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

One of the immediate reactions of the mammalian cell to many environmental stresses is a massive synthesis of poly(ADP-ribose), catalyzed by poly(ADP-ribose) polymerase (PARP). Most of the biological functions attributed to PARP are inferred from experimentation with mammalian cells. In plants, the biology of PARP may be more complicated and diverse than was previously thought. Two poly(ADP-ribose) polymerase homologues were found in plants, the classical Zn-finger-containing polymerase (ZAP) and the structurally non-classical PARP proteins (APP and NAP), which lack the characteristic N-terminal Zn-finger domain. By enzymatic and cytological experiments the recombinant APP protein was shown to be located in the nucleus and to possess DNA-dependent poly(ADP-ribose) polymerase activity in yeast. The nuclear localization was further confirmed by the analysis of transgenic tobacco plants that expressed a translational gene fusion between APP and the bacterial beta-glucuronidase. The app promoter was transcriptionally up-regulated in cells pre-determined to die because of deficiency in a DNA ligase I.
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PMID:Higher plants possess two structurally different poly(ADP-ribose) polymerases. 977 46

We previously reported that, in normal human epidermal keratinocytes (NHEK) cultures exposed to the alkylating compound sulfur mustard (bis-(2-chloroethyl) sulfide, HD, 0.3-1 mM), there is a rapid (< or =1 h) activation (100% above unexposed control) of the DNA repair enzyme DNA ligase I (130 kD) followed by a first-order decay (1-5 h). The DNA ligase activation is accompanied by a time-dependent (0.5-4 h) and significant DNA repair. Inhibition of another putative DNA repair enzyme, poly(ADP-ribose) polymerase (PARP), by using 3-amino benzamide does not affect DNA ligase activation following HD exposure, but increases the half-life of the activated enzyme threefold. To examine the role of PARP in HD-induced DNA ligase activation and subsequent DNA repair, we conducted studies using cultured keratinocytes in which the level of PARP had been selectively lowered (> or =85%) by the use of induced expression of antisense RNA. In these cells, there was no stimulation of DNA ligase up to 3 h, and a small stimulation (ca. 30% above unexposed control at 5-6 h after HD exposure. A time-course (0.5-6 h) study of DNA repair in HD-exposed PARP-deficient keratinocytes revealed a much slower rate of repair compared with HD-exposed NHEK. The results suggest an active role of PARP in DNA ligase activation and DNA repair in mammalian cells, and also indicate that modulation of PARP-mediated mechanisms may provide a useful approach in preventing HD toxicity.
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PMID:Role of poly(ADP-ribose) polymerase (PARP) in DNA repair in sulfur mustard-exposed normal human epidermal keratinocytes (NHEK). 1142 24

Three mammalian genes encoding DNA ligases--LIG1, LIG3, and LIG4--have been identified. Genetic, biochemical, and cell biology studies indicate that the products of each of these genes play a unique role in mammalian DNA metabolism. Interestingly, cell lines deficient in either DNA ligase I (46BR.1G1) or DNA ligase III (EM9) are sensitive to simple alkylating agents. One interpretation of these observations is that DNA ligases I and III participate in functionally distinct base excision repair (BER) subpathways. In support of this idea, extracts from both DNA ligase-deficient cell lines are defective in catalyzing BER in vitro and both DNA ligases interact with other BER proteins. DNA ligase I interacts directly with proliferating cell nuclear antigen (PCNA) and DNA polymerase beta (Pol beta), linking this enzyme with both short-patch and long-patch BER. In somatic cells, DNA ligase III alpha forms a stable complex with the DNA repair protein Xrcc1. Although Xrcc1 has no catalytic activity, it also interacts with Pol beta and poly(ADP-ribose) polymerase (PARP), linking DNA ligase III alpha with BER and single-strand break repair, respectively. Biochemical studies suggest that the majority of short-patch base excision repair events are completed by the DNA ligase III alpha/Xrcc1 complex. Although there is compelling evidence for the participation of PARP in the repair of DNA single-strand breaks, the role of PARP in BER has not been established.
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PMID:Completion of base excision repair by mammalian DNA ligases. 1155 94

The functional involvement of poly(ADP-ribose) polymerase-1 (PARP-1) in the repair of DNA single- and double-strand breaks, DNA base damage, and related repair substrate intermediates remains unclear. Using an in vitro DNA repair assay and cell extracts derived from PARP-1 deficient or wild-type murine embryonic fibroblasts, we investigated the DNA synthesis and ligation steps associated with the rejoining of DNA single-strand interruptions containing 3'-OH, and either 5'-OH or 5'-P termini. Complete repair leading to DNA rejoining was similar between PARP-1 deficient cells and wild-type controls and poly(ADP-ribose) synthesis was, as expected, greatly reduced in PARP-1 deficient cell extracts. The incorporation of [32P]dCMP into repaired DNA at the site of a lesion was reduced two-three-fold in PARP-1 deficient cell extracts, demonstrating a decrease in repair patch size. Addition of purified PARP-1 to levels approximating those present in wild-type extracts did not stimulate DNA repair synthesis. We conclude that PARP-1 is not required for the efficient processing and rejoining of single-strand interruptions with defined 3'-OH and 5'-OH or 5'-P termini. Decreased DNA repair synthesis observed in PARP-1 deficient cell extracts is associated with reduced cellular expression of several factors required for long-patch base excision repair (BER), including FEN-1 and DNA ligase I.
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PMID:Down-regulation of DNA repair synthesis at DNA single-strand interruptions in poly(ADP-ribose) polymerase-1 deficient murine cell extracts. 1250 28

Concurrent activation of poly (ADP-ribose) polymerase (PARP) and DNA ligase was observed in cultured human epidermal keratinocytes (HEK) exposed to the DNA alkylating compound sulfur mustard (SM), suggesting that DNA ligase activation could be due to its modification by PARP. Using HEK, intracellular 3H-labeled NAD+ (3H-adenine) was metabolically generated and then these cells were exposed to SM (1 mM). DNA ligase I isolated from these cells was not 3H-labeled, indicating that DNA ligase I is not a substrate for (ADP-ribosyl)ation by PARP. In HEK, when PARP was inhibited by 3-amino benzamide (3-AB, 2 mM), SM-activated DNA ligase had a half-life that was four-fold higher than that observed in the absence of 3-AB. These results suggest that DNA repair requires PARP, and that DNA ligase remains activated until DNA damage repair is complete. The results show that in SM-exposed HEK, DNA ligase I is activated by phosphorylation catalysed by DNA-dependent protein kinase (DNA-PK). Therefore, the role of PARP in DNA repair is other than that of DNA ligase I activation. By using the DNA ligase I phosphorylation assay and decreasing PARP chemically as well as by PARP anti-sense mRNA expression in the cells, it was confirmed that PARP does not modify DNA ligase I. In conclusion, it is proposed that PARP is essential for efficient DNA repair; however, PARP participates in DNA repair by altering the chromosomal structure to make the DNA damage site(s) accessible to the repair enzymes.
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PMID:Poly (ADP-ribose) polymerase (PARP) is essential for sulfur mustard-induced DNA damage repair, but has no role in DNA ligase activation. 1690 6

Engagement of integrin cell adhesion receptors suppresses bleomycin (BLM)-induced DNA strand breakage in endothelial cells. Previous investigation of cells from poly(ADP-ribose) polymerase (PARP)-1 knockout mice and with an inhibitor of the enzyme indicated that this facilitator of base excision repair (BER) is required for integrin-mediated suppression of DNA strand breakage. Here, small inhibitory RNA (siRNA) was used to assess the requirement for the BER proteins, DNA ligase III (Lig3) alpha, PARP-1, and X-ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1), and for the long-patch BER ligase, DNA ligase I (Lig1), in integrin-mediated protection from BLM-induced DNA breakage. Murine lung endothelial cells (MLECs) were transfected with siRNA, treated with anti-beta1 integrin antibody, and then BLM. 3'-OH in DNA and accumulation of phosphorylated histone H2AX (gammaH2AX), which reflects double-strand breakage, were measured. Integrin antibody inhibited the increases in 3'-OH caused by BLM in MLECs transfected with either control or Lig1 siRNA. However, after knockdown of Lig3alpha, PARP-1, or XRCC1, suppression of DNA breakage by integrin antibody was limited. BLM increased gammaH2AX levels, and integrin treatment inhibited this by 57 to 73% in MLECs transfected with control siRNA. Integrin engagement also inhibited increases in gammaH2AX in BLM-treated cells transfected with Lig1 siRNA. In contrast, Lig3alpha, PARP-1, and XRCC1 siRNAs prevented integrin-mediated inhibition of BLM-induced gammaH2AX levels. The results suggest that the BER proteins, Lig3alpha, PARP-1, and XRCC1, are required for integrin-mediated suppression of BLM-induced DNA breakage.
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PMID:Base excision repair proteins are required for integrin-mediated suppression of bleomycin-induced DNA breakage in murine lung endothelial cells. 1720 2

Human DNA ligase I (hLigI) joins Okazaki fragments during DNA replication and completes excision repair via interactions with proliferating cell nuclear antigen and replication factor C (RFC). Unlike proliferating cell nuclear antigen, the interaction with RFC is regulated by hLigI phosphorylation. To identity of the site(s) involved in this regulation, we analyzed phosphorylated hLigI purified from insect cells by mass spectrometry. These results suggested that serine 51 phosphorylation negatively regulates the interaction with RFC. Therefore, we constructed versions of hLigI in which serine 51 was replaced with either alanine (hLigI51A) to prevent phosphorylation or aspartic acid (hLigI51D) to mimic phosphorylation. hLigI51D but not hLigI51A was defective in binding to purified RFC and in associating with RFC in cell extracts. Although DNA synthesis and proliferation of hLigI-deficient cells expressing either hLig51A or hLig51 was reduced compared with cells expressing wild-type hLigI, cellular senescence was only observed in the cells expressing hLigI51D. Notably, these cells had increased levels of spontaneous DNA damage and phosphorylated CHK2. In addition, although expression of hLigI51A complemented the sensitivity of hLigI-deficient cells to a poly (ADP-ribose polymerase (PARP) inhibitor, expression of hLig151D did not, presumably because these cells are more dependent upon PARP-dependent repair pathways to repair the damage resulting from the abnormal DNA replication. Finally, neither expression of hLigI51D nor hLigI51A fully complemented the sensitivity of hLigI-deficient cells to DNA alkylation. Thus, phosphorylation of serine 51 on hLigI plays a critical role in regulating the interaction between hLigI and RFC, which is required for efficient DNA replication and repair.
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PMID:Phosphorylation of serine 51 regulates the interaction of human DNA ligase I with replication factor C and its participation in DNA replication and repair. 2295 33