Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P16104 (H2AX)
 3,930 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We used a proteomic approach to identify phosphopeptide-binding modules mediating signal transduction events in the DNA damage response pathway. Using a library of partially degenerate phosphopeptides, we identified tandem BRCT (BRCA1 carboxyl-terminal) domains in PTIP (Pax transactivation domain-interacting protein) and in BRCA1 as phosphoserine- or phosphothreonine-specific binding modules that recognize substrates phosphorylated by the kinases ATM (ataxia telangiectasia-mutated) and ATR (ataxia telangiectasia- and RAD3-related) in response to gamma-irradiation. PTIP tandem BRCT domains are responsible for phosphorylation-dependent protein localization into 53BP1- and phospho-H2AX (gamma-H2AX)-containing nuclear foci, a marker of DNA damage. These findings provide a molecular basis for BRCT domain function in the DNA damage response and may help to explain why the BRCA1 BRCT domain mutation Met1775 --> Arg, which fails to bind phosphopeptides, predisposes women to breast and ovarian cancer.
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PMID:BRCT repeats as phosphopeptide-binding modules involved in protein targeting. 1457 10

The Bloom syndrome gene, BLM, encodes a RecQ DNA helicase that when absent from the cell results in genomic instability and cancer predisposition. We show here that BLM is a substrate for small ubiquitin-like modifier (SUMO) modification, with lysines at K317, K331, K334 and K347 being preferred sites of modification. Unlike normal BLM, a double mutant BLM protein with lysine to arginine substitutions at residues 317 and 331 was not modified by SUMO, and it failed to localize efficiently to the PML nuclear bodies. Rather, double mutant BLM protein induced the formation of DNA damage-induced foci (DDI) that contained BRCA1 protein and phosphorylated histone H2AX. Double mutant BLM only partially complemented the genomic instability phenotypes of Bloom syndrome cells as assessed by sister-chromatid exchange and micronuclei formation assays. These results constitute evidence that BLM is a DNA damage sensor that signals the formation of DDI, and they establish SUMO modification as a negative regulator of BLM's signaling function.
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PMID:Intra-nuclear trafficking of the BLM helicase to DNA damage-induced foci is regulated by SUMO modification. 1582 7

The cellular response to DNA damage includes the orderly recruitment of many protein complexes to DNA lesions. The MRE11-RAD50-NBS1 (MRN) complex is well known to localize early to sites of DNA damage, but the post-translational modifications required to mobilize it to DNA damage sites are poorly understood. Recently, we have shown that MRE11 is arginine methylated in a C-terminal glycine-arginine rich (GAR) domain by protein arginine methyltransferase 1 (PRMT1). Arginine methylation is required for the exonuclease activity of MRE11 and the intra-S phase DNA damage response. Herein, we report that cells treated with methylase inhibitors failed to relocalize MRE11 from PML nuclear bodies to sites of DNA damage and formed few gamma-H2AX foci. We also demonstrate that PRMT1 is a component of PML nuclear bodies where it colocalizes with MRE11.Using cellular fractionation, we demonstrate that methylated MRE11 is predominantly associated with nuclear structures and that MRE11 methylated arginines were required for this association. These results suggest that MRE11 methylation regulates its association with nuclear structures such as PML nuclear bodies and sites of DNA damage.
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PMID:Methylation of MRE11 regulates its nuclear compartmentalization. 1597 Jun 67

MDC1 (mediator of DNA damage checkpoint protein 1) regulates the recognition and repair of DNA double strand breaks in mammalian cells through its interactions with nuclear foci containing the COOH-terminally phosphorylated form of the histone variant, H2AX. Here we demonstrate that the tandem BRCT repeats of MDC1 directly bind to the phosphorylated tail of H2AX-Ser(P)-Gln-Glu-Tyr, in a manner that is critically dependent on the free carboxylate group of the COOH-terminal Tyr residue. We have determined the x-ray crystal structure of the MDC1 BRCT repeats at 1.45 Angstroms resolution. By a comparison with the structure of the BRCA1 BRCT bound to a phosphopeptide, we suggest that two arginine residues in MDC1, Arg(1932) and Arg(1933) may recognize the COOH terminus of the peptide as well as the penultimate Glu of H2AX, while Gln(2013) may provide additional specificity for the COOH-terminal Tyr.
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PMID:Structure of the BRCT repeat domain of MDC1 and its specificity for the free COOH-terminal end of the gamma-H2AX histone tail. 1604 3

The p53-binding protein 1 (53BP1) is rapidly recruited to sites of DNA double-strand breaks and forms characteristics nuclear foci, demonstrating its role in the early events of detection, signaling and repair of damaged DNA. 53BP1 contains a glycine arginine rich (GAR) motif of unknown function within its kinetochore-binding domain. Herein, we show that the GAR motif of 53BP1 is arginine methylated by protein arginine methyltransferase 1 (PRMT1), the same methyltransferase that methylates MRE11. 53BP1 contains asymmetric dimethylarginines (aDMA) within cells, as detected with methylarginine-specific antibodies. Amino acid substitution of the arginines within the GAR motif of 53BP1 abrogated binding to single and double-stranded DNA, demonstrating that the GAR motif is required for DNA binding activity of 53BP1. Fibroblast cells treated with methylase inhibitors failed to relocalize 53BP1 to sites of DNA damage and formed few gamma-H2AX foci, consistent with our previous data that MRE11 fails to relocalize to DNA damage sites in cells treated with methylase inhibitors. Our findings identify the GAR motif as a region required for 53BP1 DNA binding activity and as the site of methylation by PRMT1.
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PMID:The GAR motif of 53BP1 is arginine methylated by PRMT1 and is necessary for 53BP1 DNA binding activity. 1629 45

The initiation and propagation of the early processes of bystander signaling induced by low-dose alpha-particle irradiation are very important for understanding the underlying mechanism of the bystander process. Our previous investigation showed that the medium collected from cell culture exposed to low-dose alpha-particle rapidly induced phosphorylated form of H2AX protein foci formation among the non-irradiated medium receptor cells in a time-dependent manner. Using N(G)-methyl-L-arginine, 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate and N(omega)-nitro-L-arginine (L-NNA) treatment before exposure to 1 cGy alpha-particle, we showed in the present study that nitric oxide (NO(*)) produced in the irradiated cells was important and necessary for the DNA double strand break inducing activity (DIA) of conditioned medium and the generation of NO(*) in irradiated confluent AG1522 cells is in a time-dependent manner and that almost all NO(*) was generated within 15 min post-irradiation. Concurrently, the kinetics of NO(*) production in the medium of irradiated cells after irradiation was rapid and in a time-dependent manner as well, with a maximum yield observed at 10 min after irradiation with electron spin resonance analysis. Furthermore, our results that 7-Nitroindazole and L-NNA, but not aminoguanidine hemisulfate, treatment before exposure to 1 cGy alpha-particle significantly decrease the DIA of the conditioned medium suggested that constitutive NO(*) from the irradiated cells possibly acted as an intercellular signaling molecule to initiate and activate the early process (<or=30 min) of bystander response after low-dose irradiation.
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PMID:Constitutive nitric oxide acting as a possible intercellular signaling molecule in the initiation of radiation-induced DNA double strand breaks in non-irradiated bystander cells. 1701 33

Previous studies have shown that high NaCl can be genotoxic, either alone or combined with irradiation. However, little is known about the relationship between environmental NaCl at elevated conditions and radiation-induced bystander effects (RIBE). RIBE, which has been considered as non-targeted bystander responses, has been demonstrated to occur widely in various cell lines. In the present study, RIBE under the elevated NaCl culture condition was assessed in AG 1522 cells by both the induction of gamma-H2AX, a reliable marker of DNA double-strand break (DSB) for the early process (<1h post irradiation), and the generation of micronuclei (MN), a sensitive marker for relative long process of RIBE. Our results showed that in the absence of irradiation, NaCl at elevated concentration such as 8.0, 9.0 and 10.0g/L did not significantly increase the frequency of gamma-H2AX foci-positive cells and the number of foci per positive cell comparing with that NaCl at a normal concentration (6.8g/L). However, with 0.2cGy alpha-particle irradiation, the induced fraction of gamma-H2AX foci-positive cells and the number of induced gamma-H2AX foci per positive cell were significantly increased in both irradiated and adjacent non-irradiated regions. Similarly, the induction of MN by 0.2cGy alpha-particle irradiation also increased with the elevated NaCl concentrations. With N(G)-methyl-l-arginine, an inhibitor of nitric oxide synthase, the induced fraction of foci-positive cells was effectively inhibited both in 0.2cGy alpha-particle irradiated and adjacent non-irradiated regions under either normal or elevated NaCl conditions. These results suggested that the cultures with elevated NaCl medium magnified the damage effects induced by the low dose alpha-particle irradiation and nitric oxide generated by irradiation was also very important in this process.
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PMID:Elevated sodium chloride concentrations enhance the bystander effects induced by low dose alpha-particle irradiation. 1756 Jun 16

Human MRE11 is a key enzyme in DNA double-strand break repair and genome stability. Human MRE11 bears a glycine-arginine-rich (GAR) motif that is conserved among multicellular eukaryotic species. We investigated how this motif influences MRE11 function. Human MRE11 alone or a complex of MRE11, RAD50, and NBS1 (MRN) was methylated in insect cells, suggesting that this modification is conserved during evolution. We demonstrate that PRMT1 interacts with MRE11 but not with the MRN complex, suggesting that MRE11 arginine methylation occurs prior to the binding of NBS1 and RAD50. Moreover, the first six methylated arginines are essential for the regulation of MRE11 DNA binding and nuclease activity. The inhibition of arginine methylation leads to a reduction in MRE11 and RAD51 focus formation on a unique double-strand break in vivo. Furthermore, the MRE11-methylated GAR domain is sufficient for its targeting to DNA damage foci and colocalization with gamma-H2AX. These studies highlight an important role for the GAR domain in regulating MRE11 function at the biochemical and cellular levels during DNA double-strand break repair.
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PMID:A glycine-arginine domain in control of the human MRE11 DNA repair protein. 1828 53

Nuclear DNA helicase II (NDH II) was first isolated from calf thymus using a DNA-unwinding assay. Subsequently it has been shown to be a homologue of human RNA helicase A (RHA) and the maleless protein (MLE) from Drosophila. Accordingly, the protein possesses both DNA and RNA unwinding activities. Also, it can use all four NTPs or dNTPs to fuel the reaction. At its N-terminus it possesses two double-strand RNA binding domains (dsRBD I and II), while the C-terminus comprises an imperfect glycine (G)- and arginine (R)-rich repeat, a so-called RGG-box that preferably binds to ssDNA or ssRNA. Many proteins interact with NDH II both at its N- and C-terminus and thereby mediate transcriptional regulation, RNA processing, and transport, the DNA damage response and genome surveillance. The latter includes the histone variant gamma-H2AX and the Werner syndrome helicase (WRN). Here we describe experimental approaches to obtain mechanistic information about this important nuclear helicase.
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PMID:Molecular characterization of nuclear DNA helicase II (RNA helicase A). 2022 58

The fact that eukaryotic DNA is packed into chromatin constitutes a physical barrier to enzymes and regulatory factors to reach the DNA molecule for replication, transcription, recombination and repair. Although most studies in this field have concentrated on how chromatin regulates transcription, there is a recent emphasis on studying the role of chromatin in the response to DNA damage. Two main chromatin-remodeling mechanisms have been identified, namely, ATP-dependent chromatin-remodeling complexes and histone post-translational modifications (PTMs). PTMs constitute reversible covalent modifications in aminoacidic residues, such as serine and threonine phosphorylation, lysine acetylation, lysine and arginine methylation and lysine ubiquitylation, among others. Moreover, nucleosome composition can be modified by the incorporation of histone variants, which are assembled into nucleosomes independently of DNA replication. The phosphorylation of the histone variant H2AX (gammaH2AX) is one of the best examples of histone PTMs in response to DNA damage induction, but many others have recently been revealed. In this review, we focus on and summarize the best-known histone PTMs observed in excision repair (base excision and nucleotide excision) and double-strand break (non-homologous end-joining and homologous recombination) repair pathways. In brief, the interplay between chromatin remodelers and DNA repair factors is discussed in relation to DNA damage response mechanisms.
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PMID:Histone post-translational modifications in DNA damage response. 2040 19


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