Apoptosis caused by p53-induced protein with death domain (PIDD) depends on the death adapter protein RAIDD

Abstract

The p53 tumor suppressor promotes cell cycle arrest or apoptosis in response to diverse stress stimuli. p53-mediated cell death depends in large part on transcriptional up-regulation of target genes. One of these targets, P53-induced protein with a death domain (PIDD), was shown to function as a mediator of p53-dependent apoptosis. Here we show that PIDD is a cytoplasmic protein, and that PIDD-induced apoptosis and growth suppression in embryonic fibroblasts depend on the adaptor protein receptorinteracting protein (RIP)-associated ICH-1͞CED-3 homologous protein with a death domain (RAIDD). We provide evidence that PIDD-induced cell death is associated with the early activation of caspase-2 and later activation of caspase-3 and -7. Our results also show that caspase-2 ؊/؊ , in contrast to RAIDD ؊/؊ , mouse embryonic fibroblasts, are only partially resistant to PIDD. Our findings suggest that caspase-2 contributes to PIDD-mediated cell death, but that it is not the sole effector of this pathway.caspase-2 T he tumor suppressor p53 is a sequence-specific transcription factor that promotes cell cycle arrest or apoptosis in response to cellular stress (1). Transcriptional activation of the p21 WAF1 cyclin-dependent kinase inhibitor plays a key role in the induction of cell cycle arrest by p53 (2). p53-dependent apoptosis is regulated, at least in part, by transcriptional activation of its target genes (3), and this process highly depends on cytochrome c release and the Apaf-1͞caspase-9 activation pathway (4, 5). Although a number of candidate p53-effector molecules have been reported, it is yet unclear whether each contributes a part of the full response, or whether specific subsets of these genes are required for death in different cell types or in response to different signals (3).Among the identified apoptotic effectors of p53, P53-induced protein with a death domain (PIDD)͞leucine-rich DD (LRDD) is a 915-aa protein in mice (910 aa in humans) containing seven tandem LR repeats in the N terminus and a DD in the C terminus (6, 7). The dual domain structure of PIDD suggests that it may function as a key adapter protein that links additional components of the p53 apoptosis pathway. Using the method of differential display, PIDD was identified as a p53-up-regulated gene in a p53-null Friend-virus-transformed mouse erythroleukemia cell line (DP16.1͞p53ts) that stably expresses a temperature-sensitive (ts) Trp-53 mutant allele. DP16.1͞p53ts cells undergo apoptosis after expression of the wild-type p53 conformation at 32°C. PIDD mRNA is induced by ␥-irradiation in a p53-dependent manner, and the basal level of PIDD mRNA depends on p53 gene status. Overexpression of PIDD also inhibits cell growth in a p53-like manner by inducing apoptosis. Antisense inhibition of PIDD expression was shown to attenuate apoptosis in response to p53 activation and DNA damage, suggesting that PIDD expression is required for p53-dependent death (7).Recently, PIDD was found to be present in a large protein complex containing caspase-2 and the ad...

The expression of p53-induced protein with death domain (Pidd) and apoptosis in oral squamous cell carcinoma

“…In vitro studies demonstrated that exogenous expression of Pidd results in apoptosis and that Pidd interacts with two other apoptotic signalling proteins, FADD (Fas-associated death domain protein) and RAIDD (receptorinteracting protein-associated ICH-1/CED-3 homologous protein with a death domain). The results of these studies suggest that Pidd mediates apoptosis through activation of the FADD -caspase 8 and the RAIDD -caspase 2 complexes, and thus contributes to both the mitochondrial and death receptor signalling pathways (Tinel and Tschopp, 2004;Berube et al, 2005). The data shown here suggest that Pidd may be one of the factors that mediate apoptosis in OSCC, but further studies are needed to clarify the apoptotic signalling pathways that are activated in this context.…”

“…Pidd has been characterised in mouse and human cell lines as a critical component of apoptotic signalling in response to DNA damage Berube et al, 2005). In vitro studies demonstrated that exogenous expression of Pidd results in apoptosis and that Pidd interacts with two other apoptotic signalling proteins, FADD (Fas-associated death domain protein) and RAIDD (receptorinteracting protein-associated ICH-1/CED-3 homologous protein with a death domain).…”

“…This provided a sensitive and specific measurement of Pidd expression, but did not allow Pidd expression to be studied at the single-cell level. We performed immunohistochemical staining of selected cases of OSCC using an antiserum against Pidd (Berube et al, 2005) but were not able to demonstrate specific staining for Pidd. In situ hybridisation of tumour sections for Pidd mRNA was also unsuccessful, probably due to the low level of expression within individual cells.…”

“…The structural features of the Pidd protein suggest that it may function as an adaptor protein that links other apoptotic signalling molecules. Indeed, the Pidd protein has been shown to form a complex with signalling molecules in both the death receptor and mitochondrial pathways (Telliez et al, 2000;Tinel and Tschopp, 2004;Berube et al, 2005). Currently, little is known about the pathophysiologic role of Pidd in clinical cancers, and whether Pidd expression may be used as a marker of apoptotic function that can guide cancer therapy.…”

Regulation of PIDD auto-proteolysis and activity by the molecular chaperone Hsp90

“…1 The activation platform for caspase-2 has long remained enigmatic until the PIDDosome was identified, a complex consisting of PIDD (p53-induced protein with a death domain; LRDD), the adaptor protein RAIDD (RIP-associated protein with a death domain; CRADD) and caspase-2. [2][3][4] PIDD can also recruit RIP1 and NEMO in response to DNA damage, leading to NF-kB activation 5,6 and was also recently described in a nuclear complex with DNA-PKcs and caspase-2, formed in response to g-irradiation having a role in DNA repair and cell cycle checkpoint maintenance. 7 The opposing signalling functions of PIDD, namely its prosurvival (NF-kB activation) and pro-death (caspase-2 activation) functions, were shown to be dependent on different active fragments of PIDD, generated by auto-processing.…”