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Luo J, Liu X. Polo-like kinase 1, on the rise from cell cycle regulation to prostate cancer development. Protein Cell 2012; 3:182-97. [PMID: 22447658 PMCID: PMC4875424 DOI: 10.1007/s13238-012-2020-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Accepted: 02/04/2012] [Indexed: 01/19/2023] Open
Abstract
Polo-like kinase 1 (Plk1), a well-characterized member of serine/threonine kinases Plk family, has been shown to play pivotal roles in mitosis and cytokinesis in eukaryotic cells. Recent studies suggest that Plk1 not only controls the process of mitosis and cytokinesis, but also, going beyond those previously described functions, plays critical roles in DNA replication and Pten null prostate cancer initiation. In this review, we briefly summarize the functions of Plk1 in mitosis and cytokinesis, and then mainly focus on newly discovered functions of Plk1 in DNA replication and in Pten-null prostate cancer initiation. Furthermore, we briefly introduce the architectures of human and mouse prostate glands and the possible roles of Plk1 in human prostate cancer development. And finally, the newly chemotherapeutic development of small-molecule Plk1 inhibitors to target Plk1 in cancer treatment and their translational studies are also briefly reviewed.
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Affiliation(s)
- Jijing Luo
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907 USA
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Ishibashi N, Kanamaru K, Ueno Y, Kojima S, Kobayashi T, Machida C, Machida Y. ASYMMETRIC-LEAVES2 and an ortholog of eukaryotic NudC domain proteins repress expression of AUXIN-RESPONSE-FACTOR and class 1 KNOX homeobox genes for development of flat symmetric leaves in Arabidopsis. Biol Open 2012; 1:197-207. [PMID: 23213410 PMCID: PMC3507280 DOI: 10.1242/bio.2012406] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Leaf primordia form around the shoot apical meristem, which consists of indeterminate stem cells. Upon initiation of leaf development, adaxial-abaxial patterning is crucial for appropriate lateral expansion, via cellular proliferation, and the formation of flat symmetric leaves. Many genes that specify such patterning have been identified, but regulation by upstream factors of the expression of relevant effector genes remains poorly understood. In Arabidopsis thaliana, ASYMMETRIC LEAVES2 (AS2) and AS1 play important roles in repressing transcription of class 1 KNOTTED1-like homeobox (KNOX) genes and leaf abaxial-determinant effector genes. We report here a mutation, designated enhancer of asymmetric leaves2 and asymmetric leaves1 (eal), that is associated with efficient generation of abaxialized filamentous leaves on the as2 or as1 background. Levels of transcripts of many abaxial-determinant genes, including ETTIN (ETT)/AUXIN RESPONSE FACTOR3 (ARF3), and all four class 1 KNOX genes were markedly elevated in as2 eal shoot apices. Rudimentary patterning in as2 eal leaves was suppressed by the ett mutation. EAL encodes BOBBER1 (BOB1), an Arabidopsis ortholog of eukaryotic NudC domain proteins. BOB1 was expressed in plant tissues with division potential and bob1 mutations resulted in lowered levels of transcripts of some cell-cycle genes and decreased rates of cell division in shoot and root apices. Coordinated cellular proliferation, supported by BOB1, and repression of all class 1 KNOX genes, ETT/ARF3 by AS2 (AS1) and BOB1 might be critical for repression of the indeterminate state and of aberrant abaxialization in the presumptive adaxial domain of leaf primordia, which might ensure the formation of flat symmetric leaves.
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Affiliation(s)
- Nanako Ishibashi
- Division of Biological Science, Graduate School of Science, Nagoya University , Chikusa-ku, Nagoya 464-8602 , Japan
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53
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The Polo-like kinase PLKA in Aspergillus nidulans is not essential but plays important roles during vegetative growth and development. EUKARYOTIC CELL 2011; 11:194-205. [PMID: 22140227 DOI: 10.1128/ec.05130-11] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Polo-like kinases (Plks) are conserved, multifunctional cell cycle regulators that are induced in many forms of cancer and play additional roles in metazoan development. We previously identified plkA in Aspergillus nidulans, the only Plk investigated in filamentous fungi to date, and partially characterized its function through overexpression. Here, we report the plkA null phenotype. Surprisingly, plkA was not essential, unlike Plks in other organisms that contain a single homologue. A subset of cells lacking PLKA contained defects in spindle formation and chromosome organization, supporting some conservation in cell cycle function. However, septa were present, suggesting that PLKA, unlike other Plks, is not a central regulator of septation. Colonies lacking PLKA were compact with multibranched hyphae, implying a role for this factor in aspects of hyphal morphogenesis. These defects were suppressed by high temperature or low concentrations of benomyl, suggesting that PLKA may function during vegetative growth by influencing microtubule dynamics. However, the colonies also showed reduced conidiation and precocious formation of sexual Hülle cells in a benomyl- and temperature-insensitive manner. This result suggests that PLKA may influence reproduction through distinct mechanisms and represents the first example of a link between Plk function and development in fungi. Finally, filamentous fungal Plks have distinct features, and phylogenetic analyses reveal that they may group more closely with metazoan PLK4. In contrast, yeast Plks are more similar to metazoan proteins PLK1 to PLK3. Thus, A. nidulans PLKA shows some conservation in cell cycle function but may also play novel roles during hyphal morphogenesis and development.
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54
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NudC is required for interkinetic nuclear migration and neuronal migration during neocortical development. Dev Biol 2011; 357:326-35. [PMID: 21771589 DOI: 10.1016/j.ydbio.2011.07.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/17/2011] [Accepted: 07/03/2011] [Indexed: 11/21/2022]
Abstract
NudC is a highly conserved protein necessary for cytoplasmic dynein-mediated nuclear migration in Aspergillus nidulans. NudC interacts genetically with Aspergillus NudF and physically with its mammalian orthologue Lis1, which is crucial for nuclear and neuronal migration during brain development. To test for related roles for NudC, we performed in utero electroporation into embryonic rat brain of cDNAs encoding shRNAs as well as wild-type and mutant forms of NudC. We show here that NudC, like Lis1, is required for neuronal migration during neocorticogenesis and we identify a specific role in apical nuclear migration in radial glial progenitor cells. These results identify a novel neuronal migration gene with a specific role in interkinetic nuclear migration, consistent with cytoplasmic dynein regulation.
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55
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Bahassi EM. Polo-like kinases and DNA damage checkpoint: beyond the traditional mitotic functions. Exp Biol Med (Maywood) 2011; 236:648-57. [PMID: 21558091 DOI: 10.1258/ebm.2011.011011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Polo-like kinases (Plks) are a family of serine-threonine kinases that play a pivotal role in cell cycle progression and in cellular response to DNA damage. The Plks are highly conserved from yeast to mammals. There are five Plk family members (Plk1-5) in humans, of which Plk1, is the best characterized. The Plk1 isoform is being aggressively pursued as a target for cancer therapy, following observations that this protein is overexpressed in human tumors and is actively involved in malignant transformation. The roles of Plks in mitotic entry, spindle pole functions and cytokinesis are well established and have been the subject of several recent reviews. In this review, we discuss functions of Plks other than their classical roles in mitotic progression. When cells incur DNA damage, they activate checkpoint mechanisms that result in cell cycle arrest and allow time for repair. If the damage is extensive and cannot be repaired, cells will undergo cell death by apoptosis. If the damage is repaired, cells can resume cycling, as part of the process known as checkpoint recovery. If the damage is not repaired or incompletely repaired, cells can override the checkpoint and resume cycling with damaged DNA, a process called checkpoint adaptation. The Plks play a role in all three outcomes and their involvement in these processes will be the subject of this review.
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Affiliation(s)
- El Mustapha Bahassi
- Division of Hematology and Oncology, Department of Internal Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267-0562, USA.
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56
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Zheng M, Cierpicki T, Burdette AJ, Utepbergenov D, Janczyk PŁ, Derewenda U, Stukenberg PT, Caldwell KA, Derewenda ZS. Structural features and chaperone activity of the NudC protein family. J Mol Biol 2011; 409:722-41. [PMID: 21530541 DOI: 10.1016/j.jmb.2011.04.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/07/2011] [Accepted: 04/07/2011] [Indexed: 11/19/2022]
Abstract
The NudC family consists of four conserved proteins with representatives in all eukaryotes. The archetypal nudC gene from Aspergillus nidulans is a member of the nud gene family that is involved in the maintenance of nuclear migration. This family also includes nudF, whose human orthologue, Lis1, codes for a protein essential for brain cortex development. Three paralogues of NudC are known in vertebrates: NudC, NudC-like (NudCL), and NudC-like 2 (NudCL2). The fourth distantly related member of the family, CML66, contains a NudC-like domain. The three principal NudC proteins have no catalytic activity but appear to play as yet poorly defined roles in proliferating and dividing cells. We present crystallographic and NMR studies of the human NudC protein and discuss the results in the context of structures recently deposited by structural genomics centers (i.e., NudCL and mouse NudCL2). All proteins share the same core CS domain characteristic of proteins acting either as cochaperones of Hsp90 or as independent small heat shock proteins. However, while NudC and NudCL dimerize via an N-terminally located coiled coil, the smaller NudCL2 lacks this motif and instead dimerizes as a result of unique domain swapping. We show that NudC and NudCL, but not NudCL2, inhibit the aggregation of several target proteins, consistent with an Hsp90-independent heat shock protein function. Importantly, and in contrast to several previous reports, none of the three proteins is able to form binary complexes with Lis1. The availability of structural information will be of help in further studies on the cellular functions of the NudC family.
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Affiliation(s)
- Meiying Zheng
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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57
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Chuang C, Lin SH, Huang F, Pan J, Josic D, Yu-Lee LY. Acetylation of RNA processing proteins and cell cycle proteins in mitosis. J Proteome Res 2011; 9:4554-64. [PMID: 20812760 DOI: 10.1021/pr100281h] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitosis is a highly regulated process in which errors can lead to genomic instability, a hallmark of cancer. During this phase of the cell cycle, transcription is silent and RNA translation is inhibited. Thus, mitosis is largely driven by post-translational modification of proteins, including phosphorylation, methylation, ubiquitination, and sumoylation. Here, we show that protein acetylation is prevalent during mitosis. To identify proteins that are acetylated, we synchronized HeLa cells in early prometaphase and immunoprecipitated lysine-acetylated proteins with antiacetyl-lysine antibody. The immunoprecipitated proteins were identified by LC-ESI-MS/MS analysis. These include proteins involved in RNA translation, RNA processing, cell cycle regulation, transcription, chaperone function, DNA damage repair, metabolism, immune response, and cell structure. Immunoprecipitation followed by Western blot analyses confirmed that two RNA processing proteins, eIF4G and RNA helicase A, and several cell cycle proteins, including APC1, anillin, and NudC, were acetylated in mitosis. We further showed that acetylation of APC1 and NudC was enhanced by apicidin treatment, suggesting that their acetylation was regulated by histone deacetylase. Moreover, treating mitotic cells with apicidin or trichostatin A induced spindle abnormalities and cytokinesis failure. These studies suggest that protein acetylation/deacetylation is likely an important regulatory mechanism in mitosis.
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Affiliation(s)
- Carol Chuang
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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58
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Studach L, Wang WH, Weber G, Tang J, Hullinger RL, Malbrue R, Liu X, Andrisani O. Polo-like kinase 1 activated by the hepatitis B virus X protein attenuates both the DNA damage checkpoint and DNA repair resulting in partial polyploidy. J Biol Chem 2010; 285:30282-93. [PMID: 20624918 PMCID: PMC2943266 DOI: 10.1074/jbc.m109.093963] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 07/09/2010] [Indexed: 01/21/2023] Open
Abstract
Hepatitis B virus X protein (pX), implicated in hepatocarcinogenesis, induces DNA damage because of re-replication and allows propagation of damaged DNA, resulting in partial polyploidy and oncogenic transformation. The mechanism by which pX allows cells with DNA damage to continue proliferating is unknown. Herein, we show pX activates Polo-like kinase 1 (Plk1) in the G(2) phase, thereby attenuating the DNA damage checkpoint. Specifically, in the G(2) phase of pX-expressing cells, the checkpoint kinase Chk1 was inactive despite DNA damage, and protein levels of claspin, an adaptor of ataxia telangiectasia-mutated and Rad3-related protein-mediated Chk1 phosphorylation, were reduced. Pharmacologic inhibition or knockdown of Plk1 restored claspin protein levels, Chk1 activation, and p53 stabilization. Also, protein levels of DNA repair protein Mre11 were decreased in the G(2) phase of pX-expressing cells but not with Plk1 knockdown. Interestingly, in pX-expressing cells, Mre11 co-immunoprecipitated with transfected Plk1 Polo-box domain, and inhibition of Plk1 increased Mre11 stability in cycloheximide-treated cells. These results suggest that pX-activated Plk1 by down-regulating Mre11 attenuates DNA repair. Importantly, concurrent inhibition of Plk1, p53, and Mre11 increased the number of pX-expressing cells with DNA damage entering mitosis, relative to Plk1 inhibition alone. By contrast, inhibition or knockdown of Plk1 reduced pX-induced polyploidy while increasing apoptosis. We conclude Plk1, activated by pX, allows propagation of DNA damage by concurrently attenuating the DNA damage checkpoint and DNA repair, resulting in polyploidy. We propose this novel Plk1 mechanism initiates pX-mediated hepatocyte transformation.
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Affiliation(s)
- Leo Studach
- From the Departments of Basic Medical Sciences and
| | | | - Gregory Weber
- Biochemistry, Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
| | - Jiabin Tang
- Biochemistry, Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
| | | | | | - Xiaoqi Liu
- Biochemistry, Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
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59
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Zhu XJ, Liu X, Jin Q, Cai Y, Yang Y, Zhou T. The L279P mutation of nuclear distribution gene C (NudC) influences its chaperone activity and lissencephaly protein 1 (LIS1) stability. J Biol Chem 2010; 285:29903-10. [PMID: 20675372 DOI: 10.1074/jbc.m110.105494] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
LIS1, a gene mutated in classical lissencephaly, plays essential roles in cytoplasmic dynein regulation, mitosis and cell migration. However, the regulation of LIS1 (lissencephaly protein 1) protein remains largely unknown. Genetic studies in Aspergillus nidulans have uncovered that the Nud (nuclear distribution) pathway is involved in the regulation of cytoplasmic dynein complex and a temperature-sensitive mutation in the nudC gene (L146P) greatly reduces the protein levels of NudF, an Aspergillus ortholog of LIS1. Here, we showed that L146 in Aspergillus NudC and its flanking region were highly conservative during evolution. The similar mutation in human NudC (L279P) obviously led to reduced LIS1 and cellular phenotypes similar to those of LIS1 down-regulation. To explore the underlying mechanism, we found that the p23 domain-containing protein NudC bound to the molecular chaperone Hsp90, which is also associated with LIS1. Inhibition of Hsp90 chaperone function by either geldanamycin or radicicol resulted in a decrease in LIS1 levels. Ectopic expression of Hsp90 partially reversed the degradation of LIS1 caused by overexpression of NudC-L279P. Furthermore, NudC was found to regulate the ATPase activity of Hsp90, which was repressed by the mutation of L279P. Interestingly, NudC itself was shown to possess a chaperone function, which also was suppressed by the L279P mutation. Together, these data suggest that NudC may be involved in the regulation of LIS1 stability by its chaperone function.
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Affiliation(s)
- Xiao-Jing Zhu
- Department of Cell Biology and Program in Molecular Cell Biology, Zhejiang University School of Medicine, Hangzhou 310058, China
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60
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Cytokinesis and cancer: Polo loves ROCK'n' Rho(A). J Genet Genomics 2010; 37:159-72. [PMID: 20347825 DOI: 10.1016/s1673-8527(09)60034-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 02/08/2010] [Accepted: 02/09/2010] [Indexed: 12/11/2022]
Abstract
Cytokinesis is the last step of the M (mitosis) phase, yet it is crucial for the faithful division of one cell into two. Cytokinesis failure is often associated with cancer. Cytokinesis can be morphologically divided into four steps: cleavage furrow initiation, cleavage furrow ingression, midbody formation and abscission. Molecular studies have revealed that RhoA as well as its regulators and effectors are important players to ensure a successful cytokinesis. At the same time, Polo-like kinase 1 (Plk1) is an important kinase that can target many substrates and carry out different functions during mitosis, including cytokinesis. Recent studies are beginning to unveil a closer tie between Plk1 and RhoA networks. More specifically, Plk1 phosphorylates the centralspindlin complex Cyk4 and MKLP1/CHO1, thus recruiting RhoA guanine nucleotide-exchange factor (GEF) Ect2 through its phosphopeptide-binding BRCT domains. Ect2 itself can be phosphorylated by Plk1 in vitro. Plk1 can also phosphorylate another GEF MyoGEF to regulate RhoA activity. Once activated, RhoA-GTP will activate downstream effectors, including ROCK1 and ROCK2. ROCK2 is among the proteins that associate with Plk1 Polo-binding domain (PBD) in a large proteomic screen, and Plk1 can phosphorylate ROCK2 in vitro. We review current understandings of the interplay between Plk1, RhoA proteins and other proteins (e.g., NudC, MKLP2, PRC1, CEP55) involved in cytokinesis, with particular emphasis of its clinical implications in cancer.
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61
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Park JE, Soung NK, Johmura Y, Kang YH, Liao C, Lee KH, Park CH, Nicklaus MC, Lee KS. Polo-box domain: a versatile mediator of polo-like kinase function. Cell Mol Life Sci 2010; 67:1957-70. [PMID: 20148280 PMCID: PMC2877763 DOI: 10.1007/s00018-010-0279-9] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 01/13/2010] [Accepted: 01/19/2010] [Indexed: 12/23/2022]
Abstract
Members of the polo subfamily of protein kinases have emerged as important regulators in diverse aspects of the cell cycle and cell proliferation. A large body of evidence suggests that a highly conserved polo-box domain (PBD) present in the C-terminal non-catalytic region of polo kinases plays a pivotal role in the function of these enzymes. Recent advances in our comprehension of the mechanisms underlying mammalian polo-like kinase 1 (Plk1)-dependent protein-protein interactions revealed that the PBD serves as an essential molecular mediator that brings the kinase domain of Plk1 into proximity with its substrates, mainly through phospho-dependent interactions with its target proteins. In this review, current understanding of the structure and functions of PBD, mode of PBD-dependent interactions and substrate phosphorylation, and other phospho-independent functions of PBD are discussed.
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Affiliation(s)
- Jung-Eun Park
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bldg. 37, Rm. 3118, Bethesda, MD 20892-4258 USA
| | - Nak-Kyun Soung
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bldg. 37, Rm. 3118, Bethesda, MD 20892-4258 USA
| | - Yoshikazu Johmura
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bldg. 37, Rm. 3118, Bethesda, MD 20892-4258 USA
| | - Young H. Kang
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bldg. 37, Rm. 3118, Bethesda, MD 20892-4258 USA
| | - Chenzhong Liao
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, MD 21702 USA
| | - Kyung H. Lee
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bldg. 37, Rm. 3118, Bethesda, MD 20892-4258 USA
| | - Chi Hoon Park
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bldg. 37, Rm. 3118, Bethesda, MD 20892-4258 USA
| | - Marc C. Nicklaus
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, MD 21702 USA
| | - Kyung S. Lee
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bldg. 37, Rm. 3118, Bethesda, MD 20892-4258 USA
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62
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NudC-like protein 2 regulates the LIS1/dynein pathway by stabilizing LIS1 with Hsp90. Proc Natl Acad Sci U S A 2010; 107:3499-504. [PMID: 20133715 DOI: 10.1073/pnas.0914307107] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The type I lissencephaly gene product LIS1, a key regulator of cytoplasmic dynein, is critical for cell proliferation, survival, and neuronal migration. However, little is known about the regulation of LIS1. Here, we identify a previously uncharacterized mammalian homolog of Aspergillus NudC, NudCL2 (NudC-like protein 2), as a regulator of LIS1. NudCL2 is localized to the centrosome in interphase, and spindle poles and kinetochores during mitosis, a pattern similar to the localization of LIS1 and cytoplasmic dynein. Depletion of NudCL2 destabilized LIS1 and led to phenotypes resembling those of either dynein or LIS1 deficiency. NudCL2 complexed with and enhanced the interaction between LIS1 and Hsp90. Either disruption of the LIS1-Hsp90 interaction with the C terminus of NudCL2 or inhibition of Hsp90 chaperone function by geldanamycin decreased LIS1 stability. Thus, our results suggest that NudCL2 regulates the LIS1/dynein pathway by stabilizing LIS1 with Hsp90 chaperone. This represents a hitherto undescribed mechanism of the LIS1/dynein regulation in mammalian cells.
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63
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Andrysik Z, Bernstein WZ, Deng L, Myer DL, Li YQ, Tischfield JA, Stambrook PJ, Bahassi EM. The novel mouse Polo-like kinase 5 responds to DNA damage and localizes in the nucleolus. Nucleic Acids Res 2010; 38:2931-43. [PMID: 20100802 PMCID: PMC2875007 DOI: 10.1093/nar/gkq011] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Polo-like kinases (Plk1-4) are emerging as an important class of proteins involved in many aspects of cell cycle regulation and response to DNA damage. Here, we report the cloning of a fifth member of the polo-like kinase family named Plk5. DNA and protein sequence analyses show that Plk5 shares more similarities with Plk2 and Plk3 than with Plk1 and Plk4. Consistent with this observation, we show that mouse Plk5 is a DNA damage inducible gene. Mouse Plk5 protein localizes predominantly to the nucleolus, and deletion of a putative nucleolus localization signal (NoLS) within its N-terminal moiety disrupts its nucleolar localization. Ectopic expression of Plk5 leads to cell cycle arrest in G1, decreased DNA synthesis, and to apoptosis, a characteristic it shares with Plk3. Interestingly, in contrast to mouse Plk5 gene, the sequence of human Plk5 contains a stop codon that produces a truncated protein lacking part of the kinase domain.
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Affiliation(s)
- Zdenek Andrysik
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
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64
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Lu H, Lou DH, Zhu LL. Real-time fluorescent quantitative polymerase chain reaction study of polo-like kinase-1 in pterygia. J Int Med Res 2009; 37:1851-8. [PMID: 20146883 DOI: 10.1177/147323000903700621] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
This study was designed to examine the expression of polo-like kinase 1 (PLK1) mRNA in 16 pterygia and 13 normal conjunctival tissue specimens using real-time fluorescent quantitative polymerase chain reaction (PCR). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as the housekeeping gene. The difference in threshold cycle value (DeltaC(t)) was derived for PLK1 and GAPDH for each sample assayed, and the difference between the paired samples (DeltaDeltaC(t)) was calculated. The mean +/- SD DeltaC(t) of PLK1 mRNA was 9.56 +/- 1.30 in pterygia compared with 10.71 +/- 1.39 in normal conjunctiva. The expression of PLK1 mRNA in pterygium was 2.08 - 2.36 times that in normal conjunctiva; this difference was statistically significant. Real-time fluorescent quantitative PCR analysis appears to be effective and sensitive when determining the level of PLK1 mRNA expression. Using this method, it was demonstrated that PLK1 mRNA is over-expressed in pterygia, indicating a probable role for PLK1 in their development.
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Affiliation(s)
- H Lu
- Department of Ophthalmology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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65
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Inhibition of cytokinesis by overexpression of NudCL that is localized to the centrosome and midbody. Cell Res 2009; 19:1305-8. [DOI: 10.1038/cr.2009.118] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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66
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Li L, Wang X, Chen J, Ding H, Zhang Y, Hu TC, Hu LH, Jiang HL, Shen X. The natural product Aristolactam AIIIa as a new ligand targeting the polo-box domain of polo-like kinase 1 potently inhibits cancer cell proliferation. Acta Pharmacol Sin 2009; 30:1443-53. [PMID: 19801998 PMCID: PMC4007328 DOI: 10.1038/aps.2009.141] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 08/19/2009] [Indexed: 11/09/2022] Open
Abstract
AIM To search for novel inhibitors of human polo-like kinase 1 (Plk1), which plays important roles in various aspects of mitotic progression and is believed as a promising anti-cancer drug target, and further investigate the potential inhibition mechanism of active compounds against Plk1, thus developing potent anti-tumor lead compounds. METHODS Surface plasmon resonance (SPR) technology-based assay and enzymatic inhibition assay were used to screen Plk1 inhibitors. Sulphorhodamine B (SRB)-based assay, flow cytometry, confocal microscopy and Western blotting were used to further identify the potent Plk1 inhibitor. To investigate the inhibitory mechanism of the active compound against Plk1, enzymatic inhibition assay, SPR and yeast two-hybrid technology-based assays were used. RESULTS Aristolactam AIIIa was identified as a new type of Plk1 inhibitors, targeting the Polo Box domain (PBD) which is another efficient tactic for exploring Plk1 inhibitors. Further studies indicated that it could block the proliferations of HeLa, A549, HGC and the HCT-8/V cells (clinical Navelbine-resistant cancer cell), induce mitotic arrest of HeLa cells at G2/M phase with spindle abnormalities and promote apoptosis in HeLa cells. The results from SPR and yeast two-hybrid technology-based assays suggested that it could target both the catalytic domain of Plk1 (CD) and PBD and enhance the CD/PBD interaction. CONCLUSION Our current work is expected to shed light on the potential anti-tumor mechanism of Aristolactam AIIIa, and this natural product might be possibly used as a lead compound for further developing anti-tumor drugs.
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Affiliation(s)
- Li Li
- School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Xu Wang
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Jing Chen
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Hong Ding
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Yu Zhang
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Tian-cen Hu
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Li-hong Hu
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Hua-liang Jiang
- School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xu Shen
- School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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67
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He ZL, Zheng H, Lin H, Miao XY, Zhong DW. Overexpression of polo-like kinase1 predicts a poor prognosis in hepatocellular carcinoma patients. World J Gastroenterol 2009; 15:4177-82. [PMID: 19725153 PMCID: PMC2738815 DOI: 10.3748/wjg.15.4177] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2009] [Revised: 08/05/2009] [Accepted: 08/12/2009] [Indexed: 02/06/2023] Open
Abstract
AIM To elucidate the role of overexpressed polo-like kinase1 (PLK1) in hepatocellular carcinoma (HCC). METHODS We prospectively collected clinicopathological, immunohistochemical and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) data from 135 HCC patients undergoing successful hepatectomy. The correlations between PLK1 mRNA expression and clinicopathologic variables were analyzed by Mann-Whitney U test. Prognostic factors were identified by univariate and multivariate analyses. RESULTS Immunohistochemical results showed overexpression of PLK1 was mainly found in tumor tissues compared with tumor-free tissue. A similar mRNA result was obtained by semi-quantitative RT-PCR. A total of 111 samples were positive for PLK1 mRNA expression. The positive expression was correlated with venous invasion, tumor nodules and Edmondson grade. Furthermore, 1, 3, 5-year survival rates in the positive expression group were significantly lower than the negative control group. Multivariate analysis showed that positive PLK1 expression was an independent risk factor for HCC. CONCLUSION PLK1 could be a potential biomarker for diagnosis and therapy for HCC.
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68
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Riera J, Lazo PS. The mammalian NudC-like genes: a family with functions other than regulating nuclear distribution. Cell Mol Life Sci 2009; 66:2383-90. [PMID: 19381437 PMCID: PMC11115750 DOI: 10.1007/s00018-009-0025-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 02/25/2009] [Accepted: 03/24/2009] [Indexed: 10/20/2022]
Abstract
Nuclear distribution gene C homolog (NudC) is a highly conserved gene. It has been identified in different species from fungi to mammals. The high degree of conservation, in special in the nudC domain, suggests that they are genes with essential functions. Most of the identified genes in the family have been implicated in cell division through the regulation of cytoplasmic dynein. As for mammalian genes, human NUDC has been implicated in the migration and proliferation of tumor cells and has therefore been considered a possible therapeutic target. There is evidence suggesting that mammalian NudC is also implicated in the regulation of the inflammatory response and in thrombopoiesis. The presence of these other functions not related to the interaction with molecular motors agrees with that these genes and their products are larger in size than their microbial orthologous, indicating that they have evolved to convey additional features.
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Affiliation(s)
- José Riera
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo, Campus del Cristo, 33071 Oviedo, Spain
| | - Pedro S. Lazo
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo, Campus del Cristo, 33071 Oviedo, Spain
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69
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Faircloth LM, Churchill PF, Caldwell GA, Caldwell KA. The microtubule-associated protein, NUD-1, exhibits chaperone activity in vitro. Cell Stress Chaperones 2009; 14:95-103. [PMID: 18626791 PMCID: PMC2673900 DOI: 10.1007/s12192-008-0061-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Accepted: 06/23/2008] [Indexed: 10/21/2022] Open
Abstract
Regulation of cell division requires the concerted function of proteins and protein complexes that properly mediate cytoskeletal dynamics. NudC is an evolutionarily conserved protein of undetermined function that associates with microtubules and interacts with several key regulators of mitosis, such as polo-kinase 1 (Plk1) and dynein. NudC is essential for proper mitotic progression, and homologs have been identified in species ranging from fungi to humans. In this paper, we report the characterization of the Caenorhabditis elegans NudC homolog, NUD-1, as a protein exhibiting molecular chaperone activity. All NudC/NUD-1 proteins share a conserved p23/HSP20 domain predicted by three-dimensional modeling [Garcia-Ranea, Mirey, Camonis, Valencia, FEBS Lett 529(2-3):162-167, 2002]. We demonstrate that nematode NUD-1 is able to prevent the aggregation of two substrate proteins, citrate synthase (CS) and luciferase, at stoichiometric concentrations. Further, NUD-1 also protects the native state of CS from thermal inactivation by significantly reducing the inactivation rate of this enzyme. To further determine if NUD-1/substrate complexes were productive or simply "dead-end" unfolding intermediates, a luciferase refolding assay was utilized. Following thermal denaturation, rabbit reticulocyte lysate and ATP were added and luciferase activity measured. In the presence of NUD-1, nearly all of the luciferase activity was regained, indicating that unfolded intermediates complexed with NUD-1 could be refolded. These studies represent the first functional evidence for a member of this mitotically essential protein family as having chaperone activity and facilitates elucidation of the role such proteins play in chaperone complexes utilized in cell division. C. elegans NUD-1 is a member of an evolutionary conserved protein family of unknown function involved in the regulation of cytoskeletal dynamics. NUD-1 and its mammalian homolog, NudC, function with the dynein motor complex to ensure proper cell division, and knockdown or overexpression of these proteins leads to disruption of mitosis. In this paper, we show that NUD-1 possesses ATP-independent chaperone activity comparable to that of small heat shock proteins and cochaperones and that changes in phosphorylation state functionally alter chaperone activity in a phosphomimetic NUD-1 mutant.
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Affiliation(s)
- Lindsay M. Faircloth
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487 USA
| | - Perry F. Churchill
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487 USA
| | - Guy A. Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487 USA
- Departments of Neurology and Neurobiology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, AL 35294 USA
| | - Kim A. Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487 USA
- Departments of Neurology and Neurobiology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, AL 35294 USA
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Asiedu M, Wu D, Matsumura F, Wei Q. Phosphorylation of MyoGEF on Thr-574 by Plk1 promotes MyoGEF localization to the central spindle. J Biol Chem 2008; 283:28392-400. [PMID: 18694934 PMCID: PMC2568926 DOI: 10.1074/jbc.m801801200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 08/05/2008] [Indexed: 01/13/2023] Open
Abstract
We reported previously that a guanine nucleotide exchange factor, MyoGEF, localizes to the central spindle, activates RhoA, and is required for cytokinesis. In this study, we have found that Plk1 (polo-like kinase 1) can phosphorylate MyoGEF, thereby recruiting MyoGEF to the central spindle as well as enhancing MyoGEF activity toward RhoA. The in vitro kinase assay shows that Plk1 can phosphorylate MyoGEF on threonine 574. Immunoprecipitation/immunoblot analysis demonstrates that mutation of threonine 574 to alanine dramatically decreases threonine phosphorylation of MyoGEF in transfected HeLa cells, suggesting that threonine 574 is phosphorylated in vivo. Consistent with these observations, immunofluorescence shows that Plk1 and MyoGEF colocalize at the spindle pole and central spindle during mitosis and cytokinesis. Importantly, RNA interference-mediated depletion of Plk1 interferes with the localization of MyoGEF at the spindle pole and central spindle. Moreover, mutation of threonine 574 to alanine in MyoGEF or depletion of Plk1 by RNA interference leads to a decrease in MyoGEF activity toward RhoA in HeLa cells. Therefore, our results suggest that Plk1 can regulate MyoGEF activity and localization, contributing to the regulation of cytokinesis.
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Affiliation(s)
- Michael Asiedu
- Department of Biochemistry, Kansas State University, Manhattan, Kansas 66506, USA
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71
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Fu Z, Malureanu L, Huang J, Wang W, Li H, van Deursen JM, Tindall DJ, Chen J. Plk1-dependent phosphorylation of FoxM1 regulates a transcriptional programme required for mitotic progression. Nat Cell Biol 2008; 10:1076-82. [PMID: 19160488 PMCID: PMC2882053 DOI: 10.1038/ncb1767] [Citation(s) in RCA: 275] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Proper control of entry into and progression through mitosis is essential for normal cell proliferation and the maintenance of genome stability. The mammalian mitotic kinase Polo-like kinase 1 (Plk1) is involved in multiple stages of mitosis5. Here we report that Forkhead Box M1 (FoxM1), a substrate of Plk1, controls a transcriptional programme that mediates Plk1-dependent regulation of cell-cycle progression. The carboxy-terminal domain of FoxM1 binds Plk1, and phosphorylation of two key residues in this domain by Cdk1 is essential for Plk1-FoxM1 interaction. Formation of the Plk1-FoxM1 complex allows for direct phosphorylation of FoxM1 by Plk1 at G2/M and the subsequent activation of FoxM1 activity, which is required for expression of key mitotic regulators, including Plk1 itself. Thus, Plk1-dependent regulation of FoxM1 activity provides a positive-feedback loop ensuring tight regulation of transcriptional networks essential for orderly mitotic progression.
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Affiliation(s)
- Zheng Fu
- Department of Urology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
| | - Liviu Malureanu
- Department of Pediatrics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
| | - Jun Huang
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520-8040, USA
| | - Wei Wang
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Hao Li
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Jan M. van Deursen
- Department of Pediatrics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
| | - Donald J. Tindall
- Department of Urology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
| | - Junjie Chen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520-8040, USA
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Helmstaedt K, Laubinger K, Vosskuhl K, Bayram O, Busch S, Hoppert M, Valerius O, Seiler S, Braus GH. The nuclear migration protein NUDF/LIS1 forms a complex with NUDC and BNFA at spindle pole bodies. EUKARYOTIC CELL 2008; 7:1041-52. [PMID: 18390647 PMCID: PMC2446659 DOI: 10.1128/ec.00071-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 03/25/2008] [Indexed: 11/20/2022]
Abstract
Nuclear migration depends on microtubules, the dynein motor complex, and regulatory components like LIS1 and NUDC. We sought to identify new binding partners of the fungal LIS1 homolog NUDF to clarify its function in dynein regulation. We therefore analyzed the association between NUDF and NUDC in Aspergillus nidulans. NUDF and NUDC directly interacted in yeast two-hybrid experiments via NUDF's WD40 domain. NUDC-green fluorescent protein (NUDC-GFP) was localized to immobile dots in the cytoplasm and at the hyphal cortex, some of which were spindle pole bodies (SPBs). We showed by bimolecular fluorescence complementation microscopy that NUDC directly interacted with NUDF at SPBs at different stages of the cell cycle. Applying tandem affinity purification, we isolated the NUDF-associated protein BNFA (for binding to NUDF). BNFA was dispensable for growth and for nuclear migration. GFP-BNFA fusions localized to SPBs at different stages of the cell cycle. This localization depended on NUDF, since the loss of NUDF resulted in the cytoplasmic accumulation of BNFA. BNFA did not bind to NUDC in a yeast two-hybrid assay. These results show that the conserved NUDF and NUDC proteins play a concerted role at SPBs at different stages of the cell cycle and that NUDF recruits additional proteins specifically to the dynein complex at SPBs.
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Affiliation(s)
- Kerstin Helmstaedt
- Molekulare Mikrobiologie und Genetik, Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Grisebachstrasse 8, D-37077 Göttingen, Germany
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73
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Liu L, Zhang M, Zou P. Expression of PLK1 and survivin in non-Hodgkin's lymphoma treated with CHOP. Acta Pharmacol Sin 2008; 29:371-5. [PMID: 18298903 DOI: 10.1111/j.1745-7254.2008.00750.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
AIM The present study was designed to investigate the expression of Polo-like kinase 1 (PLK1) and survivin in non-Hodgkinos lymphoma (NHL). METHODS The expression of PLK1 and survivin were detected with immunohistochemical techniques. RESULTS The expression rate of PLK1 and survivin were 63.6% (56/88) and 79.5% (70/88) in NHL, respectively. PLK1 expression correlated with systemic symptoms, lactate dehydrogenase levels, and international prognostic index scores in B-NHL and T-NHL, while survivin did not. CONCLUSION PLK1 and survivin are both overexpressed in NHL. There is a significant relationship between the overexpression of PLK1 and clinical features.
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Affiliation(s)
- Lin Liu
- Department of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Nishi Y, Rogers E, Robertson SM, Lin R. Polo kinases regulate C. elegans embryonic polarity via binding to DYRK2-primed MEX-5 and MEX-6. Development 2008; 135:687-97. [PMID: 18199581 DOI: 10.1242/dev.013425] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Polo kinases are known key regulators of cell divisions. Here we report a novel, non-cell division function for polo kinases in embryonic polarity of newly fertilized Caenorhabditis elegans embryos. We show that polo kinases, via their polo box domains, bind to and regulate the activity of two key polarity proteins, MEX-5 and MEX-6. These polo kinases are asymmetrically localized along the anteroposterior axis of newly fertilized C. elegans embryos in a pattern identical to that of MEX-5 and MEX-6. This asymmetric localization of polo kinases depends on MEX-5 and MEX-6, as well as genes regulating MEX-5 and MEX-6 asymmetry. We identify an amino acid of MEX-5, T(186), essential for polo binding and show that T(186) is important for MEX-5 function in vivo. We also show that MBK-2, a developmentally regulated DYRK2 kinase activated at meiosis II, primes T(186) for subsequent polo kinase-dependent phosphorylation. Prior phosphorylation of MEX-5 at T(186) greatly enhances phosphorylation of MEX-5 by polo kinases in vitro. Our results provide a mechanism by which MEX-5 and MEX-6 function is temporally regulated during the crucial oocyte-to-embryo transition.
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Affiliation(s)
- Yuichi Nishi
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
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75
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Fink J, Sanders K, Rippl A, Finkernagel S, Beckers TL, Schmidt M. Cell type-- dependent effects of Polo-like kinase 1 inhibition compared with targeted polo box interference in cancer cell lines. Mol Cancer Ther 2007; 6:3189-97. [PMID: 18089713 DOI: 10.1158/1535-7163.mct-07-0048] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Multiple critical roles within mitosis have been assigned to Polo-like kinase 1 (Plk1), making it an attractive candidate for mitotic targeting of cancer cells. Plk1 contains two domains amenable for targeted interference: a kinase domain responsible for the enzymatic function and a polo box domain necessary for substrate recognition and subcellular localization. Here, we compare two approaches for targeted interference with Plk1 function, either by a Plk1 small-molecule enzyme inhibitor or by inducible overexpression of the polo box in human cancer cell lines. Inducible expression of the Plk1 polo box resulted in growth inhibition of RKOp27 human colon adenocarcinoma cells without obvious signs of mitotic abnormalities. A Plk1 kinase inhibitor in the same cell line arrested cells in mitosis with subsequent onset of apoptosis. Similarly, PC-3 human prostate cancer cells were growth inhibited on expression of the polo box. Prolonged expression of the polo box in these cells resulted in the occurrence of binucleated or multinucleated cells. In contrast, U2OS human osteosarcoma cells responded to overexpression of the polo box with a massive mitotic accumulation coinciding with the onset of apoptosis. Comparison of spindle formation revealed very similar mitotic abnormalities in polo box-overexpressing U2OS cells compared with U2OS cells treated with the Plk1 kinase inhibitor. We conclude that interference with polo box function and inhibition of Plk1 kinase activity can exert very similar phenotypic effects in certain cell lines but highly contrasting effects in others. This may point to subtle differences in the molecular machinery of mitosis regulation in cancer cells.
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Affiliation(s)
- Jenny Fink
- Nycomed GmbH, RPD/SO, Byk-Gulden-Strasse 2, D-78467 Konstanz, Germany.
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Abstract
Polo-like kinase 1 (PLK1) belongs to a conservative family of serine/threonine kinase and plays an important role in the process of cell cycle. Survivin is a member of inhibitor of apoptosis protein (IAP) family. We investigated the expression of PLK1 and survivin with immunohistochemical techniques in diffuse large B-cell lymphoma (DLBCL) and assessed their significance as a potent new tumor marker. The expression rate of PLK1 and survivin were 66.7% (26/39) and 82.1% (32/39), respectively. PLK1 expression correlated with systemic symptom, LDH level, IPI scores and therapeutic effect in DLBCL, while survivin did not. PLK1 expression correlated with shortened event-free survival (EFS) using the Log-rank test in DLBCL, but survivin did not. Cox regression analysis identified the independent prognostic significance for PLK1. The results suggest that there is a significant relationship between over expression of PLK1, the clinical features and survival time. Compared with survivin, PLK1 seems to be a better independent prognostic factor for DLBCL.
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Affiliation(s)
- Lin Liu
- Department of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Riera J, Rodríguez R, Carcedo MT, Campa VM, Ramos S, Lazo PS. Isolation and characterization ofnudCfrom mouse macrophages, a gene implicated in the inflammatory response through the regulation of PAF-AH(I) activity. FEBS Lett 2007; 581:3057-62. [PMID: 17555748 DOI: 10.1016/j.febslet.2007.05.065] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Accepted: 05/17/2007] [Indexed: 10/23/2022]
Abstract
We report the characterization of a cDNA induced in mouse macrophages that encodes a 332-amino acid protein with extensive sequence identity with members of the mammalian nudC-like genes. The interaction between mNUDC and the regulatory beta subunit of platelet activating factor acetylhydrolase I (PAF-AH(I)) shown in this article indicates a new function of NUDC. Thus, we show that NUDC increases the catalytic activity of PAF-AH(I) and that this regulatory activity is located in the carboxyl terminal half of the protein which is highly conserved. This suggests a novel function for mammalian nudC-like genes as anti-inflammatory proteins.
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Affiliation(s)
- José Riera
- Departamento de Bioquímica y Biología Molecular and Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo, 33071 Oviedo, Spain
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Lowery DM, Clauser KR, Hjerrild M, Lim D, Alexander J, Kishi K, Ong SE, Gammeltoft S, Carr SA, Yaffe MB. Proteomic screen defines the Polo-box domain interactome and identifies Rock2 as a Plk1 substrate. EMBO J 2007; 26:2262-73. [PMID: 17446864 PMCID: PMC1864981 DOI: 10.1038/sj.emboj.7601683] [Citation(s) in RCA: 195] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2006] [Accepted: 03/14/2007] [Indexed: 11/09/2022] Open
Abstract
Polo-like kinase-1 (Plk1) phosphorylates a number of mitotic substrates, but the diversity of Plk1-dependent processes suggests the existence of additional targets. Plk1 contains a specialized phosphoserine-threonine binding domain, the Polo-box domain (PBD), postulated to target the kinase to its substrates. Using the specialized PBD of Plk1 as an affinity capture agent, we performed a screen to define the mitotic Plk1-PBD interactome by mass spectrometry. We identified 622 proteins that showed phosphorylation-dependent mitosis-specific interactions, including proteins involved in well-established Plk1-regulated processes, and in processes not previously linked to Plk1 such as translational control, RNA processing, and vesicle transport. Many proteins identified in our screen play important roles in cytokinesis, where, in mammalian cells, the detailed mechanistic role of Plk1 remains poorly defined. We go on to characterize the mitosis-specific interaction of the Plk1-PBD with the cytokinesis effector kinase Rho-associated coiled-coil domain-containing protein kinase 2 (Rock2), demonstrate that Rock2 is a Plk1 substrate, and show that Rock2 colocalizes with Plk1 during cytokinesis. Finally, we show that Plk1 and RhoA function together to maximally enhance Rock2 kinase activity in vitro and within cells, and implicate Plk1 as a central regulator of multiple pathways that synergistically converge to regulate actomyosin ring contraction during cleavage furrow ingression.
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Affiliation(s)
- Drew M Lowery
- Departments of Biology and Biological Engineering, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Majbrit Hjerrild
- Departments of Biology and Biological Engineering, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Clinical Biochemistry, Glostrup Hospital, Glostrup, Denmark
| | - Dan Lim
- Departments of Biology and Biological Engineering, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jes Alexander
- Departments of Biology and Biological Engineering, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kazuhiro Kishi
- Departments of Biology and Biological Engineering, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shao-En Ong
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Steen Gammeltoft
- Department of Clinical Biochemistry, Glostrup Hospital, Glostrup, Denmark
| | - Steven A Carr
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Michael B Yaffe
- Departments of Biology and Biological Engineering, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
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79
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Petronczki M, Glotzer M, Kraut N, Peters JM. Polo-like kinase 1 triggers the initiation of cytokinesis in human cells by promoting recruitment of the RhoGEF Ect2 to the central spindle. Dev Cell 2007; 12:713-25. [PMID: 17488623 DOI: 10.1016/j.devcel.2007.03.013] [Citation(s) in RCA: 225] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 03/07/2007] [Accepted: 03/19/2007] [Indexed: 11/24/2022]
Abstract
Cytokinesis of animal cells requires ingression of the actomyosin-based contractile ring between segregated sister genomes. Localization of the RhoGEF Ect2 to the central spindle at anaphase promotes local activation of the RhoA GTPase, which induces assembly and ingression of the contractile ring. Here we have used BI 2536, an inhibitor of the mitotic kinase Plk1, to analyze the functions of this enzyme during late mitosis in human cells. We show that Plk1 acts after Cdk1 inactivation and independently from Aurora B to promote RhoA accumulation at the equator, contractile ring formation, and cleavage furrow ingression. Inhibition of Plk1 abolishes the interaction of Ect2 with its activator and midzone anchor, HsCyk-4, thereby preventing localization of Ect2 to the central spindle. We propose that late mitotic Plk1 activity promotes recruitment of Ect2 to the central spindle, triggering the initiation of cytokinesis and contributing to cleavage plane specification in human cells.
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Affiliation(s)
- Mark Petronczki
- Research Institute of Molecular Pathology, A-1030 Vienna, Austria
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80
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Te J, Jia L, Rogers J, Miller A, Hartson SD. Novel subunits of the mammalian Hsp90 signal transduction chaperone. J Proteome Res 2007; 6:1963-73. [PMID: 17348703 DOI: 10.1021/pr060595i] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
As one of the major cellular chaperones, Hsp90 plays diverse roles in supporting and regulating wild-type and oncogenic signal transduction proteins. Hsp90 function itself is regulated by its various nonsubstrate subunits. To define Hsp90's predominant in vivo functions and the mechanisms for regulating this function, the human Hsp90 interactome was characterized using gel-based proteomics techniques. Results show that Hsp90's most prominent association is its previously described interaction with Hsp70, a primary chaperone capable of recognizing and binding hydrophobic peptide segments. Additionally, novel human proteins discovered in this study reveal that several newly described Hsp90 associations in yeast are conserved in the human cytoplasm. Additionally, other new Hsp90 subunits imply that a great deal of Hsp90 function may be directed to the assembly, regulation, or exploitation of the tubulin-based cytoskeleton network, particularly the mitotic spindle.
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Affiliation(s)
- Jeannie Te
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma 74078-3035, USA
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81
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Lansing TJ, McConnell RT, Duckett DR, Spehar GM, Knick VB, Hassler DF, Noro N, Furuta M, Emmitte KA, Gilmer TM, Mook RA, Cheung M. In vitro biological activity of a novel small-molecule inhibitor of polo-like kinase 1. Mol Cancer Ther 2007; 6:450-9. [PMID: 17267659 DOI: 10.1158/1535-7163.mct-06-0543] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Polo-like kinase 1 (PLK1) plays key roles in the regulation of mitotic progression, including mitotic entry, spindle formation, chromosome segregation, and cytokinesis. PLK1 expression and activity are strongly linked to proliferating cells. Many studies have shown that PLK1 expression is elevated in a variety of tumors, and high expression often correlates with poor prognosis. Using a variety of methods, including small-molecule inhibition of PLK1 function and/or activity, apoptosis in cancer cell lines, cell cycle arrest in normal cell lines, and antitumor activity in vivo have been observed. In the present study, we have examined the in vitro biological activity of a novel and selective thiophene benzimidazole ATP-competitive inhibitor of PLK1 and PLK3 (5-(5,6-dimethoxy-1H-benzimidazol-1-yl)-3-{[2-(trifluoromethyl)-benzyl]oxy}thiophene-2-carboxamide, called compound 1). Compound 1 has low nanomolar activity against the PLK1 and PLK3 enzymes and potently inhibits the proliferation of a wide variety of tumor cell lines. In the lung adenocarcinoma cell line NCI-H460, compound 1 induces a transient G(2)-M arrest, mitotic spindle defects, and a multinucleate phenotype resulting in apoptosis, whereas normal human diploid fibroblasts arrest in G(2)-M and show little apoptosis. We also describe a cellular mechanistic assay that was developed to identify potent intracellular inhibitors of PLK1. In addition to its potential as a therapeutic agent for treating cancer, compound 1 is also a useful tool molecule for further investigation of the biological functions of PLK1 and PLK3.
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Affiliation(s)
- Timothy J Lansing
- GlaxoSmithKline R & D, 5 Moore Drive, Research Triangle Park, NC 27709, USA.
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82
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Junaid A, Moon MC, Harding GEJ, Zahradka P. Osteopontin localizes to the nucleus of 293 cells and associates with polo-like kinase-1. Am J Physiol Cell Physiol 2007; 292:C919-26. [PMID: 17005603 DOI: 10.1152/ajpcell.00477.2006] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Osteopontin (OPN) is a secreted phosphoprotein involved in cellular proliferation and associated with tumor progression. Although an intracellular form of OPN has been described, its function remains unknown. In this study, a novel nuclear location for intracellular OPN and a correlation with cell division were demonstrated. OPN distinctly localized to the nucleus in a subset of transiently transfected human embryonic kidney 293 cells. Immunoblotting confirmed the nuclear location of native OPN, and results from immunofluorescence studies suggested an association between nuclear OPN and cell cycle progression. Flow cytometry revealed that nuclear and cellular OPN content rose significantly during the S and G(2)/M phases, respectively. Treatment of cells with the DNA polymerase inhibitor aphidicolin prevented cell cycling and greatly reduced cellular OPN content. The intracellular location of OPN coincided with polo-like kinase-1 (Plk-1), a member of the polo-like kinase family, which, in part through their regulation of centrosome-related events, are integral to successful cellular mitosis. OPN and Plk-1 were coimmunoprecipitated from nuclear, but not cystoslic, extracts, demonstrating an interaction that is limited to the nucleus, presumably during mitosis. Deletion of the COOH terminus of OPN militated against nuclear localization and Plk-1 interaction. Elevated expression of OPN was also associated with an increase in the number of multinucleate 293 cells, whereas transfection of the COOH-terminal-deleted OPN decreased the percentage of multinucleate cells below basal levels. These findings implicate intranuclear OPN as a participant in the process of cell duplication.
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Affiliation(s)
- Asad Junaid
- Grace General Hospital, 4W-300 Booth Dr., Winnipeg, MB, Canada.
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83
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Jang YJ, Ji JH, Choi YC, Ryu CJ, Ko SY. Regulation of Polo-like kinase 1 by DNA damage in mitosis. Inhibition of mitotic PLK-1 by protein phosphatase 2A. J Biol Chem 2007; 282:2473-82. [PMID: 17121863 DOI: 10.1074/jbc.m605480200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA damage triggers multiple checkpoint pathways to arrest cell cycle progression. Polo-like kinase 1 (Plk1) is an important regulator of several events during mitosis. In addition to Plk1 functions in cell cycle, Plk1 is involved in DNA damage check-point in G2 phase. Normally, ataxia telangiectasia-mutated kinase (ATM) is a key enzyme involved in G2 phase cell cycle arrest following DNA damage, and inhibition of Plk1 by DNA damage during G2 occurs in a ATM/ATR-dependent manner. However, it is still unclear how Plk1 is regulated in response to DNA damage in mitosis in which Plk1 is already activated. Here, we show that treatment of mitotic cells with doxorubicin and gamma-irradiation inhibits Plk1 activity through dephosphorylation of Plk1, and cells were arrested in G2 phase. Treatments of the phosphatase inhibitors and siRNA experiments suggested that PP2A pathway might be involved in regulating mitotic Plk1 activity in mitotic DNA damage. Finally, we propose a novel pathway, which is connected between ATM/ATR/Chk and protein phosphatase-Plk1 in DNA damage response in mitosis.
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Affiliation(s)
- Young-Joo Jang
- Laboratory of Biochemistry, The School of Dentistry, Dankook University, 29 Anseo-Dong, Cheonan, 330-714, Korea.
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84
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Ji JH, Jang YJ. Screening of domain-specific target proteins of polo-like kinase 1: construction and application of centrosome/kinetochore-specific targeting peptide. JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2006; 39:709-16. [PMID: 17129406 DOI: 10.5483/bmbrep.2006.39.6.709] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mammalian polo-like kinase 1 (Plk1) acts at various stages in early and late mitosis. Plk1 localizes at the centrosome and maintains this position through mitosis. Thereafter Plk1 moves to the kinetochore and midbody region, important sites during chromosome separation and cytokinesis. The catalytic domain of Plk1 is in the Nterminus region, whereas the non-catalytic region in the Cterminus of Plk1 has a conserved motif, named the Polobox. This motif is critical for Plk localization. EGFP proteins fused with the N-terminus and C-terminus of Plk1 localize in the nucleus and centrosomes, respectively. The core sequences of the polo-box (50 amino acids) also localize in Plk1 target organelles. To screen for domainspecific target proteins of Plk1, we constructed an Nterminal domain and a tandem repeat polo-box motif, and used them as templates in a yeast two-hybrid screen. The HeLa cell cDNA library indicated several proteins including the centrosome/kinetochore components or regulators, to be characterized as positive clones. Through in vitro protein binding analyses, we confirmed an interaction between these proteins and Plk1. The data reported from this study indicate that the N- and Ctermini of Plk1 may function through recruitment and/or activation of domain-specific target proteins in dividing cells. Additionally, tandem repeats of the conserved core motif of the polo-box are sufficient for targeting and may be useful as a centrosome/kinetochore-specific targeting peptide.
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Affiliation(s)
- Jae-Hoon Ji
- Laboratory of Biochemistry, The School of Dentistry, Dankook University, 29 Anseo-Dong, Cheonan-Si, Chungnam 330-714, Korea
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85
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Feng Y, Yuan JH, Maloid SC, Fisher R, Copeland TD, Longo DL, Conrads TP, Veenstra TD, Ferris A, Hughes S, Dimitrov DS, Ferris DK. Polo-like kinase 1-mediated phosphorylation of the GTP-binding protein Ran is important for bipolar spindle formation. Biochem Biophys Res Commun 2006; 349:144-52. [PMID: 16930555 DOI: 10.1016/j.bbrc.2006.08.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Accepted: 08/03/2006] [Indexed: 01/21/2023]
Abstract
Polo-like kinase functions are essential for the establishment of a normal bipolar mitotic spindle, although precisely how Plk1 regulates the spindle is uncertain. In this study, we report that the small GTP/GDP-binding protein Ran is associated with Plk1. Plk1 is capable of phosphorylating co-immunoprecipitated Ran in vitro on serine-135 and Ran is phosphorylated in vivo at the same site during mitosis when Plk1 is normally activated. Cell cultures over-expressing a Ran S135D mutant have significantly higher numbers of abnormal mitotic cells than those over-expressing either wild-type or S135A Ran. The abnormalities in S135D mutant cells are similar to cells over-expressing Plk1. Our data suggests that Ran is a physiological substrate of Plk1 and that Plk1 regulates the spindle organization partially through its phosphorylation on Ran.
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Affiliation(s)
- Yang Feng
- Laboratory of Cancer Prevention, NCI at Frederick, Frederick, MD, USA; Nanobiology Program, CCR, NCI at Frederick, Frederick, MD, USA.
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86
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Qi W, Tang Z, Yu H. Phosphorylation- and polo-box-dependent binding of Plk1 to Bub1 is required for the kinetochore localization of Plk1. Mol Biol Cell 2006; 17:3705-16. [PMID: 16760428 PMCID: PMC1525235 DOI: 10.1091/mbc.e06-03-0240] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Accepted: 05/31/2006] [Indexed: 11/11/2022] Open
Abstract
Polo-like kinase 1 (Plk1) is required for the generation of the tension-sensing 3F3/2 kinetochore epitope and facilitates kinetochore localization of Mad2 and other spindle checkpoint proteins. Here, we investigate the mechanism by which Plk1 itself is recruited to kinetochores. We show that Plk1 binds to budding uninhibited by benzimidazole 1 (Bub1) in mitotic human cells. The Plk1-Bub1 interaction requires the polo-box domain (PBD) of Plk1 and is enhanced by cyclin-dependent kinase 1 (Cdk1)-mediated phosphorylation of Bub1 at T609. The PBD-dependent binding of Plk1 to Bub1 facilitates phosphorylation of Bub1 by Plk1 in vitro. Depletion of Bub1 in HeLa cells by RNA interference (RNAi) diminishes the kinetochore localization of Plk1. Ectopic expression of the wild-type Bub1, but not the Bub1-T609A mutant, in Bub1-RNAi cells restores the kinetochore localization of Plk1. Our results suggest that phosphorylation of Bub1 at T609 by Cdk1 creates a docking site for the PBD of Plk1 and facilitates the kinetochore recruitment of Plk1.
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Affiliation(s)
- Wei Qi
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX 75390-9041
| | - Zhanyun Tang
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX 75390-9041
| | - Hongtao Yu
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX 75390-9041
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87
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Nishino M, Kurasawa Y, Evans R, Lin SH, Brinkley BR, Yu-Lee LY. NudC is required for Plk1 targeting to the kinetochore and chromosome congression. Curr Biol 2006; 16:1414-21. [PMID: 16860740 DOI: 10.1016/j.cub.2006.05.052] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/05/2006] [Accepted: 05/17/2006] [Indexed: 01/01/2023]
Abstract
The equal distribution of chromosomes during mitosis is critical for maintaining the integrity of the genome. Essential to this process are the capture of spindle microtubules by kinetochores and the congression of chromosomes to the metaphase plate . Polo-like kinase 1 (Plk1) is a mitotic kinase that has been implicated in microtubule-kinetochore attachment, tension generation at kinetochores, tension-responsive signal transduction, and chromosome congression . The tension-sensitive substrates of Plk1 at the kinetochore are unknown. Here, we demonstrate that human Nuclear distribution protein C (NudC), a 42 kDa protein initially identified in Aspergillus nidulans and shown to be phosphorylated by Plk1 , plays a significant role in regulating kinetochore function. Plk1-phosphorylated NudC colocalizes with Plk1 at the outer plate of the kinetochore. Depletion of NudC reduced end-on microtubule attachments at kinetochores and resulted in defects in chromosome congression at the metaphase plate. Importantly, NudC-deficient cells exhibited mislocalization of Plk1 and the Kinesin-7 motor CENP-E from prometaphase kinetochores. Ectopic expression of wild-type NudC, but not NudC containing mutations in the Plk1 phosphorylation sites, recovered Plk1 localization at the kinetochore and rescued chromosome congression. Thus, NudC functions as both a substrate and a spatial regulator of Plk1 at the kinetochore to promote chromosome congression.
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Affiliation(s)
- Michiya Nishino
- Program in Cell and Molecular Biology, Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
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88
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Zhou T, Zimmerman W, Liu X, Erikson RL. A mammalian NudC-like protein essential for dynein stability and cell viability. Proc Natl Acad Sci U S A 2006; 103:9039-44. [PMID: 16754861 PMCID: PMC1482562 DOI: 10.1073/pnas.0602916103] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytoplasmic dynein, a minus-end-directed microtubule motor, has been implicated in many fundamental cellular processes; however, little is known regarding the underlying molecular machinery that regulates its stability. In Aspergillus nidulans, nuclear distribution gene C (nudC) has been implicated in the regulation of dynein-mediated nuclear migration. Here, we characterize a previously undescribed mammalian NudC-like protein (NudCL). The expression and phosphorylation of NudCL are increased during mitosis. Depletion of NudCL by RNA interference in HeLa cells inhibits cell growth and induces mitotic arrest with multiple mitotic defects, which subsequently result in cell death. Unexpectedly, the majority of NudCL depletion-induced mitotic defects may result from loss of dynein function; this interpretation is supported by the failure to recruit sufficient gamma-tubulin to spindle poles and the mislocalization of the dynein complex from kinetochores, spindle microtubules, and spindle poles during mitosis. Depletion of NudCL also results in the aggregation of dynein intermediate chain throughout the cytoplasm during mitosis. NudCL was shown to bind to the dynein complex, and its depletion induces degradation of dynein intermediate chain, a process suppressed by MG132, a proteasome inhibitor. Taken together, these data suggest a previously undescribed mechanism whereby NudCL appears to influence the stabilization of dynein intermediate chain.
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Affiliation(s)
- Tianhua Zhou
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Wendy Zimmerman
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Xiaoqi Liu
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Raymond L. Erikson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
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89
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Jiang N, Wang X, Jhanwar-Uniyal M, Darzynkiewicz Z, Dai W. Polo box domain of Plk3 functions as a centrosome localization signal, overexpression of which causes mitotic arrest, cytokinesis defects, and apoptosis. J Biol Chem 2006; 281:10577-82. [PMID: 16478733 DOI: 10.1074/jbc.m513156200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Polo-like kinase 3 (Plk3), an immediate early response gene product, plays an important role in the regulation of mitosis, DNA damage checkpoint activation, and Golgi dynamics. Similar to other members of the Plk family, Plk3 has a conserved kinase domain at the N terminus and a Polo box domain consisting of two Polo boxes at the C terminus. In this study, we demonstrate that the Polo box domain of Plk3 is sufficient for subcellular localization of this kinase to the centrosomes, the spindle poles, and the midbody when ectopically expressed in HeLa and U2OS cells. Both Polo boxes are required for the subcellular localization. Overexpression of the Polo box domain, not the kinase domain, of Plk3 causes significant cell cycle arrest and cytokinesis defects, eventually leading to mitotic catastrophe/apoptosis. Interestingly, the Polo box domain of Plk3 is more potent in inhibiting cell proliferation and inducing apoptosis than that of Plk1, suggesting that this domain can provide an additional structural basis for discovery of new anticancer drugs given the current emphasis on Plk1 as a therapeutic target.
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Affiliation(s)
- Ning Jiang
- Division of Molecular Carcinogenesis, Department of Medicine, New York Medical College, Basic Science Building, Valhalla, NY 10595, USA
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90
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Weichert W, Ullrich A, Schmidt M, Gekeler V, Noske A, Niesporek S, Buckendahl AC, Dietel M, Denkert C. Expression patterns of polo-like kinase 1 in human gastric cancer. Cancer Sci 2006; 97:271-6. [PMID: 16630118 PMCID: PMC11159179 DOI: 10.1111/j.1349-7006.2006.00170.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Polo-like kinase 1 (PLK1) is centrally involved in the regulation of mitosis in normal and malignant cells. It is known that inhibition of PLK1 expression in vitro and in vivo leads to mitotic arrest, induction of apoptosis and suppression of tumor growth. In the present study, expression of PLK1 was investigated in paraffin tissue of 135 cases of gastric adenocarcinoma and in 46 corresponding lymph node metastases by immunohistochemistry. Expression data were correlated with clinicopathological parameters and patient survival. Seventy-three (54.1%) of 135 carcinomas showed an overexpression of PLK1 compared to normal gastric mucosa. Overexpression of PLK1 correlated positively with tumor stage, nodal status and diffuse growth pattern. PLK1 expression in the primary tumor did not differ from PLK1 expression in the corresponding lymph node metastases. PLK1 expression was a significant prognostic factor in univariate but not in multivariate survival analysis. As a conclusion, upregulated PLK1 expression in gastric cancer correlates with a malignant tumor phenotype and has impact on patient prognosis. These data underscore the importance of PLK1 in gastric carcinogenesis and present a translational link for functional data into potential clinical use by defining PLK1 as an attractive protein for novel targeted chemotherapeutic approaches in gastric cancer.
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Affiliation(s)
- Wilko Weichert
- Institut für Pathologie, Charité Universitätsmedizin, Schumannstrasse 20/21, 10117 Berlin, Germany.
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91
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Schmidt M, Hofmann HP, Sanders K, Sczakiel G, Beckers TL, Gekeler V. Molecular alterations after Polo-like kinase 1 mRNA suppression versus pharmacologic inhibition in cancer cells. Mol Cancer Ther 2006; 5:809-17. [PMID: 16648550 DOI: 10.1158/1535-7163.mct-05-0455] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Multiple roles within mitosis have been assigned to Polo-like kinase 1 (Plk1), making it an attractive candidate for mitotic targeting of cancer cells. We have employed chimeric antisense oligonucleotides to investigate the molecular alterations after targeted interference with Plk1 in RKO human colon adenocarcinoma and PC3 prostate cancer cells. Suppression of Plk1 mRNA resulted in a dramatic increase of the mitotic index followed by the onset of apoptosis. Mitotically arrested cells displayed randomly separated condensed chromosomes and the occurrence of multiple spindle poles with well-formed asters. Induction of apoptosis was strictly dependent on cell cycle progression: Genetically engineered RKO cells with inducible expression of the cyclin-dependent kinase inhibitor p27(Kip1) were completely refractory to Plk1 depletion-induced apoptosis when they were arrested in the G1 phase of the cell cycle. Various mitotic markers, including MPM-2, cdc25c, cyclin B1, or phosphorylated histone H3, were investigated to explore the molecular consequences of Plk1 depletion. Whereas most marker proteins showed similar alterations compared with treatment with paclitaxel, cdc25c was fully phosphorylated solely in paclitaxel-treated cells but only partially phosphorylated in Plk1-depleted cells, although both treatments caused a profound mitotic arrest. This differential phosphorylation of cdc25c was used to test whether a pharmacologic inhibitor of Plk1 would exert the same cellular effects as interference with Plk1 on a mRNA level. It was found that the differential electrophoretic mobility of cdc25c can serve as a reliable molecular marker to track inhibition of Plk1 by small-molecule inhibitors within a cell.
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Affiliation(s)
- Mathias Schmidt
- Therapeutic Area Oncology, ALTANA Pharma AG, Byk-Gulden-Str. 2, D-78467 Konstanz, Germany.
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92
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Abstract
Human polo-like kinase 1 (PLK1) is essential during mitosis and in the maintenance of genomic stability. PLK1 is overexpressed in human tumours and has prognostic potential in cancer, indicating its involvement in carcinogenesis and its potential as a therapeutic target. The use of different PLK1 inhibitors has increased our knowledge of mitotic regulation and allowed us to assess their ability to suppress tumour growth in vivo. We address the structural features of the kinase domain and the unique polo-box domain of PLK1 that are most suited for drug development and discuss our current understanding of the therapeutic potential of PLK1.
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Affiliation(s)
- Klaus Strebhardt
- Department of Obstetrics and Gynecology, School of Medicine, J.W. Goethe-University, Theodore-Stern-Kai 7, 60590 Frankfurt, Germany.
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93
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Lingle WL, Lukasiewicz K, Salisbury JL. Deregulation of the centrosome cycle and the origin of chromosomal instability in cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 570:393-421. [PMID: 18727509 DOI: 10.1007/1-4020-3764-3_14] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although we have begun to tap into the mechanisms behind Boveri's initial observation that supernumerary centrosomes cause chromosome missegregation in sea urchin eggs, there is still much left to discover with regard to chromosomal instability in cancer. Many of the molecular players involved in regulation of the centrosome and cell cycles, and the coupling of the two cycles to produce a bipolar mitotic spindle have been identified. One theme that has become apparent is that cross talk and interrelatedness of the pathways serve to provide redundant mechanisms to maintain genomic integrity. In spite of this, cells occasionally fall prey to insults that initiate and maintain the chromosomal instability that results in viable malignant tumours. Deregulation of centrosome structure is an integral aspect of the origin of chromosomal instability in many cancers. There are numerous routes to centrosome amplification including: environmental insults such as ionising radiation and exposure to estrogen (Li et al., 2005); failure of cytokinesis; and activating mutations in key regulators of centrosome structure and function. There are two models for initiation of centrosome amplification (Figure 2). In the first, centrosome duplication and chromosome replication remain coupled and cells enter G2 with 4N chromosomes and duplicated centrosomes. However, these cells may fail to complete mitosis, and thus reenter G1 as tetraploid cells with amplified centrosomes. In the second, the centrosome cycle is uncoupled from chromosome replication and cells go through one or more rounds of centriole/centrosome duplication in the absence of chromosome replication. If these cells then go through chromosome replication accompanied by another round of centrosome duplication, cells complete G2 with 4N chromosomes and more than 2 centrosomes, and therefore are predisposed to generate multipolar mitotic spindles. Fragmentation of centrosomes due to ionising radiation is a variation of the second model. Once centrosome amplification is present, even in a diploid cell, that cell has the potential to yield viable aneuploid progeny. The telophase cell in Figure 3C illustrates this scenario. In a normal telophase configuration, the total number of chromosomes is 92 (resulting from the segregation of 46 pairs of chromatids), with each daughter nucleus containing 46 individual chromosomes. Based on the number of kinetochore signals present, the lower nucleus in Figure 3C has approximately 28 chromosomes, and the elongate upper nucleus has approximately 60, for a total of 88. Due to superimposition of kinetochores in this maximum projection image, 88 is an underestimate of the actual number of kinetochores and is not significantly different from the expected total of 92. A cell resulting from the lower nucleus with only around 28 chromosomes would probably not be viable, much as Boveri's experiments indicated. However, the upper nucleus with at least 60 chromosomes could be viable. This cell would enter G1 as hypotriploid (69 chromosomes = triploid) with 2 centrosomes. During S and G2, the centrosomes and chromosomes would double, and the following mitosis could be tetrapolar with a 6N chromosome content. When centrosome amplification is accompanied by permissive lapses in cell cycle checkpoints, the potential for malignant growth is present. These lapses could result from specific genetic mutations and amplifications, epigenetic gene silencing, or from massive chromosomal instability caused by the centrosome amplification. Centrosome amplification, therefore, can serve to exacerbate and/or generate genetic instabilities associated with cancers.
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Affiliation(s)
- Wilma L Lingle
- Mayo Clinic College of Medicine, Mayo Clinic Foundation, Mayo Clinic Cancer Center, Rochester, Minnesota 55905, USA
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94
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Chen XH, Lan B, Qu Y, Zhang XQ, Cai Q, Liu BY, Zhu ZG. Inhibitory effect of Polo-like kinase 1 depletion on mitosis and apoptosis of gastric cancer cells. World J Gastroenterol 2006; 12:29-35. [PMID: 16440413 PMCID: PMC4077490 DOI: 10.3748/wjg.v12.i1.29] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 05/28/2005] [Accepted: 06/11/2005] [Indexed: 02/06/2023] Open
Abstract
AIM Polo-like kinase 1 (PLK1) serine/threonine kinase plays a vital role in multiple phases of mitosis in gastric cancer cells. To investigate the effect of PLK1 depletion on mitosis and apoptosis of gastric cancer cells. METHODS PLK1 expression was blocked by small RNA interference(siRNA). The expression levels of PLK1, cdc2, cyclin B and caspase 3 were detected by Western blotting. Then, PLK1 depletion, cdc2 activity, cell proliferation, cell cycle phase distribution, mitotic spindle structure, and the rate of apoptosis of the PLK1 knockdown cells were observed. RESULTS PLK1 gene knockdown was associated with increased cyclin B expression, increased cdc2 activity (but not with the expression levels), accumulation of gastric cancer cells at G2/M, improper mitotic spindle formation, delayed chromosome separation and delayed or arrested cytokinesis. Moreover, PLK1 depletion in gastric cancer cells was associated with decreased proliferation, attenuated pro-caspase 3 levels and increased apoptosis. CONCLUSION Blockage of PLK1 expression may lead to decreased mitosis or even apoptosis in gastric cancer cells, indicating that PLK1 may be a valuable therapeutic target for gastric cancer.
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Affiliation(s)
- Xue-Hua Chen
- Department of Surgery, Shanghai Institute of Digestive Surgery, Ruijin Hospital, Medical School of Shanghai Jiao Tong University, Shanghai 200025 China
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95
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Miserey-Lenkei S, Couëdel-Courteille A, Del Nery E, Bardin S, Piel M, Racine V, Sibarita JB, Perez F, Bornens M, Goud B. A role for the Rab6A' GTPase in the inactivation of the Mad2-spindle checkpoint. EMBO J 2006; 25:278-89. [PMID: 16395330 PMCID: PMC1383512 DOI: 10.1038/sj.emboj.7600929] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Accepted: 11/30/2005] [Indexed: 12/21/2022] Open
Abstract
The two isoforms of the Rab6 GTPase, Rab6A and Rab6A', regulate a retrograde transport route connecting early endosomes and the endoplasmic reticulum via the Golgi complex in interphasic cells. Here we report that when Rab6A' function is altered cells are unable to progress normally through mitosis. Such cells are blocked in metaphase, despite displaying a normal Golgi fragmentation and with the Mad2-spindle checkpoint activated. Furthermore, the Rab6 effector p150(Glued), a subunit of the dynein/dynactin complex, remains associated with some kinetochores. A similar phenotype was observed when GAPCenA, a GTPase-activating protein of Rab6, was depleted from cells. Our results suggest that Rab6A' likely regulates the dynamics of the dynein/dynactin complex at the kinetochores and consequently the inactivation of the Mad2-spindle checkpoint. Rab6A', through its interaction with p150(Glued) and GAPCenA, may thus participate in a pathway involved in the metaphase/anaphase transition.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Bruno Goud
- UMR 144 CNRS/IC, Institut Curie, Paris, France
- UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. Tel.: +33 1 4234 6398; Fax: +33 1 4234 6382; E-mail:
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96
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Bal HP, Cheng J, Murakami A, Tallarico ASC, Wang W, Zhou D, Vasicek TJ, Marasco WA. GITR overexpression on CD4+CD25+ HTLV-1 transformed cells: detection by massively parallel signature sequencing. Biochem Biophys Res Commun 2005; 332:569-84. [PMID: 15896717 DOI: 10.1016/j.bbrc.2005.04.162] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Accepted: 04/26/2005] [Indexed: 10/25/2022]
Abstract
HTLV-I is the etiologic agent of adult T-cell leukemia (ATL), a fatal T-cell malignancy that is associated with profound immunosuppression. In this study, comprehensive gene expression profiling was performed using massively parallel signature sequencing (MPSS) to investigate virus-host interactions in acutely HTLV-1 transformed cells. The analysis revealed the modulation of numerous genes across different functional classes, many of which have not been previously implicated in HTLV-1 transformation or ATL. Differences in the transcriptomes of transformed cell lines were observed that have provided clues on how different clonal populations of cells respond to virus transformation. Quantitation of HTLV-1 transcription was possible, thus making MPSS a useful tool to study emerging pathogens and unknown microbial causes of human diseases. Importantly, overexpression of GITR, an activation marker that has not been previously reported to be upregulated by HTLV-1-infection or in transformed/leukemic cells and that is associated with the suppressor phenotype of CD4+CD25+ regulatory T-cells (Tregs), was also observed. The deep and quantitative gene expression profile generated by MPSS should provide additional leads for discovery research that can be applied to better understand the pathobiology of HTLV-1 transformation and ATL as well as to developing new therapies.
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Affiliation(s)
- Harshawardhan P Bal
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney St., Boston, MA 02115, USA
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97
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Li S, Oakley CE, Chen G, Han X, Oakley BR, Xiang X. Cytoplasmic dynein's mitotic spindle pole localization requires a functional anaphase-promoting complex, gamma-tubulin, and NUDF/LIS1 in Aspergillus nidulans. Mol Biol Cell 2005; 16:3591-605. [PMID: 15930134 PMCID: PMC1182300 DOI: 10.1091/mbc.e04-12-1071] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In Aspergillus nidulans, cytoplasmic dynein and NUDF/LIS1 are found at the spindle poles during mitosis, but they seem to be targeted to this location via different mechanisms. The spindle pole localization of cytoplasmic dynein requires the function of the anaphase-promoting complex (APC), whereas that of NUDF does not. Moreover, although NUDF's localization to the spindle poles does not require a fully functional dynein motor, the function of NUDF is important for cytoplasmic dynein's targeting to the spindle poles. Interestingly, a gamma-tubulin mutation, mipAR63, nearly eliminates the localization of cytoplasmic dynein to the spindle poles, but it has no apparent effect on NUDF's spindle pole localization. Live cell analysis of the mipAR63 mutant revealed a defect in chromosome separation accompanied by unscheduled spindle elongation before the completion of anaphase A, suggesting that gamma-tubulin may recruit regulatory proteins to the spindle poles for mitotic progression. In A. nidulans, dynein is not apparently required for mitotic progression. In the presence of a low amount of benomyl, a microtubule-depolymerizing agent, however, a dynein mutant diploid strain exhibits a more pronounced chromosome loss phenotype than the control, indicating that cytoplasmic dynein plays a role in chromosome segregation.
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Affiliation(s)
- Shihe Li
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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98
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Abstract
Phosphorylation by protein kinases is the most widespread and well-studied signaling mechanism in eukaryotic cells. Phosphorylation can regulate almost every property of a protein and is involved in all fundamental cellular processes. Cataloging and understanding protein phosphorylation is no easy task: many kinases may be expressed in a cell, and one-third of all intracellular proteins may be phosphorylated, representing as many as 20,000 distinct phosphoprotein states. Defining the kinase complement of the human genome, the kinome, has provided an excellent starting point for understanding the scale of the problem. The kinome consists of 518 kinases, and every active protein kinase phosphorylates a distinct set of substrates in a regulated manner. Deciphering the complex network of phosphorylation-based signaling is necessary for a thorough and therapeutically applicable understanding of the functioning of a cell in physiological and pathological states. We review contemporary techniques for identifying physiological substrates of the protein kinases and studying phosphorylation in living cells.
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Affiliation(s)
- Sam A Johnson
- Molecular and Cell Biology Laboratory, Salk Institute, 10010 North Torrey Pines Road, La Jolla, California 92037, USA
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99
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Abstract
Research in different species has shown that Polo-like kinases are essential for successful cell division. In human cells, Polo-like kinase-1 (Plk1) has been implicated in the regulation of different processes, including mitotic entry, spindle formation and cytokinesis. Recently, a range of new downstream targets of Plk1 has been identified, as well as a molecular mechanism that explains recruitment of Plk1 to potential substrate proteins through its polo-box domain. On the basis of these reports, we discuss possible mechanisms by which Polo-like kinases can exert their multiple functions during mitosis. Polo-like kinases also function in DNA damage checkpoints. Plk1 has been shown to be a target of the G2 DNA damage checkpoint, while Cdc5, the Polo-like kinase in Saccharomyces cerevisiae, has long been known to be required for adaptation to persistent DNA damage. Just recently, a similar requirement for Polo-like kinases during checkpoint adaptation was demonstrated in multicellular organisms. Moreover, Plk1 was also shown to be required for checkpoint recovery following checkpoint inactivation, that is, in cells where the damage is completely repaired. Thus, Plk1 appears to play a role at multiple points during a restart of the cell cycle following DNA damage. Based on these novel observations, we discuss possible consequences of using Plk1 as a target in anticancer strategies.
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Affiliation(s)
- Marcel A T M van Vugt
- Division of Molecular Biology H8, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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100
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van de Weerdt BCM, van Vugt MATM, Lindon C, Kauw JJW, Rozendaal MJ, Klompmaker R, Wolthuis RMF, Medema RH. Uncoupling anaphase-promoting complex/cyclosome activity from spindle assembly checkpoint control by deregulating polo-like kinase 1. Mol Cell Biol 2005; 25:2031-44. [PMID: 15713655 PMCID: PMC549351 DOI: 10.1128/mcb.25.5.2031-2044.2005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Revised: 06/14/2004] [Accepted: 11/24/2004] [Indexed: 01/25/2023] Open
Abstract
Polo-like kinase 1 (Plk1) plays a role in numerous events in mitosis, but how the multiple functions of Plk1 are separated is poorly understood. We studied regulation of Plk1 through two putative phosphorylation residues, Ser-137 and Thr-210. Using phospho-specific antibodies, we found that Thr-210 phosphorylation precedes Ser-137 phosphorylation in vivo, the latter occurring specifically in late mitosis. We show that expression of two activating mutants of these residues, S137D and T210D, results in distinct mitotic phenotypes. Whereas expression of both phospho-mimicking mutants as well as of the double mutant leads to accelerated mitotic entry, further progression through mitosis is dramatically different: the T210D mutant causes a spindle assembly checkpoint-dependent delay, whereas the expression of the S137D mutant or the double mutant results in untimely activation of the anaphase-promoting complex/cyclosome (APC/C) and frequent mitotic catastrophe. Using nonphosphorylatable Plk1-S137A and Plk1-T210A mutants, we show that both sites contribute to proper mitotic progression. Based on these observations, we propose that Plk1 function is altered at different stages of mitosis through consecutive posttranslational events, e.g., at Ser-137 and Thr-210. Furthermore, our data show that uncontrolled Plk1 activation can uncouple APC/C activity from spindle assembly checkpoint control.
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