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Mediouni S, Kessing CF, Jablonski JA, Thenin-Houssier S, Clementz M, Kovach MD, Mousseau G, de Vera IMS, Li C, Kojetin DJ, Evans DT, Valente ST. The Tat inhibitor didehydro-cortistatin A suppresses SIV replication and reactivation. FASEB J 2019; 33:8280-8293. [PMID: 31021670 DOI: 10.1096/fj.201801165r] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The HIV-1 transactivation protein (Tat) binds the HIV mRNA transactivation responsive element (TAR), regulating transcription and reactivation from latency. Drugs against Tat are unfortunately not clinically available. We reported that didehydro-cortistatin A (dCA) inhibits HIV-1 Tat activity. In human CD4+ T cells isolated from aviremic individuals and in the humanized mouse model of latency, combining dCA with antiretroviral therapy accelerates HIV-1 suppression and delays viral rebound upon treatment interruption. This drug class is amenable to block-and-lock functional cure approaches, aimed at a durable state of latency. Simian immunodeficiency virus (SIV) infection of rhesus macaques (RhMs) is the best-characterized model for AIDS research. Here, we demonstrate, using in vitro and cell-based assays, that dCA directly binds to SIV Tat's basic domain. dCA specifically inhibits SIV Tat binding to TAR, but not a Tat-Rev fusion protein, which activates transcription when Rev binds to its cognate RNA binding site replacing the apical region of TAR. Tat-TAR inhibition results in loss of RNA polymerase II recruitment to the SIV promoter. Importantly, dCA potently inhibits SIV reactivation from latently infected Hut78 cells and from primary CD4+ T cells explanted from SIVmac239-infected RhMs. In sum, dCA's remarkable breadth of activity encourages SIV-infected RhM use for dCA preclinical evaluation.-Mediouni, S., Kessing, C. F., Jablonski, J. A., Thenin-Houssier, S., Clementz, M., Kovach, M. D., Mousseau, G., de Vera, I.M.S., Li, C., Kojetin, D. J., Evans, D. T., Valente, S. T. The Tat inhibitor didehydro-cortistatin A suppresses SIV replication and reactivation.
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Affiliation(s)
- Sonia Mediouni
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Cari F Kessing
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Joseph A Jablonski
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Suzie Thenin-Houssier
- Institute of Human Genetics (IGH), CNRS-University of Montpelier, Montpelier, France
| | - Mark Clementz
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Melia D Kovach
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Guillaume Mousseau
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Ian Mitchelle S de Vera
- Department of Pharmacology and Physiology, St. Louis University School of Medicine, St. Louis, Missouri, USA
| | - Chuan Li
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Douglas J Kojetin
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida, USA
| | - David T Evans
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Susana T Valente
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, Florida, USA
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2
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Spector C, Mele AR, Wigdahl B, Nonnemacher MR. Genetic variation and function of the HIV-1 Tat protein. Med Microbiol Immunol 2019; 208:131-169. [PMID: 30834965 DOI: 10.1007/s00430-019-00583-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 02/11/2019] [Indexed: 12/14/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) encodes a transactivator of transcription (Tat) protein, which has several functions that promote viral replication, pathogenesis, and disease. Amino acid variation within Tat has been observed to alter the functional properties of Tat and, depending on the HIV-1 subtype, may produce Tat phenotypes differing from viruses' representative of each subtype and commonly used in in vivo and in vitro experimentation. The molecular properties of Tat allow for distinctive functional activities to be determined such as the subcellular localization and other intracellular and extracellular functional aspects of this important viral protein influenced by variation within the Tat sequence. Once Tat has been transported into the nucleus and becomes engaged in transactivation of the long terminal repeat (LTR), various Tat variants may differ in their capacity to activate viral transcription. Post-translational modification patterns based on these amino acid variations may alter interactions between Tat and host factors, which may positively or negatively affect this process. In addition, the ability of HIV-1 to utilize or not utilize the transactivation response (TAR) element within the LTR, based on genetic variation and cellular phenotype, adds a layer of complexity to the processes that govern Tat-mediated proviral DNA-driven transcription and replication. In contrast, cytoplasmic or extracellular localization of Tat may cause pathogenic effects in the form of altered cell activation, apoptosis, or neurotoxicity. Tat variants have been shown to differentially induce these processes, which may have implications for long-term HIV-1-infected patient care in the antiretroviral therapy era. Future studies concerning genetic variation of Tat with respect to function should focus on variants derived from HIV-1-infected individuals to efficiently guide Tat-targeted therapies and elucidate mechanisms of pathogenesis within the global patient population.
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Affiliation(s)
- Cassandra Spector
- Department of Microbiology and Immunology, Drexel University College of Medicine, 245 N 15th St, Philadelphia, PA, 19102, USA
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Anthony R Mele
- Department of Microbiology and Immunology, Drexel University College of Medicine, 245 N 15th St, Philadelphia, PA, 19102, USA
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Brian Wigdahl
- Department of Microbiology and Immunology, Drexel University College of Medicine, 245 N 15th St, Philadelphia, PA, 19102, USA
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael R Nonnemacher
- Department of Microbiology and Immunology, Drexel University College of Medicine, 245 N 15th St, Philadelphia, PA, 19102, USA.
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, USA.
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA.
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3
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Goh Y, Song YH, Lee G, Bae H, Mahata MK, Lee KT. Cellular uptake efficiency of nanoparticles investigated by three-dimensional imaging. Phys Chem Chem Phys 2018; 20:11359-11368. [PMID: 29644351 DOI: 10.1039/c8cp00493e] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Understanding the interaction of nanoparticles with living cells on the basis of cellular uptake efficiency is a fundamental requisite in biomedical research. Cellular internalization of nanoparticles takes place by mechanisms like ATP hydrolysis-driven endocytosis that deliver nanoparticles to the cytoplasm, organelles and nuclei. Despite its importance in nanomedicine, this uptake procedure is not understood in-depth because of the complexity of the biochemical mechanisms and the lack of available experimental methods for quantitative analysis. The only breakthrough is likely to be the development of imaging techniques that can visualize, monitor and even count the number of nanoparticles inside the cell. To this end, we report here a new, fast and background-free three-dimensional (3-D) imaging technique with quantitative evaluation of the uptake efficiency for NaYF4:Yb3+,Er3+/NaYF4 core/shell upconversion nanoparticles (UCNPs) functionalized with different chemical and biological groups. Furthermore, the multiple 3-D trajectories of the UCNPs have been analyzed to investigate the cellular dynamics. This study reveals the nuclear uptake of UCNPs to be dependent on the specific chemical groups conjugated to the UCNPs. The developed 3-D imaging technique is of great significance for exploring complex biological systems.
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Affiliation(s)
- Yeongchang Goh
- Department of Chemistry, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Korea.
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4
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A Copper(II) Phenanthroline Metallopeptide That Targets and Disrupts Mitochondrial Function in Breast Cancer Stem Cells. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201710910] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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5
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Laws K, Bineva-Todd G, Eskandari A, Lu C, O'Reilly N, Suntharalingam K. A Copper(II) Phenanthroline Metallopeptide That Targets and Disrupts Mitochondrial Function in Breast Cancer Stem Cells. Angew Chem Int Ed Engl 2017; 57:287-291. [DOI: 10.1002/anie.201710910] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Indexed: 01/01/2023]
Affiliation(s)
- Kristine Laws
- Department of Chemistry; King's College London; London SE1 1DB UK
| | | | - Arvin Eskandari
- Department of Chemistry; King's College London; London SE1 1DB UK
| | - Chunxin Lu
- Department of Chemistry; King's College London; London SE1 1DB UK
| | - Nicola O'Reilly
- Peptide Chemistry; The Francis Crick Institute; London NW1 1AT UK
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6
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Ferri G, Storti B, Bizzarri R. Nucleocytoplasmic transport in cells with progerin-induced defective nuclear lamina. Biophys Chem 2017; 229:77-83. [PMID: 28712764 DOI: 10.1016/j.bpc.2017.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/14/2017] [Accepted: 06/14/2017] [Indexed: 10/19/2022]
Abstract
Recent data indicate that nuclear lamina (NL) plays a relevant role in many fundamental cellular functions. The peculiar role of NL in cells is dramatically demonstrated by the Hutchinson-Gilford progeria syndrome (HGPS), an inherited laminopathy that causes premature, rapid aging shortly after birth. In HGPS, a mutant form of Lamin A (progeria) leads to a dysmorphic NL structure, but how this perturbation is transduced into cellular changes is still largely unknown. Owing to the close structural relationship between NL and the Nuclear Pore Complex (NPC), in this work we test whether HGPS affects passive and active nucleo-cytoplasmic shuttling of cargoes by means of an established model based of fluorescence recovery after photobleaching. Our findings clearly demonstrate that dysmorphic NL is decoupled from the dynamic characteristics of passive and active transport towards and from the nucleus, as well as from the binding affinity of transport protein mediators.
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Affiliation(s)
- Gianmarco Ferri
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127 Pisa, Italy; Center for Nanotechnology Innovation @ NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Barbara Storti
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Ranieri Bizzarri
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127 Pisa, Italy.
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7
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Cardarelli F. Time-resolved biophysical approaches to nucleocytoplasmic transport. Comput Struct Biotechnol J 2017; 15:299-306. [PMID: 28435614 PMCID: PMC5388937 DOI: 10.1016/j.csbj.2017.03.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/21/2017] [Accepted: 03/25/2017] [Indexed: 12/26/2022] Open
Abstract
Molecules are continuously shuttling across the nuclear envelope barrier that separates the nucleus from the cytoplasm. Instead of being just a barrier to diffusion, the nuclear envelope is rather a complex filter that provides eukaryotes with an elaborate spatiotemporal regulation of fundamental molecular processes, such as gene expression and protein translation. Given the highly dynamic nature of nucleocytoplasmic transport, during the past few decades large efforts were devoted to the development and application of time resolved, fluorescence-based, biophysical methods to capture the details of molecular motion across the nuclear envelope. These methods are here divided into three major classes, according to the differences in the way they report on the molecular process of nucleocytoplasmic transport. In detail, the first class encompasses those methods based on the perturbation of the fluorescence signal, also known as ensemble-averaging methods, which average the behavior of many molecules (across many pores). The second class comprises those methods based on the localization of single fluorescently-labelled molecules and tracking of their position in space and time, potentially across single pores. Finally, the third class encompasses methods based on the statistical analysis of spontaneous fluorescence fluctuations out of the equilibrium or stationary state of the system. In this case, the behavior of single molecules is probed in presence of many similarly-labelled molecules, without dwelling on any of them. Here these three classes, with their respective pros and cons as well as their main applications to nucleocytoplasmic shuttling will be briefly reviewed and discussed.
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8
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Fiume G, Di Rienzo C, Marchetti L, Pozzi D, Caracciolo G, Cardarelli F. Single-cell real-time imaging of transgene expression upon lipofection. Biochem Biophys Res Commun 2016; 474:8-14. [DOI: 10.1016/j.bbrc.2016.03.088] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 03/18/2016] [Indexed: 10/22/2022]
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9
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Musinova YR, Sheval EV, Dib C, Germini D, Vassetzky YS. Functional roles of HIV-1 Tat protein in the nucleus. Cell Mol Life Sci 2016; 73:589-601. [PMID: 26507246 PMCID: PMC11108392 DOI: 10.1007/s00018-015-2077-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 09/01/2015] [Accepted: 10/16/2015] [Indexed: 02/06/2023]
Abstract
Human immunodeficiency virus-1 (HIV-1) Tat protein is one of the most important regulatory proteins for viral gene expression in the host cell and can modulate different cellular processes. In addition, Tat is secreted by the infected cell and can be internalized by neighboring cells; therefore, it affects both infected and uninfected cells. Tat can modulate cellular processes by interacting with different cellular structures and signaling pathways. In the nucleus, Tat might be localized either in the nucleoplasm or the nucleolus depending on its concentration. Here we review the distinct functions of Tat in the nucleoplasm and the nucleolus in connection with viral infection and HIV-induced oncogenesis.
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Affiliation(s)
- Yana R Musinova
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, 119991, Moscow, Russia
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France
| | - Eugene V Sheval
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, 119991, Moscow, Russia
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France
| | - Carla Dib
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France
- UMR8126, Université Paris-Sud, CNRS, Institut de cancérologie Gustave Roussy, 94805, Villejuif, France
| | - Diego Germini
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France
- UMR8126, Université Paris-Sud, CNRS, Institut de cancérologie Gustave Roussy, 94805, Villejuif, France
| | - Yegor S Vassetzky
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, 119991, Moscow, Russia.
- LIA 1066 French-Russian Joint Cancer Research Laboratory, 94805, Villejuif, France.
- UMR8126, Université Paris-Sud, CNRS, Institut de cancérologie Gustave Roussy, 94805, Villejuif, France.
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10
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Fatin MF, Ruslinda AR, Md Arshad MK, Tee KK, Ayub RM, Hashim U, Kamarulzaman A, Gopinath SCB. HIV-1 Tat biosensor: Current development and trends for early detection strategies. Biosens Bioelectron 2015; 78:358-366. [PMID: 26655174 DOI: 10.1016/j.bios.2015.11.067] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 11/20/2015] [Accepted: 11/24/2015] [Indexed: 02/07/2023]
Abstract
Human immunodeficiency virus (HIV) has infected almost 35 million people worldwide. Various tests have been developed to detect the presence of HIV during the early stages of the disease in order to reduce the risk of transmission to other humans. The HIV-1 Tat protein is one of the proteins present in HIV that are released abundantly approximately 2-4 weeks after infection. In this review, we have outlined various strategies for detecting the Tat protein, which helps transcribe the virus and enhances replication. Detection strategies presented include immunoassays, biosensors and gene expression, which utilize antibodies or aptamers as common probes to sense the presence of Tat. Alternatively, measuring the levels of gene transcription is a direct method of analysing the HIV gene to confirm the presence of Tat. By detection of the Tat protein, virus transmission can be detected in high-risk individuals in the early stages of the disease to reduce the risk of an HIV pandemic.
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Affiliation(s)
- M F Fatin
- Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis, Kangar, 01000 Perlis, Malaysia
| | - A R Ruslinda
- Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis, Kangar, 01000 Perlis, Malaysia.
| | - M K Md Arshad
- Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis, Kangar, 01000 Perlis, Malaysia
| | - K K Tee
- Center of Excellence for Research in AIDS (CERiA), Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - R M Ayub
- Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis, Kangar, 01000 Perlis, Malaysia
| | - U Hashim
- Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis, Kangar, 01000 Perlis, Malaysia
| | - A Kamarulzaman
- Center of Excellence for Research in AIDS (CERiA), Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Subash C B Gopinath
- Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis, Kangar, 01000 Perlis, Malaysia
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11
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Spontaneous membrane-translocating peptides: influence of peptide self-aggregation and cargo polarity. Sci Rep 2015; 5:16914. [PMID: 26567719 PMCID: PMC4645181 DOI: 10.1038/srep16914] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/22/2015] [Indexed: 01/06/2023] Open
Abstract
Peptides that translocate spontaneously across cell membranes could transform the field of drug delivery by enabling the transport of otherwise membrane-impermeant molecules into cells. In this regard, a 9-aminoacid-long motif (representative sequence: PLIYLRLLR, hereafter Translocating Motif 9, TM9) that spontaneously translocates across membranes while carrying a polar dye was recently identified by high-throughput screening. Here we investigate its transport properties by a combination of in cuvette physico-chemical assays, rational mutagenesis, live-cell confocal imaging and fluorescence correlation spectroscopy measurements. We unveil TM9 ability to self-aggregate in a concentration-dependent manner and demonstrate that peptide self-aggregation is a necessary –yet not sufficient– step for effective membrane translocation. Furthermore we show that membrane crossing can occur with apolar payloads while it is completely inhibited by polar ones. These findings are discussed and compared to previous reports. The present results impose a careful rethinking of this class of sequences as direct-translocation vectors suitable for delivery purposes.
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12
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Wulan WN, Heydet D, Walker EJ, Gahan ME, Ghildyal R. Nucleocytoplasmic transport of nucleocapsid proteins of enveloped RNA viruses. Front Microbiol 2015; 6:553. [PMID: 26082769 PMCID: PMC4451415 DOI: 10.3389/fmicb.2015.00553] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/19/2015] [Indexed: 12/25/2022] Open
Abstract
Most viruses with non-segmented single stranded RNA genomes complete their life cycle in the cytoplasm of infected cells. However, despite undergoing replication in the cytoplasm, the structural proteins of some of these RNA viruses localize to the nucleus at specific times in the virus life cycle, primarily early in infection. Limited evidence suggests that this enhances successful viral replication by interfering with or inhibiting the host antiviral response. Nucleocapsid proteins of RNA viruses have a well-established, essential cytoplasmic role in virus replication and assembly. Intriguingly, nucleocapsid proteins of some RNA viruses also localize to the nucleus/nucleolus of infected cells. Their nuclear function is less well understood although significant advances have been made in recent years. This review will focus on the nucleocapsid protein of cytoplasmic enveloped RNA viruses, including their localization to the nucleus/nucleolus and function therein. A greater understanding of the nuclear localization of nucleocapsid proteins has the potential to enhance therapeutic strategies as it can be a target for the development of live-attenuated vaccines or antiviral drugs.
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Affiliation(s)
- Wahyu N Wulan
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT Australia ; Faculty of Education, Science, Technology and Mathematics, University of Canberra, Bruce, ACT Australia
| | - Deborah Heydet
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT Australia
| | - Erin J Walker
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT Australia
| | - Michelle E Gahan
- Faculty of Education, Science, Technology and Mathematics, University of Canberra, Bruce, ACT Australia
| | - Reena Ghildyal
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT Australia ; Faculty of Education, Science, Technology and Mathematics, University of Canberra, Bruce, ACT Australia
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13
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Moscatiello R, Sello S, Novero M, Negro A, Bonfante P, Navazio L. The intracellular delivery of TAT-aequorin reveals calcium-mediated sensing of environmental and symbiotic signals by the arbuscular mycorrhizal fungus Gigaspora margarita. THE NEW PHYTOLOGIST 2014; 203:1012-1020. [PMID: 24845011 DOI: 10.1111/nph.12849] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 04/10/2014] [Indexed: 06/03/2023]
Abstract
Arbuscular mycorrhiza (AM) is an ecologically relevant symbiosis between most land plants and Glomeromycota fungi. The peculiar traits of AM fungi have so far limited traditional approaches such as genetic transformation. The aim of this work was to investigate whether the protein transduction domain of the HIV-1 transactivator of transcription (TAT) protein, previously shown to act as a potent nanocarrier for macromolecule delivery in both animal and plant cells, may translocate protein cargoes into AM fungi. We evaluated the internalization into germinated spores of Gigaspora margarita of two recombinant TAT fusion proteins consisting of either a fluorescent (GFP) or a luminescent (aequorin) reporter linked to the TAT peptide. Both TAT-fused proteins were found to enter AM fungal mycelia after a short incubation period (5-10 min). Ca2+ measurements in G. margarita mycelia pre-incubated with TAT-aequorin demonstrated the occurrence of changes in the intracellular free Ca2+ concentration in response to relevant stimuli, such as touch, cold, salinity, and strigolactones, symbiosis-related plant signals. These data indicate that the cell-penetrating properties of the TAT peptide can be used as an effective strategy for intracellularly delivering proteins of interest and shed new light on Ca2+ homeostasis and signalling in AM fungi.
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Affiliation(s)
- Roberto Moscatiello
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy
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14
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Bianchini P, Cardarelli F, Luca MD, Diaspro A, Bizzarri R. Nanoscale protein diffusion by STED-based pair correlation analysis. PLoS One 2014; 9:e99619. [PMID: 24967681 PMCID: PMC4072630 DOI: 10.1371/journal.pone.0099619] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 05/17/2014] [Indexed: 11/18/2022] Open
Abstract
We describe for the first time the combination between cross-pair correlation function analysis (pair correlation analysis or pCF) and stimulated emission depletion (STED) to obtain diffusion maps at spatial resolution below the optical diffraction limit (super-resolution). Our approach was tested in systems characterized by high and low signal to noise ratio, i.e. Capsid Like Particles (CLPs) bearing several (>100) active fluorescent proteins and monomeric fluorescent proteins transiently expressed in living Chinese Hamster Ovary cells, respectively. The latter system represents the usual condition encountered in living cell studies on fluorescent protein chimeras. Spatial resolution of STED-pCF was found to be about 110 nm, with a more than twofold improvement over conventional confocal acquisition. We successfully applied our method to highlight how the proximity to nuclear envelope affects the mobility features of proteins actively imported into the nucleus in living cells. Remarkably, STED-pCF unveiled the existence of local barriers to diffusion as well as the presence of a slow component at distances up to 500-700 nm from either sides of nuclear envelope. The mobility of this component is similar to that previously described for transport complexes. Remarkably, all these features were invisible in conventional confocal mode.
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Affiliation(s)
- Paolo Bianchini
- Nanophysics, IIT—Italian Institute of Technology, Genoa, Italy
| | - Francesco Cardarelli
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
| | | | - Alberto Diaspro
- Nanophysics, IIT—Italian Institute of Technology, Genoa, Italy
| | - Ranieri Bizzarri
- Nanophysics, IIT—Italian Institute of Technology, Genoa, Italy
- NEST, Scuola Normale Superiore and Istituto Nanoscienze - CNR, Pisa, Italy
- Istituto di Biofisica – CNR, Pisa, Italy
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15
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Ponia SS, Arora S, Kumar B, Banerjea AC. Arginine rich short linear motif of HIV-1 regulatory proteins inhibits dicer dependent RNA interference. Retrovirology 2013; 10:97. [PMID: 24025624 PMCID: PMC3848888 DOI: 10.1186/1742-4690-10-97] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 08/09/2013] [Indexed: 12/29/2022] Open
Abstract
Background Arginine Rich Motif (ARM) of HIV-1 Tat and Rev are extensively studied linear motifs (LMs). They are already established as an inefficient bipartite nuclear localisation signal (NLS). The unusual passive diffusion of HIV-1 NLS tagged reporter proteins across the nucleus is due to an unknown competing functionality of ARM. Recent findings about the role of retroviral proteins as a suppressor of RNA interference (RNAi) involving their basic residues hint an interesting answer to this alternate functionality. The present work explores the role of HIV-1 ARM as a uniquely evolved viral motif to combat Dicer dependent RNAi. Results We show that RNA binding ARM of both HIV-1 Tat and Rev is a LM with a pattern RXXRRXRRR unique to viruses. Extending the in silico results to wet lab, we proved both HIV-1 Tat and Rev can suppress Dicer dependent RNA silencing process involving ARM. We show, HIV-1 Tat and Rev and their corresponding ARM can bind the RISC loading complex (RLC) components TRBP and PACT confirming ARM as an independent RNAi suppression motif. Enhancement of RNAi in infection scenario through enoxacin increases HIV-1 replication as indicated by p24 levels. Except Dicer, all other cytoplasmic RNAi components enhance HIV-1 replication, indicating crucial role of Dicer independent (Ago2 dependent) RNAi pathway in HIV-1 infection. Sequence and structural analysis of endo/exo-microRNA precursors known to be regulated in HIV-1 infection highlights differential features of microRNA biogenesis. One such set of miRNA is viral TAR encoded HIV-1-miR-TAR-5p (Tar1) and HIV-1-miR-TAR-3p (Tar2) that are known to be present throughout the HIV-1 life cycle. Our qPCR results showed that enoxacin increases Tar2 miRNA level which is interesting as Tar2 precursor shows Ago2 dependent processing features. Conclusions We establish HIV-1 ARM as a novel viral motif evolved to target the Dicer dependent RNAi pathway. The conservation of such motif in other viral proteins possibly explains the potent suppression of Dicer dependent RNAi. Our model argues that HIV-1 suppress the processing of siRNAs through inhibition of Dicer while at the same time manipulates the RNAi machinery to process miRNA involved in HIV-1 replication from Dicer independent pathways.
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Affiliation(s)
- Sanket Singh Ponia
- Virology Lab II, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
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16
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Salomone F, Cardarelli F, Signore G, Boccardi C, Beltram F. In vitro efficient transfection by CM₁₈-Tat₁₁ hybrid peptide: a new tool for gene-delivery applications. PLoS One 2013; 8:e70108. [PMID: 23922923 PMCID: PMC3726494 DOI: 10.1371/journal.pone.0070108] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 06/18/2013] [Indexed: 12/24/2022] Open
Abstract
Cell penetrating peptides (CPPs) are actively researched as non-viral molecular carriers for the controlled delivery of nucleic acids into cells, but widespread application is severely hampered by their trapping into endosomes. Here we show that the recently introduced endosomolytic CM18-Tat11 hybrid peptide (KWKLFKKIGAVLKVLTTG-YGRKKRRQRRR, residues 1-7 of Cecropin-A, 2-12 of Melittin, and 47-57 of HIV-1 Tat protein) can be exploited to obtain a self-assembled peptide-DNA vector which maintains the CM18-Tat11 ability to enter cells and destabilize vesicular membranes, concomitantly yielding high DNA transfection efficiency with no detectable cytotoxic effects. Different peptide-DNA stoichiometric ratios were tested to optimize vector size, charge, and stability characteristics. The transfection efficiency of selected candidates is quantitatively investigated by the luciferase-reporter assay. Vector intracellular trafficking is monitored in real time and in live cells by confocal microscopy. In particular, fluorescence resonant energy transfer (FRET) between suitably-labeled peptide and DNA modules was exploited to monitor complex disassembly during endocytosis, and this process is correlated to transfection timing and efficiency. We argue that these results can open the way to the rational design and application of CM18-Tat11–based systems for gene-delivery purposes.
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Affiliation(s)
- Fabrizio Salomone
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Pisa, Italy
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
| | - Francesco Cardarelli
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
- * E-mail:
| | - Giovanni Signore
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
| | - Claudia Boccardi
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
| | - Fabio Beltram
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Pisa, Italy
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
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17
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Systematic Analysis of the Functions of Lysine Acetylation in the Regulation of Tat Activity. PLoS One 2013; 8:e67186. [PMID: 23826228 PMCID: PMC3695041 DOI: 10.1371/journal.pone.0067186] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Accepted: 05/15/2013] [Indexed: 11/28/2022] Open
Abstract
The Tat protein of HIV-1 has several well-known properties, such as nucleocytoplasmic trafficking, transactivation of transcription, interaction with tubulin, regulation of mitotic progression, and induction of apoptosis. Previous studies have identified a couple of lysine residues in Tat that are essential for its functions. In order to analyze the functions of all the lysine residues in Tat, we mutated them individually to alanine, glutamine, and arginine. Through systematic analysis of the lysine mutants, we discovered several previously unidentified characteristics of Tat. We found that lysine acetylation could modulate the subcellular localization of Tat, in addition to the regulation of its transactivation activity. Our data also revealed that lysine mutations had distinct effects on microtubule assembly and Tat binding to bromodomain proteins. By correlation analysis, we further found that the effects of Tat on apoptosis and mitotic progression were not entirely attributed to its effect on microtubule assembly. Our findings suggest that Tat may regulate diverse cellular activities through binding to different proteins and that the acetylation of distinct lysine residues in Tat may modulate its interaction with various partners.
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Preventive and therapeutic effects of Smad7 on radiation-induced oral mucositis. Nat Med 2013; 19:421-8. [PMID: 23475202 PMCID: PMC3780964 DOI: 10.1038/nm.3118] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 02/04/2013] [Indexed: 12/15/2022]
Abstract
We report that K5.Smad7 mice, which express Smad7 transgene by a keratin-5 promoter, were resistant to radiation-induced oral mucositis, a painful oral ulceration. In addition to NF-κB activation known to contribute to oral mucositis, we found activated TGF-β signaling in oral mucositis. Smad7 dampened both pathways to attenuate inflammation, growth inhibition and apoptosis. Additionally, Smad7 promoted oral epithelial migration to close the wound. Further analyses revealed that TGF-β signaling Smads and their co-repressor CtBP1 transcriptionally repressed Rac1, and Smad7 abrogated this repression. Knocking down Rac1 in mouse keratinocytes abrogated Smad7-induced migration. Topically applying Smad7 protein with a cell permeable Tat-tag (Tat-Smad7) to oral mucosa showed preventive and therapeutic effects on radiation-induced oral mucositis in mice. Thus, we have identified novel molecular mechanisms involved in oral mucositis pathogenesis and our data suggest an alternative therapeutic strategy to block multiple pathological processes of oral mucositis.
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Mao AH, Lyle N, Pappu RV. Describing sequence-ensemble relationships for intrinsically disordered proteins. Biochem J 2013; 449:307-18. [PMID: 23240611 PMCID: PMC4074364 DOI: 10.1042/bj20121346] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Intrinsically disordered proteins participate in important protein-protein and protein-nucleic acid interactions and control cellular phenotypes through their prominence as dynamic organizers of transcriptional, post-transcriptional and signalling networks. These proteins challenge the tenets of the structure-function paradigm and their functional mechanisms remain a mystery given that they fail to fold autonomously into specific structures. Solving this mystery requires a first principles understanding of the quantitative relationships between information encoded in the sequences of disordered proteins and the ensemble of conformations they sample. Advances in quantifying sequence-ensemble relationships have been facilitated through a four-way synergy between bioinformatics, biophysical experiments, computer simulations and polymer physics theories. In the present review we evaluate these advances and the resultant insights that allow us to develop a concise quantitative framework for describing the sequence-ensemble relationships of intrinsically disordered proteins.
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Affiliation(s)
- Albert H. Mao
- Medical Scientist Training Program, One Brookings Drive, Campus Box 1097, St. Louis, MO 63130, U.S.A
- Computational & Molecular Biophysics Program, One Brookings Drive, Campus Box 1097, St. Louis, MO 63130, U.S.A
| | - Nicholas Lyle
- Computational & Systems Biology Program, One Brookings Drive, Campus Box 1097, St. Louis, MO 63130, U.S.A
| | - Rohit V. Pappu
- Department of Biomedical Engineering and Center for Biological Systems Engineering Washington University in St. Louis, One Brookings Drive, Campus Box 1097, St. Louis, MO 63130, U.S.A
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20
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Jarboui MA, Bidoia C, Woods E, Roe B, Wynne K, Elia G, Hall WW, Gautier VW. Nucleolar protein trafficking in response to HIV-1 Tat: rewiring the nucleolus. PLoS One 2012; 7:e48702. [PMID: 23166591 PMCID: PMC3499507 DOI: 10.1371/journal.pone.0048702] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 10/03/2012] [Indexed: 12/20/2022] Open
Abstract
The trans-activator Tat protein is a viral regulatory protein essential for HIV-1 replication. Tat trafficks to the nucleoplasm and the nucleolus. The nucleolus, a highly dynamic and structured membrane-less sub-nuclear compartment, is the site of rRNA and ribosome biogenesis and is involved in numerous cellular functions including transcriptional regulation, cell cycle control and viral infection. Importantly, transient nucleolar trafficking of both Tat and HIV-1 viral transcripts are critical in HIV-1 replication, however, the role(s) of the nucleolus in HIV-1 replication remains unclear. To better understand how the interaction of Tat with the nucleolar machinery contributes to HIV-1 pathogenesis, we investigated the quantitative changes in the composition of the nucleolar proteome of Jurkat T-cells stably expressing HIV-1 Tat fused to a TAP tag. Using an organellar proteomic approach based on mass spectrometry, coupled with Stable Isotope Labelling in Cell culture (SILAC), we quantified 520 proteins, including 49 proteins showing significant changes in abundance in Jurkat T-cell nucleolus upon Tat expression. Numerous proteins exhibiting a fold change were well characterised Tat interactors and/or known to be critical for HIV-1 replication. This suggests that the spatial control and subcellular compartimentaliation of these cellular cofactors by Tat provide an additional layer of control for regulating cellular machinery involved in HIV-1 pathogenesis. Pathway analysis and network reconstruction revealed that Tat expression specifically resulted in the nucleolar enrichment of proteins collectively participating in ribosomal biogenesis, protein homeostasis, metabolic pathways including glycolytic, pentose phosphate, nucleotides and amino acids biosynthetic pathways, stress response, T-cell signaling pathways and genome integrity. We present here the first differential profiling of the nucleolar proteome of T-cells expressing HIV-1 Tat. We discuss how these proteins collectively participate in interconnected networks converging to adapt the nucleolus dynamic activities, which favor host biosynthetic activities and may contribute to create a cellular environment supporting robust HIV-1 production.
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Affiliation(s)
- Mohamed Ali Jarboui
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Carlo Bidoia
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Elena Woods
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Barbara Roe
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Kieran Wynne
- Mass Spectrometry Resource (MSR), Conway Institute for Biomolecular and Biomedical Research, University College Dublin (UCD), Dublin, Ireland
| | - Giuliano Elia
- Mass Spectrometry Resource (MSR), Conway Institute for Biomolecular and Biomedical Research, University College Dublin (UCD), Dublin, Ireland
| | - William W. Hall
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Virginie W. Gautier
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
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Salomone F, Cardarelli F, Di Luca M, Boccardi C, Nifosì R, Bardi G, Di Bari L, Serresi M, Beltram F. A novel chimeric cell-penetrating peptide with membrane-disruptive properties for efficient endosomal escape. J Control Release 2012; 163:293-303. [DOI: 10.1016/j.jconrel.2012.09.019] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Revised: 09/21/2012] [Accepted: 09/24/2012] [Indexed: 11/30/2022]
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22
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Bizzarri R, Cardarelli F, Serresi M, Beltram F. Fluorescence recovery after photobleaching reveals the biochemistry of nucleocytoplasmic exchange. Anal Bioanal Chem 2012; 403:2339-51. [PMID: 22585053 DOI: 10.1007/s00216-012-6025-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 03/19/2012] [Accepted: 04/04/2012] [Indexed: 11/26/2022]
Abstract
Fluorescence recovery after photobleaching (FRAP) can help unveil subtle dynamical and biochemical properties of intracellular components. A peculiar aspect of this method is that it is based on the change of optical properties only, whereas dynamics and biochemistry of the molecules of interest are not perturbed. This makes FRAP particularly suitable for the study of protein translocation, e.g., between nucleus and cytoplasm. Here we present a comprehensive theoretical treatment of FRAP applied to protein nucleocytoplasmic translocation by passive diffusion and/or energy-driven processes across the nuclear envelope. Our mathematical model is validated by experimental FRAP studies with functionalized fluorescent protein chimeras. Using this approach we demonstrate that molecular crowding at the nuclear pore does not hamper passive diffusion and calculate the dimension of the nuclear pore size (5.33 nm). Additionally, our FRAP analysis reveals the biochemical parameters (maximum translocation rate and dissociation constant of the transport complex in cytoplasm) associated with the active import of a prototypical nuclear localization sequence (NLS of SV40) and related mutants. We demonstrate that transportin binding and active import into the nucleus are independent processes that can be separately modulated. The present results are discussed in light of their potential to help in engineering sequences for intracellular targeted delivery of sensors and/or therapeutic compounds. Finally, the limits of validity of our mathematical model are addressed.
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Affiliation(s)
- Ranieri Bizzarri
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Pisa, Italy.
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23
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Cardarelli F, Tosti L, Serresi M, Beltram F, Bizzarri R. Fluorescent recovery after photobleaching (FRAP) analysis of nuclear export rates identifies intrinsic features of nucleocytoplasmic transport. J Biol Chem 2011; 287:5554-61. [PMID: 22190681 DOI: 10.1074/jbc.m111.304899] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
A quantitative description of carrier-mediated nuclear export in live cells is presented. To this end, we fused a prototypical leucine-rich nuclear export signal (NES) to GFP as a cargo model and expressed the fluorescent chimera in live CHO-K1 cells. By modeling FRAP data, we calculate the NES affinity for the export machinery and the maximum rate of nuclear export achievable at saturation of endogenous carriers. The measured active-export time through the Nuclear Pore Complex (NPC) is 18 ms, remarkably similar to the previously determined active-import rate. Also, our results reveal that active export/import and active export/passive diffusion fluxes are uncoupled, thus complementing previous reports on active import/passive diffusion uncoupling. These findings suggest differential gating at the NPC level.
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Affiliation(s)
- Francesco Cardarelli
- Center for Nanotechnology Innovation @ NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12-56127 Pisa, Italy
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24
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Zonin E, Moscatiello R, Miuzzo M, Cavallarin N, Di Paolo ML, Sandonà D, Marin O, Brini M, Negro A, Navazio L. TAT-mediated aequorin transduction: an alternative approach for effective calcium measurements in plant cells. PLANT & CELL PHYSIOLOGY 2011; 52:2225-35. [PMID: 22025557 DOI: 10.1093/pcp/pcr145] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Cell-penetrating peptides are short cationic peptides with the property of translocating across the plasma membrane and transferring macromolecules otherwise unable to permeate cell membranes. We investigated the potential ability of the protein transduction domain derived from amino acids 47-57 of the human immunodeficiency virus type 1 (HIV-1) TAT (transactivator of transcription) protein to be used as a nanocarrier for the delivery of aequorin, a Ca(2+)-sensitive photoprotein widely used as a reliable Ca(2+) reporter in cell populations. The TAT peptide, either covalently linked to apoaequorin or ionically bound to plasmids encoding differentially targeted aequorin, was supplied to plant suspension-cultured cells. The TAT-aequorin fusion protein was found to be rapidly and effectively translocated into plant cells. The chimeric molecule was internalized in fully active biological form and at levels suitable to monitor intracellular Ca(2+) concentrations. Plant cells incubated for just 5 min with TAT-aequorin responded to different environmental stimuli with the expected Ca(2+) signatures. On the other hand, TAT-mediated plasmid internalization did not provide the necessary level of transformation efficiency to allow calibration of luminescence signals into Ca(2+) concentration values. These results indicate that TAT-mediated aequorin transduction is a promising alternative to traditional plant transformation methods to monitor intracellular Ca(2+) dynamics rapidly and effectively in plant cells.
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Affiliation(s)
- Elisabetta Zonin
- Dipartimento di Biologia, Università di Padova, Via U. Bassi 58/B, 35131 Padova, Italy
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Debaisieux S, Rayne F, Yezid H, Beaumelle B. The ins and outs of HIV-1 Tat. Traffic 2011; 13:355-63. [PMID: 21951552 DOI: 10.1111/j.1600-0854.2011.01286.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 09/19/2011] [Accepted: 09/19/2011] [Indexed: 12/18/2022]
Abstract
HIV-1 encodes for the small basic protein Tat (86-101 residues) that drastically enhances the efficiency of viral transcription. The mechanism enabling Tat nuclear import is not yet clear, but studies using reporter proteins fused to the Tat basic domain indicate that Tat could reach the nucleus by passive diffusion. Tat also uses an unusual transcellular transport pathway. The first step of this pathway involves high-affinity binding of Tat to phosphatidylinositol (4,5) bisphosphate (PI(4,5)P(2)), a phospholipid that is concentrated in the inner leaflet of the plasma membrane and enables Tat recruitment at this level. Tat then crosses the plasma membrane to reach the outside medium. Although unconventional, Tat secretion by infected cells is highly active, and export is the major destination for HIV-1 Tat. Secreted Tat can bind to a variety of cell types using several different receptors. Most of them will allow Tat endocytosis. Upon internalization, low endosomal pH triggers a conformational change in Tat that results in membrane insertion. Later steps of Tat translocation to the target-cell cytosol are assisted by Hsp90, a general cytosolic chaperone. Cytosolic Tat can trigger various cell responses. Indeed, accumulating evidence suggests that extracellular Tat acts as a viral toxin that affects the biological activity of different cell types and has a key role in acquired immune-deficiency syndrome development. This review focuses on some of the recently identified molecular details underlying the unusual transcellular transport pathway used by Tat, such as the role of the single Trp in Tat for its membrane insertion and translocation.
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Affiliation(s)
- Solène Debaisieux
- CPBS, UMR 5236 CNRS, Université de Montpellier, 1919 Route de Mende, 34923, Montpellier Cedex 05, France
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26
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Sarmady M, Dampier W, Tozeren A. HIV protein sequence hotspots for crosstalk with host hub proteins. PLoS One 2011; 6:e23293. [PMID: 21858059 PMCID: PMC3156123 DOI: 10.1371/journal.pone.0023293] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/12/2011] [Indexed: 11/18/2022] Open
Abstract
HIV proteins target host hub proteins for transient binding interactions. The presence of viral proteins in the infected cell results in out-competition of host proteins in their interaction with hub proteins, drastically affecting cell physiology. Functional genomics and interactome datasets can be used to quantify the sequence hotspots on the HIV proteome mediating interactions with host hub proteins. In this study, we used the HIV and human interactome databases to identify HIV targeted host hub proteins and their host binding partners (H2). We developed a high throughput computational procedure utilizing motif discovery algorithms on sets of protein sequences, including sequences of HIV and H2 proteins. We identified as HIV sequence hotspots those linear motifs that are highly conserved on HIV sequences and at the same time have a statistically enriched presence on the sequences of H2 proteins. The HIV protein motifs discovered in this study are expressed by subsets of H2 host proteins potentially outcompeted by HIV proteins. A large subset of these motifs is involved in cleavage, nuclear localization, phosphorylation, and transcription factor binding events. Many such motifs are clustered on an HIV sequence in the form of hotspots. The sequential positions of these hotspots are consistent with the curated literature on phenotype altering residue mutations, as well as with existing binding site data. The hotspot map produced in this study is the first global portrayal of HIV motifs involved in altering the host protein network at highly connected hub nodes.
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MESH Headings
- Amino Acid Motifs/genetics
- Amino Acid Sequence
- Binding Sites/genetics
- CREB-Binding Protein/metabolism
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Calmodulin/metabolism
- Casein Kinase II/metabolism
- Databases, Protein
- Human Immunodeficiency Virus Proteins/chemistry
- Human Immunodeficiency Virus Proteins/genetics
- Human Immunodeficiency Virus Proteins/metabolism
- Humans
- Hydrophobic and Hydrophilic Interactions
- Mitogen-Activated Protein Kinase 1/metabolism
- Models, Molecular
- Protein Binding
- Protein Interaction Mapping/methods
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Proteins/genetics
- Proteins/metabolism
- env Gene Products, Human Immunodeficiency Virus/chemistry
- env Gene Products, Human Immunodeficiency Virus/genetics
- env Gene Products, Human Immunodeficiency Virus/metabolism
- gag Gene Products, Human Immunodeficiency Virus/chemistry
- gag Gene Products, Human Immunodeficiency Virus/genetics
- gag Gene Products, Human Immunodeficiency Virus/metabolism
- nef Gene Products, Human Immunodeficiency Virus/chemistry
- nef Gene Products, Human Immunodeficiency Virus/genetics
- nef Gene Products, Human Immunodeficiency Virus/metabolism
- rev Gene Products, Human Immunodeficiency Virus/chemistry
- rev Gene Products, Human Immunodeficiency Virus/genetics
- rev Gene Products, Human Immunodeficiency Virus/metabolism
- tat Gene Products, Human Immunodeficiency Virus/chemistry
- tat Gene Products, Human Immunodeficiency Virus/genetics
- tat Gene Products, Human Immunodeficiency Virus/metabolism
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Affiliation(s)
- Mahdi Sarmady
- Center for Integrated Bioinformatics, Drexel University, Philadelphia, Pennsylvania, United States of America
| | - William Dampier
- Center for Integrated Bioinformatics, Drexel University, Philadelphia, Pennsylvania, United States of America
| | - Aydin Tozeren
- Center for Integrated Bioinformatics, Drexel University, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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27
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Hinde E, Cardarelli F. Measuring the flow of molecules in cells. Biophys Rev 2011; 3:119. [PMID: 28510061 DOI: 10.1007/s12551-011-0051-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 07/01/2011] [Indexed: 12/23/2022] Open
Abstract
No methods proposed thus far have the capability to measure molecular flow in live cells at the single molecule level. Here, we review the potentiality of a newly established method based on the spatial correlation of fluorescence fluctuations at a pair of points in the sample (pair correlation method). The pair correlation function (pCF) offers a unique tool to probe the directionality of intracellular traffic, by measuring the accessibility of the cellular landscape and its role in determining the diffusive routes adopted by molecules. The sensitivity of the pCF method toward detection of barriers means that different structural elements of the cell can be tested in terms of penetrability and mechanisms of regulation imparted on molecular flow. This has been recently demonstrated in a series of studies looking at molecular transport inside live cells. Here, we will review the theory behind detection of barriers to molecular flow, the rules to interpret pCF data, and relevant applications to intracellular transport.
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Affiliation(s)
- Elizabeth Hinde
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Francesco Cardarelli
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA. .,Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12, 56127, Pisa, Italy.
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28
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McQueen P, Donald LJ, Vo TN, Nguyen DH, Griffiths H, Shojania S, Standing KG, O'Neil JD. Tat peptide-calmodulin binding studies and bioinformatics of HIV-1 protein-calmodulin interactions. Proteins 2011; 79:2233-46. [DOI: 10.1002/prot.23048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 03/18/2011] [Accepted: 03/22/2011] [Indexed: 01/08/2023]
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Cardarelli F, Serresi M, Albanese A, Bizzarri R, Beltram F. Quantitative analysis of Tat peptide binding to import carriers reveals unconventional nuclear transport properties. J Biol Chem 2011; 286:12292-9. [PMID: 21321119 DOI: 10.1074/jbc.m110.203083] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A detailed study of nuclear import mediated by the HIV-1 Tat peptide (47YGRKKRRQRRR57, TatRRR) is reported. Fluorescence-based measurements, calibration of protein concentrations, and binding assays are exploited to address the physicochemical mechanisms of Tat peptide recognition by the classical importin α (Impα) and importin β (Impβ) receptors both in vitro and in intact cells. We show that TatRRR is an unconventional nuclear localization sequence that binds directly to both Impα and Impβ carriers in the absence of competitors (in vitro), whereas this property is silenced in the actual cellular environment. In the latter case, Impα/β-dependent nuclear import can be successfully restored by replacing the "RRR" stretch with "GGG". We apply a recently developed method to determine quantitatively TatGGG affinity for each receptor. Based on these results, we can rationalize previous controversial reports on the Tat peptide and provide coherent guidelines for the design of novel intracellular targeting sequences.
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Affiliation(s)
- Francesco Cardarelli
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di TecnologiaConsiglio Nazionale delle Ricerche, Scuola Normale Superiore, Pisa, Italy.
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Interference with Sin3 function induces epigenetic reprogramming and differentiation in breast cancer cells. Proc Natl Acad Sci U S A 2010; 107:11811-6. [PMID: 20547842 DOI: 10.1073/pnas.1006737107] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Sin3A/B is a master transcriptional scaffold and corepressor that plays an essential role in the regulation of gene transcription and maintenance of chromatin structure, and its inappropriate recruitment has been associated with aberrant gene silencing in cancer. Sin3A/B are highly related, large, multidomian proteins that interact with a wide variety of transcription factors and corepressor components, and we examined whether disruption of the function of a specific domain could lead to epigenetic reprogramming and derepression of specific subsets of genes. To this end, we selected the Sin3A/B-paired amphipathic alpha-helices (PAH2) domain based on its established role in mediating the effects of a relatively small number of transcription factors containing a PAH2-binding motif known as the Sin3 interaction domain (SID). Here, we show that in both human and mouse breast cancer cells, the targeted disruption of Sin3 function by introduction of a SID decoy that interferes with PAH2 binding to SID-containing partner proteins reverted the silencing of genes involved in cell growth and differentiation. In particular, the SID decoy led to epigenetic reprogramming and reexpression of the important breast cancer-associated silenced genes encoding E-cadherin, estrogen receptor alpha, and retinoic acid receptor beta and impaired tumor growth in vivo. Interestingly, the SID decoy was effective in the triple-negative M.D. Anderson-Metastatic Breast-231 (MDA-MB-231) breast cancer cell line, restoring sensitivity to 17beta-estradiol, tamoxifen, and retinoids. Therefore, the development of small molecules that can block interactions between PAH2 and SID-containing proteins offers a targeted epigenetic approach for treating this type of breast cancer that may also have wider therapeutic implications.
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Cardarelli F, Gratton E. In vivo imaging of single-molecule translocation through nuclear pore complexes by pair correlation functions. PLoS One 2010; 5:e10475. [PMID: 20454622 PMCID: PMC2862743 DOI: 10.1371/journal.pone.0010475] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 04/11/2010] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Nuclear pore complexes (NPCs) mediate bidirectional transport of proteins, RNAs, and ribonucleoproteins across the double-membrane nuclear envelope. Although there are many studies that look at the traffic in the nucleus and through the nuclear envelope we propose a method to detect the nucleocytoplasmic transport kinetics in an unperturbed cell, with no requirement for specific labeling of isolated molecules and, most important, in the presence of the cell milieu. METHODOLOGY The pair correlation function method (pCF) measures the time a molecule takes to migrate from one location to another within the cell in the presence of many molecules of the same kind. The spatial and temporal correlation among two arbitrary points in the cell provides a local map of molecular transport, and also highlights the presence of barriers to diffusion with millisecond time resolution and spatial resolution limited by diffraction. We use the pair correlation method to monitor a model protein substrate undergoing transport through NPCs in living cells, a biological problem in which single particle tracking (SPT) has given results that cannot be confirmed by traditional single-point FCS measurements because of the lack of spatial resolution. CONCLUSIONS We show that obstacles to molecular flow can be detected and that the pCF algorithm can recognize the heterogeneity of protein intra-compartment diffusion as well as the presence of barriers to transport across NE.
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Affiliation(s)
- Francesco Cardarelli
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, California, United States of America
- * E-mail:
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Albertazzi L, Serresi M, Albanese A, Beltram F. Dendrimer Internalization and Intracellular Trafficking in Living Cells. Mol Pharm 2010; 7:680-8. [DOI: 10.1021/mp9002464] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Lorenzo Albertazzi
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, I-56127 Pisa, Italy, and IIT@NEST, Center for Nanotechnology Innovation, I-56127 Pisa, Italy
| | - Michela Serresi
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, I-56127 Pisa, Italy, and IIT@NEST, Center for Nanotechnology Innovation, I-56127 Pisa, Italy
| | - Alberto Albanese
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, I-56127 Pisa, Italy, and IIT@NEST, Center for Nanotechnology Innovation, I-56127 Pisa, Italy
| | - Fabio Beltram
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, I-56127 Pisa, Italy, and IIT@NEST, Center for Nanotechnology Innovation, I-56127 Pisa, Italy
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Cardarelli F, Bizzarri R, Serresi M, Albertazzi L, Beltram F. Probing nuclear localization signal-importin alpha binding equilibria in living cells. J Biol Chem 2009; 284:36638-36646. [PMID: 19858191 DOI: 10.1074/jbc.m109.036699] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The regulated process of protein import into the nucleus of a eukaryotic cell is mediated by specific nuclear localization signals (NLSs) that are recognized by protein-import receptors. In this study, we present fluorescence-based methods to quantitatively address the physicochemical details of NLS recognition by the receptor protein importin alpha (Impalpha) in living cells. First, by combining fluorescence recovery after photobleaching measurements and protein-concentration calibration, we quantitatively define nuclear import saturability and afford an affinity value for NLS-Impalpha binding. Second, by fluorescence lifetime imaging microscopy, we directly monitor the occurrence of NLS-Impalpha interaction and measure its effective dissociation constant (K(D)) in the actual cellular environment. Our kinetic and thermodynamic analyses independently indicate that the subsaturation of Impalpha with the expressed NLS cargo regulates nuclear import rates in living cells, in contrast to what can be predicted on the basis of available in vitro data. Finally, our experiments also provide evidence for the regulation of nuclear import mediated by the intrasteric importin beta-binding domain of Impalpha and yield the first estimate of its autoinhibition energy in living cells.
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Affiliation(s)
- Francesco Cardarelli
- National Enterprise for nanoScience and nanoTechnology, Scuola Normale Superiore, and Consiglio Nazionale delle Ricerche-Istituto Nazionale per la Fisica della Materia, Piazza S. Silvestro 12, 56126 Pisa, Italy.
| | - Ranieri Bizzarri
- National Enterprise for nanoScience and nanoTechnology, Scuola Normale Superiore, and Consiglio Nazionale delle Ricerche-Istituto Nazionale per la Fisica della Materia, Piazza S. Silvestro 12, 56126 Pisa, Italy; IIT@NEST, Center for Nanotechnology Innovation, Piazza S. Silvestro 12, 56126 Pisa, Italy
| | - Michela Serresi
- National Enterprise for nanoScience and nanoTechnology, Scuola Normale Superiore, and Consiglio Nazionale delle Ricerche-Istituto Nazionale per la Fisica della Materia, Piazza S. Silvestro 12, 56126 Pisa, Italy; IIT@NEST, Center for Nanotechnology Innovation, Piazza S. Silvestro 12, 56126 Pisa, Italy
| | - Lorenzo Albertazzi
- National Enterprise for nanoScience and nanoTechnology, Scuola Normale Superiore, and Consiglio Nazionale delle Ricerche-Istituto Nazionale per la Fisica della Materia, Piazza S. Silvestro 12, 56126 Pisa, Italy; IIT@NEST, Center for Nanotechnology Innovation, Piazza S. Silvestro 12, 56126 Pisa, Italy
| | - Fabio Beltram
- National Enterprise for nanoScience and nanoTechnology, Scuola Normale Superiore, and Consiglio Nazionale delle Ricerche-Istituto Nazionale per la Fisica della Materia, Piazza S. Silvestro 12, 56126 Pisa, Italy; IIT@NEST, Center for Nanotechnology Innovation, Piazza S. Silvestro 12, 56126 Pisa, Italy
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Higashiyama Y, Takahashi A, Fukumoto Y, Nakayama Y, Yamaguchi N. Induction of chromatin condensation by nuclear expression of a novel arginine-rich cationic protein genetically engineered from the enhanced green fluorescent protein. Cytotechnology 2009; 60:153-9. [PMID: 19763862 DOI: 10.1007/s10616-009-9227-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 08/30/2009] [Indexed: 10/20/2022] Open
Abstract
In the interphase nuclei of cultured cells, chromatin is compacted and organized in higher-order structures through the condensation and decondensation processes. Chromosomes in the interphase nucleus are known to occupy distinct territories. The chromosome territory-interchromatin compartment model premises that the interchromatin compartment is separated from compact higher-order chromatin domains and expands in between these chromatin-organized territories. Chromatin in cultured cells is compacted under some conditions, such as the stress of heat shock and high osmolarity, and Src-mediated nuclear tyrosine phosphorylation. We report here that a novel arginine-rich cationic protein is generated by frameshift mutation of enhanced green fluorescent protein (EGFP). The arginine-rich cationic protein is highly hydrophilic and contains potential arginine-based nuclear localization signals. Expression of the arginine-rich cationic protein shows its predominant localization to the nucleus and induces striking chromatin condensation in the interphase, which might be involved in interchromatin spacing or euchromatinization. Thus, the arginine-rich cationic protein as a new tool would be useful for dissecting chromatin architecture dynamics.
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Affiliation(s)
- Yukihiro Higashiyama
- Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, 260-8675, Japan
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Moore NM, Sheppard CL, Sakiyama-Elbert SE. Characterization of a multifunctional PEG-based gene delivery system containing nuclear localization signals and endosomal escape peptides. Acta Biomater 2009; 5:854-64. [PMID: 18926782 DOI: 10.1016/j.actbio.2008.09.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 08/25/2008] [Accepted: 09/23/2008] [Indexed: 11/27/2022]
Abstract
Endosomal escape and nuclear localization are two barriers to gene delivery that need to be addressed in the design of new nonviral gene delivery vehicles. We have previously synthesized low-toxicity polyethylene glycol (PEG)-based vehicles with endosomal escape functionalities, but it was determined that the transfection efficiency of PEG-based vehicles that escaped the endosome was still limited by poor nuclear localization. Two different nuclear localization signal (NLS) peptides, SV40 and TAT, were coupled to PEG-based vehicles with DNA-binding peptides (DBPs) to determine the effect of NLS peptides on the transfection efficiency of PEG-based gene delivery vehicles. Coupling one SV40 peptide, a classical NLS, or two TAT peptides, a nonclassical NLS, to PEG-DBP vehicles increased the transfection efficiency of PEG-DBP/DNA particles 15-fold and resulted in similar efficiency to that of a common cationic polymer vehicle, polyethylenimine (PEI). The transfection efficiency of both types of PEG-DBP-NLS particles was further increased 7-fold in the presence of chloroquine, suggesting that the transfection efficiency of PEG-DBP-NLS particles is limited by their ability to escape the endosome. To develop particles that could escape the endosome and target the nucleus, a mixture of PEG-DBP-NLS vehicles and PEG-based vehicles with DBPs and endosomal escape peptides were complexed with plasmid DNA to form multifunctional particles that had a transfection efficiency 2-3 times higher than that of PEI. Additionally, the PEG-based vehicles were less toxic and more resistant to nonspecific protein adsorption than PEI, making them an attractive alternative for nonviral gene delivery.
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Affiliation(s)
- Nicole M Moore
- Department of Environmental, Energy, and Chemical Engineering, Washington University, One Brookings Drive, Saint Louis, MO 63130-4899, USA
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Serresi M, Bizzarri R, Cardarelli F, Beltram F. Real-time measurement of endosomal acidification by a novel genetically encoded biosensor. Anal Bioanal Chem 2008; 393:1123-33. [PMID: 19034435 DOI: 10.1007/s00216-008-2489-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 10/13/2008] [Accepted: 10/16/2008] [Indexed: 10/21/2022]
Abstract
Genetically encoded fluorescent proteins are optimal reporters when used to monitor cellular processes as they can be targeted to any subcellular region by fusion to a protein of interest. Here, we present the pH-sensitive fluorescent protein E(1)GFP which is ideally suited to monitor pH changes in dynamic intracellular structures in real time with high spatio temporal resolution. E(1)GFP is a ratiometric pH indicator by emission with a pK close to 6.0. We describe an application of this novel pH reporter in the measurement of pH changes along the endo-lysosomal pathway. By fusing E(1)GFP to the HIV-Tat protein which is endowed with cell-penetrating properties, we were able to monitor multi-step endocytosis from the initial cell-surface binding through to the intracellular endocytic network in real time. This represents a framework for the application of E(1)GFP to the in situ detection of pH changes involved in dynamic biological phenomena.
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Affiliation(s)
- Michela Serresi
- NEST, Scuola Normale Superiore and Italian Institute of Technology, Piazza San Silvestro 12, 56124, Pisa, Italy.
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Green fluorescent protein based pH indicators for in vivo use: a review. Anal Bioanal Chem 2008; 393:1107-22. [DOI: 10.1007/s00216-008-2515-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2008] [Revised: 11/03/2008] [Accepted: 11/05/2008] [Indexed: 10/21/2022]
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