Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.30 (PARP)
 13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proteolytic cleavage of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) to fragments of 89 kD and 24 kD is widely observed during apoptotic cell death. In the present study, labelling of a Mr approximately 89000 polypeptide was demonstrated in untreated mouse LTA cells during probing of immunoblots with C-2-10 monoclonal anti-PARP antibody. The source of the labeling was traced to the secondary antibody preparation, which labeled a Mr approximately 89000 polypeptide in murine LTA cells but not in human cells. These observations indicate that assessment of PARP cleavage must be (1) performed with appropriate controls when new cell lines are investigated and (2) carefully interpreted in light of additional biochemical or morphological data demonstrating apoptotic changes.
Mol Cell Biochem 1998 Jan
PMID:Apparent cleavage of poly(ADP-ribose) polymerase in non-apoptotic mouse LTA cells: an artifact of cross-reactive secondary antibody. 954 6

The binding site for the acceptor substrate poly(ADP-ribose) in the elongation reaction of the ADP-ribosyl transferase poly(ADP-ribose) polymerase (PARP) was detected by cocrystallizing the enzyme with an NAD+ analogue. The site was confirmed by mutagenesis studies. In conjunction with the binding site of the donor NAD+, the bound acceptor reveals the geometry of the elongation reaction. It shows in particular that the strictly conserved glutamate residue of all ADP-ribosylating enzymes (Glu988 of PARP) facilitates the reaction by polarizing both, donor and acceptor. Moreover, the binding properties of the acceptor site suggest a mechanism for the branching reaction, that also explains the dual specificity of this transferase for elongation and branching, which is unique among polymer-forming enzymes.
J Mol Biol 1998 Apr 24
PMID:The mechanism of the elongation and branching reaction of poly(ADP-ribose) polymerase as derived from crystal structures and mutagenesis. 957 Oct 33

Poly(ADP-ribose) polymerase (PARP; EC 2.4.2.30) is a zinc-finger DNA-binding protein that detects and signals DNA strand breaks generated directly or indirectly by genotoxic agents. In response to these breaks, the immediate poly(ADP-ribosyl)ation of nuclear proteins involved in chromatin architecture and DNA metabolism converts DNA damage into intracellular signals that can activate DNA repair programs or cell death options. To have greater insight into the physiological function of this enzyme, we have used the two-hybrid system to find genes encoding proteins putatively interacting with PARP. We have identified a physical association between PARP and the base excision repair (BER) protein XRCC1 (X-ray repair cross-complementing 1) in the Saccharomyces cerevisiae system, which was further confirmed to exist in mammalian cells. XRCC1 interacts with PARP by its central region (amino acids 301 to 402), which contains a BRCT (BRCA1 C terminus) module, a widespread motif in DNA repair and DNA damage-responsive cell cycle checkpoint proteins. Overexpression of XRCC1 in Cos-7 or HeLa cells dramatically decreases PARP activity in vivo, reinforcing the potential protective function of PARP at DNA breaks. Given that XRCC1 is also associated with DNA ligase III via a second BRCT module and with DNA polymerase beta, our results provide strong evidence that PARP is a member of a BER multiprotein complex involved in the detection of DNA interruptions and possibly in the recruitment of XRCC1 and its partners for efficient processing of these breaks in a coordinated manner. The modular organizations of these interactors, associated with small conserved domains, may contribute to increasing the efficiency of the overall pathway.
Mol Cell Biol 1998 Jun
PMID:XRCC1 is specifically associated with poly(ADP-ribose) polymerase and negatively regulates its activity following DNA damage. 958 96

Apoptosis and its augmentation by androgen withdrawal is an important event in the testis. In other tissues apoptosis is regulated by genes belonging to the bcl-2 family. However, little is known about these pathways in the human testes. Human testes were obtained from patients with prostate cancer, undergoing orchidectomy for permanent androgen ablative treatment. The patients were either untreated or had previously received short- or long-term anti-androgen therapy by cyproterone acetate or GnRH agonist (goserelin). In comparison with untreated patients, testicular testosterone concentrations were reduced by 83% in patients treated with cyproterone acetate and by 99% in patients treated with goserelin. Apoptotic cells were identified in tissue sections by in-situ end labelling of fragmented DNA. The expression of Bcl-2, Bcl-xl, Bax, p53 and poly(ADP) ribose polymerase (PARP) was demonstrated in tissue extracts by Western blotting. Apoptotic germ cells were present in the spermatogenic epithelium of untreated patients and patients who received short-term anti-androgen treatment. There were few or no apoptotic cells in the seminiferous tubules following long-term anti-androgen treatment. Following short-term treatment, the concentrations of the apoptosis-related proteins examined did not change. However, in the long-term treated testes, Bcl-xl and PARP expression declined, Bax and p53 protein concentrations were unchanged, and Bcl-2 was up-regulated. In conclusion, apoptosis occurs in spermatogenic cells of the human testis and may contribute to the regulation of germ cell populations. The apoptosis-related gene products which have been described in other tissues are present in the human testis and are modulated by androgenic stimuli.
Mol Hum Reprod 1998 Jul
PMID:Apoptosis and expression of apoptotic regulators in the human testis following short- and long-term anti-androgen treatment. 970 93

We have presently determined the effect of inhibition of the DNA repair enzyme poly(ADP-ribose) polymerase (PARP) on the occurrence of apoptosis in insulin-producing cells. The ADP-ribosylation activities of intact cells were decreased by incubation of RINm5F cells for 16 h with the PARP inhibitors nicotinamide (NA) (20-50 mM) or 3-aminobenzamide (3-ABA) (10 mM). Exposure to 20-50 mM NA or 10 mM 3-ABA both resulted in massive apoptosis in RINm5F cells. A 24 h exposure to 50 mM nicotinamide induced apoptosis in fetal but not adult rat islet cells. In addition, exposure of RINm5F cells to 50 mM NA for 12-24 h induced the appearance of the 85 kDa proteolytic PARP fragment, indicating activation of the ICE-like protease caspase-3. Incubation with 20-50 mM NA did not induce any consistent effects upon transcription factor NF-kappaB activity, demonstrating that this pathway is not involved in induction of apoptosis by NA. It is concluded that in insulin-producing cells with a high mitotic rate, inhibition of ADP-ribosylation--and consequently of auto-modification and release of PARP bound to DNA strand breaks--leads to activation of programmed cell death.
Mol Cell Endocrinol 1998 Apr 30
PMID:Nicotinamide-induced apoptosis in insulin producing cells is associated with cleavage of poly(ADP-ribose) polymerase. 970 78

The requirement for caspases (ICE-like proteases) were investigated in mediating apoptosis of WEHI7.2 mouse lymphoma cells in response to two death inducers with different mechanisms of action, the glucocorticoid hormone dexamethasone (DX) and the calcium-ATPase inhibitor thapsigargin (TG). Apoptosis induction by these agents followed different kinetics, and was closely correlated with in vivo activation of caspase-3 (CPP32/Yama/Apopain) and cleavage of the caspase target protein poly(ADP-ribose) polymerase (PARP). Caspase activation and PARP cleavage were inhibited by Bcl-2 overexpression. Cell extracts from DX- and TG-treated cells cleaved the in vitro synthesized baculovirus p35 ICE-like protease target, producing 25 and 10 kDa fragments. p35 cleavage was inhibited by mutating the active site aspartic acid to alanine, and by a panel of protease inhibitors that inhibit caspase-3-like proteases, including iodoacetamide, N-ethylmaleimide, and Ac-DEVD-cho. Treatment of cells in vivo with two cell permeant peptide fluoromethylketone inhibitors of caspase activity, Z-VAD-fmk and Z-DEVD-fmk, inhibited DX- and TG-induced apoptotic nuclear changes and maintained plasma membrane integrity, whereas the cathepsin inhibitor, Z-FA-fmk, and two calpain inhibitors failed to inhibit apoptosis. An unexpected observation was that due to the delayed time course of DX-induced apoptosis, optimal preservation of plasma membrane integrity was achieved by adding caspase inhibitors beginning 8 h after DX addition. In summary, the findings indicate that two diverse apoptosis-inducing signals converge into a common Bcl-2-regulated pathway that leads to caspase activation and apoptosis.
Mol Cell Endocrinol 1998 Apr 30
PMID:Apoptosis induction by the glucocorticoid hormone dexamethasone and the calcium-ATPase inhibitor thapsigargin involves Bc1-2 regulated caspase activation. 970 90

Poly(ADP-ribose) polymerase (PARP) is a DNA-binding protein involved in cellular response to various genotoxic agents. To understand the role of PARP in the mechanisms which lead from specific DNA damage to cell death, we studied the effects of PARP inhibition in human lymphoblasts damaged with bleomycin (BLM) and VP16. These agents can induce DNA breakage but through different mechanisms, enabling the study of the different effects of PARP in inducing apoptosis in damaged cells. We demonstrate that in lymphoblasts VP16 treatment induces apoptosis to a greater extent than BLM treatment, and that PARP inhibition reduces VP16-induced apoptosis whereas it has no effect on BLM-induced apoptosis. After VP16 treatment with PARP inhibition, a reduction in the depletion of the proliferative compartment and a G2/M phase arrest are observed. Therefore, the increase in cell viability and the reduction in chromosome damage may both be the result of a prolonged DNA repair time. Hence, PARP appears to play a significant role in VP16-induced apoptosis and not in BLM-induced apoptosis. Since apoptosis is important in tumor treatment these findings might be useful when considering the combined employment of PARP inhibition with antineoplastic drugs.
Environ Mol Mutagen 1998
PMID:Effects of poly(ADP-ribose) polymerase inhibition on cell death and chromosome damage induced by VP16 and bleomycin. 970 99

C2-ceramide, a cell-permeable analogue of ceramide, induced significant, dose- and time-dependent death in human retinoblastoma Y79 cells. Dying cells strongly displayed the morphology of apoptosis as characterized by microscopic evidence of cell shrinkage, membrane blebbing, nuclear and chromatin condensation and degeneration of the nucleus into membrane-bound apoptotic bodies. Upon induction of apoptosis Y79 cells evidence early phosphatidylserine externalization, as shown by annexin V-FITC. Apoptosis was also assessed by monitoring changes in cell granularity by staining with the combined fluorescent dyes acridine orange and ethidium bromide. C2-ceramide induced these morphological changes without a concomitant production of oligonucleosomal fragments responsible for the DNA ladder and without changes in p53 protein level. Apoptosis was accompanied by accumulation of a modified Bcl-2 protein with a slower-mobility form, and by proteolytic cleavage of PARP. The effect seemed to be specific for C2-ceramide, as C2-dihydroceramide, or other amphiphilic lipid analogues, or products of ceramide hydrolysis were ineffective. The effect also depended on mRNA and protein synthesis as it was markedly inhibited by actinomycin D and cycloheximide. Sphingomyelinase and interleukin-1beta, which are known to activate the sphingomyelin turnover leading to ceramide generation, also induced apoptosis mimicking the effects of ceramide. These findings propose ceramide as an activator of the suicidal program in Y79 cells.
Mol Cell Biochem 1998 Aug
PMID:Induction of programmed cell death in human retinoblastoma Y79 cells by C2-ceramide. 974 6

We report a new detection method for the purification of poly(ADP-ribose) polymerase (PARP). PARP purification generates many fractions in which PARP is usually detected by a time consuming activity assay. The development of a new method was also needed in order to decrease the utilization of radioactivity. This new method, based on an enzyme-linked immunosorbent assay (ELISA), is very rapid, sensitive, and avoids most radioactivity. Moreover, to illustrate this method, a new matrix was used, the Heparin Sepharose. This matrix was chosen for its affinity for the DNA binding proteins and because it allows the separation of whole PARP from its proteolytic fragments.
Mol Cell Biochem 1998 Aug
PMID:Rapid detection of poly(ADP-ribose) polymerase by enzyme-linked immunosorbent assay during its purification and improvement of its purification. 974 27

Trypanosoma brucei undergoes dramatic stage-specific changes in surface antigen expression, metabolic development, cellular morphogenesis and cell-cycle control. These events can be studied in detail during the transition between the bloodstream stumpy stage and the tsetse fly midgut procyclic form. This differentiation can be induced in vitro, is synchronous in the population and there are abundant markers for stage-regulated and differentiation events. We have used this differentiation system to investigate the role of de novo transcription during different phases of this well-characterised cellular transformation. Our experiments implicate early transcriptional involvement in shedding of the variable surface glycoprotein coat, cell restructuring and cell-cycle re-entry. The synchrony of differentiation has also been exploited to identify transcripts which define distinct regulated processes during this differentiation. The transcripts identified provide good coverage of the different molecular regulation events that accompany this life-cycle transformation. These included a surface antigen gene (encoding procyclin/PARP), a cell cycle regulated component (encoding histone H2B), a homologue of the Leishmania activated protein kinase C receptor (LACK) and a putative gene for sub unit VI of cytochrome c oxidase.
Mol Biochem Parasitol 1998 Sep 01
PMID:Identification of stage-regulated and differentiation-enriched transcripts during transformation of the African trypanosome from its bloodstream to procyclic form. 976 91


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>