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Chapat C, Chettab K, Simonet P, Wang P, De La Grange P, Le Romancer M, Corbo L. Alternative splicing of CNOT7 diversifies CCR4-NOT functions. Nucleic Acids Res 2017; 45:8508-8523. [PMID: 28591869 PMCID: PMC5737658 DOI: 10.1093/nar/gkx506] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 05/26/2017] [Indexed: 12/11/2022] Open
Abstract
The CCR4-associated factor CAF1, also called CNOT7, is a catalytic subunit of the CCR4–NOT complex, which has been implicated in all aspects of the mRNA life cycle, from mRNA synthesis in the nucleus to degradation in the cytoplasm. In human cells, alternative splicing of the CNOT7 gene yields a second CNOT7 transcript leading to the formation of a shorter protein, CNOT7 variant 2 (CNOT7v2). Biochemical characterization indicates that CNOT7v2 interacts with CCR4–NOT subunits, although it does not bind to BTG proteins. We report that CNOT7v2 displays a distinct expression profile in human tissues, as well as a nuclear sub-cellular localization compared to CNOT7v1. Despite a conserved DEDD nuclease domain, CNOT7v2 is unable to degrade a poly(A) tail in vitro and preferentially associates with the protein arginine methyltransferase PRMT1 to regulate its activity. Using both in vitro and in cellulo systems, we have also demonstrated that CNOT7v2 regulates the inclusion of CD44 variable exons. Altogether, our findings suggest a preferential involvement of CNOT7v2 in nuclear processes, such as arginine methylation and alternative splicing, rather than mRNA turnover. These observations illustrate how the integration of a splicing variant inside CCR4–NOT can diversify its cell- and tissue-specific functions.
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Affiliation(s)
- Clément Chapat
- Univ. Lyon, Université Lyon 1, Inserm U1052, CNRS UMR5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France
| | - Kamel Chettab
- Univ. Lyon, Université Lyon 1, Inserm U1052, CNRS UMR5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France
| | - Pierre Simonet
- Univ. Lyon, Université Lyon 1, Inserm U1052, CNRS UMR5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France
| | - Peng Wang
- McGill University, Department of Biochemistry, 1160 Pine Avenue West, Montreal, QC H3A 1A3, Canada
| | | | - Muriel Le Romancer
- Univ. Lyon, Université Lyon 1, Inserm U1052, CNRS UMR5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France
| | - Laura Corbo
- Univ. Lyon, Université Lyon 1, Inserm U1052, CNRS UMR5286, Centre Léon Bérard, Centre de Recherche en Cancérologie de Lyon, Lyon 69008, France
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Ho KJ, Do NL, Otu HH, Dib MJ, Ren X, Enjyoji K, Robson SC, Terwilliger EF, Karp SJ. Tob1 is a constitutively expressed repressor of liver regeneration. J Exp Med 2010; 207:1197-208. [PMID: 20513747 PMCID: PMC2882843 DOI: 10.1084/jem.20092434] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 04/28/2010] [Indexed: 01/20/2023] Open
Abstract
How proliferative and inhibitory signals integrate to control liver regeneration remains poorly understood. A screen for antiproliferative factors repressed after liver injury identified transducer of ErbB2.1 (Tob1), a member of the PC3/BTG1 family of mito-inhibitory molecules as a target for further evaluation. Tob1 protein decreases after 2/3 hepatectomy in mice secondary to posttranscriptional mechanisms. Deletion of Tob1 increases hepatocyte proliferation and accelerates restoration of liver mass after hepatectomy. Down-regulation of Tob1 is required for normal liver regeneration, and Tob1 controls hepatocyte proliferation in a dose-dependent fashion. Tob1 associates directly with both Caf1 and cyclin-dependent kinase (Cdk) 1 and modulates Cdk1 kinase activity. In addition, Tob1 has significant effects on the transcription of critical cell cycle components, including E2F target genes and genes involved in p53 signaling. We provide direct evidence that levels of an inhibitory factor control the rate of liver regeneration, and we identify Tob1 as a crucial check point molecule that modulates the expression and activity of cell cycle proteins.
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Affiliation(s)
- Karen J. Ho
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
- Department of Surgery, Brigham and Women’s Hospital, Boston, MA 02115
| | - Nhue L. Do
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
- Department of Surgery, Brigham and Women’s Hospital, Boston, MA 02115
| | - Hasan H. Otu
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
| | - Martin J. Dib
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
| | - Xianghui Ren
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
| | - Keiichi Enjyoji
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
| | - Simon C. Robson
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
| | - Ernest F. Terwilliger
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
| | - Seth J. Karp
- Department of Surgery, Department of Medicine, and the Transplant Institute, Beth Israel Deaconess Medical Center, Boston, MA 02215
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Yang X, Morita M, Wang H, Suzuki T, Yang W, Luo Y, Zhao C, Yu Y, Bartlam M, Yamamoto T, Rao Z. Crystal structures of human BTG2 and mouse TIS21 involved in suppression of CAF1 deadenylase activity. Nucleic Acids Res 2008; 36:6872-81. [PMID: 18974182 PMCID: PMC2588512 DOI: 10.1093/nar/gkn825] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
BTG2 is the prototypical member of the TOB family and is known to be involved in cell growth, differentiation and DNA repair. As a transcriptional co-regulator, BTG2 interacts with CCR4-associated factor 1 (CAF1) and POP2 (CALIF), which are key components of the general CCR4/NOT multi-subunit transcription complex, and which are reported to play distinct roles as nucleases involved in mRNA deadenylation. Here we report the crystal structures of human BTG2 and mouse TIS21 to 2.3 Å and 2.2 Å resolution, respectively. The structures reveal the putative CAF1 binding site. CAF1 deadenylase assays were performed with wild-type BTG2 and mutants that disrupt the interaction with CAF1. The results reveal the suppressive role of BTG2 in the regulation of CAF1 deadenylase activity. Our study provides insights into the formation of the BTG2-CAF1 complex and the potential role of BTG2 in the regulation of CAF1.
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Affiliation(s)
- Xiuna Yang
- Laboratory of Structural Biology, Tsinghua University, Beijing, China
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