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Bannoura SF, Khan HY, Uddin MH, Mohammad RM, Pasche BC, Azmi AS. Targeting guanine nucleotide exchange factors for novel cancer drug discovery. Expert Opin Drug Discov 2024; 19:949-959. [PMID: 38884380 DOI: 10.1080/17460441.2024.2368242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 06/10/2024] [Indexed: 06/18/2024]
Abstract
INTRODUCTION Guanine nucleotide exchange factors (GEFs) regulate the activation of small GTPases (G proteins) of the Ras superfamily proteins controlling cellular functions. Ras superfamily proteins act as 'molecular switches' that are turned 'ON' by guanine exchange. There are five major groups of Ras family GTPases: Ras, Ran, Rho, Rab and Arf, with a variety of different GEFs regulating their GTP loading. GEFs have been implicated in various diseases including cancer. This makes GEFs attractive targets to modulate signaling networks controlled by small GTPases. AREAS COVERED In this review, the roles and mechanisms of GEFs in malignancy are outlined. The mechanism of guanine exchange activity by GEFs on a small GTPase is illustrated. Then, some examples of GEFs that are significant in cancer are presented with a discussion on recent progress in therapeutic targeting efforts using a variety of approaches. EXPERT OPINION Recently, GEFs have emerged as potential therapeutic targets for novel cancer drug development. Targeting small GTPases is challenging; thus, targeting their activation by GEFs is a promising strategy. Most GEF-targeted drugs are still in preclinical development. A deeper biological understanding of the underlying mechanisms of GEF activity and utilizing advanced technology are necessary to enhance drug discovery for GEFs in cancer.
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Affiliation(s)
- Sahar F Bannoura
- Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Husain Yar Khan
- Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Md Hafiz Uddin
- Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Ramzi M Mohammad
- Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Boris C Pasche
- Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Asfar S Azmi
- Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USA
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2
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Huang SK, Rubinstein JL, Kay LE. Cryo-EM of the Nucleosome Core Particle Bound to Ran-RCC1 Reveals a Dynamic Complex. Biochemistry 2024; 63:880-892. [PMID: 38501608 DOI: 10.1021/acs.biochem.3c00724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Ras-related nuclear protein (Ran) is a member of the Ras superfamily of small guanosine triphosphatases (GTPases) and a regulator of multiple cellular processes. In healthy cells, the GTP-bound form of Ran is concentrated at chromatin, creating a Ran•GTP gradient that provides the driving force for nucleocytoplasmic transport, mitotic spindle assembly, and nuclear envelope formation. The Ran•GTP gradient is maintained by the regulator of chromatin condensation 1 (RCC1), a guanine nucleotide exchange factor that accelerates GDP/GTP exchange in Ran. RCC1 interacts with nucleosomes, which are the fundamental repeating units of eukaryotic chromatin. Here, we present a cryo-EM analysis of a trimeric complex composed of the nucleosome core particle (NCP), RCC1, and Ran. While the contacts between RCC1 and Ran in the complex are preserved compared with a previously determined structure of RCC1-Ran, our study reveals that RCC1 and Ran interact dynamically with the NCP and undergo rocking motions on the nucleosome surface. Furthermore, the switch 1 region of Ran, which plays an important role in mediating conformational changes associated with the substitution of GDP and GTP nucleotides in Ras family members, appears to undergo disorder-order transitions and forms transient contacts with the C-terminal helix of histone H2B. Nucleotide exchange assays performed in the presence and absence of NCPs are not consistent with an active role for nucleosomes in nucleotide exchange, at least in vitro. Instead, the nucleosome stabilizes RCC1 and serves as a hub that concentrates RCC1 and Ran to promote efficient Ran•GDP to Ran•GTP conversion.
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Affiliation(s)
- Shuya Kate Huang
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Chemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Hospital for Sick Children, Program in Molecular Medicine, Toronto, ON M5G 1X8, Canada
| | - John L Rubinstein
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Hospital for Sick Children, Program in Molecular Medicine, Toronto, ON M5G 1X8, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Lewis E Kay
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Chemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Hospital for Sick Children, Program in Molecular Medicine, Toronto, ON M5G 1X8, Canada
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El-Tanani M, Nsairat H, Mishra V, Mishra Y, Aljabali AAA, Serrano-Aroca Á, Tambuwala MM. Ran GTPase and Its Importance in Cellular Signaling and Malignant Phenotype. Int J Mol Sci 2023; 24:ijms24043065. [PMID: 36834476 PMCID: PMC9968026 DOI: 10.3390/ijms24043065] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 02/08/2023] Open
Abstract
Ran is a member of the Ras superfamily of proteins, which primarily regulates nucleocytoplasmic trafficking and mediates mitosis by regulating spindle formation and nuclear envelope (NE) reassembly. Therefore, Ran is an integral cell fate determinant. It has been demonstrated that aberrant Ran expression in cancer is a result of upstream dysregulation of the expression of various factors, such as osteopontin (OPN), and aberrant activation of various signaling pathways, including the extracellular-regulated kinase/mitogen-activated protein kinase (ERK/MEK) and phosphatidylinositol 3-kinase/Protein kinase B (PI3K/Akt) pathways. In vitro, Ran overexpression has severe effects on the cell phenotype, altering proliferation, adhesion, colony density, and invasion. Therefore, Ran overexpression has been identified in numerous types of cancer and has been shown to correlate with tumor grade and the degree of metastasis present in various cancers. The increased malignancy and invasiveness have been attributed to multiple mechanisms. Increased dependence on Ran for spindle formation and mitosis is a consequence of the upregulation of these pathways and the ensuing overexpression of Ran, which increases cellular dependence on Ran for survival. This increases the sensitivity of cells to changes in Ran concentration, with ablation being associated with aneuploidy, cell cycle arrest, and ultimately, cell death. It has also been demonstrated that Ran dysregulation influences nucleocytoplasmic transport, leading to transcription factor misallocation. Consequently, patients with tumors that overexpress Ran have been shown to have a higher malignancy rate and a shorter survival time compared to their counterparts.
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Affiliation(s)
- Mohamed El-Tanani
- Pharmacological and Diagnostic Research Centre, Faculty of Pharmacy, Al-Ahliyya Amman University, Amman 19328, Jordan
- Correspondence:
| | - Hamdi Nsairat
- Pharmacological and Diagnostic Research Centre, Faculty of Pharmacy, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - Vijay Mishra
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, India
| | - Yachana Mishra
- Department of Zoology, School of Bioengineering and Biosciences, Lovely Professional University, Phagwara 144411, India
| | - Alaa A. A. Aljabali
- Department of Pharmaceutics & Pharmaceutical Technology, Yarmouk University, Irbid 21163, Jordan
| | - Ángel Serrano-Aroca
- Biomaterials and Bioengineering Laboratory, Centro de Investigación Traslacional San Alberto Magno, Universidad Católica de Valencia San Vicente Mártir, c/Guillem de Castro 94, 46001 Valencia, Spain
| | - Murtaza M. Tambuwala
- Lincoln Medical School, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, UK
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4
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Luo D, Liu J, Wu Y, Zhang X, Zhou Q, Fang L, Liu Z. NUCLEAR TRANSPORT FACTOR 2-LIKE improves drought tolerance by modulating leaf water loss in alfalfa (Medicago sativa L.). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 112:429-450. [PMID: 36006043 DOI: 10.1111/tpj.15955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 07/14/2022] [Accepted: 08/18/2022] [Indexed: 06/15/2023]
Abstract
Drought is a major environmental factor that limits the production of alfalfa (Medicago sativa). In the present study, M. sativa NUCLEAR TRANSPORT FACTOR 2-LIKE (MsNTF2L) was identified as a nucleus-, cytoplasm-, and plasma membrane-localized protein. Its transcriptional expression was highly induced by ABA and drought stress. Overexpression of MsNTF2L in Arabidopsis resulted in hypersensitivity to ABA during both the seed germination and seedling growth stages. However, transgenic Arabidopsis plants exhibited enhanced tolerance to drought stress by reducing the levels of reactive oxygen species (ROS) and increasing the expression of stress/ABA-inducible genes. Consistently, analysis of MsNTF2L overexpression (OE) and RNA interference (RNAi) alfalfa plants revealed that MsNTF2L confers drought tolerance through promoting ROS scavenging, a decrease in stomatal density, ABA-induced stomatal closure, and epicuticular wax crystal accumulation. MsNTF2L highly affected epicuticular wax deposition, as a large group of wax biosynthesis and transport genes were influenced in the alfalfa OE and RNAi lines. Furthermore, transcript profiling of drought-treated alfalfa WT, OE, and RNAi plants showed a differential drought response for genes related to stress/ABA signaling, antioxidant defense, and photosynthesis. Taken together, these results reveal that MsNTF2L confers drought tolerance in alfalfa via modulation of leaf water loss (by regulating both stomata and wax deposition), antioxidant defense, and photosynthesis.
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Affiliation(s)
- Dong Luo
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
- Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Jie Liu
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
| | - Yuguo Wu
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
| | - Xi Zhang
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
| | - Qiang Zhou
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
| | - Longfa Fang
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
| | - Zhipeng Liu
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Research Center of Grassland Industry, Ministry of Education, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China
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5
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Fine-tuning cell organelle dynamics during mitosis by small GTPases. Front Med 2022; 16:339-357. [PMID: 35759087 DOI: 10.1007/s11684-022-0926-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/24/2022] [Indexed: 11/04/2022]
Abstract
During mitosis, the allocation of genetic material concurs with organelle transformation and distribution. The coordination of genetic material inheritance with organelle dynamics directs accurate mitotic progression, cell fate determination, and organismal homeostasis. Small GTPases belonging to the Ras superfamily regulate various cell organelles during division. Being the key regulators of membrane dynamics, the dysregulation of small GTPases is widely associated with cell organelle disruption in neoplastic and non-neoplastic diseases, such as cancer and Alzheimer's disease. Recent discoveries shed light on the molecular properties of small GTPases as sophisticated modulators of a remarkably complex and perfect adaptors for rapid structure reformation. This review collects current knowledge on small GTPases in the regulation of cell organelles during mitosis and highlights the mediator role of small GTPase in transducing cell cycle signaling to organelle dynamics during mitosis.
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6
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Qin Z, Wu YN, Sun TT, Ma T, Xu M, Pang C, Li SW, Li S. Arabidopsis RAN GTPases are critical for mitosis during male and female gametogenesis. FEBS Lett 2022; 596:1892-1903. [PMID: 35680649 DOI: 10.1002/1873-3468.14422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/30/2022] [Accepted: 05/31/2022] [Indexed: 11/09/2022]
Abstract
The development of male and female gametophytes is a prerequisite for successful propagation of angiosperms. The small GTPases RAN play fundamental roles in numerous cellular processes. Although RAN GTPases have been characterized in plants, their roles in cellular processes are far from understood. We report here that RAN GTPases in Arabidopsis are critical for gametophytic development. RAN1 loss-of-function showed no defects in gametophytic development likely due to redundancy. However, the expression of a dominant negative or constitutively active RAN1 resulted in gametophytic lethality. Genetic interference of RAN GTPases caused the arrest of pollen mitosis I and of mitosis of functional megaspores, implying a key role of properly regulated RAN activity in mitosis during gametophytic development.
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Affiliation(s)
- Zheng Qin
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tian'jin, China
| | - Ya-Nan Wu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Tian-Tian Sun
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Ting Ma
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Meng Xu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Chen Pang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Shan-Wei Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Sha Li
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tian'jin, China.,State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
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7
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Holzer G, Antonin W. Nup50 plays more than one instrument. Cell Cycle 2022; 21:1785-1794. [PMID: 35549614 PMCID: PMC9359400 DOI: 10.1080/15384101.2022.2074742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Nup50 is nuclear pore complex component localized to the nuclear side of the pore and in the nucleoplasm. It has been characterized as an auxiliary factor in nuclear transport reactions. Our recent work indicates that it interacts with and stimulates RCC1, the sole guanine nucleotide exchange factor for the GTPase Ran. Here, we discuss how this interaction might contribute to Nup50 function in nuclear transport but also its other functions like control of gene expression, cell cycle and DNA damage repair.
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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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8
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The Nuclear Pore Complex: Birth, Life, and Death of a Cellular Behemoth. Cells 2022; 11:cells11091456. [PMID: 35563762 PMCID: PMC9100368 DOI: 10.3390/cells11091456] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/22/2022] [Accepted: 04/23/2022] [Indexed: 02/01/2023] Open
Abstract
Nuclear pore complexes (NPCs) are the only transport channels that cross the nuclear envelope. Constructed from ~500–1000 nucleoporin proteins each, they are among the largest macromolecular assemblies in eukaryotic cells. Thanks to advances in structural analysis approaches, the construction principles and architecture of the NPC have recently been revealed at submolecular resolution. Although the overall structure and inventory of nucleoporins are conserved, NPCs exhibit significant compositional and functional plasticity even within single cells and surprising variability in their assembly pathways. Once assembled, NPCs remain seemingly unexchangeable in post-mitotic cells. There are a number of as yet unresolved questions about how the versatility of NPC assembly and composition is established, how cells monitor the functional state of NPCs or how they could be renewed. Here, we review current progress in our understanding of the key aspects of NPC architecture and lifecycle.
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9
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The intricate roles of RCC1 in normal cells and cancer cells. Biochem Soc Trans 2022; 50:83-93. [PMID: 35191966 DOI: 10.1042/bst20210861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/24/2022] [Accepted: 02/02/2022] [Indexed: 11/17/2022]
Abstract
RCC1 (regulator of chromosome condensation 1) is a highly conserved chromatin-binding protein and the only known guanine-nucleotide exchange factor of Ran (a nuclear Ras homolog). RCC1 plays an essential role in the regulation of cell cycle-related activities such as nuclear envelope formation, nuclear pore complex and spindle assembly, and nucleocytoplasmic transport. Over the last decade, increasing evidence has emerged highlighting the potential relevance of RCC1 to carcinogenesis, especially cervical, lung, and breast cancer. In this review, we briefly discuss the roles of RCC1 in both normal and tumor cells based on articles published in recent years, followed by a brief overview of future perspectives in the field.
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Holzer G, Antonin W. Nuclear Pore Complex Assembly Using Xenopus Egg Extract. Methods Mol Biol 2022; 2502:51-66. [PMID: 35412230 DOI: 10.1007/978-1-0716-2337-4_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Xenopus egg extract is a powerful tool for the in vitro investigation of complex cellular mechanisms. Here we describe how to obtain and employ interphase Xenopus egg extract to study nuclear pore complex assembly and how to analyze the process using Western blot or immunofluorescence based assays. The function of proteins can be conveniently assayed by high-efficient antibody mediated depletion.
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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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11
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Tamura K, Ueda H, Hara-Nishimura I. In vitro assembly of nuclear envelope in tobacco cultured cells. Nucleus 2021; 12:82-89. [PMID: 34030583 PMCID: PMC8158034 DOI: 10.1080/19491034.2021.1930681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 11/17/2022] Open
Abstract
The coordinated regulation of the nucelar envelope (NE) reassembly during cell division is an essential event. However, there is little information on the molecular components involved in NE assembly in plant cells. Here we developed an in vitro assay of NE assembly using tobacco BY-2 cultured cells. To start the NE assembly reaction, the demembranated nuclei and the S12 fraction (cytosol and microsomes) were mixed in the presence of GTP and ATP nucleotides. Time-course analysis indicated that tubule structures were extended from the microsomal vesicles that accumulated on the demembranated nuclei, and finally sealed the NE. Immunofluorescence confirmed that the assembled membrane contains a component of nuclear pore complex. The efficiency of the NE assembly is significantly inhibited by GTPγS that suppresses membrane fusion. This in-vitro assay system may elucidate the role of specific proteins and provide important insights into the molecular machinery of NE assembly in plant cells.
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Affiliation(s)
- Kentaro Tamura
- Department of Environmental and Life Sciences, School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan
| | - Haruko Ueda
- Faculty of Science and Engineering, Konan University, Kobe, Japan
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12
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Bayat Z, Farhadi Z, Taherkhani A. Identification of potential biomarkers associated with poor prognosis in oral squamous cell carcinoma through integrated bioinformatics analysis: A pilot study. GENE REPORTS 2021. [DOI: 10.1016/j.genrep.2021.101243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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13
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Nord MS, Bernis C, Carmona S, Garland DC, Travesa A, Forbes DJ. Exportins can inhibit major mitotic assembly events in vitro: membrane fusion, nuclear pore formation, and spindle assembly. Nucleus 2021; 11:178-193. [PMID: 32762441 PMCID: PMC7540616 DOI: 10.1080/19491034.2020.1798093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Xenopus egg extracts are a powerful in vitro tool for studying complex biological processes, including nuclear reconstitution, nuclear membrane and pore assembly, and spindle assembly. Extracts have been further used to demonstrate a moonlighting regulatory role for nuclear import receptors or importins on these cell cycle assembly events. Here we show that exportins can also play a role in these events. Addition of Crm1, Exportin-t, or Exportin-5 decreased nuclear pore assembly in vitro. RanQ69L-GTP, a constitutively active form of RanGTP, ameliorated inhibition. Both Crm1 and Exportin-t inhibited fusion of nuclear membranes, again counteracted by RanQ69L-GTP. In mitotic extracts, Crm1 and Exportin-t negatively impacted spindle assembly. Pulldowns from the extracts using Crm1- or Exportin-t-beads revealed nucleoporins known to be essential for both nuclear pore and spindle assembly, with RanQ69L-GTP decreasing a subset of these target interactions. This study suggests a model where exportins, like importins, can regulate major mitotic assembly events.
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Affiliation(s)
- Matthew S Nord
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Cyril Bernis
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Sarah Carmona
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Dennis C Garland
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Anna Travesa
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Douglass J Forbes
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
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14
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Lee J, Park J, Kim JH, Lee G, Park TE, Yoon KJ, Kim YK, Lim C. LSM12-EPAC1 defines a neuroprotective pathway that sustains the nucleocytoplasmic RAN gradient. PLoS Biol 2020; 18:e3001002. [PMID: 33362237 PMCID: PMC7757817 DOI: 10.1371/journal.pbio.3001002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 11/19/2020] [Indexed: 02/07/2023] Open
Abstract
Nucleocytoplasmic transport (NCT) defects have been implicated in neurodegenerative diseases such as C9ORF72-associated amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). Here, we identify a neuroprotective pathway of like-Sm protein 12 (LSM12) and exchange protein directly activated by cyclic AMP 1 (EPAC1) that sustains the nucleocytoplasmic RAN gradient and thereby suppresses NCT dysfunction by the C9ORF72-derived poly(glycine-arginine) protein. LSM12 depletion in human neuroblastoma cells aggravated poly(GR)-induced impairment of NCT and nuclear integrity while promoting the nuclear accumulation of poly(GR) granules. In fact, LSM12 posttranscriptionally up-regulated EPAC1 expression, whereas EPAC1 overexpression rescued the RAN gradient and NCT defects in LSM12-deleted cells. C9-ALS patient-derived neurons differentiated from induced pluripotent stem cells (C9-ALS iPSNs) displayed low expression of LSM12 and EPAC1. Lentiviral overexpression of LSM12 or EPAC1 indeed restored the RAN gradient, mitigated the pathogenic mislocalization of TDP-43, and suppressed caspase-3 activation for apoptosis in C9-ALS iPSNs. EPAC1 depletion biochemically dissociated RAN-importin β1 from the cytoplasmic nuclear pore complex, thereby dissipating the nucleocytoplasmic RAN gradient essential for NCT. These findings define the LSM12-EPAC1 pathway as an important suppressor of the NCT-related pathologies in C9-ALS/FTD. A post-transcriptional circuit comprising LSM12 and EPAC1 suppresses neurodegenerative pathologies in C9ORF72-associated amyotrophic lateral sclerosis by establishing the RAN gradient and sustaining nucleocytoplasmic transport.
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Affiliation(s)
- Jongbo Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Jumin Park
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Ji-hyung Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Giwook Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Tae-Eun Park
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Ki-Jun Yoon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Yoon Ki Kim
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul, Republic of Korea
- Division of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Chunghun Lim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- * E-mail:
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15
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Transcriptome Analysis Reveals the Negative Effect of 16 T High Static Magnetic Field on Osteoclastogenesis of RAW264.7 Cells. BIOMED RESEARCH INTERNATIONAL 2020; 2020:5762932. [PMID: 32309435 PMCID: PMC7140147 DOI: 10.1155/2020/5762932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/03/2020] [Indexed: 01/05/2023]
Abstract
The magnetic field is the most common element in the universe, and high static magnetic field (HiSMF) has been reported to act as an inhibited factor for osteoclasts differentiation. Although many studies have indicated the negative role of HiSMF on osteoclastogenesis of RANKL-induced RAW264.7 cells, the molecular mechanism is still elusive. In this study, the HiSMF-retarded cycle and weakened differentiation of RAW264.7 cells was identified. Through RNA-seq analysis, RANKL-induced RAW264.7 cells under HiSMF were analysed, and a total number of 197 differentially expressed genes (DEGs) were discovered. Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that regulators of cell cycle and cell division such as Bub1b, Rbl1, Ube2c, Kif11, and Nusap1 were highly expressed, and CtsK, the marker gene of osteoclastogenesis was downregulated in HiSMF group. In addition, pathways related to DNA replication, cell cycle, and metabolic pathways were significantly inhibited in the HiSMF group compared to the Control group. Collectively, this study describes the negative changes occurring throughout osteoclastogenesis under 16 T HiSMF treatment from the morphological and molecular perspectives. Our study provides information that may be utilized in improving magnetotherapy on bone disease.
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16
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Zhang C, Zhao X, Du W, Shen J, Li S, Li Z, Wang Z, Liu F. Ran promotes the proliferation and migration ability of head and neck squamous cell carcinoma cells. Pathol Res Pract 2020; 216:152951. [PMID: 32334891 DOI: 10.1016/j.prp.2020.152951] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/15/2020] [Accepted: 03/29/2020] [Indexed: 11/17/2022]
Abstract
HNSCC is an aggressive tumor that often recurrence and metastasis. Although the treatment of HNSCC has improved over the past few decades, it is easy to recurrence even after comprehensive treatment. Ran is a small Ras-related GTPase belonging to the Ras superfamily. Recently, Ran has been proven to be an important oncogene involved in the metastatic progression of many human cancers. But there is seldom research on HNSCC about Ran. This study revealed the relationship between Ran expression and HNSCC characteristics, investigated the expression and role of Ran in HNSCC tissues and cells by means of immunohistochemistry, qRT-PCR, CCK-8, FCM and transwell migration assays. The results indicated that HNSCC tissues had significantly higher Ran expression than adjacent non-tumor tissues. The overall survival rate was significantly lower in patients with Ran-positive tumors than in those with Ran-negative tumors. Moreover, Ran was positively correlated with tumor grade, lymph node metastasis and recurrence. Ran was also high expressed in the HNSCC cell lines (PCI-37B and SCC9) and down regulated of Ran could evidently inhibit their proliferation, migration and down-regulate of Met protein. In conclusion, our findings suggested Ran could promote the proliferation and migration ability of HNSCC cells. Ran may play an important role in the development of HNSCC and may serve as a novel prognostic indicator of HNSCC.
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Affiliation(s)
- Chong Zhang
- Center for Implant Dentistry, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, China
| | - Xida Zhao
- Department of Periodontics and Oral Biology, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, China
| | - Weidong Du
- Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, China
| | - Jing Shen
- Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, China
| | - Siqi Li
- Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, China
| | - Zijia Li
- Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, China
| | - Zengxu Wang
- Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, China
| | - Fayu Liu
- Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Disease, Shenyang, China.
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17
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de Guillen K, Lorrain C, Tsan P, Barthe P, Petre B, Saveleva N, Rouhier N, Duplessis S, Padilla A, Hecker A. Structural genomics applied to the rust fungus Melampsora larici-populina reveals two candidate effector proteins adopting cystine knot and NTF2-like protein folds. Sci Rep 2019; 9:18084. [PMID: 31792250 PMCID: PMC6889267 DOI: 10.1038/s41598-019-53816-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 10/31/2019] [Indexed: 12/29/2022] Open
Abstract
Rust fungi are plant pathogens that secrete an arsenal of effector proteins interfering with plant functions and promoting parasitic infection. Effectors are often species-specific, evolve rapidly, and display low sequence similarities with known proteins. How rust fungal effectors function in host cells remains elusive, and biochemical and structural approaches have been scarcely used to tackle this question. In this study, we produced recombinant proteins of eleven candidate effectors of the leaf rust fungus Melampsora larici-populina in Escherichia coli. We successfully purified and solved the three-dimensional structure of two proteins, MLP124266 and MLP124017, using NMR spectroscopy. Although both MLP124266 and MLP124017 show no sequence similarity with known proteins, they exhibit structural similarities to knottins, which are disulfide-rich small proteins characterized by intricate disulfide bridges, and to nuclear transport factor 2-like proteins, which are molecular containers involved in a wide range of functions, respectively. Interestingly, such structural folds have not been reported so far in pathogen effectors, indicating that MLP124266 and MLP124017 may bear novel functions related to pathogenicity. Our findings show that sequence-unrelated effectors can adopt folds similar to known proteins, and encourage the use of biochemical and structural approaches to functionally characterize effector candidates.
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Affiliation(s)
- Karine de Guillen
- Centre de Biochimie Structurale (CBS), INSERM U1054, CNRS UMR 5048, Univ Montpellier, F-34090, Montpellier, France
| | - Cécile Lorrain
- Université de Lorraine, INRA, IAM, F-54000, Nancy, France
| | - Pascale Tsan
- Université de Lorraine, CNRS, CRM2, F-54000, Nancy, France
| | - Philippe Barthe
- Centre de Biochimie Structurale (CBS), INSERM U1054, CNRS UMR 5048, Univ Montpellier, F-34090, Montpellier, France
| | - Benjamin Petre
- Université de Lorraine, INRA, IAM, F-54000, Nancy, France
| | | | | | | | - André Padilla
- Centre de Biochimie Structurale (CBS), INSERM U1054, CNRS UMR 5048, Univ Montpellier, F-34090, Montpellier, France
| | - Arnaud Hecker
- Université de Lorraine, INRA, IAM, F-54000, Nancy, France.
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18
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Ren H, Xin G, Jia M, Zhu S, Lin Q, Wang X, Jiang Q, Zhang C. Postmitotic annulate lamellae assembly contributes to nuclear envelope reconstitution in daughter cells. J Biol Chem 2019; 294:10383-10391. [PMID: 31152066 DOI: 10.1074/jbc.ac119.008171] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 05/22/2019] [Indexed: 11/06/2022] Open
Abstract
In higher eukaryotic cells, the nuclear envelope (NE) is composed of double nuclear membranes studded with nuclear pore complexes (NPCs) and undergoes dynamic disassembly and reassembly during the cell cycle. However, how the NE and NPC reassemble remains largely unclear. Here, using HeLa, HEK293, and Drosophila cells, along with immunofluorescence microscopy and transmission EM methods, we found that postmitotic annulate lamellae (AL) assembly contributes to NE and NPC assembly. We observed that the AL are parallel membrane-pair stacks and possess regularly spaced AL pore complexes (ALPCs) that are morphologically similar to the NPCs. We found that the AL assemble in the cytoplasm during mitotic exit simultaneously with NE re-formation in daughter cells. Then, the assembled AL either bound the decondensing chromatin to directly transform into the NE or bound and fused with the outer nuclear membrane to join the assembling NE. The AL did not colocalize with sheet and tubular endoplasmic reticulum (ER) marker proteins on the ER or the lamin B receptor-localized membrane in the cytoplasm, suggesting that postmitotic AL assembly occurs independently of the chromatin and ER. Collectively, our results indicate that postmitotic AL assembly is a common cellular event and an intermediate step in NE and NPC assembly and in NE expansion in higher eukaryotic cells.
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Affiliation(s)
- He Ren
- From the Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Guangwei Xin
- From the Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Mingkang Jia
- From the Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Shicong Zhu
- From the Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Qiaoyu Lin
- From the Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Xiangyang Wang
- From the Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Qing Jiang
- From the Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing 100871, China
| | - Chuanmao Zhang
- From the Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, Beijing 100871, China
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19
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Mizuno Y, Ohtsu M, Shibata Y, Tanaka A, Camagna M, Ojika M, Mori H, Sato I, Chiba S, Kawakita K, Takemoto D. Nicotiana benthamiana RanBP1-1 Is Involved in the Induction of Disease Resistance via Regulation of Nuclear-Cytoplasmic Transport of Small GTPase Ran. FRONTIERS IN PLANT SCIENCE 2019; 10:222. [PMID: 30906303 PMCID: PMC6418045 DOI: 10.3389/fpls.2019.00222] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 02/08/2019] [Indexed: 06/07/2023]
Abstract
Plant cells enhance the tolerances to abiotic and biotic stresses via recognition of the stress, activation and nuclear import of signaling factors, up-regulation of defense genes, nuclear export of mRNA and translation of defense proteins. Nuclear pore-mediated transports should play critical roles in these processes, however, the regulatory mechanisms of nuclear-cytoplasmic transport during stress responses are largely unknown. In this study, a regulator of nuclear export of RNA and proteins, NbRanBP1-1 (Ran-binding protein1-1), was identified as an essential gene for the resistance of Nicotiana benthamiana to potato blight pathogen Phytophthora infestans. NbRanBP1-1-silenced plants showed delayed accumulation of capsidiol, a sesquiterpenoid phytoalexin, in response to elicitor treatment, and reduced resistance to P. infestans. Abnormal accumulation of mRNA was observed in NbRanBP1-1-silenced plants, indicating that NbRanBP1-1 is involved in the nuclear export of mRNA. In NbRanBP1-1-silenced plants, elicitor-induced expression of defense genes, NbEAS and NbWIPK, was not affected in the early stage of defense induction, but the accumulation of NbWIPK protein was reduced. Nuclear export of the small G-protein NbRan1a was activated during the induction of plant defense, whereas this process was compromised in NbRanBP1-1-silenced plants. Silencing of genes encoding the nuclear pore proteins, Nup75 and Nup160, also caused abnormal nuclear accumulation of mRNA, defects in the nuclear export of NbRan1a, and reduced production of capsidiol, resulting in decreased resistance to P. infestans. These results suggest that nuclear export of NbRan is a key event for defense induction in N. benthamiana, and both RanBP1-1 and nucleoporins play important roles in the process.
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20
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Wang S, Romano FB, Rapoport TA. Endoplasmic Reticulum Network Formation with Xenopus Egg Extracts. Cold Spring Harb Protoc 2019; 2019:pdb.prot097204. [PMID: 29475993 DOI: 10.1101/pdb.prot097204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The endoplasmic reticulum (ER) consists of morphologically distinct domains, including a polygonal network of tubules that is connected by three-way junctions. This network is found in all eukaryotic cells. Extracts from Xenopus laevis eggs contain stockpiles of components that allow the assembly of an ER network in vitro. Here we provide protocols for assembly of ER networks in extracts that are arrested at different stages of the cell cycle. Unfertilized Xenopus laevis eggs contain a cytostatic factor (CSF) that keeps them in the metaphase stage of the cell cycle. Disruption of the eggs by low-speed centrifugation releases calcium and the eggs cycle into interphase. This state can then be maintained by the addition of cycloheximide, which prevents the synthesis of cyclin B. CSF extracts can be also prepared in the presence of a calcium chelator, thus keeping the extract in metaphase. In this protocol, we outline procedures for the assembly of an ER network using either interphase- or metaphase-arrested Xenopus egg extracts. The network assembled is strikingly similar to the network observed in tissue culture cells. The extract allows easy biochemical manipulation, permitting the effects of purified proteins or small molecules, or the depletion of cytosolic components to be tested.
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Affiliation(s)
- Songyu Wang
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Fabian B Romano
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
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21
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Pappas SS, Liang CC, Kim S, Rivera CO, Dauer WT. TorsinA dysfunction causes persistent neuronal nuclear pore defects. Hum Mol Genet 2019; 27:407-420. [PMID: 29186574 DOI: 10.1093/hmg/ddx405] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 11/15/2017] [Indexed: 01/09/2023] Open
Abstract
A critical challenge to deciphering the pathophysiology of neurodevelopmental disease is identifying which of the myriad abnormalities that emerge during CNS maturation persist to contribute to long-term brain dysfunction. Childhood-onset dystonia caused by a loss-of-function mutation in the AAA+ protein torsinA exemplifies this challenge. Neurons lacking torsinA develop transient nuclear envelope (NE) malformations during CNS maturation, but no NE defects are described in mature torsinA null neurons. We find that during postnatal CNS maturation torsinA null neurons develop mislocalized and dysfunctional nuclear pore complexes (NPC) that lack NUP358, normally added late in NPC biogenesis. SUN1, a torsinA-related molecule implicated in interphase NPC biogenesis, also exhibits localization abnormalities. Whereas SUN1 and associated nuclear membrane abnormalities resolve in juvenile mice, NPC defects persist into adulthood. These findings support a role for torsinA function in NPC biogenesis during neuronal maturation and implicate altered NPC function in dystonia pathophysiology.
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Affiliation(s)
| | | | - Sumin Kim
- Cellular and Molecular Biology Program
| | | | - William T Dauer
- Department of Neurology.,Cellular and Molecular Biology Program.,Department of Cell and Developmental Biology.,VA Ann Arbor Health System, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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22
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Sheng C, Qiu J, Wang Y, He Z, Wang H, Wang Q, Huang Y, Zhu L, Shi F, Chen Y, Xiong S, Xu Z, Ni Q. Knockdown of Ran GTPase expression inhibits the proliferation and migration of breast cancer cells. Mol Med Rep 2018; 18:157-168. [PMID: 29750309 PMCID: PMC6059664 DOI: 10.3892/mmr.2018.8952] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 04/16/2018] [Indexed: 01/04/2023] Open
Abstract
Breast cancer is the second leading cause of cancer-associated mortality in women worldwide. Strong evidence has suggested that Ran, which is a small GTP binding protein involved in the transport of RNA and protein across the nucleus, may be a key cellular protein involved in the metastatic progression of cancer. The present study investigated Ran gene expression in breast cancer tissue samples obtained from 140 patients who had undergone surgical resection for breast cancer. Western blot analysis of Ran in breast cancer tissues and paired adjacent normal tissues showed that expression of Ran was significantly increased in breast cancer tissues. Immunohistochemistry analyses conducted on formalin-fixed paraffin-embedded breast cancer tissue sections revealed that Ran expression was associated with tumor histological grade, nerve invasion and metastasis, vascular metastasis and Ki-67 expression (a marker of cell proliferation). Kaplan-Meier survival analysis showed that increased Ran expression in patients with breast cancer was positively associated with a poor survival prognosis. Furthermore, in vitro experiments demonstrated that highly migratory MDA-MB-231 cancer cells treated with Ran-si-RNA (si-Ran), which knocked down expression of Ran, exhibited decreased motility in trans-well migration and wound healing assays. Cell cycle analysis of Ran knocked down MDA-MB-231 cells implicated Ran in cell cycle arrest and the inhibition of proliferation. Furthermore, a starvation and re-feeding (CCK-8) assay was performed, which indicated that Ran regulated breast cancer cell proliferation. Taken together, the results provide strong in vitro evidence of the involvement of Ran in the progression of breast cancer and suggest that it could have high potential as a therapeutic target and/or marker of disease.
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Affiliation(s)
- Chenyi Sheng
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Jian Qiu
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Yingying Wang
- Surgical Comprehensive Laboratory, Medical School of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Zhixian He
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Hua Wang
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Qingqing Wang
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Yeqing Huang
- Department of Pathology, Affiliated Cancer Hospital of Nantong University, Nantong, Jiangsu 226361, P.R. China
| | - Lianxin Zhu
- Department of Surgical Oncology, Lu'an People's Hospital Tumor Center, The Lu'an Affiliated Hospital of Anhui Medical University, Lu'an, Anhui 237000, P.R. China
| | - Feng Shi
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Yingying Chen
- Surgical Comprehensive Laboratory, Medical School of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Shiyao Xiong
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Zhen Xu
- Surgical Comprehensive Laboratory, Medical School of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Qichao Ni
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
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23
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Zhang Q, Wang B, Wei J, Wang X, Han Q, Kang Z. TaNTF2, a contributor for wheat resistance to the stripe rust pathogen. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2018; 123:260-267. [PMID: 29274571 DOI: 10.1016/j.plaphy.2017.12.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 12/11/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Nuclear Transport Factor 2 (NTF2) functions as a critical regulator in balancing the GTP-and GDP-bound forms of Ran, a class of evolutionarily conserved small GTP-binding protein. During the incompatible interaction between wheat-Puccinia striiformis f. sp. tritici (Pst), a cDNA fragment encoding a putative wheat NTF2 gene was found to be significantly induced, suggesting a potential role in wheat resistance to Pst. In this work, the full length of TaNTF2 was obtained, with three copies located on 7A, 7B and 7D chromosomes, respectively. QRT-PCR further verified the up-regulated expression of TaNTF2 in response to avirulent Pst. In addition, TaNTF2 was also induced by exogenous hormone applications, especially JA treatment. Transient expression of TaNTF2 in tobacco cells confirmed its subcellular localization in the cytoplasm, perinuclear area and nucleus. And virus induced gene silencing (VIGS) was used to identify the function of TaNTF2 during an incompatible wheat-Pst interaction. When TaNTF2 was knocked down, resistance of wheat to avirulentPst was decreased, with a bigger necrotic spots, and higher numbers of hyphal branches and haustorial mother cells. Our results demonstrated that TaNTF2 was a contributor for wheat resistance to the stripe rust pathogen, which will help to comprehensively understand the NTF2/Ran modulating mechanism in wheat-Pst interaction.
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Affiliation(s)
- Qiong Zhang
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Bing Wang
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Jinping Wei
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xiaojie Wang
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Qingmei Han
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, China.
| | - Zhensheng Kang
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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24
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Otsuka S, Ellenberg J. Mechanisms of nuclear pore complex assembly - two different ways of building one molecular machine. FEBS Lett 2018; 592:475-488. [PMID: 29119545 PMCID: PMC6220763 DOI: 10.1002/1873-3468.12905] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 10/27/2017] [Accepted: 11/02/2017] [Indexed: 12/16/2022]
Abstract
The nuclear pore complex (NPC) mediates all macromolecular transport across the nuclear envelope. In higher eukaryotes that have an open mitosis, NPCs assemble at two points in the cell cycle: during nuclear assembly in late mitosis and during nuclear growth in interphase. How the NPC, the largest nonpolymeric protein complex in eukaryotic cells, self-assembles inside cells remained unclear. Recent studies have started to uncover the assembly process, and evidence has been accumulating that postmitotic and interphase NPC assembly use fundamentally different mechanisms; the duration, structural intermediates, and regulation by molecular players are different and different types of membrane deformation are involved. In this Review, we summarize the current understanding of these two modes of NPC assembly and discuss the structural and regulatory steps that might drive the assembly processes. We furthermore integrate understanding of NPC assembly with the mechanisms for rapid nuclear growth in embryos and, finally, speculate on the evolutionary origin of the NPC implied by the presence of two distinct assembly mechanisms.
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Affiliation(s)
- Shotaro Otsuka
- Cell Biology and Biophysics UnitEuropean Molecular Biology LaboratoryHeidelbergGermany
| | - Jan Ellenberg
- Cell Biology and Biophysics UnitEuropean Molecular Biology LaboratoryHeidelbergGermany
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25
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Ferencz C, Guigas G, Veres A, Neumann B, Stemmann O, Weiss M. In Vitro Reconstitution of the Endoplasmic Reticulum. ACTA ACUST UNITED AC 2017; 76:11.22.1-11.22.16. [DOI: 10.1002/cpcb.30] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Csilla‐Maria Ferencz
- Department of Experimental Physics I, University of Bayreuth Bayreuth Germany
- Current address: Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio‐Systems Potsdam Germany
| | - Gernot Guigas
- Department of Experimental Physics I, University of Bayreuth Bayreuth Germany
- Current address: Institute of Applied Physics, Karlsruhe Institute of Technology (KIT) Karlsruhe Germany
| | - Andreas Veres
- Department of Experimental Physics I, University of Bayreuth Bayreuth Germany
| | | | - Olaf Stemmann
- Department of Genetics, University of Bayreuth Bayreuth Germany
| | - Matthias Weiss
- Department of Experimental Physics I, University of Bayreuth Bayreuth Germany
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26
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Kaufmann T, Kukolj E, Brachner A, Beltzung E, Bruno M, Kostrhon S, Opravil S, Hudecz O, Mechtler K, Warren G, Slade D. SIRT2 regulates nuclear envelope reassembly through ANKLE2 deacetylation. J Cell Sci 2016; 129:4607-4621. [PMID: 27875273 PMCID: PMC5201015 DOI: 10.1242/jcs.192633] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Accepted: 11/09/2016] [Indexed: 12/18/2022] Open
Abstract
Sirtuin 2 (SIRT2) is an NAD-dependent deacetylase known to regulate microtubule dynamics and cell cycle progression. SIRT2 has also been implicated in the pathology of cancer, neurodegenerative diseases and progeria. Here, we show that SIRT2 depletion or overexpression causes nuclear envelope reassembly defects. We link this phenotype to the recently identified regulator of nuclear envelope reassembly ANKLE2. ANKLE2 acetylation at K302 and phosphorylation at S662 are dynamically regulated throughout the cell cycle by SIRT2 and are essential for normal nuclear envelope reassembly. The function of SIRT2 therefore extends beyond the regulation of microtubules to include the regulation of nuclear envelope dynamics.
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Affiliation(s)
- Tanja Kaufmann
- Department of Biochemistry, Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, Vienna 1030, Austria.,Department of Molecular Biotechnology, University of Applied Sciences FH Campus Wien, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria
| | - Eva Kukolj
- Department of Biochemistry, Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, Vienna 1030, Austria
| | - Andreas Brachner
- Department of Biochemistry, Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, Vienna 1030, Austria
| | - Etienne Beltzung
- Department of Biochemistry, Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, Vienna 1030, Austria
| | - Melania Bruno
- Department of Biochemistry, Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, Vienna 1030, Austria
| | - Sebastian Kostrhon
- Department of Biochemistry, Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, Vienna 1030, Austria
| | - Susanne Opravil
- Institute of Molecular Pathology, Dr Bohr-Gasse 7, Vienna 1030, Austria
| | - Otto Hudecz
- Institute of Molecular Pathology, Dr Bohr-Gasse 7, Vienna 1030, Austria
| | - Karl Mechtler
- Institute of Molecular Pathology, Dr Bohr-Gasse 7, Vienna 1030, Austria
| | - Graham Warren
- Department of Biochemistry, Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, Vienna 1030, Austria
| | - Dea Slade
- Department of Biochemistry, Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, Vienna 1030, Austria
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Shaping the endoplasmic reticulum in vitro. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2035-2040. [PMID: 27287725 DOI: 10.1016/j.bbamem.2016.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/02/2016] [Accepted: 06/05/2016] [Indexed: 11/22/2022]
Abstract
Organelles in eukaryotic cells often have complex shapes that deviate significantly from simple spheres. A prime example is the endoplasmic reticulum (ER) that forms an extensive network of membrane tubules in many mammalian cell types and in reconstitution assays in vitro. Despite the successful hunt for molecular determinants of ER shape we are still far from having a comprehensive understanding of ER network morphogenesis. Here, we have studied the hitherto neglected influence of the host substrate when reconstituting ER networks in vitro as compared to ER networks in vivo. In culture cells we observed cytoplasm-spanning ER networks with tubules being connected almost exclusively by three-way junctions and segment lengths being narrowly distributed around a mean length of about 1μm. In contrast, networks reconstituted from purified ER microsomes on flat glass or gel substrates of varying stiffness showed significantly broader length distributions with an up to fourfold larger mean length. Self-assembly of ER microsomes on small oil droplets, however, yielded networks that resembled more closely the native ER network of mammalian cells. We conclude from these observations that the ER microsomes' inherent self-assembly capacity is sufficient to support network formation with a native geometry if the influence of the host substrate's surface chemistry becomes negligible. We hypothesize that under these conditions the networks' preference for three-way junctions follows from creating 'starfish-shaped' vesicles when ER microsomes with a protein-induced spontaneous curvature undergo fusion.
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Abstract
According to the standard model of G protein-coupled receptor (GPCR) signaling, GPCRs are localized to the cell membrane where they respond to extracellular signals. Stimulation of GPCRs leads to the activation of heterotrimeric G proteins and their intracellular signaling pathways. However, this model fails to accommodate GPCRs, G proteins, and their downstream effectors that are found on the nuclear membrane or in the nucleus. Evidence from isolated nuclei indicates the presence of GPCRs on the nuclear membrane that can activate similar G protein-dependent signaling pathways in the nucleus as at the cell surface. These pathways also include activation of cyclic adenosine monophosphate, calcium and nitric oxide synthase signaling in cardiomyocytes. In addition, a number of distinct heterotrimeric and monomeric G proteins have been found in the nucleus of various cell types. This review will focus on understanding the function of nuclear G proteins with a focus on cardiac signaling where applicable.
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Chen JWC, Barker AR, Wakefield JG. The Ran Pathway in Drosophila melanogaster Mitosis. Front Cell Dev Biol 2015; 3:74. [PMID: 26636083 PMCID: PMC4659922 DOI: 10.3389/fcell.2015.00074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/09/2015] [Indexed: 11/29/2022] Open
Abstract
Over the last two decades, the small GTPase Ran has emerged as a central regulator of both mitosis and meiosis, particularly in the generation, maintenance, and regulation of the microtubule (MT)-based bipolar spindle. Ran-regulated pathways in mitosis bear many similarities to the well-characterized functions of Ran in nuclear transport and, as with transport, the majority of these mitotic effects are mediated through affecting the physical interaction between karyopherins and Spindle Assembly Factors (SAFs)—a loose term describing proteins or protein complexes involved in spindle assembly through promoting nucleation, stabilization, and/or depolymerization of MTs, through anchoring MTs to specific structures such as centrosomes, chromatin or kinetochores, or through sliding MTs along each other to generate the force required to achieve bipolarity. As such, the Ran-mediated pathway represents a crucial functional module within the wider spindle assembly landscape. Research into mitosis using the model organism Drosophila melanogaster has contributed substantially to our understanding of centrosome and spindle function. However, in comparison to mammalian systems, very little is known about the contribution of Ran-mediated pathways in Drosophila mitosis. This article sets out to summarize our understanding of the roles of the Ran pathway components in Drosophila mitosis, focusing on the syncytial blastoderm embryo, arguing that it can provide important insights into the conserved functions on Ran during spindle formation.
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Affiliation(s)
- Jack W C Chen
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Amy R Barker
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK ; Centre for Microvascular Research, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London London, UK
| | - James G Wakefield
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
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30
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Schellhaus AK, De Magistris P, Antonin W. Nuclear Reformation at the End of Mitosis. J Mol Biol 2015; 428:1962-85. [PMID: 26423234 DOI: 10.1016/j.jmb.2015.09.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/17/2015] [Accepted: 09/19/2015] [Indexed: 12/17/2022]
Abstract
Cells have developed highly sophisticated ways to accurately pass on their genetic information to the daughter cells. In animal cells, which undergo open mitosis, the nuclear envelope breaks down at the beginning of mitosis and the chromatin massively condenses to be captured and segregated by the mitotic spindle. These events have to be reverted in order to allow the reformation of a nucleus competent for DNA transcription and replication, as well as all other nuclear processes occurring in interphase. Here, we summarize our current knowledge of how, in animal cells, the highly compacted mitotic chromosomes are decondensed at the end of mitosis and how a nuclear envelope, including functional nuclear pore complexes, reassembles around these decondensing chromosomes.
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Affiliation(s)
| | - Paola De Magistris
- Friedrich Miescher Laboratory of the Max Planck Society, Spemannstrasse 39, 72076 Tübingen, Germany
| | - Wolfram Antonin
- Friedrich Miescher Laboratory of the Max Planck Society, Spemannstrasse 39, 72076 Tübingen, Germany.
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31
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Abstract
Chromosomes are not only carriers of the genetic material, but also actively regulate the assembly of complex intracellular architectures. During mitosis, chromosome-induced microtubule polymerisation ensures spindle assembly in cells without centrosomes and plays a supportive role in centrosome-containing cells. Chromosomal signals also mediate post-mitotic nuclear envelope (NE) re-formation. Recent studies using novel approaches to manipulate histones in oocytes, where functions can be analysed in the absence of transcription, have established that nucleosomes, but not DNA alone, mediate the chromosomal regulation of spindle assembly and NE formation. Both processes require the generation of RanGTP by RCC1 recruited to nucleosomes but nucleosomes also acquire cell cycle stage specific regulators, Aurora B in mitosis and ELYS, the initiator of nuclear pore complex assembly, at mitotic exit. Here, we review the mechanisms by which nucleosomes control assembly and functions of the spindle and the NE, and discuss their implications for genome maintenance.
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Affiliation(s)
- Christian Zierhut
- Laboratory of Chromosome and Cell Biology, Rockefeller University, New York, NY, USA
| | - Hironori Funabiki
- Laboratory of Chromosome and Cell Biology, Rockefeller University, New York, NY, USA
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32
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Remaut K, Symens N, Lucas B, Demeester J, De Smedt SC. Cell division responsive peptides for optimized plasmid DNA delivery: the mitotic window of opportunity? J Control Release 2014; 179:1-9. [PMID: 24462902 DOI: 10.1016/j.jconrel.2014.01.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 01/07/2014] [Accepted: 01/13/2014] [Indexed: 10/25/2022]
Abstract
The delivery of plasmid DNA remains hard to achieve, especially due to the presence of the nuclear membrane barrier. During cell division, however, the nuclear membrane is temporarily disassembled. We evaluated two different strategies to optimize plasmid DNA delivery in dividing cells: 1) phosphorylation responsive peptides that release plasmid DNA preferentially during mitosis and 2) chromatin targeting peptides to anchor plasmid DNA in newly formed nuclei upon cell division. Peptide/DNA particles alone were not efficient in penetrating cells. Upon co-delivery with lipid-based carriers, however, transfection efficiency drastically improved when compared to controls. For the phosphorylation responsive peptides, the presence of the phosphorylation sequence slightly increased transfection efficiency. For the chromatin targeting peptides, however, the chromatin targeting sequence did not seem to be the main reason for the improvement of transfection efficiency when applied in living cells. In conclusion, the pre-condensation of plasmid DNA with peptides improves lipid based delivery, but the nature of the peptides (cell responsive or not) does not seem to be the main reason for the improvement. It seems that the nuclear entry of foreign plasmid DNA is still under tight control, even during the mitotic window of opportunity.
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Affiliation(s)
- K Remaut
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - N Symens
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - B Lucas
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - J Demeester
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - S C De Smedt
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium.
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33
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Bernis C, Forbes DJ. Analysis of nuclear reconstitution, nuclear envelope assembly, and nuclear pore assembly using Xenopus in vitro assays. Methods Cell Biol 2014; 122:165-91. [PMID: 24857730 DOI: 10.1016/b978-0-12-417160-2.00008-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The large and complex eukaryotic nucleus is the arbiter of DNA replication, RNA transcription, splicing, and ribosome assembly. With the advent of in vitro nuclear reconstitution extracts derived from Xenopus eggs in the 1980s, it became possible to assemble multiple nuclei in vitro around added DNA or chromatin substrates. Such reconstituted nuclei contain a nuclear lamina, double nuclear membranes, nuclear pores, and are competent for DNA replication and nuclear import. In vitro nuclear reconstitution has allowed the assembly of "wild-type" and "biochemically mutant" nuclei in which the impact of individual components can be assessed. Here, we describe protocols for preparation of the nuclear reconstitution extract, nuclear reconstitution in vitro, assessment of nuclear membrane integrity, and a more specialized assay for nuclear pore assembly into preformed pore-free nuclear intermediates.
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Affiliation(s)
- Cyril Bernis
- Cell and Developmental Biology, University of California, San Diego, California, USA
| | - Douglass J Forbes
- Cell and Developmental Biology, University of California, San Diego, California, USA
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34
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Ran GTPase in nuclear envelope formation and cancer metastasis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:323-51. [PMID: 24563355 DOI: 10.1007/978-1-4899-8032-8_15] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ran is a small ras-related GTPase that controls the nucleocytoplasmic exchange of macromolecules across the nuclear envelope. It binds to chromatin early during nuclear formation and has important roles during the eukaryotic cell cycle, where it regulates mitotic spindle assembly, nuclear envelope formation and cell cycle checkpoint control. Like other GTPases, Ran relies on the cycling between GTP-bound and GDP-bound conformations to interact with effector proteins and regulate these processes. In nucleocytoplasmic transport, Ran shuttles across the nuclear envelope through nuclear pores. It is concentrated in the nucleus by an active import mechanism where it generates a high concentration of RanGTP by nucleotide exchange. It controls the assembly and disassembly of a range of complexes that are formed between Ran-binding proteins and cellular cargo to maintain rapid nuclear transport. Ran also has been identified as an essential protein in nuclear envelope formation in eukaryotes. This mechanism is dependent on importin-β, which regulates the assembly of further complexes important in this process, such as Nup107-Nup160. A strong body of evidence is emerging implicating Ran as a key protein in the metastatic progression of cancer. Ran is overexpressed in a range of tumors, such as breast and renal, and these perturbed levels are associated with local invasion, metastasis and reduced patient survival. Furthermore, tumors with oncogenic KRAS or PIK3CA mutations are addicted to Ran expression, which yields exciting future therapeutic opportunities.
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35
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Wang S, Romano FB, Field CM, Mitchison TJ, Rapoport TA. Multiple mechanisms determine ER network morphology during the cell cycle in Xenopus egg extracts. ACTA ACUST UNITED AC 2013; 203:801-14. [PMID: 24297752 PMCID: PMC3857478 DOI: 10.1083/jcb.201308001] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Fusion of ER membranes by atlastin and interaction of ER with growing microtubule ends and dynein cooperate to generate distinct ER morphologies during the cell cycle. In metazoans the endoplasmic reticulum (ER) changes during the cell cycle, with the nuclear envelope (NE) disassembling and reassembling during mitosis and the peripheral ER undergoing extensive remodeling. Here we address how ER morphology is generated during the cell cycle using crude and fractionated Xenopus laevis egg extracts. We show that in interphase the ER is concentrated at the microtubule (MT)-organizing center by dynein and is spread by outward extension of ER tubules through their association with plus ends of growing MTs. Fusion of membranes into an ER network is dependent on the guanosine triphosphatase atlastin (ATL). NE assembly requires fusion by both ATL and ER-soluble N-ethyl-maleimide–sensitive factor adaptor protein receptors. In mitotic extracts, the ER converts into a network of sheets connected by ER tubules and loses most of its interactions with MTs. Together, these results indicate that fusion of ER membranes by ATL and interaction of ER with growing MT ends and dynein cooperate to generate distinct ER morphologies during the cell cycle.
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Affiliation(s)
- Songyu Wang
- Department of Cell Biology and Howard Hughes Medical Institute and 2 Department of Systems Biology, Harvard Medical School, Boston, MA 02115
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36
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Identification of a PTC-containing DlRan transcript and its differential expression during somatic embryogenesis in Dimocarpus longan. Gene 2013; 529:37-44. [DOI: 10.1016/j.gene.2013.07.091] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/19/2013] [Accepted: 07/25/2013] [Indexed: 11/17/2022]
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37
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Xue JZ, Woo EM, Postow L, Chait BT, Funabiki H. Chromatin-bound Xenopus Dppa2 shapes the nucleus by locally inhibiting microtubule assembly. Dev Cell 2013; 27:47-59. [PMID: 24075807 DOI: 10.1016/j.devcel.2013.08.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/19/2013] [Accepted: 08/05/2013] [Indexed: 10/26/2022]
Abstract
Nuclear shape and size vary between species, during development, and in many tissue pathologies, but the causes and effects of these differences remain poorly understood. During fertilization, sperm nuclei undergo a dramatic conversion from a heavily compacted form into decondensed, spherical pronuclei, accompanied by rapid nucleation of microtubules from centrosomes. Here we report that the assembly of the spherical nucleus depends on a critical balance of microtubule dynamics, which is regulated by the chromatin-binding protein Developmental pluripotency-associated 2 (Dppa2). Whereas microtubules normally promote sperm pronuclear expansion, in Dppa2-depleted Xenopus egg extracts excess microtubules cause pronuclear assembly defects, leading to abnormal morphology and disorganized DNA replication. Dppa2 inhibits microtubule polymerization in vitro, and Dppa2 activity is needed at a precise time and location during nascent pronuclear formation. This demonstrates a strict spatiotemporal requirement for local suppression of microtubules during nuclear formation, fulfilled by chromatin-bound microtubule regulators.
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Affiliation(s)
- John Z Xue
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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38
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Regner B, Vučinić D, Domnisoru C, Bartol T, Hetzer M, Tartakovsky D, Sejnowski T. Anomalous diffusion of single particles in cytoplasm. Biophys J 2013; 104:1652-60. [PMID: 23601312 PMCID: PMC3627875 DOI: 10.1016/j.bpj.2013.01.049] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 01/18/2013] [Accepted: 01/24/2013] [Indexed: 11/20/2022] Open
Abstract
The crowded intracellular environment poses a formidable challenge to experimental and theoretical analyses of intracellular transport mechanisms. Our measurements of single-particle trajectories in cytoplasm and their random-walk interpretations elucidate two of these mechanisms: molecular diffusion in crowded environments and cytoskeletal transport along microtubules. We employed acousto-optic deflector microscopy to map out the three-dimensional trajectories of microspheres migrating in the cytosolic fraction of a cellular extract. Classical Brownian motion (BM), continuous time random walk, and fractional BM were alternatively used to represent these trajectories. The comparison of the experimental and numerical data demonstrates that cytoskeletal transport along microtubules and diffusion in the cytosolic fraction exhibit anomalous (nonFickian) behavior and posses statistically distinct signatures. Among the three random-walk models used, continuous time random walk provides the best representation of diffusion, whereas microtubular transport is accurately modeled with fractional BM.
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Affiliation(s)
- Benjamin M. Regner
- Department of Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, California
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California
| | - Dejan Vučinić
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California
| | - Cristina Domnisoru
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California
- Princeton Neuroscience Institute, Lewis-Sigler Institute for Integrative Genomics, Department of Molecular Biology, Princeton University, Princeton, New Jersey
| | - Thomas M. Bartol
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California
| | - Martin W. Hetzer
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California
| | - Daniel M. Tartakovsky
- Department of Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, California
| | - Terrence J. Sejnowski
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California
- The Division of Biological Studies Sciences, University of California at San Diego, La Jolla, California
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39
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The permeability of reconstituted nuclear pores provides direct evidence for the selective phase model. Cell 2012; 150:738-51. [PMID: 22901806 DOI: 10.1016/j.cell.2012.07.019] [Citation(s) in RCA: 218] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/05/2012] [Accepted: 06/05/2012] [Indexed: 11/20/2022]
Abstract
Nuclear pore complexes (NPCs) maintain a permeability barrier between the nucleus and the cytoplasm through FG-repeat-containing nucleoporins (Nups). We previously proposed a "selective phase model" in which the FG repeats interact with one another to form a sieve-like barrier that can be locally disrupted by the binding of nuclear transport receptors (NTRs), but not by inert macromolecules, allowing selective passage of NTRs and associated cargo. Here, we provide direct evidence for this model in a physiological context. By using NPCs reconstituted from Xenopus laevis egg extracts, we show that Nup98 is essential for maintaining the permeability barrier. Specifically, the multivalent cohesion between FG repeats is required, including cohesive FG repeats close to the anchorage point to the NPC scaffold. Our data exclude alternative models that are based solely on an interaction between the FG repeats and NTRs and indicate that the barrier is formed by a sieve-like FG hydrogel.
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40
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Building a nuclear envelope at the end of mitosis: coordinating membrane reorganization, nuclear pore complex assembly, and chromatin de-condensation. Chromosoma 2012; 121:539-54. [PMID: 23104094 PMCID: PMC3501164 DOI: 10.1007/s00412-012-0388-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/04/2012] [Accepted: 10/04/2012] [Indexed: 12/01/2022]
Abstract
The metazoan nucleus is disassembled and re-built at every mitotic cell division. The nuclear envelope, including nuclear pore complexes, breaks down at the beginning of mitosis to accommodate the capture of massively condensed chromosomes by the spindle apparatus. At the end of mitosis, a nuclear envelope is newly formed around each set of segregating and de-condensing chromatin. We review the current understanding of the membrane restructuring events involved in the formation of the nuclear membrane sheets of the envelope, the mechanisms governing nuclear pore complex assembly and integration in the nascent nuclear membranes, and the regulated coordination of these events with chromatin de-condensation.
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41
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Chromatin-bound NLS proteins recruit membrane vesicles and nucleoporins for nuclear envelope assembly via importin-α/β. Cell Res 2012; 22:1562-75. [PMID: 22847741 DOI: 10.1038/cr.2012.113] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The mechanism for nuclear envelope (NE) assembly is not fully understood. Importin-β and the small GTPase Ran have been implicated in the spatial regulation of NE assembly process. Here we report that chromatin-bound NLS (nuclear localization sequence) proteins provide docking sites for the NE precursor membrane vesicles and nucleoporins via importin-α and -β during NE assembly in Xenopus egg extracts. We show that along with the fast recruitment of the abundant NLS proteins such as nucleoplasmin and histones to the demembranated sperm chromatin in the extracts, importin-α binds the chromatin NLS proteins rapidly. Meanwhile, importin-β binds cytoplasmic NE precursor membrane vesicles and nucleoporins. Through interacting with importin-α on the chromatin NLS proteins, importin-β targets the membrane vesicles and nucleoporins to the chromatin surface. Once encountering Ran-GTP on the chromatin generated by RCC1, importin-β preferentially binds Ran-GTP and releases the membrane vesicles and nucleoporins for NE assembly. NE assembly is disrupted by blocking the interaction between importin-α and NLS proteins with excess soluble NLS proteins or by depletion of importin-β from the extract. Our findings reveal a novel molecular mechanism for NE assembly in Xenopus egg extracts.
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42
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Dynamics of PLCγ and Src family kinase 1 interactions during nuclear envelope formation revealed by FRET-FLIM. PLoS One 2012; 7:e40669. [PMID: 22848394 PMCID: PMC3404105 DOI: 10.1371/journal.pone.0040669] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 06/11/2012] [Indexed: 01/10/2023] Open
Abstract
The nuclear envelope (NE) breaks down and reforms during each mitotic cycle. A similar process happens to the sperm NE following fertilisation. The formation of the NE in both these circumstances involves endoplasmic reticulum membranes enveloping the chromatin, but PLCγ-dependent membrane fusion events are also essential. Here we demonstrate the activation of PLCγ by a Src family kinase (SFK1) during NE assembly. We show by time-resolved FRET for the first time the direct in vivo interaction and temporal regulation of PLCγ and SFK1 in sea urchins. As a prerequisite for protein activation, there is a rapid phosphorylation of PLCγ on its Y783 residue in response to GTP in vitro. This phosphorylation is dependent upon SFK activity; thus Y783 phosphorylation and NE assembly are susceptible to SFK inhibition. Y783 phosphorylation is also observed on the surface of the male pronucleus (MPN) in vivo during NE formation. Together the corroborative in vivo and in vitro data demonstrate the phosphorylation and activation of PLCγ by SFK1 during NE assembly. We discuss the potential generality of such a mechanism.
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43
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Müller S. Universal rules for division plane selection in plants. PROTOPLASMA 2012; 249:239-53. [PMID: 21611883 DOI: 10.1007/s00709-011-0289-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 05/16/2011] [Indexed: 05/08/2023]
Abstract
Coordinated cell divisions and cell expansion are the key processes that command growth in all organisms. The orientation of cell divisions and the direction of cell expansion are critical for normal development. Symmetric divisions contribute to proliferation and growth, while asymmetric divisions initiate pattern formation and differentiation. In plants these processes are of particular importance since their cells are encased in cellulosic walls that determine their shape and lock their position within tissues and organs. Several recent studies have analyzed the relationship between cell shape and patterns of symmetric cell division in diverse organisms and employed biophysical and mathematical considerations to develop computer simulations that have allowed accurate prediction of cell division patterns. From these studies, a picture emerges that diverse biological systems follow simple universal rules of geometry to select their division planes and that the microtubule cytoskeleton takes a major part in sensing the geometric information and translates this information into a specific division outcome. In plant cells, the division plane is selected before mitosis, and spatial information of the division plane is preserved throughout division by the presence of reference molecules at a distinct region of the plasma membrane, the cortical division zone. The recruitment of these division zone markers occurs multiple times by several mechanisms, suggesting that the cortical division zone is a highly dynamic region.
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Affiliation(s)
- Sabine Müller
- Center for Plant Molecular Biology-Developmental Genetics, University of Tübingen, Auf der Morgenstelle 3, 72076, Tübingen, Germany.
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44
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Shaulov L, Gruber R, Cohen I, Harel A. A dominant-negative form of POM121 binds chromatin and disrupts the two separate modes of nuclear pore assembly. J Cell Sci 2011; 124:3822-34. [PMID: 22100917 DOI: 10.1242/jcs.086660] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Nuclear pore complexes (NPCs) are formed during two separate stages of the metazoan cell cycle. They are assembled into the re-forming nuclear envelope (NE) at the exit from mitosis and into an intact, expanding NE during interphase. Here, we show that a soluble internal fragment of the membrane nucleoporin POM121 has a dominant-negative effect on both modes of assembly in a cell-free reconstitution system. The soluble POM121 fragment binds chromatin at sites that are distinct from ELYS-Nup107-160 'seeding' sites and prevents membrane enclosure and NPC formation. Importin-β negatively regulates chromatin binding by the POM121 fragment through a conserved NLS motif and is also shown to affect the recruitment of the endogenous membrane protein to chromatin in the full assembly system. When an intact NE is present before the addition of the dominant-negative fragment, NPCs are inserted into the NE but membrane expansion is inhibited. This results in densely packed NPCs with no intervening membrane patches, as visualized by scanning electron microscopy. We conclude that POM121 plays an important role in both modes of assembly and links nuclear membrane formation and expansion to nuclear pore biogenesis.
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Affiliation(s)
- Lihi Shaulov
- Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
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45
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The site of RanGTP generation can act as an organizational cue for mitotic microtubules. Biol Cell 2011; 103:421-34. [PMID: 21692748 DOI: 10.1042/bc20100135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND INFORMATION RanGTP, which is generated on chromosomes during mitosis, is required for microtubule spindle assembly. Due to its restricted spatial generation within the cell it has been suggested that RanGTP acts as a spatial cue to organize site-specific spindle assembly within the cell. However, the absence of a detectable sharp gradient of RanGTP in somatic cells has led to suggestions that it may only act as a spatial cue in large cells and that it may operate as a general activator of the mitotic cytosol in somatic cells. RESULTS We report that ectopic generation of RanGTP at the plasma membrane stimulates the formation of organized arrays of microtubules at the plasma membrane. CONCLUSIONS These results suggest that the site of RanGTP generation in a mitotic somatic cell can generate critical spatial information that specifies where microtubules grow towards and where microtubules are organized. As RanGTP is normally generated on chromosomes, these results suggest that RanGTP may play an important role in specifying that spindle assembly occurs around chromosomes.
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46
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Tseng LC, Chen RH. Temporal control of nuclear envelope assembly by phosphorylation of lamin B receptor. Mol Biol Cell 2011; 22:3306-17. [PMID: 21795390 PMCID: PMC3172257 DOI: 10.1091/mbc.e11-03-0199] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 07/06/2011] [Accepted: 07/18/2011] [Indexed: 01/13/2023] Open
Abstract
The nuclear envelope of metazoans disassembles during mitosis and reforms in late anaphase after sister chromatids have well separated. The coordination of these mitotic events is important for genome stability, yet the temporal control of nuclear envelope reassembly is unknown. Although the steps of nuclear formation have been extensively studied in vitro using the reconstitution system from egg extracts, the temporal control can only be studied in vivo. Here, we use time-lapse microscopy to investigate this process in living HeLa cells. We demonstrate that Cdk1 activity prevents premature nuclear envelope assembly and that phosphorylation of the inner nuclear membrane protein lamin B receptor (LBR) by Cdk1 contributes to the temporal control. We further identify a region in the nucleoplasmic domain of LBR that inhibits premature chromatin binding of the protein. We propose that this inhibitory effect is partly mediated by Cdk1 phosphorylation. Furthermore, we show that the reduced chromatin-binding ability of LBR together with Aurora B activity contributes to nuclear envelope breakdown. Our studies reveal for the first time a mechanism that controls the timing of nuclear envelope reassembly through modification of an integral nuclear membrane protein.
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Affiliation(s)
- Li-Chuan Tseng
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
| | - Rey-Huei Chen
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
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47
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Symens N, Walczak R, Demeester J, Mattaj I, De Smedt SC, Remaut K. Nuclear inclusion of nontargeted and chromatin-targeted polystyrene beads and plasmid DNA containing nanoparticles. Mol Pharm 2011; 8:1757-66. [PMID: 21859089 DOI: 10.1021/mp200120v] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nuclear membrane is one of the major cellular barriers in the delivery of plasmid DNA (pDNA). Cell division has a positive influence on the expression efficiency since, at the end of mitosis, pDNA or pDNA containing complexes near the chromatin are probably included by a random process in the nuclei of the daughter cells. However, very little is known about the nuclear inclusion of nanoparticles during cell division. Using the Xenopus nuclear envelope reassembly (XNER) assay, we found that the nuclear enclosure of nanoparticles was dependent on size (with 100 and 200 nm particles being better included than the 500 nm ones) and charge (with positively charged particles being better included than negatively charged or polyethyleneglycolated (PEGylated) ones) of the beads. Also, coupling chromatin-targeting peptides to the polystyrene beads or pDNA complexes improved their inclusion by 2- to 3-fold. Upon microinjection in living HeLa cells, however, nanoparticles were never observed in the nuclei of cells postdivision but accumulated in a specific perinuclear region, which was identified as the lysosomal compartment. This indicates that nanoparticles can end up in the lysosomes even when they were not delivered through endocytosis. To elucidate if the chromatin binding peptides also have potential in living cells, this additional barrier first has to be tackled, since it prevents free particles from being present near the chromatin at the moment of cell division.
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Affiliation(s)
- Nathalie Symens
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent Research Group on Nanomedicines, Faculty of Pharmaceutical Sciences, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
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48
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Talamas JA, Hetzer MW. POM121 and Sun1 play a role in early steps of interphase NPC assembly. ACTA ACUST UNITED AC 2011; 194:27-37. [PMID: 21727197 PMCID: PMC3135402 DOI: 10.1083/jcb.201012154] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
POM121 and Sun1, but not the Nup107–160 complex, are required for fusion of the inner and outer nuclear membrane during nuclear pore assembly in interphase of the cell cycle. Nuclear pore complexes (NPCs) assemble at the end of mitosis during nuclear envelope (NE) reformation and into an intact NE as cells progress through interphase. Although recent studies have shown that NPC formation occurs by two different molecular mechanisms at two distinct cell cycle stages, little is known about the molecular players that mediate the fusion of the outer and inner nuclear membranes to form pores. In this paper, we provide evidence that the transmembrane nucleoporin (Nup), POM121, but not the Nup107–160 complex, is present at new pore assembly sites at a time that coincides with inner nuclear membrane (INM) and outer nuclear membrane (ONM) fusion. Overexpression of POM121 resulted in juxtaposition of the INM and ONM. Additionally, Sun1, an INM protein that is known to interact with the cytoskeleton, was specifically required for interphase assembly and localized with POM121 at forming pores. We propose a model in which POM121 and Sun1 interact transiently to promote early steps of interphase NPC assembly.
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Affiliation(s)
- Jessica A Talamas
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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Lavoie C, Roy L, Lanoix J, Taheri M, Young R, Thibault G, Farah CA, Leclerc N, Paiement J. Taking organelles apart, putting them back together and creating new ones: lessons from the endoplasmic reticulum. ACTA ACUST UNITED AC 2011; 46:1-48. [PMID: 21536318 DOI: 10.1016/j.proghi.2011.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2011] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is a highly dynamic organelle. It is composed of four subcompartments including nuclear envelope (NE), rough ER (rER), smooth ER (sER) and transitional ER (tER). The subcompartments are interconnected, can fragment and dissociate and are able to reassemble again. They coordinate with cell function by way of protein regulators in the surrounding cytosol. The activity of the many associated molecular machines of the ER as well as the fluid nature of the limiting membrane of the ER contribute extensively to the dynamics of the ER. This review examines the properties of the ER that permit its isolation and purification and the physiological conditions that permit reconstitution both in vitro and in vivo in normal and in disease conditions.
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Affiliation(s)
- Christine Lavoie
- Département de pharmacologie, Faculté de médecine, Université de Sherbrooke, Sherbrooke, QC, Canada
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50
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Rodrigo-Peiris T, Xu XM, Zhao Q, Wang HJ, Meier I. RanGAP is required for post-meiotic mitosis in female gametophyte development in Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:2705-14. [PMID: 21282324 DOI: 10.1093/jxb/erq448] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
RanGAP is the GTPase-activating protein of the small GTPase Ran and is involved in nucleocytoplasmic transport in yeast and animals via the Ran cycle and in mitotic cell division. Arabidopsis thaliana has two copies of RanGAP, RanGAP1 and RanGAP2. To investigate the function of plant RanGAP, T-DNA insertional mutants were analysed. Arabidopsis plants with a null mutant of either RanGAP1 or RanGAP2 had no observable phenotype. Analysis of segregating progeny showed that double mutants in RanGAP1 and RanGAP2 are female gametophyte defective. Ovule clearing with differential interference contrast optics showed that mutant female gametophytes were arrested at interphase, predominantly after the first mitotic division following meiosis. In contrast, mutant pollen developed and functioned normally. These results show that the two RanGAPs are redundant and indispensable for female gametophyte development in Arabidopsis but dispensable for pollen development. Nuclear division arrest during a mitotic stage suggests a role for plant RanGAP in mitotic cell cycle progression during female gametophyte development.
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Affiliation(s)
- Thushani Rodrigo-Peiris
- Department of Plant Cellular and Molecular Biology, The Ohio State University, Columbus, OH 43210, USA
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