Geoffroea decorticans fruit extracts inhibit the wnt/β-catenin pathway, a therapeutic target in cancer

Geoffroea decorticans (chañar) is commonly used for culinary and medicinal purposes in rural communities. The aim of this work was to chemically characterize three Geoffroea decorticans extracts and determine their capacity to modulate the wnt/β-catenin pathway. This signaling pathway plays a key role in embryonic development but its overactivation leads to cancer cell growth. Phytochemical analysis of extracts showed presence of major classes of phytochemicals. Gas chromatography-mass spectrometry results revealed the presence of acids, esters and furanic compounds. Using Xenopus embryos as in vivo model organisms, we found that the extracts modulated dorso-ventral axis formation and rescued hyperdorsalized phenotypes produced by LiCl treatment. In agreement with these findings, Geoffroea decorticans extracts decreased β-catenin levels and suppressed the expression of wnt target genes such as xnr3 and chordin, thus demonstrating an inhibitory regulation of the wnt/β-catenin signaling pathway. All these results support a new role for Geoffroea decorticans fruit derivatives with possible anti-carcinogenic actions.

Gli2 is required for the induction and migration of Xenopus laevis neural crest

The neural crest (NC) is a multipotent migratory embryonic population that is formed during late gastrulation and gives rise to a wide array of derivatives, including cells from the peripheral nervous system (PNS), the craniofacial bones and cartilages, peripheral glial cells, and melanocyte cells, among others. In this work we analyzed the role of the Hedgehog signaling pathway effector gli2 in Xenopus NC. We provide evidence that the gli2 gene is expressed in the prospective, premigratory and migratory NC. The use of a specific morpholino against gli2 and the pharmacological specific inhibitor GANT61 in different experimental approaches allowed us to determine that gli2 is required for the induction and specification of NC cells as a transcriptional activator. Moreover, gli2 also acts by reducing apoptosis in the NC without affecting its cell proliferation status. We also demonstrated that gli2 is required cell-autonomously for NC migration, and for the formation of NC derivatives such as the craniofacial cartilages, melanocytes and the cranial ganglia. Altogether, our results showed that gli2 is a key transcriptional activator to accomplish the proper specification and development of Xenopus NC cells.

A balance between the anti-apoptotic activity of Slug and the apoptotic activity of msx1 is required for the proper development of the neural crest

We have studied the pattern of programmed cell death in the neural crest and analyzed how it is controlled by the activity of the transcription factors Slug and msx1. Our results indicate that apoptosis is more prevalent in the neural folds than in the rest of the neural ectoderm. Through gain- and loss-of-function experiments with inducible forms of both Slug and msx1 genes, we showed that Slug acts as an anti-apoptotic factor whereas msx1 promotes cell death, either in the neural folds of the whole embryos, in isolated or induced neural crest and in animal cap assays. The protective effect of expressing Slug can be reversed by expressing the apoptotic factor Bax, while the apoptosis promoted by msx1 can be abolished by expressing the Xenopus homologue of Bcl2 (XR11). Furthermore, we show that Slug and msx1 control the transcription of XR11 and several caspases required for programmed cell death. In addition, expression of Bax or Bcl2, produced similar effects on the survival of the neural crest and on the development of its derivatives to those produced by altering the activity of Slug or msx1. Finally, we show that in the neural crest, the region of the neural folds where Slug is expressed, cells undergo less apoptosis, than in the region where the msx1 gene is expressed, which correspond to cells adjacent to the neural crest. We show that the expression of Slug and msx1 controls cell death in certain areas of the neural folds, and we discuss how this equilibrium is necessary to generate sharp boundaries in the neural crest territory, and to precisely control cell number among neural crest derivatives.