Poly(ADP-ribose) polymerase 3 (PARP3), a newcomer in cellular response to DNA damage and mitotic progression.
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ABSTRACT:
SUBMITTER: Boehler C
PROVIDER: S-EPMC3041075 | biostudies-other | 2011 Feb
REPOSITORIES: biostudies-other
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Project description:Poly(ADP-ribose) polymerase-1 (PARP-1) was recently identified as a platinum-DNA damage response protein. To investigate the properties of binding of PARP-1 to different platinum-DNA adducts in greater detail, biotinylated DNA probes containing a site-specific cisplatin 1,2-d(GpG) or 1,3-d(GpTpG) intrastrand cross-link or a cisplatin 5'-GC/5'-GC interstrand cross-link (ICL) were utilized in binding assays with cell-free extracts (CFEs) in vitro. The activated state of PARP-1 was generated by treatment of cells with a DNA-damaging agent or by addition of NAD(+) to CFEs. PARP-1 binds with a higher affinity to cisplatin-damaged DNA than to undamaged DNA, and the amount of protein that binds to the most common cisplatin-DNA cross-link, 1,2-d(GpG), is greater than the amount that binds to other types of cisplatin-DNA cross-links. Both DNA damage-activated PARP-1 and unactivated PARP-1 bind to cisplatin-damaged DNA, and both automodified PARP-1 and cleaved PARP-1 bind to cisplatin-DNA lesions. The role of poly(ADP-ribose) (pADPr) in mediating binding of PARP-1 to platinum damage was further investigated. The extent of binding of PARP-1 to the cisplatin 1,2-d(GpG) cross-link decreases upon automodification, and overactivated PARP-1 loses its affinity for the cross-link. Elimination of pADPr facilitates binding of PARP-1 to the cisplatin 1,2-d(GpG) cross-link. PARP-1 also binds to DNA damaged by other platinum compounds, including oxaliplatin and pyriplatin, indicating protein affinity for the damage in an adduct-specific manner rather than recognition of distorted DNA. Our results reveal the unique binding properties for binding of PARP-1 to platinum-DNA damage, providing insights into, and a better understanding of, the cellular response to platinum-based anticancer drugs.
| S-EPMC2912421 | biostudies-literature
Project description:Parthanatos is programmed cell death mediated by poly(ADP-ribose) polymerase 1 (PARP1) after DNA damage. PARP1 acts by catalyzing the transfer of poly(ADP-ribose) (PAR) polymers to various nuclear proteins. PAR is subsequently cleaved, generating protein-free PAR polymers, which are translocated to the cytoplasm where they associate with cytoplasmic and mitochondrial proteins, altering their functions and leading to cell death. Proteomic studies revealed that several proteins involved in endocytosis bind PAR after PARP1 activation, suggesting endocytosis may be affected by the parthanatos process. Endocytosis is a mechanism for cellular uptake of membrane-impermeant nutrients. Rab5, a small G-protein, is associated with the plasma membrane and early endosomes. Once activated by binding GTP, Rab5 recruits its effectors to early endosomes and regulates their fusion. Here, we report that after DNA damage, PARP1-generated PAR binds to Rab5, suppressing its activity. As a result, Rab5 is dissociated from endosomal vesicles, inhibiting the uptake of membrane-impermeant nutrients. This PARP1-dependent inhibition of nutrient uptake leads to cell starvation and death. It thus appears that this mechanism may represent a novel parthanatos pathway.
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Project description:Biomineralization of the extracellular matrix is an essential, regulated process. Inappropriate mineralization of bone and the vasculature has devastating effects on patient health, yet an integrated understanding of the chemical and cell biological processes that lead to mineral nucleation remains elusive. Here, we report that biomineralization of bone and the vasculature is associated with extracellular poly(ADP-ribose) synthesized by poly(ADP-ribose) polymerases in response to oxidative and/or DNA damage. We use ultrastructural methods to show poly(ADP-ribose) can form both calcified spherical particles, reminiscent of those found in vascular calcification, and biomimetically calcified collagen fibrils similar to bone. Importantly, inhibition of poly(ADP-ribose) biosynthesis in vitro and in vivo inhibits biomineralization, suggesting a therapeutic route for the treatment of vascular calcifications. We conclude that poly(ADP-ribose) plays a central chemical role in both pathological and physiological extracellular matrix calcification.
| S-EPMC6581741 | biostudies-literature
Project description:Purpose of reviewPoly(ADP-ribose) polymerase (PARP) inhibitors have transformed treatment paradigms in multiple cancer types defined by homologous recombination deficiency (HRD) and have become the archetypal example of synthetic lethal targeting within the DNA damage response (DDR). Despite this success, primary and acquired resistance to PARP inhibition inevitability threaten the efficacy and durability of response to these drugs. Beyond PARP inhibitors, recent advances in large-scale functional genomic screens have led to the identification of a steadily growing list of genetic dependencies across the DDR landscape. This has led to a wide array of novel synthetic lethal targets and corresponding inhibitors, which hold promise to widen the application of DDR inhibitors beyond HRD and potentially address PARP inhibitor resistance.Recent findingsIn this review, we describe key synthetic lethal interactions that have been identified across the DDR landscape, summarize the early phase clinical development of the most promising DDR inhibitors, and highlight relevant combinations of DDR inhibitors with chemotherapy and other novel cancer therapies, which are anticipated to make an impact in rationally selected patient populations.SummaryThe DDR landscape holds multiple opportunities for synthetic lethal targeting with multiple novel DDR inhibitors being evaluated on early phase clinical trials. Key challenges remain in optimizing the therapeutic window of ATR and WEE1 inhibitors as monotherapy and in combination approaches.
| S-EPMC9371461 | biostudies-literature
Project description:Breast cancer susceptibility gene 2 (BRCA2) plays a key role in DNA damage repair for maintaining genomic stability. Previous studies have shown that BRCA2 contains three tandem oligonucleotide/oligosaccharide binding folds (OB-folds) that are involved in DNA binding during DNA double-strand break repair. However, the molecular mechanism of BRCA2 in DNA damage repair remains elusive. Unexpectedly, we found that the OB-folds of BRCA2 recognize poly(ADP-ribose) (PAR) and mediate the fast recruitment of BRCA2 to DNA lesions, which is suppressed by PARP inhibitor treatment. Cancer-associated mutations in the OB-folds of BRCA2 disrupt the interaction with PAR and abolish the fast relocation of BRCA2 to DNA lesions. The quickly recruited BRCA2 is important for the early recruitment of exonuclease 1(EXO1) and is involved in DNA end resection, the first step of homologous recombination (HR). Thus, these findings uncover a molecular mechanism by which BRCA2 participates in DNA damage repair.
| S-EPMC4794993 | biostudies-literature
Project description:The retinoblastoma (Rb) tumor suppressor is a key regulator of cell cycle checkpoints but also protects against cell death induced by stresses such as DNA damage and death receptor ligation. We report here that cell death of Rb-deficient cells exposed to key genotoxic agents was associated with increased expression of S phase-specific E2F target genes and cell death consistently occurred in the S phase of the cell cycle. Cell cycle arrest induced by serum starvation prevented S phase entry, attenuated DNA damage, and promoted survival, suggesting that Rb-null cells die due to a failure to prevent S phase entry. DNA damage-induced death of Rb-null cells was associated with nucleotide depletion, higher activity of poly-ADP-ribose-polymerase (Parp), and cell death that was primarily necrotic. Knockdown of Parp-1 or chemical inhibition of Parp activity prevented nucleotide depletion and restored the viability of Rb-deficient cells to wild-type levels. Furthermore, chemical inhibition of Parp activity in vivo attenuated the cytotoxic effects of cisplatin against Rb-deficient tumors, arguing that Parp inhibitors should not be used therapeutically in combination with genotoxic drugs against tumors that are inactivated for the Rb tumor suppressor.
| S-EPMC2994938 | biostudies-literature
Project description:Poly (ADP-ribose) polymerases (PARPs) catalyze the transfer of multiple poly(ADP-ribose) units onto target proteins. Poly(ADP-ribosyl)ation plays a crucial role in a variety of cellular processes including, most prominently, auto-activation of PARP at sites of DNA breaks to activate DNA repair processes. In humans, PARP1 (the founding and most characterized member of the PARP family) accounts for more than 90% of overall cellular PARP activity in response to DNA damage. We have found that, in contrast with animals, in Arabidopsis thaliana PARP2 (At4g02390), rather than PARP1 (At2g31320), makes the greatest contribution to PARP activity and organismal viability in response to genotoxic stresses caused by bleomycin, mitomycin C or gamma-radiation. Plant PARP2 proteins carry SAP DNA binding motifs rather than the zinc finger domains common in plant and animal PARP1 proteins. PARP2 also makes stronger contributions than PARP1 to plant immune responses including restriction of pathogenic Pseudomonas syringae pv. tomato growth and reduction of infection-associated DNA double-strand break abundance. For poly(ADP-ribose) glycohydrolase (PARG) enzymes, we find that Arabidopsis PARG1 and not PARG2 is the major contributor to poly(ADP-ribose) removal from acceptor proteins. The activity or abundance of PARP2 is influenced by PARP1 and PARG1. PARP2 and PARP1 physically interact with each other, and with PARG1 and PARG2, suggesting relatively direct regulatory interactions among these mediators of the balance of poly(ADP-ribosyl)ation. As with plant PARP2, plant PARG proteins are also structurally distinct from their animal counterparts. Hence core aspects of plant poly(ADP-ribosyl)ation are mediated by substantially different enzymes than in animals, suggesting the likelihood of substantial differences in regulation.
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Project description:Androgen deprivation is the standard treatment for advanced prostate cancer (PCa), but most patients ultimately develop resistance and tumor recurrence. We found that MYB is transcriptionally activated by androgen deprivation therapy or genetic silencing of the androgen receptor (AR). MYB silencing inhibited PCa growth in culture and xenografts in mice. Microarray data revealed that c-Myb and AR shared a subset of target genes that encode DNA damage response (DDR) proteins, suggesting that c-Myb may supplant AR as the dominant regulator of their common DDR target genes in AR inhibition-resistant or AR-negative PCa. Gene signatures including AR, MYB, and their common DDR-associated target genes positively correlated with metastasis, castration resistance, tumor recurrence, and decreased survival in PCa patients. In culture and in xenograft-bearing mice, a combination strategy involving the knockdown of MYB, BRCA1, or TOPBP1 or the abrogation of cell cycle checkpoint arrest with AZD7762, an inhibitor of the checkpoint kinase Chk1, increased the cytotoxicity of the poly[adenosine 5'-diphosphate (ADP)-ribose] polymerase (PARP) inhibitor olaparib in PCa cells. Our results reveal new mechanism-based therapeutic approaches for PCa by targeting PARP and the DDR pathway involving c-Myb, TopBP1, ataxia telangiectasia mutated- and Rad3-related (ATR), and Chk1.
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Project description:Following DNA double-strand breaks, poly(ADP-ribose) (PAR) is quickly and heavily synthesized to mediate fast and early recruitment of a number of DNA damage response factors to the sites of DNA lesions and facilitates DNA damage repair. Here, we found that EXO1, an exonuclease for DNA damage repair, is quickly recruited to the sites of DNA damage via PAR-binding. With further dissection of the functional domains of EXO1, we report that the PIN domain of EXO1 recognizes PAR both in vitro and in vivo and the interaction between the PIN domain and PAR is sufficient for the recruitment. We also found that the R93G variant of EXO1, generated by a single nucleotide polymorphism, abolishes the interaction and the early recruitment. Moreover, our study suggests that the PAR-mediated fast recruitment of EXO1 facilities early DNA end resection, the first step of homologous recombination repair. We observed that other PIN domains could also recognize DNA damage-induced PAR. Taken together, our study demonstrates a novel class of PAR-binding module that plays an important role in DNA damage response.
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Project description:Ribosomal proteins are the building blocks of ribosome biogenesis. Beyond their known participation in ribosome assembly, the ribosome-independent functions of ribosomal proteins are largely unknown. Here, using immunoprecipitation, subcellular fractionation, His-ubiquitin pulldown, and immunofluorescence microscopy assays, along with siRNA-based knockdown approaches, we demonstrate that ribosomal protein L6 (RPL6) directly interacts with histone H2A and is involved in the DNA damage response (DDR). We found that in response to DNA damage, RPL6 is recruited to DNA damage sites in a poly(ADP-ribose) polymerase (PARP)-dependent manner, promoting its interaction with H2A. We also observed that RPL6 depletion attenuates the interaction between mediator of DNA damage checkpoint 1 (MDC1) and H2A histone family member X, phosphorylated (?H2AX), impairs the accumulation of MDC1 at DNA damage sites, and reduces both the recruitment of ring finger protein 168 (RNF168) and H2A Lys-15 ubiquitination (H2AK15ub). These RPL6 depletion-induced events subsequently inhibited the recruitment of the following downstream repair proteins: tumor protein P53-binding protein 1 (TP53BP1) and BRCA1, DNA repair-associated (BRCA1). Moreover, the RPL6 knockdown resulted in defects in the DNA damage-induced G2-M checkpoint, DNA damage repair, and cell survival. In conclusion, our study identifies RPL6 as a critical regulatory factor involved in the DDR. These findings expand our knowledge of the extraribosomal functions of ribosomal proteins in cell physiology and deepen our understanding of the molecular mechanisms underlying DDR regulation.
| S-EPMC6393625 | biostudies-literature