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Virology Journal Mar 2008It has been demonstrated that the p53 pathway plays an important role in HIV-1 infection. Previous work from our lab has established a model demonstrating how p53 could...
It has been demonstrated that the p53 pathway plays an important role in HIV-1 infection. Previous work from our lab has established a model demonstrating how p53 could become inactivated in HIV-1 infected cells through binding to Tat. Subsequently, p53 was inactivated and lost its ability to transactivate its downstream target gene p21/waf1. P21/waf1 is a well-known cdk inhibitor (CKI) that can lead to cell cycle arrest upon DNA damage. Most recently, the p21/waf1 function was further investigated as a molecular barrier for HIV-1 infection of stem cells. Therefore, we reason that the restoration of the p53 and p21/waf1 pathways could be a possible theraputical arsenal for combating HIV-1 infection. In this current study, we show that a small chemical molecule, 9-aminoacridine (9AA) at low concentrations, could efficiently reactivate p53 pathway and thereby restoring the p21/waf1 function. Further, we show that the 9AA could significantly inhibit virus replication in activated PBMCs, likely through a mechanism of inhibiting the viral replication machinery. A mechanism study reveals that the phosphorylated p53ser15 may be dissociated from binding to HIV-1 Tat protein, thereby activating the p21/waf1 gene. Finally, we also show that the 9AA-activated p21/waf1 is recruited to HIV-1 preintegration complex, through a mechanism yet to be elucidated.
Topics: Aminacrine; Antiviral Agents; Cell Line; Cell Survival; Cyclin-Dependent Kinase Inhibitor p21; HIV-1; Humans; Leukocytes, Mononuclear; Phosphorylation; Reverse Transcription; Signal Transduction; T-Lymphocytes; Tumor Suppressor Protein p53; tat Gene Products, Human Immunodeficiency Virus
PubMed: 18348731
DOI: 10.1186/1743-422X-5-41 -
Proceedings of the National Academy of... Nov 1974Population changes induced by acridine mustards in haploid and diploid cultured cell lines from Rana pipiens were compared to test the expectation that recessive...
Population changes induced by acridine mustards in haploid and diploid cultured cell lines from Rana pipiens were compared to test the expectation that recessive mutations will be expressed in diploid cells with a frequency equal to the square of that in haploid cells, and to investigate the usefulness of such comparison for the screening of possible mutagens. The differences in survival frequency after treatment were much smaller than predicted on the basis of the expression of lethal (recessive) mutations alone. Survival was also affected by culture conditions, drug-resistance phenomena, and other cell properties. It is suggested that with the evolution of epigenetic processes for the production of stable phenotypes, the vertebrate cell also acquired more efficient means to prevent the expression of gene mutation and that the acridine compounds may affect both epigenetic and genetic changes.
Topics: Acridines; Aminacrine; Animals; Aza Compounds; Cell Line; Cell Survival; Clone Cells; Diploidy; Haploidy; Mustard Compounds; Mutagens; Nitrogen Mustard Compounds; Propylamines; Rana pipiens
PubMed: 4548187
DOI: 10.1073/pnas.71.11.4416 -
British Journal of Cancer Feb 1988Colonic tumour cells possess a cell surface protease capable of binding 9-aminoacridine to its active centre, thus locating cells when viewed under a fluorescence...
Colonic tumour cells possess a cell surface protease capable of binding 9-aminoacridine to its active centre, thus locating cells when viewed under a fluorescence microscope. In vivo and in frozen sections, the enzyme is masked by a protein inhibitor. This inhibitor can be displaced by formaldehyde fixation of the tissue and then replaced by adding a fresh extract of colon or lung tissue. The inhibitor is modified by oxidation; provided by air, oxidized glutathione or potassium permanganate, resulting in a change in conformation in the inhibitor and this then results in the enzyme binding the fluorescent probe. The effect of oxidation can be reversed by dithiothreitol. It is proposed that these changes are brought about by a disulphide exchange acting on the inhibitor which indirectly controls the activity of the cell surface enzyme in vivo. The steps described above can be conveniently followed on sections of tissue mounted on a microscope slide; this has the advantage that the same cells can be monitored during a sequence of reactions. It is believed that these techniques could well be applied to other enzyme systems than the tumour protease described in this study.
Topics: Aminacrine; Carboxylic Ester Hydrolases; Colonic Neoplasms; Endopeptidases; Enzyme Reactivators; Formaldehyde; Glutathione; Glutathione Disulfide; Humans; Microscopy, Fluorescence; Oxygen; Potassium Permanganate; Staining and Labeling
PubMed: 2451931
DOI: 10.1038/bjc.1988.33 -
Journal of Virology Feb 1980A maturable head-related particle of bacteriophage T4 has been identified and characterized. This epsilon-particle has the same size as the prehead, but its shell is...
A maturable head-related particle of bacteriophage T4 has been identified and characterized. This epsilon-particle has the same size as the prehead, but its shell is made of the cleaved product of gene 23 (gp23*). It contains internal matter, most likely the processed core proteins, which is lost or modified by experimental manipulations. It accumulates, together with partially filled ("grizzled") heads, in T4 infected cells that are treated with 9-aminoacridine. On sections of "well-preserved" cells the epsilon-particles are not identifiable with certainty; a more or less empty breakdown product of them becomes visible when cytoplasmic leakage is induced. The number of particles per cell is then in agreement with the biochemically and with the number of particles counted in lysates. Morphologically and biochemically, the isolated epsilon-particles closely resemble the empty small particles of 17- -infected cells described in previous papers of this series. Both are composed of gp23* and are still unexpanded, so that they are not yet able to bind the minor head proteins soc and hoc. We discuss the possibility of the epsilon-particle being an intermediate on the normal T4 wild-type head maturation pathway.
Topics: Aminacrine; Aminoacridines; Capsid; Escherichia coli; Microscopy, Electron; Models, Biological; Morphogenesis; T-Phages; Viral Proteins
PubMed: 6997509
DOI: 10.1128/JVI.33.2.830-844.1980 -
Biophysical Journal Jun 1989The fluorescence of 9-aminoacridine (9-AA) is quenched in vesicular suspensions containing negatively charged lipid headgroups (e.g., phosphatidylserine) upon imposition...
The fluorescence of 9-aminoacridine (9-AA) is quenched in vesicular suspensions containing negatively charged lipid headgroups (e.g., phosphatidylserine) upon imposition of a transmembrane (inside acidic) pH-gradient. It is shown that this fluorescence loss is accompanied by the formation of 9-AA dimers that undergo a transition in the dimer excited state to a dimer-excimer state. This result has been obtained on the basis of the specific dimer fluorescence excitation and hypochromic absorbance spectra that are redshifted by maximally 275 cm-1 (4.4 nm) with respect to the corresponding monomer spectra, as well as by the detection of the characteristic broad excimer emission band, centered at 560 nm. The existence of the spectrally distinct dimer-excimer is further corroborated by fluorescence life-time measurements that indicate an increased lifetime of up to 24 ns for this complex as compared with the normal monomer fluorescence lifetime of 16 ns. The formation of this dimer-excimer complex from the monomers can be reversed completely and the original monomeric spectral properties restored after the abolishment of the electrochemical proton gradient. In addition to the delta pH-induced dimer redshift in absorbance and fluorescence excitation, a further small redshift in monomer absorbance, fluorescence excitation, and emission spectra is observed due solely to the presence of the negatively charged phospholipid headgroups.
Topics: Aminacrine; Aminoacridines; Hydrogen-Ion Concentration; Kinetics; Liposomes; Models, Biological; Phosphatidylserines; Spectrometry, Fluorescence
PubMed: 2765648
DOI: 10.1016/S0006-3495(89)82907-8 -
Bioscience, Biotechnology, and... Jul 1997Some derivatives of 9-aminoacridine (1) were synthesized, and their frameshift mutagenicity and DNA binding affinity were studied. The introduction of a methyl group...
Some derivatives of 9-aminoacridine (1) were synthesized, and their frameshift mutagenicity and DNA binding affinity were studied. The introduction of a methyl group into the acridine ring of 1 reduced the mutagenic activity and the intercalative DNA binding affinity, while the introduction of chlorine increased them. Halogenated derivatives of 1 showed higher toxicity against Salmonella typhimurium TA1537.
Topics: Aminacrine; Animals; DNA; Frameshift Mutation; Halogens; Liver; Methylation; Mutagenicity Tests; Mutagens; Rats; Salmonella typhimurium; Spectrum Analysis; Structure-Activity Relationship
PubMed: 9255975
DOI: 10.1271/bbb.61.1121 -
The Journal of Biological Chemistry Jul 1984Mitochondrial nicotinamide nucleotide transhydrogenase from beef heart was purified by a novel procedure involving fast protein liquid chromatography and characterized...
Energy-linked nicotinamide nucleotide transhydrogenase. Properties of proton-translocating mitochondrial transhydrogenase from beef heart purified by fast protein liquid chromatography.
Mitochondrial nicotinamide nucleotide transhydrogenase from beef heart was purified by a novel procedure involving fast protein liquid chromatography and characterized with respect to molecular and catalytic properties. The method is reproducible, gives highly pure transhydrogenase as judged by silver staining, and can be modified to produce large amounts of pure transhydrogenase protein suitable for e.g. sequencing and other protein chemical studies. Transhydrogenase purified by fast protein liquid chromatography is reconstitutively active and pumps protons as indicated by an extensive quenching of 9-aminoacridine fluorescence. Under conditions which generate a proton gradient in the absence of a membrane potential the activity of reconstituted transhydrogenase is close to zero indicating a complete and proper incorporation in the membrane and a preferential regulation of the enzyme by a proton gradient rather than a membrane potential. Treatment of reconstituted transhydrogenase with N,N-dicyclohexylcarbodiimide results in an inhibition of proton pump activity without an effect on uncoupled catalytic activity, suggesting that proton translocation and catalytic activities are not obligatory linked or that this agent separates proton pumping from the catalytic activity.
Topics: Aminacrine; Amino Acids; Aminoacridines; Animals; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Cattle; Dicyclohexylcarbodiimide; Energy Metabolism; Fluorescent Dyes; Kinetics; Liposomes; Mitochondria; Mitochondria, Heart; NADH, NADPH Oxidoreductases; NADP Transhydrogenases; Proton-Translocating ATPases; Submitochondrial Particles
PubMed: 6234316
DOI: No ID Found -
Nucleic Acids Research Aug 1987The DNA unwinding effects of some 9-aminoacridine derivatives were compared under reaction conditions that could be used to study drug-induced topoisomerase II... (Comparative Study)
Comparative Study
The DNA unwinding effects of some 9-aminoacridine derivatives were compared under reaction conditions that could be used to study drug-induced topoisomerase II inhibition. An assay was designed to determine drug-induced DNA unwinding by using L1210 topoisomerase I. 9-aminoacridines could be ranked by decreasing unwinding potency: compound C greater than or equal to 9-aminoacridine greater than o-AMSA greater than or equal to compound A greater than compound B greater than m-AMSA. Ethidium bromide was more potent than any of the 9-aminoacridines. This assay is a fast and simple method to compare DNA unwinding effects of intercalators. It led to the definition of a drug intrinsic unwinding constant (k). An additional finding was that all 9-aminoacridines and ethidium bromide inhibited L1210 topoisomerase I. Enzyme inhibition was detectable at low enzyme concentrations (less than or equal to 1 unit) and when the kinetics of topoisomerase I-mediated DNA relaxation was studied. Topoisomerase I inhibition was not associated with DNA swivelling or cleavage.
Topics: Aminacrine; Aminoacridines; Animals; DNA, Viral; Ethidium; Intercalating Agents; Leukemia L1210; Mice; Neoplasm Proteins; Nucleic Acid Conformation; Structure-Activity Relationship; Topoisomerase I Inhibitors
PubMed: 2819825
DOI: 10.1093/nar/15.16.6713 -
Proceedings of the National Academy of... Sep 1986Frameshift mutations were induced by proflavin in the rIIB gene of bacteriophage T4. rIIB DNA from each of 48 independent frameshifts was inserted into M13mp8 and...
Frameshift mutations were induced by proflavin in the rIIB gene of bacteriophage T4. rIIB DNA from each of 48 independent frameshifts was inserted into M13mp8 and sequenced. Two-thirds of the frameshifts (33/48) lie contiguous to one another in 10 base pairs of the rIIB sequence. This hotspot differs markedly from previously characterized mutagen-induced frameshift hotspots. Distinctive features of the hotspot include the absence of locally repetitive sequences, particularly G X C runs, and the fact that many different sequence changes are induced within the hotspot sequence at appreciable frequencies. Among the 33 mutants at the hotspot, 8 distinguishable DNA sequence changes were seen. All of the mutations were deletions of a single base or duplications of one or more bases. Duplications were more frequent than deletions. The patterns of the base sequence changes suggest that two specific phosphodiester bonds within the hotspot sequence are sites at which proflavin-induced mutation is initiated.
Topics: Acridines; Aminacrine; Aminoacridines; Base Sequence; DNA, Viral; Mutagens; Mutation; Nitrogen Mustard Compounds; Proflavine; T-Phages
PubMed: 3462738
DOI: 10.1073/pnas.83.18.6954 -
Genetics Dec 1991As the most nucleophilic site in DNA, the guanine N7 atom is a major site of adduction by a large number of alkylating mutagens and carcinogens. Aflatoxin B1, a powerful...
As the most nucleophilic site in DNA, the guanine N7 atom is a major site of adduction by a large number of alkylating mutagens and carcinogens. Aflatoxin B1, a powerful mutagen, is believed to act through its reaction with this DNA site. On the basis of the specificity of base substitutions induced by various adduct forms of aflatoxin, we have proposed that bulky guanine N7 adducts elicit base substitutions by two mechanisms. The first mechanism is similar to that observed for a number of bulky noninstructive lesions, whereas the second mechanism invokes mispairing between N7-adducted guanine and thymine. A prediction of the mispairing hypothesis is that diverse bulky guanine N7 adducts (regardless of structural similarities with the aflatoxins) should induce predominantly G-to-A transitions. Accordingly, we have recently observed that base substitutions induced by the acridine half-mustard ICR-191 in the M13 double-stranded DNA transfection system are predominantly G:C-to-A:T transitions. Here, by transfecting ICR-191-treated M13 AB28 single-stranded DNA into Escherichia coli, we show that base substitutions are predominantly targeted to guanines. Since the N7-adducted-guanine:thymine mispairing is proposed to require N1 deprotonation promoted by the primary N7 lesion, guanine imidazole ring-opening should abolish this mispairing property, and thereby alter the specificity of mutagenesis. Here, we show that the incubation of ICR-191-treated RF DNA at pH 10.5 results in a significant reversal of the specificity of G:C-targeted substitutions such that G-to-T transversions predominated over G-to-A transitions.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Aminacrine; Bacteriophages; Base Composition; Base Sequence; DNA Damage; DNA, Single-Stranded; DNA, Viral; Escherichia coli; Frameshift Mutation; Guanine; Hydrogen-Ion Concentration; Molecular Sequence Data; Molecular Structure; Mutagenesis, Site-Directed; Mutagens; Nitrogen Mustard Compounds; Transfection
PubMed: 1783299
DOI: 10.1093/genetics/129.4.981