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Ruas JL, Poellinger L, Pereira T. Role of CBP in regulating HIF-1-mediated activation of transcription. J Cell Sci 2004; 118:301-11. [PMID: 15615775 DOI: 10.1242/jcs.01617] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The hypoxia-inducible factor-1 (HIF-1) is a key regulator of oxygen homeostasis in the cell. We have previously shown that HIF-1alpha and the transcriptional coactivator CBP colocalize in accumulation foci within the nucleus of hypoxic cells. In our further exploration of the hypoxia-dependent regulation of HIF-1alpha function by transcriptional coactivators we observed that coexpression of SRC-1 (another important coactivator of the hypoxia response) and HIF-1alpha did not change the individual characteristic nuclear distribution patterns. Colocalization of both these proteins proved to be mediated by CBP. Biochemical assays showed that depletion of CBP from cell extracts abrogated interaction between SRC-1 and HIF-1alpha. Thus, in contrast to the current model for the assembly of complexes between nuclear hormone receptors and coactivators, the present data suggest that it is CBP that recruits SRC-1 to HIF-1alpha in hypoxic cells. We also observed that CBP, HIF-1alpha/Arnt and HIF-1alpha/CBP accumulation foci partially overlap with the hyperphosphorylated form of RNA polymerase II, and that CBP had a stabilizing effect on the formation of the complex between HIF-1alpha and its DNA-binding partner, Arnt. In conclusion, CBP plays an important role as a mediator of HIF-1alpha/Arnt/CBP/SRC-1 complex formation, coordinating the temporally and hierarchically regulated intranuclear traffic of HIF-1alpha and associated cofactors in signal transduction in hypoxic cells.
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Affiliation(s)
- Jorge L Ruas
- Department of Cell and Molecular Biology, Karolinska Institute, 171 77 Stockholm, Sweden
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2
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Albert AL, Lavoie SB, Vincent M. Multisite phosphorylation of Pin1-associated mitotic phosphoproteins revealed by monoclonal antibodies MPM-2 and CC-3. BMC Cell Biol 2004; 5:22. [PMID: 15171797 PMCID: PMC420459 DOI: 10.1186/1471-2121-5-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2003] [Accepted: 06/01/2004] [Indexed: 12/31/2022] Open
Abstract
Background The peptidyl-prolyl isomerase Pin1 recently revealed itself as a new player in the regulation of protein function by phosphorylation. Pin1 isomerizes the peptide bond of specific phosphorylated serine or threonine residues preceding proline in several proteins involved in various cellular events including mitosis, transcription, differentiation and DNA damage response. Many Pin1 substrates are antigens of the phosphodependent monoclonal antibody MPM-2, which reacts with a subset of proteins phosphorylated at the G2/M transition. Results As MPM-2 is not a general marker of mitotic phosphoproteins, and as most mitotic substrates are phosphorylated more than once, we used a different phosphodependent antibody, mAb CC-3, to identify additional mitotic phosphoproteins and eventual Pin1 substrates by combining affinity purification, MALDI-TOF mass spectrometry and immunoblotting. Most CC-3-reactive phosphoproteins appeared to be known or novel MPM-2 antigens and included the RNA-binding protein p54nrb/nmt55, the spliceosomal protein SAP155, the Ki-67 antigen, MAP-1B, DNA topoisomerases II α and β, the elongation factor hSpt5 and the largest subunit of RNA polymerase II. The CC-3 mitotic antigens were also shown to be Pin1 targets. The fine CC-3- and MPM-2-epitope mapping of the RNA polymerase II carboxy-terminal domain confirmed that the epitopes were different and could be generated in vitro by distinct kinases. Finally, the post-mitotic dephosphorylation of both CC-3 and MPM-2 antigens was prevented when cellular Pin1 activity was blocked by the selective inhibitor juglone. Conclusion These observations indicate that the mitotic phosphoproteins associated with Pin1 are phosphorylated on multiple sites, suggesting combinatorial regulation of substrate recognition and isomerization.
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Affiliation(s)
- Alexandra L Albert
- CREFSIP et Département de médecine, Pavillon Charles-Eugène-Marchand, Université Laval, Québec, Qc, Canada, G1K 7P4
| | - Sébastien B Lavoie
- CREFSIP et Département de médecine, Pavillon Charles-Eugène-Marchand, Université Laval, Québec, Qc, Canada, G1K 7P4
| | - Michel Vincent
- CREFSIP et Département de médecine, Pavillon Charles-Eugène-Marchand, Université Laval, Québec, Qc, Canada, G1K 7P4
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Lavoie SB, Albert AL, Thibodeau A, Vincent M. Heat shock-induced alterations in phosphorylation of the largest subunit of RNA polymerase II as revealed by monoclonal antibodies CC-3 and MPM-2. Biochem Cell Biol 1999. [DOI: 10.1139/o99-037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The phosphorylation of the carboxy-terminal domain of the largest subunit of RNA polymerase II plays an important role in the regulation of transcriptional activity and is also implicated in pre-mRNA processing. Different stresses, such as a heat shock, induce a marked alteration in the phosphorylation of this domain. The expression of stress genes by RNA polymerase II, to the detriment of other genes, could be attributable to such modifications of the phosphorylation sites. Using two phosphodependent antibodies recognizing distinct hyperphosphorylated forms of RNA polymerase II largest subunit, we studied the phosphorylation state of the subunit in different species after heat shocks of varying intensities. One of these antibodies, CC-3, preferentially recognizes the carboxy-terminal domain of the largest subunit under normal conditions, but its reactivity is diminished during stress. In contrast, the other antibody used, MPM-2, demonstrated a strong reactivity after a heat shock in most species studied. Therefore, CC-3 and MPM-2 antibodies discriminate between phosphoisomers that may be functionally different. Our results further indicate that the pattern of phosphorylation of RNA polymerase II in most species varies in response to environmental stress.Key words: RNA polymerase II, heat shock, phosphorylation, CC-3, MPM-2.
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Albert A, Lavoie S, Vincent M. A hyperphosphorylated form of RNA polymerase II is the major interphase antigen of the phosphoprotein antibody MPM-2 and interacts with the peptidyl-prolyl isomerase Pin1. J Cell Sci 1999; 112 ( Pt 15):2493-500. [PMID: 10393805 DOI: 10.1242/jcs.112.15.2493] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The monoclonal antibody MPM-2 recognizes a subset of M phase phosphoproteins in a phosphorylation-dependent manner. It is believed that phosphorylation at MPM-2 antigenic sites could regulate mitotic events since most of the MPM-2 antigens identified to date have M phase functions. In addition, many of these proteins are substrates of the mitotic regulator Pin1, a peptidyl-prolyl isomerase which is present throughout the cell cycle and which is thought to alter its mitotic targets by changing their conformation. In interphase cells, most MPM-2 reactivity is confined to nuclear speckles. We report here that a hyperphosphorylated form of the RNA polymerase II largest subunit is the major MPM-2 interphase antigen. These findings were made possible by the availability of another monoclonal antibody, CC-3, that was previously used to identify a 255 kDa nuclear matrix protein associated with spliceosomal components as a hyperphosphorylated form of the RNA polymerase II largest subunit. MPM-2 recognizes a phosphoepitope of the large subunit that becomes hyperphosphorylated upon heat shock in contrast to the phosphoepitope defined by CC-3, whose reactivity is diminished by the heat treatment. Therefore, these two antibodies may discriminate between distinct functional forms of RNA polymerase II. We also show that RNA polymerase II large subunit interacts with Pin1 in HeLa cells. Pin1 may thus regulate transcriptional and post-transcriptional events by catalyzing phosphorylation-dependent conformational changes of the large RNA polymerase II subunit.
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Affiliation(s)
- A Albert
- Département de médecine and CREFSIP, Pavillon C.-E.-Marchand, Université Laval, Ste-Foy, Québec, Canada, G1K 7P4
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LeBlanc MH, Boudriau S, Doyle D, Gagnon A, Beaudoin D, Coulombe D, Gleeton O, Kingma JG, Boutet M. Epstein-Barr virus mediated graft rejection in heart transplant patients: implication of the cardiac cytoskeleton. Transplant Proc 1998; 30:918-24. [PMID: 9595146 DOI: 10.1016/s0041-1345(98)00096-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Reyes JC, Muchardt C, Yaniv M. Components of the human SWI/SNF complex are enriched in active chromatin and are associated with the nuclear matrix. J Cell Biol 1997; 137:263-74. [PMID: 9128241 PMCID: PMC2139781 DOI: 10.1083/jcb.137.2.263] [Citation(s) in RCA: 183] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/1996] [Revised: 02/06/1997] [Indexed: 02/04/2023] Open
Abstract
Biochemical and genetic evidence suggest that the SWI/SNF complex is involved in the remodeling of chromatin during gene activation. We have used antibodies specific against three human subunits of this complex to study its subnuclear localization, as well as its potential association with active chromatin and the nuclear skeleton. Immunofluorescence studies revealed a punctate nuclear labeling pattern that was excluded from the nucleoli and from regions of condensed chromatin. Dual labeling failed to reveal significant colocalization of BRG1 or hBRM proteins with RNA polymerase II or with nuclear speckles involved in splicing. Chromatin fractionation experiments showed that both soluble and insoluble active chromatin are enriched in the hSWI/SNF proteins as compared with bulk chromatin. hSWI/SNF proteins were also found to be associated with the nuclear matrix or nuclear scaffold, suggesting that a fraction of the hSWI/SNF complex could be involved in the chromatin organization properties associated with matrix attachment regions.
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Affiliation(s)
- J C Reyes
- Unité des Virus Oncogènes, UA1644 du Centre National de la Recherche Scientifique, Département des Biotechnologies, Institut Pasteur, Paris, France
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Vincent M, Lauriault P, Dubois MF, Lavoie S, Bensaude O, Chabot B. The nuclear matrix protein p255 is a highly phosphorylated form of RNA polymerase II largest subunit which associates with spliceosomes. Nucleic Acids Res 1996; 24:4649-52. [PMID: 8972849 PMCID: PMC146315 DOI: 10.1093/nar/24.23.4649] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The monoclonal antibody CC-3 recognizes a phosphodependent epitope on a 255 kDa nuclear matrix protein (p255) recently shown to associate with splicing complexes as part of the [U4/U6.U5] tri-snRNP particle [Chabot et al. (1995) Nucleic Acids Res. 23, 3206-3213]. In mouse and Drosophila cultured cells the electrophoretic mobility of p255, faster in the latter species, was identical to that of the hyperphosphorylated form of RNA polymerase II largest subunit (IIo). The CC-3 immunoreactivity of p255 was abolished by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole, which is known to cause the dephosphorylation of the C-terminal domain of subunit IIo by inhibiting the TFIIH-associated kinase. The identity of p255 was confirmed by showing that CC-3-immunoprecipitated p255 was recognized by POL3/3 and 8WG16, two antibodies specific to RNA polymerase II largest subunit. Lastly, the recovery of RNA polymerase II largest subunit from HeLa splicing mixtures was compromised by EDTA, which prevents the interaction of p255 with splicing complexes and inhibits splicing. Our results indicate that p255 represents a highly phosphorylated form of RNA polymerase II largest subunit physically associated with spliceosomes and possibly involved in coupling transcription to RNA processing.
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Affiliation(s)
- M Vincent
- Département de Médecine, Recherche en Sciences de la Vie et de la Santé, Université Laval, Ste-Foy, Québec, Canada.
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Chabot B, Bisotto S, Vincent M. The nuclear matrix phosphoprotein p255 associates with splicing complexes as part of the [U4/U6.U5] tri-snRNP particle. Nucleic Acids Res 1995; 23:3206-13. [PMID: 7667097 PMCID: PMC307179 DOI: 10.1093/nar/23.16.3206] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The monoclonal antibody CC3 recognizes a phosphorylated epitope present on an interphase protein of 255 kDa. Previous work has shown that p255 is localized mainly to nuclear speckles and remains associated with the nuclear matrix scaffold following extraction with non-ionic detergents, nucleases and high salt. The association of p255 with splicing complexes is suggested by the finding that mAb CC3 can inhibit in vitro splicing and immunoprecipitate pre-messenger RNA and splicing products. Small nuclear RNA immunoprecipitation assays show that p255 is a component of the U5 small nuclear ribonucleoprotein (snRNP) and the [U4/U6.U5] tri-snRNP complex. In RNase protection assays, mAb CC3 immunoprecipitates fragments containing branch site and 3' splice site sequences. As predicted for a [U4/U6.U5]-associated component, the recovery of the branch site-protected fragment requires binding of U2 snRNP and is inhibited by EDTA. p255 may correspond to the previously identified p220 protein, the mammalian analogue of the yeast PRP8 protein. Our results suggest that changes in the phosphorylation of p255 may be part of control mechanisms that interface splicing activity with nuclear organization.
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Affiliation(s)
- B Chabot
- Département de Microbiologie, Faculté de Médecine, Université de Sherbrooke, Québec, Canada
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Bisotto S, Lauriault P, Duval M, Vincent M. Colocalization of a high molecular mass phosphoprotein of the nuclear matrix (p255) with spliceosomes. J Cell Sci 1995; 108 ( Pt 5):1873-82. [PMID: 7657711 DOI: 10.1242/jcs.108.5.1873] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It was previously demonstrated that monoclonal antibody CC-3 binds to a phosphorylation dependent epitope present on a 255 kDa nuclear protein (p255). We show here that in interphase cells, p255 distributes to typical nuclear speckles that correspond to the localization of spliceosome components as revealed by antibodies to the m3G cap of snRNAs or to the non-snRNP splicing factor SC-35. Immunofluorescence and immunoblot studies indicated that p255 is resistant to extraction with non-ionic detergents, nucleases and high ionic strength buffers and may thus be defined biochemically as a nuclear matrix phosphoprotein. To determine the nature of the association of p255 with the nuclear structure, its distribution was studied at different stages of the cell cycle and after the cells were treated with nucleases or heat shocked. We found that the antigen diffused into the cytoplasm during metaphase but was reorganized into cytoplasmic speckles during anaphase-telophase transition, where it colocalized with SC-35. Nuclear matrix preparations that were digested with DNases and RNases showed that interphasic p255 still localized to nuclear speckles even though snRNA and snRNP antigens were removed. Heat-shocked cells labelled with monoclonal antibody CC-3 exhibited more rounded and less interconnected speckles, identical to those decorated by anti-SC-35 antibody under such conditions. These results indicate that p255 and SC-35 are present in the same nuclear structures, to which they are more tightly bound than the snRNP antigens. They further suggest that both proteins are implicated in spliceosome assembly or attachment.
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Affiliation(s)
- S Bisotto
- CHUL Research Center, Laval University, Ste-Foy, Québec, Canada
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Thibodeau A, Vincent M. Monoclonal antibody CC-3 recognizes phosphoproteins in interphase and mitotic cells. Exp Cell Res 1991; 195:145-53. [PMID: 2055264 DOI: 10.1016/0014-4827(91)90510-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Among a library of monoclonal antibodies (mAbs) recognizing developmental markers in the chick embryo, mAb CC-3 was selected because of its differential immunostaining of mitotic cells. The intracellular distribution of the CC-3 antigen (CC-3a) throughout the cell cycle was visualized by immunolocalization. In interphase cells CC-3a resided in the nucleus and was arranged in distinct extranucleolar clusters. At prophase, the nuclear reactivity of CC-3a considerably increased and subsequently extended to the cytoplasm at metaphase. From metaphase through anaphase, most of the reactivity was associated with the mitotic apparatus. During cytokinesis CC-3a was detected in the mid-body and also in discrete speckles dispersed throughout the cytoplasm. The initial interphase pattern was then restored in the two daughter nuclei. Immunoblot analysis demonstrated that a 255-kDa phosphoprotein was present only in the interphase nucleus and that a complete new set of phosphoproteins accounted for the mitotic cell reactivity. The binding of CC-3 was dependent on the phosphorylation of its antigens. CC-3a is an evolutionary conserved molecule; it is present in such phylogenetically distant species as Drosophila and humans. Furthermore, the unique behavior of CC-3 on sections of normal, embryonic, and regenerative tissue and in cell culture immunostaining make it a reliable tool to identify mitotic foci.
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Affiliation(s)
- A Thibodeau
- Ontogenèse et Génétique Moléculaire, Centre de recherche du CHUL, Sainte-Foy, Québec, Canada
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Duchaine J, Levasseur S, Vincent M. Expression of a complex developmental antigen in precise morphogenetic processes during chick embryogenesis. Dev Genes Evol 1990; 199:80-88. [PMID: 28305722 DOI: 10.1007/bf02029554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/1990] [Accepted: 05/11/1990] [Indexed: 10/25/2022]
Abstract
In order to identify transitory molecules involved in specific events during development, monoclonal antibodies were raised against various structures of the chick embryo at stages exhibiting important tissue reorganization. A7H2 is a monoclonal antibody reacting with an epitope suddenly expressed in select embryonic tissues during precise morphogenetic processes. Splanchnomesoderm and most mesothelia exhibited a strong immunoreactivity during organogenesis whereas non-mesodermal A7H2-activities were usually confined to invaginating or folding epithelia. Most embryonic reactivities were transient but the amnion demonstrated a strong and persistent reactivity and therefore was selected as a source of material for A7H2-antigen characterization. The antigenic determinant was shown to be on a huge molecular complex having a pI of 5. Immunoblots obtained after SDS-PAGE demonstrated a highly disperse pattern in the high MW region of the gel that could be altered or abolished by proteolytic treatments. Fingerprint analysis of the immunoreactive peptide bands demonstrated a clear relationship between them. Using different fixation and permeabilization procedures on amnion cultured cells, we have observed that A7H2-antigen was associated with the cytoplasmic face of the plasma membrane and was resistant to treatments removing most cellular components and producing substratum-attached ventral membranes. We suggest that this macromolecular complex plays a role in specific subsets of cells involved in precise morphogenetic processes, possibly as a link with the external milieu or as a membrane associated structure.
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Affiliation(s)
- Jean Duchaine
- Ontogénèse et Génétique moléculaires, Centre de Recherche du CHUL, 2705 boul. Laurier, Ste-Foy, GIV 4G2, Québec, Canada.,Département de Médecine, Université Laval, Canada
| | - Sylvain Levasseur
- Ontogénèse et Génétique moléculaires, Centre de Recherche du CHUL, 2705 boul. Laurier, Ste-Foy, GIV 4G2, Québec, Canada.,Département de Médecine, Université Laval, Canada
| | - Michel Vincent
- Ontogénèse et Génétique moléculaires, Centre de Recherche du CHUL, 2705 boul. Laurier, Ste-Foy, GIV 4G2, Québec, Canada.,Département de Médecine, Université Laval, Canada
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