Poly(ADP-ribosyl)ation is required for p53-dependent signal transduction induced by radiation

Abstract

p53 and poly(ADP-ribose) polymerase (PARP) are both DNA damage recognition proteins and can be functionally activated by DNA strand breaks. To understand the functional interaction between these two proteins, the eects of a PARP inhibitor, 3-aminobenzamide (3AB), on the p53 pathway were investigated in human glioblastoma cells with dierent p53 status. Consistent with previous studies, irradiation with g-rays induced both p53 and WAF1 accumulation in A-172 cells (wtp53) but not in T98G cells (mp53). However, the presence of 3AB but not its analog suppressed radiation-induced accumulation of wtp53 and the expression of WAF1 and MDM2. Similar results were also obtained from U87MG, another human glioblastoma cell line with wtp53 status. Northern blotting analysis showed that 3AB inhibited the g-ray-induced WAF1 gene expression. Moreover, 3AB but not its analog inhibited irradiationinduced activation of sequence-speci®c DNA binding of wtp53 as detected using 32 P-labeled or biotin-labeled p53 consensus sequence (p53CON). However, immunoblotting with an anti-poly(ADP-ribose) antibody showed that p53 proteins of the p53CON-bound fraction did not contain poly(ADP-ribose) (PAR). These ®ndings suggested that poly(ADP-ribosyl)ation is required for rapid accumulation of p53, activation of p53 sequence-speci®c DNA binding and its transcriptional activity after DNA damage.

Poly(ADP-ribose) Polymerase-1 Is a Positive Regulator of the p53-mediated G1 Arrest Response following Ionizing Radiation

“…The effects of IQ treatment on the p53 response to IR observed in this study are consistent with previous inhibitor studies (12,20,21,46); however, the use of NAD analogs to inhibit PARP activity can be criticized because of the possibility of nonspecific effects on other NAD-dependent processes, for example, those that require mono(ADP-ribosyl) transferases (47). In this study, trans-dominant inhibition of PARP-1 by PARP-1 DBD overexpression led to disruption of p21 induction and suppression of p53-mediated G 1 arrest in MCF-7 cells.…”

“…A number of studies have investigated the role of PARP-1 in the p53 response to DNA damage. Several studies indicate that disruption of PARP function by chemical inhibition leads to suppression of p53-dependent transactivation in response to IR (12,20,21). Chemical inhibition of PARP leads to loss of the G 1 checkpoint and accumulation of cells in G 2 /M following N-methyl-N-nitro-N-nitrosoguanidine treatment (22) or IR (20).…”

Activation and activities of the p53 tumour suppressor protein

“…The extreme C terminus of the protein controls its sequence-specific DNA binding and transcriptional activity, and these functions can be influenced by a multitude of covalent and non-covalent modifications within the C terminus. Modifications suggested to be involved in activation of p53 include sumoylation (Gostissa et al, 1999;Rodriguez et al, 1999;Muller et al, 2000), phosphorylation, dephosphorylation, acetylation, glycosylation (Shaw et al, 1996), ribosylation (Vaziri et al, 1997;Wang et al, 1998;Simbulan-Rosenthal et al, 1999) and redox regulation.…”

Enhancement of radiosensitivity by combined ceramide and dimethylsphingosine treatment in lung cancer cells

“…The diversity of the ceramideinducing extracellular stimuli indicates the function of ceramide as a common mediator of various apoptotic mechanisms (Wang et al, 1998;. In addition, the treatment with exogenous short chain homologues of ceramide mimics endogenously generated ceramide and induces apoptosis.…”