Posterior axis formation requires Dlx5/Dlx6 expression at the neural plate border

Neural tube defects (NTDs), one of the most common birth defects in human, present a multifactorial etiology with a poorly defined genetic component. The Dlx5 and Dlx6 bigenic cluster encodes two evolutionary conserved homeodomain transcription factors, which are necessary for proper vertebrate development. It has been shown that Dlx5/6 genes are essential for anterior neural tube closure, however their role in the formation of the posterior structures has never been described. Here, we show that Dlx5/6 expression is required during vertebrate posterior axis formation. Dlx5 presents a similar expression pattern in neural plate border cells during posterior neurulation of zebrafish and mouse. Dlx5/6-inactivation in the mouse results in a phenotype reminiscent of NTDs characterized by open thoracic and lumbar vertebral arches and failure of epaxial muscle formation at the dorsal midline. The dlx5a/6a zebrafish morphants present posterior NTDs associated with abnormal delamination of neural crest cells showing altered expression of cell adhesion molecules and defects of motoneuronal development. Our findings provide new molecular leads to decipher the mechanisms of vertebrate posterior neurulation and might help to gather a better understanding of human congenital NTDs etiology.

Comparative analysis of molecular signatures suggests the use of gabapentin for the management of endometriosis-associated pain

Background

It has been repetitively shown that the transcription factors DLX5 and DLX6 are drastically downregulated in endometriotic lesions when compared with eutopic endometrium. These findings suggest that regulatory cascades involving DLX5/6 might be at the origin of endometriosis symptoms such as chronic pelvic pain (CPP). We have shown that inactivation of Dlx5 and Dlx5/6 in the mouse uterus results in an endometrial phenotype reminiscent of endometriosis.

Methods

We focused on genes that present a similar deregulation in endometriosis and in Dlx5/6-null mice in search of new endometriosis targets.

Results

We confirmed a strong reduction of DLX5 expression in endometriosis implants. We identified a signature of 30 genes similarly deregulated in human endometriosis implants and in Dlx5/6-null mouse uteri, reinforcing the notion that the downregulation of Dlx5/6 is an early event in the progress of endometriosis. CACNA2D3, a component of the α2δ family of voltage-dependent calcium channel complex, was strongly overexpressed both in mutant mouse uteri and in endometriosis implants, were also CACNA2D1 and CACNA2D2, other members of the α2δ family involved in nociception, are upregulated.

Conclusion

Comparative analysis of gene expression signatures from endometriosis and mouse models showed that calcium channel subunits α2δ involved in nociception can be targets for the treatment of endometriosis-associated pain. CACNA2D3 has been associated with pain sensitization and heat nociception in animal models. In patients, CACNA2D3 variants were associated with reduced sensitivity to acute noxious stimuli. As α2δs were targets of gabapentinoid analgesics, the results suggested the use of these drugs for the treatment of endometriosis-associated pain. Indeed, recent small-scale clinical studies have shown that gabapentin could be effective in women with CPP. The findings of this study reinforce the need for a large definitive trial.