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Losi MA, Izzo R, Mancusi C, Wang W, Roman MJ, Lee ET, Howard BH, Devereux RB, De Simone G. P3192Depressed myocardial energetic efficiency is associated with increased risk of incident heart failure: the strong heart study. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy563.p3192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- M A Losi
- Federico II University of Naples, Advanced Biomedical Sciences, Naples, Italy
| | - R Izzo
- Federico II University Hospital, Department of Translational Medicine, Naples, Italy
| | - C Mancusi
- Federico II University of Naples, Advanced Biomedical Sciences, Naples, Italy
| | - W Wang
- University of Oklahoma, Oklahoma City, United States of America
| | - M J Roman
- Weill Cornell Medical College, New York, United States of America
| | - E T Lee
- University of Oklahoma, Oklahoma City, United States of America
| | - B H Howard
- Medstar Research Institute, Washington, United States of America
| | - R B Devereux
- Weill Cornell Medical College, New York, United States of America
| | - G De Simone
- Federico II University of Naples, Hypertension Research Center, Naples, Italy
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Bassuk NL, Howard BH. A Positive Correlation Between Endogenous Root-Inducing Cofactor Activity in Vacuum-Extracted Sap and Seasonal Changes in Rooting of M.26 Winter Apple Cuttings. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/00221589.1981.11515006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Howard BH, Ridout MS. Rooting potential in plum hardwood cuttings: II. Relationships between shoot variables and rooting in cuttings from different sources. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/00221589.1991.11516199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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5
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Bassuk NL, Howard BH. Factors Affecting the Use of Mung Bean (Vigna RadiataL. Wilczek) Cuttings as a Bioassay for Root-Promoting Substances. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/00221589.1981.11515005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Howard BH, Skene DS, Coles JS. The effects of different grafting methods upon the development of one-year-old nursery apple trees. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/00221589.1974.11514581] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Bassuk NL, Hunter LD, Howard BH. The Apparent Involvement of Polyphenol Oxidase and Phloridzin in the Production of Apple Rooting Cofactors. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/00221589.1981.11515007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Natesakhawat S, Means NC, Howard BH, Smith M, Abdelsayed V, Baltrus JP, Cheng Y, Lekse JW, Link D, Morreale BD. Improved benzene production from methane dehydroaromatization over Mo/HZSM-5 catalysts via hydrogen-permselective palladium membrane reactors. Catal Sci Technol 2015. [DOI: 10.1039/c5cy00934k] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Catalytic Pd membrane reactors improve C6H6 yield compared to fixed-bed reactors.
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Affiliation(s)
- S. Natesakhawat
- National Energy Technology Laboratory
- United States Department of Energy
- Pittsburgh
- USA
- Department of Chemical and Petroleum Engineering
| | - N. C. Means
- National Energy Technology Laboratory
- United States Department of Energy
- Pittsburgh
- USA
- AECOM
| | - B. H. Howard
- National Energy Technology Laboratory
- United States Department of Energy
- Pittsburgh
- USA
| | - M. Smith
- National Energy Technology Laboratory
- United States Department of Energy
- Morgantown
- USA
- AECOM
| | - V. Abdelsayed
- National Energy Technology Laboratory
- United States Department of Energy
- Morgantown
- USA
- AECOM
| | - J. P. Baltrus
- National Energy Technology Laboratory
- United States Department of Energy
- Pittsburgh
- USA
| | - Y. Cheng
- National Energy Technology Laboratory
- United States Department of Energy
- Pittsburgh
- USA
| | - J. W. Lekse
- National Energy Technology Laboratory
- United States Department of Energy
- Pittsburgh
- USA
- AECOM
| | - D. Link
- National Energy Technology Laboratory
- United States Department of Energy
- Pittsburgh
- USA
| | - B. D. Morreale
- National Energy Technology Laboratory
- United States Department of Energy
- Pittsburgh
- USA
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Paglieri SN, Wermer JR, Buxbaum RE, Ciocco MV, Howard BH, Morreale BD. Development of membranes for hydrogen separation: Pd coated V–10Pd. ACTA ACUST UNITED AC 2013. [DOI: 10.1179/174892409x427931] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Soong Y, Dilmore RM, Hedges SW, Howard BH, Romanov V. Utilization of Multiple Waste Streams for Acid Gas Sequestration and Multi-Pollutant Control. Chem Eng Technol 2012. [DOI: 10.1002/ceat.201100341] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Howard BH, Raistrick H. Studies in the biochemistry of micro-organisms. 81. The colouring matters of Penicillium islandicum Sopp. Part 2. Chrysophanic acid, 4:5-dihydroxy-2-methylanthraquinone. Biochem J 2006; 46:49-53. [PMID: 16748635 PMCID: PMC1275079 DOI: 10.1042/bj0460049] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- B H Howard
- Department of Biochemistry, London School of Hygiene and Tropical Medicine, University of London
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McAlister AL, Howard BH. Cigarette taxes and their proposed uses: support among smokers and non-smokers in different income groups in Texas. Tob Control 2005; 14:213-4. [PMID: 15923473 PMCID: PMC1748045 DOI: 10.1136/tc.2005.011676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Russanova VR, Hirai TH, Tchernov AV, Howard BH. Mapping Development-Related and Age-Related Chromatin Remodeling by a High Throughput ChIP-HPLC Approach. J Gerontol A Biol Sci Med Sci 2005. [DOI: 10.1093/gerona/60.4.411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Bustamante F, Enick RM, Killmeyer RP, Howard BH, Rothenberger KS, Cugini AV, Morreale BD, Ciocco MV. Uncatalyzed and wall-catalyzed forward water-gas shift reaction kinetics. AIChE J 2005. [DOI: 10.1002/aic.10396] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Bustamante F, Enick RM, Cugini A, Killmeyer RP, Howard BH, Rothenberger KS, Ciocco MV, Morreale BD, Chattopadhyay S, Shi S. High-temperature kinetics of the homogeneous reverse water-gas shift reaction. AIChE J 2004. [DOI: 10.1002/aic.10099] [Citation(s) in RCA: 172] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Qin G, Takenaka T, Telsch K, Kelley L, Howard T, Levade T, Deans R, Howard BH, Malech HL, Brady RO, Medin JA. Preselective gene therapy for Fabry disease. Proc Natl Acad Sci U S A 2001; 98:3428-33. [PMID: 11248095 PMCID: PMC30670 DOI: 10.1073/pnas.061020598] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fabry disease is a lipid storage disorder resulting from mutations in the gene encoding the enzyme alpha-galactosidase A (alpha-gal A; EC ). We previously have demonstrated long-term alpha-gal A enzyme correction and lipid reduction mediated by therapeutic ex vivo transduction and transplantation of hematopoietic cells in a mouse model of Fabry disease. We now report marked improvement in the efficiency of this gene-therapy approach. For this study we used a novel bicistronic retroviral vector that engineers expression of both the therapeutic alpha-gal A gene and the human IL-2Ralpha chain (huCD25) gene as a selectable marker. Coexpression of huCD25 allowed selective immunoenrichment (preselection) of a variety of transduced human and murine cells, resulting in enhanced intracellular and secreted alpha-gal A enzyme activities. Of particular significance for clinical applicability, mobilized CD34(+) peripheral blood hematopoietic stem/progenitor cells from Fabry patients have low-background huCD25 expression and could be enriched effectively after ex vivo transduction, resulting in increased alpha-gal A activity. We evaluated effects of preselection in the mouse model of Fabry disease. Preselection of transduced Fabry mouse bone marrow cells elevated the level of multilineage gene-corrected hematopoietic cells in the circulation of transplanted animals and improved in vivo enzymatic activity levels in plasma and organs for more than 6 months after both primary and secondary transplantation. These studies demonstrate the potential of using a huCD25-based preselection strategy to enhance the clinical utility of ex vivo hematopoietic stem/progenitor cell gene therapy of Fabry disease and other disorders.
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Affiliation(s)
- G Qin
- Department of Medicine, University of Illinois, Chicago, IL 60607, USA
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20
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Humphrey GW, Wang Y, Russanova VR, Hirai T, Qin J, Nakatani Y, Howard BH. Stable histone deacetylase complexes distinguished by the presence of SANT domain proteins CoREST/kiaa0071 and Mta-L1. J Biol Chem 2001; 276:6817-24. [PMID: 11102443 DOI: 10.1074/jbc.m007372200] [Citation(s) in RCA: 265] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human histone deacetylases I (HDAC1) and II (HDAC2) are homologous proteins (84% identity) that catalyze release of acetyl groups from modified N-terminal lysines of core histones. Histone deacetylation is correlated with both transient and persistent states of transcriptional inactivity (i.e. silencing) in many eukaryotes. In this study, we analyzed complexes containing HDAC1 and HDAC2 to identify the proteins most stably associated with these deacetylases. Complex cI (9.5 S) contained transcriptional corepressor CoREST/kiaa0071 and a protein homologous to FAD-dependent oxidoreductases, kiaa0601. Complex cII (15 S) contained >/=15 proteins, including CHD3/4 (Mi-2), Mta-L1, RbAp48/46, and MBD3, characteristic of vertebrate nucleosome-remodeling complexes. Under native conditions, cI and cII may contain HDAC1, HDAC2 or both; these can be dissociated to cI and cII core complexes containing only HDAC1 or HDAC2. The (m)CpG-binding protein MBD2 was associated only with the HDAC1 cII core complex. A model is proposed in which HDAC1 core complexes can be targeted to methylated DNA via MBD2 with recruitment of HDAC2 occurring through formation of HDAC1/2 cII dimers. We note that the cI component CoREST/kiaa0071 and the cII component Mta-L1 share a region of homology that includes a SANT domain; this domain may play a role in complex assembly.
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Affiliation(s)
- G W Humphrey
- Laboratory of Molecular Growth Regulation, NICHD, National Institutes of Health, Bethesda, Maryland 20892-2753, USA
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Sasaki S, Lesoon-Wood LA, Dey A, Kuwata T, Weintraub BD, Humphrey G, Yang WM, Seto E, Yen PM, Howard BH, Ozato K. Ligand-induced recruitment of a histone deacetylase in the negative-feedback regulation of the thyrotropin beta gene. EMBO J 1999; 18:5389-98. [PMID: 10508171 PMCID: PMC1171608 DOI: 10.1093/emboj/18.19.5389] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have investigated ligand-dependent negative regulation of the thyroid-stimulating hormone beta (TSHbeta) gene. Thyroid hormone (T3) markedly repressed activity of the TSHbeta promoter that had been stably integrated into GH(3 )pituitary cells, through the conserved negative regulatory element (NRE) in the promoter. By DNA affinity binding assay, we show that the NRE constitutively binds to the histone deacetylase 1 (HDAC1) present in GH(3 )cells. Significantly, upon addition of T3, the NRE further recruited the thyroid hormone receptor (TRbeta) and another deacetylase, HDAC2. This recruitment coincided with an alteration of in vivo chromatin structure, as revealed by changes in restriction site accessibility. Supporting the direct interaction between TR and HDAC, in vitro assays showed that TR, through its DNA binding domain, strongly bound to HDAC2. Consistent with the role for HDACs in negative regulation, an inhibitor of the enzymes, trichostatin A, attenuated T3-dependent promoter repression. We suggest that ligand-dependent histone deacetylase recruitment is a mechanism of the negative-feedback regulation, a critical function of the pituitary-thyroid axis.
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Affiliation(s)
- S Sasaki
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2753, USA
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22
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Kotani T, Zhang X, Schiltz RL, Ogryzko VV, Howard T, Swanson MJ, Vassilev A, Zhang H, Yamauchi J, Howard BH, Qin J, Nakatani Y. TBP-associated factors in the PCAF histone acetylase complex. Cold Spring Harb Symp Quant Biol 1999; 63:493-9. [PMID: 10384313 DOI: 10.1101/sqb.1998.63.493] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- T Kotani
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA
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Lee AC, Fenster BE, Ito H, Takeda K, Bae NS, Hirai T, Yu ZX, Ferrans VJ, Howard BH, Finkel T. Ras proteins induce senescence by altering the intracellular levels of reactive oxygen species. J Biol Chem 1999; 274:7936-40. [PMID: 10075689 DOI: 10.1074/jbc.274.12.7936] [Citation(s) in RCA: 485] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Human diploid fibroblasts eventually lose the capacity to replicate in culture and enter a viable but nonproliferative state of senescence. Recently, it has been demonstrated that retroviral-mediated gene transfer into primary fibroblasts of an activated ras gene (V12ras) rapidly accelerates development of the senescent phenotype. Using this in vitro system, we have sought to define the mediators of Ras-induced senescence. We demonstrate that expression of V12Ras results in an increase in intracellular and in particular, mitochondrial reactive oxygen species. The ability of V12Ras to induce growth arrest and senescence is shown to be partially inhibited by coexpression of an activated rac1 gene. A more dramatic rescue of V12Ras-expressing cells is demonstrated when the cells are placed in a low oxygen environment, a condition in which reactive oxygen species production is inhibited. In addition, in a 1% oxygen environment, Ras is unable to trigger an increase in the level of the cyclin-dependent kinase inhibitor p21 or to activate the senescent program. Under normoxic (20% O2) conditions, the V12Ras senescent phenotype is demonstrated to be unaffected by scavengers of superoxide but rescued by scavengers of hydrogen peroxide. These results suggest that in normal diploid cells, Ras proteins regulate oxidant production and that a rise in intracellular H2O2 represents a critical signal mediating replicative senescence.
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Affiliation(s)
- A C Lee
- Cardiology Branch, National Institutes of Health, Bethesda, Maryland 20892, USA
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Benkirane M, Chun RF, Xiao H, Ogryzko VV, Howard BH, Nakatani Y, Jeang KT. Activation of integrated provirus requires histone acetyltransferase. p300 and P/CAF are coactivators for HIV-1 Tat. J Biol Chem 1998; 273:24898-905. [PMID: 9733796 DOI: 10.1074/jbc.273.38.24898] [Citation(s) in RCA: 230] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A unique aspect of the retrovirus life cycle is the obligatory integration of the provirus into host cell chromosomes. Unlike viruses that do not integrate, retroviruses must conserve an ability to activate transcription from a chromatin context. Human immunodeficiency virus (HIV)-1 encodes an unusual and an unusually potent transcriptional transactivator, Tat, which binds to a nascent viral leader RNA, TAR. The action of Tat has been well studied in various reductive model systems; however, the physiological mechanism through which Tat gains access to chromatin-associated proviral long terminal repeats (LTRs) is not understood. We show here that a nuclear histone acetyltransferase activity associates with Tat. Intracellularly, we found that Tat forms a ternary complex with p300 and P/CAF, two histone acetyltransferases (HATs). A murine cell defect in Tat transactivation of the HIV-1 LTR was linked to the reduced abundance of p300 and P/CAF. Thus, overexpression of p300 and P/CAF reconstituted Tat transactivation of the HIV-1 LTR in NIH3T3 cells to a level similar to that observed for human cells. By using transdominant p300 or P/CAF mutants that lack enzymatic activity, we delineated a requirement for the HAT component from the latter but not the former in Tat function. Finally, we observed that Tat-associated HAT is preferentially important for transactivation of integrated, but not unintegrated, HIV-1 LTR.
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Affiliation(s)
- M Benkirane
- Molecular Virology Section, Laboratory of Molecular Microbiology, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA
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Abstract
PCAF histone acetylase plays a role in regulation of transcription, cell cycle progression, and differentiation. Here, we show that PCAF is found in a complex consisting of more than 20 distinct polypeptides. Strikingly, some polypeptides are identical to TBP-associated factors (TAFs), which are subunits of TFIID. Like TFIID, histone fold-containing factors are present within the PCAF complex. The histone H3- and H2B-like subunits within the PCAF complex are identical to those within TFIID, namely, hTAF(II)31 and hTAF(II)20/15, respectively. The PCAF complex has a novel histone H4-like subunit with similarity to hTAF(II)80 that interacts with the histone H3-like domain of hTAF(II)31. Moreover, the PCAF complex has a novel subunit with WD40 repeats having a similarity to hTAF(II)100.
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Affiliation(s)
- V V Ogryzko
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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Engleka KA, Lewis EW, Howard BH. Mechanisms of replication-deficient vaccinia virus/T7 RNA polymerase hybrid expression: effect of T7 RNA polymerase levels and alpha-amanitin. Virology 1998; 243:331-9. [PMID: 9568032 DOI: 10.1006/viro.1998.9070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Components of the eukaryotic vaccinia virus/T7 RNA polymerase hybrid expression system were assessed using recombinant and nonrecombinant forms of modified vaccinia Ankara (MVA), a replication-deficient vaccinia virus strain. Recombinant MVA virus expressing T7 RNA polymerase (Wyatt, L. S., Moss, B., and Rozenblatt, S. (1995). Virology 210, 202-205) stimulated high levels of expression from a T7 promoter-chloramphenicol acetyltransferase (CAT) reporter. Most, but not all, of the virally induced expression was T7 RNA polymerase and T7 promoter dependent, with no viral enhancement of translation of T7 transcripts. The efficacy of supplying T7 RNA polymerase expression from nonviral sources was evaluated using a self-amplifying T7 RNA polymerase autogene or an inducible T7 RNA polymerase expression vector. The latter modes yielded CAT activity dependent on T7 RNA polymerase expression; however, expression required viral factors independent of T7 RNA polymerase and did not reach that attained using the recombinant virus. In further experiments, MVA-induced T7 RNA polymerase expression was upregulated by alpha-amanitin, an inhibitor of eukaryotic polymerases. This indicates that MVA/T7 RNA polymerase hybrid expression may be rendered still more efficient by ameliorating transcriptional interference due to an alpha-amanitin-sensitive eukaryotic factor(s).
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Affiliation(s)
- K A Engleka
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2753, USA.
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Puri PL, Sartorelli V, Yang XJ, Hamamori Y, Ogryzko VV, Howard BH, Kedes L, Wang JY, Graessmann A, Nakatani Y, Levrero M. Differential roles of p300 and PCAF acetyltransferases in muscle differentiation. Mol Cell 1997; 1:35-45. [PMID: 9659901 DOI: 10.1016/s1097-2765(00)80005-2] [Citation(s) in RCA: 339] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PCAF is a histone acetyltransferase that associates with p300/CBP and competes with E1A for access to them. While exogenous expression of PCAF potentiates both MyoD-directed transcription and myogenic differentiation, PCAF inactivation by anti-PCAF antibody microinjection prevents differentiation. MyoD interacts directly with both p300/CBP and PCAF, forming a multimeric protein complex on the promoter elements. Viral transforming factors that interfere with muscle differentiation disrupt this complex without affecting the MyoD-DNA interaction, indicating functional significance of the complex formation. Exogenous expression of PCAF or p300 promotes p21 expression and terminal cell-cycle arrest. Both of these activities are dependent on the histone acetyltransferase activity of PCAF, but not on that of p300. These results indicate that recruitment of histone acetyltransferase activity of PCAF by MyoD, through p300/CBP, is crucial for activation of the myogenic program.
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MESH Headings
- Acetyl-CoA C-Acyltransferase/metabolism
- Acetyltransferases/metabolism
- Animals
- Antigens, Viral, Tumor/pharmacology
- CREB-Binding Protein
- Cell Cycle Proteins/metabolism
- Cell Differentiation/physiology
- Cells, Cultured
- E1A-Associated p300 Protein
- Gene Expression Regulation, Developmental/drug effects
- Gene Expression Regulation, Developmental/physiology
- Gene Expression Regulation, Enzymologic/drug effects
- Gene Expression Regulation, Enzymologic/physiology
- Histone Acetyltransferases
- Mice
- Multienzyme Complexes/metabolism
- Muscle Fibers, Skeletal/chemistry
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/enzymology
- Muscle, Skeletal/chemistry
- Muscle, Skeletal/cytology
- Muscle, Skeletal/enzymology
- MyoD Protein/metabolism
- Nuclear Proteins/metabolism
- Nuclear Proteins/pharmacology
- RNA Polymerase II/metabolism
- Saccharomyces cerevisiae Proteins
- Trans-Activators
- Transcription Factors/metabolism
- Transcription Factors/pharmacology
- Transcriptional Activation/physiology
- p300-CBP Transcription Factors
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Affiliation(s)
- P L Puri
- Laboratory of Gene Expression, Fondazione Andrea Cesalpino, Istituto I Clinica Medica, Policlinico Umberto I, University of Rome, La Sapienza, Italy
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Minucci S, Horn V, Bhattacharyya N, Russanova V, Ogryzko VV, Gabriele L, Howard BH, Ozato K. A histone deacetylase inhibitor potentiates retinoid receptor action in embryonal carcinoma cells. Proc Natl Acad Sci U S A 1997; 94:11295-300. [PMID: 9326603 PMCID: PMC23446 DOI: 10.1073/pnas.94.21.11295] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Histone acetylation is thought to have a role in transcription. To gain insight into the role of histone acetylation in retinoid-dependent transcription, we studied the effects of trichostatin A (TSA), a specific inhibitor of histone deacetylase, on P19 embryonal carcinoma cells. We show that coaddition of TSA and retinoic acid (RA) markedly enhances neuronal differentiation in these cells, although TSA alone does not induce differentiation but causes extensive apoptosis. Consistent with the cooperative effect of TSA and RA, coaddition of the two agents synergistically enhanced transcription from stably integrated RA-responsive promoters. The transcriptional synergy by TSA and RA required the RA-responsive element and a functional retinoid X receptor (RXR)/retinoic acid receptor (RAR) heterodimer, both obligatory for RA-dependent transcription. Furthermore, TSA led to promoter activation by an RXR-selective ligand that was otherwise inactive in transcription. In addition, TSA enhanced transcription from a minimum basal promoter, independently of the RA-responsive element. Finally, we show that TSA alone or in combination with RA increases in vivo endonuclease sensitivity within the RA-responsive promoter, suggesting that TSA treatment might alter a local chromatin environment to enhance RXR/RAR heterodimer action. Thus, these results indicate that histone acetylation influences activity of the heterodimer, which is in line with the observed interaction between the RXR/RAR heterodimer and a histone acetylase presented elsewhere.
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Affiliation(s)
- S Minucci
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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29
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Abstract
A new approach to monitoring UV damage and repair in the human genome has been developed. The proposed approach is based on a combination of features unique to interspersed repetitive Alu elements, and the ability of certain DNA lesions to block Taq polymerase-mediated DNA synthesis: namely, the extraordinary abundance of Alu repeats throughout the human genome in conjunction with distinct sequence motifs comprising long runs of T residues which are likely targets for formation of UV lesions. Hence, Taq polymerase-mediated extension synthesis with Alu specific primers was employed to visualize formation of discrete predicted adducts within the element. Several variations of the Alu-primer driven amplification protocol were developed to monitor the following aspects of damage: (i) induction of UV-photoproducts at predicted sites within the Alu sequence, (ii) modification of extension synthesis profiles, (iii) UV dose dependent, quantitative inhibition of Alu-primer driven amplification. The assays reveal sites of predicted Taq polymerase blockage within the Alu sequence, a global decrease in the mean length of extension products, and a measurable reduction in the quantity of extension products that is inversely proportional to UV dose. Thus, the exceptional abundance of Alu repeats and their primary sequence features, in combination with the ability of UV lesions to block elongation by Taq polymerase, provide a novel and sensitive system for detecting UV damage in the human genome. The system detects UV damage at levels that are compatible with cellular DNA repair, and provides a unique amplification-based protocol for probing the overall integrity of human DNA.
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Affiliation(s)
- E W Englander
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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30
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Ogryzko VV, Brinkmann E, Howard BH, Pastan I, Brinkmann U. Antisense inhibition of CAS, the human homologue of the yeast chromosome segregation gene CSE1, interferes with mitosis in HeLa cells. Biochemistry 1997; 36:9493-500. [PMID: 9235994 DOI: 10.1021/bi970236o] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have analyzed the effects on HeLa cells of reduction of the CAS protein, the human homologue to yeast chromosome segregation protein CSE1. Expression of CAS antisense cDNA decreases the amount of CAS protein in HeLa cells and perturbs progression from G2 (retards transition from G2) to G1 in the cell cycle. Increased levels of cyclin B in CAS antisense transfected cells correlated with an arrest in G2 phase or mitosis. This arrest upon CAS attenuation is consistent with observations that yeast with CSE1 mutations are defective in mitosis and cyclin B degradation.
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Affiliation(s)
- V V Ogryzko
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Development, and Laboratory of Molecular Biology, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
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31
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Abstract
The p21(WAF1/CIP1/sdi1) gene product (WAF1) inhibits DNA replication in vitro (J. Chen, P. Jackson, M. Kirschner, and A. Dutta, Nature 374:386-388, 1995; S. Waga, G. Hannon, D. Beach, and B. Stillman, Nature 369:574-578, 1994), but in vivo studies on the antiproliferative activity of WAF1 have not resolved G1-phase arrest from potential inhibition of S-phase progression. Here, we demonstrate that elevated WAF1 expression can retard replicative DNA synthesis in vivo. The WAF1-mediated inhibitory effect could be antagonized by cyclin A, cyclin E, or the simian virus 40 small-t antigen with no decrease in the levels of WAF1 protein in transfected cells. Proliferating-cell nuclear antigen (PCNA) overexpression was neither necessary nor sufficient to antagonize WAF1 action. Expression of the N-terminal domain of WAF1, responsible for cyclin-dependent kinase (CDK) interaction, had the same effect as full-length WAF1, while the PCNA binding C terminus exhibited modest activity. We conclude that S-phase progression in mammalian cells is dependent on continuing cyclin and CDK activity and that WAF1 affects S phase primarily through cyclin- and CDK-dependent pathways.
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Affiliation(s)
- V V Ogryzko
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2753, USA
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32
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Thornton AM, Ogryzko VV, Dent A, Sharf R, Levi BZ, Kanno Y, Staudt LM, Howard BH, Ozato K. A dominant negative mutant of an IFN regulatory factor family protein inhibits both type I and type II IFN-stimulated gene expression and antiproliferative activity of IFNs. J Immunol 1996; 157:5145-54. [PMID: 8943426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Type I (alpha,beta) and type II (gamma) IFNs elicit antiproliferative and antiviral activities through two distinct transcription pathways involving 1) IRF family proteins and ISGF3, and 2) STAT1. We have employed a dominant negative strategy to study the role of IRF family proteins in eliciting the biologic activities of IFN. A truncated IRF protein retaining the DNA-binding domain (DBD) of ICSBP (a member of the IRF family) was stably transfected into U937 monocytic cells. Clones expressing DBD had markedly reduced ISRE-binding activity and were defective in expressing several type I IFN-inducible genes. STAT1 was one such type I IFN-inducible gene whose expression was also inhibited in DBD clones. As a result, the expression of several IFN-gamma-inducible genes was also inhibited in these clones, indicating functional coupling of the type I and type II IFN transcription pathways. Furthermore, DBD clones grew more slowly than control clones and were refractory to antiproliferative effects of both types of IFNs. We found that IFN treatment of U937 cells leads to a G1 arrest and an increase in underphosphorylated retinoblastoma gene product. However, IFN treatment did not change the cell cycle profile, nor retinoblastoma gene product phosphorylation state in DBD clones. These data indicate that expression of DBD disrupts cell cycle regulatory mechanisms. Combined with the previously noted failure of DBD clones to elicit antiviral activity, the present work shows that IRF family proteins play an integral part in growth control activities of IFNs.
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Affiliation(s)
- A M Thornton
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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33
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Thornton AM, Ogryzko VV, Dent A, Sharf R, Levi BZ, Kanno Y, Staudt LM, Howard BH, Ozato K. A dominant negative mutant of an IFN regulatory factor family protein inhibits both type I and type II IFN-stimulated gene expression and antiproliferative activity of IFNs. The Journal of Immunology 1996. [DOI: 10.4049/jimmunol.157.11.5145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Type I (alpha,beta) and type II (gamma) IFNs elicit antiproliferative and antiviral activities through two distinct transcription pathways involving 1) IRF family proteins and ISGF3, and 2) STAT1. We have employed a dominant negative strategy to study the role of IRF family proteins in eliciting the biologic activities of IFN. A truncated IRF protein retaining the DNA-binding domain (DBD) of ICSBP (a member of the IRF family) was stably transfected into U937 monocytic cells. Clones expressing DBD had markedly reduced ISRE-binding activity and were defective in expressing several type I IFN-inducible genes. STAT1 was one such type I IFN-inducible gene whose expression was also inhibited in DBD clones. As a result, the expression of several IFN-gamma-inducible genes was also inhibited in these clones, indicating functional coupling of the type I and type II IFN transcription pathways. Furthermore, DBD clones grew more slowly than control clones and were refractory to antiproliferative effects of both types of IFNs. We found that IFN treatment of U937 cells leads to a G1 arrest and an increase in underphosphorylated retinoblastoma gene product. However, IFN treatment did not change the cell cycle profile, nor retinoblastoma gene product phosphorylation state in DBD clones. These data indicate that expression of DBD disrupts cell cycle regulatory mechanisms. Combined with the previously noted failure of DBD clones to elicit antiviral activity, the present work shows that IRF family proteins play an integral part in growth control activities of IFNs.
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Affiliation(s)
- A M Thornton
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - V V Ogryzko
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - A Dent
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - R Sharf
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - B Z Levi
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Y Kanno
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - L M Staudt
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - B H Howard
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - K Ozato
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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34
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Abstract
p300/CBP is a transcriptional adaptor that integrates signals from many sequence-specific activators via direct interactions. Various cellular and viral factors target p300/CBP to modulate transcription and/or cell cycle progression. One such factor, the cellular p300/CBP associated factor (PCAF), possesses intrinsic histone acetyltransferase activity. Here, we demonstrate that p300/CBP is not only a transcriptional adaptor but also a histone acetyltransferase. p300/CBP represents a novel class of acetyltransferases in that it does not have the conserved motif found among various other acetyltransferases. p300/CBP acetylates all four core histones in nucleosomes. These observations suggest that p300/CBP acetylates nucleosomes in concert with PCAF.
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Affiliation(s)
- V V Ogryzko
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2753, USA
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35
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Ogryzko VV, Hirai TH, Russanova VR, Barbie DA, Howard BH. Human fibroblast commitment to a senescence-like state in response to histone deacetylase inhibitors is cell cycle dependent. Mol Cell Biol 1996; 16:5210-8. [PMID: 8756678 PMCID: PMC231521 DOI: 10.1128/mcb.16.9.5210] [Citation(s) in RCA: 208] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Human diploid fibroblasts (HDF) complete a limited number of cell divisions before entering a growth arrest state that is termed replicative senescence. Two histone deacetylase inhibitors, sodium butyrate and trichostatin A, dramatically reduce the HDF proliferative life span in a manner that is dependent on one or more cell doublings in the presence of these agents. Cells arrested and subsequently released from histone deacetylase inhibitors display markers of senescence and exhibit a persistent G1 block but remain competent to initiate a round of DNA synthesis in response to simian virus 40 T antigen. Average telomere length in prematurely arrested cells is greater than in senescent cells, reflecting a lower number of population doublings completed by the former. Taken together, these results support the view that one component of HDF senescence mimics a cell cycle-dependent drift in differentiation state and that propagation of HDF in histone deacetylase inhibitors accentuates this component.
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Affiliation(s)
- V V Ogryzko
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, Bethesda, Maryland 20892-2753, USA
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36
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Abstract
The adenoviral oncoprotein E1A induces progression through the cell cycle by binding to the products of the p300/CBP and retinoblastoma gene families. A new cellular p300/CBP-associated factor (P/CAF) having intrinsic histone acetylase activity has been identified that competes with E1A. Exogenous expression of P/CAF in HeLa cells inhibits cell-cycle progression and counteracts the mitogenic activity of E1A. E1A disturbs the normal cellular interaction between p300/CBP and its associated histone acetylase.
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Affiliation(s)
- X J Yang
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2753, USA
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37
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Horn V, Minucci S, Ogryzko VV, Adamson ED, Howard BH, Levin AA, Ozato K. RAR and RXR selective ligands cooperatively induce apoptosis and neuronal differentiation in P19 embryonal carcinoma cells. FASEB J 1996; 10:1071-7. [PMID: 8801169 DOI: 10.1096/fasebj.10.9.8801169] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Retinoids cause differentiation in embryonal carcinoma (EC) cells, thus mimicking events in mammalian development. Here, we show that retinoids also cause apoptosis in P19 EC cells. Characteristic DNA fragmentation was observed within 36 h after addition of retinoic acid (RA). Synthetic retinoids that are selective for RA receptors (RAR) were also effective in inducing apoptosis, whereas RXR selective ligands were without effect. The combination of RAR and RXR ligands resulted in a synergistic increase in apoptotic cell death. As with apoptosis, neuronal differentiation of P19 cells was synergistically induced by the combination of RAR and RXR ligands. Data obtained with an RAR antagonist and with P19 cells carrying a dominant negative RXR indicate that the two processes are receptor mediated. Together, our results indicate that retinoid-induced apoptosis and neuronal differentiation are closely coupled, and that both RAR and RXR play a role in these processes as active receptors for their respective ligands.
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Affiliation(s)
- V Horn
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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38
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Englander EW, Howard BH. A naturally occurring T14A11 tract blocks nucleosome formation over the human neurofibromatosis type 1 (NF1)-Alu element. J Biol Chem 1996; 271:5819-23. [PMID: 8621451 DOI: 10.1074/jbc.271.10.5819] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The nature of chromatin organization over Alu repetitive elements is of interest with respect to the maintenance of their transcriptional silencing as well as their potential to influence local chromatin structure. We previously demonstrated that the pattern of nucleosomal organization over Alu elements in native chromatin is specific and similar to the pattern observed with an in vitro reconstituted Alu template. This pattern, distinguished by a nucleosome centered over the 5 -end of the Alu element, is associated with repression of polymerase III-dependent transcription in vitro (Englander, E. W., Wolffe, A. P., and Howard, B. H. (1993) J. Biol. Chem. 268, 19565-19573; Englander, E. W., and Howard, B. H. (1995) J. Biol. Chem. 270, 10091-10096). In the current study, additional templates representing both evolutionarily old and young Alu subfamilies were found to direct a similar pattern of nucleosome assembly, consistent with the view that nucleosome positioning in vitro is shared by a majority of Alus. We discovered however, that the specific nucleosome positioning pattern was disrupted over one member of a young Alu subfamily, which recently transposed immediately downstream to a T14A11 sequence in the neurofibromatosis type 1 locus (Wallace, M. R., Andersen, L. B., Saulino, A. M., Gregory, P. E., Glover, T. W., and Collins, F. S. (1991) Nature 353, 864-866). Upon removal of this sequence motif, the expected pattern of assembly was restored to the neurofibromatosis type 1-Alu template. This finding indicates that, at least in vitro, certain sequences can override the propensity for positioning nucleosomes that is inherent to Alu elements. The finding also raises the possibility that a similar situation may occur in vivo, with potential implications for understanding mechanisms by which certain Alu elements may evade chromatin-mediated transcriptional silencing.
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Affiliation(s)
- E W Englander
- Laboratory of Molecular Growth Regulation, NICHD, National Institutes of Health, Bethesda, Maryland 20892-2753, USA
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39
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Humphrey GW, Englander EW, Howard BH. Specific binding sites for a pol III transcriptional repressor and pol II transcription factor YY1 within the internucleosomal spacer region in primate Alu repetitive elements. Gene Expr 1996; 6:151-68. [PMID: 9041122 PMCID: PMC6148310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/1996] [Accepted: 09/30/1996] [Indexed: 02/03/2023]
Abstract
Alu interspersed repetitive elements possess internal RNA polymerase III promoters that are transcribed in vitro and in transfected mouse cells but are nearly silent in human HeLa cells. Transcriptional repression of these elements is to some extent reversible, as pol III-dependent Alu expression can be induced with herpes simplex or adenovirus. To assess whether sequence-specific DNA binding proteins might contribute to Alu transcriptional silencing, we examined the internucleosomal spacer region surrounding the B box of the Alu pol III promoter in HeLa cell nuclei for evidence of proteins bound at specific sites in vivo. We identified a DNase I-hypersensitive site 5' to the B box and a DNase I-resistant region 3' to the B box in nuclei. An Alu-specific repressor binds to a 5-bp inverted repeat motif overlapping the 5' end of the TFIIIC binding site and may inhibit pol III transcription through competitive displacement. The level of Alu-specific pol III repressor activity is significantly reduced in adenovirus-infected HeLa cells, suggesting that the repressor may contribute to Alu transcriptional silencing in vivo. The 3' DNase I-resistant region coincided with a binding site for the pol II transcription factor YY1 in vitro. YY1 is one of the major proteins in HeLa cells having binding specificity for Alu elements. YY1 bound to tandem arrays of genomic Alu elements may play a role in chromatin organization and silencing.
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Affiliation(s)
- G W Humphrey
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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40
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Abstract
Replicative senescence of human diploid fibroblasts (HDF) cultured in vitro is characterized by a progressive and irreversible loss of responsiveness to mitogenic stimulation by serum. While some constraints have been placed on the nature of HDF senescence, its underlying molecular mechanism(s) remain obscure. Here, the possibility is considered that defects in cell cycle-coupled reassembly of repressive chromatin domains may contribute to HDF senescence. Features of this model are discussed in relation to established models of HDF senescence based on telomere shortening and loss of DNA methylation.
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Affiliation(s)
- B H Howard
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2753, USA
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41
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Russanova VR, Driscoll CT, Howard BH. Adenovirus type 2 preferentially stimulates polymerase III transcription of Alu elements by relieving repression: a potential role for chromatin. Mol Cell Biol 1995; 15:4282-90. [PMID: 7623822 PMCID: PMC230667 DOI: 10.1128/mcb.15.8.4282] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The number of Alu transcripts that accumulate in HeLa and other human cells is normally very low; however, infection with adenovirus type 5 increases the expression of Alu elements dramatically, indicating that the potential for polymerase III (pol III)-dependent Alu transcription in vivo is far greater than generally observed (B. Panning and J.R. Smiley, Mol. Cell. Biol. 13:3231-3244, 1993). In this study, we employed nuclear run-on in combination with a novel RNase H-based assay to investigate transcription from uninfected and adenovirus type 2-infected nuclei, as well as genomic DNAs from uninfected and infected cells. When performed in the presence of excess uninfected nuclear extract, such assays revealed that (i) the vast majority of transcriptionally competent Alu elements in nuclei are masked from the pol III transcriptional machinery and (ii) the induction of Alu expression upon adenovirus infection can be largely accounted for by an increased availability of these elements to the pol III transcription machinery. We also investigated the role of H1 histone for silencing of Alu genes and, in comparison, mouse B2 repetitive elements. Depletion of H1 led to an approximately 17-fold activation of B2 repetitive elements but did not change Alu transcription relative to that of constitutively expressed 5S rRNA genes. These results are consistent with the view that Alu repeats are efficiently sequestered by chromatin proteins, that such masking cannot be accounted for by nonspecific H1-dependent repression, and that adenovirus infection at least partially overrides the repressive mechanism(s).
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Affiliation(s)
- V R Russanova
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA
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42
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Abstract
Alu sequences are interspersed throughout the genomes of primate cells, occurring singly and in clusters around RNA polymerase II-transcribed genes. Because these repeat elements are capable of positioning nucleosomes in in vitro reconstitutes (Englander, E. W., Wolffe, A. P., and Howard, B. H. (1993) J. Biol. Chem. 268, 19565-19573), we investigated whether they also influence in vivo chromatin structure. When assayed collectively using consensus sequence probes and native chromatin as template, Alu family members were found to confer rotational positioning on nucleosomes or nucleosome-like particles. In particular, a 10-base pair pattern of DNase I nicking that spanned the RNA polymerase III box A promoter motif extended upstream to cover diverse 5'-flanking sequences, suggesting that Alu repeats may influence patterns of nucleosome formation over neighboring regions. Computational analysis of a set of naturally occurring Alu sequences indicated that nucleosome positioning information is intrinsic to these elements. Inasmuch as local chromatin organization influences gene expression, the capacity of Alu sequences to affect chromatin structure as demonstrated here may help to clarify some features of these elements.
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Affiliation(s)
- E W Englander
- Laboratory of Molecular Growth Regulation, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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43
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Affiliation(s)
- S M Jazwinski
- Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, New Orleans
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44
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Abstract
Alu genes are GC-rich, highly repetitive genetic elements whose functions remain unknown. Members of this family are readily transcribed in vitro by RNA polymerase III, but RNA corresponding to only a small sub-set of Alu elements has been found in vivo. Based on the hypothesis that methylation of Alu elements affects their transcription, the transcriptional activity of unmethylated and methylated template DNA was assessed in vitro. It was found that methylation of a single CG site just 5' to Alu functions to stimulate transcription; the base composition in this region also affects transcriptional activity. These results indicate that the methylation state and sequence of DNA flanking Alu elements influence its transcription rate.
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Affiliation(s)
- R L Vorce
- Laboratory of Molecular Growth Regulation, NICHD, NIH, Bethesda, MD
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45
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Abstract
STUDY DESIGN Venous outflow obstruction or congestion has been implicated in the etiology of some lumbar radicular syndromes. Ten cases of epidural varices or variants manifesting themselves as masses within the lumbar spinal canal or adjacent foramina have been seen. OBJECTIVES Diagnosis was made by multiplanar cross-sectional magnetic resonance and computed tomography imaging and confirmed in five patients by operative findings. These venous abnormalities differ from cases of arteriovenous malformations described in the literature. METHOD Surgical treatment consisting of coagulative oblation and/or excision of the lesion was consistently successful in the five patients who underwent operations for recalcitrant symptoms. The other five patients experienced spontaneous resolution of symptoms. Three distinctly different types of these abnormalities have been identified. RESULTS The described entity may account for some previously unexplained or spontaneously resolving cases of lumbar radiculitis. CONCLUSIONS Knowledge of the existence of this condition, its possible etiologies, and its imaging characteristics may assist in its recognition and improved management of patients with it.
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Affiliation(s)
- E N Hanley
- Department of Orthopaedic Surgery, Carolinas Medical Center, Charlotte, North Carolina
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46
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Abstract
Mitogenic activities of simian virus 40 large T and small t antigens were studied in serum-deprived human diploid fibroblasts. Wild-type large T and small t cooperated in stimulating DNA synthesis and in inducing hyperphosphorylation of the Rb gene product (pRb). In contrast, a T antigen mutant defective for pRb binding (Rb- T) possessed no detectable mitogenic activity alone and failed to complement small t in stimulating DNA synthesis. Surprisingly, Rb- T and small t cooperated as strongly as wild-type T and small t with respect to pRb hyperphosphorylation. As a consequence, in two closely related conditions (i.e., stimulation by small t plus wild-type T versus small t plus Rb- T), the fraction of pRb in hyperphosphorylated forms dissociated from the fraction of cells in the S phase. These results indicate that pRb hyperphosphorylation is not always tightly coupled with a commitment to initiate DNA replication.
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Affiliation(s)
- V V Ogryzko
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, Bethesda, Maryland 20892
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47
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Englander EW, Wolffe AP, Howard BH. Nucleosome interactions with a human Alu element. Transcriptional repression and effects of template methylation. J Biol Chem 1993; 268:19565-73. [PMID: 8366099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Alu interspersed repetitive elements possess internal RNA polymerase III promoters which are strongly transcribed in vitro, yet these elements are nearly silent in somatic cells. To examine whether repression by chromatin proteins could contribute to the low level of Alu expression, a conserved Alu element from the fourth intron of the human alpha-fetoprotein gene was reconstituted with purified octamer or tetramer particles. Analysis of reconstitutes revealed that this Alu element directed translational and rotational positioning of octamers as well as tetramers. In vitro transcription experiments with reconstituted templates demonstrated that RNA polymerase III-dependent transcription of the Alu element was profoundly repressed by positioned octamer particles. Furthermore, complete CpG methylation of this template enhanced the capacity of tetramers to repress transcription.
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Affiliation(s)
- E W Englander
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
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48
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Padmanabhan R, Padmanabhan R, Howard T, Gottesman MM, Howard BH. Magnetic affinity cell sorting to isolate transiently transfected cells, multidrug-resistant cells, somatic cell hybrids, and virally infected cells. Methods Enzymol 1993; 218:637-51. [PMID: 7685471 DOI: 10.1016/0076-6879(93)18047-g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- R Padmanabhan
- Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland 20892
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49
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Abstract
We investigated whether changes in expression of RNA polymerase III (pol III) or heterodisperse RNA polymerase II (pol II) transcripts hybridizing to Alu could be detected in Alzheimer's disease (AD). RNA samples obtained from AD and control brain tissues were examined by Northern analysis for Alu and 7SL RNA expression. All RNA samples contained a prominent band of approximately 300 nucleotides which corresponds to 7SL RNA, the Alu-homologous RNA component of the signal recognition particle. In addition, three small (i.e. less than 300 nucleotide) 7SL/Alu-hybridizing transcripts were detected. The two larger of the low molecular weight transcripts hybridized preferentially to the 7SL RNA probe, while the smallest transcript hybridized to the Alu probe. These transcripts and the heterodisperse RNA were variable in quantity and displayed a lack of correlation with AD.
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Affiliation(s)
- T Giordano
- Laboratory of Molecular Growth Regulation, National Institute of Health, National Institute of Child Health and Human Development, Bethesda, MD 20892
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Abstract
GTP-binding proteins (G-proteins) are a family of closely related, yet structurally distinct signal transducing proteins. In this study the presence and relative abundance of several G-proteins and of their corresponding mRNAs were measured in resting and activated human T lymphocytes. We found that T lymphocytes contain RNA coding for Gs, Gi2, and Gi3. No Gi1- and Go-specific RNA could be detected. Membrane fractions of resting and activated lymphocytes were studied in immunoblot experiments. Again, Gs, Gi2, and Gi3, but not Gi1 and Go, were detected. Upon mitogenic activation, a relative increase in mRNA for Gs and Gi3, but not for Gi2 could be demonstrated in Northern blot experiments. Immunoblotting indicated an increase in Gs and Gi3 density in membrane fractions of T cells as well. Paralleling the increase in Gs, we found that activated T cells produce five to seven times more cAMP per cell in response to prostaglandin E2 (PGE2) than resting lymphocytes. Finally, PGE2 binding studies showed that the number of receptors for this hormone increased from 435 +/- 322 to 1035 +/- 357 per cell following in vitro stimulation. We propose that in vitro T cell activation is paralleled by an increase in sensitivity to PGE2-induced cAMP generation. This sensitization is accompanied by both an increase in cell surface PGE2 receptor numbers as well as by increased expression of the signal transducing protein Gs and may physiologically be important for limiting an immune response.
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Affiliation(s)
- W Holter
- Institute of Immunology-Vienna Int. Research Coop. Center (VIRCC), University of Vienna, Austria
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