ADP-ribosylation of nonhistone high mobility group proteins in intact cells

The ADP-ribosylation of nonhistone, high mobility group (HMG) proteins in intact cultured cells was investigated. Radioactively labeled adenosine was used as a precursor to detect (ADP-ribose)n on protein. A protein fraction enriched in HMG proteins and histone H1 was separated from RNA and DNA by CsCl density gradient centrifugation, 5% perchloric acid extraction, and CM-Sephadex C-50 column chromatography. Poly- and mono(ADP-ribose) were recovered following alkaline hydrolysis, and 5'-AMP and (2'-(5"-phosphoribosyl)-5'-AMP) were produced by phosphodiesterase treatment, indicating that the protein-bound radioactive material was (ADP-ribose)n. An average chain length of 1.5 to 1.8 was determined. Analysis of proteins by sodium dodecyl sulfate and acetic acid/urea polyacrylamide gel electrophoresis demonstrated that HMG 1, 2, 14, and 17 as well as histone H1 contained (ADP-ribose)n. Treatment of cells with 3-aminobenzamide, an inhibitor of (ADP-ribose)n synthetase, decreased endogenous ADP-ribosylation in both types of chromosomal proteins but that of HMG 14 and 17 was affected more.     

ADP-ribosylation of chromosomal proteins and mouse mammary tumor virus gene expression. Glucocorticoids rapidly decrease endogenous ADP-ribosylation of nonhistone high mobility group 14 and 17 proteins

The relationship between endogenous ADP-ribosylation of chromosomal proteins and glucocorticoid-regulated mouse mammary tumor virus gene expression was investigated in cultured mouse mammary tumor cells. It was observed that glucocorticoids quickly decreased endogenous (ADP-ribose)n on the nonhistone high mobility group (HMG) 14 and 17 proteins. The half-time for this loss was 8 and 17 min, respectively, for the two proteins. (ADP-ribose)n on HMG 1 and 2 and on histone H1 was less susceptible to hydrolysis during glucocorticoid treatment. The rapid loss of (ADP-ribose)n from HMG 14 and 17 occurred in the same time frame as the induction of mouse mammary tumor virus RNA synthesis by glucocorticoids in these cells (Young, H. A., Shih, T. Y., Scolnick, E. M., and Parks, W. P. (1977) J. Virol. 21, 139-149). 3-Amino-benzamide, a specific inhibitor of (ADP-ribose)n synthetase, increased mouse mammary tumor virus RNA levels with an accompanying decrease in endogenous ADP-ribosylation of HMG 14 and 17. These results show that a decrease in endogenous ADP-ribosylation of HMG 14 and 17 is a consequence of glucocorticoid action and suggest that loss of (ADP-ribose)n from these proteins may be an important event in mouse mammary tumor virus gene expression.     

Adenosine diphosphate ribosylation of chicken-erythrocyte histones H1, H5 and high-mobility-group proteins by purified calf-thymus poly(adenosinediphosphate-ribose) polymerase

Poly(ADP-ribosylation) of histones H1, H5 and non-histone chromosomal high-mobility-group proteins HMG 1, 2, 14 and 17 from chicken erythrocytes by purified calf thymus poly(ADP-ribose) polymerase was studied using acid/urea/Triton gel electrophoresis and autoradiography. With histone H1, besides ADP-ribosylated H1 supporting short chains of polymer, the appearance of H1 'dimer' was observed and this reaction was dependent on NAD concentration and incubation time. In addition, highly modified and/or aggregated species of histone H1 were observed. Histone H5 was slightly ADP-ribosylated at low NAD concentrations. At higher NAD concentrations or after longer incubations the formation of H5 'dimer' and of more modified forms of H5 could be observed. HMG 1 and HMG 2 were found to be ADP-ribosylated, the reaction being dependent on NAD concentration and time. Here again some discrete intermediates appeared. HMG 14 and HMG 17 were only slightly ADP-ribosylated under our experimental conditions. These results indicate that the purified DNA-independent poly(ADP-ribose) polymerase can catalyse the formation of H1 'dimer' as in nuclei and nucleosomes and that H5 and HMG proteins can also be ADP-ribosylated and produce well-defined higher complexes. These modifications of nuclear proteins may provide a means of localized conformational changes of the chromatin structure in vivo.     

Unique acceptors for poly(ADP-ribose) in resting,proliferating and DNA-damaged human lymphocytes

Acceptor proteins for poly(adenosine diphosphoribosyl)ation were determined in resting human lymphocytes, in lymphocytes with N-methyl-N′-nitro-N-nitrosoguanidine-induced DNA damage and in lymphocytes stimulated to proliferate by phytohemagglutinin. Kinetic studies showed that the increase in ADP-ribosylation which occurred in response to N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) treatment was greater in magnitude but more transient in duration than that which occurred in phytohemagglutinin-stimulated cells. Gel electrophoretic analyses revealed that MNNG treatment and phytohemagglutinin stimulation both caused an increase in ADP-ribosylation of poly(ADP-ribose) polymerase and core histones. In MNNG-treated cells, an increase in ADP-ribosylation of histone H1 was also observed. In contrast, phytohemagglutinin-stimulated cells showed no increase in ADP-ribosylation of histone H1. In MNNG-treated cells there was also ADP-ribosylation of a protein of molecular weight 62 000, while in phytohemagglutinin-stimulated cells there was a marked increase in ADP-ribosylation of a protein of molecular weight 96000. MNNG treatment of phytohemagglutinin-stimulated cells produced a pattern of ADP-ribosylation that appeared to be due to the combined effects of the individual treatments. 3-Aminobenzamide effectively inhibited ADP-ribosylation under all treatment conditions.     

Acceptor proteins for (ADP-ribose)n in the HeLa S3 cell cycle

The acceptor proteins for (ADP-ribose)n were investigated by using nuclei or chromosomes isolated from specific phases of the cell cycle of HeLa S3 cells. Analysis of HMG proteins and histone H1 by acetic acid/urea polyacrylamide gel electrophoresis demonstrated that the (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 increased by 12- and 5-fold, respectively, in the metaphase chromosomes as compared with that in the G1 phase cell nuclei. The degree of (ADP-ribosyl)n-ation of these proteins in the S phase cell nuclei was as low as that in G1 phase cell nuclei. In the G2 phase cell nuclei, the degrees of (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 were about 5- and 2-fold greater, respectively, as compared with that in the G1 phase cell nuclei. The (ADP-ribosyl)n-ation of HMG 1 and 2 was constant through the cell cycle except for a slight decrease in the S phase. The data may imply that the (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 is linked to chromatin structural changes in mitosis.     

ADP-ribosylation of diadenosine 5',5"-P1,P4-tetraphosphate by poly(ADP-ribose) polymerase in vitro

When the effect of diadenosine 5',5"'-P1,P4-tetraphosphate on a purified poly(ADP-ribose) polymerase reaction was examined, the compound strongly inhibited ADP-ribosylation reaction of histone, while the compound was much less inhibitory of the Mg2+-dependent automodification of this enzyme. In an attempt to study the mechanism of the inhibition, we analyzed the total reaction products, which were synthesized from NAD+ in the presence of diadenosine 5',5"'-P1,P4-tetraphosphate in a reaction mixture for ADP-ribosylation of histone, and found that a new, low molecular product was predominantly synthesized instead of ADP-ribosylated histone in the reaction. Approximately 90% of added NAD+ was converted into this low molecular product under an appropriate reaction condition. Further analysis revealed that the product was mono- and oligo(ADP-ribosyl)ated diadenosine nucleotide and that the bound oligo(ADP-ribose) is elongating at one end of the product during the reaction. Thus, the present study clearly demonstrated that diadenosine 5',5"'-P1,P4-tetraphosphate functions as an acceptor for ADP-ribose in a poly(ADP-ribose) polymerase reaction in vitro. The finding that histone H1 is required in the reaction mixture for the synthesis of this new product suggests that histone H1 and the diadenosine compound interact during this modification reaction.     

Reaction of poly(ADP)-ribosylation of histone H1 in the presence of P1,P4-bis(5'-adenosyl)tetraphosphate and its phosphonate analogs

Effects of P1,P4-bis(5'-adenosyl)tetraphosphate and its phosphonate analogs on the ADP-ribosylation of H1 catalyzed by bovine testis ADP-ribose polymerase was investigated. Analogs App[CH(COCH3)]ppA and Ap[CH2]pppA as well as Ap4A inhibited poly(ADP)-ribosylation of histone H1 and at the same time accepted the ADP-ribosyl moiety of NAD. It was shown that inhibition of ADP-ribosylation of histone H1 is due to the competition of nucleotides with histone H1 for accepting ADP-ribosyl moiety of NAD on the one hand, and alteration of acceptor properties of the histone H1 on the other.     

Non-histone chromosomal protein HMG1 modulates the histone H1-induced condensation of DNA

Circular dichroic spectra revealed that the previously known regular, asymmetric condensation of DNA by H1 histone was modulated by HMG1, a nonhistone chromosomal protein. Under approximately physiological salt and pH conditions (150 mM NaCl, pH 7), ellipticities at 270 nm were observed as follows: DNA, 9 X 10(3) degree, cm2/dmol nucleotide; DNA X H1 histone complex (1:0.4, w/w), -37 X 10(3) degree, cm2/dmol nucleotide, and DNA X H1 X HMG1 complex (1:0.4:0.4 w/w/w), -52 X 10(3) degree, cm2/dmol. HMG1 by itself did not distort the spectrum of DNA, showing that the effect of HMG1 on the DNA X H1 complex was not simply the summation of individual effects of HMG1 and H1 on the DNA spectrum. The effect of added HMG1 on the spectrum of the preformed DNA X H1 complex depended on the amount of HMG1 added and developed slowly (a day) as if a structure required annealing. The ternary complex, DNA X HMG1 X 1, seemed to represent a specific structure, since its formation depeNded on the reduced sulfhydryl state of HMG1; the disulfide form of HMG1, which was shown by circular dichroism to contain more random coil than did the reduced form, had no effect on the circular dichroic spectrum of the DNA X H1 complex.     

MNNG-induced cell death is controlled by interactions between PARP-1, poly(ADP-ribose) glycohydrolase, and XRCC1

PARP-1 (poly(ADP-ribose) polymerases) modifies proteins with poly(ADP-ribose), which is an important signal for genomic stability. ADP-ribose polymers also mediate cell death and are degraded by poly(ADP-ribose) glycohydrolase (PARG). Here we show that the catalytic domain of PARG interacts with the automodification domain of PARP-1. Furthermore, PARG can directly down-regulate PARP-1 activity. PARG also interacts with XRCC1, a DNA repair factor that is recruited by DNA damage-activated PARP-1. We investigated the role of XRCC1 in cell death after treatment with supralethal doses of the alkylating agent MNNG. Only in XRCC1-proficient cells MNNG induced a considerable accumulation of poly(ADP-ribose). Similarly, extracts of XRCC1-deficient cells produced large ADP-ribose polymers if supplemented with XRCC1. Consequently, MNNG triggered in XRCC1-proficient cells the translocation of the apoptosis inducing factor from mitochondria to the nucleus followed by caspase-independent cell death. In XRCC1-deficient cells, the same MNNG treatment caused non-apoptotic cell death without accumulation of poly(ADP-ribose). Thus, XRCC1 seems to be involved in regulating a poly(ADP-ribose)-mediated apoptotic cell death.     

Production of anti-(ADP-ribose) antibodies with the aid of a dinucleotide-pyrophosphatase-resistant hapten and their application for the detection of mono(ADP-ribosyl)ated polypeptides

Previous attempts to produce anti-(ADP-ribose) antibodies by immunization of rabbits with ADP-ribose conjugated to serum albumin had resulted in the production of 5'AMP-specific antibodies [Bredehorst et al. (1978) Eur. J. Biochem. 82, 105-113]. To obtain true anti-(ADP-ribose) antibodies an antigen was constructed that was resistant to enzymic degradation at the pyrophosphate group. The enzymically active beta-methylene derivative of NAD (NAD[CH2]) was synthesized from ADP containing a methylene bridge (CH2) instead of an oxygen in the diphosphate group. NAD[CH2] was converted to its N6-[(2-carboxyethyl)thiomethyl] derivative and hydrolyzed to the corresponding ADP[CH2]-ribose derivative which was then coupled to bovine serum albumin. The antibodies obtained with this antigen were specific for free or protein-bound ADP-ribose groups, except for a cross-reaction with FAD, AMP, ADP, ATP or poly(ADP-ribose) interfered with [3H]ADP-ribose tracer binding only at higher concentrations. No interference was observed with poly(A), RNA and DNA at 6000-fold excess. The antibodies were purified on a novel type of affinity matrix. This was formed from NAD and guanidinobutyrate by a cholera-toxin-catalyzed reaction and the product, ADP-ribosyl guanidinobutyrate, was bound to Affi Gel by carbodiimide-aided condensation. The purified antibodies allowed the detection of ADP-ribose conjugated to polypeptides in amounts lower than 1 pmol as demonstrated by immunoblotting of [14C]ADP-ribosylated elongation factor 2. They also could be used to observe in situ, by indirect immunofluorescence, the increased mono(ADP-ribosyl)ation of nuclear proteins in dimethyl-sulfate-treated cells, and to show that histone H2B was the principal histone acceptor of single ADP-ribose groups in alkylated 3T3 cells.     

The effect of inhibitors of ADP ribosylation on the restoration of the mitotic cycle and on DNA repair after the action of ionizing radiation in Chinese hamster cells

Specific inhibitors of poly(ADP-ribose)polymerase-3-aminobenzamide and 3-metoxybenzamide (6, 12 mM) have been shown to: 1) reduce survival of X-irradiated CHO K1 cells to a slight degree; 2) increase S- and particularly G2-delays in X-irradiated cells, while progressing through the cell cycle as analysed by the DNA flow cytofluorimetry; 3) reduce effectiveness of DNA single-strand breaks repair. The above data suggest a definite role of ADP ribosylation in the cell repair activity.     

A simple and rapid method for the detection of poly(ADP-ribose) by flow cytometry

Measurement of poly(ADP-ribose) levels was performed by a new method using a monoclonal antibody against poly(ADP-ribose) and flow cytometry from small amount of cultured cells without the need for isolation of poly(ADP-ribose) polymer. The increase of poly(ADP-ribose)-associated fluorescence intensity was observed in individual human leukemic HL-60 cells when treated with the carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and was blocked by the treatment with 3-aminobenzamide before MNNG treatment. It is easy and rapid to detect the time-dependent change of poly(ADP-ribose) levels in HL-60 cells after MNNG treatment. We easily found that the increase of the poly(ADP-ribose) level in nicotinic acid-treated lymphocytes after MNNG treatment was observed, but not in nicotinamide-treated lymphocytes. We investigated the change of poly(ADP-ribose) levels especially in the early phase of apoptosis. Our method is simple and rapid. It is suggested that the investigation of poly(ADP-ribosyl)ation in various fields is possible by using this new method.     

Does high-mobility-group non-histone protein HMG 1 interact specifically with histone H1 subfractions?

The interaction of the non-histone chromosomal protein HMG (high-mobility group) 1 with histone H1 subfractions was investigated by equilibrium sedimentation and n.m.r. sectroscopy. In contrast with a previous report [Smerdon & Isenberg (1976) Biochemistry 15, 4242--4247], it was found, by using equilibrium-sedimentation analysis, that protein HMG 1 binds to all three histone H1 subfractions CTL1, CTL2, and CTL3, arguing against there being a specific interaction between protein HMG 1 and only two of the subfractions, CTL1 and CTL2. Raising the ionic strength of the solutions prevents binding of protein HMG 1 to total histone H1 and the three subfractions, suggesting that the binding in vitro is simply a non-specific ionic interaction between acidic regions of the non-histone protein and the basic regions of the histone. Protein HMG 1 binds to histone H5 also, supporting this view. The above conclusions are supported by n.m.r. studies of protein HMG 1/histone H1 subfraction mixtures. When the two proteins were mixed, there was little perturbation of the n.m.r. spectra and there was no evidence for specific interaction of protein HMG 1 with any of the subfractions. It therefore remains an open question as to whether protein HMG 1 and histone H1 are complexed together in chromatin.     

Non-histone chromosomal protein HMG1 reduces the histone H5-induced changes in c.d. spectra of DNA: the acidic C-terminus of HMG1 is necessary for binding to H5

Chemical cross-linking was used to study the interaction between non-histone high-mobility-group (HMG)1 and histone H5 in free solution. The presence of acidic C-terminal domain in HMG1 was shown to be a prerequisite for HMG1 binding to histone H5. The objective of this communication is to ascertain whether HMG1 could affect the conformation of DNA associated with a linker histone H5. Complexes of histone H5 with chicken erythrocyte DNA or an alternating purine-pyrimidine polynucleotide poly[d(A-T)] were prepared at different molar ratios H5/DNA. Changes in DNA conformation in the complexes with histone H5 or H5/HMG1 were monitored by circular dichroism (c.d.). Depending on the molar ratio H5/poly[d(A-T)], under conditions limiting the complex aggregation, three distinct types of c.d. spectra were observed. The addition of HMG1 to H5-DNA complexes reduced in all cases the histone H5-induced conformational changes in poly[d(A-T)]. The sensitivity of H5-poly[d(A-T)] complexes to HMG1 was inversely proportional to the amount of H5 in the complex. The effect of HMG1 was not observed upon removal of the acidic C-terminal domain of HMG1.     

Phenylmethylsulfonyl fluoride stimulates proteolysis of nuclear proteins from chick liver.

The degradation of H1 histone and high mobility group (HMG) nonhistone proteins was stimulated when the homogenate from chick liver was incubated in the presence of phenylmethylsulfonyl fluoride (PMSF). Two proteinase inhibitors, elastatinal and chymostatin, significantly inhibited the PMSF-stimulated degradation of H1 histone and HMG proteins. On the contrary, other proteinase inhibitors like leupeptin, pepstatin, trypsin inhibitor, antipain, o-phenanthroline and EDTA had no effect on the degradation of the nuclear proteins. These results warn the researcher to be cautious while using PMSF for preparation of nuclear proteins such as H1 histone and HMG proteins.     

Alkylation-induced mono(ADP-ribosyl)-histones H1 and H2B. Hydroxylamine-resistant linkage in hepatoma cells

Treatment of hepatoma AH 7974 cells with dimethyl sulfate led to a marked accumulation in vivo of mono)ADP-ribosyl)-histone H1A, H1B, H1 and H2B, respectively. In these conjugates, most of the modifying groups were linked to the acceptor proteins by an 'unusual' bond not described so far for ADP-ribosyl histone conjugates. It resisted treatment with 3M hydroxylamine, 0.1M picrylsulfonate and mild alkali, which excluded a linkage through carboxyl or guanidino residues. The stability of these conjugates formed endogenously differed also from 'non-enzymic' histone H1 conjugates formed by incubation of free ADP-ribose with the histone. Histone-linked mono(ADP-ribosyl) residues synthesized in hepatoma cells in response to alkylation were located exclusively in the domains that interact with DNA, i.e. in the non-globular C-terminal tail of histone H1 and in the N-terminus of histone H2B. Besides poly(ADP-ribosyl)ation, the modification of histones by single ADP-ribose groups may represent an independent process to modulate DNA/histone interaction.     

ADP-ribosylation of nuclear proteins in vivo. Identification of histone H2B as a major acceptor for mono- and poly(ADP-ribose) in dimethyl sulfate-treated hepatoma AH 7974 cells

Nuclear mono- and poly(ADP-ribosyl) protein conjugates formed in living hepatoma AH 7974 cells in response to treatment with the alkylating agent dimethyl sulfate have been studied. They were isolated from the perchloric acid precipitate of freshly prepared nuclei in a relatively pure form and with an overall yield of more than 80%, utilizing aminophenylboronic acid-agarose chromatography. Exposure of the cells to 400 microM dimethyl sulfate led to a transient rise of ADP-ribosylated proteins. After 20 min, the level of endogenous poly(ADP-ribosyl) residues increased by a factor of 21, amounting to a final value of 772 +/- 57 pmol/mg of DNA while the mono(ADP-ribosyl) residues were raised to even higher concentrations (1864 pmol/mg of DNA), corresponding to a 12-fold stimulation as compared to untreated cells. As a result of dimethyl sulfate treatment, the amount of acceptor protein being modified by (ADP-ribose)n was elevated 15-fold, reaching a final proportion of 2.3 +/- 0.4% of total nuclear protein. The increase in (ADP-ribosyl)n-modified proteins was suppressed by benzamide, a potent inhibitor of poly(ADP-ribose) synthetase. More than half of the nuclear mono- and poly(ADP-ribosyl) residues were linked to histone H2B. The modifying residues could be removed from the major acceptor by treatment with 0.1 M NaOH, but not with neutral hydroxylamine. Minor amounts of other histones, especially of histone H4, were possibly also ADP-ribosylated under the stimulating effect of dimethyl sulfate. In addition, several nonhistone proteins with apparent molecular masses of 100-116 and 170 kDa were found to carry substantial amounts of mono- and poly(ADP-ribose).     

Poly(ADP-ribose) turnover in quail myoblast cells: Relation between the polymer level and its catabolism by glycohydrolase

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 \sgmaelig;M for 30 min induced a marginal decrease of 15% in the NAD content. For C3H10T1/2 cell line, 64 \sgmaelig;M 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.