A dominant negative form of p63 participate in the control of neural crest apoptosis in Xenopus laevis

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

Guarujá, Brasil

Congreso; Second International Meeting of the Latinamerican Society of Developmental Biology; 2005

Latin American Society of Developmental Biology (LASDB)

The p63 gene, a member of the p53 gene family, is structurally conserved among a wide range of organisms. In mammals, p63 has two promoters that generate two types of protein isoforms, TAp63 and DNp63. The TA isoforms are similar to p53 in that they are able to activate transcription of specific target genes and induce apoptosis. The DN isoforms lack the NH2-terminal transactivation domain and can function as ¡§dominant negative¡¨ proteins, blocking the function of the corresponding full-length proteins. The DN isoforms, therefore, have an anti-apoptotic role. In Xenopus, only a cDNA corresponding to mammalian DNp63g has been cloned and its role in development and apoptosis remains unknown. Previously, we determined that in Xenopus, apoptosis is localized in the neural crest region, and that during neural crest development BMP4 and msx1 promote apoptosis while Slug acts as an antiapoptotic gene. The purpose of the present study was to determine whether DNp63 participates in the regulation of apoptosis in the neural crest. The expression pattern of DNp63 was examined using whole mount in situ hybridization and compared with Slug and msx1 expression patterns. By neurula stage, DNp63 is detected in the external border of the neural crest territory. In order to elucidate whether p63 was able to modify the neural crest apoptosis we proceeded to overexpress DNp63 in whole embryos and in animal caps. The TUNEL analysis of embryos and caps showed that ƒnDNp63 produced a decrease of apoptosis. To investigate if Slug or msx1 could modify the expression of DNp63 we carried out gain of function experiments of these two genes. Our results showed that Slug produce an expansion in the DNp63 domain while msx1 has not effect on it. Finally, we analyzed whether DNp63 was able to regulate the transcription of some apoptotic and antiapoptotic factors like caspases and Bcl family members. Our results suggest that DNp63 is acting as an antiapoptotic factor downstream Slug in the control of neural crest apoptosis.