1
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Veldsink AC, Gallardo P, Lusk CP, Veenhoff LM. Changing the guard-nuclear pore complex quality control. FEBS Lett 2023; 597:2739-2749. [PMID: 37715940 DOI: 10.1002/1873-3468.14739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/31/2023] [Accepted: 08/31/2023] [Indexed: 09/18/2023]
Abstract
The integrity of the nuclear envelope depends on the function of nuclear pore complexes (NPCs), transport channels that control macromolecular traffic between the nucleus and cytosol. The central importance of NPCs suggests the existence of quality control (QC) mechanisms that oversee their assembly and function. In this perspective, we emphasize the challenges associated with NPC assembly and the need for QC mechanisms that operate at various stages of an NPC's life. This includes cytosolic preassembly QC that helps enforce key nucleoporin-nucleoporin interactions and their ultimate stoichiometry in the NPC in addition to mechanisms that monitor aberrant fusion of the inner and outer nuclear membranes. Furthermore, we discuss whether and how these QC mechanisms may operate to sense faulty mature NPCs to facilitate their repair or removal. The so far uncovered mechanisms for NPC QC provide fertile ground for future research that not only benefits a better understanding of the vital role that NPCs play in cellular physiology but also how loss of NPC function and/or these QC mechanisms might be an input to aging and disease.
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Affiliation(s)
- Annemiek C Veldsink
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, The Netherlands
| | - Paola Gallardo
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, The Netherlands
| | - C Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, CT, New Haven, USA
| | - Liesbeth M Veenhoff
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, The Netherlands
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2
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Nong JS, Zhou X, Liu JQ, Luo JZ, Huang JM, Xie HX, Yang KJ, Wang J, Ye XP, Peng T. Nucleoporin 107 is a prognostic biomarker in hepatocellular carcinoma associated with immune infiltration. Cancer Med 2023; 12:10990-11009. [PMID: 36952458 DOI: 10.1002/cam4.5807] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/16/2023] [Accepted: 02/22/2023] [Indexed: 03/25/2023] Open
Abstract
OBJECTIVE To assess the diagnostic value and clinical significance of nucleoporin 107 (NUP107) in hepatocellular carcinoma (HCC), and explore the possible mechanisms. METHODS The transcriptomic and clinical data of HCC patients were retrieved from The Cancer Genome Atlas (TCGA) and GEO databases. Tissue specimens were collected from HCC patients in the Guangxi area. According to the expression levels and prognostic characteristics of NUP107, ROC curves and nomogram models were constructed using the R package. RESULTS NUP107 was highly expressed in 26 human cancers including HCC, and was associated with advanced HCC staging and worse prognosis. NUP107 showed satisfactory ability to predict the prognosis of HCC patients (AUC >0.8). Results of gene set enrichment analysis (GSEA) further showed that NUP107 was mainly associated with cell cycle-related pathways such as the cell cycle, DNA replication, G2M checkpoint, E2F target, and mitotic spindle. In addition, NUP107 was also associated with immune infiltration in HCC and showed significant positive correlation with immune checkpoints (PD-L1 and TIM-3).
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Affiliation(s)
- Ju-Sen Nong
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Xin Zhou
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Jun-Qi Liu
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Jian-Zhu Luo
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Jia-Mi Huang
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Hai-Xiang Xie
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Ke-Jian Yang
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Jing Wang
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Xin-Ping Ye
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
| | - Tao Peng
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
- Key Laboratory of Early Prevention & Treatment for Regional High Frequency Tumor, Ministry of Education, Guangxi Medical University, Nanning, People's Republic of China
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3
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Varberg JM, Unruh JR, Bestul AJ, Khan AA, Jaspersen SL. Quantitative analysis of nuclear pore complex organization in Schizosaccharomyces pombe. Life Sci Alliance 2022; 5:5/7/e202201423. [PMID: 35354597 PMCID: PMC8967992 DOI: 10.26508/lsa.202201423] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 01/06/2023] Open
Abstract
Characterization of nuclear pores in Schizosaccharomyces pombe identifies regions of heterogeneous NPC density and composition and shows that NPCs are excluded near the spindle pole body by Lem2-mediated centromere tethering. The number, distribution, and composition of nuclear pore complexes (NPCs) in the nuclear envelope varies between cell types and changes during cellular differentiation and in disease. To understand how NPC density and organization are controlled, we analyzed the NPC number and distribution in the fission yeast Schizosaccharomyces pombe using structured illumination microscopy. The small size of yeast nuclei, genetic features of fungi, and our robust image analysis pipeline allowed us to study NPCs in intact nuclei under multiple conditions. Our data revealed that NPC density is maintained across a wide range of nuclear sizes. Regions of reduced NPC density are observed over the nucleolus and surrounding the spindle pole body (SPB). Lem2-mediated tethering of the centromeres to the SPB is required to maintain NPC exclusion near SPBs. These findings provide a quantitative understanding of NPC number and distribution in S. pombe and show that interactions between the centromere and the nuclear envelope influences local NPC distribution.
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Affiliation(s)
| | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Andrew J Bestul
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Azqa A Khan
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO, USA .,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
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4
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Hamed M, Antonin W. Dunking into the Lipid Bilayer: How Direct Membrane Binding of Nucleoporins Can Contribute to Nuclear Pore Complex Structure and Assembly. Cells 2021; 10:3601. [PMID: 34944108 PMCID: PMC8700311 DOI: 10.3390/cells10123601] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 02/07/2023] Open
Abstract
Nuclear pore complexes (NPCs) mediate the selective and highly efficient transport between the cytoplasm and the nucleus. They are embedded in the two membrane structure of the nuclear envelope at sites where these two membranes are fused to pores. A few transmembrane proteins are an integral part of NPCs and thought to anchor these complexes in the nuclear envelope. In addition, a number of nucleoporins without membrane spanning domains interact with the pore membrane. Here we review our current knowledge of how these proteins interact with the membrane and how this interaction can contribute to NPC assembly, stability and function as well as shaping of the pore membrane.
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Affiliation(s)
| | - Wolfram Antonin
- Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, 52074 Aachen, Germany;
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5
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Zimmerli CE, Allegretti M, Rantos V, Goetz SK, Obarska-Kosinska A, Zagoriy I, Halavatyi A, Hummer G, Mahamid J, Kosinski J, Beck M. Nuclear pores dilate and constrict in cellulo. Science 2021; 374:eabd9776. [PMID: 34762489 DOI: 10.1126/science.abd9776] [Citation(s) in RCA: 143] [Impact Index Per Article: 47.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Christian E Zimmerli
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.,Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, 69120 Heidelberg, Germany.,Department of Molecular Sociology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Matteo Allegretti
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.,Department of Molecular Sociology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Vasileios Rantos
- Centre for Structural Systems Biology (CSSB), 22607 Hamburg, Germany.,EMBL Hamburg, 22607 Hamburg, Germany
| | - Sara K Goetz
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.,Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, 69120 Heidelberg, Germany
| | - Agnieszka Obarska-Kosinska
- Department of Molecular Sociology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany.,EMBL Hamburg, 22607 Hamburg, Germany
| | - Ievgeniia Zagoriy
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | | | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany.,Institute of Biophysics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Jan Kosinski
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.,Centre for Structural Systems Biology (CSSB), 22607 Hamburg, Germany.,EMBL Hamburg, 22607 Hamburg, Germany
| | - Martin Beck
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.,Department of Molecular Sociology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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6
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Borah S, Thaller DJ, Hakhverdyan Z, Rodriguez EC, Isenhour AW, Rout MP, King MC, Lusk CP. Heh2/Man1 may be an evolutionarily conserved sensor of NPC assembly state. Mol Biol Cell 2021; 32:1359-1373. [PMID: 34010011 PMCID: PMC8694041 DOI: 10.1091/mbc.e20-09-0584] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Integral membrane proteins of the Lap2-emerin-MAN1 (LEM) family have emerged as important components of the inner nuclear membrane (INM) required for the functional and physical integrity of the nuclear envelope. However, like many INM proteins, there is limited understanding of the biochemical interaction networks that enable LEM protein function. Here, we show that Heh2/Man1 can interact with major scaffold components of the nuclear pore complex (NPC), specifically the inner ring complex (IRC), in evolutionarily distant yeasts. Although an N-terminal domain is required for Heh2 targeting to the INM, we demonstrate that more stable interactions with the NPC are mediated by a C-terminal winged helix (WH) domain, thus decoupling INM targeting and NPC binding. Inhibiting Heh2's interactions with the NPC by deletion of the Heh2 WH domain leads to NPC clustering. Interestingly, Heh2's association with NPCs can also be disrupted by knocking out several outer ring nucleoporins. Thus, Heh2's interaction with NPCs depends on the structural integrity of both major NPC scaffold complexes. We propose a model in which Heh2 acts as a sensor of NPC assembly state, which may be important for NPC quality control mechanisms and the segregation of NPCs during cell division.
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Affiliation(s)
- Sapan Borah
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | - David J Thaller
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | | | - Elisa C Rodriguez
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | - Anthony W Isenhour
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | | | - Megan C King
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | - C Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
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7
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Fukuda T, Sofyantoro F, Tai YT, Chia KH, Matsuda T, Murase T, Morozumi Y, Tatebe H, Kanki T, Shiozaki K. Tripartite suppression of fission yeast TORC1 signaling by the GATOR1-Sea3 complex, the TSC complex, and Gcn2 kinase. eLife 2021; 10:60969. [PMID: 33534698 PMCID: PMC7857730 DOI: 10.7554/elife.60969] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 01/22/2021] [Indexed: 01/07/2023] Open
Abstract
Mammalian target of rapamycin complex 1 (TORC1) is controlled by the GATOR complex composed of the GATOR1 subcomplex and its inhibitor, the GATOR2 subcomplex, sensitive to amino acid starvation. Previously, we identified fission yeast GATOR1 that prevents deregulated activation of TORC1 (Chia et al., 2017). Here, we report identification and characterization of GATOR2 in fission yeast. Unexpectedly, the GATOR2 subunit Sea3, an ortholog of mammalian WDR59, is physically and functionally proximal to GATOR1, rather than GATOR2, attenuating TORC1 activity. The fission yeast GATOR complex is dispensable for TORC1 regulation in response to amino acid starvation, which instead activates the Gcn2 pathway to inhibit TORC1 and induce autophagy. On the other hand, nitrogen starvation suppresses TORC1 through the combined actions of the GATOR1-Sea3 complex, the Gcn2 pathway, and the TSC complex, another conserved TORC1 inhibitor. Thus, multiple, parallel signaling pathways implement negative regulation of TORC1 to ensure proper cellular starvation responses.
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Affiliation(s)
- Tomoyuki Fukuda
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Fajar Sofyantoro
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.,Faculty of Biology, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Yen Teng Tai
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Kim Hou Chia
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Takato Matsuda
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Takaaki Murase
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Hisashi Tatebe
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Tomotake Kanki
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.,Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, United States
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8
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Whalen JM, Freudenreich CH. Location, Location, Location: The Role of Nuclear Positioning in the Repair of Collapsed Forks and Protection of Genome Stability. Genes (Basel) 2020; 11:E635. [PMID: 32526925 PMCID: PMC7348918 DOI: 10.3390/genes11060635] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 05/29/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022] Open
Abstract
Components of the nuclear pore complex (NPC) have been shown to play a crucial role in protecting against replication stress, and recovery from some types of stalled or collapsed replication forks requires movement of the DNA to the NPC in order to maintain genome stability. The role that nuclear positioning has on DNA repair has been investigated in several systems that inhibit normal replication. These include structure forming sequences (expanded CAG repeats), protein mediated stalls (replication fork barriers (RFBs)), stalls within the telomere sequence, and the use of drugs known to stall or collapse replication forks (HU + MMS or aphidicolin). Recently, the mechanism of relocation for collapsed replication forks to the NPC has been elucidated. Here, we will review the types of replication stress that relocate to the NPC, the current models for the mechanism of relocation, and the currently known protective effects of this movement.
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Affiliation(s)
- Jenna M. Whalen
- Department of Biology, Tufts University, Medford, MA 02155, USA;
| | - Catherine H. Freudenreich
- Department of Biology, Tufts University, Medford, MA 02155, USA;
- Program in Genetics, Tufts University, Boston, MA 02111, USA
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9
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Li C, Liu L, Teo ZWN, Shen L, Yu H. Nucleoporin 160 Regulates Flowering through Anchoring HOS1 for Destabilizing CO in Arabidopsis. PLANT COMMUNICATIONS 2020; 1:100033. [PMID: 33367234 PMCID: PMC7748013 DOI: 10.1016/j.xplc.2020.100033] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 05/26/2023]
Abstract
Nuclear pore complexes (NPCs), which comprise multiple copies of nucleoporins (Nups), are large protein assemblies embedded in the nuclear envelope connecting the nucleus and cytoplasm. Although it has been known that Nups affect flowering in Arabidopsis, the underlying mechanisms are poorly understood. Here, we show that loss of function of Nucleoporin 160 (Nup160) leads to increased abundance of CONSTANS (CO) protein and the resulting upregulation of FLOWERING LOCUS T (FT) specifically in the morning. We demonstrate that Nup160 regulates CO protein stability through affecting NPC localization of an E3-ubiquitin ligase, HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES1 (HOS1), which destabilizes CO protein in the morning period. Taken together, these results provide a mechanistic understanding of Nup function in the transition from vegetative to reproductive growth, suggesting that deposition of HOS1 at NPCs by Nup160 is essential for preventing precocious flowering in response to photoperiod in Arabidopsis.
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Affiliation(s)
- Chunying Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore
| | - Lu Liu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore
| | - Zhi Wei Norman Teo
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore
| | - Lisha Shen
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore
| | - Hao Yu
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore
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10
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Salas-Pino S, Daga RR. Spatiotemporal control of spindle disassembly in fission yeast. Cell Mol Life Sci 2019; 76:3543-3551. [PMID: 31129857 PMCID: PMC11105212 DOI: 10.1007/s00018-019-03139-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/29/2019] [Accepted: 05/07/2019] [Indexed: 12/20/2022]
Abstract
Maintenance of genomic stability during cell division is one of the most important cellular tasks, and it critically depends on the faithful replication of the genetic material and its equal partitioning into daughter cells, gametes, or spores in the case of yeasts. Defective mitotic spindle assembly and disassembly both result in changes in cellular ploidy that ultimately impinge proliferation fitness and might increase tumor malignancy. Although a great progress has been made in understanding how spindles are assembled to orchestrate chromosome segregation, much less is known about how they are disassembled once completed their function. Here, we review two recently uncovered mechanisms of spindle disassembly that operate at different stages of the fission yeast life cycle.
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Affiliation(s)
- Silvia Salas-Pino
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucia, Carretera de Utrera, km1, 41013, Seville, Spain.
| | - Rafael R Daga
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucia, Carretera de Utrera, km1, 41013, Seville, Spain.
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11
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Asymmetrical localization of Nup107-160 subcomplex components within the nuclear pore complex in fission yeast. PLoS Genet 2019; 15:e1008061. [PMID: 31170156 PMCID: PMC6553703 DOI: 10.1371/journal.pgen.1008061] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 03/01/2019] [Indexed: 01/05/2023] Open
Abstract
The nuclear pore complex (NPC) forms a gateway for nucleocytoplasmic transport. The outer ring protein complex of the NPC (the Nup107-160 subcomplex in humans) is a key component for building the NPC. Nup107-160 subcomplexes are believed to be symmetrically localized on the nuclear and cytoplasmic sides of the NPC. However, in S. pombe immunoelectron and fluorescence microscopic analyses revealed that the homologous components of the human Nup107-160 subcomplex had an asymmetrical localization: constituent proteins spNup132 and spNup107 were present only on the nuclear side (designated the spNup132 subcomplex), while spNup131, spNup120, spNup85, spNup96, spNup37, spEly5 and spSeh1 were localized only on the cytoplasmic side (designated the spNup120 subcomplex), suggesting the complex was split into two pieces at the interface between spNup96 and spNup107. This contrasts with the symmetrical localization reported in other organisms. Fusion of spNup96 (cytoplasmic localization) with spNup107 (nuclear localization) caused cytoplasmic relocalization of spNup107. In this strain, half of the spNup132 proteins, which interact with spNup107, changed their localization to the cytoplasmic side of the NPC, leading to defects in mitotic and meiotic progression similar to an spNup132 deletion strain. These observations suggest the asymmetrical localization of the outer ring spNup132 and spNup120 subcomplexes of the NPC is necessary for normal cell cycle progression in fission yeast. The nuclear pore complexes (NPCs) form gateways to transport intracellular molecules between the nucleus and the cytoplasm across the nuclear envelope. The Nup107-160 subcomplex, that forms nuclear and cytoplasmic outer rings, is a key complex responsible for building the NPC by symmetrical localization on the nuclear and cytoplasmic sides of the nuclear pore. This structural characteristic was found in various organisms including humans and budding yeasts, and therefore believed to be common among “all” eukaryotes. However, in this paper, we revealed an asymmetrical localization of the homologous components of the human Nup107-160 subcomplex in fission yeast by immunoelectron and fluorescence microscopic analyses: in this organism, the Nup107-160 subcomplex is split into two pieces, and each of the split pieces is differentially distributed to the nuclear and cytoplasmic side of the NPC: one piece is only in the nuclear side while the other piece is only in the cytoplasmic side. This contrasts with the symmetrical localization reported in other organisms. In addition, we confirmed that the asymmetrical configuration of the outer ring structure is necessary for cell cycle progression in fission yeast. This study provides notions of diverse structures and functions of NPCs evolved in eukaryotes.
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12
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Affiliation(s)
- Guillaume Holzer
- Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, Aachen, Germany
| | - Wolfram Antonin
- Institute of Biochemistry and Molecular Cell Biology, Medical School, RWTH Aachen University, Aachen, Germany
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13
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Systematic analysis reveals the prevalence and principles of bypassable gene essentiality. Nat Commun 2019; 10:1002. [PMID: 30824696 PMCID: PMC6397241 DOI: 10.1038/s41467-019-08928-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 02/07/2019] [Indexed: 12/12/2022] Open
Abstract
Gene essentiality is a variable phenotypic trait, but to what extent and how essential genes can become dispensable for viability remain unclear. Here, we investigate 'bypass of essentiality (BOE)' - an underexplored type of digenic genetic interaction that renders essential genes dispensable. Through analyzing essential genes on one of the six chromosome arms of the fission yeast Schizosaccharomyces pombe, we find that, remarkably, as many as 27% of them can be converted to non-essential genes by BOE interactions. Using this dataset we identify three principles of essentiality bypass: bypassable essential genes tend to have lower importance, tend to exhibit differential essentiality between species, and tend to act with other bypassable genes. In addition, we delineate mechanisms underlying bypassable essentiality, including the previously unappreciated mechanism of dormant redundancy between paralogs. The new insights gained on bypassable essentiality deepen our understanding of genotype-phenotype relationships and will facilitate drug development related to essential genes.
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14
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Cantwell H, Nurse P. A systematic genetic screen identifies essential factors involved in nuclear size control. PLoS Genet 2019; 15:e1007929. [PMID: 30759079 PMCID: PMC6391033 DOI: 10.1371/journal.pgen.1007929] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 02/26/2019] [Accepted: 01/02/2019] [Indexed: 12/15/2022] Open
Abstract
Nuclear size correlates with cell size, but the mechanism by which this scaling is achieved is not known. Here we screen fission yeast gene deletion mutants to identify essential factors involved in this process. Our screen has identified 25 essential factors that alter nuclear size, and our analysis has implicated RNA processing and LINC complexes in nuclear size control. This study has revealed lower and more extreme higher nuclear size phenotypes and has identified global cellular processes and specific structural nuclear components important for nuclear size control. As cells grow and divide, the size of the nucleus is generally maintained as a fixed proportion of cell size. The mechanism by which this nuclear/cytoplasmic ratio is maintained is unclear. Previous studies have suggested that essential gene products may be important for nuclear size control. Therefore, we have exploited the genetic tractability of fission yeast to carry out a systematic genetic screen of deleted essential genes to identify those with aberrant nuclear size phenotypes. Our study has revealed 25 novel genes that influence nuclear size and our bioinformatic analyses have implicated both RNA processing and protein complexes connecting nuclear chromatin to the cytoskeleton in nuclear size control. Our work sheds light on the biological processes that contribute to nuclear size control in fission yeast contributing to our mechanistic understanding of nuclear scaling, a biological phenomenon that is conserved through evolution.
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Affiliation(s)
- Helena Cantwell
- Cell Cycle Laboratory, The Francis Crick Institute, London, United Kingdom
- * E-mail:
| | - Paul Nurse
- Cell Cycle Laboratory, The Francis Crick Institute, London, United Kingdom
- Laboratory of Yeast Genetics and Cell Biology, Rockefeller University, New York, United States of America
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15
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Guan Y, Gao X, Tang Q, Huang L, Gao S, Yu S, Huang J, Li J, Zhou D, Zhang Y, Shi D, Liang D, Liu Y, Li L, Cui Y, Xu L, Chen YH. Nucleoporin 107 facilitates the nuclear export of Scn5a mRNA to regulate cardiac bioelectricity. J Cell Mol Med 2018; 23:1448-1457. [PMID: 30506890 PMCID: PMC6349201 DOI: 10.1111/jcmm.14051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 10/13/2018] [Accepted: 11/05/2018] [Indexed: 01/02/2023] Open
Abstract
Nucleoporins (Nups) are known to be functional in nucleo‐cytoplasmic transport, but the roles of nucleoporins in nonproliferating cells, such as cardiac myocytes, are still poorly understood. In this study, we report that Nup107 regulates cardiac bioelectricity by controlling the nucleo‐cytoplasmic trafficking of Scn5a mRNA. Overexpression of Nup107 induced the protein expression of Scn5a rather than that of other ion channels, with no effects of their mRNA levels. The analysis for the protein production demonstrated Nup107‐facilitated transport of Scn5a mRNA. Using RIP‐PCR and luciferase assay, we found that the 5′‐UTR of Scn5a mRNA was not involved in the interaction, whereas the spatial interaction between Nup107 protein and Scn5a mRNA was formed when Scn5a mRNA passing through the nuclear pore. Functionally, Nup107 overexpression in neonatal rat ventricle myocytes significantly increased the currents of Scn5a‐encoded INa channel. Moreover, the close correlation between Nup107 and Nav1.5 protein expression was observed in cardiomycytes and heart tissues subjected to hypoxia and ischaemic insults, suggesting a fast regulation of Nup107 on Nav1.5 channel in cardiac myocytes in a posttranscriptional manner. These findings may provide insights into the emergent control of cardiac electrophysiology through Nup‐mediated modulation of ion channels.
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Affiliation(s)
- Yi Guan
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Xueting Gao
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Qiuyu Tang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Lin Huang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Siyun Gao
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Shuai Yu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Jiale Huang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jun Li
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Daizhan Zhou
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yangyang Zhang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Dan Shi
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Dandan Liang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi Liu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Li Li
- Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Yingyu Cui
- Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Liang Xu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi-Han Chen
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
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16
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Bao XX, Spanos C, Kojidani T, Lynch EM, Rappsilber J, Hiraoka Y, Haraguchi T, Sawin KE. Exportin Crm1 is repurposed as a docking protein to generate microtubule organizing centers at the nuclear pore. eLife 2018; 7:e33465. [PMID: 29809148 PMCID: PMC6008054 DOI: 10.7554/elife.33465] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 05/21/2018] [Indexed: 01/04/2023] Open
Abstract
Non-centrosomal microtubule organizing centers (MTOCs) are important for microtubule organization in many cell types. In fission yeast Schizosaccharomyces pombe, the protein Mto1, together with partner protein Mto2 (Mto1/2 complex), recruits the γ-tubulin complex to multiple non-centrosomal MTOCs, including the nuclear envelope (NE). Here, we develop a comparative-interactome mass spectrometry approach to determine how Mto1 localizes to the NE. Surprisingly, we find that Mto1, a constitutively cytoplasmic protein, docks at nuclear pore complexes (NPCs), via interaction with exportin Crm1 and cytoplasmic FG-nucleoporin Nup146. Although Mto1 is not a nuclear export cargo, it binds Crm1 via a nuclear export signal-like sequence, and docking requires both Ran in the GTP-bound state and Nup146 FG repeats. In addition to determining the mechanism of MTOC formation at the NE, our results reveal a novel role for Crm1 and the nuclear export machinery in the stable docking of a cytoplasmic protein complex at NPCs.
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Affiliation(s)
- Xun X Bao
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Christos Spanos
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Tomoko Kojidani
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Department of Chemical and Biological Sciences, Faculty of ScienceJapan Women’s UniversityTokyoJapan
| | - Eric M Lynch
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
- Department of BioanalyticsInstitute of Biotechnology, Technische Universität BerlinBerlinGermany
| | - Yasushi Hiraoka
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
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17
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Ebrahimi H, Masuda H, Jain D, Cooper JP. Distinct 'safe zones' at the nuclear envelope ensure robust replication of heterochromatic chromosome regions. eLife 2018; 7:32911. [PMID: 29722648 PMCID: PMC5933923 DOI: 10.7554/elife.32911] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 03/30/2018] [Indexed: 12/24/2022] Open
Abstract
Chromosome replication and transcription occur within a complex nuclear milieu whose functional subdomains are beginning to be mapped out. Here we delineate distinct domains of the fission yeast nuclear envelope (NE), focusing on regions enriched for the inner NE protein, Bqt4, or the lamin interacting domain protein, Lem2. Bqt4 is relatively mobile around the NE and acts in two capacities. First, Bqt4 tethers chromosome termini and the mat locus to the NE specifically while these regions are replicating. This positioning is required for accurate heterochromatin replication. Second, Bqt4 mobilizes a subset of Lem2 molecules around the NE to promote pericentric heterochromatin maintenance. Opposing Bqt4-dependent Lem2 mobility are factors that stabilize Lem2 beneath the centrosome, where Lem2 plays a crucial role in kinetochore maintenance. Our data prompt a model in which Bqt4-rich nuclear subdomains are 'safe zones' in which collisions between transcription and replication are averted and heterochromatin is reassembled faithfully.
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Affiliation(s)
- Hani Ebrahimi
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, United States
| | - Hirohisa Masuda
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, United States
| | - Devanshi Jain
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, United States
| | - Julia Promisel Cooper
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, United States
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18
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Aoki K, Niki H. Release of condensin from mitotic chromosomes requires the Ran-GTP gradient in the reorganized nucleus. Biol Open 2017; 6:1614-1628. [PMID: 28954740 PMCID: PMC5703609 DOI: 10.1242/bio.027193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
After mitosis, nuclear reorganization occurs together with decondensation of mitotic chromosomes and reformation of the nuclear envelope, thereby restoring the Ran-GTP gradient between the nucleus and cytoplasm. The Ran-GTP gradient is dependent on Pim1/RCC1. Interestingly, a defect in Pim1/RCC1 in Schizosaccharomyces pombe causes postmitotic condensation of chromatin, namely hypercondensation, suggesting a relationship between the Ran-GTP gradient and chromosome decondensation. However, how Ran-GTP interacts with chromosome decondensation is unresolved. To examine this interaction, we used Schizosaccharomyces japonicus, which is known to undergo partial breakdown of the nuclear membrane during mitosis. We found that Pim1/RCC1 was localized on nuclear pores, but this localization failed in a temperature-sensitive mutant of Pim1/RCC1. The mutant cells exhibited hypercondensed chromatin after mitosis due to prolonged association of condensin on the chromosomes. Conceivably, a condensin-dephosphorylation defect might cause hypercondensed chromatin, since chromosomal localization of condensin is dependent on phosphorylation by cyclin-dependent kinase (CDK). Indeed, CDK-phospho-mimic mutation of condensin alone caused untimely condensin localization, resulting in hypercondensed chromatin. Together, these results suggest that dephosphorylation of CDK sites of condensin might require the Ran-GTP gradient produced by nuclear pore-localized Pim1/RCC1. Summary: A mutant of Pim1/RCC1 caused hypercondensed chromatin after mitosis due to prolonged association of condensin on chromosomes, suggesting that dephosphorylation of CDK sites of condensin might require Ran-GTP after mitosis.
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Affiliation(s)
- Keita Aoki
- Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan .,Department of Genetics, SOKENDAI, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Hironori Niki
- Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, SOKENDAI, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
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19
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Ganguly A, Bhattacharjee C, Bhave M, Kailaje V, Jain BK, Sengupta I, Rangarajan A, Bhattacharyya D. Perturbation of nucleo-cytoplasmic transport affects size of nucleus and nucleolus in human cells. FEBS Lett 2016; 590:631-43. [DOI: 10.1002/1873-3468.12077] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 01/02/2016] [Accepted: 01/18/2016] [Indexed: 01/13/2023]
Affiliation(s)
- Abira Ganguly
- Advanced Centre for Treatment Research & Education in Cancer (ACTREC); Tata Memorial Centre; Navi Mumbai Maharashtra India
| | - Chumki Bhattacharjee
- Advanced Centre for Treatment Research & Education in Cancer (ACTREC); Tata Memorial Centre; Navi Mumbai Maharashtra India
| | - Madhura Bhave
- Advanced Centre for Treatment Research & Education in Cancer (ACTREC); Tata Memorial Centre; Navi Mumbai Maharashtra India
| | - Vaishali Kailaje
- Advanced Centre for Treatment Research & Education in Cancer (ACTREC); Tata Memorial Centre; Navi Mumbai Maharashtra India
| | - Bhawik K. Jain
- Advanced Centre for Treatment Research & Education in Cancer (ACTREC); Tata Memorial Centre; Navi Mumbai Maharashtra India
| | - Isha Sengupta
- Advanced Centre for Treatment Research & Education in Cancer (ACTREC); Tata Memorial Centre; Navi Mumbai Maharashtra India
| | - Annapoorni Rangarajan
- Department of Molecular Reproduction; Development and Genetics; Indian Institute of Science Bangalore; India
| | - Dibyendu Bhattacharyya
- Advanced Centre for Treatment Research & Education in Cancer (ACTREC); Tata Memorial Centre; Navi Mumbai Maharashtra India
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20
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Asakawa H, Yang HJ, Hiraoka Y, Haraguchi T. Virtual Nuclear Envelope Breakdown and Its Regulators in Fission Yeast Meiosis. Front Cell Dev Biol 2016; 4:5. [PMID: 26870731 PMCID: PMC4735346 DOI: 10.3389/fcell.2016.00005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 01/15/2016] [Indexed: 11/24/2022] Open
Abstract
Ran, a small GTPase, is required for the spindle formation and nuclear envelope (NE) formation. After NE breakdown (NEBD) during mitosis in metazoan cells, the Ran-GTP gradient across the NE is lost and Ran-GTP becomes concentrated around chromatin, thus affecting the stability of microtubules and promoting the assembly of spindle microtubules and segregation of chromosomes. Mitosis in which chromosomes are segregated subsequent to NEBD is called “open mitosis.” In contrast, many fungi undergo a process termed “closed mitosis” in which chromosome segregation and spindle formation occur without NEBD. Although the fission yeast Schizosaccharomyces pombe undergoes a closed mitosis, it exhibits a short period during meiosis (anaphase of the second meiosis; called “anaphase II”) when nuclear and cytoplasmic proteins are mixed in the presence of intact NE and nuclear pore complexes (NPC). This “virtual” nuclear envelope breakdown (vNEBD) involves changes in the localization of RanGAP1, an activator of Ran-GTP hydrolysis. Recently, Nup132, a component of the structural core Nup107-160 subcomplex of the NPC, has been shown to be involved in the maintenance of the nuclear cytoplasmic barrier in yeast meiosis. In this review, we highlight the possible roles of RanGAP1 and Nup132 in vNEBD and discuss the biological significance of vNEBD in S. pombe meiosis.
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Affiliation(s)
- Haruhiko Asakawa
- Graduate School of Frontier Biosciences, Osaka University Suita, Japan
| | - Hui-Ju Yang
- Graduate School of Frontier Biosciences, Osaka University Suita, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan; Cell Biology Group, Advanced ICT Research Institute Kobe, National Institute of Information and Communications TechnologyKobe, Japan; Graduate School of Science, Department of Biology, Osaka UniversityToyonaka, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka UniversitySuita, Japan; Cell Biology Group, Advanced ICT Research Institute Kobe, National Institute of Information and Communications TechnologyKobe, Japan; Graduate School of Science, Department of Biology, Osaka UniversityToyonaka, Japan
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21
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Yang HJ, Asakawa H, Haraguchi T, Hiraoka Y. Nup132 modulates meiotic spindle attachment in fission yeast by regulating kinetochore assembly. J Cell Biol 2015; 211:295-308. [PMID: 26483559 PMCID: PMC4621824 DOI: 10.1083/jcb.201501035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 09/11/2015] [Indexed: 02/06/2023] Open
Abstract
The fission yeast nucleoporin Nup132 is required for timely assembly of outer kinetochore proteins during meiotic prophase and its depletion activates the spindle assembly checkpoint in meiosis I, suggesting a role in establishing monopolar spindle attachment through outer kinetochore reorganization at meiotic prophase. During meiosis, the kinetochore undergoes substantial reorganization to establish monopolar spindle attachment. In the fission yeast Schizosaccharomyces pombe, the KNL1–Spc7-Mis12-Nuf2 (KMN) complex, which constitutes the outer kinetochore, is disassembled during meiotic prophase and is reassembled before meiosis I. Here, we show that the nucleoporin Nup132 is required for timely assembly of the KMN proteins: In the absence of Nup132, Mis12 and Spc7 are precociously assembled at the centromeres during meiotic prophase. In contrast, Nuf2 shows timely dissociation and reappearance at the meiotic centromeres. We further demonstrate that depletion of Nup132 activates the spindle assembly checkpoint in meiosis I, possibly because of the increased incidence of erroneous spindle attachment at sister chromatids. These results suggest that precocious assembly of the kinetochores leads to the meiosis I defects observed in the nup132-disrupted mutant. Thus, we propose that Nup132 plays an important role in establishing monopolar spindle attachment at meiosis I through outer kinetochore reorganization at meiotic prophase.
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Affiliation(s)
- Hui-Ju Yang
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Haruhiko Asakawa
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
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22
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Lucena R, Dephoure N, Gygi SP, Kellogg DR, Tallada VA, Daga RR, Jimenez J. Nucleocytoplasmic transport in the midzone membrane domain controls yeast mitotic spindle disassembly. ACTA ACUST UNITED AC 2015; 209:387-402. [PMID: 25963819 PMCID: PMC4427787 DOI: 10.1083/jcb.201412144] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
During anaphase B, Imp1-mediated transport of the AAA-ATPase Cdc48 protein at the membrane domain surrounding the mitotic spindle midzone promotes spindle midzone dissolution in fission yeast. During each cell cycle, the mitotic spindle is efficiently assembled to achieve chromosome segregation and then rapidly disassembled as cells enter cytokinesis. Although much has been learned about assembly, how spindles disassemble at the end of mitosis remains unclear. Here we demonstrate that nucleocytoplasmic transport at the membrane domain surrounding the mitotic spindle midzone, here named the midzone membrane domain (MMD), is essential for spindle disassembly in Schizosaccharomyces pombe cells. We show that, during anaphase B, Imp1-mediated transport of the AAA-ATPase Cdc48 protein at the MMD allows this disassembly factor to localize at the spindle midzone, thereby promoting spindle midzone dissolution. Our findings illustrate how a separate membrane compartment supports spindle disassembly in the closed mitosis of fission yeast.
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Affiliation(s)
- Rafael Lucena
- Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide/Consejo Superior de Investigaciones Cientificas, 41013 Sevilla, Spain Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Noah Dephoure
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Steve P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Victor A Tallada
- Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide/Consejo Superior de Investigaciones Cientificas, 41013 Sevilla, Spain
| | - Rafael R Daga
- Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide/Consejo Superior de Investigaciones Cientificas, 41013 Sevilla, Spain
| | - Juan Jimenez
- Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide/Consejo Superior de Investigaciones Cientificas, 41013 Sevilla, Spain
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23
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Nie M, Boddy MN. Pli1(PIAS1) SUMO ligase protected by the nuclear pore-associated SUMO protease Ulp1SENP1/2. J Biol Chem 2015. [PMID: 26221037 DOI: 10.1074/jbc.m115.673038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Covalent modification of the proteome by SUMO is critical for genetic stability and cell growth. Equally crucial to these processes is the removal of SUMO from its targets by the Ulp1 (HuSENP1/2) family of SUMO proteases. Ulp1 activity is normally spatially restricted, because it is localized to the nuclear periphery via interactions with the nuclear pore. Delocalization of Ulp1 causes DNA damage and cell cycle defects, phenotypes thought to be caused by inappropriate desumoylation of nucleoplasmic targets that are normally spatially protected from Ulp1. Here, we define a novel consequence of Ulp1 deregulation, with a major impact on SUMO pathway function. In fission yeast lacking Nup132 (Sc/HuNUP133), Ulp1 is delocalized and can no longer antagonize sumoylation of the PIAS family SUMO E3 ligase, Pli1. Consequently, SUMO chain-modified Pli1 is targeted for proteasomal degradation by the concerted action of a SUMO-targeted ubiquitin ligase (STUbL) and Cdc48-Ufd1-Npl4. Pli1 degradation causes the profound SUMO pathway defects and associated centromere dysfunction in cells lacking Nup132. Thus, perhaps counterintuitively, Ulp1-mediated desumoylation can promote SUMO modification by stabilizing a SUMO E3 ligase.
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Affiliation(s)
- Minghua Nie
- From the Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Michael N Boddy
- From the Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037
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24
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Asakawa H, Mori C, Ohtsuki C, Iwamoto M, Hiraoka Y, Haraguchi T. Uncleavable Nup98-Nup96 is functional in the fission yeast Schizosaccharomyces pombe. FEBS Open Bio 2015; 5:508-14. [PMID: 26137436 PMCID: PMC4483485 DOI: 10.1016/j.fob.2015.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/18/2015] [Accepted: 06/07/2015] [Indexed: 11/19/2022] Open
Abstract
Essential nucleoporins Nup98 and Nup96 are coded by a single open reading frame, and produced by autopeptidase cleavage. The autocleavage site of Nup98-Nup96 is highly conserved in a wide range of organisms. To understand the importance of autocleavage, we examined a mutant that produces the Nup98-Nup96 joint molecule as a sole protein product of the nup189 (+) gene in the fission yeast Schizosaccharomyces pombe. Cells expressing only the joint molecule were found to be viable. This result indicates that autocleavage of Nup98-Nup96 is dispensable for cell growth, at least under normal culture conditions in S. pombe.
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Affiliation(s)
- Haruhiko Asakawa
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
| | - Chie Mori
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
| | - Chizuru Ohtsuki
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
| | - Masaaki Iwamoto
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
- Corresponding authors at: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan. Tel.: +81 668794620; fax: +81 668794622 (Y. Hiraoka), Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan. Tel.: +81 789692241; fax: +81 789692249 (T. Haraguchi).
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
- Corresponding authors at: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan. Tel.: +81 668794620; fax: +81 668794622 (Y. Hiraoka), Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan. Tel.: +81 789692241; fax: +81 789692249 (T. Haraguchi).
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25
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The kinetochore protein Kis1/Eic1/Mis19 ensures the integrity of mitotic spindles through maintenance of kinetochore factors Mis6/CENP-I and CENP-A. PLoS One 2014; 9:e111905. [PMID: 25375240 PMCID: PMC4222959 DOI: 10.1371/journal.pone.0111905] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/06/2014] [Indexed: 12/14/2022] Open
Abstract
Microtubules play multiple roles in a wide range of cellular phenomena, including cell polarity establishment and chromosome segregation. A number of microtubule regulators have been identified, including microtubule-associated proteins and kinases, and knowledge of these factors has contributed to our molecular understanding of microtubule regulation of each relevant cellular process. The known regulators, however, are insufficient to explain how those processes are linked to one another, underscoring the need to identify additional regulators. To find such novel mechanisms and microtubule regulators, we performed a screen that combined genetics and microscopy for fission yeast mutants defective in microtubule organization. We isolated approximately 900 mutants showing defects in either microtubule organization or the nuclear envelope, and these mutants were classified into 12 categories. We particularly focused on one mutant, kis1, which displayed spindle defects in early mitosis. The kis1 mutant frequently failed to assemble a normal bipolar spindle. The responsible gene encoded a kinetochore protein, Mis19 (also known as Eic1), which localized to the interface of kinetochores and spindle poles. We also found that the inner kinetochore proteins Mis6/CENP-I and Cnp1/CENP-A were delocalized from kinetochores in the kis1 cells and that kinetochore-microtubule attachment was defective. Another mutant, mis6, also displayed similar spindle defects. We conclude that Kis1 is required for inner kinetochore organization, through which Kis1 ensures kinetochore-microtubule attachment and spindle integrity. Thus, we propose an unexpected relationship between inner kinetochore organization and spindle integrity.
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26
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Parry G. Components of the Arabidopsis nuclear pore complex play multiple diverse roles in control of plant growth. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:6057-67. [PMID: 25165147 PMCID: PMC4203139 DOI: 10.1093/jxb/eru346] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The nuclear pore complex (NPC) is a multisubunit protein conglomerate that facilitates movement of RNA and protein between the nucleus and cytoplasm. Relatively little is known regarding the influence of the Arabidopsis NPC on growth and development. Seedling development, flowering time, nuclear morphology, mRNA accumulation, and gene expression changes in Arabidopsis nucleoporin mutants were investigated. Nuclear export of mRNA is differentially affected in plants with defects in nucleoporins that lie in different NPC subcomplexes. This study reveals differences in the manner by which nucleoporins alter molecular and plant growth phenotypes, suggesting that nuclear pore subcomplexes play distinct roles in nuclear transport and reveal a possible feedback relationship between the expression of genes involved in nuclear transport.
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Affiliation(s)
- Geraint Parry
- Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
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27
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Asakawa H, Yang HJ, Yamamoto TG, Ohtsuki C, Chikashige Y, Sakata-Sogawa K, Tokunaga M, Iwamoto M, Hiraoka Y, Haraguchi T. Characterization of nuclear pore complex components in fission yeast Schizosaccharomyces pombe. Nucleus 2014; 5:149-62. [PMID: 24637836 PMCID: PMC4049921 DOI: 10.4161/nucl.28487] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The nuclear pore complex (NPC) is an enormous proteinaceous complex composed of multiple copies of about 30 different proteins called nucleoporins. In this study, we analyzed the composition of the NPC in the model organism Schizosaccharomyces pombe using strains in which individual nucleoporins were tagged with GFP. We identified 31 proteins as nucleoporins by their localization to the nuclear periphery. Gene disruption analysis in previous studies coupled with gene disruption analysis in the present study indicates that 15 of these nucleoporins are essential for vegetative cell growth and the other 16 nucleoporins are non-essential. Among the 16 non-essential nucleoporins, 11 are required for normal progression through meiosis and their disruption caused abnormal spore formation or poor spore viability. Based on fluorescence measurements of GFP-fused nucleoporins, we estimated the composition of the NPC in S. pombe and found that the organization of the S. pombe NPC is largely similar to that of other organisms; a single NPC was estimated as being 45.8–47.8 MDa in size. We also used fluorescence measurements of single NPCs and quantitative western blotting to analyze the composition of the Nup107-Nup160 subcomplex, which plays an indispensable role in NPC organization and function. Our analysis revealed low amounts of Nup107 and Nup131 and high amounts of Nup132 in the Nup107-Nup160 subcomplex, suggesting that the composition of this complex in S. pombe may differ from that in S. cerevisiae and humans. Comparative analysis of NPCs in various organisms will lead to a comprehensive understanding of the functional architecture of the NPC.
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Affiliation(s)
- Haruhiko Asakawa
- Graduate School of Frontier Biosciences; Osaka University; Suita, Japan
| | - Hui-Ju Yang
- Graduate School of Frontier Biosciences; Osaka University; Suita, Japan
| | - Takaharu G Yamamoto
- Advanced ICT Research Institute Kobe; National Institute of Information and Communications Technology; Kobe, Japan
| | - Chizuru Ohtsuki
- Graduate School of Frontier Biosciences; Osaka University; Suita, Japan
| | - Yuji Chikashige
- Advanced ICT Research Institute Kobe; National Institute of Information and Communications Technology; Kobe, Japan; Graduate School of Science; Osaka University; Toyonaka, Japan
| | - Kumiko Sakata-Sogawa
- Department of Biological Information; Graduate School of Bioscience and Biotechnology; Tokyo Institute of Technology; Yokohama, Japan; RIKEN Center for Integrative Medical Sciences (IMS-RCAI); Yokohama, Japan
| | - Makio Tokunaga
- Department of Biological Information; Graduate School of Bioscience and Biotechnology; Tokyo Institute of Technology; Yokohama, Japan; RIKEN Center for Integrative Medical Sciences (IMS-RCAI); Yokohama, Japan
| | - Masaaki Iwamoto
- Advanced ICT Research Institute Kobe; National Institute of Information and Communications Technology; Kobe, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences; Osaka University; Suita, Japan; Advanced ICT Research Institute Kobe; National Institute of Information and Communications Technology; Kobe, Japan; Graduate School of Science; Osaka University; Toyonaka, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences; Osaka University; Suita, Japan; Advanced ICT Research Institute Kobe; National Institute of Information and Communications Technology; Kobe, Japan; Graduate School of Science; Osaka University; Toyonaka, Japan
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28
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Sugiyama T, Wanatabe N, Kitahata E, Tani T, Sugioka-Sugiyama R. Red5 and three nuclear pore components are essential for efficient suppression of specific mRNAs during vegetative growth of fission yeast. Nucleic Acids Res 2013; 41:6674-86. [PMID: 23658229 PMCID: PMC3711435 DOI: 10.1093/nar/gkt363] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Zinc-finger domains are found in many nucleic acid-binding proteins in both prokaryotes and eukaryotes. Proteins carrying zinc-finger domains have important roles in various nuclear transactions, including transcription, mRNA processing and mRNA export; however, for many individual zinc-finger proteins in eukaryotes, the exact function of the protein is not fully understood. Here, we report that Red5 is involved in efficient suppression of specific mRNAs during vegetative growth of Schizosaccharomyces pombe. Red5, which contains five C3H1-type zinc-finger domains, localizes to the nucleus where it forms discrete dots. A red5 point mutation, red5-2, results in the upregulation of specific meiotic mRNAs in vegetative mutant red5-2 cells; northern blot data indicated that these meiotic mRNAs in red5-2 cells have elongated poly(A) tails. RNA-fluorescence in situ hybridization results demonstrate that poly(A)+ RNA species accumulate in the nucleolar regions of red5-deficient cells. Moreover, Red5 genetically interacts with several mRNA export factors. Unexpectedly, three components of the nuclear pore complex also suppress a specific set of meiotic mRNAs. These results indicate that Red5 function is important to meiotic mRNA degradation; they also suggest possible connections among selective mRNA decay, mRNA export and the nuclear pore complex in vegetative fission yeast.
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29
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Bukata L, Parker SL, D'Angelo MA. Nuclear pore complexes in the maintenance of genome integrity. Curr Opin Cell Biol 2013; 25:378-86. [PMID: 23567027 DOI: 10.1016/j.ceb.2013.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/20/2013] [Accepted: 03/13/2013] [Indexed: 11/26/2022]
Abstract
Maintaining genome integrity is crucial for successful organismal propagation and for cell and tissue homeostasis. Several processes contribute to safeguarding the genomic information of cells. These include accurate replication of genetic information, detection and repair of DNA damage, efficient segregation of chromosomes, protection of chromosome ends, and proper organization of genome architecture. Interestingly, recent evidence shows that nuclear pore complexes, the channels connecting the nucleus with the cytoplasm, play important roles in these processes suggesting that these multiprotein platforms are key regulators of genome integrity.
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Affiliation(s)
- Lucas Bukata
- Cardiovascular Research Institute, Biochemistry and Biophysics Department, University of California San Francisco, San Francisco, CA 94158, United States
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30
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González-Aguilera C, Askjaer P. Dissecting the NUP107 complex: multiple components and even more functions. Nucleus 2012; 3:340-8. [PMID: 22713280 DOI: 10.4161/nucl.21135] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Nuclear Pore Complex (NPC) is a fascinating structure whose functional relevance and complexity attract significant interest. Within the NPC, several different subcomplexes interact with each other to form a highly conserved and stable structure. One of these subcomplexes is the NUP107 complex, constituted by 7-9 members. A wide variety of functions have been ascribed to the NUP107 complex, ranging from NPC assembly to mRNA export to cell differentiation. Recently, genetic dissection of the NUP107 complex has provided novel insight to the assembly of the complex and has, moreover, revealed an unexpected connection with the mitotic spindle assembly checkpoint protein MAD1.
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Affiliation(s)
- Cristina González-Aguilera
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Seville, Spain
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31
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Wiermer M, Cheng YT, Imkampe J, Li M, Wang D, Lipka V, Li X. Putative members of the Arabidopsis Nup107-160 nuclear pore sub-complex contribute to pathogen defense. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 70:796-808. [PMID: 22288649 DOI: 10.1111/j.1365-313x.2012.04928.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In eukaryotic cells, transduction of external stimuli into the nucleus to induce transcription and export of mRNAs for translation in the cytoplasm is mediated by nuclear pore complexes (NPCs) composed of nucleoporin proteins (Nups). We previously reported that Arabidopsis MOS3, encoding the homolog of vertebrate Nup96, is required for plant immunity and constitutive resistance mediated by the de-regulated Toll interleukin 1 receptor/nucleotide-binding/leucine-rich repeat (TNL)-type R gene snc1. In vertebrates, Nup96 is a component of the conserved Nup107-160 nuclear pore sub-complex, and implicated in immunity-related mRNA export. Here, we used a reverse genetics approach to examine the requirement for additional subunits of the predicted Arabidopsis Nup107-160 complex in plant immunity. We show that, among eight putative complex members, beside MOS3, only plants with defects in Nup160 or Seh1 are impaired in basal resistance. Constitutive resistance in the snc1 mutant and immunity mediated by TNL-type R genes also depend on functional Nup160 and have a partial requirement for Seh1. Conversely, resistance conferred by coiled coil-type immune receptors operates largely independently of both genes, demonstrating specific contributions to plant defense signaling. Our functional analysis further revealed that defects in nup160 and seh1 result in nuclear accumulation of poly(A) mRNA, and, in the case of nup160, considerable depletion of EDS1, a key positive regulator of basal and TNL-triggered resistance. These findings suggest that Nup160 is required for nuclear mRNA export and full expression of EDS1-conditioned resistance pathways in Arabidopsis.
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MESH Headings
- Active Transport, Cell Nucleus
- Arabidopsis/genetics
- Arabidopsis/immunology
- Arabidopsis/microbiology
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Cytoplasm/genetics
- Cytoplasm/metabolism
- DNA, Plant/genetics
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Disease Resistance
- Gene Expression Regulation, Plant
- Genes, Plant
- Nuclear Pore/genetics
- Nuclear Pore/metabolism
- Nuclear Pore Complex Proteins/genetics
- Nuclear Pore Complex Proteins/metabolism
- Oomycetes/immunology
- Oomycetes/pathogenicity
- Plant Diseases/immunology
- Plant Diseases/microbiology
- Plant Immunity
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/immunology
- Plants, Genetically Modified/metabolism
- Poly A/genetics
- Poly A/metabolism
- RNA Transport
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Reverse Genetics/methods
- Signal Transduction
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Affiliation(s)
- Marcel Wiermer
- Michael Smith Laboratories, Room 301, 2185 East Mall, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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32
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Woolcock KJ, Stunnenberg R, Gaidatzis D, Hotz HR, Emmerth S, Barraud P, Bühler M. RNAi keeps Atf1-bound stress response genes in check at nuclear pores. Genes Dev 2012; 26:683-92. [PMID: 22431512 DOI: 10.1101/gad.186866.112] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
RNAi pathways are prevalent throughout the eukaryotic kingdom and are well known to regulate gene expression on a post-transcriptional level in the cytoplasm. Less is known about possible functions of RNAi in the nucleus. In the fission yeast Schizosaccharomyces pombe, RNAi is crucial to establish and maintain centromeric heterochromatin and functions to repress genome activity by a chromatin silencing mechanism referred to as cotranscriptional gene silencing (CTGS). Mechanistic details and the physiological relevance of CTGS are unknown. Here we show that RNAi components interact with chromatin at nuclear pores to keep stress response genes in check. We demonstrate that RNAi-mediated CTGS represses stress-inducible genes by degrading mRNAs under noninduced conditions. Under chronic heat stress conditions, a Dicer thermoswitch deports Dicer to the cytoplasm, thereby disrupting CTGS and enabling expression of genes implicated in the acquisition of thermotolerance. Taken together, our work highlights a role for nuclear pores and the stress response transcription factor Atf1 in coordinating the interplay between the RNAi machinery and the S. pombe genome and uncovers a novel mode of RNAi regulation in response to an environmental cue.
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Affiliation(s)
- Katrina J Woolcock
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
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33
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Characterization of the ptr5+ gene involved in nuclear mRNA export in fission yeast. Biochem Biophys Res Commun 2012; 418:62-6. [PMID: 22240020 DOI: 10.1016/j.bbrc.2011.12.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 12/26/2011] [Indexed: 11/23/2022]
Abstract
To analyze the mechanisms of mRNA export from the nucleus to the cytoplasm, we have isolated eleven mutants, ptr [poly(A)(+) RNA transport] 1 to 11, which accumulate poly(A)(+) RNA in the nucleus at a nonpermissive temperature in Schizosaccharomyces pombe. Of those, the ptr5-1 mutant shows dots- or a ring-like accumulation of poly(A)(+) RNA at the nuclear periphery after shifting to the nonpermissive temperature. We cloned the ptr5(+) gene and found that it encodes a component of the nuclear pore complex (NPC), nucleoporin 85 (Nup85). The ptr5-1 mutant shows no defects in protein transport, suggesting the specific involvement of Ptr5p/Nup85p in nuclear mRNA export in S. pombe. We identified Seh1p, a nucleoporin interacting with Nup85p, an mRNA-binding protein Mlo3p, and Sac3p, a component of the TREX-2 complex involved in coupling of nuclear mRNA export with transcription, as multi-copy suppressors for the ptr5-1 mutation. In addition, we found that the ptr5-1 mutation is synthetically lethal with a mutation of the mRNA export factor Rae1p, and that the double mutant exaggerates defective nuclear mRNA export, suggesting that Ptr5p/Nup85p is involved in nuclear mRNA export through Rae1p. Interestingly, the ptr5-1 mutation also showed synthetic effects with several prp pre-mRNA splicing mutations, suggesting a functional linkage between the NPCs and the splicing apparatus in the yeast nucleus.
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34
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Tamm T, Grallert A, Grossman EPS, Alvarez-Tabares I, Stevens FE, Hagan IM. Brr6 drives the Schizosaccharomyces pombe spindle pole body nuclear envelope insertion/extrusion cycle. ACTA ACUST UNITED AC 2012; 195:467-84. [PMID: 22042620 PMCID: PMC3206342 DOI: 10.1083/jcb.201106076] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Insertion into and release of the cytoplasmic domain of the Schizosaccharomyces pombe spindle pole body from a nuclear envelope fenestra during mitosis requires Brr6. The fission yeast interphase spindle pole body (SPB) is a bipartite structure in which a bulky cytoplasmic domain is separated from a nuclear component by the nuclear envelope. During mitosis, the SPB is incorporated into a fenestra that forms within the envelope during mitotic commitment. Closure of this fenestra during anaphase B/mitotic exit returns the cytoplasmic component to the cytoplasmic face of an intact interphase nuclear envelope. Here we show that Brr6 is transiently recruited to SPBs at both SPB insertion and extrusion. Brr6 is required for both SPB insertion and nuclear envelope integrity during anaphase B/mitotic exit. Genetic interactions with apq12 and defective sterol assimilation suggest that Brr6 may alter envelope composition at SPBs to promote SPB insertion and extrusion. The restriction of the Brr6 domain to eukaryotes that use a polar fenestra in an otherwise closed mitosis suggests a conserved role in fenestration to enable a single microtubule organizing center to nucleate both cytoplasmic and nuclear microtubules on opposing sides of the nuclear envelope.
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Affiliation(s)
- Tiina Tamm
- Cancer Research UK Cell Division Group, Paterson Institute for Cancer Research, Manchester M20 4BX, England, UK
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35
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Ródenas E, González-Aguilera C, Ayuso C, Askjaer P. Dissection of the NUP107 nuclear pore subcomplex reveals a novel interaction with spindle assembly checkpoint protein MAD1 in Caenorhabditis elegans. Mol Biol Cell 2012; 23:930-44. [PMID: 22238360 PMCID: PMC3290650 DOI: 10.1091/mbc.e11-11-0927] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Nuclear pore complex assembly and kinetochore function depend on the NUP107 subcomplex, but the roles of each of its nine constituents are unknown. NUP107 itself is shown to be dispensable for NPC assembly but needed for proper localization of kinetochore protein NUF2 and Aurora B kinase. Moreover, a novel interaction is found with SAC protein MAD1. Nuclear pore complexes consist of several subcomplexes. The NUP107 complex is important for nucleocytoplasmic transport, nuclear envelope assembly, and kinetochore function. However, the underlying molecular mechanisms and the roles of individual complex members remain elusive. We report the first description of a genetic disruption of NUP107 in a metazoan. Caenorhabditis elegans NUP107/npp-5 mutants display temperature-dependent lethality. Surprisingly, NPP-5 is dispensable for incorporation of most nucleoporins into nuclear pores and for nuclear protein import. In contrast, NPP-5 is essential for proper kinetochore localization of NUP133/NPP-15, another NUP107 complex member, whereas recruitment of NUP96/NPP-10C and ELYS/MEL-28 is NPP-5 independent. We found that kinetochore protein NUF2/HIM-10 and Aurora B/AIR-2 kinase are less abundant on mitotic chromatin upon NPP-5 depletion. npp-5 mutants are hypersensitive to anoxia, suggesting that the spindle assembly checkpoint (SAC) is compromised. Indeed, NPP-5 interacts genetically and physically with SAC protein MAD1/MDF-1, whose nuclear envelope accumulation requires NPP-5. Thus our results strengthen the emerging connection between nuclear pore proteins and chromosome segregation.
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Affiliation(s)
- Eduardo Ródenas
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Seville 41013, Spain
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36
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Abstract
In eukaryotic cells, the spatial segregation of replication and transcription in the nucleus and translation in the cytoplasm imposes the requirement of transporting thousands of macromolecules between these two compartments. Nuclear pore complexes (NPCs) are the sole gateways that facilitate this macromolecular exchange across the nuclear envelope with the help of soluble transport receptors. Whereas the mobile transport machinery is reasonably well understood at the atomic level, a commensurate structural characterization of the NPC has only begun in the past few years. Here, we describe the recent progress toward the elucidation of the atomic structure of the NPC, highlight emerging concepts of its underlying architecture, and discuss key outstanding questions and challenges. The applied structure determination as well as the described design principles of the NPC may serve as paradigms for other macromolecular assemblies.
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Affiliation(s)
- André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
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37
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Yam C, He Y, Zhang D, Chiam KH, Oliferenko S. Divergent Strategies for Controlling the Nuclear Membrane Satisfy Geometric Constraints during Nuclear Division. Curr Biol 2011; 21:1314-9. [DOI: 10.1016/j.cub.2011.06.052] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 05/25/2011] [Accepted: 06/22/2011] [Indexed: 10/17/2022]
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38
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Senger S, Csokmay J, Akbar T, Tanveer A, Jones TI, Sengupta P, Lilly MA. The nucleoporin Seh1 forms a complex with Mio and serves an essential tissue-specific function in Drosophila oogenesis. Development 2011; 138:2133-42. [PMID: 21521741 DOI: 10.1242/dev.057372] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The nuclear pore complex (NPC) mediates the transport of macromolecules between the nucleus and cytoplasm. Recent evidence indicates that structural nucleoporins, the building blocks of the NPC, have a variety of unanticipated cellular functions. Here, we report an unexpected tissue-specific requirement for the structural nucleoporin Seh1 during Drosophila oogenesis. Seh1 is a component of the Nup107-160 complex, the major structural subcomplex of the NPC. We demonstrate that Seh1 associates with the product of the missing oocyte (mio) gene. In Drosophila, mio regulates nuclear architecture and meiotic progression in early ovarian cysts. Like mio, seh1 has a crucial germline function during oogenesis. In both mio and seh1 mutant ovaries, a fraction of oocytes fail to maintain the meiotic cycle and develop as pseudo-nurse cells. Moreover, the accumulation of Mio protein is greatly diminished in the seh1 mutant background. Surprisingly, our characterization of a seh1 null allele indicates that, although required in the female germline, seh1 is dispensable for the development of somatic tissues. Our work represents the first examination of seh1 function within the context of a multicellular organism. In summary, our studies demonstrate that Mio is a novel interacting partner of the conserved nucleoporin Seh1 and add to the growing body of evidence that structural nucleoporins can have novel tissue-specific roles.
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Affiliation(s)
- Stefania Senger
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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39
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Wozniak R, Burke B, Doye V. Nuclear transport and the mitotic apparatus: an evolving relationship. Cell Mol Life Sci 2010; 67:2215-30. [PMID: 20372967 PMCID: PMC11115906 DOI: 10.1007/s00018-010-0325-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Accepted: 02/17/2010] [Indexed: 10/19/2022]
Abstract
The trafficking of macromolecules between the cytoplasm and the nucleus is controlled by the nuclear pore complexes (NPCs) and various transport factors that facilitate the movement of cargos through the NPCs and their accumulation in the target compartment. While their functions in transport are well established, an ever-growing number of observations have also linked components of the nuclear transport machinery to processes that control chromosome segregation during mitosis, including spindle assembly, kinetochore function, and the spindle assembly checkpoint. In this review, we will discuss this evolving area of study and emerging hypotheses that propose key roles for components of the nuclear transport apparatus in mitotic progression.
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Affiliation(s)
- Richard Wozniak
- Department of Cell Biology, University of Alberta, Edmonton, AB, T6G 2H7, Canada.
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40
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Emmerth S, Schober H, Gaidatzis D, Roloff T, Jacobeit K, Bühler M. Nuclear retention of fission yeast dicer is a prerequisite for RNAi-mediated heterochromatin assembly. Dev Cell 2010; 18:102-13. [PMID: 20152181 DOI: 10.1016/j.devcel.2009.11.011] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 10/24/2009] [Accepted: 11/25/2009] [Indexed: 12/20/2022]
Abstract
RNaseIII ribonucleases act at the heart of RNA silencing pathways by processing precursor RNAs into mature microRNAs and siRNAs. In the fission yeast Schizosaccharomyces pombe, siRNAs are generated by the RNaseIII enzyme Dcr1 and are required for heterochromatin formation at centromeres. In this study, we have analyzed the subcellular localization of Dcr1 and found that it accumulates in the nucleus and is enriched at the nuclear periphery. Nuclear accumulation of Dcr1 depends on a short motif that impedes nuclear export promoted by the double-stranded RNA binding domain of Dcr1. Absence of this motif renders Dcr1 mainly cytoplasmic and is accompanied by remarkable changes in gene expression and failure to assemble heterochromatin. Our findings suggest that Dicer proteins are shuttling proteins and that the steady-state subcellular levels can be shifted toward either compartment.
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Affiliation(s)
- Stephan Emmerth
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
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41
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Whittle JRR, Schwartz TU. Architectural nucleoporins Nup157/170 and Nup133 are structurally related and descend from a second ancestral element. J Biol Chem 2009; 284:28442-28452. [PMID: 19674973 PMCID: PMC2788893 DOI: 10.1074/jbc.m109.023580] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 08/03/2009] [Indexed: 11/06/2022] Open
Abstract
The nuclear pore complex (NPC) constitutes one of the largest protein assemblies in the eukaryotic cell and forms the exclusive gateway to the nucleus. The stable, approximately 15-20-MDa scaffold ring of the NPC is built from two multiprotein complexes arranged around a central 8-fold axis. Here we present crystal structures of two large architectural units, yNup170(979-1502) and hNup107(658-925) x hNup133(517-1156), each a constituent of one of the two multiprotein complexes. Conservation of domain arrangement and of tertiary structure suggests that Nup157/170 and Nup133 derived from a common ancestor. Together with the previously established ancestral coatomer element (ACE1), these two elements constitute the major alpha-helical building blocks of the NPC scaffold and define its branched, lattice-like architecture, similar to vesicle coats like COPII. We hypothesize that the extant NPC evolved early during eukaryotic evolution from a rudimentary structure composed of several identical copies of a few ancestral elements, later diversified and specified by gene duplication.
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Affiliation(s)
- James R R Whittle
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Thomas U Schwartz
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
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Structural and functional analysis of Nup120 suggests ring formation of the Nup84 complex. Proc Natl Acad Sci U S A 2009; 106:14281-6. [PMID: 19706512 DOI: 10.1073/pnas.0907453106] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The Nup84 complex constitutes a key building block in the nuclear pore complex (NPC). Here we present the crystal structure of one of its 7 components, Nup120, which reveals a beta propeller and an alpha-helical domain representing a novel fold. We discovered a previously unidentified interaction of Nup120 with Nup133 and confirmed the physiological relevance in vivo. As mapping of the individual components in the Nup84 complex places Nup120 and Nup133 at opposite ends of the heptamer, our findings indicate a head-to-tail arrangement of elongated Nup84 complexes into a ring structure, consistent with a fence-like coat for the nuclear pore membrane. The attachment site for Nup133 lies at the very end of an extended unstructured region, which allows for flexibility in the diameter of the Nup84 complex ring. These results illuminate important roles of terminal unstructured segments in nucleoporins for the architecture, function, and assembly of the NPC.
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Lau CK, Delmar VA, Chan RC, Phung Q, Bernis C, Fichtman B, Rasala BA, Forbes DJ. Transportin regulates major mitotic assembly events: from spindle to nuclear pore assembly. Mol Biol Cell 2009; 20:4043-58. [PMID: 19641022 DOI: 10.1091/mbc.e09-02-0152] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Mitosis in higher eukaryotes is marked by the sequential assembly of two massive structures: the mitotic spindle and the nucleus. Nuclear assembly itself requires the precise formation of both nuclear membranes and nuclear pore complexes. Previously, importin alpha/beta and RanGTP were shown to act as dueling regulators to ensure that these assembly processes occur only in the vicinity of the mitotic chromosomes. We now find that the distantly related karyopherin, transportin, negatively regulates nuclear envelope fusion and nuclear pore assembly in Xenopus egg extracts. We show that transportin-and importin beta-initiate their regulation as early as the first known step of nuclear pore assembly: recruitment of the critical pore-targeting nucleoporin ELYS/MEL-28 to chromatin. Indeed, each karyopherin can interact directly with ELYS. We further define the nucleoporin subunit targets for transportin and importin beta and find them to be largely the same: ELYS, the Nup107/160 complex, Nup53, and the FG nucleoporins. Equally importantly, we find that transportin negatively regulates mitotic spindle assembly. These negative regulatory events are counteracted by RanGTP. We conclude that the interplay of the two negative regulators, transportin and importin beta, along with the positive regulator RanGTP, allows precise choreography of multiple cell cycle assembly events.
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Affiliation(s)
- Corine K Lau
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0347, USA
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Debler EW, Ma Y, Seo HS, Hsia KC, Noriega TR, Blobel G, Hoelz A. A fence-like coat for the nuclear pore membrane. Mol Cell 2009; 32:815-26. [PMID: 19111661 DOI: 10.1016/j.molcel.2008.12.001] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 11/21/2008] [Accepted: 12/02/2008] [Indexed: 01/11/2023]
Abstract
We recently proposed a cylindrical coat for the nuclear pore membrane in the nuclear pore complex (NPC). This scaffold is generated by multiple copies of seven nucleoporins. Here, we report three crystal structures of the nucleoporin pair Seh1*Nup85, which is part of the coat cylinder. The Seh1*Nup85 assembly bears resemblance in its shape and dimensions to that of another nucleoporin pair, Sec13*Nup145C. Furthermore, the Seh1*Nup85 structures reveal a hinge motion that may facilitate conformational changes in the NPC during import of integral membrane proteins and/or during nucleocytoplasmic transport. We propose that Seh1*Nup85 and Sec13*Nup145C form 16 alternating, vertical rods that are horizontally linked by the three remaining nucleoporins of the coat cylinder. Shared architectural and mechanistic principles with the COPII coat indicate a common evolutionary origin and support the notion that the NPC coat represents another class of membrane coats.
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Affiliation(s)
- Erik W Debler
- Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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45
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Liu HL, De Souza CPC, Osmani AH, Osmani SA. The three fungal transmembrane nuclear pore complex proteins of Aspergillus nidulans are dispensable in the presence of an intact An-Nup84-120 complex. Mol Biol Cell 2008; 20:616-30. [PMID: 19019988 DOI: 10.1091/mbc.e08-06-0628] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In Aspergillus nidulans nuclear pore complexes (NPCs) undergo partial mitotic disassembly such that 12 NPC proteins (Nups) form a core structure anchored across the nuclear envelope (NE). To investigate how the NPC core is maintained, we affinity purified the major core An-Nup84-120 complex and identified two new fungal Nups, An-Nup37 and An-ELYS, previously thought to be vertebrate specific. During mitosis the An-Nup84-120 complex locates to the NE and spindle pole bodies but, unlike vertebrate cells, does not concentrate at kinetochores. We find that mutants lacking individual An-Nup84-120 components are sensitive to the membrane destabilizer benzyl alcohol (BA) and high temperature. Although such mutants display no defects in mitotic spindle formation, they undergo mitotic specific disassembly of the NPC core and transient aggregation of the mitotic NE, suggesting the An-Nup84-120 complex might function with membrane. Supporting this, we show cells devoid of all known fungal transmembrane Nups (An-Ndc1, An-Pom152, and An-Pom34) are viable but that An-ndc1 deletion combined with deletion of individual An-Nup84-120 components is either lethal or causes sensitivity to treatments expected to destabilize membrane. Therefore, the An-Nup84-120 complex performs roles, perhaps at the NPC membrane as proposed previously, that become essential without the An-Ndc1 transmembrane Nup.
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Affiliation(s)
- Hui-Lin Liu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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46
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D'Angelo MA, Hetzer MW. Structure, dynamics and function of nuclear pore complexes. Trends Cell Biol 2008; 18:456-66. [PMID: 18786826 DOI: 10.1016/j.tcb.2008.07.009] [Citation(s) in RCA: 281] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 07/21/2008] [Accepted: 07/22/2008] [Indexed: 12/15/2022]
Abstract
Nuclear pore complexes are large aqueous channels that penetrate the nuclear envelope, thereby connecting the nuclear interior with the cytoplasm. Until recently, these macromolecular complexes were viewed as static structures, the only function of which was to control the molecular trafficking between the two compartments. It has now become evident that this simplistic scenario is inaccurate and that nuclear pore complexes are highly dynamic multiprotein assemblies involved in diverse cellular processes ranging from the organization of the cytoskeleton to gene expression. In this review, we discuss the most recent developments in the nuclear-pore-complex field, focusing on the assembly, disassembly, maintenance and function of this macromolecular structure.
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Affiliation(s)
- Maximiliano A D'Angelo
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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47
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Lupu F, Alves A, Anderson K, Doye V, Lacy E. Nuclear pore composition regulates neural stem/progenitor cell differentiation in the mouse embryo. Dev Cell 2008; 14:831-42. [PMID: 18539113 DOI: 10.1016/j.devcel.2008.03.011] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 10/25/2007] [Accepted: 03/19/2008] [Indexed: 01/06/2023]
Abstract
Serving as the primary conduit for communication between the nucleus and the cytoplasm, nuclear pore complexes (NPCs) impact nearly every cellular process. The extent to which NPC composition varies and the functional significance of such variation in mammalian development has not been investigated. Here we report that a null allele of mouse nucleoporin Nup133, a structural subunit of the NPC, disrupts neural differentiation. We find that expression of Nup133 is cell type and developmental stage restricted, with prominent expression in dividing progenitors. Nup133-deficient epiblast and ES cells abnormally maintain features of pluripotency and differentiate inefficiently along the neural lineage. Neural progenitors achieve correct spatial patterning in mutant embryos; however, they are impaired in generating terminally differentiated neurons, as are Nup133 null ES cells. Our results reveal a role for structural nucleoporins in coordinating cell differentiation events in the developing embryo.
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Affiliation(s)
- Floria Lupu
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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Katsani KR, Karess RE, Dostatni N, Doye V. In vivo dynamics of Drosophila nuclear envelope components. Mol Biol Cell 2008; 19:3652-66. [PMID: 18562695 DOI: 10.1091/mbc.e07-11-1162] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Nuclear pore complexes (NPCs) are multisubunit protein entities embedded into the nuclear envelope (NE). Here, we examine the in vivo dynamics of the essential Drosophila nucleoporin Nup107 and several other NE-associated proteins during NE and NPCs disassembly and reassembly that take place within each mitosis. During both the rapid mitosis of syncytial embryos and the more conventional mitosis of larval neuroblasts, Nup107 is gradually released from the NE, but it remains partially confined to the nuclear (spindle) region up to late prometaphase, in contrast to nucleoporins detected by wheat germ agglutinin and lamins. We provide evidence that in all Drosophila cells, a structure derived from the NE persists throughout metaphase and early anaphase. Finally, we examined the dynamics of the spindle checkpoint proteins Mad2 and Mad1. During mitotic exit, Mad2 and Mad1 are actively imported back from the cytoplasm into the nucleus after the NE and NPCs have reformed, but they reassociate with the NE only later in G1, concomitantly with the recruitment of the basket nucleoporin Mtor (the Drosophila orthologue of vertebrate Tpr). Surprisingly, Drosophila Nup107 shows no evidence of localization to kinetochores, despite the demonstrated importance of this association in mammalian cells.
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Hsia KC, Stavropoulos P, Blobel G, Hoelz A. Architecture of a coat for the nuclear pore membrane. Cell 2008; 131:1313-26. [PMID: 18160040 PMCID: PMC2213454 DOI: 10.1016/j.cell.2007.11.038] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 10/26/2007] [Accepted: 11/29/2007] [Indexed: 01/06/2023]
Abstract
The symmetric core of the nuclear pore complex can be considered schematically as a series of concentric cylinders. A peripheral cylinder coating the pore membrane contains the previously characterized, elongated heptamer that harbors Sec13-Nup145C in its middle section. Strikingly, Sec13-Nup145C crystallizes as a hetero-octamer in two space groups. Oligomerization of Sec13-Nup145C was confirmed biochemically. Importantly, the numerous interacting surfaces in the hetero-octamer are evolutionarily highly conserved, further underlining the physiological relevance of the oligomerization. The hetero-octamer forms a slightly curved, yet rigid rod of sufficient length to span the entire height of the proposed membrane-adjacent cylinder. In concordance with the dimensions and symmetry of the nuclear pore complex core, we suggest that the cylinder is constructed of four antiparallel rings, each ring being composed of eight heptamers arranged in a head-to-tail fashion. Our model proposes that the hetero-octamer would vertically traverse and connect the four stacked rings.
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Affiliation(s)
- Kuo-Chiang Hsia
- Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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50
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Theisen U, Straube A, Steinberg G. Dynamic rearrangement of nucleoporins during fungal "open" mitosis. Mol Biol Cell 2008; 19:1230-40. [PMID: 18172026 DOI: 10.1091/mbc.e07-02-0130] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mitosis in animals starts with the disassembly of the nuclear pore complexes and the breakdown of the nuclear envelope. In contrast to many fungi, the corn smut fungus Ustilago maydis also removes the nuclear envelope. Here, we report on the dynamic behavior of the nucleoporins Nup214, Pom152, Nup133, and Nup107 in this "open" fungal mitosis. In prophase, the nuclear pore complexes disassembled and Nup214 and Pom152 dispersed in the cytoplasm and in the endoplasmic reticulum, respectively. Nup107 and Nup133 initially spread throughout the cytoplasm, but in metaphase and early anaphase occurred on the chromosomes. In anaphase, the Nup107-subcomplex redistributed to the edge of the chromosome masses, where the new envelope was reconstituted. Subsequently, Nup214 and Pom152 are recruited to the nuclear pores and protein import starts. Recruitment of nucleoporins and protein import reached a steady state in G2 phase. Formation of the nuclear envelope and assembly of nuclear pores occurred in the absence of microtubules or F-actin, but not if both were disrupted. Thus, the basic principles of nuclear pore complex dynamics seem to be conserved in organisms displaying open mitosis.
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Affiliation(s)
- Ulrike Theisen
- Max-Planck-Institut für terrestrische Mikrobiologie, D-35043 Marburg, Germany
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