In several cell types tumour suppressor p53 induces apoptosis largely via Puma but Noxa can contribute.
The ability of p53 to induce apoptosis in cells with damaged DNA is thought to contribute greatly to its tumour suppressor function. P53 has been proposed to induce apoptosis via numerous transcriptional targets or even by direct cytoplasmic action. Two transcriptional targets shown to mediate its apoptotic role in several cell types encode Noxa and Puma, BH3-only members of the Bcl-2 family. To test if their functions in p53-dependent apoptosis overlap, we generated mice lacking both. These mice develop normally and no tumours have yet arisen. In embryonic fibroblasts, the absence of both Noxa and Puma prevented induction of apoptosis by etoposide. Moreover, following whole body gamma-irradiation, the loss of both proteins protected thymocytes better than loss of Puma alone. Indeed, their combined deficiency protected thymocytes as strongly as loss of p53 itself. These results indicate that, at least in fibroblasts and thymocytes, p53-induced apoptosis proceeds principally via Noxa and Puma, with Puma having the predominant role in diverse cell types. The absence of tumours in the mice suggests that tumour suppression by p53 requires functions in addition to induction of apoptosis.
Michalak
E M
EM
Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.
Villunger
A
A
Adams
J M
JM
Strasser
A
A
D017500:Adenovirus E1A Proteins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D002472:Cell Transformation, Viral; D005047:Etoposide / Q000633:toxicity; D005347:Fibroblasts / Q000187:drug effects / Q000821:virology; D005720:Gamma Rays; D008214:Lymphocytes / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009374:Neoplasms, Experimental / Q000209:etiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000528:radiation effects; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000502:physiology*
D017500:Adenovirus E1A Proteins; D051017:Apoptosis Regulatory Proteins; C488588:PUMA protein, mouse; C408009:Pmaip1 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D005047:Etoposide