1
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Casares L, Moreno R, Ali KX, Higgins M, Dayalan Naidu S, Neill G, Cassin L, Kiib AE, Svenningsen EB, Minassi A, Honda T, Poulsen TB, Wiel C, Sayin VI, Dinkova-Kostova AT, Olagnier D, de la Vega L. The synthetic triterpenoids CDDO-TFEA and CDDO-Me, but not CDDO, promote nuclear exclusion of BACH1 impairing its activity. Redox Biol 2022; 51:102291. [PMID: 35313207 PMCID: PMC8938334 DOI: 10.1016/j.redox.2022.102291] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/09/2022] [Accepted: 03/15/2022] [Indexed: 12/31/2022] Open
Abstract
The transcription factor BACH1 is a potential therapeutic target for a variety of chronic conditions linked to oxidative stress and inflammation, as well as cancer metastasis. However, only a few BACH1 degraders/inhibitors have been described. BACH1 is a transcriptional repressor of heme oxygenase 1 (HMOX1), which is positively regulated by transcription factor NRF2 and is highly inducible by derivatives of the synthetic oleanane triterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO). Most of the therapeutic activities of these compounds are due to their anti-inflammatory and antioxidant properties, which are widely attributed to their ability to activate NRF2. However, with such a broad range of action, these compounds have other molecular targets that have not been fully identified and could also be of importance for their therapeutic profile. Herein we identified BACH1 as a target of two CDDO-derivatives (CDDO-Me and CDDO-TFEA), but not of CDDO. While both CDDO and CDDO-derivatives activate NRF2 similarly, only CDDO-Me and CDDO-TFEA inhibit BACH1, which explains the much higher potency of these CDDO-derivatives as HMOX1 inducers compared with unmodified CDDO. Notably, we demonstrate that CDDO-Me and CDDO-TFEA inhibit BACH1 via a novel mechanism that reduces BACH1 nuclear levels while accumulating its cytoplasmic form. In an in vitro model, both CDDO-derivatives impaired lung cancer cell invasion in a BACH1-dependent and NRF2-independent manner, while CDDO was inactive. Altogether, our study identifies CDDO-Me and CDDO-TFEA as dual KEAP1/BACH1 inhibitors, providing a rationale for further therapeutic uses of these drugs.
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Affiliation(s)
- Laura Casares
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, UK
| | - Rita Moreno
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, UK
| | - Kevin X Ali
- Institute of Clinical Sciences, Department of Surgery, Sahlgrenska Center for Cancer Research, University of Gothenburg, Gothenburg, Sweden; Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Maureen Higgins
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, UK
| | - Sharadha Dayalan Naidu
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, UK
| | - Graham Neill
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, UK
| | - Lena Cassin
- Department of Biomedicine, Health, Aarhus University, 8000, Denmark
| | | | | | - Alberto Minassi
- Department of Drug Science, University of Piemonte Orientale, Novara, Italy
| | - Tadashi Honda
- Department of Chemistry and Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, NY, 11794-3400, USA
| | | | - Clotilde Wiel
- Institute of Clinical Sciences, Department of Surgery, Sahlgrenska Center for Cancer Research, University of Gothenburg, Gothenburg, Sweden; Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Volkan I Sayin
- Institute of Clinical Sciences, Department of Surgery, Sahlgrenska Center for Cancer Research, University of Gothenburg, Gothenburg, Sweden; Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Albena T Dinkova-Kostova
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, UK
| | - David Olagnier
- Department of Biomedicine, Health, Aarhus University, 8000, Denmark
| | - Laureano de la Vega
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, School of Medicine, University of Dundee, UK.
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2
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Lacasse V, Beaudoin S, Jean S, Leyton JV. A Novel Proteomic Method Reveals NLS Tagging of T-DM1 Contravenes Classical Nuclear Transport in a Model of HER2-Positive Breast Cancer. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 19:99-119. [PMID: 33024794 PMCID: PMC7522293 DOI: 10.1016/j.omtm.2020.08.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 08/27/2020] [Indexed: 11/01/2022]
Abstract
The next breakthrough for protein therapeutics is effective intracellular delivery and accumulation within target cells. Nuclear localization signal (NLS)-tagged therapeutics have been hindered by the lack of efficient nuclear localization due to endosome entrapment. Although development of strategies for tagging therapeutics with technologies capable of increased membrane penetration has resulted in proportional increased potency, nonspecific membrane penetration limits target specificity and, hence, widespread clinical success. There is a long-standing idea that nuclear localization of NLS-tagged agents occurs exclusively via classical nuclear transport. In the present study, we modified the antibody-drug conjugate trastuzumab-emtansine (T-DM1) with a classical NLS linked to cholic acid (cell accumulator [Accum]) that enables modified antibodies to escape endosome entrapment and increase nuclear localization efficiency without abrogating receptor targeting. In parallel, we developed a proteomics-based method to evaluate nuclear transport. Accum-modified T-DM1 significantly enhanced cytotoxic efficacy in the human epidermal growth factor receptor 2 (HER2)-positive SKBR3 breast cancer system. We discovered that efficacy was dependent on the nonclassical importin-7. Our evaluation reveals that when multiple classical NLS tagging occurs, cationic charge build-up as opposed to sequence dominates and becomes a substrate for importin-7. This study results in an effective target cell-specific NLS therapeutic and a general approach to guide future NLS-based development initiatives.
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Affiliation(s)
- Vincent Lacasse
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Centre Hospitalier Universitaire de Sherbrooke (CHUS), Université de Sherbrooke (UdeS), Sherbrooke, QC J1H 5N4, Canada
| | - Simon Beaudoin
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Centre Hospitalier Universitaire de Sherbrooke (CHUS), Université de Sherbrooke (UdeS), Sherbrooke, QC J1H 5N4, Canada
| | - Steve Jean
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, CHUS, UdeS, Sherbrooke, QC J1H 5N4, Canada
| | - Jeffrey V Leyton
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Centre Hospitalier Universitaire de Sherbrooke (CHUS), Université de Sherbrooke (UdeS), Sherbrooke, QC J1H 5N4, Canada.,Sherbrooke Molecular Imaging Centre (CIMS), Centre de Recherche du CHUS, UdeS, Sherbrooke, QC J1H 5N4, Canada
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3
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Lin CY, Lin LY. The conserved basic residues and the charged amino acid residues at the α-helix of the zinc finger motif regulate the nuclear transport activity of triple C2H2 zinc finger proteins. PLoS One 2018; 13:e0191971. [PMID: 29381770 PMCID: PMC5790263 DOI: 10.1371/journal.pone.0191971] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 01/15/2018] [Indexed: 11/19/2022] Open
Abstract
Zinc finger (ZF) motifs on proteins are frequently recognized as a structure for DNA binding. Accumulated reports indicate that ZF motifs contain nuclear localization signal (NLS) to facilitate the transport of ZF proteins into nucleus. We investigated the critical factors that facilitate the nuclear transport of triple C2H2 ZF proteins. Three conserved basic residues (hot spots) were identified among the ZF sequences of triple C2H2 ZF proteins that reportedly have NLS function. Additional basic residues can be found on the α-helix of the ZFs. Using the ZF domain (ZFD) of Egr-1 as a template, various mutants were constructed and expressed in cells. The nuclear transport activity of various mutants was estimated by analyzing the proportion of protein localized in the nucleus. Mutation at any hot spot of the Egr-1 ZFs reduced the nuclear transport activity. Changes of the basic residues at the α-helical region of the second ZF (ZF2) of the Egr-1 ZFD abolished the NLS activity. However, this activity can be restored by substituting the acidic residues at the homologous positions of ZF1 or ZF3 with basic residues. The restored activity dropped again when the hot spots at ZF1 or the basic residues in the α-helix of ZF3 were mutated. The variations in nuclear transport activity are linked directly to the binding activity of the ZF proteins with importins. This study was extended to other triple C2H2 ZF proteins. SP1 and KLF families, similar to Egr-1, have charged amino acid residues at the second (α2) and the third (α3) positions of the α-helix. Replacing the amino acids at α2 and α3 with acidic residues reduced the NLS activity of the SP1 and KLF6 ZFD. The reduced activity can be restored by substituting the α3 with histidine at any SP1 and KLF6 ZFD. The results show again the interchangeable role of ZFs and charge residues in the α-helix in regulating the NLS activity of triple C2H2 ZF proteins.
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Affiliation(s)
- Chih-Ying Lin
- Institute of Molecular and Cellular Biology and Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan, ROC
| | - Lih-Yuan Lin
- Institute of Molecular and Cellular Biology and Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan, ROC
- * E-mail:
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4
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Yagai T, Matsui S, Harada K, Inagaki FF, Saijou E, Miura Y, Nakanuma Y, Miyajima A, Tanaka M. Expression and localization of sterile alpha motif domain containing 5 is associated with cell type and malignancy of biliary tree. PLoS One 2017; 12:e0175355. [PMID: 28388653 PMCID: PMC5384680 DOI: 10.1371/journal.pone.0175355] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/07/2017] [Indexed: 12/15/2022] Open
Abstract
Cholangiocarcinoma (CC) is a type of relatively rare neoplasm in adenocarcinoma. The characteristics of CCs as well as biliary epithelial cells are heterogeneous at the different portion of the biliary tree. There are two candidate stem/progenitor cells of the biliary tree, i.e., biliary tree stem/progenitor cell (BTSC) at the peribiliary gland (PBG) of large bile ducts and liver stem/progenitor cell (LPC) at the canals of Hering of peripheral small bile duct. Although previous reports suggest that intrahepatic CC (ICC) can arise from such stem/progenitor cells, the characteristic difference between BTSC and LPC in pathological process needs further investigation, and the etiology of CC remains poorly understood. Here we show that Sterile alpha motif domain containing 5 (SAMD5) is exclusively expressed in PBGs of large bile ducts in normal mice. Using a mouse model of cholestatic liver disease, we demonstrated that SAMD5 expression was upregulated in the large bile duct at the hepatic hilum, the extrahepatic bile duct and PBGs, but not in proliferating intrahepatic ductules, suggesting that SAMD5 is expressed in BTSC but not LPC. Intriguingly, human ICCs and extrahepatic CCs exhibited striking nuclear localization of SAMD5 while the normal hilar large bile duct displayed slight-to-moderate expression in cytoplasm. In vitro experiments using siRNA for SAMD5 revealed that SAMD5 expression was associated with the cell cycle regulation of CC cell lines. Conclusion: SAMD5 is a novel marker for PBG but not LPC in mice. In humans, the expression and location of SAMD5 could become a promising diagnostic marker for the cell type as well as malignancy of bile ducts and CCs.
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Affiliation(s)
- Tomoki Yagai
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Satoshi Matsui
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Kenichi Harada
- Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan
| | - Fuyuki F. Inagaki
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Eiko Saijou
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Yasushi Miura
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
- Department of Life Science and Medical Bio-Science, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Yasuni Nakanuma
- Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan
| | - Atsushi Miyajima
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Minoru Tanaka
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
- Laboratory of Stem Cell Regulation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
- * E-mail:
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5
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Baas R, Sijm A, van Teeffelen HAAM, van Es R, Vos HR, Marc Timmers HT. Quantitative Proteomics of the SMAD (Suppressor of Mothers against Decapentaplegic) Transcription Factor Family Identifies Importin 5 as a Bone Morphogenic Protein Receptor SMAD-specific Importin. J Biol Chem 2016; 291:24121-24132. [PMID: 27703004 DOI: 10.1074/jbc.m116.748582] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 10/03/2016] [Indexed: 01/11/2023] Open
Abstract
Gene-specific transcription factors (GSTFs) control gene transcription by DNA binding and specific protein complex recruitment, which regulates promoter accessibility for transcription initiation by RNA polymerase II. Mutations in the GSTFs Suppressor of Mothers Against Decapentaplegic 2 (SMAD2) and SMAD4 are frequently associated with colon and rectal carcinomas. These proteins play an important role in bone morphogenic protein (BMP) and transforming growth factor β (TGF-β) signaling pathways controlling cell fate and proliferation. To study the protein interactome of the SMAD protein family we generated a quantitative proteomics pipeline that allows for inducible expression of GFP-tagged SMAD proteins followed by affinity purification and quantitative mass spectrometry analysis. Data are available via ProteomeXchange with identifier PXD004529. The nuclear importin IPO5 was identified as a novel interacting protein of SMAD1. Overexpression of IPO5 in various cell lines specifically increases nuclear localization of BMP receptor-activated SMADs (R-SMADs) confirming a functional relationship between IPO5 and BMP but not TGF-β R-SMADs. Finally, we provide evidence that variation in length of the lysine stretch of the nuclear localization sequence is a determinant for importin specificity.
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Affiliation(s)
- Roy Baas
- From the Departments of Molecular Cancer Research and Stem Cells, Regenerative Medicine Center, Center for Molecular Medicine, University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Ayestha Sijm
- From the Departments of Molecular Cancer Research and Stem Cells, Regenerative Medicine Center, Center for Molecular Medicine, University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Hetty A A M van Teeffelen
- From the Departments of Molecular Cancer Research and Stem Cells, Regenerative Medicine Center, Center for Molecular Medicine, University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Robert van Es
- From the Departments of Molecular Cancer Research and Stem Cells, Regenerative Medicine Center, Center for Molecular Medicine, University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Harmjan R Vos
- From the Departments of Molecular Cancer Research and Stem Cells, Regenerative Medicine Center, Center for Molecular Medicine, University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - H Th Marc Timmers
- From the Departments of Molecular Cancer Research and Stem Cells, Regenerative Medicine Center, Center for Molecular Medicine, University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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6
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Suárez-Sánchez R, Aguilar A, Wagstaff KM, Velez G, Azuara-Medina PM, Gomez P, Vásquez-Limeta A, Hernández-Hernández O, Lieu KG, Jans DA, Cisneros B. Nucleocytoplasmic shuttling of the Duchenne muscular dystrophy gene product dystrophin Dp71d is dependent on the importin α/β and CRM1 nuclear transporters and microtubule motor dynein. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1843:985-1001. [PMID: 24486332 DOI: 10.1016/j.bbamcr.2014.01.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 12/17/2013] [Accepted: 01/24/2014] [Indexed: 01/08/2023]
Abstract
Even though the Duchenne muscular dystrophy (DMD) gene product Dystrophin Dp71d is involved in various key cellular processes through its role as a scaffold for structural and signalling proteins at the plasma membrane as well as the nuclear envelope, its subcellular trafficking is poorly understood. Here we map the nuclear import and export signals of Dp71d by truncation and point mutant analysis, showing for the first time that Dp71d shuttles between the nucleus and cytoplasm mediated by the conventional nuclear transporters, importin (IMP) α/β and the exportin CRM1. Binding was confirmed in cells using pull-downs, while in vitro binding assays showed direct, high affinity (apparent dissociation coefficient of c. 0.25nM) binding of Dp71d to IMPα/β. Interestingly, treatment of cells with the microtubule depolymerizing reagent nocodazole or the dynein inhibitor EHNA both decreased Dp71d nuclear localization, implying that Dp71d nuclear import may be facilitated by microtubules and the motor protein dynein. The role of Dp71d in the nucleus appears to relate in part to interaction with the nuclear envelope protein emerin, and maintenance of the integrity of the nuclear architecture. The clear implication is that Dp71d's previously unrecognised nuclear transport properties likely contribute to various, important physiological roles.
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Affiliation(s)
- R Suárez-Sánchez
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico; Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México D.F, Mexico
| | - A Aguilar
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - K M Wagstaff
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - G Velez
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - P M Azuara-Medina
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - P Gomez
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - A Vásquez-Limeta
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - O Hernández-Hernández
- Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México D.F, Mexico
| | - K G Lieu
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - D A Jans
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia.
| | - B Cisneros
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico.
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7
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Frohnert C, Hutten S, Wälde S, Nath A, Kehlenbach RH. Importin 7 and Nup358 promote nuclear import of the protein component of human telomerase. PLoS One 2014; 9:e88887. [PMID: 24586428 PMCID: PMC3930611 DOI: 10.1371/journal.pone.0088887] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 01/13/2014] [Indexed: 01/18/2023] Open
Abstract
In actively dividing eukaryotic cells, chromosome ends (telomeres) are subject to progressive shortening, unless they are maintained by the action of telomerase, a dedicated enzyme that adds DNA sequence repeats to chromosomal 3′end. For its enzymatic function on telomeres, telomerase requires nuclear import of its protein component (hTERT in human cells) and assembly with the RNA component, TERC. We now confirm a major nuclear localization signal (NLS) in the N-terminal region of hTERT and describe a novel one in the C-terminal part. Using an siRNA approach to deplete several import receptors, we identify importin 7 as a soluble nuclear transport factor that is required for efficient import. At the level of the nuclear pore complex (NPC), Nup358, a nucleoporin that forms the cytoplasmic filaments of the NPC, plays an important role in nuclear import of hTERT. A structure-function analysis of Nup358 revealed that the zinc finger region of the nucleoporin is of particular importance for transport of hTERT. Together, our study sheds light on the nuclear import pathway of hTERT.
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Affiliation(s)
- Cornelia Frohnert
- Institute of Molecular Biology, Faculty of Medicine, University of Göttingen, Göttingen, Germany
| | - Saskia Hutten
- Institute of Molecular Biology, Faculty of Medicine, University of Göttingen, Göttingen, Germany
| | - Sarah Wälde
- Institute of Molecular Biology, Faculty of Medicine, University of Göttingen, Göttingen, Germany
| | - Annegret Nath
- Institute of Molecular Biology, Faculty of Medicine, University of Göttingen, Göttingen, Germany
| | - Ralph H. Kehlenbach
- Institute of Molecular Biology, Faculty of Medicine, University of Göttingen, Göttingen, Germany
- * E-mail:
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8
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Beta-like importins mediate the nuclear translocation of mitogen-activated protein kinases. Mol Cell Biol 2013; 34:259-70. [PMID: 24216760 DOI: 10.1128/mcb.00799-13] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The rapid nuclear translocation of signaling proteins upon stimulation is important for the regulation of de novo gene expression. We have studied the stimulated nuclear shuttling of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs) and found that they translocate into the nucleus in a Ran-dependent, but NLS- or NTS-independent, manner, unrelated to their catalytic activity. We show that this translocation involves three β-like importins, importins 3, 7, and 9 (Imp3/7/9). Knockdown of these importins inhibits the nuclear translocation of the MAPKs and, thereby, activation of their transcription factor targets. We further demonstrate that the translocation requires the stimulated formation of heterotrimers composed of Imp3/Imp7/MAPK or Imp3/Imp9/MAPK. JNK1/2 and p38α/β bind to either Imp7 or Imp9 upon stimulated posttranslational modification of the two Imps, while Imp3 joins the complex after its stimulation-induced phosphorylation. Once formed, these heterotrimers move to the nuclear envelope, where importin 3 remains, while importins 7 and 9 escort the MAPKs into the nucleus. These results suggest that β-like importins are central mediators of stimulated nuclear translocation of signaling proteins and therefore add a central level of regulation to stimulated transcription.
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9
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Androgen induces a switch from cytoplasmic retention to nuclear import of the androgen receptor. Mol Cell Biol 2013; 33:4766-78. [PMID: 24100013 DOI: 10.1128/mcb.00647-13] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The androgen receptor (AR) has critical functions as a transcription factor in both normal and cancer cells, but the specific mechanisms that regulate its nuclear localization are not well defined. We found that an AR mutation commonly reported in prostate cancer generates an androgen-independent gain of function for nuclear import. The substitution, Thr877Ala, is within the ligand-binding domain, but the nuclear import gain of function is mediated by the bipartite nuclear localization signal (NLS) spanning the DNA-binding domain (DBD) and hinge region. Bipartite NLS activity depends on the structure provided by the DBD, and protein interactions with the bipartite NLS are repressed by the hinge region. The bipartite NLS is recognized by importin 7, a nuclear import receptor for several proteins. Importin 7 binding to AR, however, inhibits import by shielding the bipartite NLS. Androgen binding relieves the inhibition by inducing a switch that promotes exchange of importin 7 for karyopherin alpha import receptors. Importin 7 contributes to the regulation of AR import by restraining import until androgen is detected in the cytoplasm.
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10
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Roloff S, Spillner C, Kehlenbach RH. Several phenylalanine-glycine motives in the nucleoporin Nup214 are essential for binding of the nuclear export receptor CRM1. J Biol Chem 2013; 288:3952-63. [PMID: 23264634 PMCID: PMC3567648 DOI: 10.1074/jbc.m112.433243] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 12/12/2012] [Indexed: 02/06/2023] Open
Abstract
Nucleoporins containing phenylalanine glycine (FG) repeats play an important role in nucleocytoplasmic transport as they bind to transport receptors and mediate translocation of transport complexes across the nuclear pore complex (NPC). Nup214/CAN, a nucleoporin that is found at the cytoplasmic side of the NPC, interacts with both import and export receptors. In functional assays, dominant-negative fragments of Nup214 inhibited CRM1-dependent nuclear export, as the export receptor became rate-limiting. Several nuclear import pathways, by contrast, were not affected by the Nup214 fragments. We now characterize the CRM1-binding region of Nup214 in detail and identify several FG motives that are required for this interaction. Our results support a model where CRM1, like other transport receptors, contacts FG-Nups via multiple binding sites.
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Affiliation(s)
- Stephanie Roloff
- From the Department of Biochemistry I, Faculty of Medicine, Georg-August-University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Christiane Spillner
- From the Department of Biochemistry I, Faculty of Medicine, Georg-August-University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Ralph H. Kehlenbach
- From the Department of Biochemistry I, Faculty of Medicine, Georg-August-University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
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11
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Mehdi AM, Sehgal MSB, Kobe B, Bailey TL, Bodén M. DLocalMotif: a discriminative approach for discovering local motifs in protein sequences. ACTA ACUST UNITED AC 2012; 29:39-46. [PMID: 23142965 DOI: 10.1093/bioinformatics/bts654] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
MOTIVATION Local motifs are patterns of DNA or protein sequences that occur within a sequence interval relative to a biologically defined anchor or landmark. Current protein motif discovery methods do not adequately consider such constraints to identify biologically significant motifs that are only weakly over-represented but spatially confined. Using negatives, i.e. sequences known to not contain a local motif, can further increase the specificity of their discovery. RESULTS This article introduces the method DLocalMotif that makes use of positional information and negative data for local motif discovery in protein sequences. DLocalMotif combines three scoring functions, measuring degrees of motif over-representation, entropy and spatial confinement, specifically designed to discriminatively exploit the availability of negative data. The method is shown to outperform current methods that use only a subset of these motif characteristics. We apply the method to several biological datasets. The analysis of peroxisomal targeting signals uncovers several novel motifs that occur immediately upstream of the dominant peroxisomal targeting signal-1 signal. The analysis of proline-tyrosine nuclear localization signals uncovers multiple novel motifs that overlap with C2H2 zinc finger domains. We also evaluate the method on classical nuclear localization signals and endoplasmic reticulum retention signals and find that DLocalMotif successfully recovers biologically relevant sequence properties. AVAILABILITY http://bioinf.scmb.uq.edu.au/dlocalmotif/
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Affiliation(s)
- Ahmed M Mehdi
- Institute for Molecular Bioscience, The University of Queensland, Australia
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12
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Shen T, Liu Y, Schneider MF. Localization and regulation of the N terminal splice variant of PGC-1α in adult skeletal muscle fibers. J Biomed Biotechnol 2012; 2012:989263. [PMID: 22500113 PMCID: PMC3303705 DOI: 10.1155/2012/989263] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 10/26/2011] [Indexed: 01/30/2023] Open
Abstract
The transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) regulates expression of genes for metabolism and muscle fiber type. Recently, a novel splice variant of PGC-1α (NT-PGC-1α, amino acids 1-270) was cloned and found to be expressed in muscle. Here we use Flag-tagged NT-PGC-1α to examine the subcellular localization and regulation of NT-PGC-1α in skeletal muscle fibers. Flag-NT-PGC-1α is located predominantly in the myoplasm. Nuclear NT-PGC-1α can be increased by activation of protein kinase A. Activation of p38 MAPK by muscle activity or of AMPK had no effect on the subcellular distribution of NT-PGC-1α. Inhibition of CRM1-mediated export only caused relatively slow nuclear accumulation of NT-PGC-1α, indicating that nuclear export of NT-PGC-1α may be mediated by both CRM1-dependent and -independent pathways. Together these results suggest that the regulation of NT-PGC-1α in muscle fibers may be very different from that of the full-length PGC-1α, which is exclusively nuclear.
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Affiliation(s)
- Tiansheng Shen
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201-1503, USA
| | - Yewei Liu
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201-1503, USA
| | - Martin F. Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201-1503, USA
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13
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Golomb L, Bublik DR, Wilder S, Nevo R, Kiss V, Grabusic K, Oren M. Importin 7 and exportin 1 link c-Myc and p53 to regulation of ribosomal biogenesis. Mol Cell 2012; 45:222-32. [PMID: 22284678 PMCID: PMC3270374 DOI: 10.1016/j.molcel.2011.11.022] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 07/13/2011] [Accepted: 11/04/2011] [Indexed: 11/22/2022]
Abstract
Members of the β-karyopherin family mediate nuclear import of ribosomal proteins and export of ribosomal subunits, both required for ribosome biogenesis. We report that transcription of the β-karyopherin genes importin 7 (IPO7) and exportin 1 (XPO1), and several additional nuclear import receptors, is regulated positively by c-Myc and negatively by p53. Partial IPO7 depletion triggers p53 activation and p53-dependent growth arrest. Activation of p53 by IPO7 knockdown has distinct features of ribosomal biogenesis stress, with increased binding of Mdm2 to ribosomal proteins L5 and L11 (RPL5 and RPL11). Furthermore, p53 activation is dependent on RPL5 and RPL11. Of note, IPO7 and XPO1 are frequently overexpressed in cancer. Altogether, we propose that c-Myc and p53 counter each other in the regulation of elements within the nuclear transport machinery, thereby exerting opposing effects on the rate of ribosome biogenesis. Perturbation of this balance may play a significant role in promoting cancer.
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Affiliation(s)
- Lior Golomb
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Debora Rosa Bublik
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sylvia Wilder
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Reinat Nevo
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Vladimir Kiss
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Kristina Grabusic
- Department of Molecular medicine and Biotechnology, University of Rijeka, School of Medicine, Rijeka 51000, Croatia
| | - Moshe Oren
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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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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15
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Chook YM, Süel KE. Nuclear import by karyopherin-βs: recognition and inhibition. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:1593-606. [PMID: 21029754 DOI: 10.1016/j.bbamcr.2010.10.014] [Citation(s) in RCA: 300] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 10/06/2010] [Accepted: 10/19/2010] [Indexed: 01/24/2023]
Abstract
Proteins in the karyopherin-β family mediate the majority of macromolecular transport between the nucleus and the cytoplasm. Eleven of the 19 known human karyopherin-βs and 10 of the 14S. cerevisiae karyopherin-βs mediate nuclear import through recognition of nuclear localization signals or NLSs in their cargos. This receptor-mediated process is essential to cellular viability as proteins are translated in the cytoplasm but many have functional roles in the nucleus. Many known karyopherin-β-cargo interactions were discovered through studies of the individual cargos rather than the karyopherins, and this information is thus widely scattered in the literature. We consolidate information about cargos that are directly recognized by import-karyopherin-βs and review common characteristics or lack thereof among cargos of different import pathways. Knowledge of karyopherin-β-cargo interactions is also critical for the development of nuclear import inhibitors and the understanding of their mechanisms of inhibition. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.
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Affiliation(s)
- Yuh Min Chook
- Department of Pharmacology, University of Texas Southerwestern Medical Center, Dallas, TX 75206, USA.
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Ploski JE, Topisirovic I, Park KW, Borden KLB, Radu A. A mechanism of nucleocytoplasmic trafficking for the homeodomain protein PRH. Mol Cell Biochem 2009; 332:173-81. [PMID: 19588232 DOI: 10.1007/s11010-009-0188-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 06/25/2009] [Indexed: 11/24/2022]
Abstract
Proline-rich homeodomain (PRH)/hematopoietically expressed homeodomain (Hex) is a homeodomain protein that plays an important role in early embryonic patterning and hematopoiesis. PRH can act as either a tumor suppressor or an oncogene and its expression is dysregulated in certain types of lymphoid and myeloid leukemias. Aberrant exclusion of PRH from the nuclei has been associated with thyroid and breast cancers and a subset of myeloid leukemias. Accordingly, nuclear localization of PRH was found to be necessary for the inhibition of eIF4E-dependent transformation. Since PRH's nuclear-cytoplasmic localization has been associated with neoplastic transformation we sought to better understand how PRH is transported to the nuclear compartment. Here, we report an essential element that controls the mechanism of PRH nucleocytoplasmic trafficking, namely that it is imported into the nuclei by Karyopherin/Importin 7. Kap7 was identified as a binding partner for PRH in a GST-pull down from a HeLa cell protein lysate, followed by mass-spectrometry. The Kap7-PRH complex is dissociated in the presence of RanGTP, as expected for a nuclear import complex. Kap7 can bind directly to PRH in a GST-pull down assay with purified proteins, as well as mediates the transport of PRH to the nuclear compartment in a digitonin permeabilized cells assay. Finally, in vivo depletion of Kap7 dramatically reduces accumulation of PRH in the nucleus. Our data open the way for investigations of the mechanism of perturbed PRH localization in tumors and possible therapeutic interventions.
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Lin W, Ye W, Cai L, Meng X, Ke G, Huang C, Peng Z, Yu Y, Golden JA, Tartakoff AM, Tao T. The roles of multiple importins for nuclear import of murine aristaless-related homeobox protein. J Biol Chem 2009; 284:20428-39. [PMID: 19494118 DOI: 10.1074/jbc.m109.004242] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Nuclear import of proteins with nuclear localization signals (NLSs) is mediated by shuttling carriers, the importins. Some cargoes display more than a single NLS, and among these are homeodomain proteins such as Arx, which is critical for development of multiple tissues. Arx has two functional NLSs. The present studies show that several pathways can import Arx via its NLS2, which is within its DNA binding homeodomain. Using an in vitro nuclear import assay, we show that import of Arx via NLS2 can be mediated by importin beta1, importin 9, or importin 13, with binding being strongest to importin beta1. All binding is sensitive to RanGTP. Experiments based on precise domain deletions indicate that NLS2 binds impbeta1, imp9, and imp13 and includes both an importin binding subdomain and a regulatory subdomain with arginine residues being important for function. Moreover, Arx can be co-precipitated with these importins when NLS2 is present. Although nuclear import of Arx can be mediated by these three importin betas, importin beta1 seems to play the major role judging from in vivo small interfering RNA ablations and the in vitro import assay. This is the first evidence to show the role of importin beta1 in nuclear import of paired-type homeodomain proteins. We propose a novel and possibly quite general mechanism for nuclear import of paired-type homeodomain proteins which is critical for development.
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Affiliation(s)
- Wenbo Lin
- School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, China
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Fuller JM, Bogdani M, Tupling TD, Jensen RA, Pefley R, Manavi S, Cort L, Blankenhorn EP, Mordes JP, Lernmark A, Kwitek AE. Genetic dissection reveals diabetes loci proximal to the gimap5 lymphopenia gene. Physiol Genomics 2009; 38:89-97. [PMID: 19351909 DOI: 10.1152/physiolgenomics.00015.2009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Congenic DRF.(f/f) rats are protected from type 1 diabetes (T1D) by 34 Mb of F344 DNA introgressed proximal to the gimap5 lymphopenia gene. To dissect the genetic factor(s) that confer protection from T1D in the DRF.(f/f) rat line, DRF.(f/f) rats were crossed to inbred BBDR or DR.(lyp/lyp) rats to generate congenic sublines that were genotyped and monitored for T1D, and positional candidate genes were sequenced. All (100%) DR.(lyp/lyp) rats developed T1D by 83 days of age. Reduction of the DRF.(f/f) F344 DNA fragment by 26 Mb (42.52-68.51 Mb) retained complete T1D protection. Further dissection revealed that a 2 Mb interval of F344 DNA (67.41-70.17 Mb) (region 1) resulted in 47% protection and significantly delayed onset (P < 0.001 compared with DR.(lyp/lyp)). Retaining <1 Mb of F344 DNA at the distal end (76.49-76.83 Mb) (region 2) resulted in 28% protection and also delayed onset (P < 0.001 compared with DR.(lyp/lyp)). Comparative analysis of diabetes frequency in the DRF.(f/f) congenic sublines further refined the RNO4 region 1 interval to approximately 670 kb and region 2 to the 340 kb proximal to gimap5. All congenic DRF.(f/f) sublines were prone to low-grade pancreatic mononuclear cell infiltration around ducts and vessels, but <20% of islets in nondiabetic rats showed islet infiltration. Coding sequence analysis revealed TCR Vbeta 8E, 12, and 13 as candidate genes in region 1 and znf467 and atp6v0e2 as candidate genes in region 2. Our results show that spontaneous T1D is controlled by at least two genetic loci 7 Mb apart on rat chromosome 4.
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Affiliation(s)
- J M Fuller
- Department of Clinical Sciences, Lund University, Clinical Research Center, Malmö, Sweden.
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Zaitseva L, Cherepanov P, Leyens L, Wilson SJ, Rasaiyaah J, Fassati A. HIV-1 exploits importin 7 to maximize nuclear import of its DNA genome. Retrovirology 2009; 6:11. [PMID: 19193229 PMCID: PMC2660290 DOI: 10.1186/1742-4690-6-11] [Citation(s) in RCA: 77] [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: 12/15/2008] [Accepted: 02/04/2009] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Nuclear import of the HIV-1 reverse transcription complex (RTC) is critical for infection of non dividing cells, and importin 7 (imp7) has been implicated in this process. To further characterize the function of imp7 in HIV-1 replication we generated cell lines stably depleted for imp7 and used them in conjunction with infection, cellular fractionation and pull-down assays. RESULTS Imp7 depletion impaired HIV-1 infection but did not significantly affect HIV-2, simian immunodeficiency virus (SIVmac), or equine infectious anemia virus (EIAV). The lentiviral dependence on imp7 closely correlated with binding of the respective integrase proteins to imp7. HIV-1 RTC associated with nuclei of infected cells with remarkable speed and knock down of imp7 reduced HIV-1 DNA nuclear accumulation, delaying infection. Using an HIV-1 mutant deficient for reverse transcription, we found that viral RNA accumulated within nuclei of infected cells, indicating that reverse transcription is not absolutely required for nuclear import. Depletion of imp7 impacted on HIV-1 DNA but not RNA nuclear import and also inhibited DNA transfection efficiency. CONCLUSION Although imp7 may not be essential for HIV-1 infection, our results suggest that imp7 facilitates nuclear trafficking of DNA and that HIV-1 exploits imp7 to maximize nuclear import of its DNA genome. Lentiviruses other than HIV-1 may have evolved to use alternative nuclear import receptors to the same end.
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Affiliation(s)
- Lyubov Zaitseva
- Wohl Virion Centre, Division of Infection and Immunity, University College London (UCL), London, UK
- MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London (UCL), London, UK
| | - Peter Cherepanov
- Division of Medicine, St Mary's Campus, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - Lada Leyens
- Wohl Virion Centre, Division of Infection and Immunity, University College London (UCL), London, UK
- MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London (UCL), London, UK
| | - Sam J Wilson
- MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London (UCL), London, UK
- Centre for Post-genomic Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London, W1T 4JF, UK
| | - Jane Rasaiyaah
- MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London (UCL), London, UK
- Centre for Post-genomic Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London, W1T 4JF, UK
| | - Ariberto Fassati
- Wohl Virion Centre, Division of Infection and Immunity, University College London (UCL), London, UK
- MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London (UCL), London, UK
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Design of peptide inhibitors for the importin alpha/beta nuclear import pathway by activity-based profiling. ACTA ACUST UNITED AC 2008; 15:940-9. [PMID: 18804031 DOI: 10.1016/j.chembiol.2008.07.019] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 07/07/2008] [Accepted: 07/21/2008] [Indexed: 02/07/2023]
Abstract
Despite the current availability of selective inhibitors for the classical nuclear export pathway, no inhibitor for the classical nuclear import pathway has been developed. Here we describe the development of specific inhibitors for the importin alpha/beta pathway using a novel method of peptide inhibitor design. An activity-based profile was created via systematic mutational analysis of a peptide template of a nuclear localization signal. An additivity-based design using the activity-based profile generated two peptides with affinities for importin alpha that were approximately 5 million times higher than that of the starting template sequence. The high affinity of these peptides resulted in specific inhibition of the importin alpha/beta pathway. These peptide inhibitors provide a useful tool for studying nuclear import events. Moreover, our inhibitor design method should enable the development of potent inhibitors from a peptide seed.
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Okada N, Ishigami Y, Suzuki T, Kaneko A, Yasui K, Fukutomi R, Isemura M. Importins and exportins in cellular differentiation. J Cell Mol Med 2008; 12:1863-71. [PMID: 18657223 PMCID: PMC4506156 DOI: 10.1111/j.1582-4934.2008.00437.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The importin/exportin transport system provides the machinery involved in nucleocytoplasmic transport. Alterations of the levels of importins and exportins may play crucial roles in development, differentiation and transformation. Employing human leukaemia HL-60 cells, we and others have revealed the differentiation-associated changes in the protein and gene expression of these factors. The recent finding that a switch to the importin-α subtype triggers neural differentiation of embryonic stem cells underscores the importance of nucleocytoplasmic transport factors in cellular events. This review focuses on current research into the roles of importins and exportins in cell differentiation.
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Affiliation(s)
- Norihisa Okada
- Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan
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