1
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Huang SK, Rubinstein JL, Kay LE. Cryo-EM of the Nucleosome Core Particle Bound to Ran-RCC1 Reveals a Dynamic Complex. Biochemistry 2024; 63:880-892. [PMID: 38501608 DOI: 10.1021/acs.biochem.3c00724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Ras-related nuclear protein (Ran) is a member of the Ras superfamily of small guanosine triphosphatases (GTPases) and a regulator of multiple cellular processes. In healthy cells, the GTP-bound form of Ran is concentrated at chromatin, creating a Ran•GTP gradient that provides the driving force for nucleocytoplasmic transport, mitotic spindle assembly, and nuclear envelope formation. The Ran•GTP gradient is maintained by the regulator of chromatin condensation 1 (RCC1), a guanine nucleotide exchange factor that accelerates GDP/GTP exchange in Ran. RCC1 interacts with nucleosomes, which are the fundamental repeating units of eukaryotic chromatin. Here, we present a cryo-EM analysis of a trimeric complex composed of the nucleosome core particle (NCP), RCC1, and Ran. While the contacts between RCC1 and Ran in the complex are preserved compared with a previously determined structure of RCC1-Ran, our study reveals that RCC1 and Ran interact dynamically with the NCP and undergo rocking motions on the nucleosome surface. Furthermore, the switch 1 region of Ran, which plays an important role in mediating conformational changes associated with the substitution of GDP and GTP nucleotides in Ras family members, appears to undergo disorder-order transitions and forms transient contacts with the C-terminal helix of histone H2B. Nucleotide exchange assays performed in the presence and absence of NCPs are not consistent with an active role for nucleosomes in nucleotide exchange, at least in vitro. Instead, the nucleosome stabilizes RCC1 and serves as a hub that concentrates RCC1 and Ran to promote efficient Ran•GDP to Ran•GTP conversion.
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Affiliation(s)
- Shuya Kate Huang
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Chemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Hospital for Sick Children, Program in Molecular Medicine, Toronto, ON M5G 1X8, Canada
| | - John L Rubinstein
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Hospital for Sick Children, Program in Molecular Medicine, Toronto, ON M5G 1X8, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Lewis E Kay
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Chemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Hospital for Sick Children, Program in Molecular Medicine, Toronto, ON M5G 1X8, Canada
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2
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An X, Zhao S, Luo X, Chen C, Liu T, Li W, Zou L, Sun C. Genome-wide identification and expression analysis of the regulator of chromosome condensation 1 gene family in wheat ( Triticum aestivum L.). FRONTIERS IN PLANT SCIENCE 2023; 14:1124905. [PMID: 36909424 PMCID: PMC9998523 DOI: 10.3389/fpls.2023.1124905] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
Wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD) is the world's most widely cultivated crop and an important staple food for humans, accounting for one-fifth of calories consumed. Proteins encoded by the regulator of chromosome condensation 1 (RCC1) are highly conserved among eukaryotes and consist of seven repeated domains that fold into a seven-bladed propeller structure. In this study, a total of 76 RCC1 genes of bread wheat were identified via a genome-wide search, and their phylogenetic relationship, gene structure, protein-conserved domain, chromosome localization, conserved motif, and transcription factor binding sites were systematically analyzed using the bioinformatics approach to indicate the evolutionary and functional features of these genes. The expression patterns of 76 TaRCC1 family genes in wheat under various stresses were further analyzed, and RT-PCR verified that RCC1-3A (TraesCS3A02G362800), RCC1-3B (TraesCS3B02G395200), and RCC1-3D (TraesCS3D02G35650) were significantly induced by salt, cold, and drought stresses. Additionally, the co-expression network analysis and binding site prediction suggested that Myb-7B (TraesCS7B02G188000) and Myb-7D (TraesCS7D02G295400) may bind to the promoter of RCC1-3A/3B and upregulate their expression in response to abiotic stresses in wheat. The results have furthered our understanding of the wheat RCC1 family members and will provide important information for subsequent studies and the use of RCC1 genes in wheat.
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Affiliation(s)
- Xia An
- Zhejiang Xiaoshan Institute of Cotton and Bast Fiber Crops, Zhejiang Institute of Landscape Plants and Flowers, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Shuqi Zhao
- Cotton and Wheat Research Institute, Huanggang Academy of Agricultural Sciences, Huanggang, China
| | - Xiahong Luo
- Zhejiang Xiaoshan Institute of Cotton and Bast Fiber Crops, Zhejiang Institute of Landscape Plants and Flowers, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Changli Chen
- Zhejiang Xiaoshan Institute of Cotton and Bast Fiber Crops, Zhejiang Institute of Landscape Plants and Flowers, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Tingting Liu
- Zhejiang Xiaoshan Institute of Cotton and Bast Fiber Crops, Zhejiang Institute of Landscape Plants and Flowers, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Wenlue Li
- Zhejiang Xiaoshan Institute of Cotton and Bast Fiber Crops, Zhejiang Institute of Landscape Plants and Flowers, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Lina Zou
- Zhejiang Xiaoshan Institute of Cotton and Bast Fiber Crops, Zhejiang Institute of Landscape Plants and Flowers, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Chendong Sun
- The Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
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3
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The intricate roles of RCC1 in normal cells and cancer cells. Biochem Soc Trans 2022; 50:83-93. [PMID: 35191966 DOI: 10.1042/bst20210861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/24/2022] [Accepted: 02/02/2022] [Indexed: 11/17/2022]
Abstract
RCC1 (regulator of chromosome condensation 1) is a highly conserved chromatin-binding protein and the only known guanine-nucleotide exchange factor of Ran (a nuclear Ras homolog). RCC1 plays an essential role in the regulation of cell cycle-related activities such as nuclear envelope formation, nuclear pore complex and spindle assembly, and nucleocytoplasmic transport. Over the last decade, increasing evidence has emerged highlighting the potential relevance of RCC1 to carcinogenesis, especially cervical, lung, and breast cancer. In this review, we briefly discuss the roles of RCC1 in both normal and tumor cells based on articles published in recent years, followed by a brief overview of future perspectives in the field.
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4
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Phosphorylation of RCC1 on Serine 11 Facilitates G1/S Transition in HPV E7-Expressing Cells. Biomolecules 2021; 11:biom11070995. [PMID: 34356619 PMCID: PMC8301946 DOI: 10.3390/biom11070995] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/01/2021] [Accepted: 07/01/2021] [Indexed: 11/25/2022] Open
Abstract
Persistent infection of high-risk human papillomavirus (HR-HPV) plays a causal role in cervical cancer. Regulator of chromosome condensation 1 (RCC1) is a critical cell cycle regulator, which undergoes a few post-translational modifications including phosphorylation. Here, we showed that serine 11 (S11) of RCC1 was phosphorylated in HPV E7-expressing cells. However, S11 phosphorylation was not up-regulated by CDK1 in E7-expressing cells; instead, the PI3K/AKT/mTOR pathway promoted S11 phosphorylation. Knockdown of AKT or inhibition of the PI3K/AKT/mTOR pathway down-regulated phosphorylation of RCC1 S11. Furthermore, S11 phosphorylation occurred throughout the cell cycle, and reached its peak during the mitosis phase. Our previous data proved that RCC1 was necessary for the G1/S cell cycle progression, and in the present study we showed that the RCC1 mutant, in which S11 was mutated to alanine (S11A) to mimic non-phosphorylation status, lost the ability to facilitate G1/S transition in E7-expressing cells. Moreover, RCC1 S11 was phosphorylated by the PI3K/AKT/mTOR pathway in HPV-positive cervical cancer SiHa and HeLa cells. We conclude that S11 of RCC1 is phosphorylated by the PI3K/AKT/mTOR pathway and phosphorylation of RCC1 S11 facilitates the abrogation of G1 checkpoint in HPV E7-expressing cells. In short, our study explores a new role of RCC1 S11 phosphorylation in cell cycle regulation.
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5
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Clarke PR. Keep it focused: PRMT6 drives the localization of RCC1 to chromosomes to facilitate mitosis, cell proliferation, and tumorigenesis. Mol Cell 2021; 81:1128-1129. [PMID: 33740472 DOI: 10.1016/j.molcel.2021.02.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Huang et al. (2021) identified a mechanism acting through the arginine methyltransferase PRMT6 that stabilizes the interaction of RCC1 with chromatin, promoting cell proliferation and tumorigenicity. Targeting this mechanism might enhance the treatment of tumors such as glioblastoma.
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Affiliation(s)
- Paul R Clarke
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4102, Australia.
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6
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Huang T, Yang Y, Song X, Wan X, Wu B, Sastry N, Horbinski CM, Zeng C, Tiek D, Goenka A, Liu F, Brennan CW, Kessler JA, Stupp R, Nakano I, Sulman EP, Nishikawa R, James CD, Zhang W, Xu W, Hu B, Cheng SY. PRMT6 methylation of RCC1 regulates mitosis, tumorigenicity, and radiation response of glioblastoma stem cells. Mol Cell 2021; 81:1276-1291.e9. [PMID: 33539787 DOI: 10.1016/j.molcel.2021.01.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 11/02/2020] [Accepted: 01/11/2021] [Indexed: 12/22/2022]
Abstract
Aberrant cell proliferation is a hallmark of cancer, including glioblastoma (GBM). Here we report that protein arginine methyltransferase (PRMT) 6 activity is required for the proliferation, stem-like properties, and tumorigenicity of glioblastoma stem cells (GSCs), a subpopulation in GBM critical for malignancy. We identified a casein kinase 2 (CK2)-PRMT6-regulator of chromatin condensation 1 (RCC1) signaling axis whose activity is an important contributor to the stem-like properties and tumor biology of GSCs. CK2 phosphorylates and stabilizes PRMT6 through deubiquitylation, which promotes PRMT6 methylation of RCC1, which in turn is required for RCC1 association with chromatin and activation of RAN. Disruption of this pathway results in defects in mitosis. EPZ020411, a specific small-molecule inhibitor for PRMT6, suppresses RCC1 arginine methylation and improves the cytotoxic activity of radiotherapy against GSC brain tumor xenografts. This study identifies a CK2α-PRMT6-RCC1 signaling axis that can be therapeutically targeted in the treatment of GBM.
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Affiliation(s)
- Tianzhi Huang
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Yongyong Yang
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Xiao Song
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Xuechao Wan
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Bingli Wu
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Namratha Sastry
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Craig M Horbinski
- Department of Pathology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Department of Neurological Surgery, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Chang Zeng
- Department of Preventive Medicine, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Deanna Tiek
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Anshika Goenka
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Fabao Liu
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Cameron W Brennan
- Human Oncology and Pathogenesis Program, Department of Neurosurgery, Brain Tumor Center, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - John A Kessler
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Roger Stupp
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Department of Neurological Surgery, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Ichiro Nakano
- Department of Neurosurgery, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Erik P Sulman
- Department of Radiation Oncology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Ryo Nishikawa
- Department of Neuro-Oncology/Neurosurgery, Saitama Medical University International Medical Center, Saitama 350-1298, Japan
| | - Charles David James
- Department of Neurological Surgery, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Wei Zhang
- Department of Preventive Medicine, The Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Wei Xu
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Bo Hu
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
| | - Shi-Yuan Cheng
- The Ken & Ruth Davee Department of Neurology, The Lou and Jean Malnati Brain Tumor Institute, The Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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7
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Ren X, Jiang K, Zhang F. The Multifaceted Roles of RCC1 in Tumorigenesis. Front Mol Biosci 2020; 7:225. [PMID: 33102517 PMCID: PMC7522611 DOI: 10.3389/fmolb.2020.00225] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/11/2020] [Indexed: 01/31/2023] Open
Abstract
RCC1 (regulator of chromosome condensation 1) is the only known guanine nucleotide exchange factor of Ran, a nuclear Ras-like G protein. RCC1 combines with chromatin and Ran to establish a concentration gradient of RanGTP, thereby participating in a series of cell physiological activities. In this review, we discuss the structure of RCC1 and describe how RCC1 affects the formation and function of the nuclear envelope, spindle formation, and nuclear transport. We mainly focus on the effect of RCC1 on the cell cycle during tumorigenesis and the recent research progress that has been made in relation to different tumor types.
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Affiliation(s)
- Xuanqi Ren
- College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Kai Jiang
- College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Feng Zhang
- College of Life Sciences, Shanghai Normal University, Shanghai, China
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8
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Yau KC, Arnaoutov A, Aksenova V, Kaufhold R, Chen S, Dasso M. RanBP1 controls the Ran pathway in mammalian cells through regulation of mitotic RCC1 dynamics. Cell Cycle 2020; 19:1899-1916. [PMID: 32594833 PMCID: PMC7469662 DOI: 10.1080/15384101.2020.1782036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Ran GTPase plays critical roles in multiple cellular processes including interphase nucleocytoplasmic transport and mitotic spindle assembly. During mitosis in mammalian cells, GTP-bound Ran (Ran-GTP) is concentrated near mitotic chromatin while GDP-bound Ran (Ran-GDP) is more abundant distal to chromosomes. This pattern spatially controls spindle formation because Ran-GTP locally releases spindle assembly factors (SAFs), such as Hepatoma Up-Regulated Protein (HURP), from inhibitory interactions near chromosomes. Regulator of Chromatin Condensation 1 (RCC1) is Ran’s chromatin-bound exchange factor, and RanBP1 is a conserved Ran-GTP-binding protein that has been implicated as a mitotic regulator of RCC1 in embryonic systems. Here, we show that RanBP1 controls mitotic RCC1 dynamics in human somatic tissue culture cells. In addition, we observed the re-localization of HURP in metaphase cells after RanBP1 degradation, consistent with the idea that altered RCC1 dynamics functionally modulate SAF activities. Together, our findings reveal an important mitotic role for RanBP1 in human somatic cells, controlling the spatial distribution and magnitude of mitotic Ran-GTP production and thereby ensuring the accurate execution of Ran-dependent mitotic events. Abbreviations AID: Auxin-induced degron; FLIP: Fluorescence loss in photobleaching; FRAP: Fluorescence recovery after photobleaching; GDP: guanosine diphosphate; GTP: guanosine triphosphate; HURP: Hepatoma Up-Regulated Protein; NE: nuclear envelope; NEBD: Nuclear Envelope Breakdown; RanBP1: Ran-binding protein 1; RanGAP1: Ran GTPase-Activating Protein 1; RCC1: Regulator of Chromatin Condensation 1; RRR complex: RCC1/Ran/RanBP1 heterotrimeric complex; SAF: Spindle Assembly Factor; TIR1: Transport Inhibitor Response 1 protein; XEE: Xenopus egg extract.
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Affiliation(s)
- Ka Chun Yau
- Division of Molecular and Cellular Biology, National Institute for Child Health and Human Development, National Institutes of Health , Bethesda, MD 20892, USA
| | - Alexei Arnaoutov
- Division of Molecular and Cellular Biology, National Institute for Child Health and Human Development, National Institutes of Health , Bethesda, MD 20892, USA
| | - Vasilisa Aksenova
- Division of Molecular and Cellular Biology, National Institute for Child Health and Human Development, National Institutes of Health , Bethesda, MD 20892, USA
| | - Ross Kaufhold
- Division of Molecular and Cellular Biology, National Institute for Child Health and Human Development, National Institutes of Health , Bethesda, MD 20892, USA
| | - Shane Chen
- Division of Molecular and Cellular Biology, National Institute for Child Health and Human Development, National Institutes of Health , Bethesda, MD 20892, USA
| | - Mary Dasso
- Division of Molecular and Cellular Biology, National Institute for Child Health and Human Development, National Institutes of Health , Bethesda, MD 20892, USA
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9
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Beaudet D, Pham N, Skaik N, Piekny A. Importin binding mediates the intramolecular regulation of anillin during cytokinesis. Mol Biol Cell 2020; 31:1124-1139. [PMID: 32238082 PMCID: PMC7353161 DOI: 10.1091/mbc.e20-01-0006] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cytokinesis occurs by the ingression of an actomyosin ring that cleaves a cell into two daughters. This process is tightly controlled to avoid aneuploidy, and we previously showed that active Ran coordinates ring positioning with chromatin. Active Ran is high around chromatin, and forms an inverse gradient to cargo-bound importins. We found that the ring component anillin contains a nuclear localization signal (NLS) that binds to importin and is required for its function during cytokinesis. Here we reveal the mechanism whereby importin binding favors a conformation required for anillin's recruitment to the equatorial cortex. Active RhoA binds to the RhoA-binding domain causing an increase in accessibility of the nearby C2 domain containing the NLS. Importin binding subsequently stabilizes a conformation that favors interactions for cortical recruitment. In addition to revealing a novel mechanism for the importin-mediated regulation of a cortical protein, we also show how importin binding positively regulates protein function.
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Affiliation(s)
- Daniel Beaudet
- Department of Bioengineering, McGill University, Montreal, QC, Canada, H3A 0G4
| | - Nhat Pham
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
| | - Noha Skaik
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6
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10
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Guo L, Mohd KS, Ren H, Xin G, Jiang Q, Clarke PR, Zhang C. Phosphorylation of importin-α1 by CDK1-cyclin B1 controls mitotic spindle assembly. J Cell Sci 2019; 132:jcs232314. [PMID: 31434716 PMCID: PMC6765185 DOI: 10.1242/jcs.232314] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 08/09/2019] [Indexed: 12/22/2022] Open
Abstract
Importin-α serves as an adaptor linking importin-β to proteins carrying a nuclear localization sequence (NLS). During interphase, this interaction enables nuclear protein import, while in mitosis it regulates spindle assembly factors (SAFs) and controls microtubule nucleation, stabilization and spindle function. Here, we show that human importin-α1 is regulated during the cell cycle and is phosphorylated at two sites (threonine 9 and serine 62) during mitosis by the major mitotic protein kinase CDK1-cyclin B. Mutational analysis indicates that the mitotic phosphorylation of importin-α1 inhibits its binding to importin-β and promotes the release of TPX2 and KIFC1, which are then targeted like importin-β to the spindle. Loss of importin-α1 or expression of a non-phosphorylated mutant of importin-α1 results in the formation of shortened spindles with reduced microtubule density and induces a prolonged metaphase, whereas phosphorylation-mimicking mutants are functional in mitosis. We propose that phosphorylation of importin-α1 is a general mechanism for the spatial and temporal control of mitotic spindle assembly by CDK1-cyclin B1 that acts through the release of SAFs such as TPX2 and KIFC1 from inhibitory complexes that restrict spindle assembly.
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Affiliation(s)
- Li Guo
- The MOE Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing 100871, China
| | - Khamsah Suryati Mohd
- School of Medicine, Jacqui Wood Cancer Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - He Ren
- The MOE Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing 100871, China
| | - Guangwei Xin
- The MOE Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing 100871, China
| | - Qing Jiang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing 100871, China
| | - Paul R Clarke
- School of Medicine, Jacqui Wood Cancer Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
- The University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, Brisbane, QLD 4102, Australia
| | - Chuanmao Zhang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing 100871, China
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11
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Raccaud M, Friman ET, Alber AB, Agarwal H, Deluz C, Kuhn T, Gebhardt JCM, Suter DM. Mitotic chromosome binding predicts transcription factor properties in interphase. Nat Commun 2019; 10:487. [PMID: 30700703 PMCID: PMC6353955 DOI: 10.1038/s41467-019-08417-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/08/2019] [Indexed: 12/31/2022] Open
Abstract
Mammalian transcription factors (TFs) differ broadly in their nuclear mobility and sequence-specific/non-specific DNA binding. How these properties affect their ability to occupy specific genomic sites and modify the epigenetic landscape is unclear. The association of TFs with mitotic chromosomes observed by fluorescence microscopy is largely mediated by non-specific DNA interactions and differs broadly between TFs. Here we combine quantitative measurements of mitotic chromosome binding (MCB) of 501 TFs, TF mobility measurements by fluorescence recovery after photobleaching, single molecule imaging of DNA binding, and mapping of TF binding and chromatin accessibility. TFs associating to mitotic chromosomes are enriched in DNA-rich compartments in interphase and display slower mobility in interphase and mitosis. Remarkably, MCB correlates with relative TF on-rates and genome-wide specific site occupancy, but not with TF residence times. This suggests that non-specific DNA binding properties of TFs regulate their search efficiency and occupancy of specific genomic sites.
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Affiliation(s)
- Mahé Raccaud
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Elias T Friman
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Andrea B Alber
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Harsha Agarwal
- Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Cédric Deluz
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Timo Kuhn
- Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - J Christof M Gebhardt
- Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - David M Suter
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
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12
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Panzica MT, McNally FJ. Mechanisms that prevent catastrophic interactions between paternal chromosomes and the oocyte meiotic spindle. Cell Cycle 2018; 17:529-534. [PMID: 29375006 DOI: 10.1080/15384101.2018.1431495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Meiosis produces haploid gametes by accurately reducing chromosome ploidy through one round of DNA replication and two subsequent rounds of chromosome segregation and cell division. The cell divisions of female meiosis are highly asymmetric and give rise to a large egg and two very small polar bodies that do not contribute to development. These asymmetric divisions are driven by meiotic spindles that are small relative to the size of the egg and have one pole juxtaposed against the cell cortex to promote polar body extrusion. An additional unique feature of female meiosis is that fertilization occurs before extrusion of the second polar body in nearly all animal species. Thus sperm-derived chromosomes are present in the egg during female meiosis. Here, we explore the idea that the asymmetry of female meiosis spatially separates the sperm from the meiotic spindle to prevent detrimental interactions between the spindle and the paternal chromosomes.
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Affiliation(s)
- Michelle T Panzica
- a Department of Molecular and Cellular Biology , University of California , Davis , Davis , CA , USA
| | - Francis J McNally
- a Department of Molecular and Cellular Biology , University of California , Davis , Davis , CA , USA
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13
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Sankhala RS, Lokareddy RK, Begum S, Pumroy RA, Gillilan RE, Cingolani G. Three-dimensional context rather than NLS amino acid sequence determines importin α subtype specificity for RCC1. Nat Commun 2017; 8:979. [PMID: 29042532 PMCID: PMC5645467 DOI: 10.1038/s41467-017-01057-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 08/15/2017] [Indexed: 12/27/2022] Open
Abstract
Active nuclear import of Ran exchange factor RCC1 is mediated by importin α3. This pathway is essential to generate a gradient of RanGTP on chromatin that directs nucleocytoplasmic transport, mitotic spindle assembly and nuclear envelope formation. Here we identify the mechanisms of importin α3 selectivity for RCC1. We find this isoform binds RCC1 with one order of magnitude higher affinity than the generic importin α1, although the two isoforms share an identical NLS-binding groove. Importin α3 uses its greater conformational flexibility to wedge the RCC1 β-propeller flanking the NLS against its lateral surface, preventing steric clashes with its Armadillo-core. Removing the β-propeller, or inserting a linker between NLS and β-propeller, disrupts specificity for importin α3, demonstrating the structural context rather than NLS sequence determines selectivity for isoform 3. We propose importin α3 evolved to recognize topologically complex NLSs that lie next to bulky domains or are masked by quaternary structures.Importin α3 facilitates the nuclear transport of the Ran guanine nucleotide exchange factor RCC1. Here the authors reveal the molecular basis for the selectivity of RCC1 for importin α3 vs the generic importin α1 and discuss the evolution of importin α isoforms.
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Affiliation(s)
- Rajeshwer S Sankhala
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA, 19107, USA
| | - Ravi K Lokareddy
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA, 19107, USA
| | - Salma Begum
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA, 19107, USA
| | - Ruth A Pumroy
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA, 19107, USA.,Department of Biochemistry, University of Utah, 15N Medical Drive East, Salt Lake City, UT, 84112-5650, USA
| | - Richard E Gillilan
- Macromolecular Diffraction Facility, Cornell High Energy Synchrotron Source (MacCHESS), Cornell University, 161 Synchrotron Drive, Ithaca, NY, 14853, USA
| | - Gino Cingolani
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA, 19107, USA. .,Institute of Biomembranes and Bioenergetics, National Research Council, Via Amendola 165/A, Bari, 70126, Italy.
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14
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Beaudet D, Akhshi T, Phillipp J, Law C, Piekny A. Active Ran regulates anillin function during cytokinesis. Mol Biol Cell 2017; 28:3517-3531. [PMID: 28931593 PMCID: PMC5683762 DOI: 10.1091/mbc.e17-04-0253] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 09/06/2017] [Accepted: 09/13/2017] [Indexed: 11/11/2022] Open
Abstract
We describe a novel mechanism by which active Ran regulates anillin during cytokinesis. Anillin is highly conserved and coordinates RhoA, actomyosin, microtubules, and the membrane for cytokinesis in mammalian cells. This study implicates Ran-GTP in influencing cortical contractility during anaphase by regulating anillin function. Cytokinesis cleaves a cell into two daughters at the end of mitosis, and must be spatially coordinated with chromosome segregation to prevent aneuploidy. The dogma is that the mitotic spindle governs the assembly and constriction of an actomyosin ring. Here, we reveal a function for active Ran in spatially restricting the ring. Our model is that during anaphase, “free” importins, whose gradient inversely correlates with active Ran and chromatin position, function as a molecular ruler for the recruitment and localization of anillin, a contractile protein and a crucial regulator of cytokinesis. We found that decreasing Ran-GTP levels or tethering active Ran to the equatorial membrane affects anillin’s localization and causes cytokinesis phenotypes. Anillin contains a conserved nuclear localization signal (NLS) at its C-terminus that binds to importin-β and is required for cortical polarity and cytokinesis. Mutating the NLS decreases anillin’s cortical affinity, causing it to be more dominantly regulated by microtubules. Anillin contains a RhoA-GTP binding domain, which autoinhibits the NLS and the neighboring microtubule-binding domain, and RhoA-GTP binding may relieve this inhibition during mitosis. Retention of the C-terminal NLS in anillin homologues suggests that this is a conserved mechanism for controlling anillin function.
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Affiliation(s)
- Daniel Beaudet
- Department of Biology, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Tara Akhshi
- Program in Cell Biology, the Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Julia Phillipp
- Department of Biology, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Christopher Law
- Centre for Microscopy and Cellular Imaging, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Alisa Piekny
- Program in Cell Biology, the Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
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15
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Raccaud M, Suter DM. Transcription factor retention on mitotic chromosomes: regulatory mechanisms and impact on cell fate decisions. FEBS Lett 2017; 592:878-887. [PMID: 28862742 DOI: 10.1002/1873-3468.12828] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/14/2017] [Accepted: 08/24/2017] [Indexed: 12/21/2022]
Abstract
During mitosis, gene transcription stops, and the bulk of DNA-binding proteins are excluded from condensed chromosomes. While most gene-specific transcription factors are largely evicted from mitotic chromosomes, a subset remains bound to specific and non-specific DNA sites. Here, we review the current knowledge on the mechanisms leading to the retention of a subset of transcription factors on mitotic chromosomes and discuss the implications in gene expression regulation and their potential as an epigenetic mechanism controlling stem cell self-renewal and differentiation.
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Affiliation(s)
- Mahé Raccaud
- UPSUTER, Institute of Bioengineering (IBI), School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - David M Suter
- UPSUTER, Institute of Bioengineering (IBI), School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
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16
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Deschamps T, Bazot Q, Leske DM, MacLeod R, Mompelat D, Tafforeau L, Lotteau V, Maréchal V, Baillie GS, Gruffat H, Wilson JB, Manet E. Epstein-Barr virus nuclear antigen 1 interacts with regulator of chromosome condensation 1 dynamically throughout the cell cycle. J Gen Virol 2017; 98:251-265. [PMID: 28284242 DOI: 10.1099/jgv.0.000681] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is a sequence-specific DNA-binding protein that plays an essential role in viral episome replication and segregation, by recruiting the cellular complex of DNA replication onto the origin (oriP) and by tethering the viral DNA onto the mitotic chromosomes. Whereas the mechanisms of viral DNA replication are well documented, those involved in tethering EBNA1 to the cellular chromatin are far from being understood. Here, we have identified regulator of chromosome condensation 1 (RCC1) as a novel cellular partner for EBNA1. RCC1 is the major nuclear guanine nucleotide exchange factor for the small GTPase Ran enzyme. RCC1, associated with chromatin, is involved in the formation of RanGTP gradients critical for nucleo-cytoplasmic transport, mitotic spindle formation and nuclear envelope reassembly following mitosis. Using several approaches, we have demonstrated a direct interaction between these two proteins and found that the EBNA1 domains responsible for EBNA1 tethering to the mitotic chromosomes are also involved in the interaction with RCC1. The use of an EBNA1 peptide array confirmed the interaction of RCC1 with these regions and also the importance of the N-terminal region of RCC1 in this interaction. Finally, using confocal microscopy and Förster resonance energy transfer analysis to follow the dynamics of interaction between the two proteins throughout the cell cycle, we have demonstrated that EBNA1 and RCC1 closely associate on the chromosomes during metaphase, suggesting an essential role for the interaction during this phase, perhaps in tethering EBNA1 to mitotic chromosomes.
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Affiliation(s)
- Thibaut Deschamps
- Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon 69364, France.,CNRS, UMR5308, Lyon 69364, France.,CIRI, International Center for Infectiology Research, Oncogenic Herpesviruses Team, Université de Lyon, Lyon 69364, France.,Ecole Normale Supérieure de Lyon, Lyon 69364, France.,INSERM, U1111, Lyon 69364, France
| | - Quentin Bazot
- Ecole Normale Supérieure de Lyon, Lyon 69364, France.,CNRS, UMR5308, Lyon 69364, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon 69364, France.,Present address: Section of Virology, Department of Medicine, Imperial College London, St Mary's Campus, London, UK.,CIRI, International Center for Infectiology Research, Oncogenic Herpesviruses Team, Université de Lyon, Lyon 69364, France.,INSERM, U1111, Lyon 69364, France
| | - Derek M Leske
- Present address: University of Oxford, Ludwig Institute for Cancer Research, Oxford, UK.,College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Ruth MacLeod
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Dimitri Mompelat
- Present address: University Joseph Fourier, Pathogenesis and Lentiviral Vaccination Laboratory, Grenoble, France.,INSERM, U1111, Lyon 69364, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon 69364, France.,Ecole Normale Supérieure de Lyon, Lyon 69364, France.,CIRI, International Center for Infectiology Research, Oncogenic Herpesviruses Team, Université de Lyon, Lyon 69364, France.,CNRS, UMR5308, Lyon 69364, France
| | - Lionel Tafforeau
- CIRI, International Center for Infectiology Research, Cell Biology of Viral Infections Team, Université de Lyon, Lyon 69364, France.,INSERM, U1111, Lyon 69364, France.,Present address: Cell Biology Lab, University of Mons, Mons, Belgium.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon 69364, France
| | - Vincent Lotteau
- Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon 69364, France.,Ecole Normale Supérieure de Lyon, Lyon 69364, France.,CNRS, UMR5308, Lyon 69364, France.,INSERM, U1111, Lyon 69364, France.,CIRI, International Center for Infectiology Research, Cell Biology of Viral Infections Team, Université de Lyon, Lyon 69364, France
| | - Vincent Maréchal
- UPMC Université Paris 6, Inserm, Centre d'Immunologie et des Maladies Infectieuses (Cimi-Paris), UMR 1135, ERL CNRS 8255, F-75013 Paris, France
| | - George S Baillie
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Henri Gruffat
- CNRS, UMR5308, Lyon 69364, France.,INSERM, U1111, Lyon 69364, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon 69364, France.,CIRI, International Center for Infectiology Research, Oncogenic Herpesviruses Team, Université de Lyon, Lyon 69364, France.,Ecole Normale Supérieure de Lyon, Lyon 69364, France
| | - Joanna B Wilson
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Evelyne Manet
- INSERM, U1111, Lyon 69364, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon 69364, France.,CIRI, International Center for Infectiology Research, Oncogenic Herpesviruses Team, Université de Lyon, Lyon 69364, France.,Ecole Normale Supérieure de Lyon, Lyon 69364, France.,CNRS, UMR5308, Lyon 69364, France
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17
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Zheng H, Wu H, Pan X, Jin W, Li X. Aberrant Meiotic Modulation Partially Contributes to the Lower Germination Rate of Pollen Grains in Maize (Zea mays L.) Under Low Nitrogen Supply. PLANT & CELL PHYSIOLOGY 2017; 58:342-353. [PMID: 28007967 DOI: 10.1093/pcp/pcw195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 11/08/2016] [Indexed: 06/06/2023]
Abstract
Pollen germination is an essential step towards successful pollination during maize reproduction. How low niutrogen (N) affects pollen germination remains an interesting biological question to be addressed. We found that only low N resulted in a significantly lower germination rate of pollen grains after 4 weeks of low N, phosphorus or potassium treatment in maize production. Importantly, cytological analysis showed 7-fold more micronuclei in male meiocytes under the low N treatment than in the control, indicating that the lower germination rate of pollen grains was partially due to numerous chromosome loss events resulting from preceding meiosis. The appearance of 10 bivalents in the control and low N cells at diakinesis suggested that chromosome pairing and recombination in meiosis I was not affected by low N. Further gene expression analysis revealed dramatic down-regulation of Nuclear Division Cycle 80 (Ndc80) and Regulator of Chromosome Condensation 1 (Rcc1-1) expression and up-regulation of Cell Division Cycle 20 (Cdc20-1) expression, although no significant difference in the expression level of kinetochore foundation proteins Centromeric Histone H3 (Cenh3) and Centromere Protein C (Cenpc) and cohesion regulators Recombination 8 (Rec8) and Shugoshin (Sgo1) was observed. Aberrant modulation of three key meiotic regulators presumably resulted in a high likelihood of erroneous chromosome segregation, as testified by pronounced lagging chromosomes at anaphase I or cell cycle disruption at meiosis II. Thus, we proposed a cytogenetic mechanism whereby low N affects male meiosis and causes a higher chromosome loss frequency and eventually a lower germination rate of pollen grains in a staple crop plant.
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Affiliation(s)
- Hongyan Zheng
- Key Laboratory of Plant-Soil Interactions of the Ministry of Education, and Department of Plant Nutrition, China Agricultural University, Beijing, China
| | - Huamao Wu
- Key Laboratory of Plant-Soil Interactions of the Ministry of Education, and Department of Plant Nutrition, China Agricultural University, Beijing, China
| | - Xiaoying Pan
- Key Laboratory of Plant-Soil Interactions of the Ministry of Education, and Department of Plant Nutrition, China Agricultural University, Beijing, China
| | - Weiwei Jin
- The National Maize Center, and Department of Plant Genetics and Breeding, China Agricultural University, Beijing, China
| | - Xuexian Li
- Key Laboratory of Plant-Soil Interactions of the Ministry of Education, and Department of Plant Nutrition, China Agricultural University, Beijing, China
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18
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Garrido G, Vernos I. Non-centrosomal TPX2-Dependent Regulation of the Aurora A Kinase: Functional Implications for Healthy and Pathological Cell Division. Front Oncol 2016; 6:88. [PMID: 27148480 PMCID: PMC4831974 DOI: 10.3389/fonc.2016.00088] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/29/2016] [Indexed: 01/09/2023] Open
Abstract
Aurora A has been extensively characterized as a centrosomal kinase with essential functions during cell division including centrosome maturation and separation and spindle assembly. However, Aurora A localization is not restricted to the centrosomes and compelling evidence support the existence of specific mechanisms of activation and functions for non-centrosomal Aurora A in the dividing cell. It has been now well established that spindle assembly involves an acentrosomal RanGTP-dependent pathway that triggers microtubule assembly and organization in the proximity of the chromosomes whether centrosomes are present or not. The mechanism involves the regulation of a number of NLS-containing proteins, generically called SAFS (Spindle Assembly Factors) that exert their functions upon release from karyopherins by RanGTP. One of them, the nuclear protein TPX2 interacts with and activates Aurora A upon release from importins by RanGTP. This basic mechanism triggers the activation of Aurora A in the proximity of the chromosomes potentially translating the RanGTP signaling gradient centered on the chromosome into an Aurora A phosphorylation network. Here, we will review our current knowledge on the RanGTP-dependent TPX2 activation of Aurora A away from centrosomes: from the mechanism of activation and its functional consequences on the kinase stability and regulation to its roles in spindle assembly and cell division. We will then focus on the substrates of the TPX2-activated Aurora A having a role in microtubule nucleation, stabilization, and organization. Finally, we will briefly discuss the implications of the use of Aurora A inhibitors in anti-tumor therapies in the light of its functional interaction with TPX2.
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Affiliation(s)
- Georgina Garrido
- Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Isabelle Vernos
- Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; Institució Catalana de Recerca I Estudis Avançats (ICREA), Barcelona, Spain
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19
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Stelma T, Chi A, van der Watt PJ, Verrico A, Lavia P, Leaner VD. Targeting nuclear transporters in cancer: Diagnostic, prognostic and therapeutic potential. IUBMB Life 2016; 68:268-80. [PMID: 26970212 DOI: 10.1002/iub.1484] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 01/20/2016] [Indexed: 01/10/2023]
Abstract
The Karyopherin superfamily is a major class of soluble transport receptors consisting of both import and export proteins. The trafficking of proteins involved in transcription, cell signalling and cell cycle regulation among other functions across the nuclear membrane is essential for normal cellular functioning. However, in cancer cells, the altered expression or localization of nuclear transporters as well as the disruption of endogenous nuclear transport inhibitors are some ways in which the Karyopherin proteins are dysregulated. The value of nuclear transporters in the diagnosis, prognosis and treatment of cancer is currently being elucidated with recent studies highlighting their potential as biomarkers and therapeutic targets.
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Affiliation(s)
- Tamara Stelma
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, SAMRC/UCT Gynaecological Cancer Research Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Alicia Chi
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, SAMRC/UCT Gynaecological Cancer Research Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Pauline J van der Watt
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, SAMRC/UCT Gynaecological Cancer Research Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Annalisa Verrico
- Institute of Molecular Biology and Pathology, National Research Council of Italy, C/O University of Roma "La Sapienza", Rome, Italy
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology, National Research Council of Italy, C/O University of Roma "La Sapienza", Rome, Italy
| | - Virna D Leaner
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, SAMRC/UCT Gynaecological Cancer Research Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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20
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Binkert M, Crocco CD, Ekundayo B, Lau K, Raffelberg S, Tilbrook K, Yin R, Chappuis R, Schalch T, Ulm R. Revisiting chromatin binding of the Arabidopsis UV-B photoreceptor UVR8. BMC PLANT BIOLOGY 2016; 16:42. [PMID: 26864020 PMCID: PMC4750278 DOI: 10.1186/s12870-016-0732-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/06/2016] [Indexed: 05/05/2023]
Abstract
BACKGROUND Plants perceive UV-B through the UV RESISTANCE LOCUS 8 (UVR8) photoreceptor and UVR8 activation leads to changes in gene expression such as those associated with UV-B acclimation and stress tolerance. Albeit functionally unrelated, UVR8 shows some homology with RCC1 (Regulator of Chromatin Condensation 1) proteins from non-plant organisms at the sequence level. These proteins act as guanine nucleotide exchange factors for Ran GTPases and bind chromatin via histones. Subsequent to the revelation of this sequence homology, evidence was presented showing that UVR8 activity involves interaction with chromatin at the loci of some target genes through histone binding. This suggested a UVR8 mode-of-action intimately and directly linked with gene transcription. However, several aspects of UVR8 chromatin association remained undefined, namely the impact of UV-B on the process and how UVR8 chromatin association related to the transcription factor ELONGATED HYPOCOTYL 5 (HY5), which is important for UV-B signalling and has overlapping chromatin targets. Therefore, we have investigated UVR8 chromatin association in further detail. RESULTS Unlike the claims of previous studies, our chromatin immunoprecipitation (ChIP) experiments do not confirm UVR8 chromatin association. In contrast to human RCC1, recombinant UVR8 also does not bind nucleosomes in vitro. Moreover, fusion of a VP16 activation domain to UVR8 did not alter expression of proposed UVR8 target genes in transient gene expression assays. Finally, comparison of the Drosophila DmRCC1 and the Arabidopsis UVR8 crystal structures revealed that critical histone- and DNA-interaction residues apparent in DmRCC1 are not conserved in UVR8. CONCLUSION This has led us to conclude that the cellular activity of UVR8 likely does not involve its specific binding to chromatin at target genes.
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Affiliation(s)
- Melanie Binkert
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Carlos D Crocco
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Babatunde Ekundayo
- Department of Molecular Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Kelvin Lau
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Sarah Raffelberg
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Kimberley Tilbrook
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
- Present Address: CSIRO Agriculture, Canberra, Australia.
| | - Ruohe Yin
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Richard Chappuis
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Thomas Schalch
- Department of Molecular Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211, Geneva 4, Switzerland.
| | - Roman Ulm
- Department of Botany and Plant Biology, University of Geneva, Sciences III, 30 Quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211, Geneva 4, Switzerland.
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21
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Chen JWC, Barker AR, Wakefield JG. The Ran Pathway in Drosophila melanogaster Mitosis. Front Cell Dev Biol 2015; 3:74. [PMID: 26636083 PMCID: PMC4659922 DOI: 10.3389/fcell.2015.00074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/09/2015] [Indexed: 11/29/2022] Open
Abstract
Over the last two decades, the small GTPase Ran has emerged as a central regulator of both mitosis and meiosis, particularly in the generation, maintenance, and regulation of the microtubule (MT)-based bipolar spindle. Ran-regulated pathways in mitosis bear many similarities to the well-characterized functions of Ran in nuclear transport and, as with transport, the majority of these mitotic effects are mediated through affecting the physical interaction between karyopherins and Spindle Assembly Factors (SAFs)—a loose term describing proteins or protein complexes involved in spindle assembly through promoting nucleation, stabilization, and/or depolymerization of MTs, through anchoring MTs to specific structures such as centrosomes, chromatin or kinetochores, or through sliding MTs along each other to generate the force required to achieve bipolarity. As such, the Ran-mediated pathway represents a crucial functional module within the wider spindle assembly landscape. Research into mitosis using the model organism Drosophila melanogaster has contributed substantially to our understanding of centrosome and spindle function. However, in comparison to mammalian systems, very little is known about the contribution of Ran-mediated pathways in Drosophila mitosis. This article sets out to summarize our understanding of the roles of the Ran pathway components in Drosophila mitosis, focusing on the syncytial blastoderm embryo, arguing that it can provide important insights into the conserved functions on Ran during spindle formation.
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Affiliation(s)
- Jack W C Chen
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Amy R Barker
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK ; Centre for Microvascular Research, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London London, UK
| | - James G Wakefield
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
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22
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Jiang H, He X, Feng D, Zhu X, Zheng Y. RanGTP aids anaphase entry through Ubr5-mediated protein turnover. J Cell Biol 2015; 211:7-18. [PMID: 26438829 PMCID: PMC4602037 DOI: 10.1083/jcb.201503122] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 08/25/2015] [Indexed: 01/14/2023] Open
Abstract
Cells sense the overall chromosome congression state in metaphase to promote anaphase entry using RanGTP, which induces the reduction of two spindle assembly checkpoint proteins, BuGZ and Bub3, via the E3 ligase Ubr5. RanGTP is known to regulate the spindle assembly checkpoint (SAC), but the underlying molecular mechanism is unclear. BuGZ stabilizes SAC protein Bub3 through direct interaction and facilitates its mitotic function. Here we show that RanGTP promotes the turnover of BuGZ and Bub3 in metaphase, which in turn facilitates metaphase-to-anaphase transition. BuGZ and Bub3 interact with either importin-β or an E3 ubiquitin ligase, Ubr5. RanGTP promotes the dissociation of importin-β from BuGZ and Bub3 in metaphase. This results in increased binding of BuGZ and Bub3 to Ubr5, leading to ubiquitination and subsequent turnover of both proteins. We propose that elevated metaphase RanGTP levels use Ubr5 to couple overall chromosome congression to SAC silencing.
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Affiliation(s)
- Hao Jiang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218
| | - Xiaonan He
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Di Feng
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218
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23
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Abstract
Chromosomes are not only carriers of the genetic material, but also actively regulate the assembly of complex intracellular architectures. During mitosis, chromosome-induced microtubule polymerisation ensures spindle assembly in cells without centrosomes and plays a supportive role in centrosome-containing cells. Chromosomal signals also mediate post-mitotic nuclear envelope (NE) re-formation. Recent studies using novel approaches to manipulate histones in oocytes, where functions can be analysed in the absence of transcription, have established that nucleosomes, but not DNA alone, mediate the chromosomal regulation of spindle assembly and NE formation. Both processes require the generation of RanGTP by RCC1 recruited to nucleosomes but nucleosomes also acquire cell cycle stage specific regulators, Aurora B in mitosis and ELYS, the initiator of nuclear pore complex assembly, at mitotic exit. Here, we review the mechanisms by which nucleosomes control assembly and functions of the spindle and the NE, and discuss their implications for genome maintenance.
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Affiliation(s)
- Christian Zierhut
- Laboratory of Chromosome and Cell Biology, Rockefeller University, New York, NY, USA
| | - Hironori Funabiki
- Laboratory of Chromosome and Cell Biology, Rockefeller University, New York, NY, USA
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24
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Beaufay F, Coppine J, Mayard A, Laloux G, De Bolle X, Hallez R. A NAD-dependent glutamate dehydrogenase coordinates metabolism with cell division in Caulobacter crescentus. EMBO J 2015; 34:1786-800. [PMID: 25953831 DOI: 10.15252/embj.201490730] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 04/21/2015] [Indexed: 11/09/2022] Open
Abstract
Coupling cell cycle with nutrient availability is a crucial process for all living cells. But how bacteria control cell division according to metabolic supplies remains poorly understood. Here, we describe a molecular mechanism that coordinates central metabolism with cell division in the α-proteobacterium Caulobacter crescentus. This mechanism involves the NAD-dependent glutamate dehydrogenase GdhZ and the oxidoreductase-like KidO. While enzymatically active GdhZ directly interferes with FtsZ polymerization by stimulating its GTPase activity, KidO bound to NADH destabilizes lateral interactions between FtsZ protofilaments. Both GdhZ and KidO share the same regulatory network to concomitantly stimulate the rapid disassembly of the Z-ring, necessary for the subsequent release of progeny cells. Thus, this mechanism illustrates how proteins initially dedicated to metabolism coordinate cell cycle progression with nutrient availability.
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Affiliation(s)
- François Beaufay
- Bacterial Cell Cycle & Development (BCcD), URBM, University of Namur, Namur, Belgium
| | - Jérôme Coppine
- Bacterial Cell Cycle & Development (BCcD), URBM, University of Namur, Namur, Belgium
| | - Aurélie Mayard
- Bacterial Cell Cycle & Development (BCcD), URBM, University of Namur, Namur, Belgium
| | - Géraldine Laloux
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Xavier De Bolle
- Bacterial Cell Cycle & Development (BCcD), URBM, University of Namur, Namur, Belgium
| | - Régis Hallez
- Bacterial Cell Cycle & Development (BCcD), URBM, University of Namur, Namur, Belgium
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25
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Lowe AR, Tang JH, Yassif J, Graf M, Huang WYC, Groves JT, Weis K, Liphardt JT. Importin-β modulates the permeability of the nuclear pore complex in a Ran-dependent manner. eLife 2015; 4. [PMID: 25748139 PMCID: PMC4375889 DOI: 10.7554/elife.04052] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 02/27/2015] [Indexed: 11/13/2022] Open
Abstract
Soluble karyopherins of the importin-β (impβ) family use RanGTP to transport cargos directionally through the nuclear pore complex (NPC). Whether impβ or RanGTP regulate the permeability of the NPC itself has been unknown. In this study, we identify a stable pool of impβ at the NPC. A subpopulation of this pool is rapidly turned-over by RanGTP, likely at Nup153. Impβ, but not transportin-1 (TRN1), alters the pore's permeability in a Ran-dependent manner, suggesting that impβ is a functional component of the NPC. Upon reduction of Nup153 levels, inert cargos more readily equilibrate across the NPC yet active transport is impaired. When purified impβ or TRN1 are mixed with Nup153 in vitro, higher-order, multivalent complexes form. RanGTP dissolves the impβ•Nup153 complexes but not those of TRN1•Nup153. We propose that impβ and Nup153 interact at the NPC's nuclear face to form a Ran-regulated mesh that modulates NPC permeability. DOI:http://dx.doi.org/10.7554/eLife.04052.001 In our cells, genetic material is contained within the nucleus, which is separated from the rest of the cell by a double-layered membrane called the nuclear envelope. Within this membrane there are pores that allow proteins and other molecules to enter and exit the nucleus. Small molecules can pass through these pores unaided, which is known as ‘passive’ transport. However, larger cargos need help from transport receptor proteins in a process called ‘active’ transport. Large cargos bind to transport receptors, such as importin-β, in the cytoplasm and are then guided through the pore. Once the cargo and importin-β are inside the nucleus, a protein called RanGTP binds to importin-β to release the cargo. It is thought that importin-β and RanGTP are only important for the active transport of cargo. Here, Lowe et al. studied how importin-β interacts with the pore. The experiments show that in the absence of RanGTP, importin-β accumulates inside the pore and binds to a protein called Nup153, which is part of the complex of proteins that makes up the pore. However, when RanGTP is present, some of the importin-β is displaced from Nup153 and leaves the pore, which makes it easier for cargo to pass through. Further experiments show that when Nup153 and importin-β are mixed, they associate into a gel-like material that can be ‘melted’ by RanGTP. Lowe et al. propose a model for how RanGTP may control the flow of cargo through the nuclear pore by affecting the binding of importin-β to Nup153. Lowe et al.'s findings suggest that passive and active transport of cargo across the nuclear pore are fundamentally connected and suggest that RanGTP provides the cell with an additional layer of control over nucleocytoplasmic transport. DOI:http://dx.doi.org/10.7554/eLife.04052.002
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Affiliation(s)
- Alan R Lowe
- Institute for Structural and Molecular Biology, University College London and Birkbeck College, London, United Kingdom
| | - Jeffrey H Tang
- Department of Physics, University of California, Berkeley, Berkeley, United States
| | - Jaime Yassif
- Department of Physics, University of California, Berkeley, Berkeley, United States
| | - Michael Graf
- Section of Life Sciences and Technologies, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
| | - William Y C Huang
- Department of Chemistry, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Jay T Groves
- QB3, University of California, Berkeley, Berkeley, United States
| | - Karsten Weis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Jan T Liphardt
- Department of Physics, University of California, Berkeley, Berkeley, United States
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26
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Disruption of the ran system by cysteine oxidation of the nucleotide exchange factor RCC1. Mol Cell Biol 2014; 35:566-81. [PMID: 25452301 DOI: 10.1128/mcb.01133-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Transport regulation by the Ran GTPase requires its nuclear localization and GTP loading by the chromatin-associated exchange factor RCC1. These reactions generate Ran protein and Ran nucleotide gradients between the nucleus and the cytoplasm. Cellular stress disrupts the Ran gradients, but the specific mechanisms underlying this disruption have not been elucidated. We used biochemical approaches to determine how oxidative stress disrupts the Ran system. RCC1 exchange activity was reduced by diamide-induced oxidative stress and restored with dithiothreitol. Using mass spectrometry, we found that multiple solvent-exposed cysteines in RCC1 are oxidized in cells treated with diamide. The cysteines oxidized in RCC1 included Cys93, which is solvent exposed and unique because it becomes buried upon contact with Ran. A Cys93Ser substitution dramatically reduced exchange activity through an effect on RCC1 binding to RanGDP. Diamide treatment reduced the size of the mobile fraction of RCC1-green fluorescent protein in cells and inhibited nuclear import in digitonin-permeabilized cell assays. The Ran protein gradient was also disrupted by UV-induced stress but without affecting RCC1 exchange activity. Our data suggest that stress can disrupt the Ran gradients through RCC1-dependent and RCC1-independent mechanisms, possibly dependent on the particular stress condition.
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27
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Zhang MS, Arnaoutov A, Dasso M. RanBP1 governs spindle assembly by defining mitotic Ran-GTP production. Dev Cell 2014; 31:393-404. [PMID: 25458009 DOI: 10.1016/j.devcel.2014.10.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/10/2014] [Accepted: 10/22/2014] [Indexed: 01/06/2023]
Abstract
Accurate control of the Ras-related nuclear protein (Ran) GTPase cycle depends on the regulated activity of regulator of chromosome condensation 1 (RCC1), Ran's nucleotide exchange factor. RanBP1 has been characterized as a coactivator of the Ran GTPase-activating protein RanGAP1. RanBP1 can also form a stable complex with Ran and RCC1, although the dynamics and function of this complex remain poorly understood. Here, we show that formation of the heterotrimeric RCC1/Ran/RanBP1 complex in M phase Xenopus egg extracts controls both RCC1's enzymatic activity and partitioning between the chromatin-bound and soluble pools of RCC1. This mechanism is critical for spatial control of Ran-guanosine triphosphate (GTP) gradients that guide mitotic spindle assembly. Moreover, phosphorylation of RanBP1 drives changes in the dynamics of chromatin-bound RCC1 pools at the metaphase-anaphase transition. Our findings reveal an important mitotic role for RanBP1, controlling the spatial distribution and magnitude of mitotic Ran-GTP production and thereby ensuring accurate execution of Ran-dependent mitotic events.
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Affiliation(s)
- Michael Shaofei Zhang
- Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alexei Arnaoutov
- Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mary Dasso
- Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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28
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Neumayer G, Belzil C, Gruss OJ, Nguyen MD. TPX2: of spindle assembly, DNA damage response, and cancer. Cell Mol Life Sci 2014; 71:3027-47. [PMID: 24556998 PMCID: PMC11114040 DOI: 10.1007/s00018-014-1582-7] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/28/2014] [Accepted: 01/30/2014] [Indexed: 10/25/2022]
Abstract
For more than 15 years, TPX2 has been studied as a factor critical for mitosis and spindle assembly. These functions of TPX2 are attributed to its Ran-regulated microtubule-associated protein properties and to its control of the Aurora A kinase. Overexpressed in cancers, TPX2 is being established as marker for the diagnosis and prognosis of malignancies. During interphase, TPX2 resides preferentially in the nucleus where its function had remained elusive until recently. The latest finding that TPX2 plays a role in amplification of the DNA damage response, combined with the characterization of TPX2 knockout mice, open new perspectives to understand the biology of this protein. This review provides an historic overview of the discovery of TPX2 and summarizes its cytoskeletal and signaling roles with relevance to cancer therapies. Finally, the review aims to reconcile discrepancies between the experimental and pathological effects of TPX2 overexpression and advances new roles for compartmentalized TPX2.
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Affiliation(s)
- Gernot Neumayer
- Department of Clinical Neurosciences, Department of Cell Biology and Anatomy, Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, T2N 4N1, Canada,
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29
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Gheghiani L, Gavet O. Deciphering the spatio-temporal regulation of entry and progression through mitosis. Biotechnol J 2014; 9:213-23. [DOI: 10.1002/biot.201300194] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 09/19/2013] [Accepted: 12/03/2013] [Indexed: 11/07/2022]
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30
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Ran GTPase in nuclear envelope formation and cancer metastasis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:323-51. [PMID: 24563355 DOI: 10.1007/978-1-4899-8032-8_15] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ran is a small ras-related GTPase that controls the nucleocytoplasmic exchange of macromolecules across the nuclear envelope. It binds to chromatin early during nuclear formation and has important roles during the eukaryotic cell cycle, where it regulates mitotic spindle assembly, nuclear envelope formation and cell cycle checkpoint control. Like other GTPases, Ran relies on the cycling between GTP-bound and GDP-bound conformations to interact with effector proteins and regulate these processes. In nucleocytoplasmic transport, Ran shuttles across the nuclear envelope through nuclear pores. It is concentrated in the nucleus by an active import mechanism where it generates a high concentration of RanGTP by nucleotide exchange. It controls the assembly and disassembly of a range of complexes that are formed between Ran-binding proteins and cellular cargo to maintain rapid nuclear transport. Ran also has been identified as an essential protein in nuclear envelope formation in eukaryotes. This mechanism is dependent on importin-β, which regulates the assembly of further complexes important in this process, such as Nup107-Nup160. A strong body of evidence is emerging implicating Ran as a key protein in the metastatic progression of cancer. Ran is overexpressed in a range of tumors, such as breast and renal, and these perturbed levels are associated with local invasion, metastasis and reduced patient survival. Furthermore, tumors with oncogenic KRAS or PIK3CA mutations are addicted to Ran expression, which yields exciting future therapeutic opportunities.
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31
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Yokoyama H, Gruss OJ. New mitotic regulators released from chromatin. Front Oncol 2013; 3:308. [PMID: 24380075 PMCID: PMC3864359 DOI: 10.3389/fonc.2013.00308] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 12/04/2013] [Indexed: 12/13/2022] Open
Abstract
Faithful action of the mitotic spindle segregates duplicated chromosomes into daughter cells. Perturbations of this process result in chromosome mis-segregation, leading to chromosomal instability and cancer development. Chromosomes are not simply passengers segregated by spindle microtubules but rather play a major active role in spindle assembly. The GTP bound form of the Ran GTPase (RanGTP), produced around chromosomes, locally activates spindle assembly factors. Recent studies have uncovered that chromosomes organize mitosis beyond spindle formation. They distinctly regulate other mitotic events, such as spindle maintenance in anaphase, which is essential for chromosome segregation. Furthermore, the direct function of chromosomes is not only to produce RanGTP but, in addition, to release key mitotic regulators from chromatin. Chromatin-remodeling factors and nuclear pore complex proteins, which have established functions on chromatin in interphase, dissociate from mitotic chromatin and function in spindle assembly or maintenance. Thus, chromosomes actively organize their own segregation using chromatin-releasing mitotic regulators as well as RanGTP.
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Affiliation(s)
- Hideki Yokoyama
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance , Heidelberg , Germany
| | - Oliver J Gruss
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance , Heidelberg , Germany
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32
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Yokoyama H, Nakos K, Santarella-Mellwig R, Rybina S, Krijgsveld J, Koffa MD, Mattaj IW. CHD4 is a RanGTP-dependent MAP that stabilizes microtubules and regulates bipolar spindle formation. Curr Biol 2013; 23:2443-51. [PMID: 24268414 DOI: 10.1016/j.cub.2013.09.062] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 08/19/2013] [Accepted: 09/30/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Production of the GTP-bound form of the Ran GTPase (RanGTP) around chromosomes induces spindle assembly by activating nuclear localization signal (NLS)-containing proteins. Several NLS proteins have been identified as spindle assembly factors, but the complexity of the process led us to search for additional proteins with distinct roles in spindle assembly. RESULTS We identify a chromatin-remodeling ATPase, CHD4, as a RanGTP-dependent microtubule (MT)-associated protein (MAP). MT binding occurs via the region containing an NLS and chromatin-binding domains. In Xenopus egg extracts and cultured cells, CHD4 largely dissociates from mitotic chromosomes and partially localizes to the spindle. Immunodepletion of CHD4 from egg extracts significantly reduces the quantity of MTs produced around chromatin and prevents spindle assembly. CHD4 RNAi in both HeLa and Drosophila S2 cells induces defects in spindle assembly and chromosome alignment in early mitosis, leading to chromosome missegregation. Further analysis in egg extracts and in HeLa cells reveals that CHD4 is a RanGTP-dependent MT stabilizer. Moreover, the CHD4-containing NuRD complex promotes organization of MTs into bipolar spindles in egg extracts. Importantly, this function of CHD4 is independent of chromatin remodeling. CONCLUSIONS Our results uncover a new role for CHD4 as a MAP required for MT stabilization and involved in generating spindle bipolarity.
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Affiliation(s)
- Hideki Yokoyama
- European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany.
| | - Konstantinos Nakos
- Department of Molecular Biology and Genetics, Democritus University of Thrace, University Campus Dragana, Alexandroupolis 68100, Greece
| | | | - Sofia Rybina
- European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany
| | - Jeroen Krijgsveld
- European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany
| | - Maria D Koffa
- Department of Molecular Biology and Genetics, Democritus University of Thrace, University Campus Dragana, Alexandroupolis 68100, Greece.
| | - Iain W Mattaj
- European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany
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33
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Wu Z, Jiang Q, Clarke PR, Zhang C. Phosphorylation of Crm1 by CDK1-cyclin-B promotes Ran-dependent mitotic spindle assembly. J Cell Sci 2013; 126:3417-28. [PMID: 23729730 DOI: 10.1242/jcs.126854] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Mitotic spindle assembly in animal cells is orchestrated by a chromosome-dependent pathway that directs microtubule stabilization. RanGTP generated at chromosomes releases spindle assembly factors from inhibitory complexes with importins, the nuclear transport factors that facilitate protein import into the nucleus during interphase. In addition, the nuclear export factor Crm1 has been proposed to act as a mitotic effector of RanGTP through the localized assembly of protein complexes on the mitotic spindle, notably at centrosomes and kinetochores. It has been unclear, however, how the functions of nuclear transport factors are controlled during mitosis. Here, we report that human Crm1 is phosphorylated at serine 391 in mitosis by CDK1-cyclin-B (i.e. the CDK1 and cyclin B complex). Expression of Crm1 with serine 391 mutated to either non-phosphorylated or phosphorylation-mimicking residues indicates that phosphorylation directs the localization of Crm1 to the mitotic spindle and facilitates spindle assembly, microtubule stabilization and chromosome alignment. We find that phosphorylation of Crm1 at serine 391 enhances its RanGTP-dependent interaction with RanGAP1-RanBP2 and promotes their recruitment to the mitotic spindle. These results show that phosphorylation of Crm1 controls its molecular interactions, localization and function during mitosis, uncovering a new mechanism for the control of mitotic spindle assembly by CDK1-cyclin-B. We propose that nuclear transport factors are controlled during mitosis through the selection of specific molecular interactions by protein phosphorylation.
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Affiliation(s)
- Zhige Wu
- The MOE Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering, College of Life Sciences, Peking University, Beijing 100871, China
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34
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Bierbaum M, Bastiaens P. Cell cycle-dependent binding modes of the ran exchange factor RCC1 to chromatin. Biophys J 2013; 104:1642-51. [PMID: 23601311 PMCID: PMC3627872 DOI: 10.1016/j.bpj.2013.03.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 03/04/2013] [Accepted: 03/11/2013] [Indexed: 11/17/2022] Open
Abstract
The formation of an activity gradient of the small G-protein Ran around chromatin depends on the differential partitioning of the opposing enzyme activities of the Ran guanine nucleotide exchange factor RCC1 that resides on chromatin, and the cytoplasmic Ran GTPase activating protein RanGAP. We studied the time-dependent interaction kinetics between RCC1 and chromatin and the mobility of the Ran-RCC1 complex in living cells by fluorescence correlation spectroscopy to investigate whether binding of RCC1 to chromatin regulates the exchange activity of RCC1, and whether the stability of the RCC1-chromatin interaction is regulated during the cell cycle. We found that RCC1 mobility is dominated by two states: a highly mobile state that is trapped within chromatin, and a transiently immobilized state that is stabilized during mitosis. We show that only the immobilized state of RCC1 interacts with Ran and conclude that its guanine nucleotide exchange activity is restricted to specific sites on chromatin.
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Affiliation(s)
- Martin Bierbaum
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
- Faculty of Chemistry, Technical University Dortmund, Dortmund, Germany
| | - Philippe I.H. Bastiaens
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
- Faculty of Chemistry, Technical University Dortmund, Dortmund, Germany
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35
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Pfaff KL, King RW. Determinants of human cyclin B1 association with mitotic chromosomes. PLoS One 2013; 8:e59169. [PMID: 23505570 PMCID: PMC3594322 DOI: 10.1371/journal.pone.0059169] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 02/13/2013] [Indexed: 12/28/2022] Open
Abstract
Cyclin B1–CDK1 activity is essential for mitotic entry, but questions remain regarding how the activity of this kinase is spatially regulated. Previous studies showed that the cyclin B1 subunit localizes to several compartments of a mitotic cell, including the centrosomes, mitotic spindle, kinetochores and chromosomes via distinct sequence elements. Mitotic chromosome association occurs through the unstructured N-terminal domain of cyclin B1 and is independent of CDK1 binding. Here, we use live cell imaging of human cyclin B1 fused to GFP to precisely define the sequence elements within cyclin B1 that mediate its association with condensed mitotic chromosomes. We find that a short, evolutionarily conserved N-terminal motif is required for cyclin B1 to localize to mitotic chromosomes. We further reveal a role for arginine residues within and near the destruction box sequence in the chromosome association of cyclin B1. Additionally, our data suggest that sequences further downstream in cyclin B1, such as the cytoplasmic retention sequence and the cyclin box, may negatively modulate chromosome association. Because multiple basic residues are required for cyclin B1 association with mitotic chromosomes, electrostatic interactions with DNA may facilitate cyclin B1 localization to chromosomes.
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Affiliation(s)
- Kathleen L. Pfaff
- Harvard Medical School Department of Cell Biology, Boston, Massachusetts, United States of America
| | - Randall W. King
- Harvard Medical School Department of Cell Biology, Boston, Massachusetts, United States of America
- * E-mail:
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36
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Abstract
Centrosome- and chromatin-based microtubule nucleation pathways have been implicated in spindle assembly. Using total internal reflection fluorescent microscopy and Xenopus egg extracts, Petry et al. demonstrate that new microtubules can also nucleate and branch out from existing ones in animal cells.
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Affiliation(s)
- Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA.
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37
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Yenjerla M, Panopoulos A, Reynaud C, Fotedar R, Margolis RL. TD-60 is required for interphase cell cycle progression. Cell Cycle 2013; 12:837-41. [PMID: 23388455 DOI: 10.4161/cc.23821] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We previously identified TD-60 (RCC2) as a mitotic centromere-associated protein that is necessary for proper completion of mitosis. We now report that TD-60 is an essential regulator of cell cycle progression during interphase. siRNA suppression blocks progression of mammalian G₁/S phase cells and progression of G₂ cells into mitosis. Prolonged arrest occurs both in non-transformed cells and in transformed cells lacking functional p53. TD-60 associates with Rac1 and Arf6 and has recently been demonstrated to be an element of α5β1 integrin and cortactin interactomes. These associations with known elements of cell cycle control, together with our data, suggest that TD-60 is an essential component of one or more signaling pathways that drive cell cycle progression. During mitosis, TD-60 is required for correct assembly of the mitotic spindle and activation of key mitotic proteins. In contrast, in interphase TD-60 promotes cell cycle progression through what must be distinct mechanisms. TD-60 thus appears to be one of the growing categories of proteins that "moonlight," or have more than one distinct cellular function.
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Affiliation(s)
- Mythili Yenjerla
- Tumor Development Program, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
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38
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Hasegawa K, Ryu SJ, Kaláb P. Chromosomal gain promotes formation of a steep RanGTP gradient that drives mitosis in aneuploid cells. ACTA ACUST UNITED AC 2013; 200:151-61. [PMID: 23319601 PMCID: PMC3549973 DOI: 10.1083/jcb.201206142] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The chromosome-centered RanGTP gradient, which is strongly reduced in slow-growing normal cells, is amplified by chromosomal gain and is required for mitosis in rapidly growing aneuploid cells. Many mitotic factors were shown to be activated by Ran guanosine triphosphatase. Previous studies in Xenopus laevis egg extracts and in highly proliferative cells showed that mitotic chromosomes were surrounded by steep Ran guanosine triphosphate (GTP) concentration gradients, indicating that RanGTP-activated factors promote spindle assembly around chromosomes. However, the mitotic role of Ran in normal differentiated cells is not known. In this paper, we show that although the steep mitotic RanGTP gradients were present in rapidly growing cell lines and were required for chromosome congression in mitotic HeLa cells, the gradients were strongly reduced in slow-growing primary cells, such as HFF-1 fibroblasts. The overexpression of RCC1, the guanine nucleotide exchange factor for Ran, induced steeper mitotic RanGTP gradients in HFF-1 cells, showing the critical role of RCC1 levels in the regulation of mitosis by Ran. Remarkably, in vitro fusion of HFF-1 cells produced cells with steep mitotic RanGTP gradients comparable to HeLa cells, indicating that chromosomal gain can promote mitosis in aneuploid cancer cells via Ran.
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Affiliation(s)
- Keisuke Hasegawa
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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39
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Specific Cooperation Between Imp-α2 and Imp-β/Ketel in Spindle Assembly During Drosophila Early Nuclear Divisions. G3-GENES GENOMES GENETICS 2012; 2:1-14. [PMID: 22384376 PMCID: PMC3276186 DOI: 10.1534/g3.111.001073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 10/14/2011] [Indexed: 12/22/2022]
Abstract
The multifunctional factors Imp-α and Imp-β are involved in nuclear protein import, mitotic spindle dynamics, and nuclear membrane formation. Furthermore, each of the three members of the Imp-α family exerts distinct tasks during development. In Drosophila melanogaster, the imp-α2 gene is critical during oogenesis for ring canal assembly; specific mutations, which allow oogenesis to proceed normally, were found to block early embryonic mitosis. Here, we show that imp-α2 and imp-β genetically interact during early embryonic development, and we characterize the pattern of defects affecting mitosis in embryos laid by heterozygous imp-α2(D14) and imp-β(KetRE34) females. Embryonic development is arrested in these embryos but is unaffected in combinations between imp-β(KetRE34) and null mutations in imp-α1 or imp-α3. Furthermore, the imp-α2(D14)/imp-β(KetRE34) interaction could only be rescued by an imp-α2 transgene, albeit not imp-α1 or imp-α3, showing the exclusive imp-α2 function with imp-β. Use of transgenes carrying modifications in the major Imp-α2 domains showed the critical requirement of the nuclear localization signal binding (NLSB) site in this process. In the mutant embryos, we found metaphase-arrested mitoses made of enlarged spindles, suggesting an unrestrained activity of factors promoting spindle assembly. In accordance with this, we found that Imp-β(KetRE34) and Imp-β(KetD) bind a high level of RanGTP/GDP, and a deletion decreasing RanGTP level suppresses the imp-β(KetRE34) phenotype. These data suggest that a fine balance among Imp-α2, Imp-β, RanGTP, and the NLS cargos is critical for mitotic progression during early embryonic development.
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The site of RanGTP generation can act as an organizational cue for mitotic microtubules. Biol Cell 2011; 103:421-34. [PMID: 21692748 DOI: 10.1042/bc20100135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND INFORMATION RanGTP, which is generated on chromosomes during mitosis, is required for microtubule spindle assembly. Due to its restricted spatial generation within the cell it has been suggested that RanGTP acts as a spatial cue to organize site-specific spindle assembly within the cell. However, the absence of a detectable sharp gradient of RanGTP in somatic cells has led to suggestions that it may only act as a spatial cue in large cells and that it may operate as a general activator of the mitotic cytosol in somatic cells. RESULTS We report that ectopic generation of RanGTP at the plasma membrane stimulates the formation of organized arrays of microtubules at the plasma membrane. CONCLUSIONS These results suggest that the site of RanGTP generation in a mitotic somatic cell can generate critical spatial information that specifies where microtubules grow towards and where microtubules are organized. As RanGTP is normally generated on chromosomes, these results suggest that RanGTP may play an important role in specifying that spindle assembly occurs around chromosomes.
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Hwang HI, Ji JH, Jang YJ. Phosphorylation of Ran-binding protein-1 by Polo-like kinase-1 is required for interaction with Ran and early mitotic progression. J Biol Chem 2011; 286:33012-20. [PMID: 21813642 PMCID: PMC3190894 DOI: 10.1074/jbc.m111.255620] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 07/23/2011] [Indexed: 11/06/2022] Open
Abstract
Polo-like kinase-1 (Plk1) is essential for progression of mitosis and localizes to centrosomes, central spindles, midbody, and kinetochore. Ran, a small GTPase of the Ras superfamily, plays a role in microtubule dynamics and chromosome segregation during mitosis. Although Ran-binding protein-1 (RanBP1) has been reported as a regulator of RanGTPase for its mitotic functions, the action mechanism between Ran and RanBP1 during mitosis is still unknown. Here, we demonstrated in vitro and in vivo phosphorylation of RanBP1 by Plk1 as well as the importance of phosphorylation of RanBP1 in the interaction between Plk1 and Ran during early mitosis. Both phosphorylation-defective and N-terminal deletion mutant constructs of RanBP1 disrupted the interaction with Ran, and depletion of Plk1 also disrupted the formation of a complex between Ran and RanBP1. In addition, the results from both ectopic expression of phosphorylation-defective mutant construct and a functional complementation on RanBP1 deficiency with this mutant indicated that phosphorylation of RanBP1 by Plk1 might be crucial to microtubule nucleation and spindle assembly during mitosis.
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Affiliation(s)
- Hyo-In Hwang
- From the Laboratory of Cell Cycle and Signal Transduction, World Class University Research Department of Nanobiomedical Science and the Institute of Tissue Regeneration Engineering, Dankook University, 29 Anseo-Dong, Cheonan 330-714, Korea
| | - Jae-Hoon Ji
- From the Laboratory of Cell Cycle and Signal Transduction, World Class University Research Department of Nanobiomedical Science and the Institute of Tissue Regeneration Engineering, Dankook University, 29 Anseo-Dong, Cheonan 330-714, Korea
| | - Young-Joo Jang
- From the Laboratory of Cell Cycle and Signal Transduction, World Class University Research Department of Nanobiomedical Science and the Institute of Tissue Regeneration Engineering, Dankook University, 29 Anseo-Dong, Cheonan 330-714, Korea
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Wu F, Liu Y, Zhu Z, Huang H, Ding B, Wu J, Shi Y. The 1.9Å crystal structure of Prp20p from Saccharomyces cerevisiae and its binding properties to Gsp1p and histones. J Struct Biol 2011; 174:213-22. [DOI: 10.1016/j.jsb.2010.11.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 11/11/2010] [Accepted: 11/15/2010] [Indexed: 12/01/2022]
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Abstract
Roles of the GTPase Ran in cell life and division rely on a largely conserved mechanism, i.e. Ran's ability to interact with transport vectors. Modes of control of downstream factors, however, are diversified at particular times of the cell cycle. Specificity and fine-tuning emerge most clearly during mitosis. In the present article, we focus on the distinction between global mitotic control by the chromosomal Ran gradient and specific spatial and temporal control operated by localized Ran network members at sites of the mitotic apparatus in human cells.
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Kaláb P, Solc P, Motlík J. The role of RanGTP gradient in vertebrate oocyte maturation. Results Probl Cell Differ 2011; 53:235-67. [PMID: 21630149 DOI: 10.1007/978-3-642-19065-0_12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The maturation of vertebrate oocyte into haploid gamete, the egg, consists of two specialized asymmetric cell divisions with no intervening S-phase. Ran GTPase has an essential role in relaying the active role of chromosomes in their own segregation by the meiotic process. In addition to its conserved role as a key regulator of macromolecular transport between nucleus and cytoplasm, Ran has important functions during cell division, including in mitotic spindle assembly and in the assembly of nuclear envelope at the exit from mitosis. The cellular functions of Ran are mediated by RanGTP interactions with nuclear transport receptors (NTRs) related to importin β and depend on the existence of chromosome-centered RanGTP gradient. Live imaging with FRET biosensors indeed revealed the existence of RanGTP gradient throughout mouse oocyte maturation. NTR-dependent transport of cell cycle regulators including cyclin B1, Wee2, and Cdc25B between the oocyte cytoplasm and germinal vesicle (GV) is required for normal resumption of meiosis. After GVBD in mouse oocytes, RanGTP gradient is required for timely meiosis I (MI) spindle assembly and provides long-range signal directing egg cortex differentiation. However, RanGTP gradient is not required for MI spindle migration and may be dispensable for MI spindle function in chromosome segregation. In contrast, MII spindle assembly and function in maturing mouse and Xenopus laevis eggs depend on RanGTP gradient, similar to X. laevis MII-derived egg extracts.
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Affiliation(s)
- Petr Kaláb
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892-4256, USA.
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Ciciarello M, Roscioli E, Di Fiore B, Di Francesco L, Sobrero F, Bernard D, Mangiacasale R, Harel A, Schininà ME, Lavia P. Nuclear reformation after mitosis requires downregulation of the Ran GTPase effector RanBP1 in mammalian cells. Chromosoma 2010; 119:651-68. [PMID: 20658144 DOI: 10.1007/s00412-010-0286-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 06/28/2010] [Accepted: 06/30/2010] [Indexed: 11/26/2022]
Abstract
The GTPase Ran regulates nucleocytoplasmic transport in interphase and spindle organisation in mitosis via effectors of the importin beta superfamily. Ran-binding protein 1 (RanBP1) regulates guanine nucleotide turnover on Ran, as well as its interactions with effectors. Unlike other Ran network members that are steadily expressed, RanBP1 abundance is modulated during the mammalian cell cycle, peaking in mitosis and declining at mitotic exit. Here, we show that RanBP1 downregulation takes place in mid to late telophase, concomitant with the reformation of nuclei. Mild RanBP1 overexpression in murine cells causes RanBP1 to persist in late mitosis and hinders a set of events underlying the telophase to interphase transition, including chromatin decondensation, nuclear expansion and nuclear lamina reorganisation. Moreover, the reorganisation of nuclear pores fails associated with defective nuclear relocalisation of NLS cargoes. Co-expression of importin beta, together with RanBP1, however mitigates these defects. Thus, RanBP1 downregulation is required for nuclear reorganisation pathways operated by importin beta after mitosis.
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Affiliation(s)
- Marilena Ciciarello
- CNR National Research Council, Institute of Molecular Biology and Pathology, c/o Sapienza University of Rome, Rome, 00185, Italy
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Chan KS, Wong CH, Huang YF, Li HY. Survivin withdrawal by nuclear export failure as a physiological switch to commit cells to apoptosis. Cell Death Dis 2010; 1:e57. [PMID: 21364662 PMCID: PMC3032555 DOI: 10.1038/cddis.2010.34] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 05/26/2010] [Accepted: 06/10/2010] [Indexed: 11/16/2022]
Abstract
Apoptosis is a tightly controlled process regulated by many signaling pathways; however, the mechanisms and cellular events that decide whether a cell lives or dies remain poorly understood. Here we showed that when a cell is under apoptotic stress, the prosurvival protein Survivin redistributes from the cytoplasm to the nucleus, thus acting as a physiological switch to commit the cell to apoptosis. The nuclear relocalization of Survivin is a result of inefficient assembly of functional RanGTP-CRM1-Survivin export complex due to apoptotic RanGTP gradient collapse. Subsequently, Survivin undergoes ubiquitination, which not only physically prevents its diffusion back to the cytoplasm but also facilitates its degradation. Together, this spatial and functional regulation of Survivin abolishes its cytoprotective effect toward the apoptotic executors and thus commits a cell to apoptosis. Our data indicate that the withdrawal of Survivin is a novel and active physiological regulatory mechanism that tilts the survival balance and promotes the progression of apoptosis.
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Affiliation(s)
- K-S Chan
- Division of Molecular and Cell Biology, School of Biological Sciences, College of Science, Nanyang Technological University, Singapore 637551, Singapore
| | - C-H Wong
- Division of Molecular and Cell Biology, School of Biological Sciences, College of Science, Nanyang Technological University, Singapore 637551, Singapore
| | - Y-F Huang
- Division of Molecular and Cell Biology, School of Biological Sciences, College of Science, Nanyang Technological University, Singapore 637551, Singapore
| | - H-Y Li
- Division of Molecular and Cell Biology, School of Biological Sciences, College of Science, Nanyang Technological University, Singapore 637551, Singapore
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Expression of targeting protein for Xenopus kinesin-like protein 2 is associated with progression of human malignant astrocytoma. Brain Res 2010; 1352:200-7. [PMID: 20599806 DOI: 10.1016/j.brainres.2010.06.060] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 06/23/2010] [Accepted: 06/23/2010] [Indexed: 12/30/2022]
Abstract
In humans, the targeting protein for Xenopus kinesin-like protein 2 (TPX2) is a cell cycle-associated protein, and altered TPX2 expression has been found in various malignancies. However, the contribution of TPX2 expression to astrocytoma progression is unclear. The aim of this study was to investigate TPX2 expression in human astrocytoma samples and cell lines. TPX2 protein expression was detected in the nucleus of astrocytoma tissues by immunohistochemistry and immunofluorescence staining. Real-time PCR and Western blot analysis showed that the expression levels of TPX2 were higher in high-grade astrocytoma tissues and cell lines than that in low-grade astrocytoma tissues and normal cell lines. Immunohistochemical analysis of tumor tissues from 52 patients with astrocytoma showed that TPX2 over-expression was significantly associated with decreased patient survival. In addition, down-regulation of the TPX2 gene by RNA interference inhibited proliferation of U87 cells. TPX2 gene silencing also increased early-stage apoptosis in U87 cells. Western blotting and real-time PCR showed changes in the protein and mRNA expression of Aurora A, Ran, p53, c-Myc and cyclin B1 in U87 cells that had been transfected with pSUPER/TPX2/siRNA. These data suggest that TPX2 expression is associated with the progression of malignant astrocytoma.
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Hitakomate E, Hood FE, Sanderson HS, Clarke PR. The methylated N-terminal tail of RCC1 is required for stabilisation of its interaction with chromatin by Ran in live cells. BMC Cell Biol 2010; 11:43. [PMID: 20565941 PMCID: PMC2898669 DOI: 10.1186/1471-2121-11-43] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 06/21/2010] [Indexed: 11/30/2022] Open
Abstract
Background Regulator of chromosome condensation 1 (RCC1) is the guanine nucleotide exchange factor for Ran GTPase. Localised generation of Ran-GTP by RCC1 on chromatin is critical for nucleocytoplasmic transport, mitotic spindle assembly and nuclear envelope formation. Both the N-terminal tail of RCC1 and its association with Ran are important for its interaction with chromatin in cells. In vitro, the association of Ran with RCC1 induces a conformational change in the N-terminal tail that promotes its interaction with DNA. Results We have investigated the mechanism of the dynamic interaction of the α isoform of human RCC1 (RCC1α) with chromatin in live cells using fluorescence recovery after photobleaching (FRAP) of green fluorescent protein (GFP) fusions. We show that the N-terminal tail stabilises the interaction of RCC1α with chromatin and this function can be partially replaced by another lysine-rich nuclear localisation signal. Removal of the tail prevents the interaction of RCC1α with chromatin from being stabilised by RanT24N, a mutant that binds stably to RCC1α. The interaction of RCC1α with chromatin is destabilised by mutation of lysine 4 (K4Q), which abolishes α-N-terminal methylation, and this interaction is no longer stabilised by RanT24N. However, α-N-terminal methylation of RCC1α is not regulated by the binding of RanT24N. Conversely, the association of Ran with precipitated RCC1α does not require the N-terminal tail of RCC1α or its methylation. The mobility of RCC1α on chromatin is increased by mutation of aspartate 182 (D182A), which inhibits guanine-nucleotide exchange activity, but RCC1αD182A can still bind nucleotide-free Ran and its interaction with chromatin is stabilised by RanT24N. Conclusions These results show that the stabilisation of the dynamic interaction of RCC1α with chromatin by Ran in live cells requires the N-terminal tail of RCC1α. α-N-methylation is not regulated by formation of the binary complex with Ran, but it promotes chromatin binding through the tail. This work supports a model in which the association of RCC1α with chromatin is promoted by a conformational change in the α-N-terminal methylated tail that is induced allosterically in the binary complex with Ran.
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Affiliation(s)
- Ekarat Hitakomate
- Biomedical Research Institute, School of Medicine, College of Medicine, Dentistry and Nursing, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK
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Abstract
Eukaryotic cell division uses morphologically different forms of mitosis, referred to as open, partially open and closed mitosis, for accurate chromosome segregation and proper partitioning of other cellular components such as endomembranes and cell fate determinants. Recent studies suggest that the spindle matrix provides a conserved strategy to coordinate the segregation of genetic material and the partitioning of the rest of the cellular contents in all three forms of mitosis.
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Affiliation(s)
- Yixian Zheng
- Department of Embryology, Carnegie Institute for Science, Baltimore, Maryland 21218, USA.
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Abstract
The transition to mitosis requires extensive nuclear and cytoplasmic rearrangements that must be spatially and temporally coordinated. In this issue, Gavet and Pines (2010a. J. Cell Biol. doi:10.1083/jcb.200909144) report on a simple yet elegant mechanism as to how this is achieved. By monitoring the activity of cyclin B-Cdk1 in real time, the authors show that concomitant with its activation in the cytoplasm, the kinase complex is rapidly imported into the nucleus by modifying the activity of the nucleocytoplasmic transport machinery. Thus, cyclin B-Cdk1 activates its own pump to get into the nucleus.
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Affiliation(s)
- Arne Lindqvist
- Department of Medical Oncology, University Medical Center Utrecht, 3584CG Utrecht, Netherlands.
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