251
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Cho C, Ge H, Branciforte D, Primakoff P, Myles DG. Analysis of mouse fertilin in wild-type and fertilin beta(-/-) sperm: evidence for C-terminal modification, alpha/beta dimerization, and lack of essential role of fertilin alpha in sperm-egg fusion. Dev Biol 2000; 222:289-95. [PMID: 10837118 DOI: 10.1006/dbio.2000.9703] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [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: 11/22/2022]
Abstract
The sperm surface protein fertilin functions in sperm-egg interaction. On guinea pig and bovine sperm, fertilin is a heterodimer of alpha and beta subunits. Both subunits are initially synthesized as precursors and then proteolytically processed by removing N-terminal domains. Since the mouse is currently the main mammalian species in which fertilization is studied, in the present report, we analyzed the structure, processing, and expression of fertilin in mouse. We found that the processing of mouse fertilin beta occurs during epididymal maturation and involves changes in the cytoplasmic tail domain as well as the N-terminal domains. Although we (R. Yuan et al., 1997, J. Cell Biol. 137, 105-112) and others (M. S. Chen et al., 1999, J. Cell Biol. 144, 549-561) have previously reported that mature fertilin beta is 55-57 kDa, here we show that 55 kDa is an unrelated protein in the sperm extract which cross-reacts with an antibody that recognizes precursor, but not mature, fertilin beta. Comparison of Western blots of wild-type and fertilin beta knockout sperm revealed that authentic, mature fertilin beta is 45 kDa. We also obtained direct evidence that mouse fertilin alpha and beta exist as a heterodimer. In addition, we found that in mice lacking the fertilin beta subunit, fertilin alpha is absent from mature sperm. A widely proposed model for sperm-egg fusion suggests that fertilin alpha is the sperm component that promotes membrane fusion by undergoing a conformational change that exposes a virus-like, hydrophobic fusion peptide. Because sperm lacking fertilin alpha and fertilin beta can fuse with eggs at 50% the wild-type rate, this model is called into question. The results suggest instead that other gamete surface molecules act to promote membrane fusion and that fertilin's role in gamete fusion is in sperm-egg plasma membrane adhesion.
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Affiliation(s)
- C Cho
- Section of Molecular and Cellular Biology, University of California at Davis, Davis, California, 95616, USA
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252
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Ochs RL, Muro Y, Si Y, Ge H, Chan EK, Tan EM. Autoantibodies to DFS 70 kd/transcription coactivator p75 in atopic dermatitis and other conditions. J Allergy Clin Immunol 2000; 105:1211-20. [PMID: 10856157 DOI: 10.1067/mai.2000.107039] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.3] [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: 12/26/2022]
Abstract
BACKGROUND Sera of patients with atopic dermatitis (AD) were found to have autoantibodies that reacted with tissue culture cell substrates in immunohistochemistry to display a characteristic pattern of nuclear distribution of dense fine speckles. The sera also recognized a 70-kd protein on Western immunoblots, and the antigen was termed dense fine speckles 70 kd (DSF70). OBJECTIVE Because spontaneously occurring autoantibodies could be immune responses to proteins that might be participating in the disease process, it was of interest to identify the antigens driving the autoimmune antibody response. METHODS A serum containing high-titer antibodies to DFS70 was used to immunoscreen a complementary (c)DNA expression library to isolate cDNA encoding the antigen. After the cDNA was isolated, this was used to express recombinant protein to determine the prevalence of antibody in AD and other conditions. RESULTS Thirty percent of patients with AD were found to have antibody to recombinant DFS70 in Western immunoblots. Sixteen percent of patients with asthma and 9% of patients with interstitial cystitis had antibodies of the same specificities. The cDNA encoding DFS70 was identical to a transcription coactivator called p75, which had been shown to be required for RNA polymerase II-dependent transcription. Another important finding was that IgE antibodies to DFS70 were also present in AD sera. CONCLUSION It is suggested that a common basis for the presence of autoantibodies to DFS70 might be related to AD in asthma, interstitial cystitis, and other conditions. A possible role of this antigen-antibody system in pathogenesis remains to be demonstrated, but it appears to be a marker for a subset of patients with AD.
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Affiliation(s)
- R L Ochs
- W. M. Keck Autoimmune Disease Center, Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
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253
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Zhou M, Kashanchi F, Jiang H, Ge H, Brady JN. Phosphorylation of the RAP74 subunit of TFIIF correlates with Tat-activated transcription of the HIV-1 long terminal repeat. Virology 2000; 268:452-60. [PMID: 10704353 DOI: 10.1006/viro.1999.0177] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [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: 11/22/2022]
Abstract
Transcription from the HIV-1 long terminal repeat (LTR) is regulated by the viral transactivator Tat, which increases RNA polymerase II (RNAP II) processivity. Previous reports have demonstrated that phosphorylation of the RNAP II carboxy-terminal domain by TFIIH and P-TEFb is important for Tat transactivation. Our present results demonstrate that phosphorylation of the RAP74 subunit of TFIIF is also an important step in Tat transactivation. Interestingly, while the general transcription factor TFIIF is required for both basal and Tat-activated transcription, phosphorylation of the RAP74 subunit occurs in the presence of Tat and correlates with a high level of transcription activity. Using a biotinylated DNA template transcription assay, we provide evidence that RAP74 is phosphorylated by TAF(II)250 during Tat-activated transcription. Depletion of RAP74 from the HeLa nuclear extract inhibited HIV-1 LTR-driven basal transcription and Tat transactivation. The addition of TFIIF, reconstituted from recombinant RAP30 and RAP74, to the depleted HeLa nuclear extract resulted in restoration of Tat transactivation. Of importance, the exogenous RAP74 was rapidly phosphorylated in the presence of Tat. These results suggest that RAP74 phosphorylation is one important step, of several, in the Tat transactivation cascade.
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Affiliation(s)
- M Zhou
- Virus Tumor Biology Section, National Cancer Institute, Bethesda, Maryland, 20892, USA
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254
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Schang LM, Hwang GJ, Dynlacht BD, Speicher DW, Bantly A, Schaffer PA, Shilatifard A, Ge H, Shiekhattar R. Human PC4 is a substrate-specific inhibitor of RNA polymerase II phosphorylation. J Biol Chem 2000; 275:6071-4. [PMID: 10692395 DOI: 10.1074/jbc.275.9.6071] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [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: 01/07/2023] Open
Abstract
The activity of cyclin-dependent protein kinases (cdks) is physiologically regulated by phosphorylation, association with the specific cyclin subunits, and repression by specific cdk inhibitors. All three physiological regulatory mechanisms are specific for one or more cdks, but none is known to be substrate specific. In contrast, synthetic cdk peptide inhibitors that specifically inhibit cdk phosphorylation of only some substrates, "aptamers," have been described. Here, we show that PC4, a naturally occurring transcriptional coactivator, competitively inhibits cdk-1, -2, and -7-mediated phosphorylation of the largest subunit of RNA polymerase II (RNAPII), but it does not inhibit phosphorylation of other substrates of the same kinases. Interestingly, the phosphorylated form of PC4 is devoid of kinase inhibitory activity. We also show that wild-type PC4 but not the kinase inhibitory-deficient mutant of PC4 represses transcription in vivo. Our results point to a novel role for PC4 as a specific inhibitor of RNAPII phosphorylation.
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Affiliation(s)
- L M Schang
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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255
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Abstract
FUSE-binding protein (FBP) binds the single-stranded far upstream element of active c-myc genes, possesses potent transcription activation and repression domains, and is necessary for c-myc expression. A novel 60 kDa protein, the FBP interacting repressor (FIR), blocked activator-dependent, but not basal, transcription through TFIIH. Recruited through FBP's nucleic acid-binding domain, FIR formed a ternary complex with FBP and FUSE. FIR repressed a c-myc reporter via the FUSE. The amino terminus of FIR contained an activator-selective repression domain capable of acting in cis or even in trans in vivo and in vitro. The repression domain of FIR targeted only TFIIH's p89/XPB helicase, required at several stages in transcription, but not factors required for promoter selection. Thus, FIR locks TFIIH in an activation-resistant configuration that still supports basal transcription.
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Affiliation(s)
- J Liu
- Gene Regulation Section, Laboratory of Pathology, National Cancer Institute, Bethesda, Maryland 20892, USA
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256
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Ge H. UPA, a universal protein array system for quantitative detection of protein-protein, protein-DNA, protein-RNA and protein-ligand interactions. Nucleic Acids Res 2000; 28:e3. [PMID: 10606671 PMCID: PMC102535 DOI: 10.1093/nar/28.2.e3] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.7] [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: 01/24/2023] Open
Abstract
Protein-protein interactions have been widely used to study gene expression pathways and may be considered as a new approach to drug discovery. Here I report the development of a universal protein array (UPA) system that provides a sensitive, quantitative, multi-purpose, effective and easy technology to determine not only specific protein-protein interactions, but also specific interactions of proteins with DNA, RNA, ligands and other small chemicals. (i) Since purified proteins are used, the results can be easily interpreted. (ii) UPA can be used multiple times for different targets, making it economically affordable for most laboratories, hospitals and biotechnology companies. (iii) Unlike DNA chips or DNA microarrays, no additional instrumentation is required. (iv) Since the UPA uses active proteins (without denaturation and renaturation), it is more sensitive compared with most existing methods. (v) Because the UPA can analyze hundreds (even thousands on a protein microarray) of proteins in a single experiment, it is a very effective method to screen proteins as drug targets in cancer and other human diseases.
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Affiliation(s)
- H Ge
- Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, The National Institutes of Health, Bethesda, MD 20892, USA.
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257
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Ge H, Wen Y, Yang G, Betz AL. Increased expression of intercellular adhesion molecule-1 in mouse focal cerebral ischemia model. Chin Med J (Engl) 2000; 113:75-9. [PMID: 11775216] [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: 02/23/2023] Open
Abstract
OBJECTIVE To quantitatively measure the temporal profiles of intercellular adhesion molecule-1 (ICAM-1) protein in mouse brain after middle cerebral artery occlusion (MCAO). METHODS Adult male CD-1 mice received 0, 3, 6, 12, 24, 48 and 72 hour(s) of permanent MCAO with an intraluminal suture technique. The degree and the extent of occlusion were determined using a laser Doppler flowmeter. ICAM-1 positive expression in ischemic regions was determined immunohistochemically and ICAM-1 protein was quantitatively measured using immunoprecipitation and Western blot analysis. RESULTS After MCAO, surface cerebral blood flow (CBF) in the ischemic hemisphere decreased to 9%-15% of the baseline in each time point of 7 to 8 animals. There were no significant differences in CBF measurement during occlusion between groups. Immunohistochemistry showed that ICAM-1 positive microvascular endothelial cells were observed both in the ischemic core and in the perifocal region. There was a tendency for increasing expression of ICAM-1 positive microvascular endothelial cells from the ischemic core to the ischemic margin. Western blot analysis showed that ICAM-1 expression in the ischemic hemisphere began to increase 3 h after MCAO, peaked at 6 h to 12 h, and persisted to 72 h. CONCLUSIONS ICAM-1 expression increases in mice with permanent MCAO because ICAM-1 can mediate leukocyte-endothelial adhesion and progression of leukocyte infiltration after permanent focal cerebral ischemia. ICAM-1 is one of the important factors participating in ischemic cerebral damage and pathogenesis of stroke.
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Affiliation(s)
- H Ge
- Institute of Shanghai Immunology, Shanghai Second Medical University, 280 South Chongqing Road, Shanghai 200025, China.
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258
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Kuzmin I, Geil L, Ge H, Bengtsson U, Duh FM, Stanbridge EJ, Lerman MI. Analysis of aberrant methylation of the VHL gene by transgenes, monochromosome transfer, and cell fusion. Oncogene 1999; 18:5672-9. [PMID: 10523847 DOI: 10.1038/sj.onc.1202959] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [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: 11/09/2022]
Abstract
Several tumor suppressor genes were shown to be inactivated by a process involving aberrant de novo methylation of their GC-rich promoters which is usually associated with transcriptional repression. The mechanisms underlying this process are poorly understood. In particular this abnormal methylation may be caused and/or maintained by either deficiency of some trans-acting factor(s) or by various malfunctions acting in cis. Here we studied the nature of aberrant methylation of the von Hippel-Lindau (VHL) disease tumor suppressor gene in a human clear cell renal carcinoma cell line, UOK 121, that contains a silent hypermethylated endogenous VHL allele. First, we transfected unmethylated VHL transgenes, driven by the VHL promoter, into UOK 121 cells. Next, to exclude possible position effects that may influence methylation of the introduced VHL genes, we transferred a single chromosome 3, carrying an apparently normal hypomethylated VHL allele into the UOK 121 cells. Finally, we created somatic cell hybrids between UOK 121 and UMRC 6 cells containing a mutant VHL-expressing hypomethylated allele. In these three experiments both the methylation of the VHL promoter and the transcriptional status of the introduced and endogenous VHL alleles remained unchanged. Our results demonstrate that the putative trans-acting factors present in the UOK 121 and UMRC 6 cells are unable to induce changes in methylation pattern of the VHL alleles in all cell lines and hybrids studied. Taken together, the results indicate that cis-specific local features are pivotal in maintaining and perpetuating aberrant methylation of the VHL CpG island. Contribution of some putative trans-acting factors cannot be excluded during a period when the aberrant VHL methylation pattern was first generated.
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Affiliation(s)
- I Kuzmin
- Intramural Research Support Program, SAIC-Frederick, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, Maryland, MD 21702, USA
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259
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Kim S, Ge H, Ohtaka-Maruyama C, Chepelinsky AB. The transcription factor Sp3 interacts with promoter elements of the lens specific MIP gene. Mol Vis 1999; 5:12. [PMID: 10407063] [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: 02/13/2023] Open
Abstract
PURPOSE To characterize the cis regulatory elements and their interaction with transcription factors responsible for the lens specific expression of the MIP gene, which encodes the Major Intrinsic Protein of the lens fiber membranes. METHODS Study interaction of factors present in newborn mouse lens nuclear extracts with DNA fragments corresponding to mouse MIP gene 5' flanking sequence by electrophoresis mobility shift assay (EMSA) and DNase I footprinting. RESULTS We found a high degree of identity in the first 100 bp of 5' flanking sequence of mice and humans, however, a lower degree of conservation is observed further upstream. We have found by DNase I footprinting analysis that lens specific factors may interact with the first 100 bp of 5' flanking sequence. A domain containing an E box, conserved in mouse and human, may interact with a lens specific factor. However, general factors may interact with a NF-1 binding site. An overlapping GC and CT box is present in the mouse MIP gene. In the human MIP gene GC and CT boxes are found in different domains of the MIP gene promoter. Both CT boxes interact with factors present in lens nuclear extracts including Sp3. They are able to interact with purified Sp1but not with Sp1 present in mouse lens nuclear extracts. CONCLUSIONS The transcription factor Sp3 may play an important role in regulating MIP gene expression in the lens.
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Affiliation(s)
- S Kim
- Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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260
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Wade PA, Jones PL, Vermaak D, Veenstra GJ, Imhof A, Sera T, Tse C, Ge H, Shi YB, Hansen JC, Wolffe AP. Histone deacetylase directs the dominant silencing of transcription in chromatin: association with MeCP2 and the Mi-2 chromodomain SWI/SNF ATPase. Cold Spring Harb Symp Quant Biol 1999; 63:435-45. [PMID: 10384308 DOI: 10.1101/sqb.1998.63.435] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [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)
- P A Wade
- Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-5431, USA
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261
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Li W, Nagineni CN, Ge H, Efiok B, Chepelinsky AB, Egwuagu CE. Interferon consensus sequence-binding protein is constitutively expressed and differentially regulated in the ocular lens. J Biol Chem 1999; 274:9686-91. [PMID: 10092656 DOI: 10.1074/jbc.274.14.9686] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [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: 11/06/2022] Open
Abstract
Interferon signaling is mediated by STATs and interferon regulatory factor (IRF) families of transcription factors. Ten distinct IRFs have been described and most are expressed in a variety of cells except for interferon consensus sequence-binding protein (ICSBP) and lymphoid-specific IRF/Pip that are thought to be exclusively expressed in lymphoid cells. We show here for the first time that ICSBP is constitutively and inducibly expressed in the mouse lens. In contrast to lymphoid cells with exclusive expression of ICSBP in the nucleus, ICSBP is present in both the cytoplasm and nucleus of the lens cell. However, ICSBP in the nucleus is of lower apparent molecular weight. We further show that the ICSBP promoter is constitutively bound by lens nuclear factors and that its activation requires binding of additional factors including STAT1. Furthermore, transcriptional activation of ICSBP gene by interferon gamma is accompanied by selective nuclear localization of ICSBP in proliferating epithelial cells but not in the nuclei of nondividing cells in the lens fiber compartment. Constitutive and inducible expression of ICSBP in the ocular lens and differential regulation of its subcellular localization in the developing lens suggest that ICSBP may have nonimmunity related functions and that the commonly held view that it is lymphoid-specific be modified.
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Affiliation(s)
- W Li
- Laboratory of Immunology, National Institutes of Health, Bethesda, Maryland 20892, USA
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262
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Abstract
Increasing evidence suggests that pre-mRNA splicing can take place cotranscriptionally in vivo. However, insight into how these two processes are linked has been lacking. Here, we describe that a novel transcriptional coactivator, p52, interacts not only with transcriptional activators and general transcription factors to enhance activated transcription but also with the essential splicing factor ASF/SF2 both in vitro and in vivo to modulate ASF/SF2-mediated pre-mRNA splicing. Furthermore, immunofluorescence studies indicate that the majority of endogenous p52 is colocalized with ASF/SF2 in the nucleoplasm of HeLa cells. Together, these observations suggest that, in addition to functioning as a transcriptional coactivator, p52 may also act as an adaptor to coordinate pre-mRNA splicing and transcriptional activation of class II genes.
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Affiliation(s)
- H Ge
- Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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263
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Ge H, Si Y, Roeder RG. Isolation of cDNAs encoding novel transcription coactivators p52 and p75 reveals an alternate regulatory mechanism of transcriptional activation. EMBO J 1998; 17:6723-9. [PMID: 9822615 PMCID: PMC1171017 DOI: 10.1093/emboj/17.22.6723] [Citation(s) in RCA: 234] [Impact Index Per Article: 9.0] [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: 11/13/2022] Open
Abstract
Transcriptional activation in human cell-free systems containing RNA polymerase II and general initiation factors requires the action of one or more additional coactivators. Here, we report the isolation of cDNAs encoding two novel human transcriptional coactivators (p52 and p75) that are derived from alternatively spliced products of a single gene and share a region of 325 residues, but show distinct coactivator properties. p52 and p75 both show strong interactions with the VP16 activation domain and several components of the general transcriptional machinery. p52, like the previously described PC4, is a potent broad-specificity coactivator, whereas p75 is less active for most activation domains. These results suggest that p52 is a general transcriptional coactivator that mediates functional interactions between upstream sequence-specific activators and the general transcription apparatus, possibly through a novel mechanism.
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Affiliation(s)
- H Ge
- Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
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264
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Martinez E, Ge H, Tao Y, Yuan CX, Palhan V, Roeder RG. Novel cofactors and TFIIA mediate functional core promoter selectivity by the human TAFII150-containing TFIID complex. Mol Cell Biol 1998; 18:6571-83. [PMID: 9774672 PMCID: PMC109242 DOI: 10.1128/mcb.18.11.6571] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [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] [Received: 06/23/1998] [Accepted: 07/31/1998] [Indexed: 12/17/2022] Open
Abstract
TATA-binding protein-associated factors (TAFIIs) within TFIID control differential gene transcription through interactions with both activators and core promoter elements. In particular, TAFII150 contributes to initiator-dependent transcription through an unknown mechanism. Here, we address whether TAFIIs within TFIID are sufficient, in conjunction with highly purified general transcription factors (GTFs), for differential core promoter-dependent transcription by RNA polymerase II and whether additional cofactors are required. We identify the human homologue of Drosophila TAFII150 through cognate cDNA cloning and show that it is a tightly associated component of human TFIID. More importantly, we demonstrate that the human TAFII150-containing TFIID complex is not sufficient, in the context of all purified GTFs and RNA polymerase II, to mediate transcription synergism between TATA and initiator elements and initiator-directed transcription from a TAFII-dependent TATA-less promoter. Therefore, TAFII-promoter interactions are not sufficient for the productive core promoter-selective functions of TFIID. Consistent with this finding, we have partially purified novel cofactor activities (TICs) that potentiate the TAFII-mediated synergism between TATA and initiator elements (TIC-1) and TAFII-dependent transcription from TATA-less promoters (TIC-2 and -3). Furthermore, we demonstrate an essential function for TFIIA in TIC- and TAFII-dependent basal transcription from a TATA-less promoter. Our results reveal a parallel between the basal transcription activity of TAFIIs through core promoter elements and TAFII-dependent activator function.
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Affiliation(s)
- E Martinez
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10021, USA
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265
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Abstract
Previous studies suggest that the polymorphic p53 intron 2 displays a high frequency of mutations, occurring with different frequencies in tumor tissues versus peripheral blood of lung cancer patients as compared to healthy individuals. We evaluated the significance of these polymorphisms and mutations utilizing matched triple specimens from the lung tumor, normal lung tissue, and peripheral blood of cancer patients. Identical genotypes were observed in normal tissues and blood, while 4 mutations were observed in tumors. The A1 allelic frequency was increased in the adenocarcinoma tissues as compared to normal tissues. Two p53 exon 2 polymorphisms were detected, appearing with equal frequencies among cancer patients and healthy individuals. The p53 intron 2 polymorphic locus is a hot spot for mutations in Hong Kong lung cancer patients.
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Affiliation(s)
- H Ge
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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266
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Abstract
Molecular dissection of the B-cell-specific transcription coactivator OCA-B has revealed distinct regions important, respectively, for recruitment to immunoglobulin promoters through interaction with octamer-bound Oct-1 and for subsequent coactivator function. Further analysis of general coactivator requirements showed that selective removal of PC4 from the essential USA fraction severely impairs Oct-1 and OCA-B function in a cell-free system reconstituted with partially purified factors. Full activity can be restored by the combined action of recombinant PC4 and the PC4-depleted USA fraction, thus suggesting a joint requirement for PC4 and another, USA-derived component(s) for optimal function of Oct-1/OCA-B in the reconstituted system. Indeed, USA-derived PC2 was found to act synergistically with PC4 in reproducing the function of intact USA in the assay system. Consistent with the requirement for PC4 in the reconstituted system, OCA-B was found to interact directly with PC4. Surprisingly, however, removal of PC4 from the unfractionated nuclear extract has no detrimental effect on OCA-B/Oct-1-dependent transcription. These results lead to a general model for the synergistic function of activation domains in Oct-1 and OCA-B (mediated by the combined action of the multiple USA components) and, further, suggest a functional redundancy in general coactivators.
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Affiliation(s)
- Y Luo
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10021-6399, USA
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267
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Ohtaka-Maruyama C, Wang X, Ge H, Chepelinsky AB. Overlapping Sp1 and AP2 binding sites in a promoter element of the lens-specific MIP gene. Nucleic Acids Res 1998; 26:407-14. [PMID: 9421492 PMCID: PMC147274 DOI: 10.1093/nar/26.2.407] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [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: 02/05/2023] Open
Abstract
The MIP gene, the founder of the MIP family of channel proteins, is specifically expressed in fiber cells of the ocular lens and expression is regulated temporally and spatially during development. We previously found that a DNA fragment containing 253 bp of 5'-flanking sequence and 42 bp of exon 1 of the human MIP gene contains regulatory elements responsible for lens-specific expression of the MIP gene. In this report we have analyzed the function of overlapping Sp1 and AP2 binding sites present in the MIP promoter. Using DNase I footprinting analysis we found that purified Sp1 and AP2 transcription factors interact with several domains of the human MIP promoter sequence -253/+42. Furthermore, addition of purified Sp1 to Drosophila nuclear extracts activates in vitro transcription from the MIP promoter -253/+42. This promoter activity is competed by oligonucleotides containing domains footprinted with Sp1. Using promoter-reporter gene ( CAT ) constructs we found that the sequence -39/-70 contains a cis regulatory element essential for promoter activity in transient assays in lens cells. EMSA analysis showed that lens nuclear extracts contain factors that bind to the MIP 5'-flanking sequence containing overlapping Sp1 and AP2 binding domains at positions -37/-65. Supershift experiments with lens nuclear extracts indicated that Sp3 is also able to interact with this regulatory element, suggesting that Sp1 and Sp3 may be involved in regulation of transcription of the MIP gene in the lens.
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Affiliation(s)
- C Ohtaka-Maruyama
- Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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268
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Bird SM, Ge H, Uden PC, Tyson JF, Block E, Denoyer E. High-performance liquid chromatography of selenoamino acids and organo selenium compounds. Speciation by inductively coupled plasma mass spectrometry. J Chromatogr A 1997; 789:349-59. [PMID: 9440291 DOI: 10.1016/s0021-9673(97)00657-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.5] [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: 02/05/2023]
Abstract
As part of an ongoing study to identify selenium compounds with cancer chemopreventive activity, extracts of selenium-enriched samples were analyzed by HPLC-inductively coupled plasma (ICP)-MS. Ion-exchange, ion pair and derivatization methods for reversed-phase HPLC were considered and advantages and disadvantages for each compared. Anion exchange allows separation of selenite and selenate, but otherwise provides poor separation. Pre-column derivatization and reversed-phase chromatography provides separation of compounds with terminal amine functionalities, but many other species elute in the void volume. The ion pair method gave optimal separation and was compatible with standard ICP-MS operating conditions.
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Affiliation(s)
- S M Bird
- Department of Chemistry, Lederle Graduate Research Tower A, University of Massachusetts, Amherst 01003-4510, USA
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269
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Abstract
The acetylation of histones increases the accessibility of nucleosomal DNA to transcription factors [1,2], relieving transcriptional repression [3] and correlating with the potential for transcriptional activity in vivo [4 - 7]. The characterization of several novel histone acetyltransferases - including the human GCN5 homolog PCAF (p300/CBP-associated factor) [8], the transcription coactivator p300/CBP [9], and TAFII250 [10] - has provided a potential explanation for the relationship between histone acetylation and transcriptional activation. In addition to histones, however, other components of the basal transcription machinery might be acetylated by these enzymes and directly affect transcription. Here, we examine the acetylation of the basal transcriptional machinery for RNA polymerase II by PCAF, p300 and TAFII250. We find that all three acetyltransferases can direct the acetylation of TFIIEbetaand TFIIF, and we identify a preferred site of acetylation in TFIIEbeta. Human TFIIE consists of two subunits, alpha(p56) and beta(p34), which form a heterotetramer (alpha2 beta2) in solution ([11], reviewed in [12]). TFIIE enters the preinitiation complex after RNA polymerase II and TFIIF, suggesting that TFIIE may interact directly with RNA polymerase II and/or TFIIF [13,14]. In addition, TFIIE can facilitate promoter melting either in the presence or absence of TFIIH and can stimulate TFIIH-dependent phosphorylation of the carboxy-terminal domain of RNA polymerase II [15-18]. TFIIF has an essential role in both transcription initiation and elongation ([19,20], for review see [21]). We discuss the implications of the acetylation of TFIIEbetaand TFIIF for transcriptional control by PCAF, p300 and TAFII250.
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Affiliation(s)
- A Imhof
- Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-5431, USA
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270
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Abstract
The genotypes of L-myc and GSTM1 genes were studied in normal lung tissues of 98 non-small cell lung carcinoma (NSCLC) patients from Hong Kong using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) techniques. Results showed a statistical difference in L-myc genotypes between Chinese and African Americans (P = 0.02). A significant deficit in heterozygotes resulting in the departure from Hardy-Weinberg equilibrium in lung cancer female patients was detected (0.01 < P < 0.02). There were significant differences in survival times in patients having L-L and S-S genotypes, with shorter survival times in the patients with L-L genotypes (0.01 < P < 0.05). Data on age, size of tumor, histological types, and lymph node metastasis showed no significant association with L-myc genotype. The survival time in the GSTM1-negative (null gene) group was significantly different from the GSTM1 positive group between 16 and 24 months after operation (0.01 < P < 0.05). There was no significant difference in the distribution of GSTM1 genotypes between Chinese and Caucasian Americans.
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Affiliation(s)
- H Ge
- Department of Biology, Hong Kong University of Science and Technology, Kowloon, Hong Kong
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271
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Pan ZQ, Ge H, Amin AA, Hurwitz J. Transcription-positive cofactor 4 forms complexes with HSSB (RPA) on single-stranded DNA and influences HSSB-dependent enzymatic synthesis of simian virus 40 DNA. J Biol Chem 1996; 271:22111-6. [PMID: 8703021 DOI: 10.1074/jbc.271.36.22111] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [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: 02/01/2023] Open
Abstract
The replication of simian virus 40 (SV40) DNA in vitro requires a trimeric single-stranded DNA (ssDNA)-binding protein called HSSB or RPA. HSSB supports the unwinding of DNA containing the SV40 origin in the presence of the viral-encoded T antigen and is required for the initiation of RNA primer synthesis as well as processive elongation of DNA catalyzed by the DNA polymerase delta holoenzyme. In this report we show that the transcription positive cofactor 4 (PC4), a ssDNA-binding protein, forms complexes with HSSB on ssDNA and markedly affects the replication functions of HSSB. PC4 supports T antigen-catalyzed unwinding of SV40 origins in lieu of HSSB but inhibits both RNA primer synthesis and polymerase delta-catalyzed DNA chain elongation reactions. These inhibitory effects can be reversed by the addition of excess HSSB. Depending on the concentration of HSSB, PC4 is capable of either inhibiting or activating SV40 DNA replication measured in both mono- and dipolymerase systems. The possible role of PC4 in the initiation of DNA replication is discussed.
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Affiliation(s)
- Z Q Pan
- Derald H. Ruttenberg Cancer Center, The Mount Sinai Medical Center, New York, New York 10029-6574, USA
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272
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Ge H, Bao Z. [Human melanoma-specific peptide antigens recognized by HLA-A2 restricted tumor-infiltrating lymphocytes]. Zhonghua Yi Xue Za Zhi 1996; 76:658-61. [PMID: 9275546] [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: 02/05/2023]
Abstract
OBJECTIVE HLA-A2-associated peptides were extracted from human melanoma cell lines and used to study human melanoma-specific peptide antigens for HLA-A2-restricted tumor-infiltrating lymphocyte (TIL). METHODS TILS were derived from the peripheral lymph nodes of HLA-A2+ human melanoma patients, HLA-A2 molecules were purified from the melanoma cell lines by immunoaffinity column chromatography of detergent-solubilized cell pellets. Peptides bound to the HLA-A2 molecules were acid eluted and fractionated by reversed phase RP-HPLC. Individual fractions were assessed for their ability to reconstitute melanoma-specific epitopes by adding to the HLA-A2+ Ag-processing mutant cell, T2. RESULTS These TIL lysed HLA-A2+ autologous and allogeneic melanomas, but not the HLA-A2- melanomas. They also did not lyse the HLA-A2+ non-melanoma cell lines. The RP-HPLC separations of reconstituting fractions revealed three peaks (fractions) of reconstitution. CONCLUSION These results showed that peptides derived from three active fractions were related to human melanoma-specific peptide antigens recognized by HLA-A2-restricted TIL.
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Affiliation(s)
- H Ge
- Shanghai Institute of Immunology, Shanghai Second Medical University
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273
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Abstract
Transcriptional regulation by nuclear hormone receptors is thought to involve interactions with putative cofactors that may potentiate receptor function. Here we show that human thyroid hormone receptor alpha purified from HeLa cells grown in the presence of thyroid hormone (T3) is associated with a group of distinct nuclear proteins termed thyroid hormone receptor-associated proteins (TRAPs). In an in vitro system reconstituted with general initiation factors and cofactors (and in the absence of added T3), the "liganded" thyroid hormone receptor (TR)/TRAP complex markedly activates transcription from a promoter template containing T3-response elements. Moreover, whereas the retinoid X receptor is not detected in the TR/TRAP complex, its presence is required for the function of the complex. In contrast, human thyroid hormone receptor alpha purified from cells grown in the absence of T3 lacks the TRAPs and effects only a low level of activation that is dependent on added ligand. These findings demonstrate the ligand-dependent in vivo formation of a transcriptionally active TR-multisubunit protein complex and suggest a role for TRAPs as positive coactivators for gene-specific transcriptional activation.
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Affiliation(s)
- J D Fondell
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, NY 10021, USA
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274
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Reardon JT, Ge H, Gibbs E, Sancar A, Hurwitz J, Pan ZQ. Isolation and characterization of two human transcription factor IIH (TFIIH)-related complexes: ERCC2/CAK and TFIIH. Proc Natl Acad Sci U S A 1996; 93:6482-7. [PMID: 8692841 PMCID: PMC39049 DOI: 10.1073/pnas.93.13.6482] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.6] [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: 02/01/2023] Open
Abstract
Transcription factor IIH (TFIIH) is a multisubunit protein complex essential for both the initiation of RNA polymerase class II (pol II)-catalyzed transcription and nucleotide excision repair of DNA. Recent studies have shown that TFIIH copurifies with the cyclin-dependent kinase (cdk)-activating kinase complex (CAK) that includes cdk7, cyclin H, and p36/MAT1. Here we report the isolation of two TFIIH-related complexes: TFIIH* and ERCC2/CAK. TFIIH* consists of a subset of the TFIIH complex proteins including ERCC3 (XPB), p62, p44, p41, and p34 but is devoid of detectable levels of ERCC2 (XPD) and CAK. ERCC2/CAK was isolated as a complex that exhibits CAK activity that cosediments with the three CAK components (cdk7, cyclin H, and p36/MAT1) as well as the ERCC2 (XPD) protein. TFIIH* can support pol II-catalyzed transcription in vitro with lower efficiency compared with TFIIH. This TFIIH*-dependent transcription reaction was stimulated by ERCC2/CAK. The ERCC2/CAK and TFIIH* complexes are each active in DNA repair as shown by their ability to complement extracts prepared from ERCC2 (XPD)- and ERCC3 (XPB)-deficient cells, respectively, in supporting the excision of DNA containing a cholesterol lesion. These data suggest that TFIIH* and ERCC2/CAK interact to form the TFIIH holoenzyme capable of efficiently assembling the pol II transcription initiation complex and directly participating in excision repair reactions.
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Affiliation(s)
- J T Reardon
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill 27599, USA
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275
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Abstract
A polymorphism in intron 2 of the p53 gene, which gives rise to 2 alleles, A1 and A2, was analyzed by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and direct DNA-sequencing techniques. The distribution of this allele in the peripheral blood in the Chinese population comprising 27 healthy individuals, 30 bronchiectasis patients, 34 non-small-cell lung cancer (NSCLC) patients and 27 SCLC patients was analyzed. The genotypic distributions for this marker were significantly different between the blood of healthy individuals and SCLC patients. There was no significant difference between genotypes of Caucasians and Chinese. Tumors, normal lungs and peripheral blood of 83 adenocarcinoma and 10 squamous cell carcinoma patients were also studied. There was a significant difference in the distribution of the genotypes detected in tumor tissues vs. blood of adenocarcinoma patients. The frequency of detection of the A1/A1 genotype in the tumor tissues was increased in adenocarcinoma patients as compared with the blood of adenocarcinoma patients and was decreased in the blood of SCLC patients as compared with the blood of healthy individuals. Survival rates in Hong Kong adenocarcinoma patients with the A1/A1 genotype were lower than those in patients with A1/A2 and A2/A2 genotypes up to 30 months post-operation. Point mutations were detected at the p53 intron 2 polymorphic locus in NSCLC specimens, with a mutation rate of 15.4% (8/52). All mutations were GC transversions. The significance of this instability in p53 intron 2 remains to be elucidated.
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Affiliation(s)
- H Ge
- Department of Biology, Hong Kong University of Science and Technology, Hong Kong
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276
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Ge H, Martinez E, Chiang CM, Roeder RG. Activator-dependent transcription by mammalian RNA polymerase II: in vitro reconstitution with general transcription factors and cofactors. Methods Enzymol 1996; 274:57-71. [PMID: 8902796 DOI: 10.1016/s0076-6879(96)74008-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- H Ge
- Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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277
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Kim TK, Zhao Y, Ge H, Bernstein R, Roeder RG. TATA-binding protein residues implicated in a functional interplay between negative cofactor NC2 (Dr1) and general factors TFIIA and TFIIB. J Biol Chem 1995; 270:10976-81. [PMID: 7738039 DOI: 10.1074/jbc.270.18.10976] [Citation(s) in RCA: 69] [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: 01/26/2023] Open
Abstract
The TATA-binding protein (TBP) plays a key role in transcription initiation. Several negative cofactors (NC1, NC2, and Dr1) are known to interact with TBP in a manner that prevents productive interactions of transcription factors TFIIA and TFIIB with promoter-bound TBP. To gain insights into the regulatory interplay on the surface of TBP, we have employed mutant forms of TBP to identify amino acid residues important for interactions with the negative regulatory cofactor NC2 and the general factor TFIIB. The results show the involvement of distinct domains of TBP in these interactions. Residues (Lys-133, Lys-145, and Lys-151) in the basic repeat region are important for interactions with NC2, as well as with TFIIA (Buratowski, S., and Zhou, H. (1992) Science 255, 1130-1132; Lee, D. K., DeJong, J., Hashimoto, S., Horikoshi, M., and Roeder, R. G. (1992) Mol. Cell. Biol. 12, 5189-5196), whereas a residue (Leu-189) in the second stirrup-like loop spanning S2' and S3' is required for interaction with TFIIB. In addition, we demonstrate that NC2 is identical to the previously cloned negative cofactor Dr1. The implications of these results for TBP structure and function are discussed.
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Affiliation(s)
- T K Kim
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, New York 10021, USA
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278
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Abstract
Human positive cofactor 4 (PC4) mediates activator-dependent transcription by RNA polymerase II, apparently through interactions with transcriptional activators and the basal transcription machinery. We report here that PC4 function is modulated by in vivo phosphorylation. Protein-protein interaction studies and in vitro transcription assays demonstrate that only the nonphosphorylated form of PC4 is functionally active. Although recombinant PC4 can be phosphorylated by casein kinase II and protein kinase C in vitro, mutational and mass spectrometric analyses suggest that the in vivo hyperphosphorylation of PC4 is mediated mainly by casein kinase II and restricted to an N-terminal serine-rich region. These observations provide one example of a transcriptional cofactor that is negatively regulated by casein kinase II phosphorylation.
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Affiliation(s)
- H Ge
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, NY 10021
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279
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Abstract
Activator-dependent transcription in mammalian cells requires upstream stimulatory activity (USA)-derived cofactors in addition to those present in TFIID. A novel positive cofactor (PC4) purified from the human USA fraction effected a marked enhancement (up to 85-fold) of GAL4-AH-dependent transcription in conjunction with TFIID and other general factors. Isolation of a corresponding cDNA identified PC4 as a 127 residue single-stranded DNA-binding protein with serine-rich regions near the N-terminus. Recombinant PC4 was functionally equivalent to native PC4, and both proteins markedly enhanced activation by diverse activation domains fused to the DNA-binding domain of GAL4. Recombinant PC4 interacted independently both with free or DNA-bound VP16 activation domains and with free or DNA-bound TFIIA-TBP complexes (but not with TBP alone). These results indicate that PC4 is a general coactivator that functions cooperatively with TAFs and mediates functional interactions between upstream activators and the general transcriptional machinery.
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Affiliation(s)
- H Ge
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University
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280
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Stevens S, Ge H, Oelgeschlager T, Brunel F, Shi X, Kim TK, Suzuki Y, Hermida L, Fondell J, Wu SY. 'Drive is from within', say scientists. Nature 1994; 370:315. [PMID: 8047119 DOI: 10.1038/370315b0] [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: 01/28/2023]
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281
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Martinez E, Chiang CM, Ge H, Roeder RG. TATA-binding protein-associated factor(s) in TFIID function through the initiator to direct basal transcription from a TATA-less class II promoter. EMBO J 1994; 13:3115-26. [PMID: 7518774 PMCID: PMC395202 DOI: 10.1002/j.1460-2075.1994.tb06610.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.1] [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: 11/05/2022] Open
Abstract
The RNA polymerase II (Pol II) basal transcription factor TFIID is composed of the TATA box-binding protein (TBP) and several TBP-associated factors (TAFs). TBP is required for Pol II transcription from TATA-containing and TATA-less promoters. TATA-less promoters of mRNA-encoding genes often contain an initiator element at the transcription start site that is sufficient to direct accurate Pol II transcription. Here we address the mechanisms of functional TBP recruitment to the TATA-less initiator-dependent promoter of the mouse terminal deoxynucleotidyl transferase (TdT) gene. We show that the natural TATA-less TdT initiator region is sufficient to promote low levels of specific transcription in vitro and to direct the assembly of a stable preinitiation complex. In contrast to what is observed for several other promoters lacking a consensus TATA element, the TATA-binding activity of TBP is not required for the functional recruitment of TFIID to the natural TATA-less TdT and beta-polymerase promoters. Moreover, a comparison of TBP and highly purified epitope-tagged TFIID reveals that one or several TAFs function independently of distal regulatory elements to mediate initiator-directed (basal) transcription from the natural TATA-less TdT core promoter in crude nuclear extracts. Furthermore, by using a transcription system reconstituted with purified components, we present the first evidence for a basal transcription function of TAFs through the TdT initiator element. Altogether, our results suggest an alternative pathway for TFIID recruitment to initiator-dependent TATA-less class II promoters in which TAF(s) recruit TBP by interacting either directly or indirectly with the initiator region.
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Affiliation(s)
- E Martinez
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, NY 10021
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282
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Ge H, Roeder RG. The high mobility group protein HMG1 can reversibly inhibit class II gene transcription by interaction with the TATA-binding protein. J Biol Chem 1994; 269:17136-40. [PMID: 8006019] [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: 01/28/2023] Open
Abstract
Regulation of transcription by RNA polymerase II in eukaryotic cells requires both basal and accessory factors, which interact through specific protein-DNA or protein-protein interactions. The high mobility group 1 protein (HMG1) was previously demonstrated to be a nonhistone chromatin-associated protein, which selectively recognizes cruciform DNA rather than a specific primary sequence element. During our investigations of proteins that interact with TFIID, we found that purified mammalian HMG1, as well as recombinant human HMG1, can interact with TATA-binding protein (TBP) in the presence of a TATA box-containing oligonucleotide to form a specific HMG1.TBP.promoter complex. This complex prevents TFIIB binding to TBP and consequently blocks formation of the preinitiation complex. In contrast, TFIIA can compete with HMG1 for binding to TBP. In an in vitro transcription assay reconstituted with highly purified or recombinant general factors, HMG1 is able to inhibit transcription by RNA polymerase II over 30-fold. As expected, addition of TFIIA can partially reverse this repression in a concentration-dependent manner. These results demonstrate that HMG1, a chromatin-associated protein, has the potential to act as a TBP-dependent negative transcription factor and may provide an important link between chromatin structure and the modulation of class II gene transcription.
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Affiliation(s)
- H Ge
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, New York 10021
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283
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Chiang CM, Ge H, Wang Z, Hoffmann A, Roeder RG. Unique TATA-binding protein-containing complexes and cofactors involved in transcription by RNA polymerases II and III. EMBO J 1993; 12:2749-62. [PMID: 7687540 PMCID: PMC413525 DOI: 10.1002/j.1460-2075.1993.tb05936.x] [Citation(s) in RCA: 142] [Impact Index Per Article: 4.6] [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: 11/09/2022] Open
Abstract
Two multisubunit complexes containing the TATA-binding protein (TBP) were isolated from HeLa cells constitutively expressing the FLAG epitope-tagged TBP using antibody affinity and peptide elution methods. One of the complexes (f:TFIID), isolated from the P11 0.85 M KCl fraction, contains at least 13 specific TBP-associated factors (TAFs) and can mediate activator-dependent transcription by RNA polymerase II. Importantly, activator function through the highly purified f:TFIID complex still requires a general cofactor fraction containing upstream factor stimulatory activity (USA). As previously observed with partially purified activator-competent natural TFIID, f:TFIID generates extended TATA-dependent footprints on the intrinsically strong adenovirus major late promoter (MLP) but only restricted footprints on the weak adenovirus E1b and E4 and HIV (core) promoters. Along with previous demonstrations of activator-induced downstream TFIID interactions on the E4 promoter, these results argue for a relationship between downstream interactions and overall promoter strength. Initiator-like sequences appear not to be essential for downstream interactions since they have no effect on downstream MLP interactions when mutated, do not effect downstream interactions on the HIV promoter and are not present on the inducible E4 promoter. The other multisubunit complex (f:TFIIIB), isolated from the P11 0.30 M KCl fraction, contains four specific TAFs and can substitute for one of the fractions (TFIIIB) required for RNA polymerase III (pol III) transcription. Neither f:TFIID nor TBP could substitute for this pol III TBP-containing fraction. This plus the fact that f:TFIIIB failed to generate a footprint on the MLP underscores the importance of TAFs in determining promoter specificity by different RNA polymerases.
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Affiliation(s)
- C M Chiang
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, NY 10021
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284
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Ge H, Gilmore KJ, Ashraf SA, Too CO, Wallace GG. Investigations into the Use of Poly (3-Methylpyrrole-4-Carboxylic Acid) Coated Silica as a Chromatographic Stationary Phase. ACTA ACUST UNITED AC 1993. [DOI: 10.1080/10826079308019569] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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285
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Ge H, Gilmore K, Ashraf A, Too CO, Wallace GG. Separation of Small Molecules in the Presence of Proteins Using Conducting Polymer Stationary Phases. ACTA ACUST UNITED AC 1993. [DOI: 10.1080/10826079308020899] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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286
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Ge H, Ashraf S, Gilmore K, Too C, Wallace G. Incorporation of various counter-ions during electropolymerization of 3-methylpyrrole-4-carboxylic acid. J Electroanal Chem (Lausanne) 1992. [DOI: 10.1016/0022-0728(92)80288-f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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287
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288
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289
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Abstract
We described previously the purification of a human protein, called alternative splicing factor (ASF), that can switch utilization of alternative 5' splice sites in an SV40 early pre-mRNA. We now report the isolation of a cDNA, designated ASF-1, that encodes this protein. ASF-1 consists of 248 amino acid residues, including an 80 residue RNA-binding domain at its N-terminus and a 50 residue C-terminal region that is 80% serine plus arginine. ASF-1 produced in E. coli can activate splicing in vitro and switch 5' splice-site utilization, establishing that the recombinant protein is sufficient to supply these activities. Analysis of additional cDNAs revealed that ASF pre-mRNA can itself be alternatively spliced, surprisingly, by utilization of a shared 5' splice site and two closely spaced 3' splice sites. Use of the upstream site results in a second mRNA (ASF-2) in which translation of the downstream exon occurs extensively in an alternative reading frame distinct from ASF-1.
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Affiliation(s)
- H Ge
- Department of Biological Sciences, Columbia University, New York, New York 10027
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290
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Abstract
SV40 early pre-mRNA is alternatively spliced by utilization of two different 5' splice sites and a shared 3' splice site to produce large T and small t mRNAs. The ratio of small t to large T mRNAs produced in human embryonic kidney 293 cells is 10- to 20-fold greater than in other mammalian cells, suggesting the existence of a 293 cell-specific factor that modulates alternative splicing. Here we show that nuclear extracts from 293 cells give rise to significantly more small t splicing than do extracts from HeLa cells. Using an in vitro complementation assay, we have characterized and extensively purified a factor from 293 extracts that brings about striking increases in small t splicing with concomitant decreases in large T splicing. The factor is heat sensitive and micrococcal nuclease resistant, suggesting that it is a protein lacking an accessible RNA component. Purification of the alternative splicing factor indicates that the activity is contained in one of several possibly related polypeptides of 30-35 kd.
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Affiliation(s)
- H Ge
- Department of Biological Sciences, Columbia University, New York, New York 10027
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291
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Ge H, Noble J, Colgan J, Manley JL. Polyoma virus small tumor antigen pre-mRNA splicing requires cooperation between two 3' splice sites. Proc Natl Acad Sci U S A 1990; 87:3338-42. [PMID: 2159146 PMCID: PMC53895 DOI: 10.1073/pnas.87.9.3338] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [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: 12/30/2022] Open
Abstract
We have studied splicing of the polyoma virus early region pre-mRNA in vitro. This RNA is alternatively spliced in vivo to produce mRNA encoding the large, middle-sized (MTAg), and small (StAg) tumor antigens. Our primary interest was to learn how the 48-nucleotide StAg intron is excised, because the length of this intron is significantly less than the apparent minimum established for mammalian introns. Although the products of all three splices are detected in vitro, characterization of the pathway and sequence requirements of StAg splicing suggests that splicing factors interact with the precursor RNA in an unexpected way to catalyze removal of this intron. Specifically, StAg splicing uses either of two lariat branch points, one of which is located only 4 nucleotides from the 3' splice site. Furthermore, the StAg splice absolutely requires that the alternative MTAg 3' splice site, located 14 nucleotides downstream of the StAg 3' splice site, be intact. Insertion mutations that increase or decrease the quality of the MTAg pyrimidine stretch enhance or repress StAg as well as MTAg splicing, and a single-base change in the MTAg AG splice acceptor totally blocks both splices. These results demonstrate the ability of two 3' splice sites to cooperate with each other to bring about removal of a single intron.
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Affiliation(s)
- H Ge
- Department of Biological Sciences, Columbia University, New York, NY 10027
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292
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Pan ZQ, Ge H, Fu XY, Manley JL, Prives C. Oligonucleotide-targeted degradation of U1 and U2 snRNAs reveals differential interactions of simian virus 40 pre-mRNAs with snRNPs. Nucleic Acids Res 1989; 17:6553-68. [PMID: 2550896 PMCID: PMC318349 DOI: 10.1093/nar/17.16.6553] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [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: 01/01/2023] Open
Abstract
We have investigated the roles of U1 and U2 snRNP particles in SV40 pre-mRNA splicing by oligonucleotide-targeted degradation of U1 or U2 snRNAs in Xenopus laevis oocytes. Microinjection of oligonucleotides complementary to regions of U1 or U2 RNAs either in the presence or absence of SV40 DNA resulted in specific cleavage of the corresponding snRNA. Unexpectedly, degradation of U1 or U2 snRNA was far more extensive when the oligonucleotide was injected without, or prior to, introduction of viral DNA. In either co-injected or pre-injected oocytes, these oligonucleotides caused a dramatic reduction in the accumulation of spliced SV40 mRNA expressed from the viral late region, and a commensurate increase in unspliced late RNA. When pre-injected, two different U2 specific oligonucleotides also inhibited the formation of both large and small tumor antigen spliced early mRNAs. However, even when, by pre-injection of a U1 5' end-specific oligonucleotide, greater than 95% degradation of the U1 snRNA 5' ends occurred in oocytes, no reduction in early pre-mRNA splicing was observed. In contrast, the same U1 5' end oligonucleotide, when added to HeLa splicing extracts, substantially inhibited the splicing of SV40 early pre-mRNA, indicating that U1 mRNP is not totally dispensable for early splicing. These findings confirm and extend our earlier observations which suggested that different pre-mRNAs vary in their requirements for snRNPs.
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Affiliation(s)
- Z Q Pan
- Department of Biological Sciences, Columbia University, New York, NY 10027
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293
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Noble JC, Ge H, Chaudhuri M, Manley JL. Factor interactions with the simian virus 40 early pre-mRNA influence branch site selection and alternative splicing. Mol Cell Biol 1989; 9:2007-17. [PMID: 2546057 PMCID: PMC362993 DOI: 10.1128/mcb.9.5.2007-2017.1989] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [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: 01/01/2023] Open
Abstract
To study the interaction of splicing factors with the simian virus 40 early-region pre-RNA, which can be alternatively spliced to produce large T and small t mRNAs, we used an in vitro RNase protection assay that defines the 5' boundaries of factor-RNA interactions. Protection products reflecting factor interactions with the large T and small t 5' splice sites and with the multiple lariat branch site region were characterized. All protection products were detected very early in the splicing reaction, before the appearance of spliced RNAs. However, protection of the large T 5' splice site was detected well before small t 5' splice site and branch site protection products, which appeared simultaneously. Oligonucleotide-targeted degradation of small nuclear RNAs (snRNAs) revealed that protection of the branch site region, which occurred at multiple sites, required intact U2 snRNA and was enhanced by U1 snRNA, while protection of the large T and small t 5' splice sites required both U1 and U2 snRNAs. Analysis of several pre-RNAs containing mutations in the branch site region suggests that factor interactions involving the multiple copies of the branch site consensus determine the selection of branch points, which is an important factor in the selection of alternative splicing pathways.
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Affiliation(s)
- J C Noble
- Department of Biological Sciences, Columbia University, New York, New York 10027
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294
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Abstract
We have studied the role in pre-mRNA splicing of the nucleotide sequence preceding the SV40 early region 3' splice site. Somewhat surprisingly, neither the pyrimidine at the highly conserved -3 position, nor the polypyrimidine stretch that extends from -5 to -15, relative to the 3' splice site, were found to be required for efficient splicing. Mutations that delete this region or create polypurine insertions at position -2 had no significant effects on the efficiency of SV40 early pre-mRNA splicing in vivo or in vitro. Interestingly, however, the pyrimidine content of this region had substantial effects on the alternative splicing pattern of this pre-mRNA in vivo. Mutations that increased the number of pyrimidine residues resulted in more efficient utilization of the large T antigen mRNA 5' splice site relative to the small t 5' splice site, while mutations that increased the purine content enhanced small t mRNA splicing. A possible molecular mechanism for these findings, as well as a model that proposes a role for the polypyrimidine stretch in alternative splicing, are discussed.
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Affiliation(s)
- X Y Fu
- Department of Biological Sciences, Columbia University, New York, NY 10027
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295
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DeVries JW, Ge H, Ebert FJ, Magnuson JM, Ogawa MK. Analysis for total sulfite in foods by using rapid distillation followed by redox titration. J Assoc Off Anal Chem 1986; 69:827-30. [PMID: 3771455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A rapid and accurate analysis for total sulfite as sulfur dioxide has been developed for foods and food products. The method, which combines a selective distillation cleanup procedure with the selective redox titration of sulfite ion by iodine, has been applied to a variety of foods and food products over a period of time with no significant interference encountered in any matrixes other than garlic and leeks. For the foods analyzed, the method typically shows a detection limit of 10 ppm, a relative standard deviation of 7.5% (compared with 10.4% for similar matrixes by the Monier-Williams method), and recoveries of 97.9 +/- 6.4%. Comparison of results for this method with those obtained using the Monier-Williams method showed a mean value for the distillation/titration method of 241 ppm compared with 242 ppm for the Monier-Williams method. A correlation of 0.991 and odds of a difference between methods of 10.7% (Student's paired t-test (1-alpha) X 100) were obtained for those matrixes where no interferences were encountered with either method.
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296
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Ge H, Oman GN, Ebert FJ. On-line generation of cyanogen chloride in semiautomated determination of niacin and niacinamide in food products. J Assoc Off Anal Chem 1986; 69:560-2. [PMID: 2941409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The current AOAC procedure for semiautomated determination of niacin specifies the use of externally generated cyanogen bromide. Because of the safety concerns in handling this material, we investigated the use of an alternative system of generating cyanogen chloride in situ, using chloramine-T and potassium cyanide. Recovery studies conducted on 9 different food products yielded average recoveries of 101%. A repeatability study resulted in a measured coefficient of variation of 2.9%. The AOAC niacin method was compared with this semiautomated method; 115 paired analyses on 8 different food types over 6 separate analytical replications indicated no significant difference by a paired t-test at the 95% confidence level.
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297
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Ge H. [Serum concentration of digoxin in patients with congestive heart failure after intravenous furosemide]. Zhonghua Xin Xue Guan Bing Za Zhi 1984; 12:255-6. [PMID: 6544206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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298
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DeVries JW, Defibaugh PW, Dunmire D, Ebert F, Ge H, Oman G, Lim N, Moffitt RA, Muelle EE, Schnitzer R, Shaffer S. Semiautomated Fluorometric Method for Determination of Vitamin C in Foods: Collaborative Study. J AOAC Int 1983. [DOI: 10.1093/jaoac/66.6.1371] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Continuous flow automation of the microfluorometric procedure compares favorably with the manual method in sensitivity, specificity, and generality, and reduces the cost of routine vitamin C assay. Fifteen samples of 12 different products of ready-to-eat cereals, fruit juices, and infant formula were sent to 6 collaborators; one sample in each category was sent as blind duplicates. The within-laboratory standard deviations for 5 collaborators on the 3 sets of blind duplicates were 1.23, 0.87, and 3.64 mg/100 g, respectively. Overall, the average relative standard deviation between laboratories was 11.1% (range 4.5-16.6%) for the manual method and 4.99% (range 1.5-12.6%) for the semiautomated method. The method has been adopted official first action.
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