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PubMed2004

Using 31P NMR spectroscopy at 14.1 Tesla to investigate PARP-1 associated energy failure and metabolic rescue in cerebrocortical slices.

PARP-1 activation by H(2)O(2) in an acute preparation of superfused, respiring, neonatal cerebrocortical slices was assessed from PAR-polymer formation detected with immunohistochemistry and Western blotting. (31)P NMR spectroscopy at 14.1 Tesla of perchloric acid slice extracts was used to assess energy failure in a 1-h H(2)O(2) exposure as well as in a subsequent 4-h recovery period where the superfusate had no H(2)O(2) and specifically chosen metabolic substrates. Although more data are needed to fully characterize different bioenergetic responses, a high NMR spectral resolution (PCr full-width at half-max approximately.01 ppm) and narrow widths for most metabolites (<.2 ppm) permitted accurate quantifications of spectrally resolved resonances for ADP, ATP, NAD(+)/NADH, and other high energy phosphates. It appears possible to use brain slices to quantitatively study PARP-related, NAD-associated energy failure, and rescue with TCA metabolites.

Animals↗
PubMed2004

Inhibition of TRPM2 function by PARP inhibitors protects cells from oxidative stress-induced death.

TRPM2 is a member of the transient receptor potential (TRP) protein superfamily of calcium-permeable, voltage-independent ion channels expressed in nonexcitable cells. Activation of TRPM2 by oxidative stress results in calcium influx and susceptibility to cell death, whereas inhibition of TRPM2 function enhances cell survival. In the present edition of this journal, Fonfria et al. demonstrate a role for poly(ADP ribose) polymerase (PARP) as a mediator between oxidative stress and TRPM2 activation. They present evidence that inhibition of either PARP or TRPM2 protects cells from plasma membrane damage and cell death. The therapeutic implications of this important observation are discussed.

Calcium↗
PubMedDate not supplied

Gene/longevity association studies at four autosomal loci (REN, THO, PARP, SOD2).

The possibility that four loci (REN, THO, PARP, SOD2) are associated with longevity was explored by comparing the genotypic pools of subjects older than 100 years with those of younger subjects matched for sex and geographic area (northern and southern Italy). The markers (all located within the respective gene) were HUMREN4; HUMTHO1; HUMPARP (gt)845nt; SOD2(C/T)401nt. In order to reduce the number of genotypes, multiallelic polymorphisms were recoded as diallelic according to allele size and frequency patterns (small: S, and large: L, alleles). A significant loss of LL homozygous genotypes was found at the THO locus in male but not in female centenarians with respect to matched controls. On the other hand no significant difference was found between case/control genotypic frequencies at REN, PARP, SOD2 loci. The latter loci therefore do not affect inter-individual variability in life expectancy (at least in terms of qualitative variants associated with the tested markers). However, the data is consistent with an association between the THO locus and longevity.

Adolescent↗
PubMed1992

The PARP and VSG genes of Trypanosoma brucei do not resemble RNA polymerase II transcription units in sensitivity to Sarkosyl in nuclear run-on assays.

Addition of the ionic detergent N-lauroylsarcosine (Sarkosyl) affects the efficiency of transcription of genes of the protozoan Trypanosoma brucei in nuclear run-on assays. Transcription of the PARP (procyclin or procyclic acidic repetitive protein), variant cell surface glycoprotein (VSG) and ribosomal RNA (rRNA) genes was resistant or increased after addition of Sarkosyl. In contrast, the transcription of seven protein coding house keeping genes and the mini-exon donor RNA (medRNA) genes was completely abolished by the addition of Sarkosyl, while the transcription of the 5S rRNA genes showed an intermediate sensitivity. We conclude that Sarkosyl can be used to discriminate between the different types of trypanosome transcription units. The PARP and VSG protein coding genes had previously been postulated to be transcribed by an RNA polymerase I-like enzyme on the basis of their resistance to the RNA polymerase II inhibitor alpha-amanitin. This model is now supported by their resistance to the addition of Sarkosyl.

Animals↗
PubMed1996

BCL-2 delay apoptosis and PARP cleavage induced by NO donors in GT1-7 cells.

BCL-2 is a negative regulator of cell death in several systems. Here we report that bcl-2 expression protects against apoptosis induced by nitric oxide (NO) donors in GT1-7 hypothalamic cells. BCL-2 significantly inhibited neuronal death caused by 200 microM S-nitroso-cysteine (SNOC), 200 microM S-nitroso-N-acetyl-penicillamine (SNAP), or 1 mM 3-morpholinosydnonimine (SIN-1). To explore further the protective mechanism(s) elicited by bcl-2 expression, we investigated whether BCL-2 could prevent NO-induced cleavage of poly-ADP-ribose-polymerase (PARP), which is a substrate for interleukin-1 beta converting enzyme (ICE)-like proteases in apoptosis. Formation of 85 and 25 kDa PARP fragments elicited by NO donors was inhibited in cells over-expressing bcl-2.

Apoptosis↗
PubMed2004

The expression of PARP, NF-kappa B and parvalbumin is increased in Parkinson disease.

Immunohistochemical techniques revealed a significant increase of poly(ADP-ribose) polymerase (PARP)-containing nuclei in the dopaminergic neurons of the substantia nigra (SN) in Parkinson disease and in diffuse Lewy body disease as compared with a group of patients with other neurodegenerative diseases and normal controls. The nuclear translocation of nuclear factor kappa B (NF-kappa B) was also noted in the same cells. The over-activation of PARP and the transcriptional activation of NF-kappa B can contribute to the pathomechanism of the disease specific lesion of the neurons in the SN. However, in another subgroup of dopaminergic cells of the SN an increased parvalbumin content was detected reflecting a natural protective mechanism against the putative increase of intracellular calcium caused by excitotoxic injury and oxidative stress.

Humans↗
PubMed2003

Chromatin loosening by poly(ADP)-ribose polymerase (PARP) at Drosophila puff loci.

Steroid response and stress-activated genes such as hsp70 undergo puffing in Drosophila larval salivary glands, a local loosening of polytene chromatin structure associated with gene induction. We find that puffs acquire elevated levels of adenosine diphosphate (ADP)-ribose modified proteins and that poly(ADP)-ribose polymerase (PARP) is required to produce normal-sized puffs and normal amounts of Hsp70 after heat exposure. We propose that chromosomal PARP molecules become activated by developmental or environmental cues and strip nearby chromatin proteins off DNA to generate a puff. Such local loosening may facilitate transcription and may transiently make protein complexes more accessible to modification, promoting chromatin remodeling during development.

Animals↗
PubMed1996

Characterization of a transcription terminator of the procyclin PARP A unit of Trypanosoma brucei.

The polycistronic procylcin PARP (for procyclic acidic repetitive protein) A transcription unit of Trypanosoma brucei was completely characterized by the mapping of the termination region. In addition to the tandem of procyclin genes and GRESAG 2.1, this 7.5- to 9.5-kb unit contained another gene for a putative surface protein, termed PAG (for procyclin-associated gene) 3. The terminal 3-kb sequence did not contain significant open reading frames and cross-hybridized with the beginning of one or several transcription units specific to the bloodstream form. At least three separate fragments from the terminal region were able to inhibit chloramphenicol acetyltransferase expression when inserted between either the PARP, the ribosomal, or the variable surface glycoprotein promoter and a chloramphenicol acetyltransferase reporter gene. This inhibition was due to an orientation-dependent transcription termination caused by the combination of several attenuator elements with no obvious sequence conservation. The procyclin transcription terminator appeared unable to inhibit transcription by polymerase II.

Amino Acid Sequence↗
PubMed2005

TRPM2 is an ion channel that modulates hematopoietic cell death through activation of caspases and PARP cleavage.

TRPM2 is a Ca(2+)-permeable channel activated by oxidative stress or TNF-alpha, and TRPM2 activation confers susceptibility to cell death. The mechanisms were examined here in human monocytic U937-ecoR cells. This cell line expresses full-length TRPM2 (TRPM2-L) and several isoforms including a short splice variant lacking the Ca(2+)-permeable pore region (TRPM2-S), which functions as a dominant negative. Treatment with H(2)O(2), a model of oxidative stress, or TNF-alpha results in reduced cell viability. Expression of TRPM2-L and TRPM2-S was modulated by retroviral infection. U937-ecoR cells expressing increased levels of TRPM2-L were treated with H(2)O(2) or TNF-alpha, and these cells exhibited significantly increased intracellular calcium concentration ([Ca(2+)](i)), decreased viability, and increased apoptosis. A dramatic increase in cleavage of caspases-8, -9, -3, and -7 and poly(ADP-ribose)polymerase (PARP) was observed, demonstrating a downstream mechanism through which cell death is mediated. Bcl-2 levels were unchanged. Inhibition of the [Ca(2+)](i) rise with the intracellular Ca(2+) chelator BAPTA blocked caspase/PARP cleavage and cell death induced after activation of TRPM2-L, demonstrating the critical role of [Ca(2+)](i) in mediating these effects. Downregulation of endogenous TRPM2 by RNA interference or increased expression of TRPM2-S inhibited the rise in [Ca(2+)](i), enhanced cell viability, and reduced numbers of apoptotic cells after exposure to oxidative stress or TNF-alpha, demonstrating the physiological importance of TRPM2. Our data show that one mechanism through which oxidative stress or TNF-alpha mediates cell death is activation of TRPM2, resulting in increased [Ca(2+)](i), followed by caspase activation and PARP cleavage. Inhibition of TRPM2-L function by reduction in TRPM2 levels, interaction with TRPM2-S, or Ca(2+) chelation antagonizes this important cell death pathway.

Alternative Splicing↗
PubMed2005

The sirtuin inhibitor nicotinamide enhances neuronal cell survival during acute anoxic injury through AKT, BAD, PARP, and mitochondrial associated "anti-apoptotic" pathways.

Understanding the role of nicotinamide (NIC) in different cell systems represents a significant challenge in several respects. Recently, NIC has been reported to have diverse roles during cell biology. In the absence of NIC, sirtuin protein activity is enhanced and pyrazinamidase/nicotinamidase 1 (PNC1) expression, an enzyme that deaminates NIC to convert NIC into nicotinic acid, is increased to lead to lifespan extension during calorie restriction, at least in yeast. Yet, NIC may be critical for cell survival as well as the modulation of inflammatory injury during both experimental models as well as in clinical studies. We therefore investigated some of the underlying signal transduction pathways that could be critical for the determination of the neuroprotective properties of NIC. We examined neuronal injury by trypan blue exclusion, DNA fragmentation, phosphatidylserine (PS) exposure, Akt1 phosphorylation, Bad phosphorylation, mitochondrial membrane potential, caspase activity, cleavage of poly(ADP-ribose) polymerase (PARP), and mitogen-activated protein kinases (MAPKs) phosphorylation. Application of NIC (12.5 mM) significantly increased neuronal survival from 38 -/+ 3% of anoxia treated alone to 68 +/- 3%, decreased DNA fragmentation and membrane PS exposure from 67 -/+ 4% and 61 -/+ 5% of anoxia treated alone to 30 +/- 4% and 26 +/- 4% respectively. We further demonstrate that NIC functions through Akt1 activation, Bad phosphorylation, and the downstream modulation of mitochrondrial membrane potential, cytochrome c release, caspase 1, 3, and 8 - like activities, and PARP integrity to prevent genomic DNA degradation and PS externalization during anoxia. Yet, NIC does not alter the activity of either the MAPKs p38 or JNK, suggesting that protection by NIC during anoxia is independent of the p38 and JNK pathways. Additional investigations targeted to elucidate the cellular pathways responsible for the ability of NIC to modulate both lifespan extension and cytoprotection may offer critical insight for the development of new therapies for nervous system disorders.

Animals↗
PubMed2001

The levels of MDM2 protein are decreased by a proteasome-mediated proteolysis prior to caspase-3-dependent pRb and PARP cleavages.

MDM2 is a substrate of caspase-3 in p53-mediated apoptosis. In addition, MDM2 mediates its own ubiquitination in a RING finger-dependent manner. Thus, we investigated whether MDM2 is degraded through a ubiquitin-dependent proteasome pathway in the absence of p53. When HL-60 cells, p53 null, were treated with etoposide, MDM2 was markedly decreased prior to caspase-3-dependent retinoblastoma tumor suppressor protein (pRb) and poly (ADP- ribose) polymerase (PARP) cleavages. Moreover, down-regulation of MDM2 level was not coupled with its mRNA down-regulation. However, the level of MDM2 was partially restored by proteasome inhibitors such as LLnL and lactacystin, even in the presence of etoposide. Our results suggest that, in the p53 null status, MDM2 protein level is decreased by proteasome-mediated proteolysis prior to caspase-3-dependent PARP and pRb cleavages.

Antineoplastic Agents, Phytogenic↗
PubMed2006

[Effect of ursolic acid on caspase-3 and PARP expression of human MCF-7 cells].

OBJECTIVE: To study the effect of ursolic acid (UA), apentacyclic triterpene acid, on MCF-7 cell apoptosis, and probable mechanism involved by detecting the expressions of caspase-3 and poly ADP-ribose polymerase(PARP) at protein level. METHOD: MCF-7 cells were cultured with different concentrations of UA. Growth inhibition of UA on MCF-7 cells was evaluated by MTT assay. Cell cycle and sub-G1 peak were performed by FCM. Morphologic changes of UA-treated cells were observed by light microscope. Apoptotic cells with condensed or fragmented nuclei were visualized by Ho 33258 staining by a fluorescence microscope (EX: U. V.). The protein expression of caspase-3 and PARP was analyzed by immunofluorescence cell staining (SABC-Cy3). RESULT: 24 hours after UA treatment, inhibition of MCF-7 cell growth was concentration-dependent. The IC50 value for UA was (22.6 +/- 3.0) micromo x L(-1). Cell cycle anaysis by FCM showed that 50 micromol x L(-1) of UA arrested MCF-7 cell cycle at G0 - G1 phase. Morphological changes of MCF-7 Cells exhibited many of the hallmark features of apoptosis, including chromatin clumps and aggregation and DNA fragmentation. UA increased caspase-3 protein expression. CONCLUSION: The results suggest that UA evokes MCF-7 cell apoptosis is correlation with the up-regulation of caspase-3. Our study indicated that UA might be a potential Chinese medical component for breast neoplasm.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Homoharringtonine mediates myeloid cell apoptosis via upregulation of pro-apoptotic bax and inducing caspase-3-mediated cleavage of poly(ADP-ribose) polymerase (PARP).

Homoharringtonine (HHT) is a plant alkaloid with antileukemia activity that is currently being used for treatment of acute, chronic leukemias and MDS. In this study, we show that HHT can induce apoptosis in a variety of human myeloid leukemia cell lines (U937, HL-60, HEL, THP, and K562). U937 and HL60 cells undergo rapid apoptosis on treatment with HHT, as indicated by increased annexin V binding capacity, caspase-3 activation, and cleavage of poly(ADP-ribose) polymerase (PARP). In addition, the expression of bax is upregulated during HHT-induced cell death, whereas the expression of bcl-2 is only slightly decreased. Importantly, treatment of primary leukemic cells, obtained from acute myeloid leukemia patients, resulted in rapid apoptosis. Thus, our data provide the mechanism of HHT and justify the use of HHT in the treatment of human myeloid leukemia.

Annexin A5↗
PubMed2007

Impact of copper on the induction and repair of oxidative DNA damage, poly(ADP-ribosyl)ation and PARP-1 activity.

Copper is an essential trace element involved, among other functions, in enzymatic antioxidative defense systems. However, nonprotein bound copper ions have been shown to generate reactive oxygen species. To gain insight into the discrepancy between the protective properties of copper on the one hand and its toxicity on the other hand, we examined the genotoxic effects of CuSO(4) in cultured human cells. Here we report that copper, at cytotoxic concentrations, induces oxidative DNA base modifications and DNA strand breaks. However, at lower noncytotoxic concentrations, copper inhibits the repair of oxidative DNA damage induced by visible light. As a first mechanistic hint, inhibition of H(2)O(2)-induced poly(ADP-ribosyl)ation was identified in cultured cells and further experiments demonstrated a strong inhibition of the activity of isolated poly(ADP-ribose)polymerase-1 (PARP-1) by copper. Bioavailability studies of copper showed a dose-dependent uptake in cells and pointed out the relevance of the applied concentrations. Taken together, the results indicate that copper, under conditions of either disturbed homeostasis or overload due to high exposure, exerts defined genotoxic effects. Hence, a balance needs to be maintained to ensure sufficient uptake and to prevent overload.

Copper↗
PubMed2007

[Reconstruction of a crushed chest with HI-TEX PARP NT implant].

The authors present the case of a 57-year-old man with polytrauma, who was injured in a train accident. Together with other injuries, he also sustained multiple comminuted fractures on the left half of the rib cage. These subsequently required surgical intervention because of thoracic instability and impending lung injury. Extensive damage to the thoracic skeleton was treated by removal of the damaged tissues and replacement by the HI-TEX PARP NT implant. The presented procedure is being discussed as an alternative to metallic fixation in thoracic instability in cases of devastating injury or injury resulting in bone and tissue loss.

Coated Materials, Biocompatible↗
PubMed2004

The discovery and synthesis of novel adenosine substituted 2,3-dihydro-1H-isoindol-1-ones: potent inhibitors of poly(ADP-ribose) polymerase-1 (PARP-1).

A series of novel 4-(N-acyl)-2,3-dihydro-1H-isoindol-1-ones have been prepared from methyl-3-nitro-2-methylbenzoate and linked through various spacers to the adenosine derivatives 11 and 12. We found that potent inhibition of poly(ADP-ribose)polymerase-1 (PARP-1) was achieved when isoindolinone was linked to adenosine by a spacer group of a specific length. Introduction of piperazine and succinyl linkers between the isoindolinone and adenosine core structures resulted in highly potent compounds 8a and 10b, which showed IC(50) values of 45 and 100 nM, respectively.

Adenosine↗
PubMed2005

Synthesis and structure-activity relationships of novel pyrrolocarbazole lactam analogs as potent and cell-permeable inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1).

A series of novel pyrrolocarbazole lactams was identified as potent PARP-1 inhibitors in vitro and in a PC12 cellular NAD(+) depletion assay. The SAR trends of substituents at the 3-position, as well as the effect of blocking the indole or lactam NH-groups of the template by methylation or formylation, are discussed in relation to molecular modeling studies.

Animals↗
PubMed2004

The ways of PARP.

Two papers in this issue of Cell describe two roles of poly(ADP-ribose) polymerase (PARP) in modulating chromatin structure: as a structural component replacing linker histone (Kim et al., 2004) and as a constituent of a corepressor complex poised to dismiss repression upon receipt of an activating signal (Ju et al., 2004).

Animals↗