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Yang Q, Wang W. The Nuclear Translocation of Heme Oxygenase-1 in Human Diseases. Front Cell Dev Biol 2022; 10:890186. [PMID: 35846361 PMCID: PMC9277552 DOI: 10.3389/fcell.2022.890186] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 06/10/2022] [Indexed: 12/30/2022] Open
Abstract
Heme oxygenase-1 (HO-1) is a rate-limiting enzyme in the degradation of heme to generate carbon monoxide (CO), free iron and biliverdin, which could then be converted to bilirubin by biliverdin reductase. HO-1 exhibits cytoprotective effects of anti-apoptosis, anti-oxidation, and anti-inflammation via these byproducts generated during the above process. In the last few years, despite the canonical function of HO-1 and possible biological significance of its byproducts, a noncanonical function, through which HO-1 exhibits functions in diseases independent of its enzyme activity, also has been reported. In this review, the noncanonical functions of HO-1 and its translocation in other subcellular compartments are summarized. More importantly, we emphasize the critical role of HO-1 nuclear translocation in human diseases. Intriguingly, this translocation was linked to tumorigenesis and tumor progression in lung, prostate, head, and neck squamous cell carcinomas and chronic myeloid leukemia. Given the importance of HO-1 nuclear translocation in human diseases, nuclear HO-1 as a novel target might be attractive for the prevention and treatment of human diseases.
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Affiliation(s)
- Qing Yang
- Department of Breast Surgery, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
| | - Wenqian Wang
- Department of Plastic Surgery, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- *Correspondence: Wenqian Wang,
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2
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Ogawa Y, Imamoto N. Methods to separate nuclear soluble fractions reflecting localizations in living cells. iScience 2021; 24:103503. [PMID: 34934922 DOI: 10.1016/j.isci.2021.103503] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 08/15/2021] [Accepted: 11/22/2021] [Indexed: 12/16/2022] Open
Abstract
To understand various intranuclear functions, it is important to know when, what, and how proteins enter the nucleus. Although many methods and commercial kits for nuclear fractionation have been developed, there are still no methods for obtaining a complete nuclear proteome. Soluble nuclear proteins are often lost during fractionation. We developed remarkably improved methods to obtain nuclear soluble fractions by optimizing the conditions of selective permeabilization of the plasma membrane. As a result, 10 million cells could be separated into the cytoplasmic and nuclear soluble fractions more precisely in a 1.5-mL test tube. Moreover, the addition of an inhibitor to prevent leakage from the nucleus retained small proteins in the nucleus. Because of the simple protocols and easy application for multiple samples, our methods are expected to be applied to various studies on spatiotemporal changes of dynamic nuclear proteins, such as signal transduction.
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Affiliation(s)
- Yutaka Ogawa
- Cellular Dynamics Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Naoko Imamoto
- Cellular Dynamics Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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3
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Chen S, Wang X, Nisar MF, Lin M, Zhong JL. Heme Oxygenases: Cellular Multifunctional and Protective Molecules against UV-Induced Oxidative Stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:5416728. [PMID: 31885801 PMCID: PMC6907065 DOI: 10.1155/2019/5416728] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 10/29/2019] [Indexed: 12/20/2022]
Abstract
Ultraviolet (UV) irradiation can be considered as a double-edged sword: not only is it a crucial environmental factor that can cause skin-related disorders but it can also be used for phototherapy of skin diseases. Inducible heme oxygenase-1 (HO-1) in response to a variety of stimuli, including UV exposure, is vital to maintain cell homeostasis. Heme oxygenase-2 (HO-2), another member of the heme oxygenase family, is constitutively expressed. In this review, we discuss how heme oxygenase (HO), a vital rate-limiting enzyme, participates in heme catabolism and cytoprotection. Phylogenetic analysis showed that there may exist a functional differentiation between HO-1 and HO-2 during evolution. Furthermore, depending on functions in immunomodulation and antioxidation, HO-1 participates in disease progression, especially in pathogenesis of skin diseases, such as vitiligo and psoriasis. To further investigate the particular role of HO-1 in diseases, we summarized the profile of the HO enzyme system and its related signaling pathways, such as Nrf2 and endoplasmic reticulum crucial signaling, both known to regulate HO-1 expression. Furthermore, we report on a C-terminal truncation of HO-1, which is generally considered as a signal molecule. Also, a newly identified alternative splice isoform of HO-1 not only provides us a novel perspective on comprehensive HO-1 alternative splicing but also offers us a basis to clarify the relationship between HO-1 transcripts and oxidative diseases. To conclude, the HO system is not only involved in heme catabolism but also involved in biological processes related to the pathogenesis of certain diseases, even though the mechanism of disease progression still remains sketchy. Further understanding the role of the HO system and its relationship to UV is helpful for revealing the HO-related signaling networks and the pathogenesis of many diseases.
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Affiliation(s)
- ShiDa Chen
- The Base of “111 Project” for Biomechanics & Tissue Repair Engineering; Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China
| | - XiaoYu Wang
- The Base of “111 Project” for Biomechanics & Tissue Repair Engineering; Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China
| | - Muhammad Farrukh Nisar
- The Base of “111 Project” for Biomechanics & Tissue Repair Engineering; Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China
| | - Mao Lin
- Chongqing Traditional Chinese Medicine Hospital, Chongqing 400011, China
| | - Julia Li Zhong
- The Base of “111 Project” for Biomechanics & Tissue Repair Engineering; Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China
- Chongqing Traditional Chinese Medicine Hospital, Chongqing 400011, China
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4
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Ferreira PA. The coming-of-age of nucleocytoplasmic transport in motor neuron disease and neurodegeneration. Cell Mol Life Sci 2019; 76:2247-2273. [PMID: 30742233 PMCID: PMC6531325 DOI: 10.1007/s00018-019-03029-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 01/28/2019] [Indexed: 12/11/2022]
Abstract
The nuclear pore is the gatekeeper of nucleocytoplasmic transport and signaling through which a vast flux of information is continuously exchanged between the nuclear and cytoplasmic compartments to maintain cellular homeostasis. A unifying and organizing principle has recently emerged that cements the notion that several forms of amyotrophic lateral sclerosis (ALS), and growing number of other neurodegenerative diseases, co-opt the dysregulation of nucleocytoplasmic transport and that this impairment is a pathogenic driver of neurodegeneration. The understanding of shared pathomechanisms that underpin neurodegenerative diseases with impairments in nucleocytoplasmic transport and how these interface with current concepts of nucleocytoplasmic transport is bound to illuminate this fundamental biological process in a yet more physiological context. Here, I summarize unresolved questions and evidence and extend basic and critical concepts and challenges of nucleocytoplasmic transport and its role in the pathogenesis of neurodegenerative diseases, such as ALS. These principles will help to appreciate the roles of nucleocytoplasmic transport in the pathogenesis of ALS and other neurodegenerative diseases, and generate a framework for new ideas of the susceptibility of motoneurons, and possibly other neurons, to degeneration by dysregulation of nucleocytoplasmic transport.
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Affiliation(s)
- Paulo A Ferreira
- Duke University Medical Center, DUEC 3802, 2351 Erwin Road, Durham, NC, 27710, USA.
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5
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Enhanced diffusion by binding to the crosslinks of a polymer gel. Nat Commun 2018; 9:4348. [PMID: 30341303 PMCID: PMC6195553 DOI: 10.1038/s41467-018-06851-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 09/27/2018] [Indexed: 01/20/2023] Open
Abstract
Creating a selective gel that filters particles based on their interactions is a major goal of nanotechnology, with far-reaching implications from drug delivery to controlling assembly pathways. However, this is particularly difficult when the particles are larger than the gel's characteristic mesh size because such particles cannot passively pass through the gel. Thus, filtering requires the interacting particles to transiently reorganize the gel's internal structure. While significant advances, e.g., in DNA engineering, have enabled the design of nano-materials with programmable interactions, it is not clear what physical principles such a designer gel could exploit to achieve selective permeability. We present an equilibrium mechanism where crosslink binding dynamics are affected by interacting particles such that particle diffusion is enhanced. In addition to revealing specific design rules for manufacturing selective gels, our results have the potential to explain the origin of selective permeability in certain biological materials, including the nuclear pore complex.
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6
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Kumeta M, Konishi HA, Zhang W, Sakagami S, Yoshimura SH. Prolines in the α-helix confer the structural flexibility and functional integrity of importin-β. J Cell Sci 2018; 131:jcs.206326. [PMID: 29142102 DOI: 10.1242/jcs.206326] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 11/06/2017] [Indexed: 01/09/2023] Open
Abstract
The karyopherin family of nuclear transport receptors is composed of a long array of amphiphilic α-helices and undergoes flexible conformational changes to pass through the hydrophobic crowding barrier of the nuclear pore. Here, we focused on the characteristic enrichment of prolines in the middle of the outer α-helices of importin-β. When these prolines were substituted with alanine, nuclear transport activity was reduced drastically in vivo and in vitro, and caused a severe defect in mitotic progression. These mutations did not alter the overall folding of the helical repeat or affect its interaction with cargo or the regulatory factor Ran. However, in vitro and in silico analyses revealed that the mutant lost structural flexibility and could not undergo rapid conformational changes when transferring from a hydrophilic to hydrophobic environment or vice versa. These findings reveal the essential roles of prolines in ensuring the structural flexibility and functional integrity of karyopherins.
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Affiliation(s)
- Masahiro Kumeta
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Hide A Konishi
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Wanzhen Zhang
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Sayuri Sakagami
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Shige H Yoshimura
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
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7
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OKA M, YONEDA Y. Importin α: functions as a nuclear transport factor and beyond. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2018; 94:259-274. [PMID: 30078827 PMCID: PMC6117492 DOI: 10.2183/pjab.94.018] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Nucleocytoplasmic transport is an essential process in eukaryotes. The molecular mechanisms underlying nuclear transport that involve the nuclear transport receptor, small GTPase Ran, and the nuclear pore complex are highly conserved from yeast to humans. On the other hand, it has become clear that the nuclear transport system diverged during evolution to achieve various physiological functions in multicellular eukaryotes. In this review, we first summarize the molecular mechanisms of nuclear transport and how these were elucidated. Then, we focus on the diverse functions of importin α, which acts not merely an import factor but also as a multi-functional protein contributing to a variety of cellular functions in higher eukaryotes.
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Affiliation(s)
- Masahiro OKA
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
| | - Yoshihiro YONEDA
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
- Correspondence should be addressed: Y. Yoneda, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan (e-mail: )
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8
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Zhu R, Iwabuchi M, Ohsumi K. The WD40 Domain of HIRA Is Essential for RI-nucleosome Assembly in Xenopus Egg Extracts. Cell Struct Funct 2017; 42:37-48. [PMID: 28381790 DOI: 10.1247/csf.17001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Histone chaperones are a group of histone-binding proteins that facilitate the assembly of nucleosomes, the fundamental structural units of chromatin in eukaryotes. In nucleosome assembly, deposition of a histone H3-H4 tetramer onto DNA is the first and critical step, which is mediated by the histone chaperones HIRA and CAF-1. HIRA and CAF-1 are reportedly involved in DNA replication independent (RI) and replication coupled nucleosome assembly, respectively. However, the mechanisms by which they mediate histone deposition remain unclear. In this study, we focused on the mechanism by which HIRA induces RI-nucleosome assembly. We looked for HIRA domains that are required for nucleosome assembly and its localization to chromatin. We used cell-free extracts from Xenopus eggs that carry out RI-nucleosome assembly of plasmid DNA. We confirmed that HIRA formed stable complexes with Asf1, another histone H3-H4 chaperone, and the HIRA-Asf1 complex was solely responsible for RI-nucleosome assembly in egg extracts. We further demonstrated that the HIRA N-terminus containing the WD40 domain, which comprises seven WD40 repeats, and the B domain, to which Asf1 binds, were essential for RI-nucleosome assembly; the three WD40 repeats from the N-terminus were especially critical. Using egg extracts that reproduce nuclear formation accompanying the duplication of chromatin, we also demonstrated that the Hir domain was indispensable for the binding of HIRA to chromatin. Thus, the WD40 and B domains are the core elements for inducing RI-nucleosome assembly. Hir domain regulates the binding to chromatin. Based on these findings, similarities and differences between HIRA and CAF-1 are discussed.
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Affiliation(s)
- Ruibin Zhu
- Group of Developmental Cell Biology, Graduate School of Science, Nagoya University
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9
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Port SA, Monecke T, Dickmanns A, Spillner C, Hofele R, Urlaub H, Ficner R, Kehlenbach RH. Structural and Functional Characterization of CRM1-Nup214 Interactions Reveals Multiple FG-Binding Sites Involved in Nuclear Export. Cell Rep 2015; 13:690-702. [PMID: 26489467 DOI: 10.1016/j.celrep.2015.09.042] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 08/11/2015] [Accepted: 09/14/2015] [Indexed: 12/11/2022] Open
Abstract
CRM1 is the major nuclear export receptor. During translocation through the nuclear pore, transport complexes transiently interact with phenylalanine-glycine (FG) repeats of multiple nucleoporins. On the cytoplasmic side of the nuclear pore, CRM1 tightly interacts with the nucleoporin Nup214. Here, we present the crystal structure of a 117-amino-acid FG-repeat-containing fragment of Nup214, in complex with CRM1, Snurportin 1, and RanGTP at 2.85 Å resolution. The structure reveals eight binding sites for Nup214 FG motifs on CRM1, with intervening stretches that are loosely attached to the transport receptor. Nup214 binds to N- and C-terminal regions of CRM1, thereby clamping CRM1 in a closed conformation and stabilizing the export complex. The role of conserved hydrophobic pockets for the recognition of FG motifs was analyzed in biochemical and cell-based assays. Comparative studies with RanBP3 and Nup62 shed light on specificities of CRM1-nucleoporin binding, which serves as a paradigm for transport receptor-nucleoporin interactions.
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Affiliation(s)
- Sarah A Port
- Department of Molecular Biology, Faculty of Medicine, GZMB, Georg-August-University Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Thomas Monecke
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Achim Dickmanns
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Christiane Spillner
- Department of Molecular Biology, Faculty of Medicine, GZMB, Georg-August-University Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Romina Hofele
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Bioanalytics, Institute for Clinical Chemistry, University Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Bioanalytics, Institute for Clinical Chemistry, University Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
| | - Ralph H Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, GZMB, Georg-August-University Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
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10
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Tsujii A, Miyamoto Y, Moriyama T, Tsuchiya Y, Obuse C, Mizuguchi K, Oka M, Yoneda Y. Retinoblastoma-binding Protein 4-regulated Classical Nuclear Transport Is Involved in Cellular Senescence. J Biol Chem 2015; 290:29375-88. [PMID: 26491019 DOI: 10.1074/jbc.m115.681908] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Indexed: 12/19/2022] Open
Abstract
Nucleocytoplasmic trafficking is a fundamental cellular process in eukaryotic cells. Here, we demonstrated that retinoblastoma-binding protein 4 (RBBP4) functions as a novel regulatory factor to increase the efficiency of importin α/β-mediated nuclear import. RBBP4 accelerates the release of importin β1 from importin α via competitive binding to the importin β-binding domain of importin α in the presence of RanGTP. Therefore, it facilitates importin α/β-mediated nuclear import. We showed that the importin α/β pathway is down-regulated in replicative senescent cells, concomitant with a decrease in RBBP4 level. Knockdown of RBBP4 caused both suppression of nuclear transport and induction of cellular senescence. This is the first report to identify a factor that competes with importin β1 to bind to importin α, and it demonstrates that the loss of this factor can trigger cellular senescence.
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Affiliation(s)
- Akira Tsujii
- From the Graduate School of Medicine and the Laboratories of Nuclear Transport Dynamics and
| | | | | | | | - Chikashi Obuse
- the Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan
| | | | - Masahiro Oka
- the Laboratories of Nuclear Transport Dynamics and Laboratory of Biomedical Innovation, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871,
| | - Yoshihiro Yoneda
- Laboratory of Biomedical Innovation, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871, National Institutes of Biomedical Innovation, Health and Nutrition, Ibaraki, Osaka 567-0085, and
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11
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Song J, Kose S, Watanabe A, Son SY, Choi S, Hong H, Yamashita E, Park IY, Imamoto N, Lee SJ. Structural and functional analysis of Hikeshi, a new nuclear transport receptor of Hsp70s. ACTA ACUST UNITED AC 2015; 71:473-83. [PMID: 25760597 DOI: 10.1107/s1399004714026881] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 12/08/2014] [Indexed: 11/10/2022]
Abstract
Hikeshi is a nuclear transport receptor required for cell survival after stress. It mediates heat-shock-induced nuclear import of 70 kDa heat-shock proteins (Hsp70s) through interactions with FG-nucleoporins (FG-Nups), which are proteins in nuclear pore complexes (NPCs). Here, the crystal structure of human Hikeshi is presented at 1.8 Å resolution. Hikeshi forms an asymmetric homodimer that is responsible for the interaction with Hsp70s. The asymmetry of Hikeshi arises from the distinct conformation of the C-terminal domain (CTD) and the flexibility of the linker regions of each monomer. Structure-guided mutational analyses showed that both the flexible linker region and the CTD are important for nuclear import of Hsp70. Pull-down assays revealed that only full-length Hsp70s can interact with Hikeshi. The N-terminal domain (NTD) consists of a jelly-roll/β-sandwich fold structure which contains hydrophobic pockets involved in FG-Nup recognition. A unique extended loop (E-loop) in the NTD is likely to regulate the interactions of Hikeshi with FG-Nups. The crystal structure of Hikeshi explains how Hikeshi participates in the regulation of nuclear import through the recognition of FG-Nups and which part of Hikeshi affects its binding to Hsp70. This study is the first to yield structural insight into this highly unique import receptor.
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Affiliation(s)
- Jinsue Song
- College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Shingo Kose
- Cellular Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Ai Watanabe
- Cellular Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Se Young Son
- College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Saehae Choi
- College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Hyerim Hong
- College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Eiki Yamashita
- Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Il Yeong Park
- College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Naoko Imamoto
- Cellular Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Soo Jae Lee
- College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea
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12
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Nucleocytoplasmic transport under stress conditions and its role in HSP70 chaperone systems. Biochim Biophys Acta Gen Subj 2014; 1840:2953-60. [DOI: 10.1016/j.bbagen.2014.04.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 04/11/2014] [Accepted: 04/28/2014] [Indexed: 11/20/2022]
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13
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Wang L, Liu X, Gusev E, Wang C, Fagotto F. Regulation of the phosphorylation and nuclear import and export of β-catenin by APC and its cancer-related truncated form. J Cell Sci 2014; 127:1647-59. [PMID: 24496450 DOI: 10.1242/jcs.131045] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We report the first direct analysis of the endogenous β-catenin phosphorylation activity in colon cancer SW480 cells. By comparing parental SW480 cells that harbor a typical truncated adenomatous polyposis coli (APC) form, cells expressing full-length APC and APC-depleted cells, we provide the formal demonstration that APC is necessary for β-catenin phosphorylation, both for priming of the protein at residue serine 45 and for the subsequent phosphorylation of residues 33, 37 and 41. Truncated APC still sustains a surprisingly high phosphorylation activity, which requires the protein to bind to β-catenin through the APC 20-amino-acid (20AA) repeats, thus providing a biochemical explanation for the precise truncations found in cancer cells. We also show that most of the β-catenin phosphorylation activity is associated with a dense insoluble fraction. We finally examine the impact of full-length and truncated APC on β-catenin nuclear transport. We observe that β-catenin is transported much faster than previously thought. Although this fast translocation is largely insensitive to the presence of wild-type or truncated APC, the two forms appear to limit the pool of β-catenin that is available for transport, which could have an impact on β-catenin nuclear activities in normal and cancer cells.
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Affiliation(s)
- Lili Wang
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China
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14
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Furuta M, Kose S, Kehlenbach RH, Imamoto N. Analysis of Nucleocytoplasmic Transport in Digitonin-Permeabilized Cells Under Different Cellular Conditions. Methods Cell Biol 2014; 122:331-52. [DOI: 10.1016/b978-0-12-417160-2.00015-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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15
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Kim J, Izadyar A, Nioradze N, Amemiya S. Nanoscale mechanism of molecular transport through the nuclear pore complex as studied by scanning electrochemical microscopy. J Am Chem Soc 2013; 135:2321-9. [PMID: 23320434 PMCID: PMC3572272 DOI: 10.1021/ja311080j] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The nuclear pore complex (NPC) is the proteinaceous nanopore that solely mediates molecular transport across the nuclear envelope between the nucleus and cytoplasm of a eukaryotic cell. Small molecules (<40 kDa) diffuse through the large pore of this multiprotein complex. A passively impermeable macromolecule tagged with a signal peptide is chaperoned through the nanopore by nuclear transport receptors (e.g., importins) owing to their interactions with barrier-forming proteins. Presently, this bimodal transport mechanism is not well understood and is described by controversial models. Herein, we report on a dynamic and spatially resolved mechanism for NPC-mediated molecular transport through nanoscale central and peripheral routes with distinct permeabilities. Specifically, we develop a nanogap-based approach of scanning electrochemical microscopy to precisely measure the extremely high permeability of the nuclear envelope to a small probe molecule, (ferrocenylmethyl)trimethylammonium. Effective medium theories indicate that the passive permeability of 5.9 × 10(-2) cm/s corresponds to the free diffusion of the probe molecule through ~22 nanopores with a radius of 24 nm and a length of 35 nm. Peripheral routes are blocked by wheat germ agglutinin to yield 2-fold lower permeability for 17 nm-radius central routes. This lectin is also used in fluorescence assays to find that importins facilitate the transport of signal-tagged albumin mainly through the 7 nm-thick peripheral route rather than through the sufficiently large central route. We propose that this spatial selectivity is regulated by the conformational changes in barrier-forming proteins that transiently and locally expand the impermeably thin peripheral route while blocking the central route.
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Affiliation(s)
- Jiyeon Kim
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260
| | | | - Nikoloz Nioradze
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260
| | - Shigeru Amemiya
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania, 15260
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16
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Kawazu T, Kanzaki H, Uno A, Azuma H, Nagasaki T. HVJ-E/importin-β hybrid vector for overcoming cytoplasmic and nuclear membranes as double barrier for non-viral gene delivery. Biomed Pharmacother 2012; 66:519-24. [DOI: 10.1016/j.biopha.2012.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 02/29/2012] [Indexed: 10/28/2022] Open
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17
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Imamoto N, Kose S. Heat-shock stress activates a novel nuclear import pathway mediated by Hikeshi. Nucleus 2012; 3:422-8. [PMID: 22895094 PMCID: PMC3474662 DOI: 10.4161/nucl.21713] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Cellular stresses significantly affect nuclear transport systems. Nuclear transport pathways mediated by importin β-family members, which are active under normal conditions, are downregulated. During thermal stress, a nuclear import pathway mediated by a novel carrier, which we named Hikeshi, becomes active. Hikeshi is not a member of the importin β family and mediates the nuclear import of Hsp70s. Unlike importin β family-mediated nuclear transport, the Hikeshi-mediated nuclear import of Hsp70s is not coupled to the GTPase cycle of the small GTPase Ran but rather is coupled with the ATPase cycle of Hsp70s. Hikeshi-mediated nuclear import is essential for the attenuation and reversal of the thermal stress response in human cells. The mechanism and functions of this newly identified nuclear import pathway will be discussed.
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Affiliation(s)
- Naoko Imamoto
- Cellular Dynamics Laboratory; RIKEN Advanced Science Institute; Wako, Saitama, Japan.
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18
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Kose S, Furuta M, Imamoto N. Hikeshi, a Nuclear Import Carrier for Hsp70s, Protects Cells from Heat Shock-Induced Nuclear Damage. Cell 2012; 149:578-89. [DOI: 10.1016/j.cell.2012.02.058] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 11/21/2011] [Accepted: 02/24/2012] [Indexed: 12/15/2022]
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19
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Tetenbaum-Novatt J, Hough LE, Mironska R, McKenney AS, Rout MP. Nucleocytoplasmic transport: a role for nonspecific competition in karyopherin-nucleoporin interactions. Mol Cell Proteomics 2012; 11:31-46. [PMID: 22357553 DOI: 10.1074/mcp.m111.013656] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleocytoplasmic transport occurs through the nuclear pore complex (NPC), which in yeast is a ~50 MDa complex consisting of ~30 different proteins. Small molecules can freely exchange through the NPC, but macromolecules larger than ~40 kDa must be aided across by transport factors, most of which belong to a related family of proteins termed karyopherins (Kaps). These transport factors bind to the disordered phenylalanine-glycine (FG) repeat domains in a family of NPC proteins termed FG nups, and this specific binding allows the transport factors to cross the NPC. However, we still know little in terms of the molecular and kinetic details regarding how this binding translates to selective passage of transport factors across the NPC. Here we show that the specific interactions between Kaps and FG nups are strongly modulated by the presence of a cellular milieu whose proteins appear to act as very weak competitors that nevertheless collectively can reduce Kap/FG nup affinities by several orders of magnitude. Without such modulation, the avidities between Kaps and FG nups measured in vitro are too tight to be compatible with the rapid transport kinetics observed in vivo. We modeled the multivalent interactions between the disordered repeat binding sites in the FG nups and multiple cognate binding sites on Kap, showing that they should indeed be sensitive to even weakly binding competitors; the introduction of such competition reduces the availability of these binding sites, dramatically lowering the avidity of their specific interactions and allowing rapid nuclear transport.
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Affiliation(s)
- Jaclyn Tetenbaum-Novatt
- The Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, New York 10065, USA
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20
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Fluorescence correlation spectroscopy of intact nuclear pore complexes. Biophys J 2011; 101:L27-9. [PMID: 21843462 DOI: 10.1016/j.bpj.2011.04.057] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 04/02/2011] [Accepted: 04/11/2011] [Indexed: 01/06/2023] Open
Abstract
No methods proposed thus far have the sensitivity to measure the transport of single molecules through single nuclear pore complexes (NPCs) in intact cells. Here we demonstrate that fluorescence correlation spectroscopy (FCS) combined with real-time tracking of the center of mass of single NPCs in live, unperturbed cells allows us to detect the transport of single molecules in a reference system of a pore with high temporal (millisecond) and spatial (limited by diffraction) resolution. We find that the transport of the classical receptor karyopherin-β1 (Kapβ1) is regulated so as to produce a peculiar distribution of characteristic times at the NPC. This regulation, which is spatially restricted to the pore, depends on the properties and metabolic energy of Kapβ1. As such, this method provides a powerful tool for studying nucleocytoplasmic shuttling at the nanometer scale under physiological conditions.
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21
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Wang X, Xu X, Zhu S, Xiao Z, Ma Z, Li Y, Wang Y. Molecular dynamics simulation of conformational heterogeneity in transportin 1. Proteins 2011; 80:382-97. [PMID: 22105828 DOI: 10.1002/prot.23193] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 08/23/2011] [Accepted: 09/04/2011] [Indexed: 11/10/2022]
Abstract
Transportin 1 (Trn1), as a typical transport receptor of the karyopherin-β family, mediates numerous RNA binding proteins into the nucleus by recognizing proline-tyrosine nuclear localization signals (PY-NLSs). Such process is regulated by RanGTP through its nucleotide cycle, which is associated with ligand dissociation. Yet a proper description including dynamic properties of Trn1 and its response on ligand/Ran binding has not been accessible so far. Here, we use molecular dynamics simulations to probe the conformational dynamics of the apo-Trn1 and Trn1 in complex with ligand and Ran. The results reveal a strikingly intrinsic flexibility and conformational heterogeneity of Trn1, identified as generally segmental architecture. The segments rotate relative to each other about a flexible hinge and thereby force Trn1 to adopt a conformation compatible with the binding of Ran or substrates. Such binding significantly suppresses the flexibility and conformational heterogeneity of Trn1 and results in a disorder-to-order transition of HR8 loop, which facilitates this loop to allosterically communicate with the C-terminal arch of Trn1. These results give insights into the disassembly and recycling of the Trn1, which has important implications for the regulation of the nuclear transport cycle and for the ligand selectivity.
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Affiliation(s)
- Xia Wang
- Center of Bioinformatics, Northwest A&F University, Yangling, Shaanxi 712100, People's Republic of China; College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, People's Republic of China
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22
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Chen J, Liu MY, Parish CR, Chong BH, Khachigian L. Nuclear import of early growth response-1 involves importin-7 and the novel nuclear localization signal serine-proline-serine. Int J Biochem Cell Biol 2011; 43:905-12. [DOI: 10.1016/j.biocel.2011.03.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 03/04/2011] [Accepted: 03/09/2011] [Indexed: 01/12/2023]
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23
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Yang FM, Lin YC, Hu MC. Identification of two functional nuclear localization signals mediating nuclear import of liver receptor homologue-1. Cell Mol Life Sci 2011; 68:1241-53. [PMID: 20853131 PMCID: PMC11114538 DOI: 10.1007/s00018-010-0521-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 08/03/2010] [Accepted: 08/27/2010] [Indexed: 10/19/2022]
Abstract
Liver receptor homologue-1 (LRH-1) is a member of the nuclear receptor superfamily. We characterized two functional nuclear localization signals (NLSs) in LRH-1. NLS1 (residues 117-168) overlaps the second zinc finger in the DNA binding domain. Mutagenesis showed that the zinc finger structure and two basic clusters on either side of the zinc finger loop are critical for nuclear import of NLS1. NLS2 (residues 169-204) is located in the Ftz-F1 box that contains a bipartite signal. In full-length LRH-1, mutation of either NLS1 or NLS2 had no effect on nuclear localization, but disruption of both NLS1 and NLS2 resulted in the cytoplasmic accumulation of LRH-1. Either NLS1 or NLS2 alone was sufficient to target LRH-1 to the nucleus. Both NLS1 and NLS2 mediate nuclear transport by a mechanism involving importin α/β. Finally, we showed that three crucial basic clusters in the NLSs are involved in the DNA binding and transcriptional activities of LRH-1.
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Affiliation(s)
- Feng-Ming Yang
- Graduate Institute of Physiology, National Taiwan University College of Medicine, No. 1, Jen-Ai Road, 1st Section, Taipei, 100 Taiwan
| | - Yu-Chi Lin
- Graduate Institute of Physiology, National Taiwan University College of Medicine, No. 1, Jen-Ai Road, 1st Section, Taipei, 100 Taiwan
| | - Meng-Chun Hu
- Graduate Institute of Physiology, National Taiwan University College of Medicine, No. 1, Jen-Ai Road, 1st Section, Taipei, 100 Taiwan
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24
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Colwell LJ, Brenner MP, Ribbeck K. Charge as a selection criterion for translocation through the nuclear pore complex. PLoS Comput Biol 2010; 6:e1000747. [PMID: 20421988 PMCID: PMC2858669 DOI: 10.1371/journal.pcbi.1000747] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 03/18/2010] [Indexed: 01/17/2023] Open
Abstract
Nuclear pore complexes (NPCs) are highly selective filters that control the exchange of material between nucleus and cytoplasm. The principles that govern selective filtering by NPCs are not fully understood. Previous studies find that cellular proteins capable of fast translocation through NPCs (transport receptors) are characterized by a high proportion of hydrophobic surface regions. Our analysis finds that transport receptors and their complexes are also highly negatively charged. Moreover, NPC components that constitute the permeability barrier are positively charged. We estimate that electrostatic interactions between a transport receptor and the NPC result in an energy gain of several kBT, which would enable significantly increased translocation rates of transport receptors relative to other cellular proteins. We suggest that negative charge is an essential criterion for selective passage through the NPC. All proteins that move between the cytoplasm and the nucleus must pass through nuclear pore complexes, large aqueous channels around 40nm in diameter. In some cases the nuclear envelope is perforated with several thousand nuclear pore complexes, while in other cases they are few and far between. Macromolecular transport through nuclear pores is highly regulated; an elaborate system, involving the binding and unbinding of accessory proteins (transport receptors), allows regulation of which proteins can pass through the pores. The basic principles that govern this selective filtering are not fully understood. Some proteins pass through the pore without binding to transport receptors, while others require the binding of multiple transport receptors for efficient translocation. How does the pore select which proteins can pass through, and which cannot? This paper carries out a biophysical analysis of the properties of proteins that can translocate through the nuclear pore. We find that proteins capable of fast translocation are highly negatively charged, whereas proteins that cannot pass through the pore are positively charged. Moreover, proteins that constitute the interior of the pore channel itself are net positively charged. This suggests that electrostatic interactions between translocating proteins and the pore are an essential part of the selective filtering mechanism.
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Affiliation(s)
- Lucy J. Colwell
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America
| | - Michael P. Brenner
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (MPB); (KR)
| | - Katharina Ribbeck
- FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (MPB); (KR)
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25
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Kosako H, Imamoto N. Phosphorylation of nucleoporins: signal transduction-mediated regulation of their interaction with nuclear transport receptors. Nucleus 2010; 1:309-13. [PMID: 21327077 DOI: 10.4161/nucl.1.4.11744] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/01/2010] [Accepted: 01/26/2010] [Indexed: 11/19/2022] Open
Abstract
The nuclear pore complex (NPC) is composed of ∼30 unique proteins, collectively referred to as nucleoporins or Nups. While metazoan Nups are known to be phosphorylated during mitosis to cause disassembly of the NPC, what is less clear is whether Nups are phosphorylated and regulated by extracellular stimuli in interphase cells. Our multi-step phosphoproteomic approach revealed a number of physiologically relevant extracellular signal-regulated kinase (ERK) targets, including Nups containing FG repeats (FG Nups) that provide binding sites for nuclear transport receptors (NTRs) during the NPC passage. The phosphorylation of FG Nups by ERK does not affect the overall architecture of the NPC but directly inhibits their interactions with NTRs and regulates the permeability barrier properties of the NPC. Such regulation at the levels of transport machinery is expected to have a broad impact on cellular physiology through the spatiotemporal control of signaling events. Until recently, many studies have focused on cellular signaling-mediated phosphorylation of individual cargo proteins, such as transcription factors. An understanding of the effects of signaling pathways on nucleocytoplasmic transport machinery is only beginning to emerge.
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Affiliation(s)
- Hidetaka Kosako
- Division of Disease Proteomics; Institute for Enzyme Research; The University of Tokushima; Tokushima, Japan.
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26
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Peters R. Functionalization of a nanopore: the nuclear pore complex paradigm. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1793:1533-9. [PMID: 19596381 PMCID: PMC2756448 DOI: 10.1016/j.bbamcr.2009.06.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 06/26/2009] [Accepted: 06/30/2009] [Indexed: 10/20/2022]
Abstract
Biological cells maintain a myriad of nanopores which, although relying on the same basic small-hole principle, serve a large variety of functions. Here we consider how the nuclear pore complex (NPC), a large nanopore mediating the traffic between genetic material and protein synthesizing apparatus, is functionalized to carry out a set of transport functions. A major parameter of NPC functionalization is a lining of it external and internal surfaces with so-called phenylalanine glycine (FG) proteins. FG proteins integrate a multitude of transport factor binding sites into intrinsically disordered domains. This surprising finding has given rise to a number of transport models assigning direct gating functions to FG proteins. However, recent data suggest that the properties of FG proteins cannot be properly assessed by considering only the purified, transport-factor-stripped NPC. At physiological conditions transport factors may shape FG proteins in a way allotting an essential role to surface diffusion, reconciling tight binding with efficient transport. Thus, NPC studies are revealing both general traits and novel aspects of nanopore functionalization. In addition, they inspire artificial molecule sorters for proteomic and pharmaceutical applications.
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Affiliation(s)
- Reiner Peters
- The Rockefeller University, Laboratory for mass spectrometry and gaseous ion chemistry, 1230 York Avenue, New York, NY 10065, USA.
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27
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Vázquez-Iglesias L, Lostalé-Seijo I, Martínez-Costas J, Benavente J. Avian reovirus sigmaA localizes to the nucleolus and enters the nucleus by a nonclassical energy- and carrier-independent pathway. J Virol 2009; 83:10163-75. [PMID: 19640987 PMCID: PMC2747991 DOI: 10.1128/jvi.01080-09] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 07/16/2009] [Indexed: 12/24/2022] Open
Abstract
Avian reovirus sigmaA is a double-stranded RNA (dsRNA)-binding protein that has been shown to stabilize viral core particles and to protect the virus against the antiviral action of interferon. To continue with the characterization of this viral protein, we have investigated its intracellular distribution in avian cells. Most sigmaA accumulates into cytoplasmic viral factories of infected cells, and yet a significant fraction was detected in the nucleolus. The protein also localizes in the nucleolus of transfected cells, suggesting that nucleolar targeting is not facilitated by the viral infection or by viral factors. Assays performed in both intact cells and digitonin-permeabilized cells demonstrate that sigmaA is able to enter the nucleus via a nucleoporin-dependent nondiffusional mechanism that does not require added cytosolic factors or energy input. These results indicate that sigmaA by itself is able to penetrate into the nucleus using a process that is mechanistically different from the classical nuclear localization signal/importin pathway. On the other hand, two sigmaA arginines that are necessary for dsRNA binding are also required for nucleolar localization, suggesting that dsRNA-binding and nucleolar targeting are intimately linked properties of the viral protein.
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Affiliation(s)
- Lorena Vázquez-Iglesias
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Santiago de Compostela, Santiago de Compostela, Spain
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28
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Phosphoproteomics reveals new ERK MAP kinase targets and links ERK to nucleoporin-mediated nuclear transport. Nat Struct Mol Biol 2009; 16:1026-35. [DOI: 10.1038/nsmb.1656] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Accepted: 07/14/2009] [Indexed: 11/09/2022]
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29
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30
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Naim B, Zbaida D, Dagan S, Kapon R, Reich Z. Cargo surface hydrophobicity is sufficient to overcome the nuclear pore complex selectivity barrier. EMBO J 2009; 28:2697-705. [PMID: 19680225 DOI: 10.1038/emboj.2009.225] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2009] [Accepted: 06/18/2009] [Indexed: 11/09/2022] Open
Abstract
To fulfil their function, nuclear pore complexes (NPCs) must discriminate between inert proteins and nuclear transport receptors (NTRs), admitting only the latter. This specific permeation is thought to depend on interactions between hydrophobic patches on NTRs and phenylalanine-glycine (FG) or related repeats that line the NPC. Here, we tested this premise directly by conjugating different hydrophobic amino-acid analogues to the surface of an inert protein and examining its ability to cross NPCs unassisted by NTRs. Conjugation of as few as four hydrophobic moieties was sufficient to enable passage of the protein through NPCs. Transport of the modified protein proceeded with rates comparable to those measured for the innate protein when bound to an NTR and was relatively insensitive both to the nature and density of the amino acids used to confer hydrophobicity. The latter observation suggests a non-specific, small, and plant interaction network between cargo and FG repeats.
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Affiliation(s)
- Bracha Naim
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
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31
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Wu J, Corbett AH, Berland KM. The intracellular mobility of nuclear import receptors and NLS cargoes. Biophys J 2009; 96:3840-9. [PMID: 19413990 DOI: 10.1016/j.bpj.2009.01.050] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 01/15/2009] [Accepted: 01/28/2009] [Indexed: 12/27/2022] Open
Abstract
We have investigated classical nuclear localization sequence (NLS) mediated protein trafficking by measuring biomolecular dynamics within living cells using two-photon fluorescence correlation spectroscopy. By directly observing the behavior of specific molecules in their native cellular environment, it is possible to uncover functional details that are not apparent from traditional biochemical investigations or functional assays. We show that the intracellular mobility of NLS cargoes and their import receptor proteins, karyopherin-alpha and karyopherin-beta, can be robustly measured and that quantitative comparison of intracellular diffusion coefficients provides new insights into nuclear transport mechanisms. Import cargo complexes are assembled throughout the cytoplasm, and their diffusion is slower than predicted by molecular weight due to specific interactions. Analysis of NLS cargo diffusion in the cytoplasm indicates that these interactions are likely disrupted by NLS cargo binding. Our results suggest that delivery of import receptors and NLS cargoes to nuclear pores may complement selective translocation through the pores as a functional mechanism for regulating transport of proteins into the nucleus.
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Affiliation(s)
- Jianrong Wu
- Department of Physics, Emory University, Atlanta, GA 30322, USA
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32
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Abstract
Transport through the nuclear pore complex (NPC), a keystone of the eukaryotic building plan, is known to involve a large channel and an abundance of phenylalanine-glycine (FG) protein domains serving as binding sites for soluble nuclear transport receptors and their cargo complexes. However, the conformation of the FG domains in vivo, their arrangement in relation to the transport channel and their function(s) in transport are still vividly debated. Here, we revisit a number of representative transport models-specifically Brownian affinity gating, selective phase gating, reversible FG domain collapse, and reduction of dimensionality (ROD)-in the light of new data obtained by optical single transporter recording, optical superresolution microscopy, artificial nanopores, and many other techniques. The analysis suggests that a properly adapted, simplified version of the ROD model accounts well for the available data. This has implications for nucleocytoplasmic transport in general.
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Affiliation(s)
- Reiner Peters
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY 10065 , USA.
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33
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Kabuta T, Take K, Kabuta C, Hakuno F, Takahashi SI. Differential subcellular localization of insulin receptor substrates depends on C-terminal regions and importin beta. Biochem Biophys Res Commun 2008; 377:741-6. [PMID: 18835249 DOI: 10.1016/j.bbrc.2008.09.106] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 09/25/2008] [Indexed: 10/21/2022]
Abstract
Insulin receptor substrates (IRSs) play essential roles in signal transduction of insulin and insulin-like growth factors. Previously, we showed that IRS-3 is localized to the nucleus as well as the cytosol, while IRS-1 and 2 are mainly localized to the cytoplasm. In the present study, we found that importin beta directly interacts with IRS-3 and is able to mediate nuclear transport of IRS-3. Importin beta interacted with the pleckstrin homology domain, the phosphotyrosine binding domain and the C-terminal region of IRS-3; indeed all of these fragments exhibited predominant nuclear localization. By contrast, almost no interaction of importin beta with IRS-1 and -2 was observed, and their C-terminal regions displayed discrete spotty images in the cytosol. In addition, using chimeric proteins between IRS-1 and IRS-3, we revealed that the C-terminal regions are the main determinants of the differing subcellular localizations of IRS-1 and IRS-3.
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Affiliation(s)
- Tomohiro Kabuta
- Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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34
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Sorokin AV, Kim ER, Ovchinnikov LP. Nucleocytoplasmic transport of proteins. BIOCHEMISTRY (MOSCOW) 2008; 72:1439-57. [PMID: 18282135 DOI: 10.1134/s0006297907130032] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In eukaryotic cells, the movement of macromolecules between the nucleus and cytoplasm occurs through the nuclear pore complex (NPC)--a large protein complex spanning the nuclear envelope. The nuclear transport of proteins is usually mediated by a family of transport receptors known as karyopherins. Karyopherins bind to their cargoes via recognition of nuclear localization signal (NLS) for nuclear import or nuclear export signal (NES) for export to form a transport complex. Its transport through NPC is facilitated by transient interactions between the karyopherins and NPC components. The interactions of karyopherins with their cargoes are regulated by GTPase Ran. In the current review, we describe the NPC structure, NLS, and NES, as well as the model of classic Ran-dependent transport, with special emphasis on existing alternative mechanisms; we also propose a classification of the basic mechanisms of protein transport regulation.
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Affiliation(s)
- A V Sorokin
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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35
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Tahara K, Takagi M, Ohsugi M, Sone T, Nishiumi F, Maeshima K, Horiuchi Y, Tokai-Nishizumi N, Imamoto F, Yamamoto T, Kose S, Imamoto N. Importin-beta and the small guanosine triphosphatase Ran mediate chromosome loading of the human chromokinesin Kid. ACTA ACUST UNITED AC 2008; 180:493-506. [PMID: 18268099 PMCID: PMC2234231 DOI: 10.1083/jcb.200708003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nucleocytoplasmic transport factors mediate various cellular processes, including nuclear transport, spindle assembly, and nuclear envelope/pore formation. In this paper, we identify the chromokinesin human kinesin-like DNA binding protein (hKid) as an import cargo of the importin-alpha/beta transport pathway and determine its nuclear localization signals (NLSs). Upon the loss of its functional NLSs, hKid exhibited reduced interactions with the mitotic chromosomes of living cells. In digitonin-permeabilized mitotic cells, hKid was bound only to the spindle and not to the chromosomes themselves. Surprisingly, hKid bound to importin-alpha/beta was efficiently targeted to mitotic chromosomes. The addition of Ran-guanosine diphosphate and an energy source, which generates Ran-guanosine triphosphate (GTP) locally at mitotic chromosomes, enhanced the importin-beta-mediated chromosome loading of hKid. Our results indicate that the association of importin-beta and -alpha with hKid triggers the initial targeting of hKid to mitotic chromosomes and that local Ran-GTP-mediated cargo release promotes the accumulation of hKid on chromosomes. Thus, this study demonstrates a novel nucleocytoplasmic transport factor-mediated mechanism for targeting proteins to mitotic chromosomes.
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Affiliation(s)
- Kiyoshi Tahara
- Cellular Dynamics Laboratory, Discovery Research Institute, Institute of Physical and Chemical Research, Wako, Saitama, 351-0198, Japan
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36
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Nakahara S, Raz A. Regulation of cancer-related gene expression by galectin-3 and the molecular mechanism of its nuclear import pathway. Cancer Metastasis Rev 2008; 26:605-10. [PMID: 17726578 PMCID: PMC3613988 DOI: 10.1007/s10555-007-9095-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Galectin-3 (Gal-3), a member of the beta-galactoside-binding gene family, distributes inside and outside the cell and has pleiotropic biological functions such as cell growth, cell adhesion, cell-cell interaction, and mRNA processing in a specific situation. In particular, Gal-3 in the nucleus plays a pivotal role in the regulation of cancer-related gene expression, including cyclin D1, TTF-1 and MUC2, presumably associated with tumor progression. Therefore, to understand the mechanism of nuclear import of Gal-3 is very significant and might be developed to the new approach for the cancer treatment. In this review, we focus on the role of Gal-3 in the nucleus and the molecular mechanism of nuclear import pathways of Gal-3, providing the hints for the inhibition of Gal-3 function.
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Affiliation(s)
- Susumu Nakahara
- Tumor Progression and Metastasis Program, Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA. Suita Municipal Hospital, Suita, Osaka, Japan
| | - Avraham Raz
- Tumor Progression and Metastasis Program, Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA
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37
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Meyer T, Vinkemeier U. STAT nuclear translocation: potential for pharmacological intervention. Expert Opin Ther Targets 2007; 11:1355-65. [PMID: 17907964 DOI: 10.1517/14728222.11.10.1355] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The signal transducer and activator of transcription (STAT) proteins are extracellular ligand-responsive transcription factors that mediate broadly diverse biological processes, including cell proliferation, transformation, apoptosis, differentiation, fetal development, inflammation and immune response. Stimulation with multiple cytokines or growth factors all result in the tyrosine phosphorylation of STAT proteins and the subsequent gene regulation via their direct binding to the promoters of responsive genes. Cytokine-regulated gene activation is dependent on the continuous nucleocytoplasmic cycling of STAT signal transducers. The STATs use intricately intertwined karyopherin-dependent and -independent translocation mechanisms to coordinate the activation step at the cell membrane and gene expression in the nucleus. In addition, STATs appear to have cytokine-independent gene regulatory functions that may also depend on their regulated nucleocytoplasmic transfer. Numerous studies have implicated aberrant STAT signalling in cancer, immune defects and inflammatory diseases. Given the central role of intracellular trafficking for the proper signal processing by STAT proteins, pharmacological targeting of STAT nucleocytoplasmic translocation appears to be an attractive strategy to interfere with dysregulated cytokine signalling. This review will discuss possible scenarios that would result from the use of novel modulators of STAT shuttling, which may both increase or decrease STAT activation and, hence, transcriptional activity.
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Affiliation(s)
- Thomas Meyer
- Philipps-Universität Marburg, Klinik für Kardiologie und Klinik für Psychosomatische Medizin und Psychotherapie, Baldingerstrasse 1, 35033 Marburg, Germany.
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Wiegert JS, Bengtson CP, Bading H. Diffusion and not active transport underlies and limits ERK1/2 synapse-to-nucleus signaling in hippocampal neurons. J Biol Chem 2007; 282:29621-33. [PMID: 17675293 DOI: 10.1074/jbc.m701448200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The propagation of signals from synapses and dendrites to the nucleus is crucial for long lasting adaptive changes in the nervous system. The ERK-MAPK pathway can link neuronal activity and cell surface receptor activation to the regulation of gene transcription, and it is often considered the principal mediator of synapse-to-nucleus communication in late-phase plasticity and learning. However, the mechanisms underlying ERK1/2 trafficking in dendrites and nuclear translocation in neurons remain to be determined leaving it unclear whether ERK1/2 activated at the synapse can contribute to nuclear signaling and transcriptional regulation. Using the photobleachable and photoactivable fluorescent tag Dronpa on ERK1 and ERK2, we show here that ERK1/2 translocation to the nucleus of hippocampal neurons is induced by the stimulation of N-methyl-D-aspartate receptors or TrkB stimulation and is apparently mediated by facilitated diffusion. In contrast, ERK1/2 trafficking within dendrites is not signal-regulated and is mediated by passive diffusion. Within dendrites, the reach of a locally activated pool of ERK1/2 is very limited and follows an exponential decay with distance. These results indicate that successful signal propagation to the nucleus by the ERK-MAPK pathway depends on the distance of the nucleus from the site of ERK1/2 activation. ERK1/2 activated within or near the soma may rapidly reach the nucleus to induce gene expression, whereas ERK1/2 activated at distal synapses may only contribute to local signaling.
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Affiliation(s)
- J Simon Wiegert
- Department of Neurobiology, Interdisciplinary Center for Neurosciences, University of Heidelberg, 69120 Heidelberg, Germany
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Lin Q, Weis S, Yang G, Weng YH, Helston R, Rish K, Smith A, Bordner J, Polte T, Gaunitz F, Dennery PA. Heme oxygenase-1 protein localizes to the nucleus and activates transcription factors important in oxidative stress. J Biol Chem 2007; 282:20621-33. [PMID: 17430897 DOI: 10.1074/jbc.m607954200] [Citation(s) in RCA: 327] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is an integral membrane protein of the smooth endoplasmic reticulum. However, we detected an HO-1 immunoreactive signal in the nucleus of cultured cells after exposure to hypoxia and heme or heme/hemopexin. Under these conditions, a faster migrating HO-1 immunoreactive band was enriched in nuclear extracts, suggesting that HO-1 was cleaved to allow nuclear entry. This was confirmed by the absence of immunoreactive signal with an antibody against the C terminus and the lack of a C-terminal sequence by gas chromatographymass spectrometry. Incubation with leptomycin B prior to hypoxia abolished nuclear HO-1 and the faster migrating band on Western analysis, suggesting that this process was facilitated by CRM1. Furthermore, preincubation with a cysteine protease inhibitor prevented nuclear entry of green fluorescent protein-labeled HO-1, demonstrating that protease-mediated C-terminal cleavage was also necessary for nuclear transport of HO-1. Nuclear localization was also associated with reduction of HO activity. HO-1 protein, whether it was enzymatically active or not, mediated activation of oxidant-responsive transcription factors, including activator protein-1. Nevertheless, nuclear HO-1 protected cells against hydrogen peroxide-mediated injury equally as well as cytoplasmic HO-1. We speculate that nuclear localization of HO-1 protein may serve to up-regulate genes that promote cytoprotection against oxidative stress.
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Affiliation(s)
- Qing Lin
- Children's Hospital of Philadelphia and Department of Pediatrics, University of Pennsylvania, Philadelphia, PA 19104, USA
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40
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Kakimoto S, Moriyama T, Tanabe T, Shinkai S, Nagasaki T. Dual-ligand effect of transferrin and transforming growth factor alpha on polyethyleneimine-mediated gene delivery. J Control Release 2007; 120:242-9. [PMID: 17574290 DOI: 10.1016/j.jconrel.2007.05.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 04/21/2007] [Accepted: 05/01/2007] [Indexed: 10/23/2022]
Abstract
In order to enhance the internalization of exogenous gene and add cell specificity to non-viral vectors, receptor-binding elements have been widely utilized to mimic the virus infection. Herein, for the purpose of intensifying the effects of the ligand on gene delivery, dual receptor-binding elements, transferrin (Tf) and transforming growth factor alpha (TGFalpha), were introduced into the polyethyleneimine polyplex. The transfection and internalization efficiency by dual Tf- and TGFalpha-introduced polyplex (Tf&TGFalpha-polyplex) was examined in A549 and CHO-K1 cells, respectively. In A549, Tf&TGFalpha-polyplex had higher transfection efficiency when compared to that by single Tf- or TGFalpha-introduced polyplex (Tf-polyplex and TGFalpha-polyplex), respectively, while no enhancement was observed in CHO-K1. Moreover, in A549, the internalization efficiency of dual Tf&TGFalpha-polyplex was higher than that of single Tf- and TGFalpha-polyplex. In contrast, in CHO-K1, no difference in internalization efficiency was observed. In the presence of excess free transferrin or TGFalpha, the internalization efficiency of Tf&TGFalpha-polyplex was strongly inhibited only in A549, not in CHO-K1. In summary, the enhancement of internalization efficiency by dual ligands is an important factor for improving transfection efficiency. In addition, the effect of dual ligands depends on cell species; receptor-mediated and efficient internalization may be related to this enhanced transfection efficiency.
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Affiliation(s)
- Shinji Kakimoto
- Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka, Japan
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Tsuji T, Sheehy N, Gautier VW, Hayakawa H, Sawa H, Hall WW. The nuclear import of the human T lymphotropic virus type I (HTLV-1) tax protein is carrier- and energy-independent. J Biol Chem 2007; 282:13875-83. [PMID: 17344183 DOI: 10.1074/jbc.m611629200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
HTLV-1 is the etiologic agent of the adult T cell leukemialymphoma (ATLL). The viral regulatory protein Tax plays a central role in leukemogenesis as a transcriptional transactivator of both viral and cellular gene expression, and this requires Tax activity in both the cytoplasm and the nucleus. In the present study, we have investigated the mechanisms involved in the nuclear localization of Tax. Employing a GFP fusion expression system and a range of Tax mutants, we could confirm that the N-terminal 60 amino acids, and specifically residues within the zinc finger motif in this region, are important for nuclear localization. Using an in vitro nuclear import assay, it could be demonstrated that the transportation of Tax to the nucleus required neither energy nor carrier proteins. Specific and direct binding between Tax and p62, a nucleoporin with which the importin beta family of proteins have been known to interact was also observed. The nuclear import activity of wild type Tax and its mutants and their binding affinity for p62 were also clearly correlated, suggesting that the entry of Tax into the nucleus involves a direct interaction with nucleoporins within the nuclear pore complex (NPC). The nuclear export of Tax was also shown to be carrier independent. It could be also demonstrated that Tax it self may have a carrier function and that the NF-kappaB subunit p65 could be imported into the nucleus by Tax. These studies suggest that Tax could alter the nucleocytoplasmic distribution of cellular proteins, and this could contribute to the deregulation of cellular processes observed in HTLV-1 infection.
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Affiliation(s)
- Takahiro Tsuji
- Centre for Research in Infectious Disease, School of Medicine & Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
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Nakahara S, Oka N, Wang Y, Hogan V, Inohara H, Raz A. Characterization of the nuclear import pathways of galectin-3. Cancer Res 2006; 66:9995-10006. [PMID: 17047062 DOI: 10.1158/0008-5472.can-06-1772] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Galectin-3 (Gal-3), a pleiotropic beta-galactoside-binding protein, was shown to be involved in several nuclear-dependent functions, including up-regulation of transcriptional factors, RNA processing, and cell cycle regulation. Gal-3 compartmentalization in the nucleus versus the cytoplasm affects, in part, the malignant phenotype of various cancers. However, to date, the mechanism by which Gal-3 translocates into the nucleus remains debatable. Thus, we have constructed and expressed a variety of fusion proteins containing deletion mutants of Gal-3 fused with monomers, dimers, and trimers of enhanced green fluorescent protein and searched for the Gal-3 sequence motifs essential for its nuclear localization in vivo. In addition, a digitonin-permeabilized, cell-free transport in vitro assay was used to directly examine the mechanism of Gal-3 nuclear import. Partial deletions of the COOH-terminal region (114-250) of the human Gal-3 significantly decreases its nuclear translocation, whereas a peptide (1-115) was transported to the nuclei. The in vitro nuclear import assay revealed that there are at least two independent nuclear pathways for shuttling Gal-3 into the nucleus: a passive diffusion and an active transport. This is the first article providing direct evidence for the nuclear import mechanisms of Gal-3 and suggests that Gal-3 nuclear translocation is governed by dual pathways, whereas the cytoplasmic/nuclear distribution may be regulated by multiple processes, including cytoplasmic anchorage, nuclear retention, and or nuclear export. These results may lead to the development of a therapeutic modality aiming at abrogating Gal-3 translocation into the nucleus and thus hampering its activity during cancer progression and metastasis.
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Affiliation(s)
- Susumu Nakahara
- Tumor Progression and Metastasis Program, Karmanos Cancer Institute, Wayne State University, Detroit, Michigan 48201, USA
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Abstract
Although many components and reaction steps necessary for bidirectional transport across the nuclear envelope (NE) have been characterized, the mechanism and control of cargo migration through nuclear pore complexes (NPCs) remain poorly understood. Single-molecule fluorescence microscopy was used to track the movement of cargos before, during, and after their interactions with NPCs. At low importin β concentrations, about half of the signal-dependent cargos that interacted with an NPC were translocated across the NE, indicating a nuclear import efficiency of ∼50%. At high importin β concentrations, the import efficiency increased to ∼80% and the transit speed increased approximately sevenfold. The transit speed and import efficiency of a signal-independent cargo was also increased by high importin β concentrations. These results demonstrate that maximum nucleocytoplasmic transport velocities can be modulated by at least ∼10-fold by the importin β concentration and therefore suggest a potential mechanism for regulating the speed of cargo traffic across the NE.
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Affiliation(s)
- Weidong Yang
- Department of Molecular and Cellular Medicine, The Texas A&M University System Health Science Center, College Station, TX 77843, USA
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Kurisaki A, Kurisaki K, Kowanetz M, Sugino H, Yoneda Y, Heldin CH, Moustakas A. The mechanism of nuclear export of Smad3 involves exportin 4 and Ran. Mol Cell Biol 2006; 26:1318-32. [PMID: 16449645 PMCID: PMC1367208 DOI: 10.1128/mcb.26.4.1318-1332.2006] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Transforming growth factor beta (TGF-beta) receptors phosphorylate Smad3 and induce its nuclear import so it can regulate gene transcription. Smad3 can return to the cytoplasm to propagate further cycles of signal transduction or to be degraded. We demonstrate that Smad3 is exported by a constitutive mechanism that is insensitive to leptomycin B. The Mad homology 2 (MH2) domain is responsible for Smad3 export, which requires the GTPase Ran. Inactive, GDP-locked RanT24N or nuclear microinjection of Ran GTPase activating protein 1 blocked Smad3 export. Inactivation of the Ran guanine nucleotide exchange factor RCC1 inhibited Smad3 export and led to nuclear accumulation of phosphorylated Smad3. A screen for importin/exportin family members that associate with Smad3 identified exportin 4, which binds a conserved peptide sequence in the MH2 domain of Smad3 in a Ran-dependent manner. Exportin 4 is sufficient for carrying the in vitro nuclear export of Smad3 in cooperation with Ran. Knockdown of endogenous exportin 4 completely abrogates the export of endogenous Smad3. A short peptide representing the minimal interaction domain in Smad3 effectively competes with Smad3 association to exportin 4 and blocks nuclear export of Smad3 in vivo. We thus delineate a novel nuclear export pathway for Smad3.
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Affiliation(s)
- Akira Kurisaki
- Ludwig Institute for Cancer Research, Box 595 Biomedical Center, SE-751 24 Uppsala, Sweden
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Fukuhara T, Sakaguchi N, Katahira J, Yoneda Y, Ogino K, Tachibana T. Functional Analysis of Nuclear Pore Complex Protein Nup62/p62 Using Monoclonal Antibodies. Hybridoma (Larchmt) 2006; 25:51-9. [PMID: 16704304 DOI: 10.1089/hyb.2006.25.51] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The nuclear pore complex (NPC) is an enormous structure embedded in the double membrane of the nuclear envelope that acts as a passageway for nucleocytoplasmic transport. The vertebrate NPC is comprised of about 30 unique proteins. Nup62/p62, a major component of the NPC, has been reported to interact directly with several nuclear transport factors, including importin-beta and NTF2. However, it has not been shown how the interaction of Nup62/p62 with transport factors is involved in nucleocytoplasmic transport. The present study reports on the preparation of monoclonal antibodies (MAbs) directed against human Nup62/p62 and a functional analysis of Nup62/p62 using antibodies in living cells. Hybridomas producing the antibodies were produced by the hybridization of mouse myeloma cells with medial iliac lymph node cells from an immunized rat. These MAbs specifically recognized Nup62/p62 as evidenced by immunoblotting analysis using a nuclear membrane fraction. In the immunostaining using MAbs, a punctuate nuclear rim staining pattern was observed. Moreover, cytoplasmic injected-anti-Nup62/p62 MAbs were rapidly targeted to the nuclear pore of cultured cells and some of them inhibited normal cell division, causing the formation of abnormal nuclei. The antibodies described in this study provide the means for immunochemical analyses of the NPC protein Nup62/p62 in mammalian cells, and represent useful molecular tools that should permit a better understanding of the biological roles and cellular dynamics of this protein in nucleocytoplasmic transport, cell division, and nuclear organization.
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Affiliation(s)
- Takaomi Fukuhara
- Department of Bioengineering, Graduate School of Engineering, Osaka City University, Sugimoto, Osaka, Japan
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Yasuda Y, Miyamoto Y, Saiwaki T, Yoneda Y. Mechanism of the stress-induced collapse of the Ran distribution. Exp Cell Res 2006; 312:512-20. [PMID: 16368437 DOI: 10.1016/j.yexcr.2005.11.017] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 10/28/2005] [Accepted: 11/11/2005] [Indexed: 11/17/2022]
Abstract
The small GTPase Ran plays a central role in several key nuclear functions, including nucleocytoplasmic transport, cell cycle progression, and assembly of the nuclear envelope. In a previous study, we showed that cellular stress induces the nuclear accumulation of importin alpha, and that this appears to be triggered by a collapse in the Ran gradient, leading to the down-regulation of classical nuclear transport. We report here that a decrease in stress-induced ATP is associated with an increase in cytoplasmic Ran levels. A luciferin-luciferase assay showed that cellular stress decreased the intracellular levels of ATP. Treatment of the cells with ATP-depleting agents altered the distribution of Ran. Furthermore, when exogenous ATP was introduced in oxidative stress-treated cells, a normal distribution of Ran was restored. In addition, a pull-down experiment with an importin beta1 variant that binds to RanGTP showed that oxidative stress was accompanied by a decrease in intracellular RanGTP levels. These findings indicate that the decrease in ATP levels induced by cellular stress causes a decrease in RanGTP levels and a collapse of Ran distribution.
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Affiliation(s)
- Yoshinari Yasuda
- Department of Frontier Biosciences, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan
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Madrid AS, Weis K. Nuclear transport is becoming crystal clear. Chromosoma 2006; 115:98-109. [PMID: 16421734 DOI: 10.1007/s00412-005-0043-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 12/02/2005] [Accepted: 12/07/2005] [Indexed: 10/25/2022]
Affiliation(s)
- Alexis S Madrid
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720-3200, USA
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Isgro TA, Schulten K. Binding Dynamics of Isolated Nucleoporin Repeat Regions to Importin-β. Structure 2005; 13:1869-79. [PMID: 16338415 DOI: 10.1016/j.str.2005.09.007] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 08/31/2005] [Accepted: 09/01/2005] [Indexed: 11/24/2022]
Abstract
The nuclear pore complex, through the interaction of its proteins with transport receptors, controls the transport of large molecules into and out of the cell's nucleus. There is ample evidence for proteins with FG sequence repeats playing an essential role in this control. Previous studies have elucidated binding spots for FG sequence repeats on the surface of the transport receptor importin-beta by X-ray crystallography and mutational studies. Molecular dynamics simulations have been performed to characterize the interaction of FG sequence repeats with the transport receptor. Observed binding spots have been verified and novel sites discovered, suggesting that importin-beta features many more binding spots than suspected so far. The observed binding spots are in accord with several models of nucleocytoplasmic transport, and the large number of binding spots on importin-beta may be necessary for the pore complex to distinguish between importin-beta and inert proteins, and to allow for its passage through the pore.
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Affiliation(s)
- Timothy A Isgro
- Department of Physics, University of Illinois at Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801, USA
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Abstract
The separation of transcription in the nucleus and translation in the cytoplasm requires nucleo-cytoplasmic exchange of proteins and RNAs. Viruses have evolved strategies to capitalize on the nucleo-cytoplasmic trafficking machinery of the cell. Here, we first discuss the principal mechanisms of receptor-mediated nuclear import of proteinaceous cargo through the nuclear pore complex, the gate keeper of the cell nucleus. We then focus on viral strategies leading to nuclear import of genomes and subgenomic particles. Nucleo-cytoplasmic transport is directly important for those viruses that are replicating in the nucleus, such as DNA tumor viruses and RNA viruses, including parvoviruses, the DNA retroviruses hepadnaviruses, RNA-retrotransposons and retroviruses, adenoviruses, herpesviruses, papovaviruses, and particular negative-sense RNA viruses, such as the orthomyxovirus influenza virus. The viral strategies of nuclear import turn out to be surprisingly diverse. Their investigation continues to give insight into how nucleic acids pass in and out of the nucleus.
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Affiliation(s)
- U F Greber
- Zoologisches Institut der Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
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50
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Kose S, Furuta M, Koike M, Yoneda Y, Imamoto N. The 70-kD heat shock cognate protein (hsc70) facilitates the nuclear export of the import receptors. ACTA ACUST UNITED AC 2005; 171:19-25. [PMID: 16203861 PMCID: PMC2171223 DOI: 10.1083/jcb.200506074] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transport receptors of the importin beta family continuously shuttle between the nucleus and cytoplasm. We previously reported that the nuclear export of importin beta involves energy-requiring step(s) in living cells. Here, we show that the in vitro nuclear export of importin beta also requires energy input. Cytosol, depleted of ATP-binding proteins, did not support the sufficient nuclear export of importin beta. Further purification revealed that the active component in the absorbed fraction was a 70-kD heat shock cognate protein (hsc70). The addition of recombinant hsc70, but not an ATPase-deficient hsc70 mutant, to the depleted cytosol restored the export activity. In living cells, depletion of hsc70 caused the significant nuclear accumulation of importin beta. These effects of hsc70 were observed in the nuclear export of importin beta, but also for other import receptors, transportin and importin alpha. These results suggest that hsc70 broadly modulates nucleocytoplasmic transport systems by regulating the nuclear export of receptor proteins.
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Affiliation(s)
- Shingo Kose
- Cellular Dynamics Laboratory, Discovery Research Institute, RIKEN, Wako, Saitama 351-0198, Japan
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