Rescue of neural tube defects in Pax-3-deficient embryos by p53 loss of function: implications for Pax-3- dependent development and tumorigenesis.

Pax-3 is a transcription factor that is expressed in the neural tube, neural crest, and dermomyotome. We previously showed that apoptosis is associated with neural tube defects (NTDs) in Pax-3-deficient Splotch (Sp/Sp) embryos. Here we show that p53 deficiency, caused by germ-line mutation or by pifithrin-alpha, an inhibitor of p53-dependent apoptosis, rescues not only apoptosis, but also NTDs, in Sp/Sp embryos. Pax-3 deficiency had no effect on p53 mRNA, but increased p53 protein levels. These results suggest that Pax-3 regulates neural tube closure by inhibiting p53-dependent apoptosis, rather than by inducing neural tube-specific gene expression.