PARP is important for genomic stability but dispensable in apoptosis

Abstract

Mice lacking the gene encoding poly(ADP-ribosyl) transferase (PARP or ADPRT) display no phenotypic abnormalities, although aged mice are susceptible to epidermal hyperplasia and obesity in a mixed genetic background. Whereas embryonic fibroblasts lacking PARP exhibit normal DNA excision repair, they grow more slowly in vitro. Here we investigated the putative roles of PARP in cell proliferation, cell death, radiosensitivity, and DNA recombination, as well as chromosomal stability. We show that the proliferation deficiency in vitro and in vivo is most likely caused by a hypersensitive response to environmental stress. Although PARP is specifically cleaved during apoptosis, cells lacking this molecule apoptosed normally in response to treatment with anti-Fas, tumor neurosis factor ␣, ␥-irradiation, and dexamethasone, indicating that PARP is dispensable in apoptosis and that PARP−/− thymocytes are not hypersensitive to ionizing radiation. Furthermore, the capacity of mutant cells to carry out immunoglobulin class switching and V(D)J recombination is normal. Finally, primary PARP mutant fibroblasts and splenocytes exhibited an elevated frequency of spontaneous sister chromatid exchanges and elevated micronuclei formation after treatment with genotoxic agents, establishing an important role for PARP in the maintenance of genomic integrity.

Overexpression of dominant negative PARP interferes with tumor formation of HeLa cells in nude mice: Evidence for increased tumor cell apoptosis in vivo

“…It is well known that PARP and other DNA repairassociated enzymes like DNA-dependent protein kinase are cleaved by caspase-3 during apoptosis (Nicholson et al, 1995;Tewari et al, 1995;Teraoka et al, 1996;Song et al, 1996). It is possible that this PARP cleavage, rather than the presence of PARP itself, is important for some apoptotic programs, since thymocytes from PARP 7/7 mice exhibit normal apoptotic responses after a variety of stimuli (Wang et al, 1997), in contrast to PARP 7/7 cells that were transfected with an uncleavable PARP mutant (Oliver et al, 1998). These results are in con¯ict with the ®nding that depletion of PARP by antisense RNA and absence of the early burst of poly(ADP-ribosyl)ation that normally occurs prior to PARP cleavage interferes with anti-Fas and cycloheximide-induced apoptosis (Simbulan et al, 1998).…”

Identification of Poly (ADP-ribose) Polymerase-1 (PARP-1) as a Novel Krüppel-like Factor 8-interacting and -regulating Protein

“…Using the internal ZF deletion mutants and point mutants of KLF8 (19) (Fig. 2, B and C) for the co-IP experiments, we determined that deletion of ZF1 resulted in partial loss of the interaction and that deletion of ZF2 almost abolished the interaction (Fig.…”

“…T80, the immortalized human ovarian epithelial cell line, was kindly provided by Dr. Jinsong Liu (20). PARP-1 Ϫ/Ϫ and PARP-1 ϩ/ϩ mouse embryonic fibroblast (MEF) cells were kind gifts from Dr. Zhao-qi Wang (19). Primary MEFs were isolated as described previously (21,22) and kindly provided by Dr. Hamid Boulares of Louisiana State University.…”

“…ZF1,2mCs is the double mutant of ZF1mCs and ZF2mCs. Human PARP-1 expression vector was kindly provided by Dr. Zhao-qi Wang (Leibniz Institute For Age Research-Fritz Lipmann Institute, Jena, Germany) (19). Myc-PARP-1 was generated by cloning PARP-1 into the pHAN vector using the primers forward and reverse: 5Ј-agt aga tct gcg gag tct tc-3Ј and 5Ј-act ccc ggg tta cca cag g-3Ј.…”

Human Gyrovirus-Apoptin Interferes with the Cell Cycle and Induces G2/M Arrest Prior to Apoptosis

“…While apoptosis is highly regulated in normal tissue, most of the cancerous tissues show a deregulated apoptotic process due to the mutation of genes indispensable for apoptosis (Pettigrew and Cotter 2009), or genomic stability (Wang et al 1997;Wiechec 2011). This enables the replication and proliferation of defective cells.…”