EGL-5/ABD-B plays an instructive role in male cell fate determination in the C. elegans somatic gonad

Abstract

Hox genes of the Abdominal-B (Abd-B) class regulate gonadal development in diverse metazoans. Here we have investigated the role of the Abd-B homolog egl-5 in C. elegans gonadal development. Previous work showed that egl-5 is required male-specifically in the gonad and that mutant gonads are highly dysgenic and possibly feminized. We have used sex-specific gonadal reporter genes to confirm that the gonads of egl-5 males are extensively feminized. Sex-specific expression of egl-5 requires the global sex determination gene tra-1 and the gonadal masculinizing gene fkh-6, but mutagenesis of a short male gonadal enhancer element in egl-5 suggested that this regulation is indirect. Ectopic expression of EGL-5 in hermaphrodites is sufficient to induce male gonadal gene expression, indicating that EGL-5 plays an instructive role in male gonadal fate determination. EGL-5 acts in parallel with a Wnt/β -catenin pathway to regulate male gonadal fates and can physically interact with the Wnt pathway transcription factor POP-1 and modulate activity of a POP-1 dependent reporter gene. We propose that EGL-5 imparts sex-specific function on POP-1 by recruiting it to male-specific gonadal target genes.

Cell-Specific mRNA Profiling of the Caenorhabditis elegans Somatic Gonadal Precursor Cells Identifies Suites of Sex-Biased and Gonad-Enriched Transcripts

“…Likewise, transcriptome analysis found that fkh-6 mRNA is gonad-enriched in both sexes at the earlier time, and at the later time it is gonad-enriched only in males. Additionally, reporters of egl-5 and hlh-3 were previously shown to be expressed in the late L1 gonad, exclusively in males ( Kalis et al 2010 ; J. Kimble, personal communication).…”

Sex and the singular DM domain: insights into sexual regulation, evolution and plasticity

“…Further work will be needed to establish the mechanism of this apparent sex change, its relevance to natural sex change in fish, and its similarity to the process in Dmrt1 mutant mice. Plasticity of gonadal sex also exists in C. elegans , although it may not involve DM domain genes: ectopic expression of egl-5 in XX hermaphrodites can induce male gene expression in the somatic gonad long after gonadal sex determination 75 . In mice, genetic studies are needed to understand which of the fetal sex-regulatory genes are postnatally redeployed for sex maintenance and to find genes that are specifically involved in sex maintenance.…”

Non‐transcriptional interactions of Hox proteins: Inventory, facts, and future directions

“…Downstream BMP signaling, for example, Hox proteins from distinct paralogy groups can interact with R‐Smad, Co‐Smad, or I‐Smad (Bai et al, ; Yang et al, ; Shi et al, ; Williams et al, ; Li et al, ; Wang et al, ; Quere et al, ). Downstream the Wnt/beta‐catenin signaling, EGL‐5, the Abdominal‐B homologue in Caenorhabditis elegans , interacts with POP‐1/TCF (Kalis et al, ). In relation to Hedgehog signaling, Hoxd12 and possibly other Hoxd proteins interact with Gli3 (Chen et al, ).…”