. 9: The domain-specific activation of Dfd target genes in the maxillary segment relies on the balance between its concentration and binding affinity. | Nature Communications

Fig. 9: The domain-specific activation of Dfd target genes in the maxillary segment relies on the balance between its concentration and binding affinity.

From: Specificity of the Hox member Deformed is determined by transcription factor levels and binding site affinities

Fig. 9

In wild-type embryos, AP-2 is activated in the posterior maxillary border cells with high Dfd levels (HIGHDfd), enabling Dfd–Exd complexes to bind and activate the AP-2 via the maxillary AP2x-377 enhancer. In the remaining regions of the maxillary segment, Dfd is expressed at lower concentrations (LOWDfd) and is unable to activate AP2x-377. Optimization of Dfd–Exd sites in AP2x-377 (AP2x-377optimal) results in an increase in Dfd–Exd binding affinity, which allows activation of AP2x-377optimal in the anterior and ventral regions of the maxillary segment. Co-factors of Dfd involved in the activation of the AP2x-377 are present throughout the maxillary segment with the concentration and binding affinity of Dfd–Exd determining the domain-specific activation of AP2x-377. Primordia of Dfd-regulated maxillary structures: ventral organ (green area); dorsal cirri (yellow area); ventral cirri (pink area); mouth hooks (blue area). The grey area in the mandibular and maxillary segments (outlined by dash lines) indicates the area of Dfd expression. The dotted lines in the maxillary segment indicate the posterior border cells with high Dfd levels. Md Mandibular segment, Mx Maxillary segment, Lb Labial segment.

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