XSlug and BMP4/msx-1 genes regulate the apoptosis in the neural crest of Xenopus laevis

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

Valle Nevado, Chile

Congreso; First International Meeting of the Latinamerican Society of Developmental Biology; 2003

Latinamerican Society of Developmental Biology

Apoptosis is a physiological process of cell elimination that function as an essential mechanism in maintaining normal tissue homeostasis. This programmed cell death refers to the naturally occurring cell death that is part of the developmental program of an organism. This loss of cells can be fundamental to some developmental processes and serves many functions, such as sculpting or deleting structures, controlling cell number, and eliminating abnormal, misplaced, or nonfunctional cells. Studies in the chick have shown that regions from where neural crest cells migrate are separated by stripes where all presumptive neural crest cells undergo apoptosis. It has been demonstrated that BMP4, through activation of msx family genes, induce apoptosis of these neural crest cells. On the other hand, there are evidences in C. elegans which suggest that a Slug family gene, called ces-1, blocks the programmed cell death in specific cells. Our results show that apoptosis is localized in the neural crest region and that during neural crest development BMP4 and Xmsx-1 promote apoptosis while XSlug acts as an antiapoptotic gene. In the present work, we carried out rescue experiments in animal caps. We found that Xmsx-1 is able to rescue apoptosis in animal caps when was coinjected with XSlug or with the dominant negative of Xmsx-1. In order to explore the identity of the BMP molecule involved in the induction of apoptosis, we injected animal caps with BMP1, BMP4 and BMP7 dominant negatives. Our results indicate that BMP4 is the only one molecule involved in promoting the apoptotic process. To investigate if apoptosis is a feature of the neural crest and if it could be affected by other signals of the embryo, we made graft experiments in which explants of neural crest tissue were relocated to more ventral and posterior positions. We found that apoptosis is a characteristic of the neural crest and is not modified by the environment. Finally, in this work we analyze if the Bcl-2/Bax pathway is involved in the regulation of apoptosis in response to XSlug or BMP4/Xmsx genes.