The Xenopus doublesex-related gene Dmrt5 is required for olfactory placode neurogenesis

Abstract

The Dmrt (doublesex and mab-3 related transcription factor) genes encode a large family of evolutionarily conserved transcription factors whose function in sex specific differentiation has been well studied in all animal lineages. In vertebrates, their function is not restricted to the developing gonads. For example, Xenopus Dmrt4 is essential for neurogenesis in the olfactory system. Here we have isolated and characterized Xenopus Dmrt5 and found that it is coexpressed with Dmrt4 in the developing olfactory placodes. As Dmrt4, Dmrt5 is positively regulated in the ectoderm by neural inducers and negatively by proneural factors. Both Dmrt5 and Dmrt4 genes are also activated by the combined action of the transcription factor Otx2, broadly transcribed in the head ectoderm and of Notch signaling, activated in the anterior neural ridge. As for Dmrt4, knockdown of Dmrt5 impairs neurogenesis in the embryonic olfactory system and in neuralized animal caps. Conversely, its overexpression promotes neuronal differentiation in animal caps, a property that requires the conserved C-terminal DMA and DMB domains. We also found that the sea anenome Dmrt4/5 related gene NvDmrtb also induces neurogenesis in Xenopus animal caps and that conversely, its knockdown in Nematostella reduces elav-1 positive neurons. Together, our data identify Dmrt5 as a novel important regulator of neurogenesis whose function overlaps with that of Dmrt4 during Xenopus olfactory system development. They also suggest that Dmrt may have had a role in neurogenesis in the last common ancestor of cnidarians and bilaterians.

The Bilaterian Head Patterning Gene six3/6 Controls Aboral Domain Development in a Cnidarian

“…Injection of NvSix3/6 MO does not have a significant effect on the NvRFa expression (Figure 8B). NvDmrtB is a transcription factor that is expressed in individual cells in the aboral half of the gastrula and that is involved in neural development (Figure 8C; [84]). Individual cells expressing NvDmrtB are still present at the aboral pole of NvSix3/6 MO-injected gastrulae, but their number is reduced and they are restricted to a smaller aboral territory (Figure 8D).…”

Sex-Biased Expression of Young Genes in <b><i>Silurana (Xenopus) tropicalis</i></b>

“…table 2). In Xenopus , DMRT paralogs not only belong to the gene family responsible for sex determination but are also involved in developing the olfactory system [Huang et al, 2005;Parlier et al, 2013]. It would be interesting to test whether or not the sex-biased olfactory receptor paralogs are involved in sex-related chemical responses, since olfactory receptor genes are known to respond to sex pheromones [Nakagawa et al, 2005].…”

Dmrta1 regulates proneural gene expression downstream of Pax6 in the mammalian telencephalon

“…; Parlier et al . ) and that zebrafish Dmrta2 regulates neurogenesis in the telencephalon (Yoshizawa et al . ).…”