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Curr Biol 1997 Oct 01;710:747-57. doi: 10.1016/s0960-9822(06)00333-2.
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p53 activity is essential for normal development in Xenopus.

Wallingford JB , Seufert DW , Virta VC , Vize PD .

BACKGROUND: The tumor suppressor p53 plays a key role in regulating the cell cycle and apoptosis in differentiated cells. Mutant mice lacking functional p53 develop normally but die from multiple neoplasms shortly after birth. There have been hints that p53 is involved in morphogenesis, but given the relatively normal development of p53 null mice, the significance of these data has been difficult to evaluate. To examine the role of p53 in vertebrate development, we have determined the results of blocking its activity in embryos of the frog Xenopus laevis. RESULTS: Two different methods have been used to block p53 protein activity in developing Xenopus embryos--ectopic expression of dominant-negative forms of human p53 and ectopic expression of the p53 negative regulator, Xenopus dm-2. In both instances, inhibition of p53 activity blocked the ability of Xenopus early blastomeres to undergo differentiation and resulted in the formation of large cellular masses reminiscent of tumors. The ability of mutant p53 to induce such developmental tumors was suppressed by co-injection with wild-type human or wild-type Xenopus p53. Cells expressing mutant p53 activated zygotic gene expression and underwent the mid-blastula transition normally. Such cells continued to divide at approximately normal rates but did not form normal embryonic tissues and never underwent terminal differentiation, remaining as large, yolk-filled cell masses that were often associated with the neural tube or epidermis. CONCLUSIONS: In Xenopus, the maternal stockpile of p53 mRNA and protein seems to be essential for normal development. Inhibiting p53 function results in an early block to differentiation. Although it is possible that mutant human p53 proteins have a dominant gain-of-function or neomorphic activity in Xenopus, and that this is responsible for the development of tumors, most of the evidence indicates that this is not the case. Whatever the basis of the block to differentiation, these results indicate that Xenopus embryos are a sensitive system in which to explore the role of p53 in normal development and in developmental tumors.

PubMed ID: 9368757
Article link: Curr Biol

Species referenced: Xenopus laevis
Genes referenced: gsc lsamp tbxt tp53
GO keywords: cell differentiation
Antibodies: Lsamp Ab1 Somite Ab2

Disease Ontology terms: cancer
Phenotypes: Xla Wt + tp53 (Fig.1.B, C) [+]

Article Images: [+] show captions