1
|
Liashkovich I, Rosso G, Shahin V. Atomic Force Microscopy for Structural and Biophysical Investigations on Nuclear Pore Complexes. Methods Mol Biol 2022; 2502:299-310. [PMID: 35412247 DOI: 10.1007/978-1-0716-2337-4_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Atomic force microscopy (AFM) enables simultaneous generation of topographical and biophysical maps of surfaces of biological samples at nanoresolution in physiologically relevant environments. Here, we describe the application of AFM to study nuclear pore complexes from structural and biophysical aspects.
Collapse
Affiliation(s)
- Ivan Liashkovich
- Institute of Physiology II, University of Münster, Münster, Germany
| | - Gonzalo Rosso
- Institute of Physiology II, University of Münster, Münster, Germany
| | - Victor Shahin
- Institute of Physiology II, University of Münster, Münster, Germany.
| |
Collapse
|
2
|
Fichtman B, Regmi SG, Dasso M, Harel A. High-Resolution Imaging and Analysis of Individual Nuclear Pore Complexes. Methods Mol Biol 2022; 2502:461-471. [PMID: 35412256 PMCID: PMC11166266 DOI: 10.1007/978-1-0716-2337-4_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Field emission scanning electron microscopy (FESEM) is a well-established technique for acquiring three-dimensional surface images of nuclear pore complexes (NPCs). We present an optimized protocol for the exposure of mammalian cell nuclei and direct surface imaging of nuclear envelopes by FESEM, allowing for a detailed morphological comparison of individual NPCs, without the need for averaging techniques. This provides a unique high resolution tool for studying the effects of cellular stress, specific genetic manipulations and inherited diseases on the ultrastructure of human NPCs.
Collapse
Affiliation(s)
- Boris Fichtman
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Saroj G Regmi
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Mary Dasso
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Amnon Harel
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel.
| |
Collapse
|
3
|
The Cytoskeleton and Its Roles in Self-Organization Phenomena: Insights from Xenopus Egg Extracts. Cells 2021; 10:cells10092197. [PMID: 34571847 PMCID: PMC8465277 DOI: 10.3390/cells10092197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/18/2021] [Accepted: 08/21/2021] [Indexed: 01/11/2023] Open
Abstract
Self-organization of and by the cytoskeleton is central to the biology of the cell. Since their introduction in the early 1980s, cytoplasmic extracts derived from the eggs of the African clawed-frog, Xenopus laevis, have flourished as a major experimental system to study the various facets of cytoskeleton-dependent self-organization. Over the years, the many investigations that have used these extracts uniquely benefited from their simplified cell cycle, large experimental volumes, biochemical tractability and cell-free nature. Here, we review the contributions of egg extracts to our understanding of the cytoplasmic aspects of self-organization by the microtubule and the actomyosin cytoskeletons as well as the importance of cytoskeletal filaments in organizing nuclear structure and function.
Collapse
|
4
|
Wesolowska N, Avilov I, Machado P, Geiss C, Kondo H, Mori M, Lenart P. Actin assembly ruptures the nuclear envelope by prying the lamina away from nuclear pores and nuclear membranes in starfish oocytes. eLife 2020; 9:49774. [PMID: 31989921 PMCID: PMC7028370 DOI: 10.7554/elife.49774] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 01/24/2020] [Indexed: 01/04/2023] Open
Abstract
The nucleus of oocytes (germinal vesicle) is unusually large and its nuclear envelope (NE) is densely packed with nuclear pore complexes (NPCs) that are stockpiled for embryonic development. We showed that breakdown of this specialized NE is mediated by an Arp2/3-nucleated F-actin ‘shell’ in starfish oocytes, in contrast to microtubule-driven tearing in mammalian fibroblasts. Here, we address the mechanism of F-actin-driven NE rupture by correlated live-cell, super-resolution and electron microscopy. We show that actin is nucleated within the lamina, sprouting filopodia-like spikes towards the nuclear membranes. These F-actin spikes protrude pore-free nuclear membranes, whereas the adjoining stretches of membrane accumulate NPCs that are associated with the still-intact lamina. Packed NPCs sort into a distinct membrane network, while breaks appear in ER-like, pore-free regions. We reveal a new function for actin-mediated membrane shaping in nuclear rupture that is likely to have implications in other contexts, such as nuclear rupture observed in cancer cells.
Collapse
Affiliation(s)
- Natalia Wesolowska
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Ivan Avilov
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Pedro Machado
- Electron Microscopy Core Facility, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Celina Geiss
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Hiroshi Kondo
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Masashi Mori
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Peter Lenart
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.,Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| |
Collapse
|
5
|
Bilir Ş, Kojidani T, Mori C, Osakada H, Kobayashi S, Koujin T, Hiraoka Y, Haraguchi T. Roles of Nup133, Nup153 and membrane fenestrations in assembly of the nuclear pore complex at the end of mitosis. Genes Cells 2019; 24:338-353. [PMID: 30821042 DOI: 10.1111/gtc.12677] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 02/15/2019] [Accepted: 02/24/2019] [Indexed: 12/25/2022]
Abstract
Reassembly of the nuclear pore complex (NPC) at the end of mitosis is an important event for eukaryotic nuclear function. In this study, we examined the dynamic behaviors of the endoplasmic reticulum (ER) by "Live CLEM" imaging. In metaphase, numerous fenestrations on the ER membrane were observed around chromosomes. In telophase, these fenestrations became filled at the region attached to chromosomes, whereas they remained open at the region unattached to chromosomes, suggesting that NPC assembly takes place at fenestrations on the membrane. To determine the roles of nucleoporins in postmitotic NPC formation, we used artificial beads conjugated with anti-GFP antibody, which captures GFP-fused proteins on the beads when incorporated into cells. Live CLEM imaging of telophase cells containing Nup133-coated beads or Nup153-coated beads showed that Nup133 and Nup153, as the sole effector molecules, assembled the NPC-like structure on the membrane fenestrations. Indirect immunofluorescence staining of the Nup133-coated beads showed that Nup133 effectively assembled Nup107 and ELYS, whereas minimal assembly of Nup98 and Nup62 was observed; the Nup153-coated bead effectively assembled Nup98, Nup62 and Pom121, but assembled neither Nup107 nor ELYS. Our results suggest that Nup133 and Nup153 play different roles in assembling the NPC on membrane fenestrations.
Collapse
Affiliation(s)
- Şükriye Bilir
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.,Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe, Japan
| | - Tomoko Kojidani
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe, Japan.,Japan Women's University, Tokyo, Japan
| | - Chie Mori
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe, Japan
| | - Shouhei Kobayashi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe, Japan
| | - Takako Koujin
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.,Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.,Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe, Japan
| |
Collapse
|
6
|
Iwamoto M, Fukuda Y, Osakada H, Mori C, Hiraoka Y, Haraguchi T. Identification of the evolutionarily conserved nuclear envelope proteins Lem2 and MicLem2 in Tetrahymena thermophila. Gene 2019; 721S:100006. [PMID: 32550543 PMCID: PMC7285967 DOI: 10.1016/j.gene.2019.100006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/18/2018] [Accepted: 01/11/2019] [Indexed: 11/26/2022]
Abstract
Lem2 family proteins, i.e. the LAP2-Emerin-MAN1 (LEM) domain-containing nuclear envelope proteins, are well-conserved from yeasts to humans, both of which belong to the Opisthokonta supergroup. However, whether their homologs are present in other eukaryotic phylogenies remains unclear. In this study, we identified two Lem2 homolog proteins, which we named as Lem2 and MicLem2, in a ciliate Tetrahymena thermophila belonging to the SAR supergroup. Lem2 was localized to the nuclear envelope of the macronucleus (MAC) and micronucleus (MIC), while MicLem2 was exclusively localized to the nuclear envelope of the MIC. Immunoelectron microscopy revealed that Lem2 in T. thermophila was localized to both the inner and outer nuclear envelopes of the MAC and MIC, while MicLem2 was mostly localized to the nuclear pores of the MIC. Molecular domain analysis using GFP-fused protein showed that the N-terminal and luminal domains, including the transmembrane segments, are responsible for nuclear envelope localization. During sexual reproduction, enrichment of Lem2 occurred in the nuclear envelopes of the MAC and MIC to be degraded, while MicLem2 was enriched in the nuclear envelope of the MIC that escaped degradation. These findings suggest the unique characteristics of Tetrahymena Lem2 proteins. Our findings provide insight into the evolutionary divergence of nuclear envelope proteins. Conserved nuclear envelope proteins Lem2 and MicLem2 are identified in Tetrahymena. Lem2 is localized to the nuclear envelope of the macronucleus and the micronucleus. MicLem2 is localized to the nuclear pore complex of the micronucleus. In sexual reproduction, Lem2 is enriched to the nuclei assigned to degradation. MicLem2 is enriched to the micronuclei that are escaped from degradation.
Collapse
Key Words
- BAF, barrier-to-autointegration factor
- DAPI, 4′,6‑diamidino‑2‑phenylindole
- DDW, double distilled water
- EDTA, ethylenediaminetetraacetic acid
- ER, endoplasmic reticulum
- GA, glutaraldehyde
- HeH domain
- HeH, helix-extension-helix
- LAP2, lamina associated polypeptide 2
- LEM domain
- LEM, LAP2-Emerin-MAN1
- MAC, macronucleus
- MIC, micronucleus
- MSC domain
- MSC, Man1-Src1p-C-terminal
- Man1
- Man1-Src1p-C-terminal domain
- NE, nuclear envelope
- NLS, nuclear localization signal
- NPC, nuclear pore complex
- Nuclear dimorphism
- Nuclear envelope
- ONM and INM, outer and inner nuclear membranes
- PB, phosphate buffer
- PBS, phosphate buffered saline
- Protist
- RRM, RNA recognition motif
- TM, transmembrane
Collapse
Affiliation(s)
- Masaaki Iwamoto
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Yasuhiro Fukuda
- Graduate School of Agricultural Science, Tohoku University, Osaki, 989-6711, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Chie Mori
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| |
Collapse
|
7
|
Shen XD, Hou F, Chen J, Jiang XY, Zou SM. Identification of nuclear localization signal within goldfish Tgf2 transposase. Gene 2016; 593:21-27. [PMID: 27468946 DOI: 10.1016/j.gene.2016.07.060] [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: 05/30/2016] [Revised: 07/12/2016] [Accepted: 07/24/2016] [Indexed: 10/21/2022]
Abstract
The structure of goldfish (Carassius auratus) Tgf2 transposase is still poorly understood, although it can mediate efficient gene transfer in teleost fish. We hypothesized the existence of a nuclear localization signal (NLS) within Tgf2 transposase to assist transport into the nucleus. To explore this, 15 consecutive amino acid residues (656-670 aa) within the C-terminus of Tgf2 transposase were predicted in silico to be a NLS domain. The pEGFP-C1-Tgf2TP(△31C) plasmid encoding the NLS-domain-deleted Tgf2 transposase fused to EGFP was constructed, and transfected into 293T cells. After transfection with pEGFP-C1-Tgf2TP(△31C), EGFP was not detected in the nucleus alone, while 67.0% of cells expressed EGFP only in the cytoplasm. In contrast, after transfection with control plasmids containing C- or N-terminal truncated Tgf2 transposases with an intact NLS domain, EGFP was not detected in the cytoplasm alone, while approximately 40% of cells expressed EGFP only in the nucleus, and the remaining 60% expressed EGFP in both the nucleus and cytoplasm. Our results demonstrated that loss of the NLS domain results in expression in the cytoplasm but not in the nucleus. These findings suggest that 15 aa residues located from 656 to 670 aa within the C-terminus of Tgf2 transposase can function as a NLS to assist the transfer of the transposase into the nucleus where it mediates DNA transposition.
Collapse
Affiliation(s)
- Xiao-Dan Shen
- Key Laboratory of Genetic Resources for Freshwater Aquaculture and Fisheries, Shanghai Ocean University, 999 Huchenghuan Road, Shanghai 201306, China
| | - Fei Hou
- Key Laboratory of Genetic Resources for Freshwater Aquaculture and Fisheries, Shanghai Ocean University, 999 Huchenghuan Road, Shanghai 201306, China
| | - Jie Chen
- Key Laboratory of Genetic Resources for Freshwater Aquaculture and Fisheries, Shanghai Ocean University, 999 Huchenghuan Road, Shanghai 201306, China
| | - Xia-Yun Jiang
- Key Laboratory of Genetic Resources for Freshwater Aquaculture and Fisheries, Shanghai Ocean University, 999 Huchenghuan Road, Shanghai 201306, China.
| | - Shu-Ming Zou
- Key Laboratory of Genetic Resources for Freshwater Aquaculture and Fisheries, Shanghai Ocean University, 999 Huchenghuan Road, Shanghai 201306, China.
| |
Collapse
|
8
|
Raghunayakula S, Subramonian D, Dasso M, Kumar R, Zhang XD. Molecular Characterization and Functional Analysis of Annulate Lamellae Pore Complexes in Nuclear Transport in Mammalian Cells. PLoS One 2015; 10:e0144508. [PMID: 26642330 PMCID: PMC4671610 DOI: 10.1371/journal.pone.0144508] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/19/2015] [Indexed: 01/26/2023] Open
Abstract
Annulate lamellae are cytoplasmic organelles containing stacked sheets of membranes embedded with pore complexes. These cytoplasmic pore complexes at annulate lamellae are morphologically similar to nuclear pore complexes at the nuclear envelope. Although annulate lamellae has been observed in nearly all types of cells, their biological functions are still largely unknown. Here we show that SUMO1-modification of the Ran GTPase-activating protein RanGAP1 not only target RanGAP1 to its known sites at nuclear pore complexes but also to annulate lamellae pore complexes through interactions with the Ran-binding protein RanBP2 and the SUMO-conjugating enzyme Ubc9 in mammalian cells. Furthermore, upregulation of annulate lamellae, which decreases the number of nuclear pore complexes and concurrently increases that of annulate lamellae pore complexes, causes a redistribution of nuclear transport receptors including importin α/β and the exportin CRM1 from nuclear pore complexes to annulate lamellae pore complexes and also reduces the rates of nuclear import and export. Moreover, our results reveal that importin α/β-mediated import complexes initially accumulate at annulate lamellae pore complexes upon the activation of nuclear import and subsequently disassociate for nuclear import through nuclear pore complexes in cells with upregulation of annulate lamellae. Lastly, CRM1-mediated export complexes are concentrated at both nuclear pore complexes and annulate lamellae pore complexes when the disassembly of these export complexes is inhibited by transient expression of a Ran GTPase mutant arrested in its GTP-bound form, suggesting that RanGAP1/RanBP2-activated RanGTP hydrolysis at these pore complexes is required for the dissociation of the export complexes. Hence, our findings provide a foundation for further investigation of how upregulation of annulate lamellae decreases the rates of nuclear transport and also for elucidation of the biological significance of the interaction between annulate lamellae pore complexes and nuclear transport complexes in mammalian cells.
Collapse
Affiliation(s)
- Sarita Raghunayakula
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Divya Subramonian
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Mary Dasso
- Laboratory of Gene Regulation and Development, National Institute for Child Health and Human Development, NIH, Bethesda, Maryland, United States of America
| | - Rita Kumar
- Departments of Emergency Medicine and Physiology, Wayne State University, Detroit, Michigan, United States of America
| | - Xiang-Dong Zhang
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| |
Collapse
|
9
|
Koo AJ, Thireault C, Zemelis S, Poudel AN, Zhang T, Kitaoka N, Brandizzi F, Matsuura H, Howe GA. Endoplasmic reticulum-associated inactivation of the hormone jasmonoyl-L-isoleucine by multiple members of the cytochrome P450 94 family in Arabidopsis. J Biol Chem 2014; 289:29728-38. [PMID: 25210037 PMCID: PMC4207986 DOI: 10.1074/jbc.m114.603084] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 09/09/2014] [Indexed: 01/13/2023] Open
Abstract
The plant hormone jasmonate (JA) controls diverse aspects of plant immunity, growth, and development. The amplitude and duration of JA responses are controlled in large part by the intracellular level of jasmonoyl-L-isoleucine (JA-Ile). In contrast to detailed knowledge of the JA-Ile biosynthetic pathway, little is known about enzymes involved in JA-Ile metabolism and turnover. Cytochromes P450 (CYP) 94B3 and 94C1 were recently shown to sequentially oxidize JA-Ile to hydroxy (12OH-JA-Ile) and dicarboxy (12COOH-JA-Ile) derivatives. Here, we report that a third member (CYP94B1) of the CYP94 family also participates in oxidative turnover of JA-Ile in Arabidopsis. In vitro studies showed that recombinant CYP94B1 converts JA-Ile to 12OH-JA-Ile and lesser amounts of 12COOH-JA-Ile. Consistent with this finding, metabolic and physiological characterization of CYP94B1 loss-of-function and overexpressing plants demonstrated that CYP94B1 and CYP94B3 coordinately govern the majority (>95%) of 12-hydroxylation of JA-Ile in wounded leaves. Analysis of CYP94-promoter-GUS reporter lines indicated that CYP94B1 and CYP94B3 serve unique and overlapping spatio-temporal roles in JA-Ile homeostasis. Subcellular localization studies showed that CYP94s involved in conversion of JA-Ile to 12COOH-JA-Ile reside on endoplasmic reticulum (ER). In vitro studies further showed that 12COOH-JA-Ile, unlike JA-Ile, fails to promote assembly of COI1-JAZ co-receptor complexes. The double loss-of-function mutant of CYP94B3 and ILL6, a JA-Ile amidohydrolase, displayed a JA profile consistent with the collaborative action of the oxidative and the hydrolytic pathways in JA-Ile turnover. Collectively, our results provide an integrated view of how multiple ER-localized CYP94 and JA amidohydrolase enzymes attenuate JA signaling during stress responses.
Collapse
Affiliation(s)
- Abraham J Koo
- From the Department of Energy-Plant Research Laboratory and the Division of Biochemistry, Interdisciplinary Plant Group, and
| | | | - Starla Zemelis
- From the Department of Energy-Plant Research Laboratory and
| | - Arati N Poudel
- the Division of Biochemistry, Interdisciplinary Plant Group, and Division of Plant Sciences, University of Missouri, Columbia, Missouri 65211
| | - Tong Zhang
- the Division of Biochemistry, Interdisciplinary Plant Group, and
| | - Naoki Kitaoka
- Division of Applied Bioscience, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan, and
| | | | - Hideyuki Matsuura
- Division of Applied Bioscience, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan, and
| | - Gregg A Howe
- From the Department of Energy-Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
| |
Collapse
|
10
|
Ibarra C, Vicencio JM, Varas-Godoy M, Jaimovich E, Rothermel BA, Uhlén P, Hill JA, Lavandero S. An integrated mechanism of cardiomyocyte nuclear Ca(2+) signaling. J Mol Cell Cardiol 2014; 75:40-8. [PMID: 24997440 PMCID: PMC4626248 DOI: 10.1016/j.yjmcc.2014.06.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 06/11/2014] [Accepted: 06/26/2014] [Indexed: 01/05/2023]
Abstract
In cardiomyocytes, Ca(2+) plays a central role in governing both contraction and signaling events that regulate gene expression. Current evidence indicates that discrimination between these two critical functions is achieved by segregating Ca(2+) within subcellular microdomains: transcription is regulated by Ca(2+) release within nuclear microdomains, and excitation-contraction coupling is regulated by cytosolic Ca(2+). Accordingly, a variety of agonists that control cardiomyocyte gene expression, such as endothelin-1, angiotensin-II or insulin-like growth factor-1, share the feature of triggering nuclear Ca(2+) signals. However, signaling pathways coupling surface receptor activation to nuclear Ca(2+) release, and the phenotypic responses to such signals, differ between agonists. According to earlier hypotheses, the selective control of nuclear Ca(2+) signals by activation of plasma membrane receptors relies on the strategic localization of inositol trisphosphate receptors at the nuclear envelope. There, they mediate Ca(2+) release from perinuclear Ca(2+) stores upon binding of inositol trisphosphate generated in the cytosol, which diffuses into the nucleus. More recently, identification of such receptors at nuclear membranes or perinuclear sarcolemmal invaginations has uncovered novel mechanisms whereby agonists control nuclear Ca(2+) release. In this review, we discuss mechanisms for the selective control of nuclear Ca(2+) signals with special focus on emerging models of agonist receptor activation.
Collapse
Affiliation(s)
- Cristián Ibarra
- Cardiovascular and Metabolic Diseases, Innovative Medicines and Early Development, AstraZeneca R&D, Mölndal, Sweden.
| | - Jose Miguel Vicencio
- Hatter Cardiovascular Institute, University College London, London, United Kingdom
| | - Manuel Varas-Godoy
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Enrique Jaimovich
- Centro de Estudios Moleculares de la Célula, Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Beverly A Rothermel
- Department of Internal Medicine, Cardiology Division, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Per Uhlén
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Joseph A Hill
- Department of Internal Medicine, Cardiology Division, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Sergio Lavandero
- Centro de Estudios Moleculares de la Célula, Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile; Department of Internal Medicine, Cardiology Division, University of Texas Southwestern Medical Center, Dallas, TX, USA; Advanced Center for Chronic Diseases, Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile.
| |
Collapse
|
11
|
Kunda A, Krishnan NH, Krishnan VV. Mapping the amino acid properties of constituent nucleoporins onto the yeast nuclear pore complex. Bioinformation 2014; 10:94-7. [PMID: 24616561 PMCID: PMC3937582 DOI: 10.6026/97320630010094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 01/04/2014] [Accepted: 01/06/2014] [Indexed: 11/28/2022] Open
Abstract
Visualization of molecular structures aids in the understanding of structural and functional roles of biological macromolecules. Macromolecular transport between the cell nucleus and cytoplasm is facilitated by the nuclear pore complex (NPC). The ring structure of the NPC is large and contains several distinct proteins (nucleoporins) which function as a selective gate for the passage of certain molecules into and out of the nucleus. In this note we demonstrate the utility of a python code that allows direct mapping of the physiochemical properties of the constituent nucleoporins on the scaffold of the yeast NPC׳s cytoplasmic view. We expect this tool to be useful for researchers to visualize the NPC based on their physiochemical properties and how it alters when specific mutations are introduced in one or more of the nucleoporins. The code developed using Python is available freely from the authors.
Collapse
Affiliation(s)
- Ashok Kunda
- Davis Senior High School, 315 West 14th Street, Davis, CA 95616
- Contributed equally
| | - Narayanan H Krishnan
- Davis Senior High School, 315 West 14th Street, Davis, CA 95616
- Contributed equally
| | - VV Krishnan
- Department of Chemistry, California State University, Fresno CA 93740 and
- Department of Medical Pathology and Laboratory Medicine, University of California Davis School of Medicine,Davis, CA 95616
| |
Collapse
|
12
|
Shaulov L, Fichtman B, Harel A. High-resolution scanning electron microscopy for the imaging of nuclear pore complexes and Ran-mediated transport. Methods Mol Biol 2014; 1120:253-261. [PMID: 24470031 DOI: 10.1007/978-1-62703-791-4_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
High-resolution scanning electron microscopy provides three-dimensional surface images of nuclear pore complexes (NPCs) embedded in the nuclear envelope. Here, we describe a method for exposing the nuclear surface in mammalian tissue culture cells for imaging by scanning electron microscopy. Hypotonic treatment is followed by low-speed centrifugation onto polylysine-coated silicon chips, without the use of detergents. This helps to preserve NPCs close to their native morphology, embedded in undamaged nuclear membranes. This method is particularly advantageous for combining high-resolution imaging of NPCs with mammalian genetic systems.
Collapse
Affiliation(s)
- Lihi Shaulov
- Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel
| | | | | |
Collapse
|
13
|
Fiserova J, Spink M, Richards SA, Saunter C, Goldberg MW. Entry into the nuclear pore complex is controlled by a cytoplasmic exclusion zone containing dynamic GLFG-repeat nucleoporin domains. J Cell Sci 2013; 127:124-36. [PMID: 24144701 DOI: 10.1242/jcs.133272] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nuclear pore complexes (NPCs) mediate nucleocytoplasmic movement. The central channel contains proteins with phenylalanine-glycine (FG) repeats, or variations (GLFG, glycine-leucine-phenylalanine-glycine). These are 'intrinsically disordered' and often represent weak interaction sites that become ordered upon interaction. We investigated this possibility during nuclear transport. Using electron microscopy of S. cerevisiae, we show that NPC cytoplasmic filaments form a dome-shaped structure enclosing GLFG domains. GLFG domains extend out of this structure and are part of an 'exclusion zone' that might act as a partial barrier to entry of transport-inert proteins. The anchor domain of a GLFG nucleoporin locates exclusively to the central channel. By contrast, the localisation of the GLFG domains varied between NPCs and could be cytoplasmic, central or nucleoplasmic and could stretch up to 80 nm. These results suggest a dynamic exchange between ordered and disordered states. In contrast to diffusion through the NPC, transport cargoes passed through the exclusion zone and accumulated near the central plane. We also show that movement of cargo through the NPC is accompanied by relocation of GLFG domains, suggesting that binding, restructuring and movement of these domains could be part of the translocation mechanism.
Collapse
Affiliation(s)
- Jindriska Fiserova
- School of Biological and Biomedical Sciences, Durham University, Science Laboratories, South Road, Durham DH1 3LE, UK
| | | | | | | | | |
Collapse
|
14
|
Sutter E, de Oliveira AP, Tobler K, Schraner EM, Sonda S, Kaech A, Lucas MS, Ackermann M, Wild P. Herpes simplex virus 1 induces de novo phospholipid synthesis. Virology 2012; 429:124-35. [PMID: 22560864 DOI: 10.1016/j.virol.2012.04.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 03/02/2012] [Accepted: 04/10/2012] [Indexed: 11/25/2022]
Abstract
Herpes simplex virus type 1 capsids bud at nuclear membranes and Golgi membranes acquiring an envelope composed of phospholipids. Hence, we measured incorporation of phospholipid precursors into these membranes, and quantified changes in size of cellular compartments by morphometric analysis. Incorporation of [³H]-choline into both nuclear and cytoplasmic membranes was significantly enhanced upon infection. [³H]-choline was also part of isolated virions even grown in the presence of brefeldin A. Nuclei expanded early in infection. The Golgi complex and vacuoles increased substantially whereas the endoplasmic reticulum enlarged only temporarily. The data suggest that HSV-1 stimulates phospholipid synthesis, and that de novo synthesized phospholipids are inserted into nuclear and cytoplasmic membranes to i) maintain membrane integrity in the course of nuclear and cellular expansion, ii) to supply membrane constituents for envelopment of capsids by budding at nuclear membranes and Golgi membranes, and iii) to provide membranes for formation of transport vacuoles.
Collapse
Affiliation(s)
- Esther Sutter
- Electron Microscopy, Institute of Veterinary Anatomy, University of Zürich, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Shaulov L, Harel A. Improved Visualization of Vertebrate Nuclear Pore Complexes by Field Emission Scanning Electron Microscopy. Structure 2012; 20:407-13. [DOI: 10.1016/j.str.2012.01.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 01/29/2012] [Accepted: 01/31/2012] [Indexed: 10/28/2022]
|
16
|
Goodsell DS. Miniseries: Illustrating the machinery of life: Eukaryotic cell panorama. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 39:91-101. [PMID: 21445900 DOI: 10.1002/bmb.20494] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Diverse biological data may be used to create illustrations of molecules in their cellular context. This report describes the scientific results that support an illustration of a eukaryotic cell, enlarged by one million times to show the distribution and arrangement of macromolecules. The panoramic cross section includes eight panels that extend from the nucleus to the cell surface, showing the process of protein synthesis and export. Results from biochemistry, electron microscopy, NMR spectroscopy and x-ray crystallography were used to create the image.
Collapse
Affiliation(s)
- David S Goodsell
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92102, USA.
| |
Collapse
|
17
|
Abstract
Although the potential benefits of gene therapy for the treatment of acquired and inherited genetic diseases have been demonstrated through preclinical studies, the results of human gene therapy trials have been disappointing. Recombinant viruses are the primary vectors of choice because of their ability to protect genetic materials, cross cellular membranes, escape from endosomes and transport their genetic materials into the nucleus. Unfortunately, viral vectors have been unable to gain widespread clinical application because of their toxicity and immunogenicity. Consequently, the need for safer alternatives has led to the development of liposomes, cationic polyplexes, microparticles and nanoparticles. Although these alternative vectors have shown promise, degradable nanoparticles are the only non-viral vectors that can provide a targeted intracellular delivery with controlled release properties. Furthermore, the potential advantage of degradable nanoparticles over their non-degradable counterparts is the reduced toxicity and the avoidance of accumulation within the target tissue after repeated administration. In this article, current non-viral gene delivery devices are reviewed with a special emphasis on nanoparticle gene delivery systems. Also, the authors highlight their philosophy and efforts on the development of l-tyrosine-based polyphosphate nanoparticle-based non-viral gene delivery systems and assess the potential benefits and shortcomings of their approach.
Collapse
Affiliation(s)
- Andrew J Ditto
- The University of Akron, Sidney Olson Research Center, Department of Biomedical Engineering, Akron, OH 44325, USA
| | | | | |
Collapse
|
18
|
Wild P, Senn C, Manera CL, Sutter E, Schraner EM, Tobler K, Ackermann M, Ziegler U, Lucas MS, Kaech A. Exploring the nuclear envelope of herpes simplex virus 1-infected cells by high-resolution microscopy. J Virol 2009; 83:408-19. [PMID: 18922868 PMCID: PMC2612326 DOI: 10.1128/jvi.01568-08] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Accepted: 10/06/2008] [Indexed: 01/11/2023] Open
Abstract
Herpesviruses are composed of capsid, tegument, and envelope. Capsids assemble in the nucleus and exit the nucleus by budding at the inner nuclear membrane, acquiring tegument and the envelope. This study focuses on the changes of the nuclear envelope during herpes simplex virus 1 (HSV-1) infection in HeLa and Vero cells by employing preparation techniques at ambient and low temperatures for high-resolution scanning and transmission electron microscopy and confocal laser scanning microscopy. Cryo-field emission scanning electron microscopy of freeze-fractured cells showed for the first time budding of capsids at the nuclear envelope at the third dimension with high activity at 10 h and low activity at 15 h of incubation. The mean number of pores was significantly lower, and the mean interpore distance and the mean interpore area were significantly larger than those for mock-infected cells 15 h after inoculation. Forty-five percent of nuclear pores in HSV-1-infected cells were dilated to more than 140 nm. Nuclear material containing capsids protrude through them into the cytoplasm. Examination of in situ preparations after dry fracturing revealed significant enlargements of the nuclear pore diameter and of the nuclear pore central channel in HSV-1-infected cells compared to mock-infected cells. The demonstration of nucleoporins by confocal microscopy also revealed fewer pores but focal enhancement of fluorescence signals in HSV-1-infected cells, whereas Western blots showed no loss of nucleoporins from cells. The data suggest that infection with HSV-1 alters the number, size, and architecture of nuclear pores without a loss of nucleoporins from altered nuclear pore complexes.
Collapse
Affiliation(s)
- Peter Wild
- Electron Microscopy, Institute of Virology, Winterthurerstrasse 266a, CH-8057 Zürich, Switzerland.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Severe acute respiratory syndrome coronavirus protein 6 accelerates murine hepatitis virus infections by more than one mechanism. J Virol 2008; 82:7212-22. [PMID: 18448520 DOI: 10.1128/jvi.02406-07] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) encodes numerous accessory proteins whose importance in the natural infection process is currently unclear. One of these accessory proteins is set apart by its function in the context of a related murine hepatitis virus (MHV) infection. SARS-CoV protein 6 increases MHV neurovirulence and accelerates MHV infection kinetics in tissue culture. Protein 6 also blocks nuclear import of macromolecules from the cytoplasm, a process known to involve its C-terminal residues interacting with cellular importins. In this study, protein 6 was expressed from plasmid DNAs and accumulated in cells prior to infection by wild-type MHV. Output of MHV progeny was significantly increased by preexisting protein 6. Protein 6 with C-terminal deletion mutations no longer interfered with nuclear import processes but still retained much of the capacity to augment MHV infections. However, some virus growth-enhancing activity could be ascribed to the C-terminal end of protein 6. To determine whether this augmentation provided by the C terminus was derived from interference with nuclear import, we evaluated the virus-modulating effects of small interfering RNAs (siRNAs) directed against importin-beta mRNAs, which down-regulated classical nuclear import pathways. The siRNAs did indeed prime cells for enhanced MHV infection. Our findings indicated that protein 6-mediated nuclear import blocks augmented MHV infections but is clearly not the only way that this accessory protein operates to create a milieu conducive to robust virus growth. Thus, the SARS-CoV protein 6 accelerates MHV infections by more than one mechanism.
Collapse
|
20
|
Effect of wastewater treatment plant effluent on microbial function and community structure in the sediment of a freshwater stream with variable seasonal flow. Appl Environ Microbiol 2008; 74:2659-68. [PMID: 18344343 DOI: 10.1128/aem.02348-07] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the effects of wastewater treatment plant (WWTP) discharge on the ecology of bacterial communities in the sediment of a small, low-gradient stream in South Australia. The quantification of genes involved in the biogeochemical cycling of carbon and nitrogen was used to assess potential impacts on ecosystem functions. The effects of disturbance on bacterial community structure were assessed by PCR-denaturing gradient gel electrophoresis of 16S rRNA genes, and clone library analysis was used to phylogenetically characterize significant shifts. Significant (P < 0.05) shifts in bacterial community structures were associated with alteration of the sediment's physicochemical properties, particularly nutrient loading from the WWTP discharge. The effects were greatest at the sampling location 400 m downstream of the outfall where the stream flow is reduced. This highly affected stretch of sediment contained representatives of the gammaproteobacteria that were absent from less-disturbed sites, including Oceanospirillales and Methylococcaceae. 16S rRNA gene sequences from less-disturbed sites had representatives of the Caulobacteraceae, Sphingomonadaceae, and Nitrospirae which were not represented in samples from disturbed sediment. The diversity was lowest at the reference site; it increased with proximity to the WWTP outfall and declined toward highly disturbed (400 m downstream) sites (P < 0.05). The potential for biological transformations of N varied significantly with the stream sediment location (P < 0.05). The abundance of amoA, narG, and nifH genes increased with the distance downstream of the outfall. These processes are driven by N and C availability, as well as redox conditions. Together these data suggest cause and effect between nutrient loading into the creek, shift in bacterial communities through habitat change, and alteration of capacity for biogeochemical cycling of N.
Collapse
|
21
|
Allen TD, Rutherford SA, Murray S, Sanderson HS, Gardiner F, Kiseleva E, Goldberg MW, Drummond SP. A protocol for isolating Xenopus oocyte nuclear envelope for visualization and characterization by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). Nat Protoc 2008; 2:1166-72. [PMID: 17546011 DOI: 10.1038/nprot.2007.137] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This protocol details methods for the isolation of oocyte nuclear envelopes (NEs) from the African clawed toad Xenopus laevis, immunogold labeling of component proteins and subsequent visualization by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). This procedure involves the initial removal of the ovaries from mature female X. laevis, the dissection of individual oocytes, then the manual isolation of the giant nucleus and subsequent preparation for high-resolution visualization. Unlike light microscopy, and its derivative technologies, electron microscopy enables 3-5 nm resolution of nuclear structures, thereby giving unrivalled opportunities for investigation and immunological characterization in situ of nuclear structures and their structural associations. There are a number of stages where samples can be stored, although we recommend that this protocol take no longer than 2 d. Samples processed for FESEM can be stored for weeks under vacuum, allowing considerable time for image acquisition.
Collapse
Affiliation(s)
- T D Allen
- Paterson Institute for Cancer Research, University of Manchester, Wilmslow Road, Withington, Manchester M20 4BX, UK.
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Schäfer C, Ludwig Y, Shahin V, Kramer A, Carl P, Schillers H, Oberleithner H. Ethanol alters access to the cell nucleus. Pflugers Arch 2006; 453:809-18. [PMID: 17043811 DOI: 10.1007/s00424-006-0165-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Accepted: 08/31/2006] [Indexed: 10/24/2022]
Abstract
Ethanol is the most frequently used drug among humans. We tested the hypothesis whether ethanol, at clinically relevant concentrations modifies, signaling across the nuclear envelope (NE). In cell nuclei isolated from Xenopus oocytes, we measured NE electrical resistance and NE macromolecule permeability 1 to 20 h after addition of ethanol (0.05 to 0.2%). Furthermore, with atomic force microscopy, nuclear pores of the NE were imaged after exposure to ethanol. We found that NE permeability decreased within hours of ethanol exposure. In parallel, nuclei swell and nuclear pores form clusters in the NE. Force measurements on individual nuclear pores indicate that pores found in clusters are stiffer than those found randomly distributed in the NE. Application of a transcription blocker (actinomycin D) or RNase treatment of isolated nuclei in vitro after ethanol exposure prevents the permeability changes. In conclusion, ethanol, at commonly used concentrations, changes NE structure by transcriptional processes in the cell nucleus. Within hours, the NE becomes less permeable for diffusible ions and macromolecules. This could explain altered signaling to and communication with the cell nucleus in the pathophysiology of alcohol abuse.
Collapse
Affiliation(s)
- Claudia Schäfer
- Institute of Physiology II, University of Münster, Münster, Germany
| | | | | | | | | | | | | |
Collapse
|
23
|
Brière C, Xiong TC, Mazars C, Ranjeva R. Autonomous regulation of free Ca2+ concentrations in isolated plant cell nuclei: a mathematical analysis. Cell Calcium 2006; 39:293-303. [PMID: 16473405 DOI: 10.1016/j.ceca.2005.11.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Revised: 11/24/2005] [Accepted: 11/28/2005] [Indexed: 01/14/2023]
Abstract
Experiments performed on nuclei isolated from animal or plant cells have provided evidence that the nucleus generates directly specific nucleoplasmic calcium transients in response to external stimuli. Recent data suggest that isolated plant nuclei might be considered as a closed system where the nuclear concentration of free calcium would be regulated by reversible movements between the nucleoplasm and nuclear stores. We have addressed the relevance of this hypothesis by developing a mathematical approach to simulate nucleoplasmic calcium dynamics generated under various pH and temperature conditions. Here, we show that the experimental results could be explained provided that calcium channels as well as systems transporting calcium are present on the inner nuclear membrane. The putative channels would allow the entry of calcium into the nucleoplasm whereas the elusive transporting system(s) would contribute to replenish the nuclear stores. The simple proposed model is versatile enough to explain and predict autonomous changes in free calcium in the nucleoplasm of isolated plant nuclei.
Collapse
Affiliation(s)
- Christian Brière
- UMR CNRS-UPS 5546, Pôle de Biotechnologie Végétale, Castanet-Tolosan, France
| | | | | | | |
Collapse
|
24
|
Rizzuto R, Pozzan T. Microdomains of intracellular Ca2+: molecular determinants and functional consequences. Physiol Rev 2006; 86:369-408. [PMID: 16371601 DOI: 10.1152/physrev.00004.2005] [Citation(s) in RCA: 876] [Impact Index Per Article: 48.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Calcium ions are ubiquitous and versatile signaling molecules, capable of decoding a variety of extracellular stimuli (hormones, neurotransmitters, growth factors, etc.) into markedly different intracellular actions, ranging from contraction to secretion, from proliferation to cell death. The key to this pleiotropic role is the complex spatiotemporal organization of the [Ca(2+)] rise evoked by extracellular agonists, which allows selected effectors to be recruited and specific actions to be initiated. In this review, we discuss the structural and functional bases that generate the subcellular heterogeneity in cellular Ca(2+) levels at rest and under stimulation. This complex choreography requires the concerted action of many different players; the central role is, of course, that of the calcium ion, with the main supporting characters being all the entities responsible for moving Ca(2+) between different compartments, while the cellular architecture provides a determining framework within which all the players have their exits and their entrances. In particular, we concentrate on the molecular mechanisms that lead to the generation of cytoplasmic Ca(2+) microdomains, focusing on their different subcellular location, mechanism of generation, and functional role.
Collapse
Affiliation(s)
- Rosario Rizzuto
- Department of Experimental and Diagnostic Medicine, and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Ferrara, Italy
| | | |
Collapse
|
25
|
Guinez C, Morelle W, Michalski JC, Lefebvre T. O-GlcNAc glycosylation: a signal for the nuclear transport of cytosolic proteins? Int J Biochem Cell Biol 2005; 37:765-74. [PMID: 15694836 DOI: 10.1016/j.biocel.2004.12.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Indexed: 11/28/2022]
Abstract
Year 2004 marks the 20th anniversary of the discovery of O-linked N-acetylglucosamine (O-GlcNAc) by Gerald W. Hart. Despite interest for O-GlcNAc, the functions played by this single monosaccharide remain poorly understood, though numerous roles have been suggested, among which is the involvement of O-GlcNAc in the nuclear transport of cytosolic proteins. This idea was first sustained by studies on bovine serum albumin that showed that the protein could be actively carried to the nucleus when it was modified with sugars. In this paper, we will review data on this puzzling problem. We will first describe the well-established nuclear localisation signal (NLS)-dependent nuclear transport by presenting the different factors involved, and then, we will examine where and how O-GlcNAc could be involved in nuclear transport. Whereas it has been suggested that O-GlcNAc could interfere at two levels in the nuclear transport both by modifying proteins to be translocated to the nucleus and by modifying the nucleoporins of the nuclear pore complex, according to us, this second idea seems unlikely. Part of this study will also be dedicated to a relatively new concept in the nuclear transport: the role of the 70-kDa heat shock proteins (HSP70). The action of the chaperone in nuclear translocation was put forward 10 years ago, but new findings suggest that this mechanism could be linked to O-GlcNAc glycosylation.
Collapse
Affiliation(s)
- Céline Guinez
- Unité Mixte de Recherches 8576 du CNRS, Glycobiologie Structurale et Fonctionnelle, IFR 118, USTL, Bâtiment C9, 59655 Villeneuve d'Ascq, France
| | | | | | | |
Collapse
|
26
|
Rim JS, Xue B, Gawronska-Kozak B, Kozak LP. Sequestration of thermogenic transcription factors in the cytoplasm during development of brown adipose tissue. J Biol Chem 2004; 279:25916-26. [PMID: 15073176 DOI: 10.1074/jbc.m402102200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcription factors that regulate gene expression during adipogenesis also control the expression of genes of thermogenesis in brown adipose tissue, in particular, the mitochondrial uncoupling protein gene (Ucp1). There is evidence that a plasticity exists among adipocytes in which activation of the Ucp1 gene together with mitochondrial biogenesis can increase the brown adipocyte character of white fat. To understand this process, we have characterized the changes in transcription that occur in interscapular brown adipocytes during development. We have found dramatic reductions in both DNA-binding activity to probes and immunoreactive protein for peroxisome proliferator-activated receptor, retinoid X receptor, CCAAT/enhancer binding protein, and cAMP-response element-binding protein regulatory motifs in nuclear extracts when mice reach adulthood. Exposure of adult mice to the cold, which reactivates Ucp1 expression, leads to a re-accumulation of factors in the nucleus. We propose that transcription factors are sequestered in the cytoplasm as mice age under conditions of reduced thermogenesis. Changes in isoform sub-types for peroxisome proliferator-activated receptor-gamma and cAMP-response element-binding proteins indicate an additional level of control on gene expression during thermogenesis. The increased movement of the RIIbeta protein kinase A regulatory subunit into the nucleus with age suggests a mechanism for regulating the phosphorylation of transcription factors in the nucleus in response to the thermogenic requirements of the animal. Nuclear factor-kappaB has been used as a model to demonstrate that the nuclear localization of transcription factors in brown fat are reduced during post-natal development. Furthermore, it was found by immunofluorescence that adrenergic stimulation of primary adipocyte cultures causes an increase of both the protein kinase A catalytic alpha-subunit and nuclear factor-kappaB into the nucleus.
Collapse
Affiliation(s)
- Jong S Rim
- Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA
| | | | | | | |
Collapse
|
27
|
Imreh G, Maksel D, de Monvel JB, Brandén L, Hallberg E. ER retention may play a role in sorting of the nuclear pore membrane protein POM121. Exp Cell Res 2003; 284:173-84. [PMID: 12651151 DOI: 10.1016/s0014-4827(02)00034-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Integral membrane proteins of the nuclear envelope (NE) are synthesized on the rough endoplasmic reticulum (ER) and following free diffusion in the continuous ER/NE membrane system are targeted to their proper destinations due to interactions of specific domains with other components of the NE. By studying the intracellular distribution and dynamics of a deletion mutant of an integral membrane protein of the nuclear pores, POM121, which lacks the pore-targeting domain, we investigated if ER retention plays a role in sorting of integral membrane proteins to the nuclear envelope. A nascent membrane protein lacking sorting determinants is believed to diffuse laterally in the continuous ER/NE lipid bilayer and expected to follow vesicular traffic to the plasma membrane. The GFP-tagged deletion mutant, POM121(1-129)-GFP, specifically distributed within the ER membrane, but was completely absent from the Golgi compartment and the plasma membrane. Experiments using fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP) demonstrated that despite having very high mobility within the whole ER network (D = 0.41 +/- 0.11 micro m(2)/s) POM121(1-129)-GFP was unable to exit the ER. It was also not detected in post-ER compartments of cells incubated at 15 degrees C. Taken together, these experiments show that amino acids 1-129 of POM121 are able to retain GFP in the ER membrane and suggest that this retention occurs by a direct mechanism rather than by a retrieval mechanism. Our data suggest that ER retention might be important for sorting of POM121 to the nuclear pores.
Collapse
Affiliation(s)
- G Imreh
- Södertörns Högskola (University College), S-141 89, Huddinge, Sweden
| | | | | | | | | |
Collapse
|
28
|
Moore-Nichols D, Arnott A, Dunn RC. Regulation of nuclear pore complex conformation by IP(3) receptor activation. Biophys J 2002; 83:1421-8. [PMID: 12202368 PMCID: PMC1302241 DOI: 10.1016/s0006-3495(02)73913-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
In recent years, both the molecular architecture and functional dynamics of nuclear pore complexes (NPCs) have been revealed with increasing detail. These large, supramolecular assemblages of proteins form channels that span the nuclear envelope of cells, acting as crucial regulators of nuclear import and export. From the cytoplasmic face of the nuclear envelope, nuclear pore complexes exhibit an eightfold symmetric ring structure encompassing a central lumen. The lumen often appears occupied by an additional structure alternatively referred to as the central granule, nuclear transport complex, or nuclear plug. Previous studies have suggested that the central granule may play a role in mediating calcium-dependent regulation of diffusion across the nuclear envelope for intermediate sized molecules (10-40 kDa). Using atomic force microscopy to measure the surface topography of chemically fixed Xenopus laevis oocyte nuclear envelopes, we present measurements of the relative position of the central granule within the NPC lumen under a variety of conditions known to modify nuclear Ca(2+) stores. These measurements reveal a large, approximately 9-nm displacement of the central granule toward the cytoplasmic face of the nuclear envelope under calcium depleting conditions. Additionally, activation of nuclear inositol triphosphate (IP(3)) receptors by the specific agonist, adenophostin A, results in a concentration-dependent displacement of central granule position with an EC(50) of ~1.2 nM. The displacement of the central granule within the NPC is observed on both the cytoplasmic and nucleoplasmic faces of the nuclear envelope. The displacement is blocked upon treatment with xestospongin C, a specific inhibitor of IP(3) receptor activation. These results extend previous models of NPC conformational dynamics linking central granule position to depletion of IP(3) sensitive nuclear envelope calcium stores.
Collapse
|
29
|
Meyer G, Gicklhorn D, Strive T, Radsak K, Eickmann M. A three-residue signal confers localization of a reporter protein in the inner nuclear membrane. Biochem Biophys Res Commun 2002; 291:966-71. [PMID: 11866460 DOI: 10.1006/bbrc.2002.6563] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
By alignment to the carboxy-terminal-deduced aa sequence of human cytomegalovirus glycoprotein B (gB), conserved hexameric aa motifs with putative function for localization in the inner nuclear membrane (INM) were identified in the nucleoplasmic tails of herpes simplex virus type 1 gB and of the cellular lamin B receptor. Fusion of the respective hexamers to CD8 as a reporter redirected transport of the chimeras into the INM, suggesting their functioning as modular signal motifs. Consecutive experiments showed that the three-residue motif RxR represents a consensus sequence which is sufficient for localization of the CD8 reporter in the INM.
Collapse
Affiliation(s)
- Grit Meyer
- Institut für Virologie, Philipps-Universität, Robert-Koch-Strasse 17, DE-35037 Marburg, Germany
| | | | | | | | | |
Collapse
|
30
|
Beaudouin J, Gerlich D, Daigle N, Eils R, Ellenberg J. Nuclear envelope breakdown proceeds by microtubule-induced tearing of the lamina. Cell 2002; 108:83-96. [PMID: 11792323 DOI: 10.1016/s0092-8674(01)00627-4] [Citation(s) in RCA: 340] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mechanism of nuclear envelope breakdown (NEBD) was investigated in live cells. Early spindle microtubules caused folds and invaginations in the NE up to one hour prior to NEBD, creating mechanical tension in the nuclear lamina. The first gap in the NE appeared before lamin B depolymerization, at the site of maximal tension, by a tearing mechanism. Gap formation relaxed this tension and dramatically accelerated the rate of chromosome condensation. The hole produced in the NE then rapidly expanded over the nuclear surface. NE fragments remaining on chromosomes were removed toward the centrosomes in a microtubule-dependent manner, suggesting a mechanism mediated by a minus-end-directed motor.
Collapse
Affiliation(s)
- Joël Beaudouin
- Gene Expression and Cell Biology/Biophysics Programmes, European Molecular Biology Laboratory, D-69117. Heidelberg, Germany
| | | | | | | | | |
Collapse
|
31
|
Baumann O, Walz B. Endoplasmic reticulum of animal cells and its organization into structural and functional domains. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 205:149-214. [PMID: 11336391 DOI: 10.1016/s0074-7696(01)05004-5] [Citation(s) in RCA: 335] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
The endoplasmic reticulum (ER) in animal cells is an extensive, morphologically continuous network of membrane tubules and flattened cisternae. The ER is a multifunctional organelle; the synthesis of membrane lipids, membrane and secretory proteins, and the regulation of intracellular calcium are prominent among its array of functions. Many of these functions are not homogeneously distributed throughout the ER but rather are confined to distinct ER subregions or domains. This review describes the structural and functional organization of the ER and highlights the dynamic properties of the ER network and the mechanisms that support the positioning of ER membranes within the cell. Furthermore, we outline processes involved in the establishment and maintenance of an anisotropic distribution of ER-resident proteins and, thus, in the organization of the ER into functionally and morphologically different subregions.
Collapse
Affiliation(s)
- O Baumann
- Institut für Biochemie und Biologie, Zoophysiologie, Universität Potsdam, Germany
| | | |
Collapse
|
32
|
Kiseleva E, Rutherford S, Cotter LM, Allen TD, Goldberg MW. Steps of nuclear pore complex disassembly and reassembly during mitosis in earlyDrosophilaembryos. J Cell Sci 2001; 114:3607-18. [PMID: 11707513 DOI: 10.1242/jcs.114.20.3607] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms of nuclear pore complex (NPC) assembly and disassembly during mitosis in vivo are not well defined. To address this and to identify the steps of the NPC disassembly and assembly, we investigated Drosophila embryo nuclear structure at the syncytial stage of early development using field emission scanning electron microscopy (FESEM), a high resolution surface imaging technique, and transmission electron microscopy. Nuclear division in syncytial embryos is characterized by semi-closed mitosis, during which the nuclear membranes are ruptured only at the polar regions and are arranged into an inner double membrane surrounded by an additional ‘spindle envelope’. FESEM analysis of the steps of this process as viewed on the surface of the dividing nucleus confirm our previous in vitro model for the assembly of the NPCs via a series of structural intermediates, showing for the first time a temporal progression from one intermediate to the next. Nascent NPCs initially appear to form at the site of fusion between the mitotic nuclear envelope and the overlying spindle membrane. A model for NPC disassembly is offered that starts with the release of the central transporter and the removal of the cytoplasmic ring subunits before the star ring.
Collapse
Affiliation(s)
- E Kiseleva
- CRC Department of Structural Cell Biology, Paterson Institute for Cancer Research, Christie Hospital, Wilmslow Road, Manchester, M20 9BX, UK
| | | | | | | | | |
Collapse
|
33
|
Klink DT, Glick MC, Scanlin TF. Gene therapy of cystic fibrosis (CF) airways: a review emphasizing targeting with lactose. Glycoconj J 2001; 18:731-40. [PMID: 12386459 DOI: 10.1023/a:1020879524587] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cystic fibrosis is a disease for which a number of Phase I clinical trials of gene therapy have been initiated. Several factors account for the high level of interest in a gene therapy approach to this disease. CF is the most common lethal inherited disease in Caucasian populations. The lung, the organ that is predominantly responsible for the morbidity and mortality in CF patients, is accessible by a non-invasive method, the inhalation of aerosols. The vectors employed in the Phase I trials have included recombinant adenoviruses, adeno-associated viruses and cationic lipids. While there have been some positive results, the success of the vectors until now has been limited by either immunogenicity or low efficiency. A more fundamental obstacle has been the absence of appropriate receptors on the apical surface of airway epithelial cells. Molecular conjugates with carbohydrate substitution to provide targeting offer several potential advantages. Lactosylated polylysine in which 40% of the lysines have been substituted with lactose has been shown to provide a high efficiency of transfection in primary cultures of CF airway epithelial cells. Other important features include a relatively low immunogenicity and cytotoxicity. Most importantly, the lactosylated polylysine was demonstrated to give nuclear localization in CF airway epithelial cells. Until now, most non-viral vectors did not have the capability to provide nuclear localization. These unique qualities provided by the lactosylation of non-viral vectors, such as polylysine may help to advance the development of molecular conjugates sufficiently to warrant their use in future clinical trials for the gene therapy of inherited diseases of the lung.
Collapse
Affiliation(s)
- D T Klink
- The Cystic Fibrosis Center and Department of Pediatrics, University of Pennsylvania, School of Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | | | | |
Collapse
|
34
|
Daigle N, Beaudouin J, Hartnell L, Imreh G, Hallberg E, Lippincott-Schwartz J, Ellenberg J. Nuclear pore complexes form immobile networks and have a very low turnover in live mammalian cells. J Cell Biol 2001; 154:71-84. [PMID: 11448991 PMCID: PMC2196857 DOI: 10.1083/jcb.200101089] [Citation(s) in RCA: 305] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2001] [Revised: 05/25/2001] [Accepted: 05/31/2001] [Indexed: 11/22/2022] Open
Abstract
The nuclear pore complex (NPC) and its relationship to the nuclear envelope (NE) was characterized in living cells using POM121-green fluorescent protein (GFP) and GFP-Nup153, and GFP-lamin B1. No independent movement of single pore complexes was found within the plane of the NE in interphase. Only large arrays of NPCs moved slowly and synchronously during global changes in nuclear shape, strongly suggesting mechanical connections which form an NPC network. The nuclear lamina exhibited identical movements. NPC turnover measured by fluorescence recovery after photobleaching of POM121 was less than once per cell cycle. Nup153 association with NPCs was dynamic and turnover of this nucleoporin was three orders of magnitude faster. Overexpression of both nucleoporins induced the formation of annulate lamellae (AL) in the endoplasmic reticulum (ER). Turnover of AL pore complexes was much higher than in the NE (once every 2.5 min). During mitosis, POM121 and Nup153 were completely dispersed and mobile in the ER (POM121) or cytosol (Nup153) in metaphase, and rapidly redistributed to an immobilized pool around chromatin in late anaphase. Assembly and immobilization of both nucleoporins occurred before detectable recruitment of lamin B1, which is thus unlikely to mediate initiation of NPC assembly at the end of mitosis.
Collapse
Affiliation(s)
- N Daigle
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | | | | | | | | | | | | |
Collapse
|
35
|
Kapon R, Nevo R, Shuhmaher N, Shahar D, Reich Z. From Single Complexes to Single Molecules Using Tapping Mode Scanning Force Microscopy and Capacitance-Based Motion Detection. ACTA ACUST UNITED AC 2001. [DOI: 10.1002/1438-5171(200107)2:2<85::aid-simo85>3.0.co;2-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
36
|
Klink DT, Chao S, Glick MC, Scanlin TF. Nuclear translocation of lactosylated poly-L-lysine/cDNA complex in cystic fibrosis airway epithelial cells. Mol Ther 2001; 3:831-41. [PMID: 11407896 DOI: 10.1006/mthe.2001.0332] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Poly-l-lysine, with 40% of its amino groups substituted with lactose, is an effective vector to transfer the CFTR gene into CF airway epithelial cells and correct the chloride channel dysfunction. The intracellular fate of the lactosylated poly-l-lysine/cDNA complex was studied using confocal microscopy. In the presence of chloroquine the complex remained intact during internalization, intracellular transport, and, most importantly, transport into the nucleus. When cells were transfected in the presence of agents that enhance transfection efficiency such as E5CA peptide, a fusogenic peptide, or glycerol a similar fate of the lactosylated poly-l-lysine/cDNA complex was seen. However, when these agents were omitted from the transfection medium, the complex remained in the perinuclear region. Uncomplexed lactosylated poly-l-lysine reached the nucleus efficiently. In contrast mannosylated poly-l-lysine or unsubstituted poly-l-lysine complexed to plasmid did not. Therefore the nuclear accumulation of the complex may be attributed to the substitution of poly-l-lysine with lactose. It is hypothesized that the lactose residues provide for nuclear localization by means of targeting a potential lectin-like protein with galactose/lactose specificity. This mechanism may be responsible for the nuclear internalization of the complex.
Collapse
Affiliation(s)
- D T Klink
- The Cystic Fibrosis Center, Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | | | | | | |
Collapse
|
37
|
Xie CX, Ozawa H, Yang YM, Kawata M. Immunohistochemical study of nucleoporin p62 in the hippocampus and hypothalamus of the rat brain. Neuroreport 2000; 11:2965-7. [PMID: 11006975 DOI: 10.1097/00001756-200009110-00027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We immunohistochemically studied the distribution of nucleoporin p62 in the hippocampus and hypothalamus of rat brain. Previous reports have shown the presence of p62-immunoreactivity (ir) in the nuclear rim in the non-neuronal cells, but the present study showed that of p62-ir within the nucleus in addition to the nuclear rim in the neuronal cells of the hippocampus and hypothalamic nuclei; in these areas the glucocorticoid receptor (GR) undergoes nucleocytoplasmic translocation determined by ligand. We analyzed the expression of p62-ir after adrenalectomy (ADX). ADX changed the localization of GR-ir from the nucleus to the cytoplasm, but did not change the localization or immunoreactivity of p62, suggesting that nucleoporin p62 is stable regardless of intracellular signal transduction between the cytoplasm and the nucleus.
Collapse
Affiliation(s)
- C X Xie
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Japan
| | | | | | | |
Collapse
|
38
|
Affiliation(s)
- P Collas
- Institute of Medical Biochemistry, University of Oslo, Norway
| | | |
Collapse
|
39
|
Allen TD, Cronshaw JM, Bagley S, Kiseleva E, Goldberg MW. The nuclear pore complex: mediator of translocation between nucleus and cytoplasm. J Cell Sci 2000; 113 ( Pt 10):1651-9. [PMID: 10769196 DOI: 10.1242/jcs.113.10.1651] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enclosure of nuclear contents in eukaryotes means that cells require sites in the boundary that mediate exchange of material between nucleus and cytoplasm. These sites, termed nuclear pore complexes (NPCs), number 100–200 in yeast, a few thousand in mammalian cells and approximately 50 million in the giant nuclei of amphibian oocytes. NPCs are large (125 MDa) macromolecular complexes that comprise 50–100 different proteins in vertebrates. In spite of their size and complex structure, NPCs undergo complete breakdown and reformation at cell division. Transport through NPCs can be rapid (estimated at several hundred molecules/pore/second) and accommodates both passive diffusion of relatively small molecules, and active transport of complexes up to several megadaltons in molecular mass. Each pore can facilitate both import and export. The two processes apparently involve multiple pathways for different cargoes, and their transport signals, transport receptors and adapters, and the molecules (and their regulators) that underpin the transport mechanisms. Over the past few years there has been an increasing interest in the pore complex: structural studies have been followed by elucidation of the biochemical aspects of nuclear import, and subsequent investigations into nuclear export. The current challenge is to understand the interactions between the structural elements of the pore complex and the mechanisms that drive the physical processes of translocation through it.
Collapse
Affiliation(s)
- T D Allen
- CRC Structural Cell Biology Group, Paterson Institute, Christie Hospital, Manchester, M20 4BX, UK
| | | | | | | | | |
Collapse
|
40
|
Meyer GA, Radsak KD. Identification of a novel signal sequence that targets transmembrane proteins to the nuclear envelope inner membrane. J Biol Chem 2000; 275:3857-66. [PMID: 10660537 DOI: 10.1074/jbc.275.6.3857] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Herpesvirus maturation requires translocation of glycoprotein B homologue from the endoplasmic reticulum to the inner nuclear membrane. Glycoprotein B of human cytomegalovirus was used in this context as a model protein. To identify a specific signal sequence within human cytomegalovirus glycoprotein B acting in a modular fashion, coding sequences were recombined with reporter proteins. Immunofluorescence and cell fractionation demonstrated that a short sequence element within the cytoplasmic tail of human cytomegalovirus glycoprotein B was sufficient to translocate the membrane protein CD8 to the inner nuclear membrane. This carboxyl-terminal sequence had no detectable nuclear localization signal activity for soluble beta-Galactosidase and could not be substituted by the nuclear localization signal of SV40 T antigen. For glycoprotein B of herpes simplex virus, a carboxyl-terminal element with comparable properties was found. Further experiments showed that the amino acid sequence DRLRHR of human cytomegalovirus glycoprotein B (amino acids 885-890) was sufficient for nuclear envelope translocation. Single residue mutations revealed that the arginine residues in positions 4 and 6 of the DRLRHR sequence were essential for its function. These results support the view that transmembrane protein transport to the inner nuclear membrane is controlled by a mechanism different from that of soluble proteins.
Collapse
Affiliation(s)
- G A Meyer
- Institut für Virologie der Philipps-Universität, Robert-Koch-Strasse 17, 35037 Marburg, Germany
| | | |
Collapse
|
41
|
Kosova B, Panté N, Rollenhagen C, Podtelejnikov A, Mann M, Aebi U, Hurt E. Mlp2p, a component of nuclear pore attached intranuclear filaments, associates with nic96p. J Biol Chem 2000; 275:343-50. [PMID: 10617624 DOI: 10.1074/jbc.275.1.343] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A fraction of the yeast nucleoporin Nic96p is localized at the terminal ring of the nuclear basket. When Nic96p was affinity purified from glutaraldehyde-treated spheroplasts, it was found to be associated with Mlp2p. Mlp2p, together with Mlp1p, are the yeast Tpr homologues, which form the nuclear pore-attached intranuclear filaments (Strambio-de-Castillia, C., Blobel, G., and Rout, M. P. (1999) J. Cell Biol. 144, 839-855). Double disruption mutants of MLP1 and MLP2 are viable and apparently not impaired in nucleocytoplasmic transport. However, overproduction of MLP1 causes nuclear accumulation of poly(A)(+) RNA in a chromatin-free area of the nucleus.
Collapse
Affiliation(s)
- B Kosova
- BZH, Biochemie-Zentrum Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | | | | | | | | | | | | |
Collapse
|
42
|
Yoneda Y, Hieda M, Nagoshi E, Miyamoto Y. Nucleocytoplasmic protein transport and recycling of Ran. Cell Struct Funct 1999; 24:425-33. [PMID: 10698256 DOI: 10.1247/csf.24.425] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The active transport of proteins into and out of the nucleus is mediated by specific signals, the nuclear localization signal (NLS) and nuclear export signal (NES), respectively. The best characterized NLS is that of the SV40 large T antigen, which contains a cluster of basic amino acids. The NESs were first identified in the protein kinase inhibitor (PKI) and HIV Rev protein, which are rich in leucine residues. The SV40 T-NLS containing transport substrates are carried into the nucleus by an importin alpha/beta heterodimer. Importin alpha recognizes the NLS and acts as an adapter between the NLS and importin beta, whereas importin beta interacts with importin alpha bound to the NLS, and acts as a carrier of the NLS/importin alpha/beta trimer. It is generally thought that importin alpha and beta are part of a large protein family. The leucine rich NES-containing proteins are exported from the nucleus by one of the importin beta family molecules, CRM1/exportin 1. A Ras-like small GTPase Ran plays a crucial role in both import/export pathways and determines the directionality of nuclear transport. It has recently been demonstrated in living cells that Ran actually shuttles between the nucleus and the cytoplasm and that the recycling of Ran is essential for the nuclear transport. Furthermore, it has been shown that nuclear transport factor 2 (NTF2) mediates the nuclear import of RanGDP. This review largely focuses on the issue concerning the functional divergence of importin alpha family molecules and the role of Ran in nucleocytoplasmic protein transport.
Collapse
Affiliation(s)
- Y Yoneda
- Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Japan
| | | | | | | |
Collapse
|
43
|
Kubitscheck U, Kues T, Peters R. Visualization of nuclear pore complex and its distribution by confocal laser scanning microscopy. Methods Enzymol 1999; 307:207-30. [PMID: 10506976 DOI: 10.1016/s0076-6879(99)07015-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- U Kubitscheck
- Institut für Medizinische Physik und Biophysik, Universität Münster, Germany
| | | | | |
Collapse
|
44
|
Bodoor K, Shaikh S, Enarson P, Chowdhury S, Salina D, Raharjo WH, Burke B. Function and assembly of nuclear pore complex proteins. Biochem Cell Biol 1999. [DOI: 10.1139/o99-038] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nuclear pore complexes (NPCs) are extremely elaborate structures that mediate the bidirectional movement of macromolecules between the nucleus and cytoplasm. The current view of NPC organization features a massive symmetrical framework that is embedded in the double membranes of the nuclear envelope. It embraces a central channel of as yet ill-defined structure but which may accommodate particles with diameters up to 26 nm provided that they bear specific import/export signals. Attached to both faces of the central framework are peripheral structures, short cytoplasmic filaments, and a nuclear basket assembly, which interact with molecules transiting the NPC. The mechanisms of assembly and the nature of NPC structural intermediates are still poorly understood. However, mutagenesis and expression studies have revealed discrete sequences within certain NPC proteins that are necessary and sufficient for their appropriate targeting. In addition, some details are emerging from observations on cells undergoing mitosis where the nuclear envelope is disassembled and its components, including NPC subunits, are dispersed throughout the mitotic cytoplasm. At the end of mitosis, all of these components are reutilized to form nuclear envelopes in the two daughter cells. To date, it has been possible to define a time course of postmitotic assembly for a group of NPC components (CAN/Nup214, Nup153, POM121, p62 and Tpr) relative to the integral inner nuclear membrane protein LAP2 and the NPC membrane glycoprotein gp210. Nup153, a dynamic component of the nuclear basket, associates with chromatin towards the end of anaphase coincident with, although independent of, the inner nuclear membrane protein, LAP2. Assembly of the remaining proteins follows that of the nuclear membranes and occurs in the sequence POM121, p62, CAN/Nup214 and gp210/Tpr. Since p62 remains as a complex with three other NPC proteins (p58, p54, p45) during mitosis, and CAN/Nup214 maintains a similar interaction with its partner, Nup84, the relative timing of assembly of these additional four proteins may also be inferred. These observations suggest that there is a sequential association of NPC proteins with chromosomes during nuclear envelope reformation and the recruitment of at least eight of these precedes that of gp210. These findings support a model in which it is POM121 rather than gp210 that defines initial membrane-associated NPC assembly intermediates and which may therefore represent an essential component of the central framework of the NPC. Key words: nuclear pore complex, nucleoporin, mitosis, nuclear transport
Collapse
|
45
|
Bodoor K, Shaikh S, Salina D, Raharjo WH, Bastos R, Lohka M, Burke B. Sequential recruitment of NPC proteins to the nuclear periphery at the end of mitosis. J Cell Sci 1999; 112 ( Pt 13):2253-64. [PMID: 10362555 DOI: 10.1242/jcs.112.13.2253] [Citation(s) in RCA: 154] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nuclear pore complexes (NPCs) are extremely elaborate structures that mediate the bidirectional movement of macromolecules between the nucleus and cytoplasm. With a mass of about 125 MDa, NPCs are thought to be composed of 50 or more distinct protein subunits, each present in multiple copies. During mitosis in higher cells the nuclear envelope is disassembled and its components, including NPC subunits, are dispersed throughout the mitotic cytoplasm. At the end of mitosis, all of these components are reutilized. Using both conventional and digital confocal immunofluorescence microscopy we have been able to define a time course of post-mitotic assembly for a group of NPC components (CAN/Nup214, Nup153, POM121, p62 and Tpr) relative to the integral nuclear membrane protein LAP2 and the NPC membrane glycoprotein gp210. Nup153, a component of the nuclear basket, associates with chromatin towards the end of anaphase, in parallel with the inner nuclear membrane protein, LAP2. However, immunogold labeling suggests that the initial Nup153 chromatin association is membrane-independent. Assembly of the remaining proteins follows that of the nuclear membranes and occurs in the sequence POM121, p62, CAN/Nup214 and gp210/Tpr. Since p62 remains as a complex with three other NPC proteins (p58, 54, 45) during mitosis and CAN/Nup214 maintains a similar interaction with its partner, Nup84, the relative timing of assembly of these additional four proteins may also be inferred. These observations suggest that there is a sequential association of NPC proteins with chromosomes during nuclear envelope reformation and the recruitment of at least eight of these precedes that of gp210. These findings support a model in which it is POM121 rather than gp210 that defines initial membrane-associated NPC assembly intermediates.
Collapse
Affiliation(s)
- K Bodoor
- The Cancer Biology Research Group, The University of Calgary, Faculty of Medicine, Calgary AB, Canada T2N 4N1
| | | | | | | | | | | | | |
Collapse
|
46
|
Abstract
By bridging the double membrane separating the cell nucleus and cytoplasm, nuclear pore complexes (NPCs) are crucial pathways for the exchange of ions, proteins, and RNA between these two cellular compartments. A structure in the central lumen of the NPC, called the nuclear transport protein, central granule, or nuclear plug, appeared to gate diffusion of intermediate-sized molecules (10-40 kDa) across the nuclear membranes. Visualization of the NPC required drying and fixation of the specimen for electron and atomic force microscopy (AFM), a requirement that has raised doubts about the physiological relevance of the observation. Here we present AFM images of the outer nuclear membranes and NPCs of Xenopus laevis oocytes under more physiological conditions. Measured under a variety of Ca2+ depletion conditions, the central granule appeared to occupy and occlude the lumen of the pore in >80% of NPCs compared to <10% in controls. In a few instances images were obtained of the same NPCs as the solution was changed from control saline to store depletion conditions, and finally to store repletion conditions. We conclude that the central lumen of the nuclear pore complex undergoes a conformational change in response to depletion of nuclear cisternal Ca2+ levels.
Collapse
Affiliation(s)
- H Wang
- Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115 USA
| | | |
Collapse
|
47
|
Ullman KS, Shah S, Powers MA, Forbes DJ. The nucleoporin nup153 plays a critical role in multiple types of nuclear export. Mol Biol Cell 1999; 10:649-64. [PMID: 10069809 PMCID: PMC25193 DOI: 10.1091/mbc.10.3.649] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The fundamental process of nucleocytoplasmic transport takes place through the nuclear pore. Peripheral pore structures are presumably poised to interact with transport receptors and their cargo as these receptor complexes first encounter the pore. One such peripheral structure likely to play an important role in nuclear export is the basket structure located on the nuclear side of the pore. At present, Nup153 is the only nucleoporin known to localize to the surface of this basket, suggesting that Nup153 is potentially one of the first pore components an RNA or protein encounters during export. In this study, anti-Nup153 antibodies were used to probe the role of Nup153 in nuclear export in Xenopus oocytes. We found that Nup153 antibodies block three major classes of RNA export, that of snRNA, mRNA, and 5S rRNA. Nup153 antibodies also block the NES protein export pathway, specifically the export of the HIV Rev protein, as well as Rev-dependent RNA export. Not all export was blocked; Nup153 antibodies did not impede the export of tRNA or the recycling of importin beta to the cytoplasm. The specific antibodies used here also did not affect nuclear import, whether mediated by importin alpha/beta or by transportin. Overall, the results indicate that Nup153 is crucial to multiple classes of RNA and protein export, being involved at a vital juncture point in their export pathways. This juncture point appears to be one that is bypassed by tRNA during its export. We asked whether a physical interaction between RNA and Nup153 could be observed, using homoribopolymers as sequence-independent probes for interaction. Nup153, unlike four other nucleoporins including Nup98, associated strongly with poly(G) and significantly with poly(U). Thus, Nup153 is unique among the nucleoporins tested in its ability to interact with RNA and must do so either directly or indirectly through an adaptor protein. These results suggest a unique mechanistic role for Nup153 in the export of multiple cargos.
Collapse
Affiliation(s)
- K S Ullman
- Department of Biology, University of California at San Diego, La Jolla, California 92093-0347, USA.
| | | | | | | |
Collapse
|
48
|
Bangs P, Burke B, Powers C, Craig R, Purohit A, Doxsey S. Functional analysis of Tpr: identification of nuclear pore complex association and nuclear localization domains and a role in mRNA export. J Cell Biol 1998; 143:1801-12. [PMID: 9864356 PMCID: PMC2175216 DOI: 10.1083/jcb.143.7.1801] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/1998] [Revised: 11/24/1998] [Indexed: 12/02/2022] Open
Abstract
Tpr is a 270-kD coiled-coil protein localized to intranuclear filaments of the nuclear pore complex (NPC). The mechanism by which Tpr contributes to the structure and function of the nuclear pore is currently unknown. To gain insight into Tpr function, we expressed the full-length protein and several subdomains in mammalian cell lines and examined their effects on nuclear pore function. Through this analysis, we identified an NH2-terminal domain that was sufficient for association with the nucleoplasmic aspect of the NPC. In addition, we unexpectedly found that the acidic COOH terminus was efficiently transported into the nuclear interior, an event that was apparently mediated by a putative nuclear localization sequence. Ectopic expression of the full-length Tpr caused a dramatic accumulation of poly(A)+ RNA within the nucleus. Similar results were observed with domains that localized to the NPC and the nuclear interior. In contrast, expression of these proteins did not appear to affect nuclear import. These data are consistent with a model in which Tpr is tethered to intranuclear filaments of the NPC by its coiled coil domain leaving the acidic COOH terminus free to interact with soluble transport factors and mediate export of macromolecules from the nucleus.
Collapse
Affiliation(s)
- P Bangs
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | | | | | | | | | | |
Collapse
|
49
|
Siniossoglou S, Santos-Rosa H, Rappsilber J, Mann M, Hurt E. A novel complex of membrane proteins required for formation of a spherical nucleus. EMBO J 1998; 17:6449-64. [PMID: 9822591 PMCID: PMC1170993 DOI: 10.1093/emboj/17.22.6449] [Citation(s) in RCA: 182] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Two membrane proteins were identified through their genetic interaction with the nucleoporin Nup84p and shown to participate in nuclear envelope morphogenesis in yeast. One component is a known sporulation factor Spo7p, and the other, Nem1p, a novel protein whose C-terminal domain is conserved during eukaryotic evolution. Spo7p and Nem1p localize to the nuclear/ER membrane and behave biochemically as integral membrane proteins. Nem1p binds to Spo7p via its conserved C-terminal domain. Although cells without Spo7p or Nem1p are viable, they exhibit a drastically altered nuclear morphology with long, pore-containing double nuclear membrane extensions. These protrusions emanate from a core nucleus which contains the DNA, and penetrate deeply into the cytoplasm. Interestingly, not only Spo7(-) and Nem1(-), but also several nucleoporin mutants are defective in sporulation. Thus, Spo7p and Nem1p, which exhibit a strong genetic link to nucleoporins of the Nup84p complex, fulfil an essential role in formation of a spherical nucleus and meiotic division.
Collapse
Affiliation(s)
- S Siniossoglou
- BZH, Biochemie-Zentrum Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | | | | | | | | |
Collapse
|
50
|
Bucci M, Wente SR. A novel fluorescence-based genetic strategy identifies mutants of Saccharomyces cerevisiae defective for nuclear pore complex assembly. Mol Biol Cell 1998; 9:2439-61. [PMID: 9725905 PMCID: PMC25512 DOI: 10.1091/mbc.9.9.2439] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Nuclear pore complexes (NPCs) are large proteinaceous portals for exchanging macromolecules between the nucleus and the cytoplasm. Revealing how this transport apparatus is assembled will be critical for understanding the nuclear transport mechanism. To address this issue and to identify factors that regulate NPC formation and dynamics, a novel fluorescence-based strategy was used. This approach is based on the functional tagging of NPC proteins with the green fluorescent protein (GFP), and the hypothesis that NPC assembly mutants will have distinct GFP-NPC signals as compared with wild-type (wt) cells. By fluorescence-activated cell sorting for cells with low GFP signal from a population of mutagenized cells expressing GFP-Nup49p, three complementation groups were identified: two correspond to mutant nup120 and gle2 alleles that result in clusters of NPCs. Interestingly, a third group was a novel temperature-sensitive allele of nup57. The lowered GFP-Nup49p incorporation in the nup57-E17 cells resulted in a decreased fluorescence level, which was due in part to a sharply diminished interaction between the carboxy-terminal truncated nup57pE17 and wt Nup49p. Interestingly, the nup57-E17 mutant also affected the incorporation of a specific subset of other nucleoporins into the NPC. Decreased levels of NPC-associated Nsp1p and Nup116p were observed. In contrast, the localizations of Nic96p, Nup82p, Nup159p, Nup145p, and Pom152p were not markedly diminished. Coincidentally, nuclear import capacity was inhibited. Taken together, the identification of such mutants with specific perturbations of NPC structure validates this fluorescence-based strategy as a powerful approach for providing insight into the mechanism of NPC biogenesis.
Collapse
Affiliation(s)
- M Bucci
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | |
Collapse
|