Retrograde BMP signaling and canonical pMad/Medea-mediated transcription regulates diverse target genes across subsets of Drosophila efferent neurons, to differentiate neuropeptidergic neurons and promote motor neuron terminal maturation. How a common BMP signal regulates diverse target genes across neuronal subsets remains largely unresolved, although available evidence implicates subset-specific transcription factor codes rather than differences in BMP signaling. Here, we examine the cis-regulatory mechanisms restricting BMP-induced FMRFa neuropeptide expression to Tv4 neurons. We find that pMad/Medea bind at an atypical, low affinity motif in the FMRFa enhancer. Converting this motif to high affinity caused ectopic enhancer activity and eliminated Tv4 neuron expression. In silico searches identified additional motif instances functional in other efferent neurons, implicating broader functions for this motif in BMP-dependent enhancer activity. Thus, differential interpretation of a common BMP signal, conferred by low affinity pMad/Medea binding motifs, can contribute to the specification of BMP target genes in efferent neuron subsets.
All data generated or analysed during this study are included in the manuscript and supporting files
- Douglas W Allan
- Douglas W Allan
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Oliver Hobert, Howard Hughes Medical Institute, Columbia University, United States
© 2020, Berndt et al.
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