Hox‐mediated regulation of doublesex sculpts sex‐specific abdomen morphology in Drosophila

Abstract

Background: Hox transcription factors are deeply conserved proteins that guide development through regulation of diverse target genes. Furthermore, alteration in Hox target cis-regulation has been proposed as a major mechanism of animal morphological evolution. Crucial to understanding how homeotic genes sculpt the developing body and contribute to the evolution of form is identification and characterization of regulatory targets. Because target specificity is achieved through physical or genetic interactions with cofactors or co-regulators, characterizing interactions between homeotic genes and regulatory partners is also critical. In Drosophila melanogaster, sexually dimorphic abdominal morphology results from sex-specific gene regulation mediated by the Hox protein Abdominal-B (Abd-B) and products of the sex-determination gene doublesex (dsx). Together these transcription factors regulate numerous sex-specific characters, including pigmentation, cuticle morphology, and abdominal segment number. Results: We show Dsx expression in the developing D. melanogaster pupal abdomen is spatiotemporally dynamic, correlating with segments that undergo sexually dimorphic morphogenesis. Furthermore, our genetic analyses show Dsx expression is Abd-B dependent. Conclusions: Doublesex and Abd-B are not only requisite co-regulators of sexually dimorphic abdominal morphology. We propose that dsx is itself a transcriptional target of Abd-B. These data present a testable hypothesis about the evolution of sexually dimorphic segment number in Diptera.

Drosophila Hox and Sex-Determination Genes Control Segment Elimination through EGFR and extramacrochetae Activity

“…This suggested that Abd-B may regulate dsx expression and, according with this assumption, we found that down-regulation of Abd-B reduces dsx expression (Figure 6T). Similar results have been reported recently [46]. Our experiments suggest that changes in DsxF or DsxM levels in the A7, dictated by Abd-B , may mediate Abd-B effects.…”

Neuroblast pattern and identity in the Drosophila tail region and role of doublesex in the survival of sex-specific precursors

“…Furthermore, it has been postulated that Abd-B sculpts sex-specific abdomen morphology by positively regulating dsx during pupal development (Wang and Yoder, 2012). Our data suggest that Abd-B participates in controlling survival of sex-specific abdominal NBs, but the mechanisms of its putative interaction with dsx and other factors still need to be clarified.…”

Sex- and Tissue-Specific Functions of Drosophila Doublesex Transcription Factor Target Genes

“…There is precedent for feedback in sex determination as TRA is a feedback regulator of Sxl (Siera and Cline, 2008). Similarly, predicted targets of DSX such as Sex combs reduced , Abdominal-B ( Abd-B ), and others encode transcription factors known to regulate dsx expression (Chatterjee et al, 2011; Devi and Shyamala, 2013; Tanaka et al, 2011; Wang and Yoder, 2012). Recently, micro-RNAs have been shown to modulate sex determination (Weng et al, 2013) suggesting we are far from understanding even the basic framework for sex determination and differentiation.…”

“…These cell types derive from all primary germ layers and have diverse roles in metabolism, gametogenesis, morphology, and behavior. While the transcriptional inputs to dsx expression are not fully understood, Drosophila HOX and other patterning genes regulate dsx in at least some tissues (Foronda et al, 2012; Tanaka et al, 2011; Wang et al, 2011; Wang and Yoder, 2012; Yoder, 2012). …”