title: The promyelocytic leukaemia protein tumour suppressor functions as a transcriptional regulator of p63.
abstract: p63 plays unique developmental roles in epidermal morphogenesis, despite its structural similarity with p53. The p63 gene has two distinct promoters, coding for proteins containing an N-terminal transactivation domain (TA isoforms) and for proteins lacking this region (DeltaN isoforms). The full-length transcriptionally active TAp63 isoforms are capable of transactivating the majority of the p53 target promoters thus inducing cell cycle arrest and apoptosis. On the contrary, the DeltaNp63 isoforms seem to counteract the transactivation activities of p53 and TAp63 proteins, thus possibly conferring a proliferative advantage to cancer cells. However, the molecular mechanisms controlling the transcriptional activity of p63 remain largely unclear. Here we present data indicating that (i) the promyelocytic leukaemia protein (PML) physically interacts with p63, (ii) p63 is localized into the PML nuclear-bodies (PML-NBs) in vivo, and (iii) PML regulates p63 transcriptional activity. We show that the interaction of p63 with PML increases the levels of p63 in cultured cells as well as its ability to transactivate the p53-responsive elements of the GADD45, p21 and bax promoters. These data are consistent with a general role for PML as a functional modulator of all the p53 family members. Our findings strengthen the relevance of the cross talk between PML and the p53 family members, imply a new tumour suppressive function of PML and unveil a possible role for PML in epidermal morphogenesis and differentiation.
authors: Department of Pathology, Cancer Biology and Genetics Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
authors: Francesca
authors: F
authors: Bernassola
authors: Andrew
authors: A
authors: Oberst
authors: Gerry
authors: G
authors: Melino
authors: Pier Paolo
authors: PP
authors: Pandolfi
mesh_terms: D004268:DNA-Binding Proteins; D016147:Genes, Tumor Suppressor / Q000502:physiology*; D006801:Humans; D009363:Neoplasm Proteins / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology*; D010750:Phosphoproteins / Q000502:physiology*; D000071156:Promyelocytic Leukemia Protein; D015534:Trans-Activators / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D000071156:Promyelocytic Leukemia Protein; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human