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)

The concerted action of poly(ADP-ribose) polymerase (PARP) which synthesizes the poly(ADP-ribose) (pADPr) in response to DNA strand breaks and the catabolic enzyme poly(ADP-ribose) glycohydrolase (PARG) determine the level of polymer and the rate of its turnover. In the present study, we have shown that the quail myoblast cells have high levels of basal polymer as compared to the murine C3H10T1/2 fibroblasts. We have conducted this study to investigate how such differences influence polymer synthesis and its catabolism in the cells in response to DNA damage by alkylating agent. In quail myoblast cells, the presence of high MNNG concentration such as 200 microM for 30 min induced a marginal decrease of 15% in the NAD content. For C3H10T1/2 cell line, 64 microM MNNG provoked a depletion of NAD content by approximately 50%. The induction of the polymer synthesis in response to MNNG treatment was 6-fold higher in C3H10T1/2 cells than in quail myoblast cells notwithstanding the fact that 3-fold higher MNNG concentration was used for quail cells. The polymer synthesis thus induced in quail myoblast cells had a 4-5 fold longer half life than those induced in C3H10T1/2 cells. To account for the slow turnover of the polymer in the quail myoblast cells, we compared the activities of the polymer catabolizing enzyme (PARG) in the two cell types. The quail myoblast cells had about 25% less activity of PARG than the murine cells. This difference in activity is not sufficient to explain the large difference of the rate of catabolism between the two cell types implicating other cellular mechanisms in the regulation of pADPr turnover.
Mol Cell Biochem 1999 Mar
PMID:Poly(ADP-ribose) turnover in quail myoblast cells: relation between the polymer level and its catabolism by glycohydrolase. 1033 49

To elucidate the biological functions of poly(ADP-ribose) polymerase (PARP, [EC 2.4.2.30]) in DNA damage responses, genetic and biochemical approaches were undertaken. By disrupting exon 1 of the mouse PARP gene by a homologous recombination, PARP-deficient mouse embryonic stem (ES) cell lines and mice could be produced without demonstrating lethality. PARP-/- ES cells showed complete loss of PARP activity and increased sensitivity to gamma-irradiation and an alkylating agents, indicating a physiological role for PARP in the response to DNA damage. p53, a key molecule in cellular DNA damage response, was found to stimulate PARP activity and became poly(ADP-ribosyl)ated in the presence of damaged DNA. However, PARP-/- ES cells showed p21 and Mdm-2 mRNA induction following gamma-irradiation, indicating that PARP activity is not indispensable for p21 and Mdm-2 mRNA induction in the established p53-cascade. On the other hand, in a reconstituted reaction system, purified PARP from human placenta suppressed the pRB-phosphorylation activity in the presence of NAD and damaged DNA. Human PARP expressed in E. coli showed a similar effect on pRB-phosphorylation activity of cdk2. These findings suggest a direct involvement of PARP in the regulation of cdk activity for cell-cycle arrest.
Mol Cell Biochem 1999 Mar
PMID:Function of poly(ADP-ribose) polymerase in response to DNA damage: gene-disruption study in mice. 1033 51

We have focused on the roles of PARP and poly(ADP-ribosyl)ation early in apoptosis, as well as during the early stages of differentiation-linked DNA replication. In both nuclear processes, a transient burst of PAR synthesis and PARP expression occurs early, prior to internucleosomal DNA cleavage before commitment to apoptosis as well as at the round of DNA replication prior to the onset of terminal differentiation. In intact human osteosarcoma cells undergoing spontaneous apoptosis, both PARP and PAR decreased after this early peak, concomitant with the inactivation and cleavage of PARP by caspase-3 and the onset of substantial DNA and nuclear fragmentation. Whereas 3T3-L1, osteosarcoma cells, and immortalized PARP +/+ fibroblasts exhibited this early burst of PAR synthesis during Fas-mediated apoptosis, neither PARP-depleted 3T3-L1 PARP-antisense cells nor PARP -/- fibroblasts showed this response. Consequently, whereas control cells progressed into apoptosis, as indicated by induction of caspase-3-like PARP-cleavage activity, PARP-antisense cells and PARP -/- fibroblasts did not, indicating a requirement for PARP and poly(ADP-ribosyl)ation of nuclear proteins at an early reversible stage of apoptosis. In parallel experiments, a transient increase in PARP expression and activity were also noted in 3T3-L1 preadipocytes 24 h after induction of differentiation, a stage at which approximately 95% of the cells were in S-phase, but not in PARP-depleted antisense cells, which were consequently unable to complete the round of DNA replication required for differentiation. PARP, a component of the multiprotein DNA replication complex (MRC) that catalyzes viral DNA replication in vitro, poly(ADP-ribosyl)ates 15 of approximately 40 MRC proteins, including DNA pol alpha, DNA topo I, and PCNA. Depletion of endogenous PARP by antisense RNA expression in 3T3-L1 cells results in MRCs devoid of any DNA pol alpha and DNA pol delta activities. Surprisingly, there was no new expression of PCNA and DNA pol alpha, as well as the transcription factor E2F-1 in PARP-antisense cells during entry into S-phase, suggesting that PARP may play a role in the expression of these proteins, perhaps by interacting with a site in the promoters for these genes.
Mol Cell Biochem 1999 Mar
PMID:Involvement of PARP and poly(ADP-ribosyl)ation in the early stages of apoptosis and DNA replication. 1033 50

Activation of poly(ADP-ribose) polymerase (PARP) by DNA breaks catalyzes poly(ADP-ribosyl)ation and results in depletion of NAD+ and ATP, which is thought to induce necrosis. Proteolytic cleavage of PARP by caspases is a hallmark of apoptosis. To investigate whether PARP cleavage plays a role in apoptosis and in the decision of cells to undergo apoptosis or necrosis, we introduced a point mutation into the cleavage site (DEVD) of PARP that renders the protein resistant to caspase cleavage in vitro and in vivo. Here, we show that after treatment with tumor necrosis factor alpha, fibroblasts expressing this caspase-resistant PARP exhibited an accelerated cell death. This enhanced cell death is attributable to the induction of necrosis and an increased apoptosis and was coupled with depletion of NAD+ and ATP that occurred only in cells expressing caspase-resistant PARP. The PARP inhibitor 3-aminobenzamide prevented the NAD+ drop and concomitantly inhibited necrosis and the elevated apoptosis. These data indicate that this accelerated cell death is due to NAD+ depletion, a mechanism known to kill various cell types, caused by activation of uncleaved PARP after DNA fragmentation. The present study demonstrates that PARP cleavage prevents induction of necrosis during apoptosis and ensures appropriate execution of caspase-mediated programmed cell death.
Mol Cell Biol 1999 Jul
PMID:Failure of poly(ADP-ribose) polymerase cleavage by caspases leads to induction of necrosis and enhanced apoptosis. 1037 61

The enhanced expression of the RI alpha subunit of cyclic AMP-dependent protein kinase type 1 (PKA-1) has been correlated with cancer cell growth. We have investigated the effects of sequence-specific inhibition of RI alpha gene expression on the growth of MCF-7 human breast cancer cells. We report that RI alpha antisense treatment results in a reduction in RI alpha expression at both mRNA and protein levels and inhibition of cell growth. The growth inhibition was accompanied by changes in cell morphology, cleavage of poly(ADP-ribose) polymerase (PARP) and appearance of apoptotic nuclei. In addition, bcl-2 protein level was reduced and p53 expression increased in growth arrested cells. Interestingly, RI alpha antisense inhibited cell viability and induced apoptosis in the absence of p53, suggesting that these actions of RI alpha antisense are exerted independent of p53. In contrast, two- and four-base mismatched control oligonucleotides had no effect on either cell growth or morphology. These results demonstrate that the RI alpha antisense, which efficiently depletes the growth stimulatory molecule RI alpha, induces cell differentiation and apoptosis, providing a new approach to combat breast cancer cell growth.
Mol Cell Biochem 1999 May
PMID:Growth arrest and induction of apoptosis in breast cancer cells by antisense depletion of protein kinase A-RI alpha subunit: p53-independent mechanism of action. 1039 66

Escherichia coli heat-labile enterotoxin (LT) is composed of catalytic A and non-catalytic homo-pentameric B subunits and causes diarrheal disease in human and animals. In order to produce a nontoxic LT for vaccine and adjuvant development, two novel derivatives of LT were constructed by a site-directed mutagenesis of A subunit; Ser63 to Tyr63 in LTS63Y and Glu110, Glu112 were deleted in LT delta 110/112. The purified mutant LTs (mLTs) showed a similar molecular structural complex as AB5 to that of wild LT. In contrast to wild-type LT, mLTs failed to induce either elongation activity, ADP-ribosyltransferase activity, cAMP synthesis in CHO cells or fluid accumulation in mouse small intestine in vivo. Mice immunized with mLTs either intragastrically or intranasally elicited high titers of LT-specific serum and mucosal antibodies comparable to those induced by wild-type LT. These results indicate that substitution of Ser63 to Tyr63 or deletion of Glu110 and Glu112 eliminate the toxicity of LT without a change of AB5 conformation, and both mutants are immunogenic to LT itself. Therefore, both mLTs may be used to develop novel anti-diarrheal vaccines against enterotoxigenic E. coli.
Exp Mol Med 1999 Jun 30
PMID:Development of two novel nontoxic mutants of Escherichia coli heat-labile enterotoxin. 1041 Mar 10

The retinoblastoma tumor suppressor protein (RB) has been shown to play a role in regulating the eukaryotic cell cycle, promoting cellular differentiation, and modulating programmed cell death. Although regulation of RB tumor suppressor activity is mediated by reversible phosphorylation, an additional posttranslational modification involves the cleavage of 42 residues from the carboxy terminus of RB during the onset of drug-induced or receptor-mediated apoptosis. We now demonstrate that a recombinant p100cl RB species localizes to the nucleus where it may retain wildtype "pocket" protein binding activity. In addition, using immunocytochemistry, we show that cleavage of the endogenous RB protein occurs in vivo in human cells and that p100cl is predominantly retained within the nuclear compartment of cells during early apoptosis. We also show that the carboxy-terminal cleavage of RB is detected immediately following caspase-3 and PARP cleavage during FAS-mediated apoptosis of MCF10 cells. These findings suggest that this cleavage event may be a component of a downstream cascade during programmed cell death.
Mol Cell Biol Res Commun 1999 Jun
PMID:The 100-kDa proteolytic fragment of RB is retained predominantly within the nuclear compartment of apoptotic cells. 1042 29

Rho, a member of the Rho small G protein family, regulates the formation of stress fibers and focal adhesions in various types of cultured cells. We investigated here the actions of ROCK and mDia, both of which have been identified to be putative downstream target molecules of Rho, in Madin-Darby canine kidney cells. The dominant active mutant of RhoA induced the formation of parallel stress fibers and focal adhesions, whereas the dominant active mutant of ROCK induced the formation of stellate stress fibers and focal adhesions, and the dominant active mutant of mDia induced the weak formation of parallel stress fibers without affecting the formation of focal adhesions. In the presence of C3 ADP-ribosyltransferase for Rho, the dominant active mutant of ROCK induced the formation of stellate stress fibers and focal adhesions, whereas the dominant active mutant of mDia induced only the diffuse localization of actin filaments. These results indicate that ROCK and mDia show distinct actions in reorganization of the actin cytoskeleton. The dominant negative mutant of either ROCK or mDia inhibited the formation of stress fibers and focal adhesions, indicating that both ROCK and mDia are necessary for the formation of stress fibers and focal adhesions. Moreover, inactivation and reactivation of both ROCK and mDia were necessary for the 12-O-tetradecanoylphorbol-13-acetate-induced disassembly and reassembly, respectively, of stress fibers and focal adhesions. The morphologies of stress fibers and focal adhesions in the cells expressing both the dominant active mutants of ROCK and mDia were not identical to those induced by the dominant active mutant of Rho. These results indicate that at least ROCK and mDia cooperatively act as downstream target molecules of Rho in the Rho-induced reorganization of the actin cytoskeleton.
Mol Biol Cell 1999 Aug
PMID:Distinct actions and cooperative roles of ROCK and mDia in Rho small G protein-induced reorganization of the actin cytoskeleton in Madin-Darby canine kidney cells. 1043 6

We have investigated the possibility of the involvement of PARP in apoptosis, independently of its enzymatic activity. We thus transfected PARP(-)/(-)A11 cells with a DNA construct encoding the PARP DNA-binding domain (DBD) fragment or mutants DBDbd(-), defective in DNA binding to DNA strand breaks, and DBDcl(-), resistant to caspase-3 cleavage. We found that in the absence of PARP, while expression of DBD has only a marginal effect, expression of the mutants strongly inhibits the apoptosis induced by staurosporine, as measured by the binding of annexin V. Moreover, the mutants, but not DBD, inhibit the cleavage of DNA PKcs, suggesting inhibition of activation of caspase-3. In addition, the mutant transfectants are fractionally less susceptible to low doses of an alkylating agent than the DBD transfectant or the original A11 line. The results suggest that the DBD fragment of PARP, apart from its classical role of nick detection and DNA binding, participates in complexes involved in upstream events leading to activation of the caspase cascade.
J Mol Biol 1999 Jul 30
PMID:Inhibition of apoptosis of a PARP(-)/(-)cell line transfected with PARP DNA-binding domain mutants. 1043 94

The steady-state levels of mRNA for the poly(ADP-ribose)polymerase (PARP), c-myc, p53, and histone H3 genes were investigated in 31 high-grade B-cell lymphomas by northern blot analysis. The panel included 15 nodal large B-cell lymphomas, nine mediastinal large B-cell lymphomas, and seven sporadic Burkitt's lymphomas. The PARP mRNA level was significantly higher in lymphomas than in control tissues and corresponded with the amount of PARP protein, as assessed by immunoblot analysis in six samples. The level of PARP mRNA was positively correlated with that of p53 mRNA. No correlation was found between the mRNA expression levels of PARP and histone H3, suggesting that PARP expression levels are independent of the proliferation rate of neoplastic cells. In this setting, the strong correlation between PARP and p53 suggests that the high expression of PARP may be associated with ongoing DNA damage in high-grade lymphomas.
Mol Carcinog 1999 Aug
PMID:Correlation of poly(ADP-ribose)polymerase and p53 expression levels in high-grade lymphomas. 1044 32


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