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Schatten H. The Impact of Centrosome Pathologies on Ovarian Cancer Development and Progression with a Focus on Centrosomes as Therapeutic Target. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1452:37-64. [PMID: 38805124 DOI: 10.1007/978-3-031-58311-7_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
The impact of centrosome abnormalities on cancer cell proliferation has been recognized as early as 1914 (Boveri, Zur Frage der Entstehung maligner Tumoren. Jena: G. Fisher, 1914), but vigorous research on molecular levels has only recently started when it became fully apparent that centrosomes can be targeted for new cancer therapies. While best known for their microtubule-organizing capabilities as MTOC (microtubule organizing center) in interphase and mitosis, centrosomes are now further well known for a variety of different functions, some of which are related to microtubule organization and consequential activities such as cell division, migration, maintenance of cell shape, and vesicle transport powered by motor proteins, while other functions include essential roles in cell cycle regulation, metabolic activities, signal transduction, proteolytic activity, and several others that are now heavily being investigated for their role in diseases and disorders (reviewed in Schatten and Sun, Histochem Cell Biol 150:303-325, 2018; Schatten, Adv Anat Embryol Cell Biol 235:43-50, 2022a; Schatten, Adv Anat Embryol Cell Biol 235:17-35, 2022b).Cancer cell centrosomes differ from centrosomes in noncancer cells in displaying specific abnormalities that include phosphorylation abnormalities, overexpression of specific centrosomal proteins, abnormalities in centriole and centrosome duplication, formation of multipolar spindles that play a role in aneuploidy and genomic instability, and several others that are highlighted in the present review on ovarian cancer. Ovarian cancer cell centrosomes, like those in other cancers, display complex abnormalities that in part are based on the heterogeneity of cells in the cancer tissues resulting from different etiologies of individual cancer cells that will be discussed in more detail in this chapter.Because of the critical role of centrosomes in cancer cell proliferation, several lines of research are being pursued to target centrosomes for therapeutic intervention to inhibit abnormal cancer cell proliferation and control tumor progression. Specific centrosome abnormalities observed in ovarian cancer will be addressed in this chapter with a focus on targeting such aberrations for ovarian cancer-specific therapies.
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Affiliation(s)
- Heide Schatten
- University of Missouri-Columbia Department of Veterinary Pathobiology, Columbia, MO, USA.
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2
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Thompson LL, Rutherford KA, Lepage CC, McManus KJ. Aberrant SKP1 Expression: Diverse Mechanisms Impacting Genome and Chromosome Stability. Front Cell Dev Biol 2022; 10:859582. [PMID: 35345853 PMCID: PMC8957228 DOI: 10.3389/fcell.2022.859582] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 02/22/2022] [Indexed: 11/26/2022] Open
Abstract
The S-phase Kinase-Associated Protein 1 (SKP1) is a core component of the SKP1, Cullin 1, F-box protein (SCF) complex, an E3 ubiquitin ligase that serves to poly-ubiquitinate a vast array of protein targets as a signal for their proteasomal degradation, thereby playing a critical role in the regulation of downstream biological processes. Many of the proteins regulated by SKP1 and the SCF complex normally function within pathways that are essential for maintaining genome stability, including DNA damage repair, apoptotic signaling, and centrosome dynamics. Accordingly, aberrant SKP1 and SCF complex expression and function is expected to disrupt these essential pathways, which may have pathological implications in diseases like cancer. In this review, we summarize the central role SKP1 plays in regulating essential cellular processes; we describe functional models in which SKP1 expression is altered and the corresponding impacts on genome stability; and we discuss the prevalence of SKP1 somatic copy number alterations, mutations, and altered protein expression across different cancer types, to identify a potential link between SKP1 and SCF complex dysfunction to chromosome/genome instability and cancer pathogenesis. Ultimately, understanding the role of SKP1 in driving chromosome instability will expand upon our rudimentary understanding of the key events required for genome/chromosome stability that may aid in our understanding of cancer pathogenesis, which will be critical for future studies to establish whether SKP1 may be useful as prognostic indicator or as a therapeutic target.
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Affiliation(s)
- Laura L Thompson
- CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
| | - Kailee A Rutherford
- CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
| | - Chloe C Lepage
- CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
| | - Kirk J McManus
- CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
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3
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Tian Z, He W, Tang J, Liao X, Yang Q, Wu Y, Wu G. Identification of Important Modules and Biomarkers in Breast Cancer Based on WGCNA. Onco Targets Ther 2020; 13:6805-6817. [PMID: 32764968 PMCID: PMC7367932 DOI: 10.2147/ott.s258439] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/17/2020] [Indexed: 12/12/2022] Open
Abstract
Introduction Breast cancer (BRCA) has the highest incidence among female malignancies, and the prognosis for these patients remains poor. Materials and Methods In this study, core modules and central genes related to BRCA were identified through a weighted gene co-expression network analysis (WGCNA). Gene expression profiles and clinical data of GSE25066 were obtained from the Gene Expression Omnibus (GEO) database. The result was validated with RNA-seq data from The Cancer Genome Atlas (TCGA) and Oncomine database. The top 30 key module genes with the highest intramodule connectivity were selected as the core genes (R2 = 0.40). Results According to TCGA and Oncomine datasets, seven genes were selected as candidate hub genes. Following further experimental verification, four hub genes (FAM171A1, NDFIP1, SKP1, and REEP5) were retained. Conclusion We identified four hub genes as candidate biomarkers for BRCA. These hub genes may provide a theoretical basis for targeted therapy against BRCA.
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Affiliation(s)
- Zelin Tian
- Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, People's Republic of China
| | - Weixiang He
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, People's Republic of China
| | - Jianing Tang
- Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, People's Republic of China
| | - Xing Liao
- Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, People's Republic of China
| | - Qian Yang
- Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, People's Republic of China
| | - Yumin Wu
- Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, People's Republic of China
| | - Gaosong Wu
- Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, People's Republic of China
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4
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King CR, A A Quadros AR, Chazeau A, Saarloos I, van der Graaf AJ, Verhage M, Toonen RF. Fbxo41 Promotes Disassembly of Neuronal Primary Cilia. Sci Rep 2019; 9:8179. [PMID: 31160656 PMCID: PMC6546786 DOI: 10.1038/s41598-019-44589-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/20/2019] [Indexed: 01/02/2023] Open
Abstract
Neuronal primary cilia are signaling organelles with crucial roles in brain development and disease. Cilia structure is decisive for their signaling capacities but the mechanisms regulating it are poorly understood. We identify Fbxo41 as a novel Skp1/Cullin1/F-box (SCF) E3-ligase complex subunit that targets to neuronal centrioles where its accumulation promotes disassembly of primary cilia, and affects sonic hedgehog signaling, a canonical ciliary pathway. Fbxo41 targeting to centrioles requires its Coiled-coil and F-box domains. Levels of Fbxo41 at the centrioles inversely correlate with neuronal cilia length, and mutations that disrupt Fbxo41 targeting or assembly into SCF-complexes also disturb its function in cilia disassembly and signaling. Fbxo41 dependent cilia disassembly in mitotic and post-mitotic cells requires rearrangements of the actin-cytoskeleton, but requires Aurora A kinase activation only in mitotic cells, highlighting important mechanistical differences controlling cilia size between mitotic and post-mitotic cells. Phorbol esters induce recruitment of overexpressed Fbxo41 to centrioles and cilia disassembly in neurons, but disassembly can also occur in absence of Fbxo41. We propose that Fbxo41 targeting to centrosomes regulates neuronal cilia structure and signaling capacity in addition to Fbxo41-independent pathways controlling cilia size.
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Affiliation(s)
- Cillian R King
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV, Amsterdam, The Netherlands
| | - Ana R A A Quadros
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV, Amsterdam, The Netherlands
| | - Anaël Chazeau
- Cell Biology, Faculty of Science, Utrecht University, 3584 CH, Utrecht, The Netherlands
| | - Ingrid Saarloos
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV, Amsterdam, The Netherlands.,Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV, Amsterdam, The Netherlands
| | - Anne Jolien van der Graaf
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV, Amsterdam, The Netherlands
| | - Matthijs Verhage
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV, Amsterdam, The Netherlands.,Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV, Amsterdam, The Netherlands
| | - Ruud F Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV, Amsterdam, The Netherlands.
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5
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Hussain M, Lu Y, Liu YQ, Su K, Zhang J, Liu J, Zhou GB. Skp1: Implications in cancer and SCF-oriented anti-cancer drug discovery. Pharmacol Res 2016; 111:34-42. [PMID: 27238229 DOI: 10.1016/j.phrs.2016.05.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 04/28/2016] [Accepted: 05/25/2016] [Indexed: 12/29/2022]
Abstract
In the last decade, the ubiquitin proteasome system (UPS), in general, and E3 ubiquitin ligases, in particular, have emerged as valid drug targets for the development of novel anti-cancer therapeutics. Cullin RING Ligases (CRLs), which can be classified into eight groups (CRL1-8) and comprise approximately 200 members, represent the largest family of E3 ubiquitin ligases which facilitate the ubiquitination-derived proteasomal degradation of a myriad of functionally and structurally diverse substrates. S phase kinase-associated protein 1 (Skp1)-Cullin1-F-Box protein (SCF) complexes are the best characterized among CRLs, which play crucial roles in numerous cellular processes and physiological dysfunctions, such as in cancer biology. Currently, there is growing interest in developing SCF-targeting anti-cancer therapies for clinical application. Indeed, the research in this field has seen some progress in the form of cullin neddylation- and Skp2-inhibitors. However, it still remains an underdeveloped area and needs to design new strategies for developing improved form of therapy. In this review, we venture a novel strategy that rational pharmacological targeting of Skp1, a central regulator of SCF complexes, may provide a novel avenue for SCF-oriented anti-cancer therapy, expected: (i) to simultaneously address the critical roles that multiple SCF oncogenic complexes play in cancer biology, (ii) to selectively target cancer cells with minimal normal cell toxicity, and (iii) to offer multiple chemical series, via therapeutic interventions at the Skp1 binding interfaces in SCF complex, thereby maximizing chances of success for drug discovery. In addition, we also discuss the challenges that might be posed regarding rational pharmacological interventions against Skp1.
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Affiliation(s)
- Muzammal Hussain
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou, 510530, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Yongzhi Lu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou, 510530, PR China
| | - Yong-Qiang Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China
| | - Kai Su
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou, 510530, PR China; School of Life Sciences, University of Science and Technology of China, Hefei, 230000, PR China
| | - Jiancun Zhang
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou, 510530, PR China; State Key Laboratory of Respiratory Disease, Guangzhou Medical University, Guangzhou, PR China
| | - Jinsong Liu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou, 510530, PR China.
| | - Guang-Biao Zhou
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China.
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6
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Thirunavukarasou A, Govindarajalu G, Singh P, Bandi V, Muthu K, Baluchamy S. Cullin 4A and 4B ubiquitin ligases interact with γ-tubulin and induce its polyubiquitination. Mol Cell Biochem 2014; 401:219-28. [DOI: 10.1007/s11010-014-2309-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Accepted: 12/20/2014] [Indexed: 11/27/2022]
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Schatten H, Sun QY. Posttranslationally modified tubulins and other cytoskeletal proteins: their role in gametogenesis, oocyte maturation, fertilization and Pre-implantation embryo development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 759:57-87. [PMID: 25030760 DOI: 10.1007/978-1-4939-0817-2_4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The cytoskeleton, mainly consisting of microtubules, intermediate filaments and microfilaments, along with cytoskeleton associated and interconnecting proteins as well as the centrosome, plays enormously important roles in all stages of embryogenesis and undergoes significant changes to accommodate a diversity of cellular functions during gametogenesis, oocyte maturation, fertilization and pre-implantation embryo development. The varied functions of the cytoskeleton can be accomplished on many different levels, among which are a diversity of different posttranslational modifications (PTMs), chemical modifications that regulate activity, localization and interactions with other cellular molecules. PTMs of the cytoskeleton, including phosphorylation, glycosylation, ubiquitination, detyrosination/tyrosination, (poly)glutamylation and (poly)glycylation, acetylation, sumoylation, and palmitoylation, will be addressed in this chapter. Focus will be on (1) Microtubules, microtubule organizing centers (centrosomes), intermediate filaments, microfilaments and their PTMs; (2) Cytoskeletal functions and cytoskeletal PTMs during gametogenesis and oocyte maturation; and (3) Cytoskeletal functions and cytoskeletal PTMs during fertilization and pre-implantation embryo development.
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Affiliation(s)
- Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri, 1600 E Rollins Street, Columbia, MO, 65211, USA,
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8
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Abstract
Polo-like kinase 4 (PLK4) is a unique member of the Polo-like family of kinases that shares little homology with its siblings and has an essential role in centriole duplication. The turn-over of this kinase must be strictly controlled to prevent centriole amplification. This is achieved, in part, by an autoregulatory mechanism, whereby PLK4 autophosphorylates residues in a PEST sequence located carboxy-terminal to its catalytic domain. Phosphorylated PLK4 is subsequently recognized by the SCF complex, ubiquitinylated and targeted to the proteasome for degradation. Recent data have also shown that active PLK4 is restricted to the centrosome, a mechanism that could serve to prevent aberrant centriole assembly elsewhere in the cell. While significant advances have been made in understanding how PLK4 is regulated it is certain that additional regulatory mechanisms exist to safeguard the fidelity of centriole duplication. Here, we overview past and present data discussing the regulation and functions of PLK4.
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9
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Korzeniewski N, Zheng L, Cuevas R, Parry J, Chatterjee P, Anderton B, Duensing A, Münger K, Duensing S. Cullin 1 functions as a centrosomal suppressor of centriole multiplication by regulating polo-like kinase 4 protein levels. Cancer Res 2009; 69:6668-75. [PMID: 19679553 DOI: 10.1158/0008-5472.can-09-1284] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abnormal centrosome and centriole numbers are frequently detected in tumor cells where they can contribute to mitotic aberrations that cause chromosome missegregation and aneuploidy. The molecular mechanisms of centriole overduplication in malignant cells, however, are poorly characterized. Here, we show that the core SKP1-cullin-F-box component cullin 1 (CUL1) localizes to maternal centrioles and that CUL1 is critical for suppressing centriole overduplication through multiplication, a recently discovered mechanism whereby multiple daughter centrioles form concurrently at single maternal centrioles. We found that this activity of CUL1 involves the degradation of Polo-like kinase 4 (PLK4) at maternal centrioles. PLK4 is required for centriole duplication and strongly stimulates centriole multiplication when aberrantly expressed. We found that CUL1 is critical for the degradation of active PLK4 following deregulation of cyclin E/cyclin-dependent kinase 2 activity, as is frequently observed in human cancer cells, as well as for baseline PLK4 protein stability. Collectively, our results suggest that CUL1 may function as a tumor suppressor by regulating PLK4 protein levels and thereby restraining excessive daughter centriole formation at maternal centrioles.
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10
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Lim HH, Zhang T, Surana U. Regulation of centrosome separation in yeast and vertebrates: common threads. Trends Cell Biol 2009; 19:325-33. [PMID: 19576775 DOI: 10.1016/j.tcb.2009.03.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 03/04/2009] [Accepted: 03/05/2009] [Indexed: 02/06/2023]
Abstract
The assembly of a bipolar spindle is crucial for symmetric partitioning of duplicated chromosomes during cell division. Centrosomes (spindle pole body [SPB] in yeast) constitute the two poles of this bipolar structure and serve as microtubule nucleation centers. A eukaryotic cell enters the division cycle with one centrosome and duplicates it before spindle formation. A proteinaceous link keeps duplicated centrosomes together until it is severed at onset of mitosis, enabling centrosomes to migrate away from each other and assemble a characteristic mitotic spindle. Hence, centrosome separation is crucial in assembly of a bipolar spindle. Whereas centrosome (or SPB) duplication has been characterized in some detail, the separation process is less well understood. Here, we review recent studies that uncover new players and provide a greater understanding of the regulation of centrosome (or SPB) separation.
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Affiliation(s)
- Hong Hwa Lim
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Proteos, 138673 Singapore
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11
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Abstract
Primarily known for its role as major microtubule organizing center, the centrosome is increasingly being recognized for its functional significance in key cell cycle regulating events. We are now at the beginning of understanding the centrosome’s functional complexities and its major impact on directing complex interactions and signal transduction cascades important for cell cycle regulation. The centrosome orchestrates entry into mitosis, anaphase onset, cytokinesis, G1/S transition, and monitors DNA damage. Recently, the centrosome has also been recognized as major docking station where regulatory complexes accumulate including kinases and phosphatases as well as numerous other cell cycle regulators that utilize the centrosome as platform to coordinate multiple cell cycle-specific functions. Vesicles that are translocated along microtubules to and away from centrosomes may also carry enzymes or substrates that use centrosomes as main docking station. The centrosome’s role in various diseases has been recognized and a wealth of data has been accumulated linking dysfunctional centrosomes to cancer, Alstrom syndrome, various neurological disorders, and others. Centrosome abnormalities and dysfunctions have been associated with several types of infertility. The present review highlights the centrosome’s significant roles in cell cycle events in somatic and reproductive cells and discusses centrosome abnormalities and implications in disease.
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Affiliation(s)
- Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri, 1600 E Rollins Street, Columbia, MO 65211, USA.
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12
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Hughes JR, Meireles AM, Fisher KH, Garcia A, Antrobus PR, Wainman A, Zitzmann N, Deane C, Ohkura H, Wakefield JG. A microtubule interactome: complexes with roles in cell cycle and mitosis. PLoS Biol 2008; 6:e98. [PMID: 18433294 PMCID: PMC2323305 DOI: 10.1371/journal.pbio.0060098] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Accepted: 03/07/2008] [Indexed: 01/19/2023] Open
Abstract
The microtubule (MT) cytoskeleton is required for many aspects of cell function, including the transport of intracellular materials, the maintenance of cell polarity, and the regulation of mitosis. These functions are coordinated by MT-associated proteins (MAPs), which work in concert with each other, binding MTs and altering their properties. We have used a MT cosedimentation assay, combined with 1D and 2D PAGE and mass spectrometry, to identify over 250 MAPs from early Drosophila embryos. We have taken two complementary approaches to analyse the cellular function of novel MAPs isolated using this approach. First, we have carried out an RNA interference (RNAi) screen, identifying 21 previously uncharacterised genes involved in MT organisation. Second, we have undertaken a bioinformatics analysis based on binary protein interaction data to produce putative interaction networks of MAPs. By combining both approaches, we have identified and validated MAP complexes with potentially important roles in cell cycle regulation and mitosis. This study therefore demonstrates that biologically relevant data can be harvested using such a multidisciplinary approach, and identifies new MAPs, many of which appear to be important in cell division.
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Affiliation(s)
- Julian R Hughes
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Ana M Meireles
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- Programa Doutoral em Biologia Experimental e Biomedicina, Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Katherine H Fisher
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Life Sciences Interface/Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Angel Garcia
- Department of Statistics, University of Oxford, Oxford, United Kingdom
| | - Philip R Antrobus
- Department of Statistics, University of Oxford, Oxford, United Kingdom
| | - Alan Wainman
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Nicole Zitzmann
- Department of Statistics, University of Oxford, Oxford, United Kingdom
| | - Charlotte Deane
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Hiroyuki Ohkura
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - James G Wakefield
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Life Sciences Interface/Doctoral Training Centre, University of Oxford, Oxford, United Kingdom
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13
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Duensing A, Liu Y, Perdreau SA, Kleylein-Sohn J, Nigg EA, Duensing S. Centriole overduplication through the concurrent formation of multiple daughter centrioles at single maternal templates. Oncogene 2007; 26:6280-8. [PMID: 17438528 PMCID: PMC2586811 DOI: 10.1038/sj.onc.1210456] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 02/28/2007] [Accepted: 03/01/2007] [Indexed: 12/22/2022]
Abstract
Abnormal centrosome numbers are detected in virtually all cancers. The molecular mechanisms that underlie centrosome amplification, however, are poorly characterized. Based on the model that each maternal centriole serves as a template for the formation of one and only one daughter centriole per cell division cycle, the prevailing view is that centriole overduplication arises from successive rounds of centriole reproduction. Here, we provide evidence that a single maternal centriole can concurrently generate multiple daughter centrioles. This mechanism was initially identified in cells treated with the peptide vinyl sulfone proteasome inhibitor Z-L(3)VS. We subsequently found that the formation of more than one daughter at maternal centrioles requires cyclin E/cyclin-dependent kinase 2 as well as Polo-like kinase 4 and that overexpression of these proteins mimics this phenotype in the absence of a proteasome inhibitor. Moreover, we show that the human papillomavirus type 16 E7 oncoprotein stimulates aberrant daughter centriole numbers in part through the formation of more than one daughter centriole at single maternal templates. These results help to explain how oncogenic stimuli can rapidly induce abnormal centriole numbers within a single cell-division cycle and provide insights into the regulation of centriole duplication.
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Affiliation(s)
- A Duensing
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
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Calderón-Villalobos LIA, Nill C, Marrocco K, Kretsch T, Schwechheimer C. The evolutionarily conserved Arabidopsis thaliana F-box protein AtFBP7 is required for efficient translation during temperature stress. Gene 2006; 392:106-16. [PMID: 17240087 DOI: 10.1016/j.gene.2006.11.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/12/2006] [Accepted: 11/20/2006] [Indexed: 11/30/2022]
Abstract
In eukaryotes, E3 ubiquitin ligases (E3s) mediate the ubiquitylation of proteins that are destined for degradation by the ubiquitin-proteasome system. In SKP1/CDC53/F-box protein (SCF)-type E3 complexes, the interchangeable F-box protein confers specificity to the E3 ligase through direct physical interactions with the degradation substrate. The vast majority of the approximately 700 F-box proteins from the plant model organism Arabidopsis thaliana remain to be characterized. Here, we investigate the previously uncharacterized and evolutionarily conserved Arabidopsis F-box protein 7 (AtFBP7), which is encoded by a unique gene in Arabidopsis (At1g21760). Several apparent fbp7 loss-of-function alleles do not have an obvious phenotype. AtFBP7 is ubiquitously expressed and its expression is induced after cold and heat stress. When following up on a reported co-purification of the eukaryotic elongation factor-2 (eEF-2) with YLR097c, the apparent budding yeast orthologue of AtFBP7, we discovered a general defect in protein biosynthesis after cold and heat stress in fbp7 mutants. Thus, our findings suggest that AtFBP7 is required for protein synthesis during temperature stress.
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Affiliation(s)
- Luz Irina A Calderón-Villalobos
- Department of Developmental Genetics, Centre for Plant Molecular Biology, Tübingen University, Auf der Morgenstelle 5, 72076 Tübingen, Germany
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15
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Jiang F, Caraway NP, Li R, Katz RL. RNA silencing of S-phase kinase-interacting protein 2 inhibits proliferation and centrosome amplification in lung cancer cells. Oncogene 2005; 24:3409-18. [PMID: 15735730 DOI: 10.1038/sj.onc.1208459] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The S-phase kinase-associated protein-2 (SKP2) plays a key role in ubiquitin-mediated proteolysis, which results in the progression of cells from a quiescence to proliferative state. SKP2 is overexpressed in a variety of tumors. In this study, we used small interfering RNAs (siRNAs) to inhibit the SKP2 expression in lung cancer cells and thereby investigate the role of SKP2 in lung tumorigenesis. Three lung cancer cell lines were transfected with siRNAs targeted against SKP2. SKP2-siRNAs specifically and efficiently reduced the levels of the SKP2 protein by 90% 48 h after transfection in all cell lines. In the A549 and H1792 cells, p27 expression was increased and the increase was inversely proportional to the level of SKP2; cell proliferation was reduced to 12 and 28%, respectively; apoptosis was increased to 36 and 30%, respectively; 36 and 28% of cells accumulated in the sub-G1 phase, respectively; and the population of cells in the G1 phase was decreased to 37 and 41%, respectively. In addition, the SKP2-depleted A549 and H1792 cells showed decreased levels of cyclin E/CDK2. Correspondingly, only 4 and 6% of the treated A549 and H1792 cells had multiple centrosomes, respectively, compared with 43 and 46% of the control cells, respectively. These results imply that SKP2 plays an oncogenic role in lung cancer and that SKP2 silencing may be useful in the treatment of lung cancer.
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Affiliation(s)
- Feng Jiang
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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16
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Blondel M, Bach S, Bamps S, Dobbelaere J, Wiget P, Longaretti C, Barral Y, Meijer L, Peter M. Degradation of Hof1 by SCF(Grr1) is important for actomyosin contraction during cytokinesis in yeast. EMBO J 2005; 24:1440-52. [PMID: 15775961 PMCID: PMC1142548 DOI: 10.1038/sj.emboj.7600627] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Accepted: 02/23/2005] [Indexed: 11/08/2022] Open
Abstract
SCF-type (SCF: Skp1-Cullin-F-box protein complex) E3 ligases regulate ubiquitin-dependent degradation of many cell cycle regulators, mainly at the G1/S transition. Here, we show that SCF(Grr1) functions during cytokinesis by degrading the PCH protein Hof1. While Hof1 is required early in mitosis to assemble a functional actomyosin ring, it is specifically degraded late in mitosis and remains unstable during the entire G1 phase of the cell cycle. Degradation of Hof1 depends on its PEST motif and a functional 26S proteasome. Interestingly, degradation of Hof1 is independent of APC(Cdh1), but instead requires the SCF(Grr1) E3 ligase. Grr1 is recruited to the mother-bud neck region after activation of the mitotic-exit network, and interacts with Hof1 in a PEST motif-dependent manner. Our results also show that downregulation of Hof1 at the end of mitosis is necessary to allow efficient contraction of the actomyosin ring and cell separation during cytokinesis. SCF(Grr1)-mediated degradation of Hof1 may thus represent a novel mechanism to couple exit from mitosis with initiation of cytokinesis.
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Affiliation(s)
- Marc Blondel
- CNRS, Station Biologique, UMR7150, Amyloids and Cell Division Cycle Laboratory, Place G Teissier, Roscoff, Bretagne, France.
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17
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Vuong BQ, Arenzana TL, Showalter BM, Losman J, Chen XP, Mostecki J, Banks AS, Limnander A, Fernandez N, Rothman PB. SOCS-1 localizes to the microtubule organizing complex-associated 20S proteasome. Mol Cell Biol 2004; 24:9092-101. [PMID: 15456882 PMCID: PMC517868 DOI: 10.1128/mcb.24.20.9092-9101.2004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2003] [Revised: 02/13/2004] [Accepted: 06/15/2004] [Indexed: 01/09/2023] Open
Abstract
The regulation of cytokine signaling is critical for controlling cellular proliferation and activation during an immune response. SOCS-1 is a potent inhibitor of Jak kinase activity and of signaling initiated by several cytokines. SOCS-1 protein levels are tightly regulated, and recent data suggest that SOCS-1 may regulate the protein levels of some signaling proteins by the ubiquitin proteasome pathway; however, the cellular mechanism by which SOCS-1 directs proteins for degradation is unknown. In this report, SOCS-1 is found to colocalize and biochemically copurify with the microtubule organizing complex (MTOC) and its associated 20S proteasome. The SOCS-1 SH2 domain is required for the localization of SOCS-1 to the MTOC. Overexpression of SOCS-1 targets Jak1 in an SH2-dependent manner to a perinuclear distribution resembling the MTOC-associated 20S proteasome. Analysis of MTOCs fractionated from SOCS-1-deficient cells demonstrates that SOCS-1 may function redundantly to regulate the localization of Jak1 to the MTOC. Nocodazole inhibits the protein turnover of SOCS-1, demonstrating that the minus-end transport of SOCS-1 to the MTOC-associated 20S proteasome is required to regulate SOCS-1 protein levels. These data link SOCS-1 directly with the proteasome pathway and suggest another function for the SH2 domain of SOCS-1 in the regulation of Jak/STAT signaling.
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Affiliation(s)
- Bao Q Vuong
- Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, USA [corrected]
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18
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Steensgaard P, Garrè M, Muradore I, Transidico P, Nigg EA, Kitagawa K, Earnshaw WC, Faretta M, Musacchio A. Sgt1 is required for human kinetochore assembly. EMBO Rep 2004; 5:626-31. [PMID: 15133482 PMCID: PMC1299074 DOI: 10.1038/sj.embor.7400154] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Revised: 03/11/2004] [Accepted: 03/31/2004] [Indexed: 11/09/2022] Open
Abstract
Budding yeast Sgt1 is required for kinetochore assembly, and its homologues have a role in cAMP signalling in fungi and pathogen resistance in plants. The function of mammalian Sgt1 is unknown. We report that RNA interference-mediated depletion of Sgt1 from HeLa cells causes dramatic alterations of the mitotic spindle and problems in chromosome alignment. Cells lacking Sgt1 undergo a mitotic delay due to activation of the spindle checkpoint. The checkpoint response, however, is significantly weakened in Sgt1-depleted cells, and this correlates with a dramatic reduction in kinetochore levels of Mad1, Mad2 and BubR1. These effects are explained by a problem in kinetochore assembly that prevents the localization of Hec1, CENP-E, CENP-F, CENP-I, but not CENP-C, to mitotic kinetochores. Our studies implicate Sgt1 as an essential protein and a critical assembly factor for the mammalian kinetochore, and lend credit to the hypothesis of a kinetochore assembly pathway that is conserved from yeast to man.
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Affiliation(s)
- Peter Steensgaard
- Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy
| | - Massimiliano Garrè
- Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy
| | - Ivan Muradore
- Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy
| | - Pietro Transidico
- Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy
| | - Erich A Nigg
- Department of Cell Biology, Max-Planck Institute for Biochemistry, Am Klopferspitz 18a, 82152 Martinsried, Germany
| | - Katsumi Kitagawa
- Department of Molecular Pharmacology, St Jude Children's Research Hospital, 332 N Lauderdale Street, Memphis, Tennessee 38105-2794, USA
| | - William C Earnshaw
- Wellcome Trust Center for Cell Biology, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Mario Faretta
- Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy
| | - Andrea Musacchio
- Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy
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19
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Abstract
Cancer cells contain abnormal number of chromosomes (aneuploidy), which is a prevalent form of genetic instability in human cancers. Defects in a cell cycle surveillance mechanism called the spindle checkpoint contribute to chromosome instability and aneuploidy. In response to straying chromosomes in mitosis, the spindle checkpoint inhibits the ubiquitin ligase activity of the anaphase-promoting complex or cyclosome (APC/C), thus preventing precocious chromosome segregation and ensuring the accurate partition of the genetic material. We review recent progress toward the understanding of the molecular mechanism of the spindle checkpoint and its role in guarding genome integrity at the chromosome level.
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Affiliation(s)
- Rajnish Bharadwaj
- Department of Pharmacology, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9041, USA
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20
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Abstract
Accumulating evidence points to a key role of the ubiquitin-proteasome pathway in oncogenesis. Aberrant proteolysis of substrates involved in cellular processes such as the cell division cycle, gene transcription, the DNA damage response and apoptosis has been reported to contribute significantly to neoplastic transformation. Cullin-dependent ubiquitin ligases (CDLs) form a class of structurally related multisubunit enzymes central to the ubiquitin-mediated proteolysis of many important biological substrates. In this review, we describe the role of CDLs in the ubiquitinylation of cancer-related substrates and discuss how altered ubiquitinylation by CDLs may contribute to tumor development.
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Affiliation(s)
- Daniele Guardavaccaro
- Department of Pathology and NYU Cancer Institute, MSB 599, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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21
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Murphy TD. Drosophila skpA, a component of SCF ubiquitin ligases, regulates centrosome duplication independently of cyclin E accumulation. J Cell Sci 2003; 116:2321-32. [PMID: 12730292 DOI: 10.1242/jcs.00463] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Centrosome duplication must be coupled to the main cell cycle to ensure that each cell has precisely two centrosomes at the onset of mitosis. Supernumerary centrosomes are commonly observed in cancer cells, and may contribute to tumorigenesis. Drosophila skpA, a component of SCF ubiquitin ligases, regulates the link between the cell and centrosome cycles. Lethal skpA null mutants exhibit dramatic centrosome overduplication and additional defects in chromatin condensation, cell cycle progression and endoreduplication. Surprisingly, many mutant cells are able to organize pseudo-bipolar spindles and execute a normal anaphase in the presence of extra functional centrosomes. SkpA mutant cells accumulate higher levels of cyclin E than wildtype cells during S and G2, suggesting that elevated cdk2/cyclin E activity may account for the supernumerary centrosomes in skpA- cells. However, centrosome overduplication still occurs in skpA-; cycE- mutant animals, demonstrating that high cyclin E levels are not necessary for centrosome overduplication. These data suggest that additional SCF targets regulate the centrosome duplication pathway.
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Affiliation(s)
- Terence D Murphy
- Department of Embryology, Carnegie Institution of Washington, Baltimore, MD 21210, USA.
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22
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Piva R, Liu J, Chiarle R, Podda A, Pagano M, Inghirami G. In vivo interference with Skp1 function leads to genetic instability and neoplastic transformation. Mol Cell Biol 2002; 22:8375-87. [PMID: 12417738 PMCID: PMC134052 DOI: 10.1128/mcb.22.23.8375-8387.2002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Skp1 is involved in a variety of crucial cellular functions, among which the best understood is the formation together with Cul1 of Skp1-cullin-F-box protein ubiquitin ligases. To investigate the role of Skp1, we generated transgenic (Tg) mice expressing a Cul1 deletion mutant (Cul1-N252) able to sequestrate and inactivate Skp1. In vivo interference with Skp1 function through expression of the Cul1-N252 mutant into the T-cell lineage results in lymphoid organ hypoplasia and reduced proliferation. Nonetheless, after a period of latency, Cul1-N252 Tg mice succumb to T-cell lymphomas with high penetrance (>80%). Both T-cell depletion and the neoplastic phenotype of Cul1-N252 Tg mice are largely rescued in Cul1-N252, Skp1 double-Tg mice, indicating that the effects of Cul1-N252 are due to a sequestration of the endogenous Skp1. Analysis of Cul1-N252 lymphomas demonstrates striking karyotype heterogeneity associated with c-myc amplification and c-Myc overexpression. We show that the in vitro expression of the Cul1-N252 mutant causes a pleiotrophic phenotype, which includes the formation of multinucleated cells, centrosome and mitotic spindle abnormalities, and impaired chromosome segregation. Our findings support a crucial role for Skp1 in proper chromosomal segregation, which is required for the maintenance of euploidy and suppression of transformation.
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Affiliation(s)
- Roberto Piva
- Department of Pathology and NYU Cancer Institute. Division of Hematopathology, New York University School of Medicine, New York, New York 10016, USA
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23
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McDonald HB, Helfant AH, Mahony EM, Khosla SK, Goetsch L. Mutational analysis reveals a role for the C terminus of the proteasome subunit Rpt4p in spindle pole body duplication in Saccharomyces cerevisiae. Genetics 2002; 162:705-20. [PMID: 12399382 PMCID: PMC1462277 DOI: 10.1093/genetics/162.2.705] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The ubiquitin/proteasome pathway plays a key role in regulating cell cycle progression. Previously, we reported that a conditional mutation in the Saccharomyces cerevisiae gene RPT4/PCS1, which encodes one of six ATPases in the proteasome 19S cap complex/regulatory particle (RP), causes failure of spindle pole body (SPB) duplication. To improve our understanding of Rpt4p, we created 58 new mutations, 53 of which convert clustered, charged residues to alanine. Virtually all mutations that affect the N-terminal region, which contains a putative nuclear localization signal and coiled-coil motif, result in a wild-type phenotype. Nine mutations that affect the central ATPase domain and the C-terminal region confer recessive lethality. The two conditional mutations identified, rpt4-145 and rpt4-150, affect the C terminus. After shift to high temperature, these mutations generally cause cells to progress slowly through the first cell cycle and to arrest in the second cycle with large buds, a G2 content of DNA, and monopolar spindles, although this phenotype can vary depending on the medium. Additionally, we describe a genetic interaction between RPT4 and the naturally polymorphic gene SSD1, which in wild-type form modifies the rpt4-145 phenotype such that cells arrest in G2 of the first cycle with complete bipolar spindles.
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Affiliation(s)
- Heather B McDonald
- Department of Biology, Colgate University, Hamilton, New York 13346, USA.
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24
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Abstract
Cancer remains one of the leading causes of death throughout the world. One of the important reasons why conventional treatments fail is the development of resistance to therapeutics. The dual effect concept and self-defense mechanism plus the threshold theory might in part explain the development of resistance, however, the primary cause is unclear. A novel theory, 'cell brain', where, selective crystallization of the 'brain' of a cell (comprising centrosome, centrioles and the connecting filaments) occurs, may be a potential alternate approach to cancer therapy.
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Affiliation(s)
- Q Kong
- Cocid Corp, Denver, CO 80220, USA.
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25
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Hansen DV, Hsu JY, Kaiser BK, Jackson PK, Eldridge AG. Control of the centriole and centrosome cycles by ubiquitination enzymes. Oncogene 2002; 21:6209-21. [PMID: 12214251 DOI: 10.1038/sj.onc.1205824] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- David V Hansen
- Programs in Chemical Biology and Cancer Biology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, California, CA 94305-5324, USA
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26
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Mayor T, Hacker U, Stierhof YD, Nigg EA. The mechanism regulating the dissociation of the centrosomal protein C-Nap1 from mitotic spindle poles. J Cell Sci 2002; 115:3275-84. [PMID: 12140259 DOI: 10.1242/jcs.115.16.3275] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The centrosomal protein C-Nap1 is thought to play an important role in centrosome cohesion during interphase of the cell cycle. At the onset of mitosis, when centrosomes separate for bipolar spindle formation, C-Nap1 dissociates from centrosomes. Here we report the results of experiments aimed at determining whether the dissociation of C-Nap1 from mitotic centrosomes is triggered by proteolysis or phosphorylation. Specifically, we analyzed both the cell cycle regulation of endogenous C-Nap1 and the fate of exogenously expressed full-length C-Nap1. Western blot analyses suggested a reduction in the endogenous C-Nap1 level during M phase, but studies using proteasome inhibitors and destruction assays performed in Xenopus extracts argue against ubiquitin-dependent degradation of C-Nap1. Instead, our data indicate that the mitotic C-Nap1 signal is reduced as a consequence of M-phase-specific phosphorylation. Overexpression of full-length C-Nap1 in human U2OS cells caused the formation of large structures that embedded the centrosome and impaired its microtubule nucleation activity. Remarkably, however, these centrosome-associated structures did not interfere with cell division. Instead, centrosomes were found to separate from these structures at the onset of mitosis, indicating that a localized and cell-cycle-regulated activity can dissociate C-Nap1 from centrosomes. A prime candidate for this activity is the centrosomal protein kinase Nek2, as the formation of large C-Nap1 structures was substantially reduced upon co-expression of active Nek2. We conclude that the dissociation of C-Nap1 from mitotic centrosomes is regulated by localized phosphorylation rather than generalized proteolysis.
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Affiliation(s)
- Thibault Mayor
- Department of Cell Biology, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18a, D-82152 Martinsried, Germany
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27
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Abstract
The centrosome is the major microtubule-organizing center of animal cells. It influences cell shape and polarity and directs the formation of the bipolar mitotic spindle. Numerical and structural centrosome aberrations have been implicated in disease, notably cancer. In dividing cells, centrosomes need to be duplicated and segregated in synchrony with chromosomes. This centrosome cycle requires a series of structural and functional transitions that are regulated by both phosphorylation and proteolysis. Here we summarize recent information on the regulation of the centrosome cycle and its coordination with the chromosomal cell cycle.
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Affiliation(s)
- P Meraldi
- Department of Cell Biology, Max-Planck-Institute for Biochemistry, D-82152 Martinsried, Germany
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28
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West CM, van der Wel H, Gaucher EA. Complex glycosylation of Skp1 in Dictyostelium: implications for the modification of other eukaryotic cytoplasmic and nuclear proteins. Glycobiology 2002; 12:17R-27R. [PMID: 11886837 DOI: 10.1093/glycob/12.2.17r] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Recently, complex O-glycosylation of the cytoplasmic/nuclear protein Skp1 has been characterized in the eukaryotic microorganism Dictyostelium. Skp1's glycosylation is mediated by the sequential action of a prolyl hydroxylase and five conventional sugar nucleotide-dependent glycosyltransferase activities that reside in the cytoplasm rather than the secretory compartment. The Skp1-HyPro GlcNAcTransferase, which adds the first sugar, appears to be related to a lineage of enzymes that originated in the prokaryotic cytoplasm and initiates mucin-type O-linked glycosylation in the lumen of the eukaryotic Golgi apparatus. GlcNAc is extended by a bifunctional glycosyltransferase that mediates the ordered addition of beta1,3-linked Gal and alpha1,2-linked Fuc. The architecture of this enzyme resembles that of certain two-domain prokaryotic glycosyltransferases. The catalytic domains are related to those of a large family of prokaryotic and eukaryotic, cytoplasmic, membrane-bound, inverting glycosyltransferases that modify glycolipids and polysaccharides prior to their translocation across membranes toward the secretory pathway or the cell exterior. The existence of these enzymes in the eukaryotic cytoplasm away from membranes and their ability to modify protein acceptors expose a new set of cytoplasmic and nuclear proteins to potential prolyl hydroxylation and complex O-linked glycosylation.
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Affiliation(s)
- Christopher M West
- Department of Anatomy and Cell Biology, 1600 SW Archer Road, University of Florida College of Medicine, Gainesville, FL 32610-0235, USA
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29
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van Der Wel H, Morris HR, Panico M, Paxton T, North SJ, Dell A, Thomson JM, West CM. A non-Golgi alpha 1,2-fucosyltransferase that modifies Skp1 in the cytoplasm of Dictyostelium. J Biol Chem 2001; 276:33952-63. [PMID: 11423539 DOI: 10.1074/jbc.m102555200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Skp1 is a subunit of the SCF-E3 ubiquitin ligase that targets cell cycle and other regulatory factors for degradation. In Dictyostelium, Skp1 is modified by a pentasaccharide containing the type 1 blood group H trisaccharide at its core. To address how the third sugar, fucose alpha1,2-linked to galactose, is attached, a proteomics strategy was applied to determine the primary structure of FT85, previously shown to copurify with the GDP-Fuc:Skp1 alpha 1,2-fucosyltransferase. Tryptic-generated peptides of FT85 were sequenced de novo using Q-TOF tandem mass spectrometry. Degenerate primers were used to amplify FT85 genomic DNA, which was further extended by a novel linker polymerase chain reaction method to yield an intronless open reading frame of 768 amino acids. Disruption of the FT85 gene by homologous recombination resulted in viable cells, which had altered light scattering properties as revealed by flow cytometry. FT85 was necessary and sufficient for Skp1 fucosylation, based on biochemical analysis of FT85 mutant cells and Escherichia coli that express FT85 recombinantly. FT85 lacks sequence motifs that characterize all other known alpha 1,2-fucosyltransferases and lacks the signal-anchor sequence that targets them to the secretory pathway. The C-terminal region of FT85 harbors motifs found in inverting Family 2 glycosyltransferase domains, and its expression in FT85 mutant cells restores fucosyltransferase activity toward a simple disaccharide substrate. Whereas most prokaryote and eukaryote Family 2 glycosyltransferases are membrane-bound and oriented toward the cytoplasm where they glycosylate lipid-linked or polysaccharide precursors prior to membrane translocation, the soluble, eukaryotic Skp1-fucosyltransferase modifies a protein that resides in the cytoplasm and nucleus.
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Affiliation(s)
- H van Der Wel
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, Florida 32610-0235 and the Department of Biochemistry, Imperial College, London SW7 2AY United Kingdom
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30
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Duensing S, Münger K. Centrosome abnormalities, genomic instability and carcinogenic progression. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1471:M81-8. [PMID: 11342187 DOI: 10.1016/s0304-419x(00)00025-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Centrosome abnormalities are a frequent finding in various malignant tumors. Since centrosomes form the poles of the mitotic spindle, these abnormalities have been implicated in chromosome missegregation and the generation of aneuploid cells which is commonly found in many human neoplasms. It is a matter of debate, however, whether centrosome alterations can drive cells into aneuploidy or simply reflect loss of genomic integrity by other mechanisms. Since these two models have fundamentally different implications for the diagnostic and prognostic value of centrosome abnormalities, we will discuss the relevance of abnormal centrosomes in the context of different oncogenic events as exemplified by high-risk human papillomavirus-associated carcinogenesis.
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Affiliation(s)
- S Duensing
- Department of Pathology and Center for Cancer Biology, Harvard Medical School, Armenise Research Building, D2 544A, 200 Longwood Avenue, Boston, MA 02115-5701, USA
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31
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Hinchcliffe EH, Sluder G. "It Takes Two to Tango": understanding how centrosome duplication is regulated throughout the cell cycle. Genes Dev 2001; 15:1167-81. [PMID: 11358861 DOI: 10.1101/gad.894001] [Citation(s) in RCA: 215] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- E H Hinchcliffe
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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32
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Sassi S, Sweetinburgh M, Erogul J, Zhang P, Teng-Umnuay P, West CM. Analysis of Skp1 glycosylation and nuclear enrichment in Dictyostelium. Glycobiology 2001; 11:283-95. [PMID: 11358877 DOI: 10.1093/glycob/11.4.283] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Skp1 is a subunit of SCF-E3 ubiquitin ligases and other protein complexes in the nucleus and cytoplasm of yeast and mammalian cells. In Dictyostelium, Skp1 is partially modified by an unusual pentasaccharide O-linked to hydroxyproline143. This modification was found to be susceptible to known prolyl hydroxylase inhibitors based on M(r)-shift analysis using SDS-polyacrylamide gel electrophoresis/Western blotting. In addition, Dictyostelium Skp1 consists of 2 genetic isoforms, Skp1A and Skp1B, which differ by a single amino acid and appear to be expressed throughout the life cycle based on reverse-transcription polymerase chain reactions. The significance of these structural variations was examined by expressing myc-tagged Skp1s and mutants that lacked the glycosylation site. Gel-based M(r)-shift studies showed that Skp1A and Skp1B are both nearly completely glycosylated during growth and early development, and mass spectrometry of glycopeptides showed that they were glycosylated similarly. Skp1 expressed later in prespore cells was not glycosylated, unlike bulk Skp1 persisting from earlier in development, but became glycosylated after return to growth medium. Skp1A and Skp1B were each concentrated in the nucleus and regions of the cytoplasm, based on immunofluorescence localization. However, when Skp1 glycosylation was blocked by mutation, prolyl hydroxylase inhibitors, or expression in prespore cells, nuclear concentration of Skp1 was not detected. Furthermore, nuclear concentration occurred in a mutant that attached only the core disaccharide to Skp1. Overall, there was no evidence for differential Skp1 isoform expression, glycosylation variants in the bulk Skp1 pool, or regulation of nuclear localization. However, these studies uncovered evidence that the glycosylation pathway is developmentally regulated and can function posttranslationally, and that core glycosylation is required for Skp1's nuclear concentration.
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Affiliation(s)
- S Sassi
- Department of Anatomy and Cell Biology, Box 100235, 1600 SW Archer Road, University of Florida College of Medicine, Gainesville FL 32610-0235, USA
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33
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Sluder G, Hinchcliffe EH. The coordination of centrosome reproduction with nuclear events during the cell cycle. Curr Top Dev Biol 2001; 49:267-89. [PMID: 11005023 DOI: 10.1016/s0070-2153(99)49013-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- G Sluder
- Department of Cell Biology, University of Massachusetts Medical School, Worcester 01605, USA
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34
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Abstract
This year the most prestigious prize in medical sciences, the Lasker Award, has been presented to the three scientists who discovered the ubiquitin pathway: Aaron Ciechanover, Avram Hershko, and Alexander Varshavsky [Nature Med. 6 (2000) 1073-1081]. During a time when the scientific community was focused on understanding how proteins were synthesized, they intently pursued the novel idea that cells were programmed to selectively destroy proteins. Their work led to the identification of an elaborate system of protein degradation targeting a myriad of cellular substrates. A small protein called ubiquitin is at the center of this process. Although the ubiquitin pathway was first described in the early 1980s, it has only more recently advanced to the forefront of basic research as a significant regulatory network within the cell. The field continues to grow as new ubiquitination enzymes and novel functions of this system are identified. Scientists are focused on elucidating the mechanisms by which cells deploy the ubiquitin pathway to control levels of selected proteins, such as cell cycle regulatory proteins, transcription factors and signaling molecules. Accelerated or decelerated rates of degradation of particular substrates participate in the genesis of many human diseases. Thus, understanding the mechanisms that confer specificity to the ubiquitin system will allow the development of novel therapeutic approaches to target aberrations in this pathway underlying tumorigenesis and other human pathologies.
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Affiliation(s)
- L M DeSalle
- Department of Pathology and Kaplan Comprehensive Cancer Center, MSB 548, New York University Medical Center, 550 First Avenue, New York, NY 10016, USA
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35
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Wojcik EJ, Glover DM, Hays TS. The SCF ubiquitin ligase protein slimb regulates centrosome duplication in Drosophila. Curr Biol 2000; 10:1131-4. [PMID: 10996795 DOI: 10.1016/s0960-9822(00)00703-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The duplication of the centrosome is a key event in the cell-division cycle. Although defects in centrosome duplication are thought to contribute to genomic instability [1-3] and are a hallmark of certain transformed cells and human cancer [4-6], the mechanism responsible for centrosome duplication is not understood. Recent experiments have established that centrosome duplication requires the activity of cyclin-dependent kinase 2 (Cdk2) and cyclins E and A [7-9]. The stability of cyclin E is regulated by the ubiquitin ligase SCF, which is a protein complex composed of Skp1, Cdc53 (Cullin) and F-box proteins [10-12]. The Skp1 and Cullin components have been detected on mammalian centrosomes, and shown to be essential for centrosome duplication and separation in Xenopus [13]. Here, we report that Slimb, an F-box protein that targets proteins to the SCFcomplex [14,15], plays a role in limiting centrosome replication. We found that, in the fruit fly Drosophila, the hypomorphic mutation slimb(crd) causes the appearance of additional centrosomes and mitotic defects in mutant larval neuroblasts.
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Affiliation(s)
- E J Wojcik
- Department of Biology, Virginia Tech University, Blacksburg, Virginia, 24061, USA.
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36
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Blondel M, Galan JM, Peter M. Isolation and characterization of HRT1 using a genetic screen for mutants unable to degrade Gic2p in saccharomyces cerevisiae. Genetics 2000; 155:1033-44. [PMID: 10880467 PMCID: PMC1461161 DOI: 10.1093/genetics/155.3.1033] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Skp1p-cullin-F-box (SCF) protein complexes are ubiquitin ligases required for degradation of many regulatory proteins involved in cell cycle progression, morphogenesis, and signal transduction. Using a genetic screen, we have isolated a novel allele of the HRT1/RBX1 gene in budding yeast (hrt1-C81Y). hrt1-C81Y mutant cells exhibited an aberrant morphology but were viable at all temperatures. The cells displayed multiple genetic interactions with mutations in known SCF components and were defective for the degradation of several SCF targets including Gic2p, Far1p, Sic1p, and Cln2p. In addition, they also failed to degrade the F-box proteins Grr1p, Cdc4p, and Met30p. Wild-type Hrt1p but not Hrt1p-C81Y was able to bind multiple F-box proteins in an F-box-dependent manner. Hrt1p-C81Y harbors a single mutation in its ring-finger domain, which is conserved in subunits of distinct E3 ligases. Finally, Hrt1p was localized in both nucleus and cytoplasm and despite a short half-life was expressed constitutively throughout the cell cycle. Taken together, these results suggest that Hrt1p is a core subunit of multiple SCF complexes.
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Affiliation(s)
- M Blondel
- Swiss Institute for Experimental Cancer Research (ISREC), 1066 Epalinges/VD, Switzerland
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Reymond F, Wirbelauer C, Krek W. Association of human ubiquitin-conjugating enzyme CDC34 with the mitotic spindle in anaphase. J Cell Sci 2000; 113 ( Pt 10):1687-94. [PMID: 10769200 DOI: 10.1242/jcs.113.10.1687] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Present in organisms ranging from yeast to man, homologues of the Saccharomyces cerevisiae ubiquitin-conjugating enzyme CDC34 have been shown to play important roles in the regulation of cell cycle progression and checkpoint function. Here we analyze the expression and intracellular localization of endogenous CDC34 during mammalian cell cycle progression. We find that CDC34 protein is constitutively expressed during all stages of the cell cycle. Immunofluorescence experiments reveal that during interphase, endogenous CDC34 is localized to distinct speckles in both the nucleus and the cytoplasm. The presence of CDC34 in these compartments has also been established by biochemical fractionation experiments. Interestingly, nuclear localization depends on the presence of specific carboxy-terminal CDC34 sequences that have previously been shown to be required for CDC34's cell cycle function in Saccharomyces cerevisiae. Finally, we find that in anaphase and not during early stages of mitosis, CDC34 colocalizes with (beta)-tubulin at the mitotic spindle, implying that it may contribute to spindle function at later stages of mitosis. Taken together, these results support a model in which CDC34 ubiquitin-conjugating enzyme functions in the regulation of nuclear and cytoplasmic activities as well as in the process of chromosome segregation at the onset of anaphase in mammalian cells.
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Affiliation(s)
- F Reymond
- Friedrich Miescher Institut, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.
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38
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Nakayama K, Nagahama H, Minamishima YA, Matsumoto M, Nakamichi I, Kitagawa K, Shirane M, Tsunematsu R, Tsukiyama T, Ishida N, Kitagawa M, Nakayama K, Hatakeyama S. Targeted disruption of Skp2 results in accumulation of cyclin E and p27(Kip1), polyploidy and centrosome overduplication. EMBO J 2000; 19:2069-81. [PMID: 10790373 PMCID: PMC305685 DOI: 10.1093/emboj/19.9.2069] [Citation(s) in RCA: 549] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The ubiquitin-proteasome pathway plays an important role in control of the abundance of cell cycle regulators. Mice lacking Skp2, an F-box protein and substrate recognition component of an Skp1-Cullin-F-box protein (SCF) ubiquitin ligase, were generated. Although Skp2(-/-) animals are viable, cells in the mutant mice contain markedly enlarged nuclei with polyploidy and multiple centrosomes, and show a reduced growth rate and increased apoptosis. Skp2(-/-) cells also exhibit increased accumulation of both cyclin E and p27(Kip1). The elimination of cyclin E during S and G(2) phases is impaired in Skp2(-/-) cells, resulting in loss of cyclin E periodicity. Biochemical studies showed that Skp2 interacts specifically with cyclin E and thereby promotes its ubiquitylation and degradation both in vivo and in vitro. These results suggest that specific degradation of cyclin E and p27(Kip1) is mediated by the SCF(Skp2) ubiquitin ligase complex, and that Skp2 may control chromosome replication and centrosome duplication by determining the abundance of cell cycle regulators.
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Affiliation(s)
- K Nakayama
- Laboratory of Embryonic and Genetic Engineering, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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39
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Abstract
The ubiquitin system drives the cell division cycle by the timely destruction of numerous regulatory proteins. Remarkably, the two main activities that catalyze substrate ubiquitination in the cell cycle, the Skp1-Cdc53/cullin-F-box protein (SCF) complexes and the anaphase-promoting complex/cyclosome (APC/C), define a new superfamily of E3 ubiquitin ligases, all based on related cullin and RING-H2 finger protein subunits. The circuits that interconnect the SCF, APC/C and cyclin-dependent kinase activities form a master oscillator that coordinates the replication and segregation of the genome.
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Affiliation(s)
- M Tyers
- Programme in Molecular Biology and Cancer, Graduate Department of Molecular and Medical Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, M5G 1X5, M5S 1A8, Canada.
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40
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Abstract
Protein degradation is deployed to modulate the steady-state abundance of proteins and to switch cellular regulatory circuits from one state to another by abrupt elimination of control proteins. In eukaryotes, the bulk of the protein degradation that occurs in the cytoplasm and nucleus is carried out by the 26S proteasome. In turn, most proteins are thought to be targeted to the 26S proteasome by covalent attachment of a multiubiquitin chain. Ubiquitination of proteins requires a multienzyme system. A key component of ubiquitination pathways, the ubiquitin ligase, controls both the specificity and timing of substrate ubiquitination. This review is focused on a conserved ubiquitin ligase complex known as SCF that plays a key role in marking a variety of regulatory proteins for destruction by the 26S proteasome.
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Affiliation(s)
- R J Deshaies
- Department of Biology, California Institute of Technology, Pasadena 91125, USA.
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