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Li S, Li X, Xu A, Zhang B, He X, Chen H, Huang J. Screening and clinical evaluation of dominant peptides of centromere protein F antigen for early diagnosis of hepatocellular carcinoma. Mol Med Rep 2018; 17:4720-4728. [PMID: 29328419 DOI: 10.3892/mmr.2018.8372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 11/22/2017] [Indexed: 11/06/2022] Open
Abstract
Tumor-associated antigens, such as centromere protein F (CENP‑F), have been recognized as potential serological biomarkers for early diagnosis of hepatocellular carcinoma (HCC); however, the exact regions corresponding to the dominant peptides of CENP‑F antigen remain to be explored. We aimed to screen and evaluate potential dominant peptides of CENP‑F for early diagnosis of HCC. Dominant peptides of CENP‑F were predicted by BioSun version 3.0, and the corresponding recombinant proteins were prepared. Enzyme‑linked immunosorbent assays were conducted for initial screening of dominant peptides, and selected dominant peptides were subjected to further clinical evaluation. Eight dominant peptides of CENP‑F antigens were predicted at amino acids (a.a) 121‑220, 335‑416, 1100‑1265, 1670‑1791, 1759‑2093, 2075‑2210, 2485‑2592, and 2808‑2960. Initial screening of the predicted peptides in samples of 47 HCC cases showed the highest diagnostic value for 121‑220 a.a and 1670‑1791 a.a peptides with area under the curve (AUC) values of 0.795 [95% confidence interval (CI), 0.706‑0.884] and 0.809 (95% CI, 0.721‑0.896), sensitivity of 58.3 and 85.4%, and specificity of 93.9 and 65.3%, respectively. Further evaluation of the two peptides in 405 samples comprised of 153 HCC, 126 liver cirrhosis and 126 healthy controls, presenting an AUC of 0.743 (95% CI, 0.674‑0.812) for 121‑220 a.a peptide in detecting early‑stage HCCs. Specifically, the 121‑220 a.a peptide showed a complementary effect in combination with α‑fetoprotein (AFP) for the detection of early‑stage HCC with increased AUC value of 0.840 (95% CI, 0.781‑0.899), and sensitivity of 81.4% and specificity of 72.2%. In conclusion, our study identified the 121‑220 a.a dominant peptide as the region of CENP‑F antigen with the highest immunogenicity and demonstrated its value in combination with AFP for diagnosis of early-stage HCC.
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Affiliation(s)
- Siwen Li
- Liver Research Center, Experimental Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine in Liver Cirrhosis, Beijing, 100050, P.R. China
| | - Xiaojin Li
- Liver Research Center, Experimental Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine in Liver Cirrhosis, Beijing, 100050, P.R. China
| | - Anjian Xu
- Liver Research Center, Experimental Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine in Liver Cirrhosis, Beijing, 100050, P.R. China
| | - Bei Zhang
- Liver Research Center, Experimental Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine in Liver Cirrhosis, Beijing, 100050, P.R. China
| | - Xiaomin He
- Liver Research Center, Experimental Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine in Liver Cirrhosis, Beijing, 100050, P.R. China
| | - Hongda Chen
- Program Office for Cancer Screening in Urban China, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, P.R. China
| | - Jian Huang
- Liver Research Center, Experimental Center, Beijing Friendship Hospital, Capital Medical University, Beijing Key Laboratory of Translational Medicine in Liver Cirrhosis, Beijing, 100050, P.R. China
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Welner S, Trier NH, Frisch M, Locht H, Hansen PR, Houen G. Correlation between centromere protein-F autoantibodies and cancer analyzed by enzyme-linked immunosorbent assay. Mol Cancer 2013; 12:95. [PMID: 23978088 PMCID: PMC3844405 DOI: 10.1186/1476-4598-12-95] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 08/22/2013] [Indexed: 11/10/2022] Open
Abstract
Background Centromere protein-F (CENP-F) is a large nuclear protein of 367 kDa, which is involved in multiple mitosis-related events such as proper assembly of the kinetochores, stabilization of heterochromatin, chromosome alignment and mitotic checkpoint signaling. Several studies have shown a correlation between CENP-F and cancer, e.g. the expression of CENP-F has been described to be upregulated in cancer cells. Furthermore, several studies have described a significant correlation between the expression of autoantibodies to CENP-F and cancer. Methods Autoantibodies to CENP-F were detected in a small number of samples during routine indirect immunofluorescence (IIF) analysis for anti-nuclear antibodies (ANA) using HEp-2 cells as substrate. Using overlapping synthetic peptides covering a predicted structural maintenance of chromosomes (SMC) domain, we developed an enzyme-linked immunosorbent assay (ELISA) for detection of CENP-F antibodies. Results Analyzing the reactivity of the sera positive in IIF for CENP-F antibodies to overlapping CENP-F peptides, we showed that autoantibodies to several peptides correlate with the presence of antibodies to CENP-F and a diagnosis of cancer, as increased CENP-F antibody expression specific for malignant cancer patients to five peptides was found (A9, A12, A14, A16, A27). These antibodies to CENP-F in clinical samples submitted for ANA analysis were found to have a positive predictive value for cancer of 50%. Furthermore, the expression of cancer-correlated CENP-F antibodies seemed to increase as a function of time from diagnosis. Conclusion These results conform to previous findings that approximately 50% of those patients clinically tested for ANA analyses who express CENP-F antibodies are diagnosed with cancer, confirming that these antibodies may function as circulating tumor markers. Thus, a peptide-based CENP-F ELISA focused on the SMC domain may aid in identifying individuals with a potential cancer.
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Affiliation(s)
- Simon Welner
- Department of Clinical Biochemistry, Immunology and Genetics, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark.
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Du J, Zhang Y, Liu Y, Li Y, Zhu X. Involvement of Cenp-F in interphase chromatin organization possibly through association with DNA-dependent protein kinase. Acta Biochim Biophys Sin (Shanghai) 2010; 42:839-46. [PMID: 20978035 DOI: 10.1093/abbs/gmq095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Cenp-F (also named mitosin) is a 350-kDa human kinetochore protein important for the mitotic progression. It is also a nuclear matrix protein in interphase cells. Here, we showed that overexpression of N-terminal deletion mutants of Cenp-F containing the C-terminal 112 residues induced chromatin condensation into numerous aggregates of varying sizes in interphase nucleus, colocalizing with the exogenous proteins. In situ hybridization using whole chromosome painting probes indicated that the chromatin aggregates were not prematurely condensed individual chromosomes. Neither were they due to apoptosis. We provided evidence showing association of Cenp-F with certain regions of interphase chromatin fibers. Cenp-F associated with the DNA-dependent protein kinase (DNA-PK), a trimeric protein complex critical for genome homeostasis. Moreover, the DNA-PK association activity of Cenp-F mutants correlated with their ability to induce chromatin aggregation. These results imply a role of Cenp-F in organization of interphase chromatin through association and possibly regulation of DNA-PK.
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Affiliation(s)
- Juan Du
- Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, China
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4
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Du J, Li Y, Zhu X. Involvement of CENP-F in histone methylation. Acta Biochim Biophys Sin (Shanghai) 2010; 42:173-6. [PMID: 20213041 DOI: 10.1093/abbs/gmq001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
CENP-F (also named mitosin) is a multifunctional protein of 350 kDa. In interphase, it is a nuclear protein, whereas in M phase it localizes to the kinetochore, the major microtubule-binding structure on chromosomes essential for chromosome segregation. CENP-F is also critical for myocyte differentiation through the interaction with Rb. It binds to ATF4 and negatively regulates the transcriptional activity of ATF4. It is also important for mitotic progression. Here we show that depletion of CENP-F by RNAi markedly downregulated the methylation of histone H3 at K4 and K9. Consistently, association of HP1a with mitotic chromosomes was largely decreased. These results uncover a novel role of CENP-F in regulation of epigenetic modification on histone H3.
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Affiliation(s)
- Juan Du
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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Pooley RD, Moynihan KL, Soukoulis V, Reddy S, Francis R, Lo C, Ma LJ, Bader DM. Murine CENPF interacts with syntaxin 4 in the regulation of vesicular transport. J Cell Sci 2008; 121:3413-21. [PMID: 18827011 DOI: 10.1242/jcs.032847] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Syntaxin 4 is a component of the SNARE complex that regulates membrane docking and fusion. Using a yeast two-hybrid screen, we identify a novel interaction between syntaxin 4 and cytoplasmic murine CENPF, a protein previously demonstrated to associate with the microtubule network and SNAP-25. The binding domain for syntaxin 4 in CENPF was defined by yeast two-hybrid assay and co-immunoprecipitation. Confocal analyses in cell culture reveal a high degree of colocalization between endogenously expressed proteins in interphase cells. Additionally, the endogenous SNARE proteins can be isolated as a complex with CENPF in immunoprecipitation experiments. Further analyses demonstrate that murine CENPF and syntaxin 4 colocalize with components of plasma membrane recycling: SNAP-25 and VAMP2. Depletion of endogenous CENPF disrupts GLUT4 trafficking whereas expression of a dominant-negative form of CENPF inhibits cell coupling. Taken together, these studies demonstrate that CENPF provides a direct link between proteins of the SNARE system and the microtubule network and indicate a diverse role for murine CENPF in vesicular transport.
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Affiliation(s)
- Ryan D Pooley
- Stahlman Cardiovascular Research Laboratories, Program for Developmental Biology, and Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232-6300, USA
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Dees E, Robertson JB, Zhu T, Bader D. Specific deletion of CMF1 nuclear localization domain causes incomplete cell cycle withdrawal and impaired differentiation in avian skeletal myoblasts. Exp Cell Res 2006; 312:3000-14. [PMID: 16904105 DOI: 10.1016/j.yexcr.2006.06.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Revised: 05/31/2006] [Accepted: 06/01/2006] [Indexed: 11/17/2022]
Abstract
CMF1 is a protein expressed in embryonic striated muscle with onset of expression preceding that of contractile proteins. Disruption of CMF1 in myoblasts disrupts muscle-specific protein expression. Preliminary studies indicate both nuclear and cytoplasmic distribution of CMF1 protein, suggesting functional roles in both cellular compartments. Here we examine the nuclear function of CMF1, using a newly characterized antibody generated against the CMF1 nuclear localization domain and a CMF1 nuclear localization domain-deleted stable myocyte line. The antibody demonstrates nuclear distribution of the CMF1 protein both in vivo and in cell lines, with clustering of CMF1 protein around chromatin during mitosis. In more differentiated myocytes, the protein shifts to the cytoplasm. The CMF1 NLS-deleted cell lines have markedly impaired capacity to differentiate. Specifically, these cells express less contractile protein than wild-type or full-length CMF1 stably transfected cells, and do not fuse properly into multinucleate syncytia with linear nuclear alignment. In response to low serum medium, a signal to differentiate, CMF1 NLS-deleted cells enter G0, but continue to express proliferation markers and will reenter the cell cycle when stimulated by restoring growth medium. These data suggest that CMF1 is involved in regulation the transition from proliferation to differentiation in embryonic muscle.
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Affiliation(s)
- Ellen Dees
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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Varis A, Salmela AL, Kallio MJ. Cenp-F (mitosin) is more than a mitotic marker. Chromosoma 2006; 115:288-95. [PMID: 16565862 DOI: 10.1007/s00412-005-0046-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Revised: 12/02/2005] [Accepted: 12/15/2005] [Indexed: 12/18/2022]
Abstract
Cenp-F (mitosin) is a large coiled-coil protein whose function has remained obscure since its identification a decade ago. It has been suggested that the protein plays a role in the kinetochore-mediated mitotic functions but until recently there was little evidence to support this postulation. Recent results from five laboratories have given insights on how Cenp-F may participate in the regulation of cell division. In this mini-review, we will summarize the current data regarding the mitotic tasks of Cenp-F as well as discuss how it is used as a proliferation marker of malignant cell growth in the clinic. Also, the protein's post-translational modification by farnesylation and potential contribution to cell cycle effects of farnesyl transferase inhibitors will be addressed.
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Affiliation(s)
- Asta Varis
- Cancer Biology and Cell Screening Department, VTT Medical Biotechnology, Itäinen Pitkäkatu 4A, 20521, Turku, Finland
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Dees E, Robertson JB, Ashe M, Pabón-Peña LM, Bader D, Goodwin RL. LEK1 protein expression in normal and dysregulated cardiomyocyte mitosis. ACTA ACUST UNITED AC 2006; 286:823-32. [PMID: 16047383 DOI: 10.1002/ar.a.20221] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A defining characteristic of embryonic cells is their ability to divide rapidly, even in tissues such as cardiac muscle, which cannot divide once fully differentiated. This suggests that regulators of cell division differ in embryonic and differentiated cells. LEK1 is a member of an emerging family of proteins with diverse functions but shared structural domains, including numerous leucine zippers, a nuclear localization site, and a functional Rb-binding domain. LEK1 is expressed ubiquitously in the developing mouse embryo from the earliest stages of differentiation through birth. It is absent in adult tissues, even those that maintain active cell division. We hypothesize that LEK1 is a regulator of mitosis restricted to the developing embryo and early neonate. Here, using BrdU incorporation, we show that LEK1 protein downregulation in cardiac myocytes correlates directly with cessation of DNA synthesis between neonatal days 6 and 10. In contrast, in an immortalized cardiac cell line (HL1 cells), both BrdU incorporation and LEK1 protein expression persist, and actively dividing cells express LEK1. However, BrdU incorporation can be decreased in these cells by treatment with a morpholino targeting LEK1 mRNA. These data suggest a role for LEK1 in regulating the normal embryonic cardiomyocyte cell cycle and in promoting continued mitosis in transformed, abnormally dividing cardiomyocytes.
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Affiliation(s)
- Ellen Dees
- Gladys P. Stahlman Cardiovascular Research Laboratory, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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9
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Yang Z, Guo J, Chen Q, Ding C, Du J, Zhu X. Silencing mitosin induces misaligned chromosomes, premature chromosome decondensation before anaphase onset, and mitotic cell death. Mol Cell Biol 2005; 25:4062-74. [PMID: 15870278 PMCID: PMC1087709 DOI: 10.1128/mcb.25.10.4062-4074.2005] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Mitosin (also named CENP-F) is a large human nuclear protein transiently associated with the outer kinetochore plate in M phase. Using RNA interference and fluorescence microscopy, we showed that mitosin depletion attenuated chromosome congression and led to metaphase arrest with misaligned polar chromosomes whose kinetochores showed few cold-stable microtubules. Kinetochores of fully aligned chromosomes often failed to show orientation in the direction of the spindle long axis. Moreover, tension across their sister kinetochores was decreased by 53% on average. These phenotypes collectively imply defects in motor functions in mitosin-depleted cells and are similar to those of CENP-E depletion. Consistently, the intensities of CENP-E and cytoplasmic dynein and dynactin, which are motors controlling microtubule attachment and chromosome movement, were reduced at the kinetochore in a microtubule-dependent manner. In addition, after being arrested in pseudometaphase for approximately 2 h, mitosin-depleted cells died before anaphase initiation through apoptosis. The dying cells exhibited progressive chromosome arm decondensation, while the centromeres were still associated with spindles. Mitosin is therefore essential for full chromosome alignment, possibly by promoting proper kinetochore attachments through modulating CENP-E and dynein functions. Its depletion also prematurely triggers chromosome decondensation, a process that normally occurs from telophase for the nucleus reassembly, thus resulting in apoptosis.
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Affiliation(s)
- Zhenye Yang
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China
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10
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Yang ZY, Guo J, Li N, Qian M, Wang SN, Zhu XL. Mitosin/CENP-F is a conserved kinetochore protein subjected to cytoplasmic dynein-mediated poleward transport. Cell Res 2003; 13:275-83. [PMID: 12974617 DOI: 10.1038/sj.cr.7290172] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Mitosin/CENP-F is a human nuclear protein transiently associated with the outer kinetochore plate in M phase and is involved in M phase progression. LEK1 and CMF1, which are its murine and chicken orthologs, however, are implicated in muscle differentiation and reportedly not distributed at kinetochores. We therefore conducted several assays to clarify this issue. The typical centromere staining patterns were observed in mitotic cells from both human primary culture and murine, canine, and mink cell lines. A C-terminal portion of LEK1 also conferred centromere localization. Our analysis further suggests conserved kinetochore localization of mammalian mitosin orthologs. Moreover, mitosin was associated preferentially with kinetochores of unaligned chromosomes. It was also constantly transported from kinetochores to spindle poles by cytoplasmic dynein. These properties resemble those of other kinetochore proteins important for the spindle checkpoint, thus implying a role of mitosin in this checkpoint. Therefore, mitosin family may serve as multifunctional proteins involved in both mitosis and differentiation.
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Affiliation(s)
- Zhen Ye Yang
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
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Abstract
Sedlin is an evolutionarily conserved protein encoded by the causative gene SEDL for spondyloepiphyseal dysplasia tarda. Nevertheless, how Sedlin mutations cause the disease remains unknown. Here, the intracellular chloride channel protein CLIC1 was shown to associate with Sedlin by yeast two-hybrid screening. Green fluorescence protein-CLIC1 readily co-immunoprecipitated with FLAG-Sedlin. In addition, both proteins colocalized extensively in cytoplasmic vesicular/reticular structures in COS-7 cells, suggesting their interaction at intracellular membranous organelles. Sedlin also associated with CLIC2 in yeast two-hybrid assays. The link between Sedlin and the intracellular chloride channels is the first step to understand their functional interplays.
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Affiliation(s)
- Libin Fan
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, PR China
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Yan X, Li F, Liang Y, Shen Y, Zhao X, Huang Q, Zhu X. Human Nudel and NudE as regulators of cytoplasmic dynein in poleward protein transport along the mitotic spindle. Mol Cell Biol 2003; 23:1239-50. [PMID: 12556484 PMCID: PMC141156 DOI: 10.1128/mcb.23.4.1239-1250.2003] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Emerging evidence supports the idea that a signaling pathway containing orthologs of at least mammalian NudE and Nudel, Lis1, and cytoplasmic dynein is conserved for eukaryotic nuclear migration. In mammals, this pathway has profound impact on neuronal migration during development of the central nervous system. Lis1 and dynein are also involved in other cellular functions, such as mitosis. Here we show that Nudel also participates in a subset of dynein function in M phase. Nudel was specifically phosphorylated in M phase in its serine/threonine phosphorylation motifs, probably by Cdc2 and also Erk1 and -2. A fraction of Nudel bound to centrosomes strongly in interphase and localized to mitotic spindles in early M phase. By using mutants incapable of or simulating phosphorylation, we confirmed that phosphorylation of Nudel regulated the cell-cycle-dependent distribution, possibly by increasing its dissociation rate at the microtubule-organizing center. Moreover, phosphorylated Nudel or the phosphorylation-mimicking mutant bound Lis1 more efficiently. We further demonstrated that a Nudel mutant incapable of binding to Lis1 impaired the poleward movement of dynein and hence the dynein-mediated transport of kinetochore proteins to spindle poles along microtubules, a process contributing to inactivation of the spindle checkpoint in mitosis. These results point to the importance of Nudel-Lis1 interaction for the dynein activity in M phase and to a possible role of Nudel phosphorylation as facilitating such interaction. In addition, comparative studies suggest that NudE is also functionally related to its paralog, Nudel.
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Affiliation(s)
- Xiumin Yan
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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Hussein D, Taylor SS. Farnesylation of Cenp-F is required for G2/M progression and degradation after mitosis. J Cell Sci 2002; 115:3403-14. [PMID: 12154071 DOI: 10.1242/jcs.115.17.3403] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Farnesyl transferase inhibitors induce G2/M cell cycle delays that cannot be explained by inhibition of the Ras GTPase. Recently, the kinetochore protein Cenp-F has been shown to be farnesylated. Here, we show that ectopic expression of the kinetochore targeting domain of Cenp-F delays progression through G2/M. Significantly, this is dependent on the CAAX farnesylation motif. We also show that localisation of Cenp-F to the nuclear envelope at G2/M and kinetochores in prometaphase is dependent both on its CAAX motif and farnesyl transferase activity. Strikingly, farnesyl transferase activity is also required for Cenp-F degradation after mitosis. Thus, these observations suggest that farnesylation of Cenp-F is required not only for its localisation to the nuclear envelope and kinetochores but also for timely progression through G2/M and its degradation after mitosis. In addition, these observations raise the possibility that the anti-proliferative effects induced by farnesyl transferase inhibitors may be due to inhibition of Cenp-F function and/or turnover.
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Affiliation(s)
- Deema Hussein
- School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, UK
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Xu K, Ludueña RF. Characterization of nuclear betaII-tubulin in tumor cells: a possible novel target for taxol. CELL MOTILITY AND THE CYTOSKELETON 2002; 53:39-52. [PMID: 12211114 DOI: 10.1002/cm.10060] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
As the subunits of microtubules, alpha- and beta-tubulins have been thought to only exist in the cytoplasm where they are incorporated into microtubules. However, the beta(II) isotype of tubulin has recently been observed in the nuclei of rat kidney mesangial cells [Walss et al., 1999: Cell Motil. Cytoskeleton 42:274-284]. In this study, we detected nuclear beta(II)-tubulin in rat C6 glioma cells, human T98G glioma cells, human MCF-7 breast carcinoma cells, human MDA-MB-435 breast carcinoma cells, and human Hela cervix carcinoma cells. In addition, nuclear beta(II)-tubulin in these cells was found to exist as alphabeta(II) dimers instead of assembled microtubules and appeared to be particularly concentrated in the nucleoli. Several anti-tubulin drugs were used to treat C6 cells to determine their influence on nuclear beta(II)-tubulin. Taxol, a tubulin drug with higher specificity for beta(II)-tubulin than for other beta-tubulin isotypes, irreversibly decreased nuclear beta(II) content in a concentration-dependent manner in C6 cells. Meanwhile, cells were found to be apoptotic as was suggested by the presence of multiple micronuclei and DNA fragmentation. On the other hand, no depletion of nuclear beta(II)-tubulin was observed when C6 cells were incubated with colchicine or nocodazole, two anti-tubulin drugs with higher specificity for the alphabeta(IV) isotype, supporting the hypothesis that drugs with higher specificity for beta(II)-tubulin deplete nuclear beta(II)-tubulin.
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Affiliation(s)
- Keliang Xu
- Department of Biochemistry, The University of Texas Health Science Center at San Antonio, 78229-3900, USA
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Abstract
Studies of the retinoblastoma gene (Rb) have shown that its protein product (pRb) acts to restrict cell proliferation, inhibit apoptosis, and promote cell differentiation. The frequent mutation of the Rb gene, and the functional inactivation of pRb in tumor cells, have spurred interest in the mechanism of pRb action. Recently, much attention has focused on pRb's role in the regulation of the E2F transcription factor. However, biochemical studies have suggested that E2F is only one of many pRb-targets and, to date, at least 110 cellular proteins have been reported to associate with pRb. The plethora of pRb-binding proteins raises several important questions. How many functions does pRb possess, which of these functions are important for development, and which contribute to tumor suppression? The goal of this review is to summarize the current literature of pRb-associated proteins.
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Affiliation(s)
- E J Morris
- Laboratory of Molecular Oncology, Massachusetts General Hospital Cancer Center, Charlestown, Massachusetts 02129, USA
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Walss-Bass C, Kreisberg JI, Ludueña RF. Mechanism of localization of betaII-tubulin in the nuclei of cultured rat kidney mesangial cells. CELL MOTILITY AND THE CYTOSKELETON 2001; 49:208-17. [PMID: 11746665 DOI: 10.1002/cm.1034] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Tubulin is an alphabeta heterodimer. Both the alpha and beta polypeptides exist as multiple isotypes. Although tubulin was generally thought to exist only in the cytoplasm, we have previously reported the presence of the betaII isotype of tubulin in the nuclei of cultured rat kidney mesangial cells, smooth-muscle-like cells that reside in the glomerular mesangium; nuclear betaII exists as an alphabetaII dimer, capable of binding to colchicine, but in non-microtubule form [Walss et al., 1999: Cell Motil. Cytoskeleton 42:274-284]. We have now investigated the nature of the process by which alphabetaII enters the nuclei of these cells. By micro-injecting fluorescently labeled alphabetaII into mesangial cells, we found that alphabetaII was present in the nuclei of cells only if they were allowed to go through mitosis. In contrast, there were no circumstances in which microinjected fluorescently labeled abetaII or alphabetaIV dimers entered the nuclei. These findings, together with the absence of any nuclear localization signal in alphabetaII, strongly favor the model that alphabetaII, rather than being transported into the intact nucleus, co-assembles with the nucleus at the end of mitosis. Our results also indicate that the nuclear localization mechanism is specific for alphabetaII. This result raises the possibility that alphabetaII may have a specific function that requires its presence in the nuclei of cultured rat kidney mesangial cells.
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Affiliation(s)
- C Walss-Bass
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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Ashar HR, James L, Gray K, Carr D, Black S, Armstrong L, Bishop WR, Kirschmeier P. Farnesyl transferase inhibitors block the farnesylation of CENP-E and CENP-F and alter the association of CENP-E with the microtubules. J Biol Chem 2000; 275:30451-7. [PMID: 10852915 DOI: 10.1074/jbc.m003469200] [Citation(s) in RCA: 262] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human tumor cell lines that are sensitive to the effects of farnesyl transferase inhibitors accumulate in G(2) --> M (except for cells with an activated Ha-ras that accumulate in G(1)). A search for CAAX box proteins from Swiss-Prot revealed more than 300 peptides. Of these, the centromeric proteins CENP-E and CENP-F are preferentially expressed during mitosis and are implicated as mediators of the G(2) --> M checkpoint. Experiments performed here show that peptides from the COOH-terminal CAAX box of CENP-E and CENP-F are substrates for farnesyl transferase but not geranylgeranyl transferase-I. Although both proteins are prenylated in the human tumor cell line DLD-1, their prenylation is completely inhibited by the farnesyl transferase inhibitor, SCH 66336. Immunohistochemical data with the lung carcinoma cell line, A549, showed that preventing the farnesylation of CENP-E and CENP-F by treatment with the farnesyl transferase inhibitor SCH 66336 does not affect their localization to the kinetochores. However, the presence of farnesyl transferase inhibitors alters the association between CENP-E and the microtubules. Our results imply that the inhibition of CENP-E farnesylation results in the alteration of the microtubule-centromere interaction during mitosis and results in the accumulation of cells prior to metaphase.
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Affiliation(s)
- H R Ashar
- Department of Tumor Biology, Schering-Plough Research Institute, Kenilworth, New Jersey 07033, USA
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18
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Warner AK, Sloboda RD. C-terminal domain of the mitotic apparatus protein p62 targets the protein to the nucleolus during interphase. CELL MOTILITY AND THE CYTOSKELETON 2000; 44:68-80. [PMID: 10470020 DOI: 10.1002/(sici)1097-0169(199909)44:1<68::aid-cm6>3.0.co;2-l] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mitotic apparatuses from sea urchin embryos contain a protein (p62), previously shown to be required for mitotic progression. This protein localizes to the mitotic apparatus during cell division in urchin embryos and mammalian tissue culture cells. We show here by immunofluorescence that p62 is localized to the nucleus of mammalian cells during interphase and is highly concentrated in nucleoli. In addition, a fusion protein composed of full-length p62 and green fluorescent protein also localizes to nucleoli when expressed in COS-7 cells in culture. Analysis of the primary sequence of p62 reveals three distinct domains of the protein based on amino acid charge distribution: the acidic N-terminal domain, the basic C-terminal domain, and the central, M-domain, which contains alternating subdomains of clusters of acidic and basic residues. To identify the domain important for nucleolar localization during interphase, specific domains of p62 alone, or in combination with each other or with beta-galactosidase were fused to green fluorescent protein. Following confirmation of the fusion constructs by sequence analysis, the constructs were expressed in mammalian cells, expression was confirmed by immunoblotting, and the fusion proteins were localized via fluorescence microscopy. The data demonstrate that the C-terminal domain of p62 is both necessary and sufficient for the nuclear localization and nucleolar binding of p62 that is observed during interphase.
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Affiliation(s)
- A K Warner
- Department of Biological Sciences, 6044 Gilman Laboratory, Dartmouth College, Hanover, New Hampshire 03755, USA
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Maney T, Ginkel LM, Hunter AW, Wordeman L. The kinetochore of higher eucaryotes: a molecular view. INTERNATIONAL REVIEW OF CYTOLOGY 1999; 194:67-131. [PMID: 10494625 DOI: 10.1016/s0074-7696(08)62395-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
This review summarizes results concerning the molecular nature of the higher eucaryotic kinetochore. The first major section of this review includes kinetochore proteins whose general functions remain to be determined, precluding their entry into a discrete functional category. Many of the proteins in this section, however, are likely to be involved in kinetochore formation or structure. The second major section is concerned with how microtubule motor proteins function to cause chromosome movement. The microtubule motors dynein, CENP-E, and MCAK have all been observed at the kinetochore. While their precise functions are not well understood, all three are implicated in chromosome movement during mitosis. Finally, the last section deals with kinetochore components that play a role in the spindle checkpoint; a checkpoint that delays mitosis until all kinetochores have attached to the mitotic spindle. Brief reviews of kinetochore morphology and of an important technical breakthrough that enabled the molecular dissection of the kinetochore are also included.
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Affiliation(s)
- T Maney
- Department of Physiology and Biophysics, University of Washington, Seattle 98195, USA
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20
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Zhao J, Ben LH, Wu YL, Hu W, Ling K, Xin SM, Nie HL, Ma L, Pei G. Anti-HIV agent trichosanthin enhances the capabilities of chemokines to stimulate chemotaxis and G protein activation, and this is mediated through interaction of trichosanthin and chemokine receptors. J Exp Med 1999; 190:101-11. [PMID: 10429674 PMCID: PMC2195565 DOI: 10.1084/jem.190.1.101] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Trichosanthin (TCS), an active protein component isolated from a traditional Chinese medicinal herb Trichosanthes kirilowii, has been shown to inhibit HIV infection and has been applied in clinical treatment of AIDS. The recent development that chemokines and chemokine receptors play important roles in HIV infection led us to investigate the possible functional interaction of TCS with chemokines and their receptors. This study demonstrated that TCS greatly enhanced both RANTES (regulated upon activation, normal T cell expressed and secreted)- and stromal cell-derived factor (SDF)-1 alpha-stimulated chemotaxis (EC50 approximately equal to 1 nM) in leukocytes (THP-1, Jurkat, and peripheral blood lymphocyte cells) and activation of pertussis toxin-sensitive G proteins (EC50 approximately equal to 20 nM). TCS also significantly augmented chemokine-stimulated activation of chemokine receptors CCR5 and CXCR4 as well as CCR1, CCR2B, CCR3, and CCR4 transiently expressed in HEK293 cells. A mutant TCS with 4,000-fold lower ribosome-inactivating activity showed similar augmentation activity as wild-type TCS. Moreover, flow cytometry demonstrated that the specific association of TCS to the cell membranes required the presence of chemokine receptors, and laser confocal microscopy reveals that TCS was colocalized with chemokine receptors on the membranes. The results from TCS-Sepharose pull-down and TCS and chemokine receptor coimmunoprecipitation and cross-linking experiments demonstrated association of TCS with CCR5. Thus, our data clearly demonstrated that TCS synergizes activities of chemokines to stimulate chemotaxis and G protein activation, and the effects of TCS are likely to be mediated through its interaction with chemokine receptors.
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Affiliation(s)
- J Zhao
- Shanghai Institute of Cell Biology, Chinese Academy of Sciences, People's Republic of China
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21
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Goodwin RL, Pabón-Peña LM, Foster GC, Bader D. The cloning and analysis of LEK1 identifies variations in the LEK/centromere protein F/mitosin gene family. J Biol Chem 1999; 274:18597-604. [PMID: 10373470 DOI: 10.1074/jbc.274.26.18597] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report the cloning of a novel murine cDNA, LEK1, that is related to human CENP-F and mitosin and more distantly to chicken CMF1. The proteins from these three organisms have significant homology, yet differ in their temporal, spatial, and subcellular localizations. The human proteins bind the kinetochore in mitotic cells, whereas the chicken protein is found only in skeletal and cardiac muscle and is developmentally regulated. Mouse LEK1 is a single copy gene that codes for two developmentally regulated transcripts. The LEK1 protein is expressed early and ubiquitously in mouse development and is generally down-regulated as development proceeds in a manner that correlates to a cessation of mitosis. In adult tissues, the LEK1 protein is detected exclusively in the pronucleus of the oocyte and was not observed in other actively dividing tissues. Subcellular localization revealed that the LEK1 protein in mitotic cells does not bind the kinetochore. From these data, we hypothesize that chicken CMF1, human CENP-F, mitosin, and mouse LEK1 are members of an emerging family of genes that have important and functionally distinct roles in development and cell division.
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Affiliation(s)
- R L Goodwin
- Gladys P. Stahlman Cardiovascular Research Laboratory, Vanderbilt University Medical Center, Nashville, Tennessee 37212-6300, USA
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22
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Zhu X. Structural requirements and dynamics of mitosin-kinetochore interaction in M phase. Mol Cell Biol 1999; 19:1016-24. [PMID: 9891037 PMCID: PMC116032 DOI: 10.1128/mcb.19.2.1016] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mitosin is a 350-kDa human nuclear protein which transiently associates with centromeres and spindle poles in M phase. Ultrastructure studies reveal that it is located at the outer kinetochore plate. In this work, we explored the detailed structural basis and dynamics of the mitosin-kinetochore interaction. Two major regions important for targeting to centromeres were identified by analyzing different deletion mutants expressed in CHO cells: (i) the "core region" between amino acids 2792 and 2887, which was essential for the centromere localization of mitosin; and (ii) the internal repeats between residues 2094 and 2487, which cooperated with the core region to achieve strong mitosin-kinetochore interaction. The core region is characteristic of two leucine zipper motifs. Deletion of either motif abolished the centromere localization activity. In addition, Cys2864, adjacent to the second motif, was also essential for the activity of the core region. In contrast, the internal repeats alone were insufficient for centromere localization. We propose that this region may serve as a regulatory domain to facilitate interaction of the core region with the kinetochore. We showed that mitosin molecules entering nuclei after nuclear envelope breakdown (NEBD) were not assembled onto kinetochores efficiently, suggesting that the mitosin-kinetochore interaction is stabilized prior to NEBD. This result supports the idea of an ordered process for kinetochore assembly. Our data also suggest that mitosin might interact with chromatin in interphase. Evidence for coordinated regulation between the centromere-targeting and the putative chromatin-binding activities is also provided.
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Affiliation(s)
- X Zhu
- Shanghai Research Center of Life Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
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