Pidd, a new death-domain-containing protein, is induced by p53 and promotes apoptosis

The p53 tumour suppressor promotes cell-cycle arrest or apoptosis in respon se to cellular stress, such as DNA damage and oncogenesis. This role of p53 is important for its tumour-suppression function(1) and depends, at least in part, on its ability to bind to specific DNA sequences and activate the transcription of target genes(2-4). The pathway through which p53 promotes apoptosis is not fully understood. Here we describe a new gene regulated by p53 that encodes a predicted protein of 915 amino acids in mice (910 amino acids in humans), which we have named Pidd. The mouse Pidd cDNA contains a p53 consensus DNA binding sequence upstream of the Pidd-coding region. Thi s sequence element bound to p53 and conferred p53-dependent inducibility on a heterologous reporter gene. Moreover, Pidd RNA was induced by ionizing r adiation in a p53-dependent manner and the basal level of Pidd RNA was depe ndent on Trp53 status. Overexpression of Pidd inhibited cell growth in a p5 3-like manner by inducing apoptosis. Antisense inhibition of Pidd expressio n attenuated p53-mediated apoptosis. Our data suggest that Pidd is an effec tor of p53-dependent apoptosis.