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Ng HY, Adly AN, Whelpley DH, Suhandynata RT, Zhou H, Morgan DO. Phosphate-binding pocket on cyclin B governs CDK substrate phosphorylation and mitotic timing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582599. [PMID: 38464173 PMCID: PMC10925351 DOI: 10.1101/2024.02.28.582599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Cell cycle progression is governed by complexes of the cyclin-dependent kinases (CDKs) and their regulatory subunits cyclin and Cks1. CDKs phosphorylate hundreds of substrates, often at multiple sites. Multisite phosphorylation depends on Cks1, which binds initial priming phosphorylation sites to promote secondary phosphorylation at other sites. Here, we describe a similar role for a recently discovered phosphate-binding pocket (PP) on B-type cyclins. Mutation of the PP in Clb2, the major mitotic cyclin of budding yeast, alters bud morphology and delays the onset of anaphase. Using phosphoproteomics in vivo and kinase reactions in vitro, we find that mutation of the PP reduces phosphorylation of several CDK substrates, including the Bud6 subunit of the polarisome and the Cdc16 and Cdc27 subunits of the anaphase-promoting complex/cyclosome. We conclude that the cyclin PP, like Cks1, controls the timing of multisite phosphorylation on CDK substrates, thereby helping to establish the robust timing of cell-cycle events.
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Affiliation(s)
- Henry Y. Ng
- Department of Physiology, University of California San Francisco, San Francisco CA
| | - Armin N. Adly
- Department of Physiology, University of California San Francisco, San Francisco CA
| | - Devon H. Whelpley
- Department of Physiology, University of California San Francisco, San Francisco CA
| | - Raymond T. Suhandynata
- School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla CA
- Department of Pathology, University of California San Diego, La Jolla CA
| | - Huilin Zhou
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla CA
| | - David O. Morgan
- Department of Physiology, University of California San Francisco, San Francisco CA
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Fu C, Davy A, Holmes S, Sun S, Yadav V, Gusa A, Coelho MA, Heitman J. Dynamic genome plasticity during unisexual reproduction in the human fungal pathogen Cryptococcus deneoformans. PLoS Genet 2021; 17:e1009935. [PMID: 34843473 PMCID: PMC8670703 DOI: 10.1371/journal.pgen.1009935] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 12/14/2021] [Accepted: 11/08/2021] [Indexed: 12/30/2022] Open
Abstract
Genome copy number variation occurs during each mitotic and meiotic cycle and it is crucial for organisms to maintain their natural ploidy. Defects in ploidy transitions can lead to chromosome instability, which is a hallmark of cancer. Ploidy in the haploid human fungal pathogen Cryptococcus neoformans is exquisitely orchestrated and ranges from haploid to polyploid during sexual development and under various environmental and host conditions. However, the mechanisms controlling these ploidy transitions are largely unknown. During C. deneoformans (formerly C. neoformans var. neoformans, serotype D) unisexual reproduction, ploidy increases prior to the onset of meiosis, can be independent from cell-cell fusion and nuclear fusion, and likely occurs through an endoreplication pathway. To elucidate the molecular mechanisms underlying this ploidy transition, we identified twenty cell cycle-regulating genes encoding cyclins, cyclin-dependent kinases (CDK), and CDK regulators. We characterized four cyclin genes and two CDK regulator genes that were differentially expressed during unisexual reproduction and contributed to diploidization. To detect ploidy transition events, we generated a ploidy reporter, called NURAT, which can detect copy number increases via double selection for nourseothricin-resistant, uracil-prototrophic cells. Utilizing this ploidy reporter, we showed that ploidy transition from haploid to diploid can be detected during the early phases of unisexual reproduction. Interestingly, selection for the NURAT reporter revealed several instances of segmental aneuploidy of multiple chromosomes, which conferred azole resistance in some isolates. These findings provide further evidence of ploidy plasticity in fungi with significant biological and public health implications. Ploidy is an intrinsic fundamental feature of all eukaryotic organisms, and ploidy variation and maintenance are critical to the organism survival and evolution. Fungi exhibit exquisite plasticity in ploidy variation in adaptation to various environmental stresses. For example, the haploid opportunistic human fungal pathogen C. deneoformans can generate diploid blastospores during unisexual reproduction and also forms polyploid titan cells during host infection; however, the mechanisms underlying these ploidy transitions are largely unknown. In this study, we elucidated the genetic regulatory circuitry governing ploidy duplication during C. deneoformans unisexual reproduction through the identification and characterization of cell cycle regulators that are differentially expressed during unisexual reproduction. We showed that four cyclin and two cyclin-dependent kinase regulator genes function in concert to orchestrate ploidy transition during unisexual reproduction. To trace and track ploidy transition events, we also generated a ploidy reporter and revealed the formation of segmental aneuploidy in addition to diploidization, illustrating the diverse mechanisms of genome plasticity in C. deneoformans.
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Affiliation(s)
- Ci Fu
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Aaliyah Davy
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Simeon Holmes
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Vikas Yadav
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Asiya Gusa
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Marco A. Coelho
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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Ghanbarpour A, Santos EM, Pinger C, Assar Z, Hossaini Nasr S, Vasileiou C, Spence D, Borhan B, Geiger JH. Human Cellular Retinol Binding Protein II Forms a Domain-Swapped Trimer Representing a Novel Fold and a New Template for Protein Engineering. Chembiochem 2020; 21:3192-3196. [PMID: 32608180 PMCID: PMC8220890 DOI: 10.1002/cbic.202000405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 06/29/2020] [Indexed: 11/07/2022]
Abstract
Domain-swapping is a mechanism for evolving new protein structure from extant scaffolds, and has been an efficient protein-engineering strategy for tailoring functional diversity. However, domain swapping can only be exploited if it can be controlled, especially in cases where various folds can coexist. Herein, we describe the structure of a domain-swapped trimer of the iLBP family member hCRBPII, and suggest a mechanism for domain-swapped trimerization. It is further shown that domain-swapped trimerization can be favored by strategic installation of a disulfide bond, thus demonstrating a strategy for fold control. We further show the domain-swapped trimer to be a useful protein design template by installing a high-affinity metal binding site through the introduction of a single mutation, taking advantage of its threefold symmetry. Together, these studies show how nature can promote oligomerization, stabilize a specific oligomer, and generate new function with minimal changes to the protein sequence.
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Affiliation(s)
- Alireza Ghanbarpour
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
- Yale University Medical School, Department of Cell Biology, 333 S. Cedar Street, New Haven, CT 06510, USA
| | - Elizabeth M Santos
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
- Dow Performance Silicones, 2200W Salzburg Road, Midland, MI 48686, USA
| | - Cody Pinger
- Department of Biomedical Engineering, Michigan State University, 775 Woodlot Drive, East Lansing, MI 48823, USA
| | - Zahra Assar
- Cayman Chemical, 1180 East Ellsworth Road, Ann Arbor, MI 48108, USA
| | - Seyedmehdi Hossaini Nasr
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - Dana Spence
- Department of Biomedical Engineering, Michigan State University, 775 Woodlot Drive, East Lansing, MI 48823, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - James H Geiger
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
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Genome-Wide Analysis of Cell Cycle-Regulating Genes in the Symbiotic Dinoflagellate Breviolum minutum. G3-GENES GENOMES GENETICS 2019; 9:3843-3853. [PMID: 31551286 PMCID: PMC6829154 DOI: 10.1534/g3.119.400363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
A delicate relationship exists between reef-building corals and their photosynthetic endosymbionts. Unfortunately, this relationship can be disrupted, with corals expelling these algae when temperatures rise even marginally above the average summer maximum. Interestingly, several studies indicate that failure of corals to regulate symbiont cell divisions at high temperatures may underlie this disruption; increased proliferation of symbionts may stress host cells by over-production of reactive oxygen species or by disrupting the flow of nutrients. This needs to be further investigated, so to begin deciphering the molecular mechanisms controlling the cell cycle in these organisms, we used a computational approach to identify putative cell cycle-regulating genes in the genome of the dinoflagellate Breviolum minutum. This species is important as an endosymbiont of Aiptasia pallida—an anemone that is used as a model for studying coral biology. We then correlated expression of these putative cell cycle genes with cell cycle phase in diurnally growing B. minutum in culture. This approach allowed us to identify a cyclin/cyclin-dependent kinase pair that may function in the G1/S transition—a likely point for coral cells to exert control over algal cell divisions.
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Parnell EJ, Stillman DJ. Multiple Negative Regulators Restrict Recruitment of the SWI/SNF Chromatin Remodeler to the HO Promoter in Saccharomyces cerevisiae. Genetics 2019; 212:1181-1204. [PMID: 31167839 PMCID: PMC6707452 DOI: 10.1534/genetics.119.302359] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/30/2019] [Indexed: 01/22/2023] Open
Abstract
Activation of the Saccharomyces cerevisiae HO promoter is highly regulated, requiring the ordered recruitment of activators and coactivators and allowing production of only a few transcripts in mother cells within a short cell cycle window. We conducted genetic screens to identify the negative regulators of HO expression necessary to limit HO transcription. Known repressors of HO (Ash1 and Rpd3) were identified, as well as several additional chromatin-associated factors including the Hda1 histone deacetylase, the Isw2 chromatin remodeler, and the corepressor Tup1 We also identified clusters of HO promoter mutations that suggested roles for the Dot6/Tod6 (PAC site) and Ume6 repression pathways. We used ChIP assays with synchronized cells to validate the involvement of these factors and map the association of Ash1, Dot6, and Ume6 with the HO promoter to a brief window in the cell cycle between binding of the initial activating transcription factor and initiation of transcription. We found that Ash1 and Ume6 each recruit the Rpd3 histone deacetylase to HO, and their effects are additive. In contrast, Rpd3 was not recruited significantly to the PAC site, suggesting this site has a distinct mechanism for repression. Increases in HO expression and SWI/SNF recruitment were all additive upon loss of Ash1, Ume6, and PAC site factors, indicating the convergence of independent pathways for repression. Our results demonstrate that multiple protein complexes are important for limiting the spread of SWI/SNF-mediated nucleosome eviction across the HO promoter, suggesting that regulation requires a delicate balance of activities that promote and repress transcription.
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Affiliation(s)
- Emily J Parnell
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84112
| | - David J Stillman
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84112
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Ellederova Z, Del Rincon S, Koncicka M, Susor A, Kubelka M, Sun D, Spruck C. CKS1 Germ Line Exclusion Is Essential for the Transition from Meiosis to Early Embryonic Development. Mol Cell Biol 2019; 39:e00590-18. [PMID: 30988159 PMCID: PMC6580707 DOI: 10.1128/mcb.00590-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/25/2019] [Accepted: 04/04/2019] [Indexed: 12/11/2022] Open
Abstract
Cell division cycle (Cdc) kinase subunit (CKS) proteins bind cyclin-dependent kinases (CDKs) and play important roles in cell division control and development, though their precise molecular functions are not fully understood. Mammals express two closely related paralogs called CKS1 and CKS2, but only CKS2 is expressed in the germ line, indicating that it is solely responsible for regulating CDK functions in meiosis. Using cks2-/- knockout mice, we show that CKS2 is a crucial regulator of maturation-promoting factor (MPF; CDK1-cyclin A/B) activity in meiosis. cks2-/- oocytes display reduced and delayed MPF activity during meiotic progression, leading to defects in germinal vesicle breakdown (GVBD), anaphase-promoting complex/cyclosome (APC/C) activation, and meiotic spindle assembly. cks2-/- germ cells express significantly reduced levels of the MPF components CDK1 and cyclins A1/B1. Additionally, injection of MPF plus CKS2, but not MPF alone, restored normal GVBD in cks2-/- oocytes, demonstrating that GVBD is driven by a CKS2-dependent function of MPF. Moreover, we generated cks2cks1/cks1 knock-in mice and found that CKS1 can compensate for CKS2 in meiosis in vivo, but homozygous embryos arrested development at the 2- to 5-cell stage. Collectively, our results show that CKS2 is a crucial regulator of MPF functions in meiosis and that its paralog, CKS1, must be excluded from the germ line for proper embryonic development.
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Affiliation(s)
- Zdenka Ellederova
- Tumor Initiation and Maintenance Program, Sanford | Burnham | Prebys Medical Discovery Institute, La Jolla, California, USA
- Laboratory of Cell Regeneration and Plasticity, Institute of Animal Physiology and Genetics, Czech Academy of Science, Libechov, Czech Republic
| | - Sonia Del Rincon
- Tumor Initiation and Maintenance Program, Sanford | Burnham | Prebys Medical Discovery Institute, La Jolla, California, USA
- Gerald Bronfman Department of Oncology, McGill University Lady Davis Institute, Segal Cancer Centre-Jewish General Hospital, Montreal, Quebec, Canada
| | - Marketa Koncicka
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, Czech Academy of Science, Libechov, Czech Republic
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Andrej Susor
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, Czech Academy of Science, Libechov, Czech Republic
| | - Michal Kubelka
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, Czech Academy of Science, Libechov, Czech Republic
| | - Dahui Sun
- Tumor Initiation and Maintenance Program, Sanford | Burnham | Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Charles Spruck
- Tumor Initiation and Maintenance Program, Sanford | Burnham | Prebys Medical Discovery Institute, La Jolla, California, USA
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Kriseman M, Monsivais D, Agno J, Masand RP, Creighton CJ, Matzuk MM. Uterine double-conditional inactivation of Smad2 and Smad3 in mice causes endometrial dysregulation, infertility, and uterine cancer. Proc Natl Acad Sci U S A 2019; 116:3873-3882. [PMID: 30651315 PMCID: PMC6397514 DOI: 10.1073/pnas.1806862116] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
SMAD2 and SMAD3 are downstream proteins in the transforming growth factor-β (TGF β) signaling pathway that translocate signals from the cell membrane to the nucleus, bind DNA, and control the expression of target genes. While SMAD2/3 have important roles in the ovary, we do not fully understand the roles of SMAD2/3 in the uterus and their implications in the reproductive system. To avoid deleterious effects of global deletion, and given previous data showing redundant function of Smad2 and Smad3, a double-conditional knockout was generated using progesterone receptor-cre (Smad2/3 cKO) mice. Smad2/3 cKO mice were infertile due to endometrial hyperproliferation observed as early as 6 weeks of postnatal life. Endometrial hyperplasia worsened with age, and all Smad2/3 cKO mice ultimately developed bulky endometrioid-type uterine cancers with 100% mortality by 8 months of age. The phenotype was hormone-dependent and could be prevented with removal of the ovaries at 6 weeks of age but not at 12 weeks. Uterine tumor epithelium was associated with decreased expression of steroid biosynthesis genes, increased expression of inflammatory response genes, and abnormal expression of cell cycle checkpoint genes. Our results indicate the crucial role of SMAD2/3 in maintaining normal endometrial function and confirm the hormone-dependent nature of SMAD2/3 in the uterus. The hyperproliferation of the endometrium affected both implantation and maintenance of pregnancy. Our findings generate a mouse model to study the roles of SMAD2/3 in the uterus and serve to provide insight into the mechanism by which the endometrium can escape the plethora of growth regulatory proteins.
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Affiliation(s)
- Maya Kriseman
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030
- Reproductive Endocrinology and Infertility, Baylor College of Medicine/Texas Children's Hospital Women's Pavilion, Houston, TX 77030
| | - Diana Monsivais
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030
- Center for Drug Discovery, Baylor College of Medicine, Houston, TX 77030
| | - Julio Agno
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030
| | - Ramya P Masand
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030
| | - Chad J Creighton
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX 77030
| | - Martin M Matzuk
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030;
- Center for Drug Discovery, Baylor College of Medicine, Houston, TX 77030
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX 77030
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8
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Yue X, Que Y, Deng S, Xu L, Oses-Ruiz M, Talbot NJ, Peng Y, Wang Z. The cyclin dependent kinase subunit Cks1 is required for infection-associated development of the rice blast fungusMagnaporthe oryzae. Environ Microbiol 2017; 19:3959-3981. [DOI: 10.1111/1462-2920.13796] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 03/30/2017] [Accepted: 05/08/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Xiaofeng Yue
- State Key Laboratory for Rice Biology; Institute of Biotechnology, Zhejiang University; Hangzhou 310058, China
| | - Yawei Que
- State Key Laboratory for Rice Biology; Institute of Biotechnology, Zhejiang University; Hangzhou 310058, China
| | - Shuzhen Deng
- State Key Laboratory for Rice Biology; Institute of Biotechnology, Zhejiang University; Hangzhou 310058, China
| | - Lin Xu
- State Key Laboratory for Rice Biology; Institute of Biotechnology, Zhejiang University; Hangzhou 310058, China
| | - Miriam Oses-Ruiz
- School of Biosciences; University of Exeter, Geoffrey Pope Building; Exeter EX4 4QD UK
| | - Nicholas J. Talbot
- School of Biosciences; University of Exeter, Geoffrey Pope Building; Exeter EX4 4QD UK
| | - Youliang Peng
- State Key Laboratory of Agribiotechnology and MOA Key Laboratory of Plant Pathology; China Agricultural University; Beijing 100193, People's Republic of China
| | - Zhengyi Wang
- State Key Laboratory for Rice Biology; Institute of Biotechnology, Zhejiang University; Hangzhou 310058, China
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Xu L, Fan S, Zhao J, Zhou P, Chu S, Luo J, Wen Q, Chen L, Wen S, Wang L, Shi L. Increased expression of Cks1 protein is associated with lymph node metastasis and poor prognosis in nasopharyngeal carcinoma. Diagn Pathol 2017; 12:2. [PMID: 28061788 PMCID: PMC5219755 DOI: 10.1186/s13000-016-0589-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 12/06/2016] [Indexed: 12/12/2022] Open
Abstract
Background The Cks1 protein is an essential factor in regulating cell cycle by mediating the ubiquitination of CDK inhibitor p27kip1. It has been reported that aberrant expression of Cks1 and p27kip1 proteins was found in various tumors and related to initiation and progression of carcinomas. However, the potential roles which Cks1 and p27KIP1 proteins play in NPC remain unclear. This study aims to examine the expression status of Cks1 and p27kip1 and their possible prognostic significance in NPC. Methods Paraffin-embedded specimens with NPC (n = 168) and non-tumor nasopharyngeal tissues (n = 49) were analyzed by IHC. Results Expression of Cks1 increased in NPC tissues compared with non-tumor nasopharyngeal tissues (P < 0.05), whereas p27kip1 protein frequently expressed in non-tumor nasopharyngeal tissues compared with NPC tissues (P < 0.05). There was a significant reverse correlation between Cks1 and p27kip1 protein expression in NPC (r = −0.189, P < 0.05).In addition, Kaplan-Meier survival curve showed that there was a significant tendency of shorter overall survival (OS) in NPC patients with Cks1 positive expression compared to negative ones, especially in patients with lymph node metastasis (P < 0.001, respectively). But there was no significance between p27kip1 expression and survival viability of NPC patients. Multivariate Cox regression analysis further identified increased expression of Cks1 was the independent poor prognostic factor for NPC (p = 0.13). Conclusion Our research found expression of Cks1 increased and was inverse to the expression of p27KIP1. High expression of Cks1 was significantly associated with lymph node metastasis and survival status in NPC. In addition, the abnormally high level of Cks1 protein was proved to be an independent poor prognostic factor in NPC. These results may provide novel clue for NPC therapy method. Electronic supplementary material The online version of this article (doi:10.1186/s13000-016-0589-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lina Xu
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China
| | - Songqing Fan
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China
| | - Jin Zhao
- Department of Clinical Laboratory, Hunan Cancer Hospital, Changsha, Hunan, China
| | - Peng Zhou
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China
| | - Shuzhou Chu
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China
| | - Jiadi Luo
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China
| | - Qiuyuan Wen
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China
| | - Lingjiao Chen
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China
| | - Sailan Wen
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China
| | - Li Wang
- Department of Chest Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Lei Shi
- Department of Pathology, The Second Xiangya Hospital of Central South University, Renmin Road 139, Changsha, Hunan, 410000, China.
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Reid RJD, Du X, Sunjevaric I, Rayannavar V, Dittmar J, Bryant E, Maurer M, Rothstein R. A Synthetic Dosage Lethal Genetic Interaction Between CKS1B and PLK1 Is Conserved in Yeast and Human Cancer Cells. Genetics 2016; 204:807-819. [PMID: 27558135 PMCID: PMC5068864 DOI: 10.1534/genetics.116.190231] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 08/11/2016] [Indexed: 12/29/2022] Open
Abstract
The CKS1B gene located on chromosome 1q21 is frequently amplified in breast, lung, and liver cancers. CKS1B codes for a conserved regulatory subunit of cyclin-CDK complexes that function at multiple stages of cell cycle progression. We used a high throughput screening protocol to mimic cancer-related overexpression in a library of Saccharomyces cerevisiae mutants to identify genes whose functions become essential only when CKS1 is overexpressed, a synthetic dosage lethal (SDL) interaction. Mutations in multiple genes affecting mitotic entry and mitotic exit are highly enriched in the set of SDL interactions. The interactions between Cks1 and the mitotic entry checkpoint genes require the inhibitory activity of Swe1 on the yeast cyclin-dependent kinase (CDK), Cdc28. In addition, the SDL interactions of overexpressed CKS1 with mutations in the mitotic exit network are suppressed by modulating expression of the CDK inhibitor Sic1. Mutation of the polo-like kinase Cdc5, which functions in both the mitotic entry and mitotic exit pathways, is lethal in combination with overexpressed CKS1 Therefore we investigated the effect of targeting the human Cdc5 ortholog, PLK1, in breast cancers with various expression levels of human CKS1B Growth inhibition by PLK1 knockdown correlates with increased CKS1B expression in published tumor cell data sets, and this correlation was confirmed using shRNAs against PLK1 in tumor cell lines. In addition, we overexpressed CKS1B in multiple cell lines and found increased sensitivity to PLK1 knockdown and PLK1 drug inhibition. Finally, combined inhibition of WEE1 and PLK1 results in less apoptosis than predicted based on an additive model of the individual inhibitors, showing an epistatic interaction and confirming a prediction of the yeast data. Thus, identification of a yeast SDL interaction uncovers conserved genetic interactions that can affect human cancer cell viability.
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Affiliation(s)
- Robert J D Reid
- Department Genetics and Development, Columbia University Medical Center, New York, New York 10032
| | - Xing Du
- Department of Medicine, Columbia University Medical Center, New York, New York 10032
| | - Ivana Sunjevaric
- Department Genetics and Development, Columbia University Medical Center, New York, New York 10032
| | - Vinayak Rayannavar
- Department of Medicine, Columbia University Medical Center, New York, New York 10032
| | - John Dittmar
- Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Eric Bryant
- Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Matthew Maurer
- Department of Medicine, Columbia University Medical Center, New York, New York 10032
| | - Rodney Rothstein
- Department Genetics and Development, Columbia University Medical Center, New York, New York 10032
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11
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Kümper S, Mardakheh FK, McCarthy A, Yeo M, Stamp GW, Paul A, Worboys J, Sadok A, Jørgensen C, Guichard S, Marshall CJ. Rho-associated kinase (ROCK) function is essential for cell cycle progression, senescence and tumorigenesis. eLife 2016; 5:e12994. [PMID: 26765561 PMCID: PMC4798951 DOI: 10.7554/elife.12203] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 01/13/2016] [Indexed: 12/12/2022] Open
Abstract
Rho-associated kinases 1 and 2 (ROCK1/2) are Rho-GTPase effectors that control key aspects of the actin cytoskeleton, but their role in proliferation and cancer initiation or progression is not known. Here, we provide evidence that ROCK1 and ROCK2 act redundantly to maintain actomyosin contractility and cell proliferation and that their loss leads to cell-cycle arrest and cellular senescence. This phenotype arises from down-regulation of the essential cell-cycle proteins CyclinA, CKS1 and CDK1. Accordingly, while the loss of either Rock1 or Rock2 had no negative impact on tumorigenesis in mouse models of non-small cell lung cancer and melanoma, loss of both blocked tumor formation, as no tumors arise in which both Rock1 and Rock2 have been genetically deleted. Our results reveal an indispensable role for ROCK, yet redundant role for isoforms 1 and 2, in cell cycle progression and tumorigenesis, possibly through the maintenance of cellular contractility.
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Affiliation(s)
- Sandra Kümper
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
| | - Faraz K Mardakheh
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
| | - Afshan McCarthy
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
| | - Maggie Yeo
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
| | - Gordon W Stamp
- Experimental Pathology Laboratory, Cancer Research UK London Research Institute, London, United Kingdom
| | - Angela Paul
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
| | - Jonathan Worboys
- Cancer Research UK Manchester Institute, Manchester, United Kingdom
| | - Amine Sadok
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
| | - Claus Jørgensen
- Cancer Research UK Manchester Institute, Manchester, United Kingdom
| | - Sabrina Guichard
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
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12
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Wu L, Wang Y, Liu Y, Yu S, Xie H, Shi X, Qin S, Ma F, Tan TZ, Thiery JP, Chen L. A central role for TRPS1 in the control of cell cycle and cancer development. Oncotarget 2015; 5:7677-90. [PMID: 25277197 PMCID: PMC4202153 DOI: 10.18632/oncotarget.2291] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The eukaryotic cell cycle is controlled by a complex regulatory network, which is still poorly understood. Here we demonstrate that TRPS1, an atypical GATA factor, modulates cell proliferation and controls cell cycle progression. Silencing TRPS1 had a differential effect on the expression of nine key cell cycle-related genes. Eight of these genes are known to be involved in the regulation of the G2 phase and the G2/M transition of the cell cycle. Using cell synchronization studies, we confirmed that TRPS1 plays an important role in the control of cells in these phases of the cell cycle. We also show that silencing TRPS1 controls the expression of 53BP1, but not TP53. TRPS1 silencing also decreases the expression of two histone deacetylases, HDAC2 and HDAC4, as well as the overall HDAC activity in the cells, and leads to the subsequent increase in the acetylation of histone4 K16 but not of histone3 K9 or K18. Finally, we demonstrate that TRPS1 expression is elevated in luminal breast cancer cells and luminal breast cancer tissues as compared with other breast cancer subtypes. Overall, our study proposes that TRPS1 acts as a central hub in the control of cell cycle and proliferation during cancer development.
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Affiliation(s)
- Lele Wu
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Science, Southeast University, Nanjing, PR China. Contributed equally to this work
| | - Yuzhi Wang
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Science, Southeast University, Nanjing, PR China. Contributed equally to this work
| | - Yan Liu
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Science, Southeast University, Nanjing, PR China
| | - Shiyi Yu
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Science, Southeast University, Nanjing, PR China
| | - Hao Xie
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Science, Southeast University, Nanjing, PR China
| | - Xingjuan Shi
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Science, Southeast University, Nanjing, PR China
| | - Sheng Qin
- Laboratory for Comparative Genomics and Bioinformatics and Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
| | - Fei Ma
- Laboratory for Comparative Genomics and Bioinformatics and Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
| | - Tuan Zea Tan
- Cancer Science Institute, National University of Singapore, 14 Medical Drive, Singapore
| | - Jean Paul Thiery
- Cancer Science Institute, National University of Singapore, 14 Medical Drive, Singapore. Institute of Molecular and Cell Biology, A*STAR, 61 Biopolis Drive, Singapore. Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore
| | - Liming Chen
- The Key Laboratory of Developmental Genes and Human Disease, Ministry of Education, Institute of Life Science, Southeast University, Nanjing, PR China
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13
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Lu D, Hsiao JY, Davey NE, Van Voorhis VA, Foster SA, Tang C, Morgan DO. Multiple mechanisms determine the order of APC/C substrate degradation in mitosis. ACTA ACUST UNITED AC 2014; 207:23-39. [PMID: 25287299 PMCID: PMC4195823 DOI: 10.1083/jcb.201402041] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
To ensure proper mitotic progression, robust ordering of the destruction of APC/CCdc20 substrates is driven by the integration of molecular mechanisms ranging from phosphorylation-dependent interaction with substrates to sensing of the status of the spindle assembly checkpoint. The ubiquitin protein ligase anaphase-promoting complex or cyclosome (APC/C) controls mitosis by promoting ordered degradation of securin, cyclins, and other proteins. The mechanisms underlying the timing of APC/C substrate degradation are poorly understood. We explored these mechanisms using quantitative fluorescence microscopy of GFP-tagged APC/CCdc20 substrates in living budding yeast cells. Degradation of the S cyclin, Clb5, begins early in mitosis, followed 6 min later by the degradation of securin and Dbf4. Anaphase begins when less than half of securin is degraded. The spindle assembly checkpoint delays the onset of Clb5 degradation but does not influence securin degradation. Early Clb5 degradation depends on its interaction with the Cdk1–Cks1 complex and the presence of a Cdc20-binding “ABBA motif” in its N-terminal region. The degradation of securin and Dbf4 is delayed by Cdk1-dependent phosphorylation near their Cdc20-binding sites. Thus, a remarkably diverse array of mechanisms generates robust ordering of APC/CCdc20 substrate destruction.
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Affiliation(s)
- Dan Lu
- Department of Physiology and Department of Biochemistry and Biophysics and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158
| | - Jennifer Y Hsiao
- Department of Physiology and Department of Biochemistry and Biophysics and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158
| | - Norman E Davey
- Department of Physiology and Department of Biochemistry and Biophysics and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158
| | - Vanessa A Van Voorhis
- Department of Physiology and Department of Biochemistry and Biophysics and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158
| | - Scott A Foster
- Department of Physiology and Department of Biochemistry and Biophysics and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158
| | - Chao Tang
- Center for Quantitative Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - David O Morgan
- Department of Physiology and Department of Biochemistry and Biophysics and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158
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14
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Kõivomägi M, Örd M, Iofik A, Valk E, Venta R, Faustova I, Kivi R, Balog ERM, Rubin SM, Loog M. Multisite phosphorylation networks as signal processors for Cdk1. Nat Struct Mol Biol 2013; 20:1415-24. [PMID: 24186061 PMCID: PMC3855452 DOI: 10.1038/nsmb.2706] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 09/26/2013] [Indexed: 12/27/2022]
Abstract
The order and timing of cell-cycle events is controlled by changing substrate specificity and different activity thresholds of cyclin-dependent kinases (CDKs). However, it is not understood how a single protein kinase can trigger hundreds of switches in a sufficiently time-resolved fashion. We show that cyclin-Cdk1-Cks1-dependent phosphorylation of multisite targets in Saccharomyces cerevisiae is controlled by key substrate parameters including distances between phosphorylation sites, distribution of serines and threonines as phosphoacceptors and positioning of cyclin-docking motifs. The component mediating the key interactions in this process is Cks1, the phosphoadaptor subunit of the cyclin-Cdk1-Cks1 complex. We propose that variation of these parameters within networks of phosphorylation sites in different targets provides a wide range of possibilities for differential amplification of Cdk1 signals, thus providing a mechanism to generate a wide range of thresholds in the cell cycle.
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Affiliation(s)
| | - Mihkel Örd
- Institute of Technology, University of Tartu, Estonia
| | - Anna Iofik
- Institute of Technology, University of Tartu, Estonia
| | - Ervin Valk
- Institute of Technology, University of Tartu, Estonia
| | - Rainis Venta
- Institute of Technology, University of Tartu, Estonia
| | | | - Rait Kivi
- Institute of Technology, University of Tartu, Estonia
| | - Eva Rose M. Balog
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, USA
| | - Seth M. Rubin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, USA
| | - Mart Loog
- Institute of Technology, University of Tartu, Estonia
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15
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Cks confers specificity to phosphorylation-dependent CDK signaling pathways. Nat Struct Mol Biol 2013; 20:1407-14. [PMID: 24186063 DOI: 10.1038/nsmb.2707] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 09/11/2013] [Indexed: 12/12/2022]
Abstract
Cks is an evolutionarily conserved protein that regulates cyclin-dependent kinase (CDK) activity. Clarifying the underlying mechanisms and cellular contexts of Cks function is critical because Cks is essential for proper cell growth, and its overexpression has been linked to cancer. We observe that budding-yeast Cks associates with select phosphorylated sequences in cell cycle-regulatory proteins. We characterize the molecular interactions responsible for this specificity and demonstrate that Cks enhances CDK activity in response to specific priming phosphosites. Identification of the binding consensus sequence allows us to identify putative Cks-directed CDK substrates and binding partners. We characterize new Cks-binding sites in the mitotic regulator Wee1 and discover a new role for Cks in regulating CDK activity at mitotic entry. Together, our results portray Cks as a multifunctional phosphoadaptor that serves as a specificity factor for CDK activity.
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16
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Lee SW, Lin CY, Tian YF, Sun DP, Lin LC, Chen LT, Hsing CH, Huang CT, Hsu HP, Huang HY, Wu LC, Li CF, Shiue YL. Overexpression of CDC28 protein kinase regulatory subunit 1B confers an independent prognostic factor in nasopharyngeal carcinoma. APMIS 2013; 122:206-14. [PMID: 23879533 DOI: 10.1111/apm.12136] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 05/15/2013] [Indexed: 12/28/2022]
Abstract
Data mining on public domain identified that CDC28 protein kinase regulatory subunit 1B (CKS1B) transcript was highly expressed in nasopharyngeal carcinoma (NPC). The expression of CKS1B protein and its clinicopathological associations in patients with NPC were further evaluated. Immunoexpression of CKS1B was retrospectively assessed in biopsies of 124 consecutive NPC patients without initial distant metastasis and treated with consistent guidelines. The correlations between CKS1B immunoexpression levels and clinicopathological features, as well as patient survivals, were analyzed. High CKS1B expression (49.2%) was correlated with the 7th American Joint Committee on Cancer (AJCC) stage (p = 0.014). In multivariate analyses, high CKS1B expression emerged as an independent prognostic factor for worse disease-specific survival (p < 0.001), metastasis-free survival (p < 0.001), and local recurrence-free survival (p = 0.001). High expression of CKS1B is common and associated with adverse prognostic factors and might confer tumor aggressiveness through dysregulation of the cyclin-dependent protein kinase (intrinsic regulatory activity) during cell cycle progression.
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Affiliation(s)
- Sung-Wei Lee
- Department of Radiation Oncology, Chi-Mei Medical Center, Tainan, Taiwan
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17
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Khattar V, Thottassery JV. Cks1: Structure, Emerging Roles and Implications in Multiple Cancers. ACTA ACUST UNITED AC 2013; 4:1341-1354. [PMID: 24563807 PMCID: PMC3930463 DOI: 10.4236/jct.2013.48159] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Deregulation of the cell cycle results in loss of normal control mechanisms that prevent aberrant cell proliferation and cancer progression. Regulation of the cell cycle is a highly complex process with many layers of control. One of these mechanisms involves timely degradation of CDK inhibitors (CKIs) like p27Kip1 by the ubiquitin proteasomal system (UPS). Cks1 is a 9 kDa protein which is frequently overexpressed in different tumor subtypes, and has pleiotropic roles in cell cycle progression, many of which remain to be fully characterized. One well characterized molecular role of Cks1 is that of an essential adaptor that regulates p27Kip1 abundance by facilitating its interaction with the SCF-Skp2 E3 ligase which appends ubiquitin to p27Kip1 and targets it for degradation through the UPS. In addition, emerging research has uncovered p27Kip1-independent roles of Cks1 which have provided crucial insights into how it may be involved in cancer progression. We review here the structural features of Cks1 and their functional implications, and also some recently identified Cks1 roles and their involvement in breast and other cancers.
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Affiliation(s)
| | - Jaideep V Thottassery
- Southern Research Institute, Birmingham, USA ; University of Alabama Comprehensive Cancer Center, Birmingham, USA
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18
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Cks1 promotion of S phase entry and proliferation is independent of p27Kip1 suppression. Mol Cell Biol 2012; 32:2416-27. [PMID: 22508990 DOI: 10.1128/mcb.06771-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cks1 is an activator of the SCF(Skp2) ubiquitin ligase complex that targets the cell cycle inhibitor p27(Kip1) for degradation. The loss of Cks1 results in p27(Kip1) accumulation and decreased proliferation and inhibits tumorigenesis. We identify here a function of Cks1 in mammalian cell cycle regulation that is independent of p27(Kip1). Specifically, Cks1(-/-); p27(Kip1-/-) mouse embryonic fibroblasts retain defects in the G(1)-S phase transition that are coupled with decreased Cdk2-associated kinase activity and defects in proliferation that are associated with Cks1 loss. Furthermore, concomitant loss of Cks1 does not rescue the tumor suppressor function of p27(Kip1) that is manifest in various organs of p27(Kip1-/-) mice. In contrast, defects in mitotic entry and premature senescence manifest in Cks1(-/-) cells are p27(Kip1) dependent. Collectively, these findings establish p27(Kip1)-independent functions of Cks1 in regulating the G(1)-S transition.
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19
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Kõivomägi M, Valk E, Venta R, Iofik A, Lepiku M, Balog ERM, Rubin SM, Morgan DO, Loog M. Cascades of multisite phosphorylation control Sic1 destruction at the onset of S phase. Nature 2011; 480:128-31. [PMID: 21993622 PMCID: PMC3228899 DOI: 10.1038/nature10560] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 09/20/2011] [Indexed: 11/09/2022]
Abstract
Multisite phosphorylation of proteins has been proposed to transform a graded protein kinase signal into an ultrasensitive switch-like response. Although many multiphosphorylated targets have been identified, the dynamics and sequence of individual phosphorylation events within the multisite phosphorylation process have never been thoroughly studied. In Saccharomyces cerevisiae, the initiation of S phase is thought to be governed by complexes of Cdk1 and Cln cyclins that phosphorylate six or more sites on the Clb5-Cdk1 inhibitor Sic1, directing it to SCF-mediated destruction. The resulting Sic1-free Clb5-Cdk1 complex triggers S phase. Here, we demonstrate that Sic1 destruction depends on a more complex process in which both Cln2-Cdk1 and Clb5-Cdk1 act in processive multiphosphorylation cascades leading to the phosphorylation of a small number of specific phosphodegrons. The routes of these phosphorylation cascades are shaped by precisely oriented docking interactions mediated by cyclin-specific docking motifs in Sic1 and by Cks1, the phospho-adaptor subunit of Cdk1. Our results indicate that Clb5-Cdk1-dependent phosphorylation generates positive feedback that is required for switch-like Sic1 destruction. Our evidence for a docking network within clusters of phosphorylation sites uncovers a new level of complexity in Cdk1-dependent regulation of cell cycle transitions, and has general implications for the regulation of cellular processes by multisite phosphorylation.
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Affiliation(s)
- Mardo Kõivomägi
- Institute of Technology, University of Tartu, Tartu 50411, Estonia
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20
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Balog ERM, Saetern OC, Finch W, Hoeft CO, Thai V, Harvey SL, Kellogg DR, Rubin SM. The Structure of a Monomeric Mutant Cks Protein Reveals Multiple Functions for a Conserved Hinge-Region Proline. J Mol Biol 2011; 411:520-8. [DOI: 10.1016/j.jmb.2011.05.045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 05/25/2011] [Accepted: 05/27/2011] [Indexed: 11/17/2022]
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21
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Shi L, Wang S, Zangari M, Xu H, Cao TM, Xu C, Wu Y, Xiao F, Liu Y, Yang Y, Salama M, Li G, Tricot G, Zhan F. Over-expression of CKS1B activates both MEK/ERK and JAK/STAT3 signaling pathways and promotes myeloma cell drug-resistance. Oncotarget 2011; 1:22-33. [PMID: 20930946 PMCID: PMC2949973 DOI: 10.18632/oncotarget.105] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Here we demonstrate the crucial role of CKS1B in multiple myeloma (MM) progression and define CKS1B-mediated SKP2/p27Kip1-independent down-stream signaling pathways. Forced-expression of CKS1B in MM cells increased cell multidrug-resistance. CKS1B activates STAT3 and MEK/ERK pathways. In contrast, SKP2 knockdown or p27Kip1 over-expression resulted in activation of the STAT3 and MEK/ERK pathways. Further investigations showed that BCL2 is a downstream target of MEK/ERK signaling. Stimulation of STAT3 and MEK/ERK signaling pathways partially abrogated CKS1B knockdown induced MM cell death and growth inhibition. Targeting STAT3 and MEK/ ERK signaling pathways by specific inhibitors induced significant MM cell death and growth inhibition in CKS1B-overexpressing MM cells and their combinations resulted in synergy. Thus, our findings provide a rationale for targeting STAT3 and MEK/ERK/ BCL2 signaling in aggressive CKS1B-overexpressing MM.
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Affiliation(s)
- Lei Shi
- Division of Hematology/BMT/myeloma Program, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA
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22
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Gitter A, Klein-Seetharaman J, Gupta A, Bar-Joseph Z. Discovering pathways by orienting edges in protein interaction networks. Nucleic Acids Res 2010; 39:e22. [PMID: 21109539 PMCID: PMC3045580 DOI: 10.1093/nar/gkq1207] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Modern experimental technology enables the identification of the sensory proteins that interact with the cells’ environment or various pathogens. Expression and knockdown studies can determine the downstream effects of these interactions. However, when attempting to reconstruct the signaling networks and pathways between these sources and targets, one faces a substantial challenge. Although pathways are directed, high-throughput protein interaction data are undirected. In order to utilize the available data, we need methods that can orient protein interaction edges and discover high-confidence pathways that explain the observed experimental outcomes. We formalize the orientation problem in weighted protein interaction graphs as an optimization problem and present three approximation algorithms based on either weighted Boolean satisfiability solvers or probabilistic assignments. We use these algorithms to identify pathways in yeast. Our approach recovers twice as many known signaling cascades as a recent unoriented signaling pathway prediction technique and over 13 times as many as an existing network orientation algorithm. The discovered paths match several known signaling pathways and suggest new mechanisms that are not currently present in signaling databases. For some pathways, including the pheromone signaling pathway and the high-osmolarity glycerol pathway, our method suggests interesting and novel components that extend current annotations.
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Affiliation(s)
- Anthony Gitter
- Computer Science Department, Carnegie Mellon University, Pittsburgh, PA, USA
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23
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Boruc J, Mylle E, Duda M, De Clercq R, Rombauts S, Geelen D, Hilson P, Inzé D, Van Damme D, Russinova E. Systematic localization of the Arabidopsis core cell cycle proteins reveals novel cell division complexes. PLANT PHYSIOLOGY 2010; 152:553-65. [PMID: 20018602 PMCID: PMC2815867 DOI: 10.1104/pp.109.148643] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 12/08/2009] [Indexed: 05/18/2023]
Abstract
Cell division depends on the correct localization of the cyclin-dependent kinases that are regulated by phosphorylation, cyclin proteolysis, and protein-protein interactions. Although immunological assays can define cell cycle protein abundance and localization, they are not suitable for detecting the dynamic rearrangements of molecular components during cell division. Here, we applied an in vivo approach to trace the subcellular localization of 60 Arabidopsis (Arabidopsis thaliana) core cell cycle proteins fused to green fluorescent proteins during cell division in tobacco (Nicotiana tabacum) and Arabidopsis. Several cell cycle proteins showed a dynamic association with mitotic structures, such as condensed chromosomes and the preprophase band in both species, suggesting a strong conservation of targeting mechanisms. Furthermore, colocalized proteins were shown to bind in vivo, strengthening their localization-function connection. Thus, we identified unknown spatiotemporal territories where functional cell cycle protein interactions are most likely to occur.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Eugenia Russinova
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, B–9052 Ghent, Belgium (J.B., E.M., M.D., R.D.C., S.R., P.H., D.I., D.V.D., E.R.); Department of Plant Biotechnology and Genetics, Ghent University, B–9052 Ghent, Belgium (J.B., E.M., M.D., R.D.C., S.R., P.H., D.I., D.V.D., E.R.); and Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, B–9000 Ghent, Belgium (D.G.)
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24
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Abstract
Genetic and biochemical studies have provided considerable insight into the multiple functions of cyclin-dependent kinase subunit (cks)1 in cell division cycle. In addition to enhanced substrate targeting by specific ubiquitin ligases SCF(skp2) and APC/C, its direct interaction with proteasome components normalizes multiple cell cycle regulators. Importantly, it also acts as a transcriptional regulator. cks1 overexpression reflects poor prognosis in malignancy thus indicating its possible role in tumour diagnosis and management. The present review compiles the multiple functional roles of cks1 in cell division with specific emphasis on its molecular mechanisms. Its docking functions and the possible downstream proteolytic and transcriptional targets are described. The spatial configuration of cks1-cdk2 complex and the structural organization of cks1-p27-skp2 assembly required for p27 ubiquitination are discussed in detail. In addition to enhanced p27 degradation, the possible other mechanisms which underlie its pathological functions in human cancer progression are also discussed. Though there are apparent gaps in information, the turnover mechanism of cks1 is well addressed and presents opportunity to exploit the target for disease management.
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Affiliation(s)
- Anand Krishnan
- Translational Cancer Research Laboratory, Department of Molecular Medicine, Rajiv Gandhi Centre for Biotechnology, Kerala, India
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25
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Cyclin-dependent kinase-associated proteins Cks1 and Cks2 are essential during early embryogenesis and for cell cycle progression in somatic cells. Mol Cell Biol 2008; 28:5698-709. [PMID: 18625720 DOI: 10.1128/mcb.01833-07] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cks proteins associate with cyclin-dependent kinases and have therefore been assumed to play a direct role in cell cycle regulation. Mammals have two paralogs, Cks1 and Cks2, and individually deleting the gene encoding either in the mouse has previously been shown not to impact viability. In this study we show that simultaneously disrupting CKS1 and CKS2 leads to embryonic lethality, with embryos dying at or before the morula stage after only two to four cell division cycles. RNA interference (RNAi)-mediated silencing of CKS genes in mouse embryonic fibroblasts (MEFs) or HeLa cells causes cessation of proliferation. In MEFs CKS silencing leads to cell cycle arrest in G(2), followed by rereplication and polyploidy. This phenotype can be attributed to impaired transcription of the CCNB1, CCNA2, and CDK1 genes, encoding cyclin B1, cyclin A, and Cdk1, respectively. Restoration of cyclin B1 expression rescues the cell cycle arrest phenotype conferred by RNAi-mediated Cks protein depletion. Consistent with a direct role in transcription, Cks2 is recruited to chromatin in general and to the promoter regions and open reading frames of genes requiring Cks function with a cell cycle periodicity that correlates with their transcription.
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26
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Ubersax JA, Ferrell JE. Mechanisms of specificity in protein phosphorylation. Nat Rev Mol Cell Biol 2007; 8:530-41. [PMID: 17585314 DOI: 10.1038/nrm2203] [Citation(s) in RCA: 998] [Impact Index Per Article: 58.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A typical protein kinase must recognize between one and a few hundred bona fide phosphorylation sites in a background of approximately 700,000 potentially phosphorylatable residues. Multiple mechanisms have evolved that contribute to this exquisite specificity, including the structure of the catalytic site, local and distal interactions between the kinase and substrate, the formation of complexes with scaffolding and adaptor proteins that spatially regulate the kinase, systems-level competition between substrates, and error-correction mechanisms. The responsibility for the recognition of substrates by protein kinases appears to be distributed among a large number of independent, imperfect specificity mechanisms.
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Affiliation(s)
- Jeffrey A Ubersax
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California 94305-5174, USA.
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27
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Tsai YS, Chang HC, Chuang LY, Hung WC. RNA silencing of Cks1 induced G2/M arrest and apoptosis in human lung cancer cells. IUBMB Life 2006; 57:583-9. [PMID: 16118116 DOI: 10.1080/15216540500215531] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cdc kinase subunit 1 (Cks1) has been shown to involve in the regulation of cell cycle progression and p27Kip1 degradation. To define the role of Cks1 in lung tumorigenesis, we examined the expression of Cks1 in human lung cancer cell lines and tested the effect of Cks1-specific small interfering RNA (siRNA) on these cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot analysis showed that Cks1 was highly expressed in human lung cancer cells. Transfection of Cks1 siRNA down-regulated Cdc2 kinase activity and induced G2/M arrest in Cks1- overexpressing H358 lung cancer cells. Long-term treatment of Cks1 siRNA induced caspase activation and apoptosis in H358 cells. On the contrary, Cks1 siRNA did not affect viability of normal human lung fibroblasts under the same experimental condition. Collectively, our results suggest that Cks1 participates in the steps of lung tumorigenesis and this gene may be a target for the treatment of lung cancer.
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Affiliation(s)
- Yi-Shan Tsai
- Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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28
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Yu VPCC, Baskerville C, Grünenfelder B, Reed SI. A Kinase-Independent Function of Cks1 and Cdk1 in Regulation of Transcription. Mol Cell 2005; 17:145-51. [PMID: 15629725 DOI: 10.1016/j.molcel.2004.11.020] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 10/04/2004] [Accepted: 10/27/2004] [Indexed: 11/29/2022]
Abstract
We describe a function in transcription for the Saccharomyces cerevisiae cell cycle regulatory cyclin-dependent kinase Cdc28 (Cdk1) and its interacting protein, Cks1. The Cks1/Cdc28 complex is recruited to multiple coding regions in the genome and is necessary for efficient expression of a significant subset of genes. This transcriptional role is mediated through a requirement of Cdc28/Cks1 for recruiting proteasomes to coding regions. However, it is independent of the protein kinase activity of Cdc28. In the absence of Cks1, neither Cdc28 nor the proteasome can be recruited. Consequently, there is a failure to maintain efficient transcription.
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Affiliation(s)
- Veronica P C C Yu
- Department of Molecular Biology, MB-7, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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29
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Morris MC, Kaiser P, Rudyak S, Baskerville C, Watson MH, Reed SI. Cks1-dependent proteasome recruitment and activation of CDC20 transcription in budding yeast. Nature 2003; 423:1009-13. [PMID: 12827207 DOI: 10.1038/nature01720] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2003] [Accepted: 05/06/2003] [Indexed: 11/09/2022]
Abstract
Cks proteins are small evolutionarily conserved proteins that interact genetically and physically with cyclin-dependent kinases. However, in spite of a large body of genetic, biochemical and structural research, no compelling unifying model of their functions has emerged. Here we show, by investigating the essential role of Cks1 in Saccharomyces cerevisiae, that the protein is primarily involved in promoting mitosis by modulating the transcriptional activation of the APC/C protein-ubiquitin ligase activator Cdc20. Cks1 is required for both the periodic dissociation of Cdc28 kinase from the CDC20 promoter and the periodic association of the proteasome with the promoter. We propose that the essential role of Cks1 is to recruit the proteasome to, and/or dissociate the Cdc28 kinase from, the CDC20 promoter, thus facilitating transcription by remodelling transcriptional complexes or chromatin associated with the CDC20 gene.
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Affiliation(s)
- May C Morris
- The Scripps Research Institute, Department of Molecular Biology, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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30
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Spruck CH, de Miguel MP, Smith APL, Ryan A, Stein P, Schultz RM, Lincoln AJ, Donovan PJ, Reed SI. Requirement of Cks2 for the first metaphase/anaphase transition of mammalian meiosis. Science 2003; 300:647-50. [PMID: 12714746 DOI: 10.1126/science.1084149] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We generated mice lacking Cks2, one of two mammalian homologs of the yeast Cdk1-binding proteins, Suc1 and Cks1, and found them to be viable but sterile in both sexes. Sterility is due to failure of both male and female germ cells to progress past the first meiotic metaphase. The chromosomal events up through the end of prophase I are normal in both CKS2-/- males and females, suggesting that the phenotype is due directly to failure to enter anaphase and not a consequence of a checkpoint-mediated metaphase I arrest.
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Affiliation(s)
- Charles H Spruck
- Department of Molecular Biology, MB-7, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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31
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Inui N, Kitagawa K, Miwa S, Hattori T, Chida K, Nakamura H, Kitagawa M. High expression of Cks1 in human non-small cell lung carcinomas. Biochem Biophys Res Commun 2003; 303:978-84. [PMID: 12670508 DOI: 10.1016/s0006-291x(03)00469-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Enhanced degradation of cyclin-dependent kinase (CDK) inhibitor p27(Kip1) is known to be a powerful prognostic marker in many types of human cancers. Human CDK subunit 1 (Cks1) and S-phase kinase associated protein 2 (Skp2) are components of the SCF(Skp2) complex, which acts as a ubiquitin ligase for p27(Kip1). There are no reports about the involvement of Cks1 in the pathogenesis of human cancer. Here we show high expression of Cks1 in non-small cell lung cancers (NSCLCs) using Western blotting and quantitative real-time RT-PCR. The Skp2 mRNA expression level was high in squamous cell carcinomas and was inversely related with the p27(Kip1) protein level in individual clinical samples. In contrast, Cks1 mRNA expression had no such relationship with p27(Kip1), although Cks1 mRNA was significantly elevated in adenocarcinomas. These results suggest that high expression of Skp2 and Cks1 may be involved in the pathogenesis of NSCLCs via different mechanisms.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Adenocarcinoma/etiology
- Adenocarcinoma/genetics
- Adenocarcinoma/metabolism
- Adult
- Aged
- Aged, 80 and over
- Base Sequence
- Carcinoma, Non-Small-Cell Lung/etiology
- Carcinoma, Non-Small-Cell Lung/genetics
- Carcinoma, Non-Small-Cell Lung/metabolism
- Carcinoma, Squamous Cell/etiology
- Carcinoma, Squamous Cell/genetics
- Carcinoma, Squamous Cell/metabolism
- Cell Cycle Proteins/genetics
- Cell Cycle Proteins/metabolism
- Cyclin-Dependent Kinase Inhibitor p27
- Female
- Gene Expression
- Humans
- Immunohistochemistry
- Lung Neoplasms/etiology
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Male
- Middle Aged
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Neoplasm/genetics
- RNA, Neoplasm/metabolism
- S-Phase Kinase-Associated Proteins
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Tumor Suppressor Proteins/genetics
- Tumor Suppressor Proteins/metabolism
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Affiliation(s)
- Naoki Inui
- Second Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan
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32
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Vogel L, Baratte B, Détivaud L, Azzi L, Leopold P, Meijer L. Molecular cloning and characterisation of p15(CDK-BP), a novel CDK-binding protein. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1589:219-31. [PMID: 12007796 DOI: 10.1016/s0167-4889(02)00175-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The suc1/Cks proteins are well-conserved regulatory components of cyclin-dependent kinases 1 and 2 (CDK1/2). These small molecular mass proteins form a stable complex with CDK1/2 and are essential for normal regulation of CDKs during the cell division cycle and for degradation of p27(kip1). Despite the high degree of homology between the nine known CDKs, only CDK1, CDK2 and, to a lesser extent, CDK3 are able to bind to the suc1/Cks proteins. No additional suc1/Cks-related proteins interacting with other CDKs have been reported. We have purified, from starfish oocytes, a 15 kDa protein, p15(CDK-BP), which cross-reacts with anti-Cks antibodies (L. Azzi, L. Meijer, A.C. Ostvold, J. Lew, J.H. Wang, J. Biol. Chem. 269 (1994)). Following microsequencing of internal peptides and generation of corresponding oligonucleotides we cloned two cDNAs encoding two closely related proteins, p15A and p15B. The predicted protein sequences display distant but distinct homology with the Suc1/Cks proteins, including the genuine starfish Cks homologue protein, p9(CksMg). P15 transcripts are essentially expressed in oocytes. Recombinant p15B or native p15(CDK-BP) bind a 34 kDa protein cross-reacting with anti-PSTAIRE antibodies, a feature characteristic of CDK-related proteins. In addition p15B interacts tightly with CDK4, CDK6, CDK8 and the yeast CDC28-related kinase Pho85, but not with CDK1, CDK2 or CDK7. P15 does not appear to alter the catalytic activity of the bound kinases.
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Affiliation(s)
- Lee Vogel
- CNRS, Station Biologique, Roscoff, Bretagne, France
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33
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Affiliation(s)
- J W Harper
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
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34
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Abstract
Cks1, a subunit of cyclin-dependent kinases, has now been identified as an essential cofactor in the ubiquitination of the Cdk inhibitor p27 by the SCF(Skp2) ubiquitin ligase. This activity, which can be independent of Cdk binding, links Cks to positive growth control pathways regulating the G1/S transition and to cancer.
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Affiliation(s)
- J W Harper
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
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35
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Spruck C, Strohmaier H, Watson M, Smith AP, Ryan A, Krek TW, Reed SI. A CDK-independent function of mammalian Cks1: targeting of SCF(Skp2) to the CDK inhibitor p27Kip1. Mol Cell 2001; 7:639-50. [PMID: 11463388 DOI: 10.1016/s1097-2765(01)00210-6] [Citation(s) in RCA: 298] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Cks/Suc1 proteins associate with CDK/cyclin complexes, but their precise function(s) is not well defined. Here we demonstrate that Cks1 directs the ubiquitin-mediated proteolysis of the CDK-bound substrate p27Kip1 by the protein ubiquitin ligase (E3) SCF(Skp2). Cks1 associates with the F box protein Skp2 and is essential for recognition of the p27Kip1 substrate for ubiquitination in vivo and in vitro. Using purified recombinant proteins, we reconstituted p27Kip1 ubiquitination activity and show that it is dependent on Cks1. CKS1-/- mice are abnormally small, and cells derived from them proliferate poorly, particularly under limiting mitogen conditions, possibly due to elevated levels of p27Kip1.
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Affiliation(s)
- C Spruck
- The Scripps Research Institute, La Jolla, California 92037, USA
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36
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Honey S, Schneider BL, Schieltz DM, Yates JR, Futcher B. A novel multiple affinity purification tag and its use in identification of proteins associated with a cyclin-CDK complex. Nucleic Acids Res 2001; 29:E24. [PMID: 11160944 PMCID: PMC29631 DOI: 10.1093/nar/29.4.e24] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2000] [Revised: 12/30/2000] [Accepted: 12/30/2000] [Indexed: 11/13/2022] Open
Abstract
A novel multiple affinity purification (MAFT) or tandem affinity purification (TAP) tag has been constructed. It consists of the calmodulin binding peptide, six histidine residues, and three copies of the hemagglutinin epitope. This 'CHH' MAFT tag allows two or three consecutive purification steps, giving high purity. Active Clb2-Cdc28 kinase complex was purified from yeast cells after inserting the CHH tag into Clb2. Associated proteins were identified using mass spectrometry. These included the known associated proteins Cdc28, Sic1 and Cks1. Several other proteins were found including the 70 kDa chaperone, Ssa1.
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Affiliation(s)
- S Honey
- Cold Spring Harbor Laboratories, Cold Spring Harbor, NY 11724, USA
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37
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Bellí G, Garí E, Aldea M, Herrero E. Osmotic stress causes a G1 cell cycle delay and downregulation of Cln3/Cdc28 activity in Saccharomyces cerevisiae. Mol Microbiol 2001; 39:1022-35. [PMID: 11251821 DOI: 10.1046/j.1365-2958.2001.02297.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Moderate hyperosmotic stress on Saccharomyces cerevisiae cells produces a temporary delay at the G1 stage of the cell cycle. This is accompanied by transitory downregulation of CLN1, CLN2 and CLB5 transcript levels, although not of CLN3, which codes for the most upstream activator of the G1/S transition. Osmotic shock to cells synchronized in early G1, when Cln3 is the only cyclin present, causes a delay in cell cycle resumption. This points to Cln3 as being a key cell cycle target for osmotic stress. We have observed that osmotic shock causes downregulation of the kinase activity of Cln3-Cdc28 complexes. This is concomitant with a temporary accumulation of Cln3 protein as a result of increased stability. The effects of the osmotic stress in G1 are not suppressed in CLN3-1 cells with increased kinase activity, as the Cln3-Cdc28 activity in this mutant is still affected by the shock. Although Hog1 is not required for the observed cell cycle arrest in hyperosmotic conditions, it is necessary to resume the cell cycle at KCl concentrations higher than 0.4 M.
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Affiliation(s)
- G Bellí
- Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida, Rovira Roure 44, 25198 Lleida, Spain
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38
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Jensen S, Segal M, Clarke DJ, Reed SI. A novel role of the budding yeast separin Esp1 in anaphase spindle elongation: evidence that proper spindle association of Esp1 is regulated by Pds1. J Cell Biol 2001; 152:27-40. [PMID: 11149918 PMCID: PMC2193664 DOI: 10.1083/jcb.152.1.27] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In Saccharomyces cerevisiae, the metaphase-anaphase transition is initiated by the anaphase-promoting complex-dependent degradation of Pds1, whereby Esp1 is activated to promote sister chromatid separation. Although this is a fundamental step in the cell cycle, little is known about the regulation of Esp1 and how loss of cohesion is coordinated with movement of the anaphase spindle. Here, we show that Esp1 has a novel role in promoting anaphase spindle elongation. The localization of Esp1 to the spindle apparatus, analyzed by live cell imaging, is regulated in a manner consistent with a function during anaphase B. The protein accumulates in the nucleus in G2 and is mobilized onto the spindle pole bodies and spindle midzone at anaphase onset, where it persists into midanaphase. Association with Pds1 occurs during S phase and is required for efficient nuclear targeting of Esp1. Spindle association is not fully restored in pds1 mutants expressing an Esp1-nuclear localization sequence fusion protein, suggesting that Pds1 is also required to promote Esp1 spindle binding. In agreement, Pds1 interacts with the spindle at the metaphase-anaphase transition and a fraction remains at the spindle pole bodies and the spindle midzone in anaphase cells. Finally, mutational analysis reveals that the conserved COOH-terminal region of Esp1 is important for spindle interaction.
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Affiliation(s)
- Sanne Jensen
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Marisa Segal
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Duncan J. Clarke
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Steven I. Reed
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037
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39
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Mongay L, Plaza S, Vigorito E, Serra-Pagès C, Vives J. Association of the Cell Cycle Regulatory Proteins p45SKP2 and CksHs1. J Biol Chem 2001; 276:25030-6. [PMID: 11349131 DOI: 10.1074/jbc.m102184200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In mammalian cells, CDK2 is part of a multiprotein complex that includes Cyclin A or E and cell cycle regulatory proteins such as p21(Cip1), PCNA, p27(Kip1), p45(SKP2), p19(SKP1), and CksHs1/CksHs2. While the role of some of these proteins has been well studied, the function of other proteins in the complex remains unclear. In this study, we showed that the carboxyl-terminal region of p45(SKP2) associates directly with CksHs1 and that CksHs1 negatively regulated the interaction between p45(SKP2) and CDK2. Moreover, we showed that overexpression of CksHs1 inhibits CDK2 kinase activity and that additional expression of p45(SKP2) overcame this inhibition and restored CDK2 kinase activity. We proposed that the association of CksHs1 and p45(SKP2) prevented CksHs1 from binding CDK2 and negatively regulating the CDK2 kinase activity.
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Affiliation(s)
- L Mongay
- Servei d'Immunologia, Hospital Clínic i Provincial de Barcelona, Villarroel 170, Barcelona 08036, Spain
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40
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Bourne Y, Watson MH, Arvai AS, Bernstein SL, Reed SI, Tainer JA. Crystal structure and mutational analysis of the Saccharomyces cerevisiae cell cycle regulatory protein Cks1: implications for domain swapping, anion binding and protein interactions. Structure 2000; 8:841-50. [PMID: 10997903 DOI: 10.1016/s0969-2126(00)00175-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND The Saccharomyces cerevisiae protein Cks1 (cyclin-dependent kinase subunit 1) is essential for cell-cycle progression. The biological function of Cks1 can be modulated by a switch between two distinct molecular assemblies: the single domain fold, which results from the closing of a beta-hinge motif, and the intersubunit beta-strand interchanged dimer, which arises from the opening of the beta-hinge motif. The crystal structure of a cyclin-dependent kinase (Cdk) in complex with the human Cks homolog CksHs1 single-domain fold revealed the importance of conserved hydrophobic residues and charged residues within the beta-hinge motif. RESULTS The 3.0 A resolution Cks1 structure reveals the strict structural conservation of the Cks alpha/beta-core fold and the beta-hinge motif. The beta hinge identified in the Cks1 structure includes a novel pivot and exposes a cluster of conserved tyrosine residues that are involved in Cdk binding but are sequestered in the beta-interchanged Cks homolog suc1 dimer structure. This Cks1 structure confirms the conservation of the Cks anion-binding site, which interacts with sidechain residues from the C-terminal alpha helix of another subunit in the crystal. CONCLUSIONS The Cks1 structure exemplifies the conservation of the beta-interchanged dimer and the anion-binding site in evolutionarily distant yeast and human Cks homologs. Mutational analyses including in vivo rescue of CKS1 disruption support the dual functional roles of the beta-hinge residue Glu94, which participates in Cdk binding, and of the anion-binding pocket that is located 22 A away and on an opposite face to Glu94. The Cks1 structure suggests a biological role for the beta-interchanged dimer and the anion-binding site in targeting Cdks to specific phosphoproteins during cell-cycle progression.
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Affiliation(s)
- Y Bourne
- Centre National de la Recherche Scientifique, Marseille, France.
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41
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Reynard GJ, Reynolds W, Verma R, Deshaies RJ. Cks1 is required for G(1) cyclin-cyclin-dependent kinase activity in budding yeast. Mol Cell Biol 2000; 20:5858-64. [PMID: 10913169 PMCID: PMC86063 DOI: 10.1128/mcb.20.16.5858-5864.2000] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
p13(suc1) (Cks) proteins have been implicated in the regulation of cyclin-dependent kinase (CDK) activity. However, the mechanism by which Cks influences the function of cyclin-CDK complexes has remained elusive. We show here that Cks1 is required for the protein kinase activity of budding yeast G(1) cyclin-CDK complexes. Cln2 and Cdc28 subunits coexpressed in baculovirus-infected insect cells fail to exhibit protein kinase activity towards multiple substrates in the absence of Cks1. Cks1 can both stabilize Cln2-Cdc28 complexes and activate intact complexes in vitro, suggesting that it plays multiple roles in the biogenesis of active G(1) cyclin-CDK complexes. In contrast, Cdc28 forms stable, active complexes with the B-type cyclins Clb4 and Clb5 regardless of whether Cks1 is present. The levels of Cln2-Cdc28 and Cln3-Cdc28 protein kinase activity are severely reduced in cks1-38 cell extracts. Moreover, phosphorylation of G(1) cyclins, which depends on Cdc28 activity, is reduced in cks1-38 cells. The role of Cks1 in promoting G(1) cyclin-CDK protein kinase activity both in vitro and in vivo provides a simple molecular rationale for the essential role of CKS1 in progression through G(1) phase in budding yeast.
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Affiliation(s)
- G J Reynard
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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42
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Rudner AD, Hardwick KG, Murray AW. Cdc28 activates exit from mitosis in budding yeast. J Cell Biol 2000; 149:1361-76. [PMID: 10871278 PMCID: PMC2175138 DOI: 10.1083/jcb.149.7.1361] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2000] [Accepted: 05/17/2000] [Indexed: 11/30/2022] Open
Abstract
The activity of the cyclin-dependent kinase 1 (Cdk1), Cdc28, inhibits the transition from anaphase to G1 in budding yeast. CDC28-T18V, Y19F (CDC28-VF), a mutant that lacks inhibitory phosphorylation sites, delays the exit from mitosis and is hypersensitive to perturbations that arrest cells in mitosis. Surprisingly, this behavior is not due to a lack of inhibitory phosphorylation or increased kinase activity, but reflects reduced activity of the anaphase-promoting complex (APC), a defect shared with other mutants that lower Cdc28/Clb activity in mitosis. CDC28-VF has reduced Cdc20- dependent APC activity in mitosis, but normal Hct1- dependent APC activity in the G1 phase of the cell cycle. The defect in Cdc20-dependent APC activity in CDC28-VF correlates with reduced association of Cdc20 with the APC. The defects of CDC28-VF suggest that Cdc28 activity is required to induce the metaphase to anaphase transition and initiate the transition from anaphase to G1 in budding yeast.
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Affiliation(s)
- Adam D. Rudner
- Department of Physiology, University of California, San Francisco, California 94143-0444
- Department of Biochemistry, University of California, San Francisco, California 94143-0444
| | - Kevin G. Hardwick
- Department of Physiology, University of California, San Francisco, California 94143-0444
| | - Andrew W. Murray
- Department of Physiology, University of California, San Francisco, California 94143-0444
- Department of Biochemistry, University of California, San Francisco, California 94143-0444
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43
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Rudner AD, Murray AW. Phosphorylation by Cdc28 activates the Cdc20-dependent activity of the anaphase-promoting complex. J Cell Biol 2000; 149:1377-90. [PMID: 10871279 PMCID: PMC2175139 DOI: 10.1083/jcb.149.7.1377] [Citation(s) in RCA: 236] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Budding yeast initiates anaphase by activating the Cdc20-dependent anaphase-promoting complex (APC). The mitotic activity of Cdc28 (Cdk1) is required to activate this form of the APC, and mutants that are impaired in mitotic Cdc28 function have difficulty leaving mitosis. This defect can be explained by a defect in APC phosphorylation, which depends on mitotic Cdc28 activity in vivo and can be catalyzed by purified Cdc28 in vitro. Mutating putative Cdc28 phosphorylation sites in three components of the APC, Cdc16, Cdc23, and Cdc27, makes the APC resistant to phosphorylation both in vivo and in vitro. The nonphosphorylatable APC has normal activity in G1, but its mitotic, Cdc20-dependent activity is compromised. These results show that Cdc28 activates the APC in budding yeast to trigger anaphase. Previous reports have shown that the budding yeast Cdc5 homologue, Plk, can also phosphorylate and activate the APC in vitro. We show that, like cdc28 mutants, cdc5 mutants affect APC phosphorylation in vivo. However, although Cdc5 can phosphorylate Cdc16 and Cdc27 in vitro, this in vitro phosphorylation does not occur on in vivo sites of phosphorylation.
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Affiliation(s)
- Adam D. Rudner
- Department of Physiology, University of California, San Francisco, California 94143-0444
- Department of Biochemistry, University of California, San Francisco, California 94143-0444
| | - Andrew W. Murray
- Department of Physiology, University of California, San Francisco, California 94143-0444
- Department of Biochemistry, University of California, San Francisco, California 94143-0444
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44
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Ross KE, Kaldis P, Solomon MJ. Activating phosphorylation of the Saccharomyces cerevisiae cyclin-dependent kinase, cdc28p, precedes cyclin binding. Mol Biol Cell 2000; 11:1597-609. [PMID: 10793138 PMCID: PMC14870 DOI: 10.1091/mbc.11.5.1597] [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: 11/11/2022] Open
Abstract
Eukaryotic cell cycle progression is controlled by a family of protein kinases known as cyclin-dependent kinases (Cdks). Two steps are essential for Cdk activation: binding of a cyclin and phosphorylation on a conserved threonine residue by the Cdk-activating kinase (CAK). We have studied the interplay between these regulatory mechanisms during the activation of the major Saccharomyces cerevisiae Cdk, Cdc28p. We found that the majority of Cdc28p was phosphorylated on its activating threonine (Thr-169) throughout the cell cycle. The extent of Thr-169 phosphorylation was similar for monomeric Cdc28p and Cdc28p bound to cyclin. By varying the order of the addition of cyclin and Cak1p, we determined that Cdc28p was activated most efficiently when it was phosphorylated before cyclin binding. Furthermore, we found that a Cdc28p(T169A) mutant, which cannot be phosphorylated, bound cyclin less well than wild-type Cdc28p in vivo. These results suggest that unphosphorylated Cdc28p may be unable to bind tightly to cyclin. We propose that Cdc28p is normally phosphorylated by Cak1p before it binds cyclin. This activation pathway contrasts with that in higher eukaryotes, in which cyclin binding appears to precede activating phosphorylation.
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Affiliation(s)
- K E Ross
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-2114, USA
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45
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Patra D, Wang SX, Kumagai A, Dunphy WG. The xenopus Suc1/Cks protein promotes the phosphorylation of G(2)/M regulators. J Biol Chem 1999; 274:36839-42. [PMID: 10601234 DOI: 10.1074/jbc.274.52.36839] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The entry into mitosis is controlled by Cdc2/cyclin B, also known as maturation or M-phase promoting factor (MPF). In Xenopus egg extracts, the inhibitory phosphorylations of Cdc2 on Tyr-15 and Thr-14 are controlled by the phosphatase Cdc25 and the kinases Myt1 and Wee1. At mitosis, Cdc25 is activated and Myt1 and Wee1 are inactivated through phosphorylation by multiple kinases, including Cdc2 itself. The Cdc2-associated Suc1/Cks1 protein (p9) is also essential for entry of egg extracts into mitosis, but the molecular basis of this requirement has been unknown. We find that p9 strongly stimulates the regulatory phosphorylations of Cdc25, Myt1, and Wee1 that are carried out by the Cdc2/cyclin B complex. Overexpression of the prolyl isomerase Pin1, which binds to the hyperphosphorylated forms of Cdc25, Myt1, and Wee1 found at M-phase, is known to block the initiation of mitosis in egg extracts. We have observed that Pin1 specifically antagonizes the stimulatory effect of p9 on phosphorylation of Cdc25 by Cdc2/cyclin B. This observation could explain why overexpression of Pin1 inhibits mitotic initiation. These findings suggest that p9 promotes the entry into mitosis by facilitating phosphorylation of the key upstream regulators of Cdc2.
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Affiliation(s)
- D Patra
- Division of Biology 216-76, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125, USA
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46
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Bailly E, Reed SI. Functional characterization of rpn3 uncovers a distinct 19S proteasomal subunit requirement for ubiquitin-dependent proteolysis of cell cycle regulatory proteins in budding yeast. Mol Cell Biol 1999; 19:6872-90. [PMID: 10490625 PMCID: PMC84683 DOI: 10.1128/mcb.19.10.6872] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By selectively eliminating ubiquitin-conjugated proteins, the 26S proteasome plays a pivotal role in a large variety of cellular regulatory processes, particularly in the control of cell cycle transitions. Access of ubiquitinated substrates to the inner catalytic chamber within the 20S core particle is mediated by the 19S regulatory particle (RP), whose subunit composition in budding yeast has been recently elucidated. In this study, we have investigated the cell cycle defects resulting from conditional inactivation of one of these RP components, the essential non-ATPase Rpn3/Sun2 subunit. Using temperature-sensitive mutant alleles, we show that rpn3 mutations do not prevent the G(1)/S transition but cause a metaphase arrest, indicating that the essential Rpn3 function is limiting for mitosis. rpn3 mutants appear severely compromised in the ubiquitin-dependent proteolysis of several physiologically important proteasome substrates. Thus, RPN3 function is required for the degradation of the G(1)-phase cyclin Cln2 targeted by SCF; the S-phase cyclin Clb5, whose ubiquitination is likely to involve a combination of E3 (ubiquitin protein ligase) enzymes; and anaphase-promoting complex targets, such as the B-type cyclin Clb2 and the anaphase inhibitor Pds1. Our results indicate that the Pds1 degradation defect of the rpn3 mutants most likely accounts for the metaphase arrest phenotype observed. Surprisingly, but consistent with the lack of a G(1) arrest phenotype in thermosensitive rpn3 strains, the Cdk inhibitor Sic1 exhibits a short half-life regardless of the RPN3 genotype. In striking contrast, Sic1 turnover is severely impaired by a temperature-sensitive mutation in RPN12/NIN1, encoding another essential RP subunit. While other interpretations are possible, these data strongly argue for the requirement of distinct RP subunits for efficient proteolysis of specific cell cycle regulators. The potential implications of these data are discussed in the context of possible Rpn3 function in multiubiquitin-protein conjugate recognition by the 19S proteasomal regulatory particle.
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Affiliation(s)
- E Bailly
- Institut Curie-UMR 144, 75248 Paris Cedex 05, France.
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47
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Détivaud L, Pettit GR, Meijer L. Characterization of a novel cdk1-related kinase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:55-66. [PMID: 10447673 DOI: 10.1046/j.1432-1327.1999.00576.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The p13suc1/p9CKShs proteins bind tightly to the cyclin-dependent kinases cdk1 and cdk2. The distantly related protein, p15cdk-BP, binds cdk4/6, cdk5 and cdk8. We now show that immobilized p15cdk-BP binds both an HMG-I kinase and a 35-kDa protein that cross-reacts with anti-PSTAIRE antibodies (PSTAIRE is a totally conserved motif located in subdomain III of cdk). This 'cdkX' and the HMG-I kinase also bind to an immobilized inhibitor of cdks (HD). Several properties clearly distinguish cdkX, and its associated HMG-I kinase, from known anti-PSTAIRE cross-reactive cdks: (a) cdkX migrates, in SDS/PAGE, in a position intermediate between prophase phosphorylated cdk1 and metaphase dephosphorylated cdk1; (b) in contrast with cdk1, cdkX and associated HMG-I kinase activity do not decrease following successive depletions on p9CKShs1-sepharose; (c) cdkX and associated HMG-I kinase activity, but not cdk1, decrease following depletions on immobilized inhibitor; (d) cdkX is expressed during the early development of sea urchin embryos; in contrast with cdk1/cyclin B kinase, the p15cdk-BP-bound HMG-I kinase is active throughout the cell cycle; compared with cdk1 it is active later in development; (e) p15cdk-BP-bound HMG-I kinase is essentially insensitive to powerful inhibitors of cdk such as purvalanol, roscovitine, olomoucine, p21cip1 and p16INK4A; HD is only moderately inhibitory. Altogether these results suggest the existence of a new cdk1-related kinase, possibly involved in the regulation of early development. The presence of this kinase in all organisms investigated so far, from plants to mammals, calls for its definitive identification.
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Affiliation(s)
- L Détivaud
- CNRS, Station Biologique, Roscoff, France
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48
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Urbanowicz-Kachnowicz I, Baghdassarian N, Nakache C, Gracia D, Mekki Y, Bryon PA, Ffrench M. ckshs expression is linked to cell proliferation in normal and malignant human lymphoid cells. Int J Cancer 1999; 82:98-104. [PMID: 10360827 DOI: 10.1002/(sici)1097-0215(19990702)82:1<98::aid-ijc17>3.0.co;2-a] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cyclin kinase sub-units (CKS) are known to interact with cyclin-dependent kinases (CDKs), but their functions are not completely understood and their expression in human tissues is not documented. For analyzing relationships of CKS with cell proliferation and/or with differentiation, we investigated the expression of ckshs1 and ckshs2 in normal and malignant human lymphoid cells. ckshs1 and ckshs2 expression appeared to be related to cell proliferation: (i) mRNAs increased with stimulation of normal peripheral-blood lymphocytes, and from the G1 to the SG2M phase in elutriated cells; (ii) P9 proteins were also induced by lymphocyte stimulation and were localized in nucleus where phosphorylated forms of CDK1 were also found; (iii) in vitro, the phosphorylated forms of CDK1 and CDK2 were preferentially linked to CKS. Among 45 patients presenting acute or chronic lymphoid malignancy, ckshs1 and ckshs2 mRNAs varied in a similar way and were significantly correlated to cell proliferation (p < 0.0001). When analysis was restricted solely to acute lymphoblastic leukemia (ALL) this correlation was still found and ckshs1 and ckshs2 were significantly more expressed in T-cell ALL than in B-cell-lineage ALL. These results confirm relationships between ckshs expression and cell proliferation, and pose the question of a link with cell differentiation.
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49
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Bilodeau M, Talarmin H, Ilyin G, Rescan C, Glaise D, Cariou S, Loyer P, Guguen-Guillouzo C, Baffet G. Skp2 induction and phosphorylation is associated with the late G1 phase of proliferating rat hepatocytes. FEBS Lett 1999; 452:247-53. [PMID: 10386600 DOI: 10.1016/s0014-5793(99)00629-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The changes in phosphoproteins purified with the affinity peptide p9CKShs1 were analyzed from extracts of regenerating rat livers in order to define some G1 and G1/S regulations characteristic of mature hepatocytes stimulated to proliferate. We observed a 47 kDa phosphoprotein that occurred first at the end of G1 before peaking in the S phase. P47 was also found to be phosphorylated in late G1 in primary hepatocyte cultures stimulated with mitogens. P47 was still phosphorylated in extracts depleted of Cdc2, but to a lesser extent after Cdk2 depletion. This phosphoprotein was identified as Skp2. (i) P47 shared the same electrophoretic mobility than Skp2, a cell cycle protein essential for S phase entry in human fibroblasts; (ii) Skp2, like P47, started to be expressed and was highly phosphorylated during the G1/S transition of hepatocytes stimulated to proliferate in vivo and in vitro; (iii) P47 was specifically immunoprecipitated by an antibody directed against Skp2. In addition, cyclin A/Cdk2 complexes from regenerating liver clearly interacted with Skp2. This is the first demonstration that Skp2 is induced and phosphorylated in the late G1 and S phase of hepatocytes in vivo in regenerating liver as well as in vitro in mitogen-stimulated hepatocytes.
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Affiliation(s)
- M Bilodeau
- INSERM U49, Unité de Recherches Hépatologiques, Hôpital Pontchaillou, Rennes, France
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50
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Kaiser P, Moncollin V, Clarke DJ, Watson MH, Bertolaet BL, Reed SI, Bailly E. Cyclin-dependent kinase and Cks/Suc1 interact with the proteasome in yeast to control proteolysis of M-phase targets. Genes Dev 1999; 13:1190-202. [PMID: 10323869 PMCID: PMC316943 DOI: 10.1101/gad.13.9.1190] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cell cycle-specific proteolysis is critical for proper execution of mitosis in all eukaryotes. Ubiquitination and subsequent proteolysis of the mitotic regulators Clb2 and Pds1 depend on the cyclosome/APC and the 26S proteasome. We report here that components of the cell cycle machinery in yeast, specifically the cell cycle regulatory cyclin-dependent kinase Cdc28 and a conserved associated protein Cks1/Suc1, interact genetically, physically, and functionally with components of the 26S proteasome. A mutation in Cdc28 (cdc28-1N) that interferes with Cks1 binding, or inactivation of Cks1 itself, confers stabilization of Clb2, the principal mitotic B-type cyclin in budding yeast. Surprisingly, Clb2-ubiquitination in vivo and in vitro is not affected by mutations in cks1, indicating that Cks1 is not essential for cyclosome/APC activity. However, mutant Cks1 proteins no longer physically interact with the proteasome, suggesting that Cks1 is required for some aspect of proteasome function during M-phase-specific proteolysis. We further provide evidence that Cks1 function is required for degradation of the anaphase inhibitor Pds1. Stabilization of Pds1 is partially responsible for the metaphase arrest phenotype of cks1 mutants because deletion of PDS1 partially relieves the metaphase block in these mutants.
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Affiliation(s)
- P Kaiser
- The Scripps Research Institute, MB7, La Jolla, California 92037, USA
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