The function of PML in p53-dependent apoptosis

The PML gene of acute promyelocytic leukaemia (APL) encodes a growth- and t umour-suppresor protein that is essential for several apoptotic signals. Th e mechanisms by which PML exerts its pro-apoptotic function are still unkno wn. Here we show that PML acts as a transcriptional cc-activator with p53. PML physically interacts with p53 both in vitro and in vivo and co-localize s with p53 in the PML nuclear body (PML-NB), The co-activatory role of PML depends on its ability to localize in the PML-NB, p53-dependent, DNA-damage -induced apoptosis, transcriptional activation by p53, the DNA-binding abil ity of p53, and the induction of p53 target genes such as Bar and p21 upon gamma-irradiation are all impaired in PML-/- primary cells. These results d efine a new PML-dependent, p53-regulatory pathway for apoptosis and shed ne w light on the function of PML in tumour suppression.