A dominant negative form of p63 is regulated by BMP4 and participates in Xenopus epidermis development

CELESTE TRÍBULO; MANUEL J. AYBAR; SARA S. SÁNCHEZ

Gran Meliá Hotel, Cancún, Mexico

Congreso; First Pan American Congress in Developmental Biology; 2007

SDB, SMBD, LASDB

The ectodermal cells have to decide between two possible fates: the cells in the ventral side follow an epidermal fate while dorsal cells adopt a neural fate. The ectoderm patterning has been suggested to be under the control of BMP4 that induces epidermal fate and inhibit the formation of neural tissue. However, target genes regulated by BMP4 and their roles during the specification of epidermis are less understood. p63, a member of the p53 gene family, is required for mammalian epidermal development. In Zebrafish, the DNp63 isoform is a direct target of BMP and is required for epidermal proliferation. In Xenopus, only a cDNA corresponding to mammal DNp63g has been identified and its role in development remains unknown. We analyzed the participation of DNp63 in Xenopus epidermal development and whether it is regulated by BMP4. First, the expression pattern of DNp63 was analyzed and compared with the expression of FoxD3 and Sox2. By neurula stage, the main expression of DNp63 is located in the epidermis and also is detected as a defined line in the limit between neural folds and epidermis. Then, we overexpressed a dominant negative form of BMP4 (CM-BMP4) in whole embryos and in animal caps. The decrease in BMP4 levels leaded to a lower expression of DNp63. Finally, gain of function experiments of DNp63 produced an increase of the epidermal marker XK81A and a decrease of the neural crest and neural plate markers FoxD3 and Sox2. Taken together, our results suggest that DNp63 participates in the regulation of ectodermal fates by promoting the epidermis specification under the control of BMP4.