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Cerna D, Wilson DK. The structure of Sif2p, a WD repeat protein functioning in the SET3 corepressor complex. J Mol Biol 2005; 351:923-35. [PMID: 16051270 DOI: 10.1016/j.jmb.2005.06.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Revised: 06/07/2005] [Accepted: 06/09/2005] [Indexed: 11/22/2022]
Abstract
In Saccharomyces cerevisiae, the SIF2 gene product is an integral component of the Set3 complex (SET3C), an assembly of proteins with some homology to the human SMRT and N-CoR corepressor complexes. SET3C has histone deacetylase activity that is responsible for repressing a set of meiotic genes. We have determined the X-ray crystal structure of a 46 kDa C-terminal domain of a SET3C core protein, Sif2p to 1.55 A resolution and a crystallographic R-factor of 19.0%. This domain contains an unusual eight-bladed beta-propeller structure, which differs from other transcriptional corepressor structures such as yeast Tup1p and human groucho (Gro)/TLE1, which have only seven. We have demonstrated intact Sif2p is a tetramer and the N-terminal LisH (Lis-homology)-containing domain mediates tetramerization and interaction with another component of SET3C, Snt1p. Multiple sequence alignments indicate that a surface on the "top" of the protein is conserved among species, suggesting that it may play a common role in binding partner proteins. Since Sif2p appears to be the yeast homolog of human TBL1 and TBLR1, which function in the N-CoR/SMRT complexes, its structural and oligomeric properties are likely to be very similar.
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Affiliation(s)
- David Cerna
- Section of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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Kumar R, Gururaj AE, Vadlamudi RK, Rayala SK. The clinical relevance of steroid hormone receptor corepressors. Clin Cancer Res 2005; 11:2822-31. [PMID: 15837729 DOI: 10.1158/1078-0432.ccr-04-1276] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Steroid hormone receptors are ligand-dependent transcription factors that control a variety of essential physiologic and developmental processes in humans. The functional activity of a steroid receptor is regulated not only by hormones but also by an array of regulatory proteins such as coactivators, corepressors, and chromatin modifiers. Contrary to an earlier notion that corepressors and coactivators exist in separate complexes, these molecules, which have apparently opposite functions, are increasingly being found in the same complex, which allows for efficient transcriptional control mechanisms. These control mechanisms are in turn regulated by an array of post-translational modifications under the influence of upstream and local signaling networks. Because the outcome of steroidal hormone receptor transcriptional complexes is measured in terms of the expression of target genes, any dysregulation of coregulator complexes perturbs normal homeostasis and could contribute to the development and maintenance of malignant phenotypes. Increasing evidence implicating steroid hormone receptors and their coregulators in various pathophysiologic conditions has elicited interest in their structure and biology. Further advances in this field of study should open up a unique window for novel targeted therapies for diseases such as cancer. Here we briefly review the clinical relevance of corepressors, with a particular focus on their role in the development of cancerous phenotypes.
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Affiliation(s)
- Rakesh Kumar
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
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Yan HT, Shinka T, Kinoshita K, Sato Y, Umeno M, Chen G, Tsuji K, Unemi Y, Yang XJ, Iwamoto T, Nakahori Y. Molecular analysis of TBL1Y, a Y-linked homologue of TBL1X related with X-linked late-onset sensorineural deafness. J Hum Genet 2005; 50:175-181. [PMID: 15834507 DOI: 10.1007/s10038-005-0237-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Accepted: 01/22/2005] [Indexed: 11/28/2022]
Abstract
Recent progress in sequencing the human Y chromosome has unveiled a series of X-Y homologous genes. In the present study, we focused on Transducin beta-like 1Y (TBL1Y), which is a Y-linked homologue of TBL1X that is related with X-linked late-onset sensorineural deafness. Recently, it has been shown that TBLR1, another homologue whose gene resides on chromosome 3, and TBL1X act as a corepressor/coactivator exchanger for several nuclear receptors and transcription factors. However, the expression pattern and function of TBL1Y remain unknown. The RT-PCR analysis of the TBL1 family revealed that TBL1Y was expressed in all 13 tissues examined but not in leukocytes. Among the cell lines tested, however, it was only expressed in NT2/D1 cells and in lymphoblasts transformed with Epstein Barr (EB) virus. To compare the functions of the TBL1 family, we generated a series of expression plasmids for GAL4DBD-fused proteins of the TBL1 family. We carried out dual luciferase assays using these plasmids in combination with a plasmid having a luciferase reporter gene harboring 5xGAL4 binding sites. Unlike the other constructs, GAL4DBD-fused TBL1Y did not repress the promoter activity. Moreover, we found three novel polymorphisms in the TBL1Y gene, IVS7+9G>A, G268C, and IVS7+1G>C, which is presumed to cause splicing error. These polymorphisms are found in males within Y-haplogroup O3 (XO3e), which is defined as the Y-haplogroup O3 excluding O3e, a branch of O3. The results show that TBL1Y differs from other members of the TBL1 family in expression and function, suggesting other roles in maleness.
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Affiliation(s)
- Hong-Tao Yan
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
- The Researcher of Graduate School of Medical Sciences for 'Disease Proteomics for Multifactorial Disorder', 21st Century Center for Excellence (COE)Program. , University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Toshikatsu Shinka
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Keigo Kinoshita
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Youichi Sato
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Mayumi Umeno
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Gang Chen
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Keiko Tsuji
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Yukiko Unemi
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Xin-Jun Yang
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Teruaki Iwamoto
- Department of Urology, School of Medicine, St. Marianna Medical University, 2-16-1 Sugao, Miyamae, Kawasaki, 216-8511, Japan
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Yutaka Nakahori
- Department of Human Genetics and Public Health, Faculty of Medicine, Graduate School of Proteomics, The University of Tokushima, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan.
- Core Research for Evolutional Science and Technology Corporation (CREST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
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Craig IW, Mill J, Craig GM, Loat C, Schalkwyk LC. Application of microarrays to the analysis of the inactivation status of human X-linked genes expressed in lymphocytes. Eur J Hum Genet 2004; 12:639-46. [PMID: 15114374 DOI: 10.1038/sj.ejhg.5201212] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Dosage compensation in mammalian females is achieved by the random inactivation of one X chromosome early in development; however, inactivation is not complete. In addition to a majority of pseudoautosomal loci, there are genes that are expressed from both the active and the inactive X chromosomes, and which are interspersed among other genes subject to regular dosage compensation. The patterns of X-linked gene expression in different tissues are of great significance for interpreting their impact on sex differences in development. We have examined the suitability and sensitivity of a microarray approach for determining the inactivation status of X-linked genes. Biotinylated cRNA from six female and six male lymphocyte samples were hybridised to Affymetrix HG-U133A microarrays. A total of 36 X-linked targets detected significantly higher levels of female transcripts, suggesting that these corresponded to sequences from loci that escaped, at least partly, from inactivation. These included genes for which previous experimental evidence, or circumstantial evidence, existed for their escape, and some novel candidates. Six of the targets were represented by more than one probe set, which gave independent support for the conclusions reached.
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Affiliation(s)
- Ian W Craig
- SGDP Centre, Institute of Psychiatry, Box PO 82, Denmark Hill, London SE5, UK.
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55
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Tomita A, Buchholz DR, Shi YB. Recruitment of N-CoR/SMRT-TBLR1 corepressor complex by unliganded thyroid hormone receptor for gene repression during frog development. Mol Cell Biol 2004; 24:3337-46. [PMID: 15060155 PMCID: PMC381683 DOI: 10.1128/mcb.24.8.3337-3346.2004] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The corepressors N-CoR (nuclear receptor corepressor) and SMRT (silencing mediator for retinoid and thyroid hormone receptors) interact with unliganded nuclear hormone receptors, including thyroid hormone (T(3)) receptor (TR). Several N-CoR/SMRT complexes containing histone deacetylases have been purified. The best studied among them are N-CoR/SMRT complexes containing TBL1 (transducin beta-like protein 1) or TBLR1 (TBL1-related protein). Despite extensive studies of these complexes, there has been no direct in vivo evidence for the interaction of TBL1 or TBLR1 with TR or the possible involvement of such complexes in gene repression by any nuclear receptors in any animals. Here, we used the frog oocyte system to demonstrate that unliganded TR interacts with TBLR1 and recruits TBLR1 to its chromatinized target promoter in vivo, accompanied by histone deacetylation and gene repression. We further provide evidence to show that the recruitment of TBLR1 or related proteins is important for repression by unliganded TR. To investigate the potential role for TBLR1 complexes during vertebrate development, we made use of T(3)-dependent amphibian metamorphosis as a model. We found that TBLR1, SMRT, and N-CoR are recruited to T(3)-inducible promoters in premetamorphic tadpoles and are released upon T(3) treatment, which induces metamorphosis. More importantly, we demonstrate that the dissociation of N-CoR/SMRT-TBLR1 complexes from endogenous TR target promoters is correlated with the activation of these genes during spontaneous metamorphosis. Taken together, our studies provide in vivo evidence for targeted recruitment of N-CoR/SMRT-TBLR1 complexes by unliganded TR in transcriptional repression during vertebrate development.
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Affiliation(s)
- Akihiro Tomita
- Section on Molecular Morphogenesis, Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-5431, USA
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56
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Perissi V, Aggarwal A, Glass CK, Rose DW, Rosenfeld MG. A corepressor/coactivator exchange complex required for transcriptional activation by nuclear receptors and other regulated transcription factors. Cell 2004; 116:511-26. [PMID: 14980219 DOI: 10.1016/s0092-8674(04)00133-3] [Citation(s) in RCA: 431] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2003] [Revised: 01/05/2004] [Accepted: 01/06/2004] [Indexed: 01/30/2023]
Abstract
The mechanisms that control the precisely regulated switch from gene repression to gene activation represent a central question in mammalian development. Here, we report that transcriptional activation mediated by liganded nuclear receptors unexpectedly requires the actions of two highly related F box/WD-40-containing factors, TBL1 and TBLR1, initially identified as components of an N-CoR corepressor complex. TBL1/TBLR1 serve as specific adaptors for the recruitment of the ubiquitin conjugating/19S proteasome complex, with TBLR1 selectively serving to mediate a required exchange of the nuclear receptor corepressors, N-CoR and SMRT, for coactivators upon ligand binding. Tbl1 gene deletion in embryonic stem cells severely impairs PPARgamma-induced adipogenic differentiation, indicating that TBL1 function is also biologically indispensable for specific nuclear receptor-mediated gene activation events. The role of TBLR1 and TBL1 in cofactor exchange appears to also operate for c-Jun and NFkappaB and is therefore likely to be prototypic of similar mechanisms for other signal-dependent transcription factors.
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Affiliation(s)
- Valentina Perissi
- Howard Hughes Medical Institute, Department of Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla 92093, USA
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57
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Abstract
Somatic cloning by nuclear transfer returns a differentiated cell to a totipotent stage, a process termed nuclear reprogramming. During this de-differentiation process, genes inactivated during tissue differentiation are re-activated in a temporal and spatial special manner. It is believed that tissue differentiation occurs through epigenetic mechanisms, genetic inheritance that does not involve changes in DNA sequences. Developmental abnormalities and a high mortality rate in cloned offspring have frequently been observed and probably result from incomplete nuclear reprogramming. In this review, the reprogramming of two epigenetic mechanisms, imprinting and X chromosome inactivation, as well as recent attempts to modify pre-existing epigenetic marks in donor cells to improve nuclear transfer efficacy, are discussed.
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Affiliation(s)
- X Cindy Tian
- Centre for Regenerative Biology/Department of Animal Science, University of Connecticut, Storrs, CT 06269-4243, USA.
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58
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van Nocker S, Ludwig P. The WD-repeat protein superfamily in Arabidopsis: conservation and divergence in structure and function. BMC Genomics 2003; 4:50. [PMID: 14672542 PMCID: PMC317288 DOI: 10.1186/1471-2164-4-50] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2003] [Accepted: 12/12/2003] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The WD motif (also known as the Trp-Asp or WD40 motif) is found in a multitude of eukaryotic proteins involved in a variety of cellular processes. Where studied, repeated WD motifs act as a site for protein-protein interaction, and proteins containing WD repeats (WDRs) are known to serve as platforms for the assembly of protein complexes or mediators of transient interplay among other proteins. In the model plant Arabidopsis thaliana, members of this superfamily are increasingly being recognized as key regulators of plant-specific developmental events. RESULTS We analyzed the predicted complement of WDR proteins from Arabidopsis, and compared this to those from budding yeast, fruit fly and human to illustrate both conservation and divergence in structure and function. This analysis identified 237 potential Arabidopsis proteins containing four or more recognizable copies of the motif. These were classified into 143 distinct families, 49 of which contained more than one Arabidopsis member. Approximately 113 of these families or individual proteins showed clear homology with WDR proteins from the other eukaryotes analyzed. Where conservation was found, it often extended across all of these organisms, suggesting that many of these proteins are linked to basic cellular mechanisms. The functional characterization of conserved WDR proteins in Arabidopsis reveals that these proteins help adapt basic mechanisms for plant-specific processes. CONCLUSIONS Our results show that most Arabidopsis WDR proteins are strongly conserved across eukaryotes, including those that have been found to play key roles in plant-specific processes, with diversity in function conferred at least in part by divergence in upstream signaling pathways, downstream regulatory targets and /or structure outside of the WDR regions.
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Affiliation(s)
- Steven van Nocker
- Cell and Molecular Biology Program and Department of Horticulture, 390 Plant and Soil Sciences Building, Michigan State University, East Lansing, MI, 48824, USA
| | - Philip Ludwig
- Cell and Molecular Biology Program and MSU-DOE Plant Research Laboratory, 2240 Biomedical Physical Sciences Building, Michigan State University, East Lansing, MI, 48824, USA
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59
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Lin B, White JT, Utleg AG, Wang S, Ferguson C, True LD, Vessella R, Hood L, Nelson PS. Isolation and characterization of human and mouse WDR19,a novel WD-repeat protein exhibiting androgen-regulated expression in prostate epithelium. Genomics 2003; 82:331-42. [PMID: 12906858 DOI: 10.1016/s0888-7543(03)00151-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Androgens regulate important processes involved in the normal development and function of the human and rodent prostate glands. Here we report the isolation and characterization of a new androgen-regulated gene, designated WDR19, that encodes repeating sequence motifs found in the WD-repeat family of proteins. The WD repeat is a conserved domain of approximately 40 amino acids that is typically bracketed by glycine-histidine and tryptophan-aspartic acid (WD) dipeptides. WD-repeat proteins are a large group of structurally related proteins that participate in a wide range of cellular functions, including transmembrane signaling, mRNA modification, vesicle formation, and vesicular trafficking. The WDR19 gene comprises 36 exons and is located on chromosome 4p15-4p11. The predicted protein contains six WD repeats, a clathrin heavy-chain repeat, and three transmembrane domains. Sequence analysis reveals that the WDR19 gene is conserved from Caenorhabditis elegans to human. WDR19 is expressed in normal and neoplastic prostate epithelium as demonstrated by RNA in situ hybridization and is regulated by androgenic hormones. WDR19 transcripts exhibit alternative splicing in which two isoforms appear to be prostate restricted, a property that could be exploited for designing diagnostic or therapeutic strategies for prostate carcinoma.
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Affiliation(s)
- Biaoyang Lin
- The Institute for Systems Biology, 1441 North 34th Street, Seattle, WA, 98103, USA.
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60
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Jones PL, Shi YB. N-CoR-HDAC corepressor complexes: roles in transcriptional regulation by nuclear hormone receptors. Curr Top Microbiol Immunol 2003; 274:237-68. [PMID: 12596910 DOI: 10.1007/978-3-642-55747-7_9] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Many nuclear hormone receptors (NHRs) actively repress the expression of their primary response genes through the recruitment of transcriptional corepressor complexes to regulated promoters. N-CoR and the highly related SMRT were originally isolated and characterized by their ability to interact exclusivelywith the unliganded forms of NHRs and confer transcriptional repression. Recently, both the N-CoR and SMRT corepressors have been found to exist in vivo in multiple, distinct macromolecular complexes. While these corepressor complexes differ in overall composition, a general theme is that they contain histone deacetylase enzymatic activity. Several of these complexes contain additional transcriptional corepressor proteins with functional ties to chromatin structure. Together, these data suggest that modulation of chromatin structure plays a central role in N-CoR mediated transcriptional repression from unliganded NHRs.
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Affiliation(s)
- P L Jones
- Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, B107 CLSL, 601 S. Goodwin Ave, Urbana, IL 61801, USA.
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61
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Kuncewicz T, Sheta EA, Goldknopf IL, Kone BC. Proteomic analysis of S-nitrosylated proteins in mesangial cells. Mol Cell Proteomics 2003; 2:156-63. [PMID: 12671063 DOI: 10.1074/mcp.m300003-mcp200] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NO participates in numerous biological events in a variety of cell types including activated glomerular mesangial cells. Many of these events appear to be independent of the known effects of NO on soluble guanylyl cyclase. NO derived from all major isoforms of NO synthase can S-nitrosylate cysteine residues in target proteins, potentially altering their functional activities. Recent evidence suggests that S-nitrosylation is specific, is regulated, and may play an important regulatory role akin to phosphorylation. In the present study, the "biotin-switch" method of isolating S-nitrosylated proteins was coupled with two-dimensional PAGE protein separation followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and peptide mass fingerprinting to identify target proteins for S-nitrosylation in murine mesangial cells treated with NO donors or appropriate controls. This approach resolved 790 protein spots. We analyzed the most abundant spots and identified 34 known proteins. Of these, 31 are unique S-nitrosylated proteins not previously identified, including signaling proteins, receptors and membrane proteins, cytoskeletal or cell matrix proteins, and cytoplasmic proteins. Prominent among these were peroxisome proliferator activated receptor gamma, uroguanylin, GTP-binding protein alpha, protein 14-3-3, NADPH-cytochrome P450 oxidoreductase, transcription factor IIA, melusin, mitosin, phospholipase A2-activating protein, and protein-tyrosine phosphatase. The in vivo induction of S-nitrosylation was assayed by treating mesangial cells with interleukin-1beta followed by the biotin-switch and Western blot of selected targets. These results broaden our knowledge of potential signal transduction pathways and other cell functions mediated by NO S-nitrosylation.
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Affiliation(s)
- Teresa Kuncewicz
- Department of Internal Medicine, The University of Texas Medical School at Houston, Houston, Texas 77030, USA
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Hegde M, Lewis RA, Richards CS. Diagnostic DNA testing for X-linked ocular albinism (OA1) with a hierarchical mutation screening protocol. GENETIC TESTING 2002; 6:7-14. [PMID: 12180081 DOI: 10.1089/109065702760093852] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Albinism is a group of inherited conditions in which affected individuals have less than normal pigment in the eyes, skin, and hair compared to others of the same race and ethnic background. The prevalence of all types of albinism in the United States is estimated at 1 in 20,000, based on poor epidemiological data. X-linked Nettleship-Falls ocular albinism (XLOA, OA1) affects approximately 1/150,000 males in the population. XLOA effects reduce visual acuity and nystagmus, result in a mild skin and hair phenotype, and occur mostly in XY males. Female carriers of XLOA have normal visual acuity, but often show iris punctate transillumination and a classic pattern of mosaic retinal pigmentation, coarse and grainy in the macula and becoming increasingly reticular into the periphery of the retinal pigment epithelium. Studies of OA1 have shown linkage of a single gene to markers at Xp22.3-p22.2. About 48% of the reported mutations in the OA1 gene are intragenic deletions and about 43% are point mutations. We present a hierarchical strategy for mutation screening for diagnostic testing for OA1 that comprises two tiers: first, multiplex PCR to detect intragenic deletions in the OA1 gene with denaturing high-performance liquid chromatography (dHPLC), and, second, heteroduplex analysis with dHPLC to scan for mutations, with subsequent sequencing of variants to confirm putative mutations in the OA1 gene. Prenatal diagnosis can be provided for families when the mutation has been firmly identified. We have validated this procedure with positive controls that were identified in patients by Southern blot, single-stranded conformation polymorphism (SSCP), and sequencing. In this hierarchical strategy, these procedures have an analytical sensitivity of > 99%.
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Affiliation(s)
- M Hegde
- Diagnostic Sequencing Laboratory, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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63
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Stöhr H, Mohr N, Fröhlich S, Mehdi SQ, Bhattacharya SS, Weber BHF. Cloning and characterization of WDR17, a novel WD repeat-containing gene on chromosome 4q34. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1579:18-25. [PMID: 12401215 DOI: 10.1016/s0167-4781(02)00499-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
As part of our project to generate a catalogue of genes with potential relevance to human retinal disease, we have cloned a transcript abundantly expressed in the human retina and testis. Analysis of the deduced 1322 amino acid protein sequence demonstrates that it encodes a novel WD repeat protein, termed WDR17. The N-terminal moiety of the WDR17 protein is predicted to consist of at least 12 conserved WD repeats that likely adopts a beta-propeller-like structure. Homology searches with the C-terminal region revealed no similarity to known or hypothetical proteins. However, putative orthologous ESTs with 82-91% identity to the human cDNA were found in several mammalian species including rodents, pig and cattle, suggesting that WDR17 represents an evolutionarily novel subtype of WD repeat proteins with unique function(s) in higher eukaryotes. Temporal expression analysis in the murine eye showed that transcription of WDR17 begins prenatally, suggesting a functional role of the protein in the early stages of retinal development. Human WDR17 maps to the same chromosomal interval as the locus for autosomal recessive retinitis pigmentosa (RP29) on 4q34, making it a candidate for this disease gene. Sequencing of the entire coding region of WDR17 in an affected patient of the original RP29 pedigree has not revealed any disease-causing sequence variations likely excluding WDR17 as the gene underlying RP29.
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Affiliation(s)
- Heidi Stöhr
- Institut für Humangenetik, Biozentrum, Universität Würzburg, Am-Hubland, D-97074, Würzburg, Germany
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Sompornpailin K, Makita Y, Yamazaki M, Saito K. A WD-repeat-containing putative regulatory protein in anthocyanin biosynthesis in Perilla frutescens. PLANT MOLECULAR BIOLOGY 2002; 50:485-495. [PMID: 12369624 DOI: 10.1023/a:1019850921627] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The WD-repeat proteins are found in eukaryotes and play an important role in the regulation of a wide variety of cellular functions such as signal transduction, transcription, and proliferation. In this study, we have isolated a cDNA encoding a novel WD-repeat protein, PFWD, from the anthocyanin-pigmented leaves of Perilla frutescens using AN11 cDNA from Petunia hybrida as the probe. The C-terminal region of PFWD contains a WD repeat that is highly conserved in homologous proteins from a variety of organisms that do not produce anthocyanin such as yeast, nematodes and mammals. Transgenic Arabidopsis plants overexpressing PFWD exhibited phenotypic changes including enhancement of anthocyanin production and reduced viability. A study of the interaction between PFWD and anthocyanin regulatory proteins using a yeast two-hybrid system showed strong interaction between PFWD and MYC-RP, a MYC-like protein from P. frutescens. PFWD fusion proteins transiently expressed in onion epidermal cells were localized in the cytosol under both dark and light conditions. However, co-expression of PFWD and MYC-RP fusion proteins resulted in nuclear localization of PFWD. We propose a model of genetic regulation in which the PFWD protein acts in signal transduction process in a variety of pathways through protein interaction with MYC proteins.
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MESH Headings
- Amino Acid Sequence
- Anthocyanins/biosynthesis
- Arabidopsis/genetics
- Blotting, Southern
- Cloning, Molecular
- Cytoplasm/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- DNA, Plant/genetics
- Gene Expression Regulation, Plant/radiation effects
- Glucuronidase/genetics
- Glucuronidase/metabolism
- Green Fluorescent Proteins
- Light
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Microscopy, Fluorescence
- Molecular Sequence Data
- Onions/cytology
- Onions/metabolism
- Perilla/genetics
- Perilla/metabolism
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plants, Genetically Modified
- Protein Binding
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Messenger/radiation effects
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
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Affiliation(s)
- Kanokporn Sompornpailin
- Department of Molecular Biology and Biotechnology, Graduate School of Pharmaceutical Sciences, Chiba University, Japan
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65
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Xue F, Tian XC, Du F, Kubota C, Taneja M, Dinnyes A, Dai Y, Levine H, Pereira LV, Yang X. Aberrant patterns of X chromosome inactivation in bovine clones. Nat Genet 2002; 31:216-20. [PMID: 12032569 DOI: 10.1038/ng900] [Citation(s) in RCA: 245] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In mammals, epigenetic marks on the X chromosomes are involved in dosage compensation. Specifically, they are required for X chromosome inactivation (XCI), the random transcriptional silencing of one of the two X chromosomes in female cells during late blastocyst development. During natural reproduction, both X chromosomes are active in the female zygote. In somatic-cell cloning, however, the cloned embryos receive one active (Xa) and one inactive (Xi) X chromosome from the donor cells. Patterns of XCIhave been reported normal in cloned mice, but have yet to be investigated in other species. We examined allele-specific expression of the X-linked monoamine oxidase type A (MAOA) gene and the expression of nine additional X-linked genes in nine cloned XX calves. We found aberrant expression patterns in nine of ten X-linked genes and hypomethylation of Xist in organs of deceased clones. Analysis of MAOA expression in bovine placentae from natural reproduction revealed imprinted XCI with preferential inactivation of the paternal X chromosome. In contrast, we found random XCI in placentae of the deceased clones but completely skewed XCI in that of live clones. Thus, incomplete nuclear reprogramming may generate abnormal epigenetic marks on the X chromosomes of cloned cattle, affecting both random and imprinted XCI.
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Affiliation(s)
- Fei Xue
- Department of Animal Science and Center for Regenerative Biology, University of Connecticut, Storrs, Connecticut 06269, USA
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66
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Zhang J, Kalkum M, Chait BT, Roeder RG. The N-CoR-HDAC3 nuclear receptor corepressor complex inhibits the JNK pathway through the integral subunit GPS2. Mol Cell 2002; 9:611-23. [PMID: 11931768 DOI: 10.1016/s1097-2765(02)00468-9] [Citation(s) in RCA: 337] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The corepressors N-CoR and SMRT partner with histone deacetylases (HDACs) in diverse repression pathways. We report here that GPS2, a protein involved in intracellular signaling, is an integral subunit of the N-CoR-HDAC3 complex. We have determined structural motifs that direct the formation of a highly stable and active deacetylase complex. GPS2 and TBL1, another component of the N-CoR-HDAC3 complex, interact cooperatively with repression domain 1 of N-CoR to form a heterotrimeric structure and are indirectly linked to HDAC3 via an extended N-CoR SANT domain that also activates latent HDAC3 activity. More importantly, we show here that the N-CoR-HDAC3 complex inhibits JNK activation through the associated GPS2 subunit and thus could potentially provide an alternative mechanism for hormone-mediated antagonism of AP-1 function.
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Affiliation(s)
- Jinsong Zhang
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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67
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Abstract
Transcriptional repression, which plays a crucial role in diverse biological processes, is mediated in part by non-DNA-binding co-repressors. The closely related co-repressor proteins N-CoR and SMRT, although originally identified on the basis of their ability to associate with and confer transcriptional repression through nuclear receptors, have been shown to be recruited to many classes of transcription factor and are in fact components of multiple protein complexes containing histone deacetylase proteins. This association with histone deacetylase activity provides an important component of the mechanism that allows DNA-binding proteins interacting with N-CoR or SMRT to repress transcription of specific target genes. Both N-CoR and SMRT are important targets for cell signaling pathways, which influence their expression levels, subcellular localization and association with other proteins. Recently, the biological importance of these proteins has been revealed by studies of genetically engineered mice and human diseases such as acute promyelocytic leukemia (APL) and resistance to thyroid hormone(RTH).
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Affiliation(s)
- Kristen Jepsen
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 920393-0648, USA
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68
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Oetting WS. New insights into ocular albinism type 1 (OA1): Mutations and polymorphisms of the OA1 gene. Hum Mutat 2002; 19:85-92. [PMID: 11793467 DOI: 10.1002/humu.10034] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Albinism ocular type 1 (OA1) is an X-linked type of albinism that mainly effects pigment production in the eye, resulting in hypopigmentation of the retina, nystagmus, strabismus, foveal hypoplasia, abnormal crossing of the optic fibers, and reduced visual acuity. The OA1 gene is located on chromosome Xp22.32 and the coding sequence is divided into nine exons. The protein is an integral transmembrane protein that has weak similarities to G protein-coupled receptors. A total of 25 missense, two nonsense, nine frameshift, and five splicing mutations have been reported in the OA1 gene associated with OA1. There are also several deletions of some or all exons of the OA1 gene with deletions of exon 2 resulting from unequal crossing-over, due to flanking Alu repeats. Mutation and polymorphism data on this gene is available from the International Albinism Center - Albinism Database web site (http://www.cbc.umn.edu/tad).
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Affiliation(s)
- William S Oetting
- Department of Medicine and Institute of Human Genetics, University of Minnesota, Minneapolis, Minnesota, USA
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69
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Abstract
Thyroid hormones (THs) play critical roles in the differentiation, growth, metabolism, and physiological function of virtually all tissues. TH binds to receptors that are ligand-regulatable transcription factors belonging to the nuclear hormone receptor superfamily. Tremendous progress has been made recently in our understanding of the molecular mechanisms that underlie TH action. In this review, we present the major advances in our knowledge of the molecular mechanisms of TH action and their implications for TH action in specific tissues, resistance to thyroid hormone syndrome, and genetically engineered mouse models.
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Affiliation(s)
- P M Yen
- Molecular Regulation and Neuroendocrinology Section, Clinical Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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70
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Di Benedetto AJ, Klick Stoddard J, Glavan BJ. Cloning and molecular characterization of a novel gene encoding a WD-repeat protein expressed in restricted areas of adult rat brain. Gene 2001; 271:21-31. [PMID: 11410362 DOI: 10.1016/s0378-1119(01)00483-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We describe the cloning and characterization of a novel rat gene, bwd (brain-enriched WD), which encodes a protein with four copies of the WD amino acid motif, suggesting involvement in protein-protein interaction and a regulatory function in the cell. Northern analysis reveals two size classes of mRNA (1.8 and 2.2 kb), expressed in many adult tissues and developmental stages. Expression is highest in brain, where the longer of the two RNAs predominates. cDNA sequences show that both RNAs encode the identical protein, differing only in their 3' untranslated regions, where the longer transcript contains two RNA instability signals (AUUUA). In situ hybridization to bwd RNA in adult brain shows a highly restricted pattern, localizing expression mainly to the Purkinje and granule neurons of the cerebellum, the pyramidal cells of the hippocampus, and the dentate gyrus. In cryosections of rat cerebellum and kidney, BWD is shown by immunohistochemistry to be localized in the nucleus and cytoplasm of cerebellar Purkinje and granule neurons, and in predominantly the cytoplasm of cells surrounding kidney ducts. Taken together, these results suggest a specialized function for BWD in the brain. Sequence similarity comparisons with bwd reveal structural homologs of unknown function in human, mouse, Drosophila, Arabidopsis and C. elegans, and provide evidence that this set of sequences forms a new subfamily of WD-repeat genes. By sequence comparisons with expressed sequence tags (ESTs), the human homolog of bwd is predicted to reside in the chromosome 1q12-23 region, where several genetic diseases are known to map.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Brain/embryology
- Brain/metabolism
- Chromosome Mapping
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Female
- Gene Expression
- Gene Expression Regulation, Developmental
- Immunohistochemistry
- In Situ Hybridization
- Molecular Sequence Data
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Repetitive Sequences, Amino Acid/genetics
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tissue Distribution
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Affiliation(s)
- A J Di Benedetto
- Department of Biology, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085, USA.
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71
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Urnov FD, Wolffe AP. A necessary good: nuclear hormone receptors and their chromatin templates. Mol Endocrinol 2001; 15:1-16. [PMID: 11145735 DOI: 10.1210/mend.15.1.0589] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- F D Urnov
- Sangamo Biosciences Point Richmond Technical Center Richmond, California 94804, USA
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72
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Zhang X, Dormady SP, Basch RS. Identification of four human cDNAs that are differentially expressed by early hematopoietic progenitors. Exp Hematol 2000; 28:1286-96. [PMID: 11063877 DOI: 10.1016/s0301-472x(00)00539-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The molecular processes that maintain the stem cell pool are largely unknown. Using polymerase chain reaction-driven subtraction, we examined genes that are differentially expressed by early hematopoietic progenitors. We expected that identifying genes that are uniquely expressed by the earliest precursors would provide insight into the mechanism(s) through which stem cell number is maintained and differentiation is regulated. Using CD34(+)CD38(-) cells as starting material, we identified four mRNAs, expressed by these cells, that are either absent or present in reduced amounts in more mature CD34(+)CD38(+) cells. One of these cDNAs (C40) encodes a known member of the subfamily of protein phosphatases (CL100) that exhibits dual substrate specificity for phosphotyrosine- and phosphoserine/threonine-containing substrates and specifically inactivates MAP kinases. This phosphatase has been shown to play a role in regulating the differentiation of several cell types. The second cDNA (C23) is identical to LR11 (gp250), a member of the low-density lipoprotein receptor family. LR11 is unusual in that, in addition to 11 ligand-binding repeats, it contains a series of fibronectin type III repeats near its carboxyl terminal end that are similar to those found in cytokine receptors. It is highly expressed in developing brain, but hematopoietic expression has not been reported. The 178-bp fragment that we originally cloned is part of a 4,145-bp 3' untranslated region (UTR) that had not been previously sequenced and is among the largest human 3' UTRs ever reported. The other isolates (C21 and C12) do not correspond to known protein sequences. They are homologous to EST sequences from a fetal brain library. C21 encodes a previously unknown gene that is a member of the WD-40 family. An open reading frame encoding a 515 amino acid protein has been identified. Four mRNAs, differentially expressed by CD34(+)CD38(-) human bone marrow cells, have been identified. Although this population is highly enriched for early hematopoietic progenitors, none of these genes encodes a message whose expression is limited to the hematopoietic system. They all are expressed in a variety of tissues, suggesting that they are involved in processes that are fundamental to the development of many cell types. All of these cDNAs possess atypically long 3' UTRs, and one of them is among the longest ever described. Their differential expression by immature hematopoietic cells, in contrast to more mature cells, suggest that long 3' UTRs may be characteristic of genes that play a regulatory role during development.
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Affiliation(s)
- X Zhang
- Department of Pathology and the Kaplan Comprehensive Cancer Center, New York University School of Medicine, New York, NY, USA
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73
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Li J, Wang J, Wang J, Nawaz Z, Liu JM, Qin J, Wong J. Both corepressor proteins SMRT and N-CoR exist in large protein complexes containing HDAC3. EMBO J 2000; 19:4342-50. [PMID: 10944117 PMCID: PMC302030 DOI: 10.1093/emboj/19.16.4342] [Citation(s) in RCA: 490] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2000] [Revised: 06/21/2000] [Accepted: 06/26/2000] [Indexed: 11/13/2022] Open
Abstract
We present evidence that both corepressors SMRT and N-CoR exist in large protein complexes with estimated sizes of 1.5-2 MDa in HeLa nuclear extracts. Using a combination of conventional and immunoaffinity chromatography, we have successfully isolated a SMRT complex and identified histone deacetylase 3 (HDAC3) and transducin (beta)-like I (TBL1), a WD-40 repeat-containing protein, as the subunits of the purified SMRT complex. We show that the HDAC3-containing SMRT and N-CoR complexes can bind to unliganded thyroid hormone receptors (TRs) in vitro. We demonstrate further that in Xenopus oocytes, both SMRT and N-CoR also associate with HDAC3 in large protein complexes and that injection of antibodies against HDAC3 or SMRT/N-CoR led to a partial relief of repression by unliganded TR/RXR. These findings thus establish both SMRT and N-CoR complexes as bona fide HDAC-containing complexes and shed new light on the molecular pathways by which N-CoR and SMRT function in transcriptional repression.
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Affiliation(s)
- J Li
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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74
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Li D, Burch P, Gonzalez O, Kashork CD, Shaffer LG, Bachinski LL, Roberts R. Molecular cloning, expression analysis, and chromosome mapping of WDR6, a novel human WD-repeat gene. Biochem Biophys Res Commun 2000; 274:117-23. [PMID: 10903905 DOI: 10.1006/bbrc.2000.3012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The WD-repeat proteins are found in all eukaryotes and play an important role in the regulation of a wide variety of cellular functions such as signal transduction, transcription, and proliferation. Here we report on the cloning and characterization of a novel human WD-repeat gene, WDR6, which encodes a protein of 1121 amino acids and contains 11 WD-repeat units. WDR6 is unique since its 11 WD repeats are clustered into two distinct groups separated by a putative transmembrane domain. The WDR6 gene was mapped to chromosome 15q21 by fluorescence in situ hybridization. Northern analysis demonstrated that WDR6 is ubiquitously expressed in human adult and fetal tissues. WDR6 is not homologous to any previously identified human WD-repeat genes including WDR1 through WDR5. However, it was found to have significant sequence similarity with Arabidopsis thaliana hypothetical protein T7B11.12, yeast putative elongation factor G, and probable membrane protein YPL183c. All of them have been defined as WD-repeat proteins. Therefore, WDR6 is a novel protein and probably belongs to a highly conserved subfamily of WD-repeat proteins in which T7B11.12 and YPL183c are its distantly related members.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Blotting, Northern
- Chromosome Mapping
- Chromosomes, Human, Pair 15
- Cloning, Molecular
- DNA, Complementary/metabolism
- Heart Atria/metabolism
- Humans
- In Situ Hybridization, Fluorescence
- Membrane Proteins/biosynthesis
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Molecular Sequence Data
- Protein Structure, Tertiary
- RNA, Messenger/metabolism
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
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Affiliation(s)
- D Li
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
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75
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Guenther MG, Lane WS, Fischle W, Verdin E, Lazar MA, Shiekhattar R. A core SMRT corepressor complex containing HDAC3 and TBL1, a WD40-repeat protein linked to deafness. Genes Dev 2000; 14:1048-57. [PMID: 10809664 PMCID: PMC316569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2000] [Accepted: 03/21/2000] [Indexed: 02/16/2023]
Abstract
The corepressor SMRT mediates repression by thyroid hormone receptor (TR) as well as other nuclear hormone receptors and transcription factors. Here we report the isolation of a novel SMRT-containing complex from HeLa cells. This complex contains transducin beta-like protein 1 (TBL1), whose gene is mutated in human sensorineural deafness. It also contains HDAC3, a histone deacetylase not previously thought to interact with SMRT. TBL1 displays structural and functional similarities to Tup1 and Groucho corepressors, sharing their ability to interact with histone H3. In vivo, TBL1 is bridged to HDAC3 through SMRT and can potentiate repression by TR. Intriguingly, loss-of-function TRbeta mutations cause deafness in mice and humans. These results define a new TR corepressor complex with a physical link to histone structure and a potential biological link to deafness.
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Affiliation(s)
- M G Guenther
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Genetics, and The Penn Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104 USA
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76
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Guenther MG, Lane WS, Fischle W, Verdin E, Lazar MA, Shiekhattar R. A core SMRT corepressor complex containing HDAC3 and TBL1, a WD40-repeat protein linked to deafness. Genes Dev 2000. [DOI: 10.1101/gad.14.9.1048] [Citation(s) in RCA: 233] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The corepressor SMRT mediates repression by thyroid hormone receptor (TR) as well as other nuclear hormone receptors and transcription factors. Here we report the isolation of a novel SMRT-containing complex from HeLa cells. This complex contains transducin β-like protein 1 (TBL1), whose gene is mutated in human sensorineural deafness. It also contains HDAC3, a histone deacetylase not previously thought to interact with SMRT. TBL1 displays structural and functional similarities to Tup1 and Groucho corepressors, sharing their ability to interact with histone H3. In vivo, TBL1 is bridged to HDAC3 through SMRT and can potentiate repression by TR. Intriguingly, loss-of-function TRβ mutations cause deafness in mice and humans. These results define a new TR corepressor complex with a physical link to histone structure and a potential biological link to deafness.
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77
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Braverman N, Steel G, Lin P, Moser A, Moser H, Valle D. PEX7 gene structure, alternative transcripts, and evidence for a founder haplotype for the frequent RCDP allele, L292ter. Genomics 2000; 63:181-92. [PMID: 10673331 DOI: 10.1006/geno.1999.6080] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We recently reported cloning a cDNA encoding Pex7p, the peroxisomal PTS2 receptor. PEX7 mutations cause the peroxisome biogenesis disorder (PBD) rhizomelic chondrodysplasia punctata (RCDP). In a survey of 44 RCDP probands, we found that one PEX7 allele, L292ter, accounted for 50% of mutant PEX7 genes. Here we report the characterization of the PEX7 structural gene, which spans 102 kb on chromosome 6q21-q22.2 and contains at least 10 exons. In addition to the predominant full-length transcript, we identified eight smaller PEX7 transcripts generated by alternative exon splicing in several tissues. However, none of these splice forms was able to restore PTS2 protein import into peroxisomes when expressed in RCDP fibroblasts nor did they inhibit PTS2 protein import when expressed in normal fibroblasts. To determine whether the high frequency of the L292ter allele is due to a founder effect, we identified five polymorphic markers (four diallelic markers and one CA repeat) spanning the PEX7 gene. We show that all 12 L292ter homozygotes in our patient sample have an identical haplotype at these five sites, consistent with the hypothesis that the L292ter mutation arose once on an ancestral chromosome in the Caucasian population.
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Affiliation(s)
- N Braverman
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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78
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Ryan MM, Taylor P, Donald JA, Ouvrier RA, Morgan G, Danta G, Buckley MF, North KN. A novel syndrome of episodic muscle weakness maps to xp22.3. Am J Hum Genet 1999; 65:1104-13. [PMID: 10486330 PMCID: PMC1288244 DOI: 10.1086/302588] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
We describe a family with a novel disorder characterized by episodic muscle weakness and X-linked inheritance. Eight males in three generations demonstrate the characteristic features of the disorder. Episodes of severe muscle weakness are typically precipitated by febrile illness and affect the facial and extraocular musculature, as well as the trunk and limbs, and resolve spontaneously over a period of weeks to months. Younger members of the family are normal between episodes but during relapses show generalized weakness, ptosis, and fluctuations in strength. In some cases, fatigability can be demonstrated. The proband has late-onset chronic weakness and fatigability. The clinical phenotype has features suggestive both of the congenital myasthenic syndromes and of ion-channel disorders such as the periodic paralyses. We have localized the responsible gene to chromosome Xp22.3, with a maximum two-point LOD score of 4. 52 at a recombination fraction of.0, between OACA2 and DXS9985.
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Affiliation(s)
- Monique M. Ryan
- Department of Neurology, Neurogenetics Research Unit, and Department of Paediatrics, University of Sydney, New Children's Hospital, Molecular and Cytogenetics Unit, South Eastern Area Laboratory Services, Prince of Wales Hospital, and Department of Biological Sciences, Macquarie University, Sydney; Department of Medical Genetics, Sydney Children's Hospital, Randwick, New South Wales; and Department of Neurology, The Canberra Hospital, Canberra, Australia
| | - Peter Taylor
- Department of Neurology, Neurogenetics Research Unit, and Department of Paediatrics, University of Sydney, New Children's Hospital, Molecular and Cytogenetics Unit, South Eastern Area Laboratory Services, Prince of Wales Hospital, and Department of Biological Sciences, Macquarie University, Sydney; Department of Medical Genetics, Sydney Children's Hospital, Randwick, New South Wales; and Department of Neurology, The Canberra Hospital, Canberra, Australia
| | - Jennifer A. Donald
- Department of Neurology, Neurogenetics Research Unit, and Department of Paediatrics, University of Sydney, New Children's Hospital, Molecular and Cytogenetics Unit, South Eastern Area Laboratory Services, Prince of Wales Hospital, and Department of Biological Sciences, Macquarie University, Sydney; Department of Medical Genetics, Sydney Children's Hospital, Randwick, New South Wales; and Department of Neurology, The Canberra Hospital, Canberra, Australia
| | - Robert A. Ouvrier
- Department of Neurology, Neurogenetics Research Unit, and Department of Paediatrics, University of Sydney, New Children's Hospital, Molecular and Cytogenetics Unit, South Eastern Area Laboratory Services, Prince of Wales Hospital, and Department of Biological Sciences, Macquarie University, Sydney; Department of Medical Genetics, Sydney Children's Hospital, Randwick, New South Wales; and Department of Neurology, The Canberra Hospital, Canberra, Australia
| | - Graeme Morgan
- Department of Neurology, Neurogenetics Research Unit, and Department of Paediatrics, University of Sydney, New Children's Hospital, Molecular and Cytogenetics Unit, South Eastern Area Laboratory Services, Prince of Wales Hospital, and Department of Biological Sciences, Macquarie University, Sydney; Department of Medical Genetics, Sydney Children's Hospital, Randwick, New South Wales; and Department of Neurology, The Canberra Hospital, Canberra, Australia
| | - Gytis Danta
- Department of Neurology, Neurogenetics Research Unit, and Department of Paediatrics, University of Sydney, New Children's Hospital, Molecular and Cytogenetics Unit, South Eastern Area Laboratory Services, Prince of Wales Hospital, and Department of Biological Sciences, Macquarie University, Sydney; Department of Medical Genetics, Sydney Children's Hospital, Randwick, New South Wales; and Department of Neurology, The Canberra Hospital, Canberra, Australia
| | - Michael F. Buckley
- Department of Neurology, Neurogenetics Research Unit, and Department of Paediatrics, University of Sydney, New Children's Hospital, Molecular and Cytogenetics Unit, South Eastern Area Laboratory Services, Prince of Wales Hospital, and Department of Biological Sciences, Macquarie University, Sydney; Department of Medical Genetics, Sydney Children's Hospital, Randwick, New South Wales; and Department of Neurology, The Canberra Hospital, Canberra, Australia
| | - Kathryn N. North
- Department of Neurology, Neurogenetics Research Unit, and Department of Paediatrics, University of Sydney, New Children's Hospital, Molecular and Cytogenetics Unit, South Eastern Area Laboratory Services, Prince of Wales Hospital, and Department of Biological Sciences, Macquarie University, Sydney; Department of Medical Genetics, Sydney Children's Hospital, Randwick, New South Wales; and Department of Neurology, The Canberra Hospital, Canberra, Australia
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