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Yu Z, Islam S, She M, Diepeveen D, Zhang Y, Tang G, Zhang J, Juhasz A, Yang R, Ma W. Wheat grain protein accumulation and polymerization mechanisms driven by nitrogen fertilization. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:1160-1177. [PMID: 30230644 DOI: 10.1111/tpj.14096] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 09/07/2018] [Accepted: 09/11/2018] [Indexed: 05/09/2023]
Abstract
In wheat (Triticum aestivum) grain yield and grain protein content are negatively correlated, making the simultaneous increase of the two traits challenging. Apart from genetic approaches, modification of nitrogen fertilization offers a feasible option to achieve this aim. In this study, a range of traits related to nitrogen-use efficiency in six Australian bread wheat varieties were investigated under different nitrogen treatments using 3-year multisite field trials. Changes in the individual storage protein composition were detected by high-performance liquid chromatography. Our results indicated that wheat grain yield and grain protein content reacted similarly to nitrogen availability, with grain yield being slightly more sensitive than grain protein content, and that genotype is a vital determinant of grain protein yield. Measurement of the glutamine synthetase activity of flag leaves and developing grains revealed that high nitrogen availability prompted the participation of glutamine in biological processes. In addition, a more significant accumulation of gluten macropolymer was observed under the high-nitrogen treatment from 21 days post-anthesis, and the underlying mechanism was elucidated by a comparative proteomics study. A yeast two-hybrid experiment confirmed this mechanism. The results of this study revealed that peptidyl-prolyl cis-trans isomerase (PPIase) was SUMOylated with the assistance of small ubiquitin-related modifier 1 and that high nitrogen availability facilitated this connection for the subsequent protein polymerization. Additionally, luminal-binding protein 2 in the endoplasmic reticulum played a similar role to PPIase in the aggregation of protein under high-nitrogen conditions.
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Affiliation(s)
- Zitong Yu
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Australia-China Joint Centre for Wheat Improvement, Murdoch University, Perth, WA, 6150, Australia
| | - Shahidul Islam
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Australia-China Joint Centre for Wheat Improvement, Murdoch University, Perth, WA, 6150, Australia
| | - Maoyun She
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Australia-China Joint Centre for Wheat Improvement, Murdoch University, Perth, WA, 6150, Australia
| | - Dean Diepeveen
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Western Australian Department of Agriculture and Food, 3 Baron-Hay Ct, South Perth, WA, 6151, Australia
| | - Yujuan Zhang
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
| | - Guixiang Tang
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Australia-China Joint Centre for Wheat Improvement, Murdoch University, Perth, WA, 6150, Australia
| | - Jingjuan Zhang
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Australia-China Joint Centre for Wheat Improvement, Murdoch University, Perth, WA, 6150, Australia
| | - Angela Juhasz
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Australia-China Joint Centre for Wheat Improvement, Murdoch University, Perth, WA, 6150, Australia
| | - Rongchang Yang
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Australia-China Joint Centre for Wheat Improvement, Murdoch University, Perth, WA, 6150, Australia
| | - Wujun Ma
- State Agricultural Biotechnology Centre, School of Veterinary and Life Science, Murdoch University, Perth, WA, 6150, Australia
- Australia-China Joint Centre for Wheat Improvement, Murdoch University, Perth, WA, 6150, Australia
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202
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Nguyen T, Pappireddi N, Wühr M. Proteomics of nucleocytoplasmic partitioning. Curr Opin Chem Biol 2018; 48:55-63. [PMID: 30472625 DOI: 10.1016/j.cbpa.2018.10.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/30/2018] [Accepted: 10/31/2018] [Indexed: 12/21/2022]
Abstract
The partitioning of the proteome between nucleus and cytoplasm affects nearly every aspect of eukaryotic biology. Despite this central role, we still have a poor understanding of which proteins localize in the nucleus and how this varies in different cell types and conditions. Recent advances in quantitative proteomics and high-throughput imaging are starting to close this knowledge gap. Studies on protein interaction are beginning to reveal the spectrum of cargos of nuclear import and export receptors. We anticipate that it will soon be possible to predict each protein's nucleocytoplasmic localization based on its importin/exportin interactions and its estimated diffusion rate through the nuclear pore. This insight is likely to provide us with a fundamental understanding of how cells use nucleocytoplasmic partitioning to encode and relay information.
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Affiliation(s)
- Thao Nguyen
- Department of Molecular Biology & the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Nishant Pappireddi
- Department of Molecular Biology & the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Martin Wühr
- Department of Molecular Biology & the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
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203
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APOBEC3H Subcellular Localization Determinants Define Zipcode for Targeting HIV-1 for Restriction. Mol Cell Biol 2018; 38:MCB.00356-18. [PMID: 30224517 DOI: 10.1128/mcb.00356-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Accepted: 09/11/2018] [Indexed: 12/22/2022] Open
Abstract
APOBEC enzymes are DNA cytosine deaminases that normally serve as virus restriction factors, but several members, including APOBEC3H, also contribute to cancer mutagenesis. Despite their importance in multiple fields, little is known about cellular processes that regulate these DNA mutating enzymes. We show that APOBEC3H exists in two distinct subcellular compartments, cytoplasm and nucleolus, and that the structural determinants for each mechanism are genetically separable. First, native and fluorescently tagged APOBEC3Hs localize to these two compartments in multiple cell types. Second, a series of genetic, pharmacologic, and cell biological studies demonstrate active cytoplasmic and nucleolar retention mechanisms, whereas nuclear import and export occur through passive diffusion. Third, APOBEC3H cytoplasmic retention determinants relocalize APOBEC3A from a passive cell-wide state to the cytosol and, additionally, endow potent HIV-1 restriction activity. These results indicate that APOBEC3H has a structural zipcode for subcellular localization and selecting viral substrates for restriction.
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204
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Meng Q, Gao J, Zhu H, He H, Lu Z, Hong M, Zhou H. The proteomic study of serially passaged human skin fibroblast cells uncovers down-regulation of the chromosome condensin complex proteins involved in replicative senescence. Biochem Biophys Res Commun 2018; 505:1112-1120. [PMID: 30336977 DOI: 10.1016/j.bbrc.2018.10.065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 10/10/2018] [Indexed: 01/09/2023]
Abstract
Dermal fibroblast is one of the major constitutive cells of skin and plays a central role in skin senescence. The replicative senescence of fibroblasts may cause skin aging, bad wound healing, skin diseases and even cancer. In this study, a label-free quantitative proteomic approach was employed to analyzing the serial passaged human skin fibroblast (CCD-1079Sk) cells, resulting in 3371 proteins identified. Of which, 280 proteins were significantly changed in early passage (6 passages, P6), middle passage (12 passages, P12) and late passage (21 passages, P21), with a time-dependent decrease or increase tendency. Bioinformatic analysis demonstrated that the chromosome condensin complex, including structural maintenance of chromosomes protein 2 (SMC2) and structural maintenance of chromosomes protein 4 (SMC4), were down-regulated in the serially passaged fibroblast cells. The qRT-PCR and Western Blot experiments confirmed that the expression of these two proteins were significantly down-regulated in a time-dependent manner in the subculture of human skin fibroblasts (HSFb cells). In summary, we used serially passaged human skin fibroblast cells coupled with quantitative proteomic approach to profile the protein expression pattern in the temporal progress of replicative senescence in HSFb cells and revealed that the down-regulation of the chromosome condensin complex subunits, such as SMC2 and SMC4, may play an important role in the fibroblast senescence.
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Affiliation(s)
- Qian Meng
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China; University of Chinese Academy of Sciences, Number 19A Yuquan Road, Beijing, 100049, China
| | - Jing Gao
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Hongwen Zhu
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Han He
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Zhi Lu
- Technology Center, Shanghai Inoherb Co. Ltd, 121 Chengyin Road, Shanghai, 200083, China.
| | - Minhua Hong
- Technology Center, Shanghai Inoherb Co. Ltd, 121 Chengyin Road, Shanghai, 200083, China.
| | - Hu Zhou
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China; University of Chinese Academy of Sciences, Number 19A Yuquan Road, Beijing, 100049, China.
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205
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Freundt EC, Drappier M, Michiels T. Innate Immune Detection of Cardioviruses and Viral Disruption of Interferon Signaling. Front Microbiol 2018; 9:2448. [PMID: 30369921 PMCID: PMC6194174 DOI: 10.3389/fmicb.2018.02448] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/25/2018] [Indexed: 12/24/2022] Open
Abstract
Cardioviruses are members of the Picornaviridae family and infect a variety of mammals, from mice to humans. Replication of cardioviruses produces double stranded RNA that is detected by helicases in the RIG-I-like receptor family and leads to a signaling cascade to produce type I interferon. Like other viruses within Picornaviridae, however, cardioviruses have evolved several mechanisms to inhibit interferon production. In this review, we summarize recent findings that have uncovered several proteins enabling efficient detection of cardiovirus dsRNA and discuss which cell types may be most important for interferon production in vivo. Additionally, we describe how cardiovirus proteins L, 3C and L∗ disrupt interferon production and antagonize the antiviral activity of interferon effector molecules.
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Affiliation(s)
- Eric C Freundt
- Department of Biology, The University of Tampa, Tampa, FL, United States
| | - Melissa Drappier
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Thomas Michiels
- de Duve Institute, Université catholique de Louvain, Brussels, Belgium
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206
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Dakir EH, Pickard A, Srivastava K, McCrudden CM, Gross SR, Lloyd S, Zhang SD, Margariti A, Morgan R, Rudland PS, El-Tanani M. The anti-psychotic drug pimozide is a novel chemotherapeutic for breast cancer. Oncotarget 2018; 9:34889-34910. [PMID: 30405882 PMCID: PMC6201850 DOI: 10.18632/oncotarget.26175] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 09/04/2018] [Indexed: 12/14/2022] Open
Abstract
Pimozide, an antipsychotic drug of the diphenylbutylpiperidine class, has been shown to suppress cell growth of breast cancer cells in vitro. In this study we further explore the inhibitory effects of this molecule in cancer cells. We found that Pimozide inhibited cell proliferation in a dose- and time-dependent manner in MDA-MB-231 breast cancer cells and A549 lung cancer cells. Furthermore, we found that Pimozide also promoted apoptosis as demonstrated by cell cycle arrest and induction of double-strand DNA breaks but did not result in any effect in the non-transformed MCF10A breast cell line. In order to shed new lights into the molecular pathways affected by Pimozide, we show that Pimozide downregulated RAN GTPase and AKT at both protein and mRNA levels and inhibited the AKT signaling pathway in MDA-MB-231 breast cancer cells. Pimozide also inhibited the epithelial mesenchymal transition and cell migration and downregulated the expression of MMPs. Administration of Pimozide showed a potent in vivo antitumor activity in MDA-MB-231 xenograft animal model and reduced the number of lung metastases by blocking vascular endothelial growth factor receptor 2. Furthermore, Pimozide inhibited myofibroblast formation as evaluated by the reduction in α-smooth muscle actin containing cells. Thus, Pimozide might inhibit tumor development by suppressing angiogenesis and by paracrine stimulation provided by host reactive stromal cells. These results demonstrate a novel in vitro and in vivo antitumor activity of Pimozide against breast and lung cancer cells and provide the proof of concept for a putative Pimozide as a novel approach for cancer therapy.
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Affiliation(s)
- El-Habib Dakir
- Center for Cancer Research and Cell Biology, Queen's University, Belfast, UK.,Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Salamanca, Spain.,Institute of Cancer Therapeutics, University of Bradford, Bradford, UK
| | - Adam Pickard
- Center for Cancer Research and Cell Biology, Queen's University, Belfast, UK
| | - Kirtiman Srivastava
- Center for Cancer Research and Cell Biology, Queen's University, Belfast, UK
| | | | - Stephane R Gross
- School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Stephen Lloyd
- School of Medicine, Animal Facility, Queen's University Belfast, Belfast, UK
| | - Shu-Dong Zhang
- Northern Ireland Centre for Stratified Medicine, Biomedical Sciences, University of Ulster, UK
| | - Andriana Margariti
- Center of Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - Richard Morgan
- Institute of Cancer Therapeutics, University of Bradford, Bradford, UK
| | - Philip S Rudland
- Institute of integrative Biology, University of Liverpool, Liverpool, UK
| | - Mohamed El-Tanani
- Institute of Cancer Therapeutics, University of Bradford, Bradford, UK
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207
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Li Q, Zhou T, Wu F, Li N, Wang R, Zhao Q, Ma YM, Zhang JQ, Ma BL. Subcellular drug distribution: mechanisms and roles in drug efficacy, toxicity, resistance, and targeted delivery. Drug Metab Rev 2018; 50:430-447. [PMID: 30270675 DOI: 10.1080/03602532.2018.1512614] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
After administration, drug molecules usually enter target cells to access their intracellular targets. In eukaryotic cells, these targets are often located in organelles, including the nucleus, endoplasmic reticulum, mitochondria, lysosomes, Golgi apparatus, and peroxisomes. Each organelle type possesses unique biological features. For example, mitochondria possess a negative transmembrane potential, while lysosomes have an intraluminal delta pH. Other properties are common to several organelle types, such as the presence of ATP-binding cassette (ABC) or solute carrier-type (SLC) transporters that sequester or pump out xenobiotic drugs. Studies on subcellular drug distribution are critical to understand the efficacy and toxicity of drugs along with the body's resistance to them and to potentially offer hints for targeted subcellular drug delivery. This review summarizes the results of studies from 1990 to 2017 that examined the subcellular distribution of small molecular drugs. We hope this review will aid in the understanding of drug distribution within cells.
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Affiliation(s)
- Qiao Li
- a Department of Pharmacology , Shanghai University of Traditional Chinese Medicine , Shanghai , China
| | - Ting Zhou
- a Department of Pharmacology , Shanghai University of Traditional Chinese Medicine , Shanghai , China
| | - Fei Wu
- b Engineering Research Center of Modern Preparation Technology of TCM of Ministry of Education , Shanghai University of Traditional Chinese Medicine , Shanghai , China
| | - Na Li
- c Department of Chinese materia medica , School of Pharmacy , Shanghai , China
| | - Rui Wang
- b Engineering Research Center of Modern Preparation Technology of TCM of Ministry of Education , Shanghai University of Traditional Chinese Medicine , Shanghai , China
| | - Qing Zhao
- a Department of Pharmacology , Shanghai University of Traditional Chinese Medicine , Shanghai , China
| | - Yue-Ming Ma
- a Department of Pharmacology , Shanghai University of Traditional Chinese Medicine , Shanghai , China
| | - Ji-Quan Zhang
- b Engineering Research Center of Modern Preparation Technology of TCM of Ministry of Education , Shanghai University of Traditional Chinese Medicine , Shanghai , China
| | - Bing-Liang Ma
- a Department of Pharmacology , Shanghai University of Traditional Chinese Medicine , Shanghai , China
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208
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Yang YJ, Mai DJ, Dursch TJ, Olsen BD. Nucleopore-Inspired Polymer Hydrogels for Selective Biomolecular Transport. Biomacromolecules 2018; 19:3905-3916. [DOI: 10.1021/acs.biomac.8b00556] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Yun Jung Yang
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Danielle J. Mai
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Thomas J. Dursch
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Bradley D. Olsen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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209
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Friis I, Solov’yov IA. Activation of the DNA-repair mechanism through NBS1 and MRE11 diffusion. PLoS Comput Biol 2018; 14:e1006362. [PMID: 30052627 PMCID: PMC6082579 DOI: 10.1371/journal.pcbi.1006362] [Citation(s) in RCA: 4] [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: 04/11/2018] [Revised: 08/08/2018] [Accepted: 07/12/2018] [Indexed: 12/27/2022] Open
Abstract
The non-homologous end joining of a DNA double strand break is initiated by the MRE11-NBS1-RAD50 complex whose subunits are the first three proteins to arrive to the breakage site thereby making the recruitment time of MRE11, NBS1 and RAD50 essential for cell survival. In the present investigation, the nature of MRE11 and NBS1 transportation from the cytoplasm to the nucleus, hosting the damaged DNA strand, is hypothesized to be a passive diffusive process. The feasibility of such a mechanism is addressed through theoretical and computational approaches which permit establishing the characteristic recruitment time of MRE11 and NBS1 by the nucleus. A computational model of a cell is constructed from a set of biological parameters and the kinetic Monte Carlo algorithm is used to simulate the diffusing MRE11 and NBS1 particles as a random walk process. To accurately describe the experimented data, it is discovered that MRE11 and NBS1 should start diffusion from significantly different starting positions which suggests that diffusion might not be the only transport mechanism of repair protein recruitment to the DNA break. The DNA repair mechanism is crucial for a cell to avoid apoptosis, and is a complicated process involving many different repair proteins. The mean of transportation of these repair proteins is largely unknown as their transportation mechanisms need clarification. We have focused on the transportation of some of the first proteins to arrive to the damaged DNA from the cytoplasm, namely the MRE11 and NBS1. Our hypothesis of diffusion as the transportation mechanism of MRE11 and NBS1 is tested against a theoretical model as well as simulation data and experiments, revealing a possibility for diffusion to be the method of recruiting MRE11 and NBS1 to the DNA break.
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Affiliation(s)
- Ida Friis
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
- * E-mail: (IF); (IAS)
| | - Ilia A. Solov’yov
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
- On leave from the Ioffe Institute, Politechnicheskaya Str. 26, 94021, St. Petersburg, Russia
- * E-mail: (IF); (IAS)
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210
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Soto M, García-Santisteban I, Krenning L, Medema RH, Raaijmakers JA. Chromosomes trapped in micronuclei are liable to segregation errors. J Cell Sci 2018; 131:jcs.214742. [PMID: 29930083 PMCID: PMC6051344 DOI: 10.1242/jcs.214742] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 05/30/2018] [Indexed: 12/29/2022] Open
Abstract
DNA in micronuclei is likely to get damaged. When shattered DNA from micronuclei gets reincorporated into the primary nucleus, aberrant rearrangements can take place, a phenomenon referred to as chromothripsis. Here, we investigated how chromatids from micronuclei act in subsequent divisions and how this affects their fate. We observed that the majority of chromatids derived from micronuclei fail to establish a proper kinetochore in mitosis, which is associated with problems in chromosome alignment, segregation and spindle assembly checkpoint activation. Remarkably, we found that, upon their formation, micronuclei already display decreased levels of important kinetochore assembly factors. Importantly, these defects favour the exclusion of the micronucleus over the reintegration into the primary nucleus over several divisions. Interestingly, the defects observed in micronuclei are likely overcome once micronuclei are reincorporated into the primary nuclei, as they further propagate normally. We conclude that the formation of a separate small nuclear entity represents a mechanism for the cell to delay the stable propagation of excess chromosome(s) and/or damaged DNA, by inducing kinetochore defects. Highlighted Article: Micronuclei, which are common in cancer cells, are prone to missegregation owing to kinetochore assembly defects. This represents a mechanism to delay the reincorporation of excess chromosome(s) and/or damaged DNA.
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Affiliation(s)
- Mar Soto
- Oncode Institute, Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Iraia García-Santisteban
- Oncode Institute, Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Lenno Krenning
- Oncode Institute, Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - René H Medema
- Oncode Institute, Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Jonne A Raaijmakers
- Oncode Institute, Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
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211
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Aksu M, Pleiner T, Karaca S, Kappert C, Dehne HJ, Seibel K, Urlaub H, Bohnsack MT, Görlich D. Xpo7 is a broad-spectrum exportin and a nuclear import receptor. J Cell Biol 2018; 217:2329-2340. [PMID: 29748336 PMCID: PMC6028547 DOI: 10.1083/jcb.201712013] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 04/09/2018] [Accepted: 04/24/2018] [Indexed: 11/28/2022] Open
Abstract
Exportins bind cargo molecules in a RanGTP-dependent manner inside nuclei and transport them through nuclear pores to the cytoplasm. CRM1/Xpo1 is the best-characterized exportin because specific inhibitors such as leptomycin B allow straightforward cargo validations in vivo. The analysis of other exportins lagged far behind, foremost because no such inhibitors had been available for them. In this study, we explored the cargo spectrum of exportin 7/Xpo7 in depth and identified not only ∼200 potential export cargoes but also, surprisingly, ∼30 nuclear import substrates. Moreover, we developed anti-Xpo7 nanobodies that acutely block Xpo7 function when transfected into cultured cells. The inhibition is pathway specific, mislocalizes export cargoes of Xpo7 to the nucleus and import substrates to the cytoplasm, and allowed validation of numerous tested cargo candidates. This establishes Xpo7 as a broad-spectrum bidirectional transporter and paves the way for a much deeper analysis of exportin and importin function in the future.
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Affiliation(s)
- Metin Aksu
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Tino Pleiner
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Samir Karaca
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christin Kappert
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Heinz-Jürgen Dehne
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Katharina Seibel
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Institute for Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Markus T Bohnsack
- Institute for Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Dirk Görlich
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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212
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Linker of nucleoskeleton and cytoskeleton complex proteins in cardiomyopathy. Biophys Rev 2018; 10:1033-1051. [PMID: 29869195 PMCID: PMC6082319 DOI: 10.1007/s12551-018-0431-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 05/24/2018] [Indexed: 12/21/2022] Open
Abstract
The linker of nucleoskeleton and cytoskeleton (LINC) complex couples the nuclear lamina to the cytoskeleton. The LINC complex and its associated proteins play diverse roles in cells, ranging from genome organization, nuclear morphology, gene expression, to mechanical stability. The importance of a functional LINC complex is highlighted by the large number of mutations in genes encoding LINC complex proteins that lead to skeletal and cardiac myopathies. In this review, the structure, function, and interactions between components of the LINC complex will be described. Mutations that are known to cause cardiomyopathy in patients will be discussed alongside their respective mouse models. Furthermore, future challenges for the field and emerging technologies to investigate LINC complex function will be discussed.
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213
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Nuclear accumulation of SHIP1 mutants derived from AML patients leads to increased proliferation of leukemic cells. Cell Signal 2018; 49:87-94. [PMID: 29852247 DOI: 10.1016/j.cellsig.2018.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 05/18/2018] [Accepted: 05/18/2018] [Indexed: 11/22/2022]
Abstract
The inositol 5-phosphatase SHIP1 acts as negative regulator of intracellular signaling in myeloid cells and is a tumor suppressor in myeloid leukemogenesis. After relocalization from the cytoplasm to the plasma membrane SHIP1 terminates PI3-kinase mediated signaling processes. Furthermore, SHIP1 is also found in distinct puncta in the cell nucleus and nuclear SHIP1 has a pro-proliferative function. Here we report the identification of five nuclear export signals (NESs) which regulate together with the two known nuclear localization signals (NLSs) the nucleocytoplasmic shuttling of SHIP1. Mutation of NLSs reduced the nuclear import and mutation of NESs decreased the nuclear export of SHIP1 in the acute myeloid leukemia (AML) cell line UKE-1. Interestingly, four SHIP1 mutants (K210R, N508D, V684E, Q1153L) derived from AML patients showed a nuclear accumulation after expression in UKE-1 cells. In addition, overexpression of the AML patient-derived mutation N508D caused an increased proliferation rate of UKE-1 cells in comparison to wild type SHIP1. Furthermore, we identified serine and tyrosine phosphorylation as a molecular mechanism for the regulation of nucleocytoplasmic shuttling of SHIP1 where tyrosine phosphorylation of distinct residues i.e. Y864, Y914, Y1021 reduces nuclear localization, whereas serine phosphorylation at S933 enhances nuclear localization of SHIP1. In summary, our data further implicate nuclear SHIP1 in cellular signaling and suggest that enhanced accumulation of SHIP1 mutants in the nucleus may be a contributory factor of abnormally high proliferation of AML cells.
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Bao XX, Spanos C, Kojidani T, Lynch EM, Rappsilber J, Hiraoka Y, Haraguchi T, Sawin KE. Exportin Crm1 is repurposed as a docking protein to generate microtubule organizing centers at the nuclear pore. eLife 2018; 7:e33465. [PMID: 29809148 PMCID: PMC6008054 DOI: 10.7554/elife.33465] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 05/21/2018] [Indexed: 01/04/2023] Open
Abstract
Non-centrosomal microtubule organizing centers (MTOCs) are important for microtubule organization in many cell types. In fission yeast Schizosaccharomyces pombe, the protein Mto1, together with partner protein Mto2 (Mto1/2 complex), recruits the γ-tubulin complex to multiple non-centrosomal MTOCs, including the nuclear envelope (NE). Here, we develop a comparative-interactome mass spectrometry approach to determine how Mto1 localizes to the NE. Surprisingly, we find that Mto1, a constitutively cytoplasmic protein, docks at nuclear pore complexes (NPCs), via interaction with exportin Crm1 and cytoplasmic FG-nucleoporin Nup146. Although Mto1 is not a nuclear export cargo, it binds Crm1 via a nuclear export signal-like sequence, and docking requires both Ran in the GTP-bound state and Nup146 FG repeats. In addition to determining the mechanism of MTOC formation at the NE, our results reveal a novel role for Crm1 and the nuclear export machinery in the stable docking of a cytoplasmic protein complex at NPCs.
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Affiliation(s)
- Xun X Bao
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Christos Spanos
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Tomoko Kojidani
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Department of Chemical and Biological Sciences, Faculty of ScienceJapan Women’s UniversityTokyoJapan
| | - Eric M Lynch
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
- Department of BioanalyticsInstitute of Biotechnology, Technische Universität BerlinBerlinGermany
| | - Yasushi Hiraoka
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
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Puertollano R, Ferguson SM, Brugarolas J, Ballabio A. The complex relationship between TFEB transcription factor phosphorylation and subcellular localization. EMBO J 2018; 37:embj.201798804. [PMID: 29764979 DOI: 10.15252/embj.201798804] [Citation(s) in RCA: 317] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 02/01/2018] [Accepted: 03/07/2018] [Indexed: 12/16/2022] Open
Abstract
The MiT-TFE family of basic helix-loop-helix leucine-zipper transcription factors includes four members: TFEB, TFE3, TFEC, and MITF Originally described as oncogenes, these factors play a major role as regulators of lysosome biogenesis, cellular energy homeostasis, and autophagy. An important mechanism by which these transcription factors are regulated involves their shuttling between the surface of lysosomes, the cytoplasm, and the nucleus. Such dynamic changes in subcellular localization occur in response to nutrient fluctuations and various forms of cell stress and are mediated by changes in the phosphorylation of multiple conserved amino acids. Major kinases responsible for MiT-TFE protein phosphorylation include mTOR, ERK, GSK3, and AKT In addition, calcineurin de-phosphorylates MiT-TFE proteins in response to lysosomal calcium release. Thus, through changes in the phosphorylation state of MiT-TFE proteins, lysosome function is coordinated with the cellular metabolic state and cellular demands. This review summarizes the evidence supporting MiT-TFE regulation by phosphorylation at multiple key sites. Elucidation of such regulatory mechanisms is of fundamental importance to understand how these transcription factors contribute to both health and disease.
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Affiliation(s)
- Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shawn M Ferguson
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT, USA .,Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - James Brugarolas
- Kidney Cancer Program, Simmons Comprehensive Cancer Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA .,Hematology-Oncology Division, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Andrea Ballabio
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli (Naples), Italy .,Department of Translational Medical Sciences, Federico II University, Naples, Italy.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
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216
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Ogawa Y, Imamoto N. Nuclear transport adapts to varying heat stress in a multistep mechanism. J Cell Biol 2018; 217:2341-2352. [PMID: 29748335 PMCID: PMC6028528 DOI: 10.1083/jcb.201712042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 04/06/2018] [Accepted: 04/20/2018] [Indexed: 12/18/2022] Open
Abstract
Appropriate cell growth conditions are limited to a narrow temperature range. Once the temperature is out of this range, cells respond to protect themselves, but temperature thresholds at which various intracellular responses occur, including nuclear transport systems, remain unclear. Using a newly developed precise temperature shift assay, we found that individual transport pathways have different sensitivities to a rise in temperature. Nuclear translocations of molecular chaperone HSP70s occur at a much lower temperature than the inhibition of Ran-dependent transport. Subsequently, importin (Imp) α/β-dependent import ceases at a lower temperature than other Ran-dependent transport, suggesting that these are controlled by independent mechanisms. In vitro research revealed that the inhibition of Imp α/β-dependent import is caused by the dysfunction of Imp α1 specifically at lower temperature. Thus, the thermosensitivity of Imp α1 modulates transport balances and enables the multistep shutdown of Ran-dependent transport systems according to the degree of heat stress.
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Affiliation(s)
- Yutaka Ogawa
- Cellular Dynamics Laboratory, RIKEN Cluster for Pioneering Research, Saitama, Japan
| | - Naoko Imamoto
- Cellular Dynamics Laboratory, RIKEN Cluster for Pioneering Research, Saitama, Japan
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217
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Id1 and Sonic Hedgehog Mediate Cell Cycle Reentry and Apoptosis Induced by Amyloid Beta-Peptide in Post-mitotic Cortical Neurons. Mol Neurobiol 2018; 56:465-489. [PMID: 29721855 DOI: 10.1007/s12035-018-1098-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/24/2018] [Indexed: 10/17/2022]
Abstract
Amyloid beta-peptide (Aβ), the neurotoxic component of senile plaques in Alzheimer's disease (AD) brains, is known to trigger cell cycle reentry in post-mitotic neurons followed by apoptosis. However, the underlying mechanisms remain unclear. Recently, we have reported that Aβs stimulate the expression of inhibitor of differentiation-1 (Id1) to induce sonic hedgehog (SHH) (Hung et al., Mol Neurobiol 53(2):793-809, 2016), and both are mitogens capable of triggering cell cycle progression. In this work, we tested the hypothesis that Aβ-induced Id1 and SHH contribute to cell cycle reentry leading to apoptosis in neurons. We found that Aβ triggered cell cycle progression in the post-mitotic neurons, as indicated by the increased expression of two G1-phase markers including cyclin D1 and phosphorylated retinoblastoma protein (pRb), two G2-phase markers such as proliferating cell nuclear antigen (PCNA) and incorporation of 5-bromo-2'-deoxyuridine (BrdU) into newly synthesized DNA, as well as the mitotic marker histone H3 phosphorylated at Ser-10. As expected, Aβ also enhanced caspase-3 cleavage in the cortical neurons. Id1 siRNA, the neutralization antibody against SHH (SHH-Ab), and the cyclin-dependent kinase (CDK)-4/6 inhibitor PD0332991 all attenuated, in part or in full, the Aβ-induced expression of these cell cycle markers. Indeed, exogenous recombinant Id1 protein and the biologically active N-terminal fragment of SHH (SHH-N) were both sufficient to enhance the expression of cell cycle markers independent of Aβ. Taken together, our results revealed the critical roles of Id1 and SHH mediating Aβ-dependent cell cycle reentry and subsequently caspase-dependent apoptosis in the fully differentiated post-mitotic neurons, at least in vitro.
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Li Z, Zhang Y, Jiang Z, Jin X, Zhang K, Wang X, Han C, Yu J, Li D. Hijacking of the nucleolar protein fibrillarin by TGB1 is required for cell-to-cell movement of Barley stripe mosaic virus. MOLECULAR PLANT PATHOLOGY 2018; 19:1222-1237. [PMID: 28872759 PMCID: PMC6638131 DOI: 10.1111/mpp.12612] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/31/2017] [Accepted: 09/04/2017] [Indexed: 05/18/2023]
Abstract
Barley stripe mosaic virus (BSMV) Triple Gene Block1 (TGB1) is a multifunctional movement protein with RNA-binding, ATPase and helicase activities which mainly localizes to the plasmodesmata (PD) in infected cells. Here, we show that TGB1 localizes to the nucleus and the nucleolus, as well as the cytoplasm, and that TGB1 nuclear-cytoplasmic trafficking is required for BSMV cell-to-cell movement. Prediction analyses and laser scanning confocal microscopy (LSCM) experiments verified that TGB1 possesses a nucleolar localization signal (NoLS) (amino acids 95-104) and a nuclear localization signal (NLS) (amino acids 227-238). NoLS mutations reduced BSMV cell-to-cell movement significantly, whereas NLS mutations almost completely abolished movement. Furthermore, neither the NoLS nor NLS mutant viruses could infect Nicotiana benthamiana systemically, although the NoLS mutant virus was able to establish systemic infections of barley. Protein interaction experiments demonstrated that TGB1 interacts directly with the glycine-arginine-rich (GAR) domain of the nucleolar protein fibrillarin (Fib2). Moreover, in BSMV-infected cells, Fib2 accumulation increased by about 60%-70% and co-localized with TGB1 in the plasmodesmata. In addition, BSMV cell-to-cell movement in fib2 knockdown transgenic plants was reduced to less than one-third of that of non-transgenic plants. Fib2 also co-localized with both TGB1 and BSMV RNA, which are the main components of the ribonucleoprotein (RNP) movement complex. Collectively, these results show that TGB1-Fib2 interactions play a direct role in cell-to-cell movement, and we propose that Fib2 is hijacked by BSMV TGB1 to form a BSMV RNP which functions in cell-to-cell movement.
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Affiliation(s)
- Zhenggang Li
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
| | - Yongliang Zhang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
| | - Zhihao Jiang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
| | - Xuejiao Jin
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
| | - Kun Zhang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
| | - Xianbing Wang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
| | - Chenggui Han
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
| | - Jialin Yu
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
| | - Dawei Li
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological SciencesChina Agricultural UniversityBeijing 100193China
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Wang J, Zhuo Z, Chen M, Zhu J, Zhao J, Zhang J, Chen S, He J, Zhou H. RAN/RANBP2 polymorphisms and neuroblastoma risk in Chinese children: a three-center case-control study. Aging (Albany NY) 2018; 10:808-818. [PMID: 29706609 PMCID: PMC5940104 DOI: 10.18632/aging.101429] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 04/20/2018] [Indexed: 02/06/2023]
Abstract
The genetic etiology of sporadic neuroblastoma remains largely obscure. RAN and RANBP2 genes encode Ras-related nuclear protein and Ran-binding protein 2, respectively. These two proteins form Ran-RanBP2 complex that regulate various cellular activities including nuclear transport. Aberrant functions of the two proteins are implicated in carcinogenesis. Given the unknown role of RAN/RANBP2 single nucleotide polymorphisms (SNPs) in neuroblastoma risk, we performed a multi-center case-control study in Chinese children to assess the association of the RAN/RANBP2 SNPs with neuroblastoma risk. We analyzed three potentially functional SNPs in RAN gene (rs56109543 C>T, rs7132224 A>G, rs14035 C>T) and one in RANBP2 (rs2462788 C>T) in 429 cases and 884 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to access the association between these four polymorphisms and neuroblastoma risk. No single variant was found to statistically significantly associate with neuroblastoma risk. However, individuals with 3 protective genotypes were less likely to develop neuroblastoma, in comparison to non-carriers (adjusted OR=0.33; 95% CI=0.12-0.96; P=0.042), as well as those with 0-2 protective genotypes (adjusted OR=0.33; 95% CI=0.11-0.94; P=0.038). Stratified analysis revealed no significant association for any of the four polymorphisms. Further studies are warranted to validate the weak impact of RAN/RANBP2 SNPs on neuroblastoma risk.
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Affiliation(s)
- Juxiang Wang
- Department of Hematology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, Zhejiang, China
- Equal contribution
| | - Zhenjian Zhuo
- School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong 999077, China
- Equal contribution
| | - Min Chen
- Department of Hematology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, Zhejiang, China
| | - Jinhong Zhu
- Department of Clinical Laboratory, Molecular Epidemiology Laboratory, Harbin Medical University Cancer Hospital, Harbin 150040, Heilongjiang, China
| | - Jie Zhao
- Department of Hematology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, Zhejiang, China
| | - Jiao Zhang
- Department of Pediatric Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, Henan, China
| | - Shanshan Chen
- Department of Hematology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, Zhejiang, China
| | - Jing He
- Department of Hematology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, Zhejiang, China
- Department of Pediatric Surgery, Guangzhou Institute of Pediatrics, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Haixia Zhou
- Department of Hematology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, Zhejiang, China
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221
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Onuma A, Fujioka YA, Fujii W, Sugiura K, Naito K. Effects of exportin 1 on nuclear transport and meiotic resumption in porcine full-grown and growing oocytes. Biol Reprod 2018; 98:501-509. [PMID: 29228114 DOI: 10.1093/biolre/iox168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 12/07/2017] [Indexed: 12/17/2023] Open
Abstract
Exportin 1 (XPO1) is a nuclear transport receptor involved in the nuclear export of majority proteins in somatic cells. In mammalian oocytes, however, only the presence of XPO1 has been reported at mRNA and protein levels, and the definitive functions of XPO1 and its effects on the meiotic maturation of oocytes have never been directly examined. In the present study, the expression state and the nuclear-export function of porcine XPO1 were analyzed in porcine oocytes. In addition, we investigated the effects of the overexpression and inhibition of XPO1 on meiotic regulation in full-grown and growing oocytes by mRNA injection and inhibitor treatment. Endogenous XPO1 was stably expressed in porcine oocytes during the germinal vesicle (GV) stage, and the expression of exogenous XPO1 significantly decreased the nuclear localization of XPO1 cargos, snurportin 1, and WEE1B. Inhibition of XPO1 by a specific inhibitor, leptomycin B, delayed the GV breakdown (GVBD), whereas the overexpression of XPO1 by mRNA injection accelerated the GVBD. XPO1 overexpression overcame the meiotic arrest induced by WEE1B expression in full-grown oocytes. Surprisingly, the GVBD of porcine growing oocytes, which could not resume meiosis by the maturation culture in vitro, was induced by the expression of exogenous XPO1. These results showed the presence of XPO1 and its function as a nuclear export receptor in mammalian oocytes, including growing oocytes, and they suggest that the regulation of nuclear transport has a large influence on the GV maintenance and meiotic resumption of oocytes.
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Affiliation(s)
- Asuka Onuma
- Department of Animal Resource Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yoshie A Fujioka
- Department of Animal Resource Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Wataru Fujii
- Department of Animal Resource Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Koji Sugiura
- Department of Animal Resource Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Kunihiko Naito
- Department of Animal Resource Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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Deniset JF, Hedley TE, Hlaváčková M, Chahine MN, Dibrov E, O'Hara K, Maddaford GG, Nelson D, Maddaford TG, Fandrich R, Kardami E, Pierce GN. Heat shock protein 60 involvement in vascular smooth muscle cell proliferation. Cell Signal 2018; 47:44-51. [PMID: 29596871 DOI: 10.1016/j.cellsig.2018.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/23/2018] [Accepted: 03/23/2018] [Indexed: 10/17/2022]
Abstract
AIM Heat shock protein 60 (Hsp60) is a mediator of stress-induced vascular smooth muscle cell (VSMC) proliferation. This study will determine, first, if the mitochondrial or cytoplasmic localization of Hsp60 is critical to VSMC proliferation and, second, the mechanism of Hsp60 induction of VSMC proliferation with a focus on modification of nucleocytoplasmic trafficking. METHODS AND RESULTS Hsp60 was overexpressed in primary rabbit VSMCs with or without a mitochondrial targeting sequence (AdHsp60mito-). Both interventions induced an increase in VSMC PCNA expression and proliferation. The increase in VSMC PCNA expression and growth was not observed after siRNA-mediated knockdown of Hsp60 expression. Nuclear protein import in VSMC was measured by fluorescent microscopy using a microinjected fluorescent import substrate. Nuclear protein import was stimulated by both AdHsp60 and AdHsp60mito- treatments. AdHsp60 treatment also induced increases in nucleoporin (Nup) 62, Nup153, importin-α, importin-β and Ran expression as well as cellular ATP levels compared to control. AdHsp60mito- treatment induced an up-regulation in importin-α, importin-β and Ran expression compared to control. Hsp60 knockdown did not change nuclear protein import nor the expression of any nuclear transport receptors or nucleoporins. Both heat shock treatment and Hsp60 overexpression promoted the interaction of Ran with Hsp60. CONCLUSIONS VSMC proliferation can be modulated via an Hsp60 dependent, cytosol localized mechanism that in part involves a stimulation of nuclear protein import through an interaction with Ran. This novel cellular signaling role for Hsp60 may be important in growth-based vascular pathologies like atherosclerosis and hypertension.
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Affiliation(s)
- Justin F Deniset
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada
| | - Thomas E Hedley
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada
| | - Markéta Hlaváčková
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Mirna N Chahine
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada
| | - Elena Dibrov
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada
| | - Kim O'Hara
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada
| | - Graham G Maddaford
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada
| | - David Nelson
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada
| | - Thane G Maddaford
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada
| | - Robert Fandrich
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Anatomy and Cell Biology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Elissavet Kardami
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Anatomy and Cell Biology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Grant N Pierce
- Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St Boniface Hospital, Canada; Departments of Physiology and Pathophysiology, Canada.
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Cancer Stem Cell-Related Marker NANOG Expression in Ovarian Serous Tumors: A Clinicopathological Study of 159 Cases. Int J Gynecol Cancer 2018; 27:2006-2013. [PMID: 28906309 DOI: 10.1097/igc.0000000000001105] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE The objectives of this study were to assess cancer stem cell-related marker NANOG expression in ovarian serous tumors and to evaluate its prognostic significance in relation to ovarian serous carcinoma. METHODS NANOG protein expression was immunohistochemically evaluated in the ovarian tissue microarrays of 20 patients with benign ovarian serous tumors, 30 patients with borderline ovarian serous tumors, and 109 patients with ovarian serous carcinomas, from which 106 were of high-grade and 3 of low-grade morphology Immunohistochemical reaction was scored according to signal intensity and the percentage of positive cells in tumor samples. Pursuant to our summation of signal intensity and positive cell occurrence, we divided our samples into 4 groups: NANOG-negative, NANOG-slightly positive, NANOG-moderately positive, and NANOG-strongly positive group. Complete clinical data were obtained for the ovarian serous carcinoma group, and correlation between clinical data and NANOG expression was analyzed. RESULTS A specific brown nuclear, or cytoplasmic reaction, was considered a positive NANOG staining. In terms of the ovarian serous carcinoma group, 69.7% were NANOG positive, 22.9% slightly positive, 22.9% moderately positive, and 23.9% strongly positive. All NANOG-positive cases were of high-grade morphology. Benign and borderline tumors and low-grade serous carcinomas were NANOG negative. There was no significant correlation between NANOG expression and clinical parameters in terms of the ovarian serous carcinoma group. CONCLUSIONS Positive NANOG expression is significantly associated with high-grade ovarian serous carcinoma and is absent in benign, borderline, and low-grade serous lesions. In our study, there was no correlation between NANOG expression and clinical parameters, including its use in the prognosis of ovarian serous carcinoma.
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RanGTPase regulates the interaction between the inner nuclear membrane proteins, Samp1 and Emerin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1326-1334. [PMID: 29510091 DOI: 10.1016/j.bbamem.2018.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 02/07/2018] [Accepted: 03/01/2018] [Indexed: 02/02/2023]
Abstract
Samp1, spindle associated membrane protein 1, is a type II integral membrane protein localized in the inner nuclear membrane. Recent studies have shown that the inner nuclear membrane protein, Emerin and the small monomeric GTPase, Ran are direct binding partners of Samp1. Here we addressed the question whether Ran could regulate the interaction between Samp1 and Emerin in the inner nuclear membrane. To investigate the interaction between Samp1 and Emerin in live cells, we performed FRAP experiments in cells overexpressing YFP-Emerin. We compared the mobility of YFP-Emerin in Samp1 knock out cells and cells overexpressing Samp1. The results showed that the mobility of YFP-Emerin was higher in Samp1 knock out cells and lower in cells overexpressing Samp1, suggesting that Samp1 significantly attenuates the mobility of Emerin in the nuclear envelope. FRAP experiments using tsBN2 cells showed that the mobility of Emerin depends on RanGTP. Consistently, in vitro binding experiments showed that the affinity between Samp1 and Emerin is decreased in the presence of Ran, suggesting that Ran attenuates the interaction between Samp1 and Emerin. This is the first demonstration that Ran can regulate the interaction between two proteins in the nuclear envelope.
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Yoon J, Kim SJ, An S, Cho S, Leitner A, Jung T, Aebersold R, Hebert H, Cho US, Song JJ. Integrative Structural Investigation on the Architecture of Human Importin4_Histone H3/H4_Asf1a Complex and Its Histone H3 Tail Binding. J Mol Biol 2018; 430:822-841. [DOI: 10.1016/j.jmb.2018.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 01/22/2018] [Accepted: 01/23/2018] [Indexed: 11/15/2022]
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Middleton AM, Dal Bosco C, Chlap P, Bensch R, Harz H, Ren F, Bergmann S, Wend S, Weber W, Hayashi KI, Zurbriggen MD, Uhl R, Ronneberger O, Palme K, Fleck C, Dovzhenko A. Data-Driven Modeling of Intracellular Auxin Fluxes Indicates a Dominant Role of the ER in Controlling Nuclear Auxin Uptake. Cell Rep 2018. [DOI: 10.1016/j.celrep.2018.02.074] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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227
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Imamoto N. Heat stress-induced nuclear transport mediated by Hikeshi confers nuclear function of Hsp70s. Curr Opin Cell Biol 2018; 52:82-87. [PMID: 29490261 DOI: 10.1016/j.ceb.2018.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/05/2018] [Accepted: 02/13/2018] [Indexed: 12/18/2022]
Abstract
The prime feature of eukaryotic cells is the separation of the intracellular space into two compartments, the nucleus and the cytoplasm. Active nuclear transport is crucial for the maintenance of this separation. In this report, we focus on a nuclear transport receptor named Hikeshi, which mediates the heat stress-induced nuclear import of 70-kDa heat shock proteins (Hsp70s), and discuss how the same protein can function differently depending on the cellular compartment in which it is localized. Hsp70 is a molecular chaperone that is predominantly localized in the cytoplasm under normal conditions but is known to accumulate in the nucleus under conditions of heat stress. Although the reported function of Hsp70 is mostly attributed to its molecular function in the cytoplasm, the functions of Hsp70 may extend beyond molecular chaperone activity in the nucleus.
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Affiliation(s)
- Naoko Imamoto
- Cellular Dynamics Laboratory, Riken, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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Karyopherin α-3 is a key protein in the pathogenesis of spinocerebellar ataxia type 3 controlling the nuclear localization of ataxin-3. Proc Natl Acad Sci U S A 2018; 115:E2624-E2633. [PMID: 29476013 DOI: 10.1073/pnas.1716071115] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disorder caused by a CAG expansion in the ATXN3 gene leading to a polyglutamine expansion in the ataxin-3 protein. The nuclear presence and aggregation of expanded ataxin-3 are critical steps in disease pathogenesis. To identify novel therapeutic targets, we investigated the nucleocytoplasmic transport system by screening a collection of importins and exportins that potentially modulate this nuclear localization. Using cell, Drosophila, and mouse models, we focused on three transport proteins, namely, CRM1, IPO13, KPNA3, and their respective Drosophila orthologs Emb, Cdm, and Kap-α3. While overexpression of CRM1/Emb demonstrated positive effects in Drosophila, KPNA3/Kap-α3 emerged as the most promising target, as knockdown via multiple RNAi lines demonstrated its ability to shuttle both truncated and full-length expanded ataxin-3, rescue neurodegeneration, restore photoreceptor formation, and reduce aggregation. Furthermore, KPNA3 knockout in SCA3 mice resulted in an amelioration of molecular and behavioral disturbances such as total activity, anxiety, and gait. Since KPNA3 is known to function as an import protein and recognize nuclear localization signals (NLSs), this work unites ataxin-3 structure to the nuclear pore machinery and provides a link between karyopherins, NLS signals, and polyglutamine disease, as well as demonstrates that KPNA3 is a key player in the pathogenesis of SCA3.
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229
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Zhu WJ. Transmission electron microscopy analysis of the origin and incidence of sperm intranuclear cytoplasmic retention in fertile and teratozoospermia men. Andrology 2018; 6:317-324. [PMID: 29457364 DOI: 10.1111/andr.12469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 12/31/2017] [Accepted: 01/02/2018] [Indexed: 11/27/2022]
Abstract
The human sperm nucleus contains cytoplasm. However, the origin and incidence of human sperm intranuclear cytoplasmic retention (INCR) remain unknown. The objectives of this study were to observe the morphological origin of INCR within the seminiferous epithelium and investigate the incidence of INCR in fertile and teratozoospermia men using transmission electron microscopy (TEM). By TEM, INCR initially appeared in elongating round spermatid nuclei and varied in size, number, shape, content, location and distribution within sperm nuclei. The teratozoospermia group (n = 16) demonstrated a higher incidence of INCR than did the fertile group (n = 16) (17.6 ± 5.2% vs. 9.7 ± 3.4%; p = 0.000). In the fertile group, no correlations were found between the incidence of INCR and abnormal sperm morphology, nuclear vacuole, acrosome integrity, motility or concentration (p > 0.05). However, the incidence of INCR exhibited a positive relationship with sperm abnormal morphology in the teratozoospermia group (r = 0.616, p = 0.011). These results demonstrate that INCR occurs in the early process of spermatogenesis and is an alteration found in the nucleus. Spermatozoa from teratozoospermia men contained more INCRs than those from fertile males. More attention should be paid to the possibility of spermatozoa containing INCR when using spermatozoa with abnormal head morphology for clinical or diagnostic purposes.
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Affiliation(s)
- W-J Zhu
- Department of Developmental and Regenerative Biology, College of Life Science and Technology, Jinan University, Guangzhou, China
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230
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Schrenk C, Fetz V, Vallet C, Heiselmayer C, Schröder E, Hensel A, Hahlbrock A, Wünsch D, Goesswein D, Bier C, Habtemichael N, Schneider G, Stauber RH, Knauer SK. TFIIA transcriptional activity is controlled by a 'cleave-and-run' Exportin-1/Taspase 1-switch. J Mol Cell Biol 2018; 10:33-47. [PMID: 28992066 DOI: 10.1093/jmcb/mjx025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 07/09/2017] [Indexed: 12/24/2022] Open
Abstract
Transcription factor TFIIA is controlled by complex regulatory networks including proteolysis by the protease Taspase 1, though the full impact of cleavage remains elusive. Here, we demonstrate that in contrast to the general assumption, de novo produced TFIIA is rapidly confined to the cytoplasm via an evolutionary conserved nuclear export signal (NES, amino acids 21VINDVRDIFL30), interacting with the nuclear export receptor Exportin-1/chromosomal region maintenance 1 (Crm1). Chemical export inhibition or genetic inactivation of the NES not only promotes TFIIA's nuclear localization but also affects its transcriptional activity. Notably, Taspase 1 processing promotes TFIIA's nuclear accumulation by NES masking, and modulates its transcriptional activity. Moreover, TFIIA complex formation with the TATA box binding protein (TBP) is cooperatively enhanced by inhibition of proteolysis and nuclear export, leading to an increase of the cell cycle inhibitor p16INK, which is counteracted by prevention of TBP binding. We here identified a novel mechanism how proteolysis and nuclear transport cooperatively fine-tune transcriptional programs.
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Affiliation(s)
- Christian Schrenk
- Molecular and Cellular Oncology/ENT, University Hospital of Mainz, 55101 Mainz, Germany
| | - Verena Fetz
- Molecular and Cellular Oncology/ENT, University Hospital of Mainz, 55101 Mainz, Germany
| | - Cecilia Vallet
- Molecular Biology, Centre for Medical Biotechnology (ZMB), University Duisburg-Essen, 45141 Essen, Germany
| | - Christina Heiselmayer
- Molecular Biology, Centre for Medical Biotechnology (ZMB), University Duisburg-Essen, 45141 Essen, Germany
| | - Elisabeth Schröder
- Molecular Biology, Centre for Medical Biotechnology (ZMB), University Duisburg-Essen, 45141 Essen, Germany
| | - Astrid Hensel
- Molecular Biology, Centre for Medical Biotechnology (ZMB), University Duisburg-Essen, 45141 Essen, Germany
| | - Angelina Hahlbrock
- Molecular and Cellular Oncology/ENT, University Hospital of Mainz, 55101 Mainz, Germany
| | - Désirée Wünsch
- Molecular and Cellular Oncology/ENT, University Hospital of Mainz, 55101 Mainz, Germany
| | - Dorothee Goesswein
- Molecular and Cellular Oncology/ENT, University Hospital of Mainz, 55101 Mainz, Germany
| | - Carolin Bier
- Molecular and Cellular Oncology/ENT, University Hospital of Mainz, 55101 Mainz, Germany
| | - Negusse Habtemichael
- Molecular and Cellular Oncology/ENT, University Hospital of Mainz, 55101 Mainz, Germany
| | - Günter Schneider
- University Hospital Klinikum rechts der Isar, II. Medizinische Klinik, Technical University München, 81675 Munich, Germany
| | - Roland H Stauber
- Molecular and Cellular Oncology/ENT, University Hospital of Mainz, 55101 Mainz, Germany
| | - Shirley K Knauer
- Molecular Biology, Centre for Medical Biotechnology (ZMB), University Duisburg-Essen, 45141 Essen, Germany
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231
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Pickens JA, Tripp RA. Verdinexor Targeting of CRM1 is a Promising Therapeutic Approach against RSV and Influenza Viruses. Viruses 2018; 10:E48. [PMID: 29361733 PMCID: PMC5795461 DOI: 10.3390/v10010048] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Revised: 01/15/2018] [Accepted: 01/17/2018] [Indexed: 12/11/2022] Open
Abstract
Two primary causes of respiratory tract infections are respiratory syncytial virus (RSV) and influenza viruses, both of which remain major public health concerns. There are a limited number of antiviral drugs available for the treatment of RSV and influenza, each having limited effectiveness and each driving selective pressure for the emergence of drug-resistant viruses. Novel broad-spectrum antivirals are needed to circumvent problems with current disease intervention strategies, while improving the cytokine-induced immunopathology associated with RSV and influenza infections. In this review, we examine the use of Verdinexor (KPT-335, a novel orally bioavailable drug that functions as a selective inhibitor of nuclear export, SINE), as an antiviral with multifaceted therapeutic potential. KPT-335 works to (1) block CRM1 (i.e., Chromosome Region Maintenance 1; exportin 1 or XPO1) mediated export of viral proteins critical for RSV and influenza pathogenesis; and (2) repress nuclear factor κB (NF-κB) activation, thus reducing cytokine production and eliminating virus-associated immunopathology. The repurposing of SINE compounds as antivirals shows promise not only against RSV and influenza virus but also against other viruses that exploit the nucleus as part of their viral life cycle.
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Affiliation(s)
- Jennifer A Pickens
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
| | - Ralph A Tripp
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
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232
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Cabot B, Cabot RA. Chromatin remodeling in mammalian embryos. Reproduction 2018; 155:R147-R158. [PMID: 29339454 DOI: 10.1530/rep-17-0488] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 01/12/2018] [Indexed: 12/28/2022]
Abstract
The mammalian embryo undergoes a dramatic amount of epigenetic remodeling during the first week of development. In this review, we discuss several epigenetic changes that happen over the course of cleavage development, focusing on covalent marks (e.g., histone methylation and acetylation) and non-covalent remodeling (chromatin remodeling via remodeling complexes; e.g., SWI/SNF-mediated chromatin remodeling). Comparisons are also drawn between remodeling events that occur in embryos from a variety of mammalian species.
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Affiliation(s)
- Birgit Cabot
- Department of Animal SciencesPurdue University, West Lafayette, Indiana, USA
| | - Ryan A Cabot
- Department of Animal SciencesPurdue University, West Lafayette, Indiana, USA
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233
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Daniels G, Zhang X, Zhong X, Santiago L, Wang LH, Wu X, Zhang JY, Liang F, Li X, Neubert TA, Steinke L, Shen Y, Basch R, Schneider R, Levy DE, Lee P. Cytoplasmic, full length and novel cleaved variant, TBLR1 reduces apoptosis in prostate cancer under androgen deprivation. Oncotarget 2018; 7:39556-39571. [PMID: 27127173 PMCID: PMC5129953 DOI: 10.18632/oncotarget.9005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 03/28/2016] [Indexed: 01/28/2023] Open
Abstract
TBLR1/TBL1XR1, a core component of the nuclear receptor corepressor (NCoR) complex critical for the regulation of multiple nuclear receptors, is a transcriptional coactivator of androgen receptor (AR) and functions as a tumor suppressor when expressed in the nucleus in prostate. Subcellular localization of a protein is critical for its function, and although TBLR1, as a transcriptional cofactor, has been primarily viewed as a nuclear protein, many cells also express variable levels of cytoplasmic TBLR1 and its cytoplasmic specific functions have not been studied. Prostate cancer (PCa) cells express moderately higher level of cytoplasmic TBLR1 compared to benign prostate cells. When comparing androgen-dependent (AD) to androgen-independent (AI) PCa, AI cells contain very high levels of TBLR1 cytoplasmic expression and low levels of nuclear expression. Overexpression of cytoplasmic TBLR1 in AD cells inhibits apoptosis induced by androgen deprivation therapy, either in an androgen free condition or in the presence of bicalutamide. Additionally, we identified a cytoplasmic specific isoform of TBLR1 (cvTBLR1) approximately 5 kDa lower in molecular weight, that is expressed at higher levels in AI PCa cells. By immunoprecipitation, we purified cvTBLR1 and using mass spectrometry analysis combined with N-terminal TMPP labeling and Edman degradation, we identified the cleavage site of cvTBLR1 at amino acid 89, truncating the first 88 amino acids of the N-terminus of the full length protein. Functionally, cvTBLR1 expressed in the cytoplasm reduced apoptosis in PCa cells and promoted growth, migration, and invasion. Finally, we identified a nuclear export signal sequence for TBLR1 cellular localization by deletion and site-directed mutagenesis. The roles of TBLR1 and cvTBLR1 provide novel insights into the mechanism of castration resistance and new strategies for PCa therapy.
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Affiliation(s)
- Garrett Daniels
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Xinmin Zhang
- Department of Pathology and Laboratory Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, NY, USA
| | - Xuelin Zhong
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Larion Santiago
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Ling Hang Wang
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Xinyu Wu
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Jack Y Zhang
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Fengxia Liang
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Xin Li
- Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY, USA
| | - Thomas A Neubert
- Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Laurey Steinke
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Ying Shen
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Ross Basch
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Robert Schneider
- Microbiology and Molecular Pathogenesis, New York University School of Medicine, New York, NY, USA
| | - David E Levy
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Peng Lee
- Department of Pathology, New York University School of Medicine, New York, NY, USA.,Department of Urology, New York University School of Medicine, New York, NY, USA.,NYU Cancer Institute, New York University School of Medicine, New York, NY, USA.,New York Harbor Healthcare System, New York University School of Medicine, New York, NY, USA
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234
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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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235
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Trifonova RT, Barteneva NS. Quantitation of IRF3 Nuclear Translocation in Heterogeneous Cellular Populations from Cervical Tissue Using Imaging Flow Cytometry. Methods Mol Biol 2018; 1745:125-153. [PMID: 29476467 DOI: 10.1007/978-1-4939-7680-5_8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Imaging flow cytometry (IFC) has become a powerful tool for studying the activation of transcriptional factors in heterogeneous cell populations in high-content imaging mode. With considerable interest to the clinical development of IFC, the question becomes how we can accelerate its application to solid tissues. We developed the first IFC-based procedure to quantify the nuclear translocation of interferon regulatory factor (IRF) 3, an important measure of induction of type I interferon antiviral response, in primary human immune cells including in solid tissues. After tissue digestion and protocol optimization by spectral flow cytometry, cell suspension is stained for intracellular IRF3 and acquired by IFC. Image analysis is performed using an optimized nuclear mask and similarity score parameter to correlate the location of IRF3 staining and a nuclear dye. The technique measures IRF3 activation at a single cell level and can detect small changes in the percent of activated cells providing objective quantitative data for statistical analysis.
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Affiliation(s)
- Radiana T Trifonova
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA.
| | - Natasha S Barteneva
- PCMM-Harvard Medical School, Boston Children's Hospital, Boston, MA, USA.
- Department of Biology, School of Sciences and Technology, Nazarbayev University, Astana, Kazakhstan.
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236
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Tan PS, Lemke EA. Probing Differential Binding Mechanisms of Phenylalanine-Glycine-Rich Nucleoporins by Single-Molecule FRET. Methods Enzymol 2018; 611:327-346. [PMID: 30471692 PMCID: PMC7611734 DOI: 10.1016/bs.mie.2018.08.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Phenylalanine-glycine-rich nucleoporins (FG-Nups) are intrinsically disordered proteins, constituting the selective barrier of the nuclear pore complex. They are highly dynamic under physiological conditions and studying their interaction with nuclear transport receptors (NTRs) is key to understanding the molecular mechanism of nucleocytoplasmic transport. Distinct conformational features of FG-Nups interacting with diverse NTRs can be detected by multiparameter single-molecule fluorescence energy transfer (smFRET), which is a powerful technique for studying the dynamics and interactions of biomolecules in solution. Here we provide a detailed protocol utilizing smFRET to reveal differential binding mechanisms of FG-Nups to NTRs, with a focus on practical considerations on sample preparation of unglycosylated and glycosylated FG-Nups, site-specific dual-labeling, smFRET measurements, and data analysis.
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Affiliation(s)
- Piau Siong Tan
- Structural and Computational Biology Unit & Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Edward A. Lemke
- Structural and Computational Biology Unit & Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany,Biocenter, Departments of Biology and Chemistry, Pharmacy and Geosciences, Johannes Gutenberg-University Mainz, Mainz, Germany,Institute of Molecular Biology (IMB), Mainz, Germany,Corresponding author:
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237
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Luo W, Zhang J, Liang L, Wang G, Li Q, Zhu P, Zhou Y, Li J, Zhao Y, Sun N, Huang S, Zhou C, Chang Y, Cui P, Chen P, Jiang Y, Deng G, Bu Z, Li C, Jiang L, Chen H. Phospholipid scramblase 1 interacts with influenza A virus NP, impairing its nuclear import and thereby suppressing virus replication. PLoS Pathog 2018; 14:e1006851. [PMID: 29352288 PMCID: PMC5792031 DOI: 10.1371/journal.ppat.1006851] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 01/31/2018] [Accepted: 01/03/2018] [Indexed: 12/21/2022] Open
Abstract
Transcription and replication of the influenza A virus (IAV) genome occur in the nucleus of infected cells and are carried out by the viral ribonucleoprotein complex (vRNP). As a major component of the vRNP complex, the viral nucleoprotein (NP) mediates the nuclear import of the vRNP complex via its nuclear localization signals (NLSs). Clearly, an effective way for the host to antagonize IAV infection would be by targeting vRNP nuclear import. Here, we identified phospholipid scramblase 1 (PLSCR1) as a binding partner of NP by using a yeast two-hybrid (Y2H) screen. The interaction between NP and PLSCR1 in mammalian cells was demonstrated by using co-immunoprecipitation and pull-down assays. We found that the stable overexpression of PLSCR1 suppressed the nuclear import of NP, hindered the virus life cycle, and significantly inhibited the replication of various influenza subtypes. In contrast, siRNA knockdown or CRISPR/Cas9 knockout of PLSCR1 increased virus propagation. Further analysis indicated that the inhibitory effect of PLSCR1 on the nuclear import of NP was not caused by affecting the phosphorylation status of NP or by stimulating the interferon (IFN) pathways. Instead, PLSCR1 was found to form a trimeric complex with NP and members of the importin α family, which inhibited the incorporation of importin β, a key mediator of the classical nuclear import pathway, into the complex, thus impairing the nuclear import of NP and suppressing virus replication. Our results demonstrate that PLSCR1 negatively regulates virus replication by interacting with NP in the cytoplasm and preventing its nuclear import.
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Affiliation(s)
- Weiyu Luo
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Jie Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Libin Liang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Guangwen Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Qibing Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Pengyang Zhu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yuan Zhou
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Junping Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yuhui Zhao
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Nan Sun
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Shanyu Huang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Chenchen Zhou
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yu Chang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Pengfei Cui
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Pucheng Chen
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yongping Jiang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Guohua Deng
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Zhigao Bu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Chengjun Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Li Jiang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Hualan Chen
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
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238
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Zhu Y, Wang B, Tang K, Hsu CC, Xie S, Du H, Yang Y, Tao WA, Zhu JK. An Arabidopsis Nucleoporin NUP85 modulates plant responses to ABA and salt stress. PLoS Genet 2017; 13:e1007124. [PMID: 29232718 PMCID: PMC5741264 DOI: 10.1371/journal.pgen.1007124] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/22/2017] [Accepted: 11/23/2017] [Indexed: 01/07/2023] Open
Abstract
Several nucleoporins in the nuclear pore complex (NPC) have been reported to be involved in abiotic stress responses in plants. However, the molecular mechanism of how NPC regulates abiotic stress responses, especially the expression of stress responsive genes remains poorly understood. From a forward genetics screen using an abiotic stress-responsive luciferase reporter (RD29A-LUC) in the sickle-1 (sic-1) mutant background, we identified a suppressor caused by a mutation in NUCLEOPORIN 85 (NUP85), which exhibited reduced expression of RD29A-LUC in response to ABA and salt stress. Consistently, the ABA and salinity induced expression of several stress responsive genes such as RD29A, COR15A and COR47 was significantly compromised in nup85 mutants and other nucleoporin mutants such as nup160 and hos1. Subsequently, Immunoprecipitation and mass spectrometry analysis revealed that NUP85 is potentially associated with HOS1 and other nucleoporins within the nup107-160 complex, along with several mediator subunits. We further showed that there is a direct physical interaction between MED18 and NUP85. Similar to NUP85 mutations, MED18 mutation was also found to attenuate expression of stress responsive genes. Taken together, we not only revealed the involvement of NUP85 and other nucleoporins in regulating ABA and salt stress responses, but also uncovered a potential relation between NPC and mediator complex in modulating the gene expression in plants. Nuclear pore complex (NPC) mediates the traffic between nucleus and cytoplasm. This work identified NUCLEOPORIN 85 (NUP85) as an important factor for the expression of stress-responsive luciferase reporter gene RD29A-LUC in response to ABA and salt stress from a forward genetics screen. Mutation in NUP85 and other NPC components such as NUP160 and HOS1 resulted in decreased expression of several stress responsive genes such as RD29A, COR15A and COR47. Proteomics data uncovered a list of putative NUP85 associated proteins. Furthermore, NUP85 was demonstrated to interact with MED18, a master transcriptional regulator, to control the expression of stress responsive genes. The study has added a new layer of knowledge about the diverse functions of NPC in abiotic stress responses.
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Affiliation(s)
- Yingfang Zhu
- Shanghai Center for Plant Stress Biology and CAS Center of Excellence for Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, United States of America
- * E-mail: (YZ); (JKZ)
| | - Bangshing Wang
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, United States of America
| | - Kai Tang
- Shanghai Center for Plant Stress Biology and CAS Center of Excellence for Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, United States of America
| | - Chuan-Chih Hsu
- Department of Biochemistry, Purdue University, West Lafayette, IN, United States of America
| | - Shaojun Xie
- Shanghai Center for Plant Stress Biology and CAS Center of Excellence for Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, United States of America
| | - Hai Du
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, United States of America
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China
| | - Yuting Yang
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, United States of America
- Key Laboratory of Sugarcane Biology and Genetic Breeding Ministry of Agriculture, Fujian Agriculture and Forestry University Fuzhou, Fuzhou, China
| | - Weiguo Andy Tao
- Department of Biochemistry, Purdue University, West Lafayette, IN, United States of America
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology and CAS Center of Excellence for Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, United States of America
- * E-mail: (YZ); (JKZ)
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EGFR feedback-inhibition by Ran-binding protein 6 is disrupted in cancer. Nat Commun 2017; 8:2035. [PMID: 29229958 PMCID: PMC5725448 DOI: 10.1038/s41467-017-02185-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 11/09/2017] [Indexed: 12/15/2022] Open
Abstract
Transport of macromolecules through the nuclear pore by importins and exportins plays a critical role in the spatial regulation of protein activity. How cancer cells co-opt this process to promote tumorigenesis remains unclear. The epidermal growth factor receptor (EGFR) plays a critical role in normal development and in human cancer. Here we describe a mechanism of EGFR regulation through the importin β family member RAN-binding protein 6 (RanBP6), a protein of hitherto unknown functions. We show that RanBP6 silencing impairs nuclear translocation of signal transducer and activator of transcription 3 (STAT3), reduces STAT3 binding to the EGFR promoter, results in transcriptional derepression of EGFR, and increased EGFR pathway output. Focal deletions of the RanBP6 locus on chromosome 9p were found in a subset of glioblastoma (GBM) and silencing of RanBP6 promoted glioma growth in vivo. Our results provide an example of EGFR deregulation in cancer through silencing of components of the nuclear import pathway.
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240
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Chen WG, Witten J, Grindy SC, Holten-Andersen N, Ribbeck K. Charge Influences Substrate Recognition and Self-Assembly of Hydrophobic FG Sequences. Biophys J 2017; 113:2088-2099. [PMID: 29117531 DOI: 10.1016/j.bpj.2017.08.058] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 08/08/2017] [Accepted: 08/29/2017] [Indexed: 01/19/2023] Open
Abstract
The nuclear pore complex controls the passage of molecules via hydrophobic phenylalanine-glycine (FG) domains on nucleoporins. Such FG domains consist of repeating units of FxFG, FG, or GLFG sequences, many of which are interspersed with highly charged amino acid sequences. Despite the high density of charge in certain FG domains, if and how charge influences FG-domain self-assembly and selective binding of nuclear transport receptors is largely unexplored. Using rationally designed short peptide sequences, we determined that the charge type and identity of amino acids surrounding FG sequences impact the structure and selectivity of FG-based gels. Moreover, we showed that spatial localization of the charged amino acids with respect to the FG sequence determines the degree to which charge influences hydrophobic interactions. Taken together, our study highlights that charge type and placement of amino acids regulate FG-sequence function and are important considerations when studying the mechanism of nuclear pore complex transport in vivo.
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Affiliation(s)
- Wesley G Chen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Jacob Witten
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; Computational Systems Biology Initiative, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Scott C Grindy
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Niels Holten-Andersen
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Katharina Ribbeck
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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241
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Gribko A, Hahlbrock A, Strieth S, Becker S, Hagemann J, Deichelbohrer M, Hildebrandt A, Habtemichael N, Wünsch D. Disease-relevant signalling-pathways in head and neck cancer: Taspase1's proteolytic activity fine-tunes TFIIA function. Sci Rep 2017; 7:14937. [PMID: 29097782 PMCID: PMC5668323 DOI: 10.1038/s41598-017-14814-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/16/2017] [Indexed: 12/23/2022] Open
Abstract
Head and neck cancer (HNC) is the seventh most common malignancy in the world and its prevailing form, the head and neck squamous cell carcinoma (HNSCC), is characterized as aggressive and invasive cancer type. The transcription factor II A (TFIIA), initially described as general regulator of RNA polymerase II-dependent transcription, is part of complex transcriptional networks also controlling mammalian head morphogenesis. Posttranslational cleavage of the TFIIA precursor by the oncologically relevant protease Taspase1 is crucial in this process. In contrast, the relevance of Taspase1-mediated TFIIA cleavage during oncogenesis of HNSCC is not characterized yet. Here, we performed genome-wide expression profiling of HNSCC which revealed significant downregulation of the TFIIA downstream target CDKN2A. To identify potential regulatory mechanisms of TFIIA on cellular level, we characterized nuclear-cytoplasmic transport and Taspase1-mediated cleavage of TFIIA variants. Unexpectedly, we identified an evolutionary conserved nuclear export signal (NES) counteracting nuclear localization and thus, transcriptional activity of TFIIA. Notably, proteolytic processing of TFIIA by Taspase1 was found to mask the NES, thereby promoting nuclear localization and transcriptional activation of TFIIA target genes, such as CDKN2A. Collectively, we here describe a hitherto unknown mechanism how cellular localization and Taspase1 cleavage fine-tunes transcriptional activity of TFIIA in HNSCC.
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Affiliation(s)
- Alena Gribko
- Department of Otorhinolaryngology, Molecular and Cellular Oncology, University Hospital of Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany
| | - Angelina Hahlbrock
- Department of Otorhinolaryngology, Molecular and Cellular Oncology, University Hospital of Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany
| | - Sebastian Strieth
- Department of Otorhinolaryngology, Molecular and Cellular Oncology, University Hospital of Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany
| | - Sven Becker
- Department of Otorhinolaryngology, Molecular and Cellular Oncology, University Hospital of Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany
| | - Jan Hagemann
- Department of Otorhinolaryngology, Molecular and Cellular Oncology, University Hospital of Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany
| | - Max Deichelbohrer
- Department of Otorhinolaryngology, Molecular and Cellular Oncology, University Hospital of Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany
| | - Andreas Hildebrandt
- Scientific Computing and Bioinformatics, Johannes Gutenberg University, Staudingerweg 9, Mainz, 55128, Germany
| | - Negusse Habtemichael
- Department of Otorhinolaryngology, Molecular and Cellular Oncology, University Hospital of Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany
| | - D Wünsch
- Department of Otorhinolaryngology, Molecular and Cellular Oncology, University Hospital of Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany.
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242
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Mirallas O, Ballega E, Samper-Martín B, García-Márquez S, Carballar R, Ricco N, Jiménez J, Clotet J. Intertwined control of the cell cycle and nucleocytoplasmic transport by the cyclin-dependent kinase Pho85 and RanGTPase Gsp1 in Saccharomyces cerevisiae. Microbiol Res 2017; 206:168-176. [PMID: 29146254 DOI: 10.1016/j.micres.2017.10.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/09/2017] [Accepted: 10/17/2017] [Indexed: 10/18/2022]
Abstract
Deciphering the molecular mechanisms that connect cell cycle progression and nucleocytoplasmic transport is of particular interest: this intertwined relationship, once understood, may provide useful insight on the diseases resulting from the malfunction of these processes. In the present study we report on findings that indicate a biochemical connection between the cell cycle regulator CDK Pho85 and Ran-GTPase Gsp1, an essential nucleocytoplasmic transport component. When Gsp1 cannot be phosphorylated by Pho85, the cell cycle progression is impaired. Accordingly, a nonphosphorylatable version of Gsp1 abnormally localizes to the nucleus, which impairs the nuclear transport of molecules, including key components of cell cycle progression. Furthermore, our results suggest that the physical interaction of Gsp1 and the Kap95 karyopherin, essential to the release of nuclear cargoes, is altered. Altogether, the present findings point to the involvement of a biochemical mechanism in the interlocked regulation of the cell cycle and nuclear transport.
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Affiliation(s)
- Oriol Mirallas
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Elisabet Ballega
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Bàrbara Samper-Martín
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Sergio García-Márquez
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Reyes Carballar
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Natalia Ricco
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain
| | - Javier Jiménez
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain.
| | - Josep Clotet
- Department of Basic Sciences, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Barcelona, Spain.
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243
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Jacobs SC, Taylor A, Herrero LJ, Mahalingam S, Fazakerley JK. Mutation of a Conserved Nuclear Export Sequence in Chikungunya Virus Capsid Protein Disrupts Host Cell Nuclear Import. Viruses 2017; 9:E306. [PMID: 29053568 PMCID: PMC5691657 DOI: 10.3390/v9100306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/17/2017] [Accepted: 10/17/2017] [Indexed: 11/17/2022] Open
Abstract
Transmitted by mosquitoes; chikungunya virus (CHIKV) is responsible for frequent outbreaks of arthritic disease in humans. CHIKV is an arthritogenic alphavirus of the Togaviridae family. Capsid protein, a structural protein encoded by the CHIKV RNA genome, is able to translocate to the host cell nucleus. In encephalitic alphaviruses nuclear translocation induces host cell shut off; however, the role of capsid protein nuclear localisation in arthritogenic alphaviruses remains unclear. Using replicon systems, we investigated a nuclear export sequence (NES) in the N-terminal region of capsid protein; analogous to that found in encephalitic alphavirus capsid but uncharacterised in CHIKV. The chromosomal maintenance 1 (CRM1) export adaptor protein mediated CHIKV capsid protein export from the nucleus and a region within the N-terminal part of CHIKV capsid protein was required for active nuclear targeting. In contrast to encephalitic alphaviruses, CHIKV capsid protein did not inhibit host nuclear import; however, mutating the NES of capsid protein (∆NES) blocked host protein access to the nucleus. Interactions between capsid protein and the nucleus warrant further investigation.
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Affiliation(s)
- Susan C Jacobs
- The Roslin Institute, The University of Edinburgh, Midlothian EH25 9RG, UK.
| | - Adam Taylor
- Institute for Glycomics, Gold Coast Campus, Griffith University, Nathan, QLD 4212, Australia.
| | - Lara J Herrero
- Institute for Glycomics, Gold Coast Campus, Griffith University, Nathan, QLD 4212, Australia.
| | - Suresh Mahalingam
- Institute for Glycomics, Gold Coast Campus, Griffith University, Nathan, QLD 4212, Australia.
| | - John K Fazakerley
- The Roslin Institute, The University of Edinburgh, Midlothian EH25 9RG, UK.
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244
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An S, Yoon J, Kim H, Song JJ, Cho US. Structure-based nuclear import mechanism of histones H3 and H4 mediated by Kap123. eLife 2017; 6:30244. [PMID: 29035199 PMCID: PMC5677370 DOI: 10.7554/elife.30244] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 10/12/2017] [Indexed: 01/03/2023] Open
Abstract
Kap123, a major karyopherin protein of budding yeast, recognizes the nuclear localization signals (NLSs) of cytoplasmic histones H3 and H4 and translocates them into the nucleus during DNA replication. Mechanistic questions include H3- and H4-NLS redundancy toward Kap123 and the role of the conserved diacetylation of cytoplasmic H4 (K5ac and K12ac) in Kap123-mediated histone nuclear translocation. Here, we report crystal structures of full-length Kluyveromyces lactis Kap123 alone and in complex with H3- and H4-NLSs. Structures reveal the unique feature of Kap123 that possesses two discrete lysine-binding pockets for NLS recognition. Structural comparison illustrates that H3- and H4-NLSs share at least one of two lysine-binding pockets, suggesting that H3- and H4-NLSs are mutually exclusive. Additionally, acetylation of key lysine residues at NLS, particularly H4-NLS diacetylation, weakens the interaction with Kap123. These data support that cytoplasmic histone H4 diacetylation weakens the Kap123-H4-NLS interaction thereby facilitating histone Kap123-H3-dependent H3:H4/Asf1 complex nuclear translocation.
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Affiliation(s)
- Sojin An
- Department of Biological Chemistry, University of Michigan Medical School, Michigan, United States
| | - Jungmin Yoon
- Structural Biology Laboratory of Epigenetics, Department of Biological Sciences, Graduate school of Nanoscience and Technology (World Class University), KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Hanseong Kim
- Department of Biological Chemistry, University of Michigan Medical School, Michigan, United States
| | - Ji-Joon Song
- Structural Biology Laboratory of Epigenetics, Department of Biological Sciences, Graduate school of Nanoscience and Technology (World Class University), KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Uhn-Soo Cho
- Department of Biological Chemistry, University of Michigan Medical School, Michigan, United States
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245
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Cai M, Huang Z, Liao Z, Chen T, Wang P, Jiang S, Chen D, Peng T, Bian Y, Hong G, Yang H, Zeng Z, Li X, Li M. Characterization of the subcellular localization and nuclear import molecular mechanisms of herpes simplex virus 1 UL2. Biol Chem 2017; 398:509-517. [PMID: 27865090 DOI: 10.1515/hsz-2016-0268] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Accepted: 11/16/2016] [Indexed: 11/15/2022]
Abstract
As a crucial protein, the herpes simplex virus 1 (HSV-1) UL2 protein has been shown to take part in various stages of viral infection, nonetheless, its exact subcellular localization and transport molecular determinants are not well known thus far. In the present study, by using live cells fluorescent microscopy assay, UL2 tagged with enhanced yellow fluorescent protein was transiently expressed in live cells and showed a completely nuclear accumulation without the presence of other HSV-1 proteins. Moreover, the nuclear transport of UL2 was characterized to be assisted by multiple transport pathways through Ran-, importin α1-, α5-, α7-, β1- and transportin-1 cellular transport receptors. Consequently, these results will improve understanding of UL2-mediated biological functions in HSV-1 infection cycles.
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246
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Koyama M, Hirano H, Shirai N, Matsuura Y. Crystal structure of the Xpo1p nuclear export complex bound to the SxFG/PxFG repeats of the nucleoporin Nup42p. Genes Cells 2017; 22:861-875. [PMID: 28791779 DOI: 10.1111/gtc.12520] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/07/2017] [Indexed: 12/01/2022]
Abstract
Xpo1p (yeast CRM1) is the major nuclear export receptor that carries a plethora of proteins and ribonucleoproteins from the nucleus to cytoplasm. The passage of the Xpo1p nuclear export complex through nuclear pore complexes (NPCs) is facilitated by interactions with nucleoporins (Nups) containing extensive repeats of phenylalanine-glycine (so-called FG repeats), although the precise role of each Nup in the nuclear export reaction remains incompletely understood. Here we report structural and biochemical characterization of the interactions between the Xpo1p nuclear export complex and the FG repeats of Nup42p, a nucleoporin localized at the cytoplasmic face of yeast NPCs and has characteristic SxFG/PxFG sequence repeat motif. The crystal structure of Xpo1p-PKI-Nup42p-Gsp1p-GTP complex identified three binding sites for the SxFG/PxFG repeats on HEAT repeats 14-20 of Xpo1p. Mutational analyses of Nup42p showed that the conserved serines and prolines in the SxFG/PxFG repeats contribute to Xpo1p-Nup42p binding. Our structural and biochemical data suggest that SxFG/PxFG-Nups such as Nup42p and Nup159p at the cytoplasmic face of NPCs provide high-affinity docking sites for the Xpo1p nuclear export complex in the terminal stage of NPC passage and that subsequent disassembly of the nuclear export complex facilitates recycling of free Xpo1p back to the nucleus.
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Affiliation(s)
- Masako Koyama
- Division of Biological Science, Nagoya University, Nagoya, 464-8602, Japan
| | - Hidemi Hirano
- Division of Biological Science, Nagoya University, Nagoya, 464-8602, Japan
| | - Natsuki Shirai
- Division of Biological Science, Nagoya University, Nagoya, 464-8602, Japan
| | - Yoshiyuki Matsuura
- Division of Biological Science, Nagoya University, Nagoya, 464-8602, Japan
- Structural Biology Research Center, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan
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247
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Dewenter M, von der Lieth A, Katus HA, Backs J. Calcium Signaling and Transcriptional Regulation in Cardiomyocytes. Circ Res 2017; 121:1000-1020. [DOI: 10.1161/circresaha.117.310355] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Calcium (Ca
2+
) is a universal regulator of various cellular functions. In cardiomyocytes, Ca
2+
is the central element of excitation–contraction coupling, but also impacts diverse signaling cascades and influences the regulation of gene expression, referred to as excitation–transcription coupling. Disturbances in cellular Ca
2+
-handling and alterations in Ca
2+
-dependent gene expression patterns are pivotal characteristics of failing cardiomyocytes, with several excitation–transcription coupling pathways shown to be critically involved in structural and functional remodeling processes. Thus, targeting Ca
2+
-dependent transcriptional pathways might offer broad therapeutic potential. In this article, we (1) review cytosolic and nuclear Ca
2+
dynamics in cardiomyocytes with respect to their impact on Ca
2+
-dependent signaling, (2) give an overview on Ca
2+
-dependent transcriptional pathways in cardiomyocytes, and (3) discuss implications of excitation–transcription coupling in the diseased heart.
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Affiliation(s)
- Matthias Dewenter
- From the Department of Molecular Cardiology and Epigenetics (M.D., A.v.d.L., J.B.) and Department of Cardiology (H.A.K.), Heidelberg University, Germany; and DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany (M.D., A.v.d.L., H.A.K., J.B.)
| | - Albert von der Lieth
- From the Department of Molecular Cardiology and Epigenetics (M.D., A.v.d.L., J.B.) and Department of Cardiology (H.A.K.), Heidelberg University, Germany; and DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany (M.D., A.v.d.L., H.A.K., J.B.)
| | - Hugo A. Katus
- From the Department of Molecular Cardiology and Epigenetics (M.D., A.v.d.L., J.B.) and Department of Cardiology (H.A.K.), Heidelberg University, Germany; and DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany (M.D., A.v.d.L., H.A.K., J.B.)
| | - Johannes Backs
- From the Department of Molecular Cardiology and Epigenetics (M.D., A.v.d.L., J.B.) and Department of Cardiology (H.A.K.), Heidelberg University, Germany; and DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany (M.D., A.v.d.L., H.A.K., J.B.)
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248
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Wang W, Subramani S. Role of PEX5 ubiquitination in maintaining peroxisome dynamics and homeostasis. Cell Cycle 2017; 16:2037-2045. [PMID: 28933989 PMCID: PMC5731411 DOI: 10.1080/15384101.2017.1376149] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 08/24/2017] [Accepted: 09/01/2017] [Indexed: 12/15/2022] Open
Abstract
Peroxisomes are essential and dynamic organelles that allow cells to rapidly adapt and cope with changing environments and/or physiological conditions by modulation of both peroxisome biogenesis and turnover. Peroxisome biogenesis involves the assembly of peroxisome membranes and the import of peroxisomal matrix proteins. The latter depends on the receptor, PEX5, which recognizes peroxisomal matrix proteins in the cytosol directly or indirectly, and transports them to the peroxisomal lumen. In this review, we discuss the role of PEX5 ubiquitination in both peroxisome biogenesis and turnover, specifically in PEX5 receptor recycling, stability and abundance, as well as its role in pexophagy (autophagic degradation of peroxisomes).
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Affiliation(s)
- Wei Wang
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
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249
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Gao FB, Almeida S, Lopez-Gonzalez R. Dysregulated molecular pathways in amyotrophic lateral sclerosis-frontotemporal dementia spectrum disorder. EMBO J 2017; 36:2931-2950. [PMID: 28916614 DOI: 10.15252/embj.201797568] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/15/2017] [Accepted: 08/30/2017] [Indexed: 12/11/2022] Open
Abstract
Frontotemporal dementia (FTD), the second most common form of dementia in people under 65 years of age, is characterized by progressive atrophy of the frontal and/or temporal lobes. FTD overlaps extensively with the motor neuron disease amyotrophic lateral sclerosis (ALS), especially at the genetic level. Both FTD and ALS can be caused by many mutations in the same set of genes; the most prevalent of these mutations is a GGGGCC repeat expansion in the first intron of C9ORF72 As shown by recent intensive studies, some key cellular pathways are dysregulated in the ALS-FTD spectrum disorder, including autophagy, nucleocytoplasmic transport, DNA damage repair, pre-mRNA splicing, stress granule dynamics, and others. These exciting advances reveal the complexity of the pathogenic mechanisms of FTD and ALS and suggest promising molecular targets for future therapeutic interventions in these devastating disorders.
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Affiliation(s)
- Fen-Biao Gao
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Sandra Almeida
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
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250
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Pulupa J, Rachh M, Tomasini MD, Mincer JS, Simon SM. A coarse-grained computational model of the nuclear pore complex predicts Phe-Gly nucleoporin dynamics. J Gen Physiol 2017; 149:951-966. [PMID: 28887410 PMCID: PMC5694938 DOI: 10.1085/jgp.201711769] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 06/27/2017] [Accepted: 08/10/2017] [Indexed: 11/25/2022] Open
Abstract
The phenylalanine-glycine–repeat nucleoporins are essential for transport through the nuclear pore complex. Pulupa et al. observe reptation of these nucleoporins on a physiological timescale in coarse-grained computational simulations. The phenylalanine-glycine–repeat nucleoporins (FG-Nups), which occupy the lumen of the nuclear pore complex (NPC), are critical for transport between the nucleus and cytosol. Although NPCs differ in composition across species, they are largely conserved in organization and function. Transport through the pore is on the millisecond timescale. Here, to explore the dynamics of nucleoporins on this timescale, we use coarse-grained computational simulations. These simulations generate predictions that can be experimentally tested to distinguish between proposed mechanisms of transport. Our model reflects the conserved structure of the NPC, in which FG-Nup filaments extend into the lumen and anchor along the interior of the channel. The lengths of the filaments in our model are based on the known characteristics of yeast FG-Nups. The FG-repeat sites also bind to each other, and we vary this association over several orders of magnitude and run 100-ms simulations for each value. The autocorrelation functions of the orientation of the simulated FG-Nups are compared with in vivo anisotropy data. We observe that FG-Nups reptate back and forth through the NPC at timescales commensurate with experimental measurements of the speed of cargo transport through the NPC. Our results are consistent with models of transport where FG-Nup filaments are free to move across the central channel of the NPC, possibly informing how cargo might transverse the NPC.
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Affiliation(s)
- Joan Pulupa
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, NY
| | - Manas Rachh
- Courant Institute of Mathematical Sciences, New York, NY
| | - Michael D Tomasini
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, NY
| | - Joshua S Mincer
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, NY .,Department of Anesthesiology, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Sanford M Simon
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, NY
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