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Mao JH, Perez-Losada J, Wu D, Delrosario R, Tsunematsu R, Nakayama KI, Brown K, Bryson S, Balmain A. Fbxw7/Cdc4 is a p53-dependent, haploinsufficient tumour suppressor gene. Nature 2005; 432:775-9. [PMID: 15592418 DOI: 10.1038/nature03155] [Citation(s) in RCA: 309] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Accepted: 11/03/2004] [Indexed: 12/16/2022]
Abstract
The FBXW7/hCDC4 gene encodes a ubiquitin ligase implicated in the control of chromosome stability. Here we identify the mouse Fbxw7 gene as a p53-dependent tumour suppressor gene by using a mammalian genetic screen for p53-dependent genes involved in tumorigenesis. Radiation-induced lymphomas from p53+/- mice, but not those from p53-/- mice, show frequent loss of heterozygosity and a 10% mutation rate of the Fbxw7 gene. Fbxw7+/- mice have greater susceptibility to radiation-induced tumorigenesis, but most tumours retain and express the wild-type allele, indicating that Fbxw7 is a haploinsufficient tumour suppressor gene. Loss of Fbxw7 alters the spectrum of tumours that develop in p53 deficient mice to include a range of tumours in epithelial tissues such as the lung, liver and ovary. Mouse embryo fibroblasts from Fbxw7-deficient mice, or wild-type mouse cells expressing Fbxw7 small interfering RNA, have higher levels of Aurora-A kinase, c-Jun and Notch4, but not of cyclin E. We propose that p53-dependent loss of Fbxw7 leads to genetic instability by mechanisms that might involve the activation of Aurora-A, providing a rationale for the early occurrence of these mutations in human cancers.
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Affiliation(s)
- Jian-Hua Mao
- Cancer Research Institute, University of California at San Francisco, 2340 Sutter Street, San Francisco, California 94143, USA
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202
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Welcker M, Clurman BE. The SV40 large T antigen contains a decoy phosphodegron that mediates its interactions with Fbw7/hCdc4. J Biol Chem 2004; 280:7654-8. [PMID: 15611062 DOI: 10.1074/jbc.m413377200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Cell transformation by simian virus 40 (SV40) results mostly from the highly oncogenic activities of the large T antigen (LT), which corrupts the cellular checkpoint mechanisms that guard cell division and the transcription, replication, and repair of DNA. The most prominent LT targets are the retinoblastoma protein (pRb) and p53. Here we report that LT binds directly to Fbw7, the substrate recognition component of the SCF(Fbw7) ubiquitin ligase and a human tumor suppressor. LT binding mislocalizes the nucleolar Fbw7gamma isoform to the nucleoplasm. Interestingly, the binding of LT to Fbw7 occurs via a decoy phospho-epitope within the C terminus of LT that closely mimics the consensus Cdc4 phospho-degron found within Fbw7 substrates. We demonstrate that, using this mode of interaction, LT can interfere with Fbw7-driven cyclin E turnover in vivo and causes increased cyclin E-associated kinase activity. Our data suggest that LT competes with cellular proteins for Fbw7 binding in a substrate-like fashion.
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Affiliation(s)
- Markus Welcker
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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203
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Nakayama K, Nagahama H, Minamishima YA, Miyake S, Ishida N, Hatakeyama S, Kitagawa M, Iemura SI, Natsume T, Nakayama KI. Skp2-mediated degradation of p27 regulates progression into mitosis. Dev Cell 2004; 6:661-72. [PMID: 15130491 DOI: 10.1016/s1534-5807(04)00131-5] [Citation(s) in RCA: 295] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Revised: 03/19/2004] [Accepted: 03/24/2004] [Indexed: 12/24/2022]
Abstract
Although Skp2 has been thought to mediate the degradation of p27 at the G(1)-S transition, Skp2(-/-) cells exhibit accumulation of p27 in S-G(2) phase with overreplication. We demonstrate that Skp2(-/-)p27(-/-) mice do not exhibit the overreplication phenotype, suggesting that p27 accumulation is required for its development. Hepatocytes of Skp2(-/-) mice entered the endoduplication cycle after mitogenic stimulation, whereas this phenotype was not apparent in Skp2(-/-)p27(-/-) mice. Cdc2-associated kinase activity was lower in Skp2(-/-) cells than in wild-type cells, and a reduction in Cdc2 activity was sufficient to induce overreplication. The lack of p27 degradation in G(2) phase in Skp2(-/-) cells may thus result in suppression of Cdc2 activity and consequent inhibition of entry into M phase. These data suggest that p27 proteolysis is necessary for the activation of not only Cdk2 but also Cdc2, and that Skp2 contributes to regulation of G(2)-M progression by mediating the degradation of p27.
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Affiliation(s)
- Keiko Nakayama
- National Institute of Advanced Industrial Science and Technology (AIST), Biological Information Research Center, Tokyo 135-0064, Japan.
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205
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Yada M, Hatakeyama S, Kamura T, Nishiyama M, Tsunematsu R, Imaki H, Ishida N, Okumura F, Nakayama K, Nakayama KI. Phosphorylation-dependent degradation of c-Myc is mediated by the F-box protein Fbw7. EMBO J 2004; 23:2116-25. [PMID: 15103331 PMCID: PMC424394 DOI: 10.1038/sj.emboj.7600217] [Citation(s) in RCA: 629] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2003] [Accepted: 03/31/2004] [Indexed: 01/17/2023] Open
Abstract
The F-box protein Skp2 mediates c-Myc ubiquitylation by binding to the MB2 domain. However, the turnover of c-Myc is largely dependent on phosphorylation of threonine-58 and serine-62 in MB1, residues that are often mutated in cancer. We now show that the F-box protein Fbw7 interacts with and thereby destabilizes c-Myc in a manner dependent on phosphorylation of MB1. Whereas wild-type Fbw7 promoted c-Myc turnover in cells, an Fbw7 mutant lacking the F-box domain delayed it. Furthermore, depletion of Fbw7 by RNA interference increased both the abundance and transactivation activity of c-Myc. Accumulation of c-Myc was also apparent in mouse Fbw7-/- embryonic stem cells. These observations suggest that two F-box proteins, Fbw7 and Skp2, differentially regulate c-Myc stability by targeting MB1 and MB2, respectively.
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Affiliation(s)
- Masayoshi Yada
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Fukuoka, Japan
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
| | - Shigetsugu Hatakeyama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Fukuoka, Japan
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
| | - Takumi Kamura
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Fukuoka, Japan
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
| | - Masaaki Nishiyama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Fukuoka, Japan
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
| | - Ryosuke Tsunematsu
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Fukuoka, Japan
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
| | - Hiroyuki Imaki
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Fukuoka, Japan
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
| | - Noriko Ishida
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
- Division of Developmental Biology, Center for Translational and Advanced Animal Research on Human Diseases, Tohoku University School of Medicine, Sendai, Miyagi, Japan
| | - Fumihiko Okumura
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Fukuoka, Japan
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
| | - Keiko Nakayama
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
- Division of Developmental Biology, Center for Translational and Advanced Animal Research on Human Diseases, Tohoku University School of Medicine, Sendai, Miyagi, Japan
| | - Keiichi I Nakayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Fukuoka, Japan
- CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan. Tel.: +81 92 642 6815; Fax: +81 92 642 6819; E-mail:
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