First published online December 15, 2003
Journal of Cell Science 117, 204e (2004)
© The Company of Biologists Limited
Tumour suppressor siblings cooperate
The tumour suppressor p53 exerts its effects by regulating transcription of various genes required for cell cycle control, apoptosis and DNA repair. Its close relative p73 is also a transcription factor, but some splice forms lack a transactivation domain (e.g.
Np73
) and thus might play an antagonistic role. The extent to which the regulatory circuits involving p53 and p73 - particularly
Np73
- overlap is unclear. Sétha Douc-Rasy and co-workers have therefore examined their interplay in malignant neuroblastoma cells, in which p53 is sequestered outside the nucleus (see p. 293). Surprisingly, they observe that both full-length p53 (TAp73
) and
Np73
stabilize p53 protein. However, TAp73 causes p53 to return to the nucleus;
Np73
does not. The authors also observe that TAp73 and
Np73
have differential effects on genes downstream of p53 - TAp73 induces expression of the apoptosis protein PUMA, for example, but
Np73
does not. In each of these cases, the effect requires wild-type p53. By contrast, TAp73 can stimulate synthesis of the cell cycle inhibitor p21 even when endogenous p53 is mutated. These results indicate that p73 can have p53-independent effects but that, frequently, the regulatory pathways involving the proteins overlap, and the truncated
Np73
plays a repressive role.
Related articles in JCS:
- Differential response of p53 target genes to p73 overexpression in SH-SY5Y neuroblastoma cell line
- David Goldschneider, Etienne Blanc, Gilda Raguénez, Michel Barrois, Agnès Legrand, Gwenaëlle Le Roux, Hedi Haddada, Jean Bénard, and Sétha Douc-Rasy
JCS 2004 117: 293-301.
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