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Pan W, Deng L, Wang H, Wang VYF. Atypical IκB Bcl3 enhances the generation of the NF-κB p52 homodimer. Front Cell Dev Biol 2022; 10:930619. [PMID: 35990614 PMCID: PMC9389042 DOI: 10.3389/fcell.2022.930619] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/01/2022] [Indexed: 11/25/2022] Open
Abstract
The NF-κB family of dimeric transcription factors regulate diverse biological functions. Their cellular expression profiles differ, which lead to different concentrations in different cell/tissue types. Although the activation mechanisms of different NF-κB dimers have been widely investigated, there is limited information on specific NF-κB dimers’ formation. The NF-κB p52:p52 homodimer regulates an important subset of target genes in cancer cells; however, the molecular mechanism of the generation of this specific homodimer remains unclear. Our study has revealed that the atypical IκB protein, Bcl3, plays an essential role in enhancing the p52:p52 homodimer population which is a unique mechanism to p52 within the NF-κB family. p52 was shown to heterodimerize with four other NF-κB subunits (RelA, RelB, cRel, and p50); all heterodimers, except p52:p50, are significantly more stable than the p52:p52 homodimer. Bcl3 is able to compete with all other NF-κB subunits in cells for efficient p52:p52 homodimer formation which consequently leads to the upregulation of target genes that are involved in cell proliferation, migration, and inflammation, which explain why aberrant activation of Bcl3 and p52 leads to cancer.
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Affiliation(s)
- Wenfei Pan
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Macau SAR, China
| | - Limei Deng
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Macau SAR, China
| | - Haitao Wang
- Thoracic Surgery Branch, Clinical Research, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, MD, United States
| | - Vivien Ya-Fan Wang
- Faculty of Health Sciences, University of Macau, Avenida da Universidade, Macau SAR, China
- Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida da Universidade, Macau SAR, China
- MoE Frontiers Science Center for Precision Oncology, University of Macau, Avenida da Universidade, Macau SAR, China
- *Correspondence: Vivien Ya-Fan Wang,
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2
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Hsu TY, Zhang B, L'Etoile ND, Juang BT. C. elegans orthologs MUT-7/CeWRN-1 of Werner syndrome protein regulate neuronal plasticity. eLife 2021; 10:62449. [PMID: 33646120 PMCID: PMC7946423 DOI: 10.7554/elife.62449] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 02/26/2021] [Indexed: 12/28/2022] Open
Abstract
Caenorhabditis elegans expresses human Werner syndrome protein (WRN) orthologs as two distinct proteins: MUT-7, with a 3′−5′ exonuclease domain, and CeWRN-1, with helicase domains. How these domains cooperate remains unclear. Here, we demonstrate the different contributions of MUT-7 and CeWRN-1 to 22G small interfering RNA (siRNA) synthesis and the plasticity of neuronal signaling. MUT-7 acts specifically in the cytoplasm to promote siRNA biogenesis and in the nucleus to associate with CeWRN-1. The import of siRNA by the nuclear Argonaute NRDE-3 promotes the loading of the heterochromatin-binding protein HP1 homolog HPL-2 onto specific loci. This heterochromatin complex represses the gene expression of the guanylyl cyclase ODR-1 to direct olfactory plasticity in C. elegans. Our findings suggest that the exonuclease and helicase domains of human WRN may act in concert to promote RNA-dependent loading into a heterochromatin complex, and the failure of this entire process reduces plasticity in postmitotic neurons.
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Affiliation(s)
- Tsung-Yuan Hsu
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, United States
| | - Bo Zhang
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, United States
| | - Noelle D L'Etoile
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, United States
| | - Bi-Tzen Juang
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
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Jia Y, Bleicher F, Reboulet J, Merabet S. Bimolecular Fluorescence Complementation (BiFC) and Multiplexed Imaging of Protein-Protein Interactions in Human Living Cells. Methods Mol Biol 2021; 2350:173-190. [PMID: 34331286 DOI: 10.1007/978-1-0716-1593-5_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Deciphering protein-protein interactions (PPIs) in vivo is crucial to understand protein function. Bimolecular fluorescence complementation (BiFC) makes applicable the analysis of PPIs in many different native contexts, including human live cells. It relies on the property of monomeric fluorescent proteins to be reconstituted from two separate subfragments upon spatial proximity. Candidate partners fused to such complementary subfragments can form a fluorescent protein complex upon interaction, allowing visualization of weak and transient PPIs. It can also be applied for investigation of distinct PPIs at the same time using a multicolor setup. In this chapter, we provide a detailed protocol for analyzing PPIs by doing BiFC in cultured cells. Proof-of-principle experiments rely on the complementation property between the N-terminal fragment of mVenus (designated VN173) and the C-terminal fragment of mCerulean (designated CC155) and the partnership between HOXA7 and PBX1 proteins. This protocol is compatible with any other fluorescent complementation pair fragments and any type of candidate interacting proteins.
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Affiliation(s)
- Yunlong Jia
- Institut de Génomique Fonctionnelle de Lyon, UMR5242, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, Lyon Cedex 07, France
| | - Françoise Bleicher
- Institut de Génomique Fonctionnelle de Lyon, UMR5242, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, Lyon Cedex 07, France
| | - Jonathan Reboulet
- Institut de Génomique Fonctionnelle de Lyon, UMR5242, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, Lyon Cedex 07, France
| | - Samir Merabet
- Institut de Génomique Fonctionnelle de Lyon, UMR5242, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, Lyon Cedex 07, France.
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Immarigeon C, Bernat-Fabre S, Guillou E, Verger A, Prince E, Benmedjahed MA, Payet A, Couralet M, Monte D, Villeret V, Bourbon HM, Boube M. Mediator complex subunit Med19 binds directly GATA transcription factors and is required with Med1 for GATA-driven gene regulation in vivo. J Biol Chem 2020; 295:13617-13629. [PMID: 32737196 DOI: 10.1074/jbc.ra120.013728] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 07/21/2020] [Indexed: 02/02/2023] Open
Abstract
The evolutionarily conserved multiprotein Mediator complex (MED) serves as an interface between DNA-bound transcription factors (TFs) and the RNA Pol II machinery. It has been proposed that each TF interacts with a dedicated MED subunit to induce specific transcriptional responses. But are these binary partnerships sufficient to mediate TF functions? We have previously established that the Med1 Mediator subunit serves as a cofactor of GATA TFs in Drosophila, as shown in mammals. Here, we observe mutant phenotype similarities between another subunit, Med19, and the Drosophila GATA TF Pannier (Pnr), suggesting functional interaction. We further show that Med19 physically interacts with the Drosophila GATA TFs, Pnr and Serpent (Srp), in vivo and in vitro through their conserved C-zinc finger domains. Moreover, Med19 loss of function experiments in vivo or in cellulo indicate that it is required for Pnr- and Srp-dependent gene expression, suggesting general GATA cofactor functions. Interestingly, Med19 but not Med1 is critical for the regulation of all tested GATA target genes, implying shared or differential use of MED subunits by GATAs depending on the target gene. Lastly, we show a direct interaction between Med19 and Med1 by GST pulldown experiments indicating privileged contacts between these two subunits of the MED middle module. Together, these findings identify Med19/Med1 as a composite GATA TF interface and suggest that binary MED subunit-TF partnerships are probably oversimplified models. We propose several mechanisms to account for the transcriptional regulation of GATA-targeted genes.
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Affiliation(s)
- Clément Immarigeon
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France
| | - Sandra Bernat-Fabre
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France
| | - Emmanuelle Guillou
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France
| | - Alexis Verger
- Inserm, CHU Lille, Institut Pasteur de Lille, CNRS ERL 9002 Integrative Structural Biology, Université Lille, Lille, France
| | - Elodie Prince
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France
| | - Mohamed A Benmedjahed
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France
| | - Adeline Payet
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France
| | - Marie Couralet
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France
| | - Didier Monte
- Inserm, CHU Lille, Institut Pasteur de Lille, CNRS ERL 9002 Integrative Structural Biology, Université Lille, Lille, France
| | - Vincent Villeret
- Inserm, CHU Lille, Institut Pasteur de Lille, CNRS ERL 9002 Integrative Structural Biology, Université Lille, Lille, France
| | - Henri-Marc Bourbon
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France
| | - Muriel Boube
- Centre de Biologie Integrative CBD, UMR5547 CNRS/UPS, Université de Toulouse, Toulouse Cedex, France.
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Maldonado RJK, Rice B, Chen EC, Tuffy KM, Chiari EF, Fahrbach KM, Hope TJ, Parent LJ. Visualizing Association of the Retroviral Gag Protein with Unspliced Viral RNA in the Nucleus. mBio 2020; 11:e00524-20. [PMID: 32265329 PMCID: PMC7157774 DOI: 10.1128/mbio.00524-20] [Citation(s) in RCA: 8] [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: 03/07/2020] [Accepted: 03/12/2020] [Indexed: 11/20/2022] Open
Abstract
Packaging of genomic RNA (gRNA) by retroviruses is essential for infectivity, yet the subcellular site of the initial interaction between the Gag polyprotein and gRNA remains poorly defined. Because retroviral particles are released from the plasma membrane, it was previously thought that Gag proteins initially bound to gRNA in the cytoplasm or at the plasma membrane. However, the Gag protein of the avian retrovirus Rous sarcoma virus (RSV) undergoes active nuclear trafficking, which is required for efficient gRNA encapsidation (L. Z. Scheifele, R. A. Garbitt, J. D. Rhoads, and L. J. Parent, Proc Natl Acad Sci U S A 99:3944-3949, 2002, https://doi.org/10.1073/pnas.062652199; R. Garbitt-Hirst, S. P. Kenney, and L. J. Parent, J Virol 83:6790-6797, 2009, https://doi.org/10.1128/JVI.00101-09). These results raise the intriguing possibility that the primary contact between Gag and gRNA might occur in the nucleus. To examine this possibility, we created a RSV proviral construct that includes 24 tandem repeats of MS2 RNA stem-loops, making it possible to track RSV viral RNA (vRNA) in live cells in which a fluorophore-conjugated MS2 coat protein is coexpressed. Using confocal microscopy, we observed that both wild-type Gag and a nuclear export mutant (Gag.L219A) colocalized with vRNA in the nucleus. In live-cell time-lapse images, the wild-type Gag protein trafficked together with vRNA as a single ribonucleoprotein (RNP) complex in the nucleoplasm near the nuclear periphery, appearing to traverse the nuclear envelope into the cytoplasm. Furthermore, biophysical imaging methods suggest that Gag and the unspliced vRNA physically interact in the nucleus. Taken together, these data suggest that RSV Gag binds unspliced vRNA to export it from the nucleus, possibly for packaging into virions as the viral genome.IMPORTANCE Retroviruses cause severe diseases in animals and humans, including cancer and acquired immunodeficiency syndromes. To propagate infection, retroviruses assemble new virus particles that contain viral proteins and unspliced vRNA to use as gRNA. Despite the critical requirement for gRNA packaging, the molecular mechanisms governing the identification and selection of gRNA by the Gag protein remain poorly understood. In this report, we demonstrate that the Rous sarcoma virus (RSV) Gag protein colocalizes with unspliced vRNA in the nucleus in the interchromatin space. Using live-cell confocal imaging, RSV Gag and unspliced vRNA were observed to move together from inside the nucleus across the nuclear envelope, suggesting that the Gag-gRNA complex initially forms in the nucleus and undergoes nuclear export into the cytoplasm as a viral ribonucleoprotein (vRNP) complex.
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Affiliation(s)
| | - Breanna Rice
- Department of Medicine, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Eunice C Chen
- Department of Medicine, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Kevin M Tuffy
- Department of Medicine, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Estelle F Chiari
- Department of Medicine, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Kelly M Fahrbach
- Department of Cell and Molecular Biology, Northwestern University, Chicago, Illinois, USA
| | - Thomas J Hope
- Department of Cell and Molecular Biology, Northwestern University, Chicago, Illinois, USA
| | - Leslie J Parent
- Department of Medicine, Penn State College of Medicine, Hershey, Pennsylvania, USA
- Department of Microbiology and Immunology, Penn State College of Medicine, Hershey, Pennsylvania, USA
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6
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Nan H, Lan J, Tian M, Dong S, Tian J, Liu L, Xu X, Chen H. The Network of Interactions Among Porcine Reproductive and Respiratory Syndrome Virus Non-structural Proteins. Front Microbiol 2018; 9:970. [PMID: 29867873 PMCID: PMC5960727 DOI: 10.3389/fmicb.2018.00970] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 04/25/2018] [Indexed: 12/22/2022] Open
Abstract
The RNA synthesis of porcine reproductive and respiratory syndrome virus (PRRSV), a positive-strand RNA virus, is compartmentalized in virus-induced double-membrane vesicles where viral proteins and some cellular proteins assemble into replication and transcription complexes (RTCs). The viral replicase proteins are the major components of the RTCs but the physical associations among these non-structural proteins (nsps) remain elusive. In this study, we investigated the potential interactions between PRRSV nsps by yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BiFC) and pull-down assays. Our analyses revealed a complex network of interactions involving most of PRRSV nsps. Among them, nsp9 and nsp12 were identified as the hubs of the nsp interactome; transmembrane proteins nsp2 and nsp5 both interacted with nsp3, indicating that the three membrane-bound proteins might bind together to form the scaffold to support the association of RTCs with the intracellular membrane. The PRRSV nsp interactions identified in this study may provide valuable clues for future researches on the RTC formation and function.
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Affiliation(s)
- Hao Nan
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Jixun Lan
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Mengmeng Tian
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Shan Dong
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Jiao Tian
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Long Liu
- College of Life Sciences, Northwest A&F University, Yangling, China.,School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, China
| | - Xiaodong Xu
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Hongying Chen
- College of Life Sciences, Northwest A&F University, Yangling, China.,Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, China
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7
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Guan X, Chen S, Voon CP, Wong KB, Tikkanen M, Lim BL. FdC1 and Leaf-Type Ferredoxins Channel Electrons From Photosystem I to Different Downstream Electron Acceptors. FRONTIERS IN PLANT SCIENCE 2018; 9:410. [PMID: 29670639 PMCID: PMC5893904 DOI: 10.3389/fpls.2018.00410] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 03/14/2018] [Indexed: 05/24/2023]
Abstract
Plant-type ferredoxins in Arabidopsis transfer electrons from the photosystem I to multiple redox-driven enzymes involved in the assimilation of carbon, nitrogen, and sulfur. Leaf-type ferredoxins also modulate the switch between the linear and cyclic electron routes of the photosystems. Recently, two novel ferredoxin homologs with extra C-termini were identified in the Arabidopsis genome (AtFdC1, AT4G14890; AtFdC2, AT1G32550). FdC1 was considered as an alternative electron acceptor of PSI under extreme ferredoxin-deficient conditions. Here, we showed that FdC1 could interact with some, but not all, electron acceptors of leaf-type Fds, including the ferredoxin-thioredoxin reductase (FTR), sulfite reductase (SiR), and nitrite reductase (NiR). Photoreduction assay on cytochrome c and enzyme assays confirmed its capability to receive electrons from PSI and donate electrons to the Fd-dependent SiR and NiR but not to the ferredoxin-NADP+ oxidoreductase (FNR). Hence, FdC1 and leaf-type Fds may play differential roles by channeling electrons from photosystem I to different downstream electron acceptors in photosynthetic tissues. In addition, the median redox potential of FdC1 may allow it to receive electrons from FNR in non-photosynthetic plastids.
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Affiliation(s)
- Xiaoqian Guan
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Shuai Chen
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Chia Pao Voon
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kam-Bo Wong
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Mikko Tikkanen
- Department of Biochemistry and Food Chemistry, Molecular Plant Biology, University of Turku, Turku, Finland
| | - Boon L. Lim
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
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8
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Donlin-Asp PG, Fallini C, Campos J, Chou CC, Merritt ME, Phan HC, Bassell GJ, Rossoll W. The Survival of Motor Neuron Protein Acts as a Molecular Chaperone for mRNP Assembly. Cell Rep 2017; 18:1660-1673. [PMID: 28199839 DOI: 10.1016/j.celrep.2017.01.059] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/16/2016] [Accepted: 01/24/2017] [Indexed: 12/23/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a motor neuron disease caused by reduced levels of the survival of motor neuron (SMN) protein. SMN is part of a multiprotein complex that facilitates the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). SMN has also been found to associate with mRNA-binding proteins, but the nature of this association was unknown. Here, we have employed a combination of biochemical and advanced imaging methods to demonstrate that SMN promotes the molecular interaction between IMP1 protein and the 3' UTR zipcode region of β-actin mRNA, leading to assembly of messenger ribonucleoprotein (mRNP) complexes that associate with the cytoskeleton to facilitate trafficking. We have identified defects in mRNP assembly in cells and tissues from SMA disease models and patients that depend on the SMN Tudor domain and explain the observed deficiency in mRNA localization and local translation, providing insight into SMA pathogenesis as a ribonucleoprotein (RNP)-assembly disorder.
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Affiliation(s)
- Paul G Donlin-Asp
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Claudia Fallini
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jazmin Campos
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ching-Chieh Chou
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Megan E Merritt
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Laboratory of Translational Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Han C Phan
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA; Laboratory of Translational Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Wilfried Rossoll
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA; Laboratory of Translational Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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9
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Weems A, McMurray M. The step-wise pathway of septin hetero-octamer assembly in budding yeast. eLife 2017; 6. [PMID: 28541184 PMCID: PMC5461111 DOI: 10.7554/elife.23689] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 05/24/2017] [Indexed: 01/22/2023] Open
Abstract
Septin proteins bind guanine nucleotides and form rod-shaped hetero-oligomers. Cells choose from a variety of available septins to assemble distinct hetero-oligomers, but the underlying mechanism was unknown. Using a new in vivo assay, we find that a stepwise assembly pathway produces the two species of budding yeast septin hetero-octamers: Cdc11/Shs1–Cdc12–Cdc3–Cdc10–Cdc10–Cdc3–Cdc12–Cdc11/Shs1. Rapid GTP hydrolysis by monomeric Cdc10 drives assembly of the core Cdc10 homodimer. The extended Cdc3 N terminus autoinhibits Cdc3 association with Cdc10 homodimers until prior Cdc3–Cdc12 interaction. Slow hydrolysis by monomeric Cdc12 and specific affinity of Cdc11 for transient Cdc12•GTP drive assembly of distinct trimers, Cdc11–Cdc12–Cdc3 or Shs1–Cdc12–Cdc3. Decreasing the cytosolic GTP:GDP ratio increases the incorporation of Shs1 vs Cdc11, which alters the curvature of filamentous septin rings. Our findings explain how GTP hydrolysis controls septin assembly, and uncover mechanisms by which cells construct defined septin complexes. DOI:http://dx.doi.org/10.7554/eLife.23689.001
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Affiliation(s)
- Andrew Weems
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Michael McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States
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10
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Screening for Novel Small-Molecule Inhibitors Targeting the Assembly of Influenza Virus Polymerase Complex by a Bimolecular Luminescence Complementation-Based Reporter System. J Virol 2017; 91:JVI.02282-16. [PMID: 28031371 DOI: 10.1128/jvi.02282-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 11/30/2016] [Indexed: 11/20/2022] Open
Abstract
Influenza virus RNA-dependent RNA polymerase consists of three viral protein subunits: PA, PB1, and PB2. Protein-protein interactions (PPIs) of these subunits play pivotal roles in assembling the functional polymerase complex, which is essential for the replication and transcription of influenza virus RNA. Here we developed a highly specific and robust bimolecular luminescence complementation (BiLC) reporter system to facilitate the investigation of influenza virus polymerase complex formation. Furthermore, by combining computational modeling and the BiLC reporter assay, we identified several novel small-molecule compounds that selectively inhibited PB1-PB2 interaction. Function of one such lead compound was confirmed by its activity in suppressing influenza virus replication. In addition, our studies also revealed that PA plays a critical role in enhancing interactions between PB1 and PB2, which could be important in targeting sites for anti-influenza intervention. Collectively, these findings not only aid the development of novel inhibitors targeting the formation of influenza virus polymerase complex but also present a new tool to investigate the exquisite mechanism of PPIs. IMPORTANCE Formation of the functional influenza virus polymerase involves complex protein-protein interactions (PPIs) of PA, PB1, and PB2 subunits. In this work, we developed a novel BiLC assay system which is sensitive and specific to quantify both strong and weak PPIs between influenza virus polymerase subunits. More importantly, by combining in silico modeling and our BiLC assay, we identified a small molecule that can suppress influenza virus replication by disrupting the polymerase assembly. Thus, we developed an innovative method to investigate PPIs of multisubunit complexes effectively and to identify new molecules inhibiting influenza virus polymerase assembly.
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11
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Lagarrigue F, Vikas Anekal P, Lee HS, Bachir AI, Ablack JN, Horwitz AF, Ginsberg MH. A RIAM/lamellipodin-talin-integrin complex forms the tip of sticky fingers that guide cell migration. Nat Commun 2015; 6:8492. [PMID: 26419705 PMCID: PMC4589889 DOI: 10.1038/ncomms9492] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/26/2015] [Indexed: 01/10/2023] Open
Abstract
The leading edge of migrating cells contains rapidly translocating activated integrins associated with growing actin filaments that form 'sticky fingers' to sense extracellular matrix and guide cell migration. Here we utilized indirect bimolecular fluorescence complementation to visualize a molecular complex containing a Mig-10/RIAM/lamellipodin (MRL) protein (Rap1-GTP-interacting adaptor molecule (RIAM) or lamellipodin), talin and activated integrins in living cells. This complex localizes at the tips of growing actin filaments in lamellipodial and filopodial protrusions, thus corresponding to the tips of the 'sticky fingers.' Formation of the complex requires talin to form a bridge between the MRL protein and the integrins. Moreover, disruption of the MRL protein-integrin-talin (MIT) complex markedly impairs cell protrusion. These data reveal the molecular basis of the formation of 'sticky fingers' at the leading edge of migrating cells and show that an MIT complex drives these protrusions.
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Affiliation(s)
- Frederic Lagarrigue
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Praju Vikas Anekal
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Ho-Sup Lee
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Alexia I Bachir
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Jailal N Ablack
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Alan F Horwitz
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Mark H Ginsberg
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
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12
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DeBonis S, Neumann E, Skoufias DA. Self protein-protein interactions are involved in TPPP/p25 mediated microtubule bundling. Sci Rep 2015; 5:13242. [PMID: 26289831 PMCID: PMC4542545 DOI: 10.1038/srep13242] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/15/2015] [Indexed: 12/26/2022] Open
Abstract
TPPP/p25 is a microtubule-associated protein, detected in protein inclusions associated with various neurodegenerative diseases. Deletion analysis data show that TPPP/p25 has two microtubule binding sites, both located in intrinsically disordered domains, one at the N-terminal and the other in the C-terminal domain. In copolymerization assays the full-length protein exhibits microtubule stimulation and bundling activity. In contrast, at the same ratio relative to tubulin, truncated forms of TPPP/p25 exhibit either lower or no microtubule stimulation and no bundling activity, suggesting a cooperative phenomenon which is enhanced by the presence of the two binding sites. The binding characteristics of the N- and C-terminally truncated proteins to taxol-stabilized microtubules are similar to the full-length protein. However, the C-terminally truncated TPPP/p25 shows a lower Bmax for microtubule binding, suggesting that it may bind to a site of tubulin that is masked in microtubules. Bimolecular fluorescent complementation assays in cells expressing combinations of various TPPP/p25 fragments, but not that of the central folded domain, resulted in the generation of a fluorescence signal colocalized with perinuclear microtubule bundles insensitive to microtubule inhibitors. The data suggest that the central folded domain of TPPP/p25 following binding to microtubules can drive s homotypic protein-protein interactions leading to bundled microtubules.
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Affiliation(s)
- Salvatore DeBonis
- Université de Grenoble Alpes, F-38044 Grenoble, France.,CNRS, F-38044 Grenoble, France.,CEA, IBS, F-38044 Grenoble, France
| | - Emmanuelle Neumann
- Université de Grenoble Alpes, F-38044 Grenoble, France.,CNRS, F-38044 Grenoble, France.,CEA, IBS, F-38044 Grenoble, France
| | - Dimitrios A Skoufias
- Université de Grenoble Alpes, F-38044 Grenoble, France.,CNRS, F-38044 Grenoble, France.,CEA, IBS, F-38044 Grenoble, France
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13
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Xu D, Zhan Y, Qi Y, Cao B, Bai S, Xu W, Gambhir SS, Lee P, Sartor O, Flemington EK, Zhang H, Hu CD, Dong Y. Androgen Receptor Splice Variants Dimerize to Transactivate Target Genes. Cancer Res 2015; 75:3663-71. [PMID: 26060018 DOI: 10.1158/0008-5472.can-15-0381] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 05/27/2015] [Indexed: 11/16/2022]
Abstract
Constitutively active androgen receptor splice variants (AR-V) lacking the ligand-binding domain have been implicated in the pathogenesis of castration-resistant prostate cancer and in mediating resistance to newer drugs that target the androgen axis. AR-V regulates expression of both canonical AR targets and a unique set of cancer-specific targets that are enriched for cell-cycle functions. However, little is known about how AR-V controls gene expression. Here, we report that two major AR-Vs, termed AR-V7 and AR(v567es), not only homodimerize and heterodimerize with each other but also heterodimerize with full-length androgen receptor (AR-FL) in an androgen-independent manner. We found that heterodimerization of AR-V and AR-FL was mediated by N- and C-terminal interactions and by the DNA-binding domain of each molecule, whereas AR-V homodimerization was mediated only by DNA-binding domain interactions. Notably, AR-V dimerization was required to transactivate target genes and to confer castration-resistant cell growth. Our results clarify the mechanism by which AR-Vs mediate gene regulation and provide a pivotal pathway for rational drug design to disrupt AR-V signaling as a rational strategy for the effective treatment of advanced prostate cancer.
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Affiliation(s)
- Duo Xu
- College of Life Sciences, Jilin University, Changchun, China. Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana. School of Nursing, Jilin University, Changchun, China
| | - Yang Zhan
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana
| | - Yanfeng Qi
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana
| | - Bo Cao
- College of Life Sciences, Jilin University, Changchun, China. Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana
| | - Shanshan Bai
- College of Life Sciences, Jilin University, Changchun, China. Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana
| | - Wei Xu
- McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, Wisconsin
| | - Sanjiv S Gambhir
- Bio-X Program and Department of Radiology, Stanford University School of Medicine, Stanford, California
| | - Peng Lee
- Department of Pathology, New York University School of Medicine, New York, New York
| | - Oliver Sartor
- Department of Urology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana. Department of Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana
| | - Erik K Flemington
- Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana
| | - Haitao Zhang
- Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana
| | - Chang-Deng Hu
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Yan Dong
- College of Life Sciences, Jilin University, Changchun, China. Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, Louisiana. National Engineering Laboratory for AIDS Vaccine, Jilin University, Changchun, China.
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14
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Fujinaga K, Luo Z, Schaufele F, Peterlin BM. Visualization of positive transcription elongation factor b (P-TEFb) activation in living cells. J Biol Chem 2014; 290:1829-36. [PMID: 25492871 DOI: 10.1074/jbc.m114.605816] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Regulation of transcription elongation by positive transcription elongation factor b (P-TEFb) plays a central role in determining the state of cell activation, proliferation, and differentiation. In cells, P-TEFb exists in active and inactive forms. Its release from the inactive 7SK small nuclear ribonucleoprotein complex is a critical step for P-TEFb to activate transcription elongation. However, no good method exists to analyze this P-TEFb equilibrium in living cells. Only inaccurate and labor-intensive cell-free biochemical assays are currently available. In this study, we present the first experimental system to monitor P-TEFb activation in living cells. We created a bimolecular fluorescence complementation assay to detect interactions between P-TEFb and its substrate, the C-terminal domain of RNA polymerase II. When cells were treated with suberoylanilide hydroxamic acid, which releases P-TEFb from the 7SK small nuclear ribonucleoprotein, they turned green. Other known P-TEFb-releasing agents, including histone deacetylase inhibitors, bromodomain and extraterminal bromodomain inhibitors, and protein kinase C agonists, also scored positive in this assay. Finally, we identified 5'-azacytidine as a new P-TEFb-releasing agent. This release of P-TEFb correlated directly with activation of human HIV and HEXIM1 transcription. Thus, our visualization of P-TEFb activation by fluorescent complementation assay could be used to find new P-TEFb-releasing agents, compare different classes of agents, and assess their efficacy singly and/or in combination.
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Affiliation(s)
- Koh Fujinaga
- From the Departments of Medicine, Microbiology, and Immunology and
| | - Zeping Luo
- From the Departments of Medicine, Microbiology, and Immunology and
| | - Fred Schaufele
- the Diabetes and Endocrinology Research Center, University of California, San Francisco, California 94143-0703
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15
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Martínez-Fábregas J, Díaz-Moreno I, González-Arzola K, Janocha S, Navarro JA, Hervás M, Bernhardt R, Velázquez-Campoy A, Díaz-Quintana A, De la Rosa MA. Structural and functional analysis of novel human cytochrome C targets in apoptosis. Mol Cell Proteomics 2014; 13:1439-56. [PMID: 24643968 DOI: 10.1074/mcp.m113.034322] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Since the first description of apoptosis four decades ago, great efforts have been made to elucidate, both in vivo and in vitro, the molecular mechanisms involved in its regulation. Although the role of cytochrome c during apoptosis is well established, relatively little is known about its participation in signaling pathways in vivo due to its essential role during respiration. To obtain a better understanding of the role of cytochrome c in the onset of apoptosis, we used a proteomic approach based on affinity chromatography with cytochrome c as bait in this study. In this approach, novel cytochrome c interaction partners were identified whose in vivo interaction and cellular localization were facilitated through bimolecular fluorescence complementation. Modeling of the complex interface between cytochrome c and its counterparts indicated the involvement of the surface surrounding the heme crevice of cytochrome c, in agreement with the vast majority of known redox adducts of cytochrome c. However, in contrast to the high turnover rate of the mitochondrial cytochrome c redox adducts, those occurring under apoptosis led to the formation of stable nucleo-cytoplasmic ensembles, as inferred mainly from surface plasmon resonance and nuclear magnetic resonance measurements, which permitted us to corroborate the formation of such complexes in vitro. The results obtained suggest that human cytochrome c interacts with pro-survival, anti-apoptotic proteins following its release into the cytoplasm. Thus, cytochrome c may interfere with cell survival pathways and unlock apoptosis in order to prevent the spatial and temporal coexistence of antagonist signals.
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Affiliation(s)
- Jonathan Martínez-Fábregas
- From the ‡Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Irene Díaz-Moreno
- From the ‡Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Katiuska González-Arzola
- From the ‡Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Simon Janocha
- §Institut für Biochemie, Universität des Saarlandes, Campus B2.2, D-66123 Saarbrücken, Germany
| | - José A Navarro
- From the ‡Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Manuel Hervás
- From the ‡Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Rita Bernhardt
- §Institut für Biochemie, Universität des Saarlandes, Campus B2.2, D-66123 Saarbrücken, Germany
| | - Adrián Velázquez-Campoy
- ¶Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint-Unit IQFR-CSIC-BIFI, Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain, and Fundacion ARAID, Government of Aragon, Zaragoza, Spain
| | - Antonio Díaz-Quintana
- From the ‡Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Miguel A De la Rosa
- From the ‡Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain;
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16
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Combined effect of Cameo2 and CBP on the cellular uptake of lutein in the silkworm, Bombyx mori. PLoS One 2014; 9:e86594. [PMID: 24475153 PMCID: PMC3903547 DOI: 10.1371/journal.pone.0086594] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 12/13/2013] [Indexed: 01/10/2023] Open
Abstract
Formation of yellow-red color cocoons in the silkworm, Bombyx mori, occurs as the result of the selective delivery of carotenoids from the midgut to the silk gland via the hemolymph. This process of pigment transport is thought to be mediated by specific cellular carotenoids carrier proteins. Previous studies indicated that two proteins, Cameo2 and CBP, are associated with the selective transport of lutein from the midgut into the silk gland in Bombyx mori. However, the exact roles of Cameo2 and CBP during the uptake and transport of carotenoids are still unknown. In this study, we investigated the respective contributions of these two proteins to lutein and β-carotene transport in Bombyx mori as well as commercial cell-line. We found that tissues, expressed both Cameo2 and CBP, accumulate lutein. Cells, co-expressed Cameo2 and CBP, absorb 2 fold more lutein (P<0.01) than any other transfected cells, and the rate of cellular uptake of lutein was concentration-dependent and reached saturation. From immunofluorescence staining, confocal microscopy observation and western blot analysis, Cameo2 was localized at the membrane and CBP was expressed in the cytosol. What’s more, bimolecular fluorescence complementation analysis showed that these two proteins directly interacted at cellular level. Therefore, Cameo2 and CBP are necessarily expressed in midguts and silk glands for lutein uptake in Bombyx mori. Cameo2 and CBP, as the membrane protein and the cytosol protein, respectively, have the combined effect to facilitate the cellular uptake of lutein.
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17
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Yu L, Takeda K, Markoff L. Protein-protein interactions among West Nile non-structural proteins and transmembrane complex formation in mammalian cells. Virology 2013; 446:365-77. [PMID: 24074601 DOI: 10.1016/j.virol.2013.08.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 07/29/2013] [Accepted: 08/06/2013] [Indexed: 11/26/2022]
Abstract
To study the membrane orientation of flavivirus non-structural proteins (NSPs) in the replication complex, the seven major West Nile (WN) NSPs were separately expressed in monkey cells, and their subcellular localization was investigated by imaging-based techniques. First, we observed by confocal microscopy that four small transmembrane proteins (TP) (NS2A, NS2B, NS4A, and NS4B) were located to the endoplasmic reticulum (ER), whereas the largest NSPs, NS1, NS3, and NS5 were not. We then analyzed the colocalization and the association of WN NSPs using the methods of confocal microscopy, fluorescence resonance energy transfer (FRET), and biologic fluorescence complementation (BiFC). Through these combined imaging techniques, protein-protein interactions (PPI) among WNNSPs were detected. Our data demonstrate that there are interactions between NS2A and NS4A, and interactions of NS2B with three other TPs (NS2A, NS4A, and NS4B) as well as the expected interaction with NS3. PPI between NS2A and NS4B or between NS4A and NS4B were not detected. By the criteria of these techniques, NS5 interacted only with NS3, and NS1 was not shown to be in close proximity with other NSPs. In addition, homo-oligomerization of some NSPs was observed and three-way interactions between NS2A, NS4A, and NA4B with NS2B-NS3 were also observed, respectively. Our results suggest that the four TPs are required for formation of transmembrane complex. NS2B protein seems to play a key role in bringing the TPs together on the ER membrane and in bridging the TPs with non-membrane-associated proteins (NS3 and NS5).
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Affiliation(s)
- Li Yu
- Laboratory of Vector-Borne Virus Diseases, Division of Viral Products, Office of Vaccines Research and Review, Microscopy and Imaging Core Facility, CBER, FDA, Bethesda, MD, USA.
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18
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Martínez-Fábregas J, Díaz-Moreno I, González-Arzola K, Janocha S, Navarro JA, Hervás M, Bernhardt R, Díaz-Quintana A, De la Rosa MÁ. New Arabidopsis thaliana cytochrome c partners: a look into the elusive role of cytochrome c in programmed cell death in plants. Mol Cell Proteomics 2013; 12:3666-76. [PMID: 24019145 DOI: 10.1074/mcp.m113.030692] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Programmed cell death is an event displayed by many different organisms along the evolutionary scale. In plants, programmed cell death is necessary for development and the hypersensitive response to stress or pathogenic infection. A common feature in programmed cell death across organisms is the translocation of cytochrome c from mitochondria to the cytosol. To better understand the role of cytochrome c in the onset of programmed cell death in plants, a proteomic approach was developed based on affinity chromatography and using Arabidopsis thaliana cytochrome c as bait. Using this approach, ten putative new cytochrome c partners were identified. Of these putative partners and as indicated by bimolecular fluorescence complementation, nine of them bind the heme protein in plant protoplasts and human cells as a heterologous system. The in vitro interaction between cytochrome c and such soluble cytochrome c-targets was further corroborated using surface plasmon resonance. Taken together, the results obtained in the study indicate that Arabidopsis thaliana cytochrome c interacts with several distinct proteins involved in protein folding, translational regulation, cell death, oxidative stress, DNA damage, energetic metabolism, and mRNA metabolism. Interestingly, some of these novel Arabidopsis thaliana cytochrome c-targets are closely related to those for Homo sapiens cytochrome c (Martínez-Fábregas et al., unpublished). These results indicate that the evolutionarily well-conserved cytosolic cytochrome c, appearing in organisms from plants to mammals, interacts with a wide range of targets on programmed cell death. The data have been deposited to the ProteomeXchange with identifier PXD000280.
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Affiliation(s)
- Jonathan Martínez-Fábregas
- Instituto de Bioquímica Vegetal y Fotosíntesis (IBVF), Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas (CSIC), Seville, 41092, Spain
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19
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Host IQGAP1 and Ebola virus VP40 interactions facilitate virus-like particle egress. J Virol 2013; 87:7777-80. [PMID: 23637409 DOI: 10.1128/jvi.00470-13] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have identified host IQGAP1 as an interacting partner for Ebola virus (EBOV) VP40, and its expression is required for EBOV VP40 virus-like particle (VLP) budding. IQGAP1 is involved in actin cytoskeletal remodeling during cell migration and formation of filopodia. The physical interaction and the functional requirement for IQGAP1 in EBOV VP40 VLP egress link virus budding to the cytoskeletal remodeling machinery. Consequently, this interaction represents a novel target for development of therapeutics to block budding and transmission of filoviruses.
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20
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Kodama Y, Hu CD. Bimolecular fluorescence complementation (BiFC): a 5-year update and future perspectives. Biotechniques 2013; 53:285-98. [PMID: 23148879 DOI: 10.2144/000113943] [Citation(s) in RCA: 192] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 09/28/2012] [Indexed: 11/23/2022] Open
Abstract
Over the past decade, bimolecular fluorescence complementation (BiFC) has emerged as a key technique to visualize protein-protein interactions in a variety of model organisms. The BiFC assay is based on reconstitution of an intact fluorescent protein when two complementary non-fluorescent fragments are brought together by a pair of interacting proteins. While the originally reported BiFC method has enabled the study of many protein-protein interactions, increasing demands to visualize protein-protein interactions under various physiological conditions have not only prompted a series of recent BiFC technology improvements, but also stimulated interest in developing completely new approaches. Here we review current BiFC technology, focusing on the development and improvement of BiFC systems, the understanding of split sites in fluorescent proteins, and enhancements in the signal-to-noise ratio. In addition, we provide perspectives on possible future improvements of the technique.
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Affiliation(s)
- Yutaka Kodama
- Center for Bioscience Research and Education, Utsunomiya University, Tochigi, Japan.
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21
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Role of interactions between Autographa californica multiple nucleopolyhedrovirus procathepsin and chitinase chitin-binding or active-site domains in viral cathepsin processing. J Virol 2013; 87:3471-83. [PMID: 23302896 DOI: 10.1128/jvi.01937-12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The binding of Autographa californica multiple nucleopolyhedrovirus chitinase (CHIA) to viral cathepsin protease progenitor (proV-CATH) governs cellular/endoplasmic reticulum (ER) coretention of CHIA and proV-CATH, thus coordinating simultaneous cellular release of both host tissue-degrading enzymes upon host cell death. CHIA is a proposed proV-CATH folding chaperone because insertional inactivation of chiA causes production of proV-CATH aggregates that are incompetent for proteolytic maturation into active V-CATH enzyme. We wanted to determine whether the N-terminal chitin-binding domain (CBD, 149 residues) and C-terminal CHIA active-site domain (ASD, 402 residues) of CHIA bind to proV-CATH independently of one another and whether either domain is dispensable for CHIA's putative proV-CATH folding chaperone activity. We demonstrate that N-terminally green fluorescent protein (GFP)-fused CHIA, ASD, and CBD each colocalize with proV-CATH-RFP in ER-like patterns and that both ASD and CBD independently associate with proV-CATH in vivo using bimolecular fluorescence complementation (BiFC) and in vitro using reciprocal nickel-histidine pulldown assays. Altogether, the data from colocalization, BiFC, and reciprocal copurification analyses suggest specific and independent interactions between proV-CATH and both domains of CHIA. These data also demonstrate that either CHIA domain is dispensable for normal proV-CATH processing. Furthermore, in contrast to prior evidence suggesting that a lack of chiA expression causes proV-CATH to become aggregated, insoluble, and unable to mature into V-CATH, a chiA deletion bacmid virus we engineered to express just v-cath produced soluble proV-CATH that was prematurely secreted from cells and proteolytically matured into active V-CATH enzyme.
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22
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Abstract
Mutations in the protein DJ-1 cause recessive forms of early onset familial Parkinson’s disease (PD). To date, most of the causative mutations studied destabilize formation of DJ-1 homodimers, which appears to be closely linked to its normal function in oxidative stress and other cellular processes. Despite the importance of understanding the dimerization dynamics of this protein, this aspect of DJ-1 biology has not previously been directly studied in living cells. Here, we use bimolecular fluorescence complementation to study DJ-1 dimerization and find not only that DJ-1 forms homodimers in living cells but that most PD causative DJ-1 mutations disrupt this process, including the L166P, M26I, L10P, and P158∆ mutations. Interestingly, the E64D mutant form of DJ-1 retains the ability to form homodimers. However, while wild-type DJ-1 dimers are stabilized under oxidative stress conditions, we find that the E64D mutation blocks this stabilization. Furthermore, our data show that the E64D mutation potentiates the formation of aggresomes containing DJ-1. We also observe that while the widely studied L166P mutation prevents DJ-1 from forming homodimers or heterodimers with wild-type protein, the mutant protein is able to partially disrupt formation of wild-type homodimers. In summary, by investigating DJ-1 dimerization in living cells, we have uncovered several novel properties of PD causative mutations in DJ-1, which may ultimately provide novel insight into PD pathogenesis and possible therapeutic options.
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23
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Kang MY, Kim HB, Piao C, Lee KH, Hyun JW, Chang IY, You HJ. The critical role of catalase in prooxidant and antioxidant function of p53. Cell Death Differ 2012; 20:117-29. [PMID: 22918438 DOI: 10.1038/cdd.2012.102] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The tumor suppressor p53 is an important regulator of intracellular reactive oxygen species (ROS) levels, although downstream mediators of p53 remain to be elucidated. Here, we show that p53 and its downstream targets, p53-inducible ribonucleotide reductase (p53R2) and p53-inducible gene 3 (PIG3), physically and functionally interact with catalase for efficient regulation of intracellular ROS, depending on stress intensity. Under physiological conditions, the antioxidant functions of p53 are mediated by p53R2, which maintains increased catalase activity and thereby protects against endogenous ROS. After genotoxic stress, high levels of p53 and PIG3 cooperate to inhibit catalase activity, leading to a shift in the oxidant/antioxidant balance toward an oxidative status, which could augment apoptotic cell death. These results highlight the essential role of catalase in p53-mediated ROS regulation and suggest that the p53/p53R2-catalase and p53/PIG3-catalase pathways are critically involved in intracellular ROS regulation under physiological conditions and during the response to DNA damage, respectively.
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Affiliation(s)
- M Y Kang
- DNA Damage Response Network Center, Chosun University School of Medicine, Gwangju, South Korea
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24
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Ishikawa-Ankerhold HC, Ankerhold R, Drummen GPC. Advanced fluorescence microscopy techniques--FRAP, FLIP, FLAP, FRET and FLIM. Molecules 2012; 17:4047-132. [PMID: 22469598 PMCID: PMC6268795 DOI: 10.3390/molecules17044047] [Citation(s) in RCA: 273] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 03/21/2012] [Accepted: 03/21/2012] [Indexed: 12/19/2022] Open
Abstract
Fluorescence microscopy provides an efficient and unique approach to study fixed and living cells because of its versatility, specificity, and high sensitivity. Fluorescence microscopes can both detect the fluorescence emitted from labeled molecules in biological samples as images or photometric data from which intensities and emission spectra can be deduced. By exploiting the characteristics of fluorescence, various techniques have been developed that enable the visualization and analysis of complex dynamic events in cells, organelles, and sub-organelle components within the biological specimen. The techniques described here are fluorescence recovery after photobleaching (FRAP), the related fluorescence loss in photobleaching (FLIP), fluorescence localization after photobleaching (FLAP), Förster or fluorescence resonance energy transfer (FRET) and the different ways how to measure FRET, such as acceptor bleaching, sensitized emission, polarization anisotropy, and fluorescence lifetime imaging microscopy (FLIM). First, a brief introduction into the mechanisms underlying fluorescence as a physical phenomenon and fluorescence, confocal, and multiphoton microscopy is given. Subsequently, these advanced microscopy techniques are introduced in more detail, with a description of how these techniques are performed, what needs to be considered, and what practical advantages they can bring to cell biological research.
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Affiliation(s)
- Hellen C. Ishikawa-Ankerhold
- Ludwig Maximilian University of Munich, Institute of Anatomy and Cell Biology, Schillerstr. 42, 80336 München, Germany
| | - Richard Ankerhold
- Carl Zeiss Microimaging GmbH, Kistlerhofstr. 75, 81379 München, Germany
| | - Gregor P. C. Drummen
- Bionanoscience and Bio-Imaging Program, Cellular Stress and Ageing Program, Bio&Nano-Solutions, Helmutstr. 3A, 40472 Düsseldorf, Germany
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25
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Tian G, Lu Q, Zhang L, Kohalmi SE, Cui Y. Detection of protein interactions in plant using a gateway compatible bimolecular fluorescence complementation (BiFC) system. J Vis Exp 2011:3473. [PMID: 21947026 PMCID: PMC3230203 DOI: 10.3791/3473] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
We have developed a BiFC technique to test the interaction between two proteins in vivo. This is accomplished by splitting a yellow fluorescent protein (YFP) into two non-overlapping fragments. Each fragment is cloned in-frame to a gene of interest. These constructs can then be co-transformed into Nicotiana benthamiana via Agrobacterium mediated transformation, allowing the transit expression of fusion proteins. The reconstitution of YFP signal only occurs when the inquest proteins interact (1-7). To test and validate the protein-protein interactions, BiFC can be used together with yeast two hybrid (Y2H) assay. This may detect indirect interactions which can be overlooked in the Y2H. Gateway technology is a universal platform that enables researchers to shuttle the gene of interest (GOI) into as many expression and functional analysis systems as possible(8,9). Both the orientation and reading frame can be maintained without using restriction enzymes or ligation to make expression-ready clones. As a result, one can eliminate all the re-sequencing steps to ensure consistent results throughout the experiments. We have created a series of Gateway compatible BiFC and Y2H vectors which provide researchers with easy-to-use tools to perform both BiFC and Y2H assays(10). Here, we demonstrate the ease of using our BiFC system to test protein-protein interactions in N. benthamiana plants.
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Affiliation(s)
- Gang Tian
- Department of Biology, University of Western Ontario, Canada
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Zhang Y, Gao P, Yuan JS. Plant protein-protein interaction network and interactome. Curr Genomics 2011; 11:40-6. [PMID: 20808522 PMCID: PMC2851115 DOI: 10.2174/138920210790218016] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 07/30/2009] [Accepted: 07/30/2009] [Indexed: 11/22/2022] Open
Abstract
Protein-protein interaction network represents an important aspect of systems biology. The understanding of the plant protein-protein interaction network and interactome will provide crucial insights into the regulation of plant developmental, physiological, and pathological processes. In this review, we will first define the concept of plant interactome and the protein-protein interaction network. The significance of the plant interactome study will be discussed. We will then compare the pros and cons for different strategies for interactome mapping including yeast two-hybrid system (Y2H), affinity purification mass spectrometry (AP-MS), bimolecular fluorescence complementation (BiFC), and in silico prediction. The application of these platforms on specific plant biology questions will be further discussed. The recent advancements revealed the great potential for plant protein-protein interaction network and interactome to elucidate molecular mechanisms for signal transduction, stress responses, cell cycle control, pattern formation, and others. Mapping the plant interactome in model species will provide important guideline for the future study of plant biology.
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Affiliation(s)
- Yixiang Zhang
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
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Hodgson JJ, Arif BM, Krell PJ. Interaction of Autographa californica multiple nucleopolyhedrovirus cathepsin protease progenitor (proV-CATH) with insect baculovirus chitinase as a mechanism for proV-CATH cellular retention. J Virol 2011; 85:3918-29. [PMID: 21289117 PMCID: PMC3126136 DOI: 10.1128/jvi.02165-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 01/20/2011] [Indexed: 11/20/2022] Open
Abstract
The insect baculovirus chitinase (CHIA) and cathepsin protease (V-CATH) enzymes cause terminal host insect liquefaction, enhancing the dissemination of progeny virions away from the host cadavers. Regulated and delayed cellular release of these host tissue-degrading enzymes ensures that liquefaction starts only after optimal viral replication has occurred. Baculoviral CHIA remains intracellular due to its C-terminal KDEL endoplasmic reticulum (ER) retention motif. However, the mechanism for cellular retention of the inactive V-CATH progenitor (proV-CATH) has not yet been determined. Signal peptide cleavage occurs upon cotranslational ER import of the v-cath-expressed protein, and ER-resident CHIA is needed for the folding of proV-CATH. Although this implies that CHIA and proV-CATH bind each other in the ER, the putative CHIA-proV-CATH interaction has not been experimentally verified. We demonstrate that the amino-terminal 22 amino acids (aa) of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) preproV-CATH are responsible for the entry of proV-CATH into the ER. Furthermore, the CHIA-green fluorescent protein (GFP) and proV-CATH-red fluorescent protein (RFP) fusion proteins colocalize in the ER. Using monomeric RFP (mRFP)-based bimolecular fluorescence complementation (BiFC), we determined that CHIA and proV-CATH interact directly with each other in the ER during virus replication. Moreover, reciprocal Ni/His pulldowns of His-tagged proteins confirmed the CHIA-proV-CATH interaction biochemically. The reciprocal copurification of CHIA and proV-CATH suggests a specific CHIA-proV-CATH interaction and corroborates our BiFC data. Deletion of the CHIA KDEL motif allowed for premature CHIA secretion from cells, and proV-CATH was similarly prematurely secreted from cells along with ΔKDEL-CHIA. These data suggest that CHIA and proV-CATH interact directly with each other and that this interaction aids the cellular retention of proV-CATH.
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Affiliation(s)
- Jeffrey J. Hodgson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1
| | - Basil M. Arif
- Laboratory for Molecular Virology, Great Lakes Forestry Centre, Sault Ste Marie, ON P6A 2E5, Canada
| | - Peter J. Krell
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1
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Vidi PA, Ejendal KF, Przybyla JA, Watts VJ. Fluorescent protein complementation assays: new tools to study G protein-coupled receptor oligomerization and GPCR-mediated signaling. Mol Cell Endocrinol 2011; 331:185-93. [PMID: 20654687 PMCID: PMC2990800 DOI: 10.1016/j.mce.2010.07.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 06/07/2010] [Accepted: 07/13/2010] [Indexed: 11/29/2022]
Abstract
G protein-coupled receptor (GPCR) signaling is mediated by protein-protein interactions at multiple levels. The characterization of the corresponding protein complexes is therefore paramount to the basic understanding of GPCR-mediated signal transduction. The number of documented interactions involving GPCRs is rapidly growing, and appreciating the functional significance of these complexes is clearly the next challenge. New experimental approaches including protein complementation assays (PCAs) have recently been used to examine the composition, plasma membrane targeting, and desensitization of protein complexes involved in GPCR signaling. These methods also hold promise for better understanding of drug-induced effects on GPCR interactions. This review focuses on the application of fluorescent PCAs for the study of GPCR signaling. Potential applications of PCAs in high-content screens are also presented. Non-fluorescent PCA techniques as well as combined assays for the detection of ternary and quaternary protein complexes are briefly discussed.
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Affiliation(s)
- Pierre-Alexandre Vidi
- Department of Basic Medical Sciences, School of Veterinary Medicine, Purdue University
| | - Karin F.K. Ejendal
- Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Purdue University
| | - Julie A. Przybyla
- Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Purdue University
| | - Val J. Watts
- Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Purdue University
- Correspondence should be addressed to Dr. Val J. Watts, Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907-2051. Phone: (765) 496-3872, Fax: (765) 494-1414
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Vidi PA, Przybyla JA, Hu CD, Watts VJ. Visualization of G protein-coupled receptor (GPCR) interactions in living cells using bimolecular fluorescence complementation (BiFC). ACTA ACUST UNITED AC 2010; Chapter 5:Unit 5.29. [PMID: 20373507 DOI: 10.1002/0471142301.ns0529s51] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Members of the G protein-coupled receptor (GPCR) superfamily have been shown to homo- and hetero-oligomerize both in vitro and in vivo. Although the functional and pharmacological significance of GPCR oligomerization is far from being completely understood, evidence suggests that, depending on the receptor, oligomerization may influence ligand binding, G protein coupling, and receptor targeting. Bimolecular fluorescence complementation (BiFC) is a technique based on the complementation of fragments from fluorescent proteins that allows the measurement and visualization of protein interactions in living cells. It can be extended to the simultaneous detection of distinct protein-protein interactions using a multicolor setup. This unit describes the application of BiFC and multicolor BiFC to the visualization of GPCR oligomerization in a neuronal cell model. Oligomerization of GPCR fusions to BiFC tags is visualized and measured using fluorescence microscopy and fluorometry. The effect of ligands on the relative formation of distinct oligomeric species is monitored with a ratiometric multicolor BiFC approach.
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30
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Gao X, Wan F, Mateo K, Callegari E, Wang D, Deng W, Puente J, Li F, Chaussee MS, Finlay BB, Lenardo MJ, Hardwidge PR. Bacterial effector binding to ribosomal protein s3 subverts NF-kappaB function. PLoS Pathog 2009; 5:e1000708. [PMID: 20041225 PMCID: PMC2791202 DOI: 10.1371/journal.ppat.1000708] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 11/24/2009] [Indexed: 02/02/2023] Open
Abstract
Enteric bacterial pathogens cause food borne disease, which constitutes an enormous economic and health burden. Enterohemorrhagic Escherichia coli (EHEC) causes a severe bloody diarrhea following transmission to humans through various means, including contaminated beef and vegetable products, water, or through contact with animals. EHEC also causes a potentially fatal kidney disease (hemolytic uremic syndrome) for which there is no effective treatment or prophylaxis. EHEC and other enteric pathogens (e.g., enteropathogenic E. coli (EPEC), Salmonella, Shigella, Yersinia) utilize a type III secretion system (T3SS) to inject virulence proteins (effectors) into host cells. While it is known that T3SS effectors subvert host cell function to promote diarrheal disease and bacterial transmission, in many cases, the mechanisms by which these effectors bind to host proteins and disrupt the normal function of intestinal epithelial cells have not been completely characterized. In this study, we present evidence that the E. coli O157:H7 nleH1 and nleH2 genes encode T3SS effectors that bind to the human ribosomal protein S3 (RPS3), a subunit of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB) transcriptional complexes. NleH1 and NleH2 co-localized with RPS3 in the cytoplasm, but not in cell nuclei. The N-terminal region of both NleH1 and NleH2 was required for binding to the N-terminus of RPS3. NleH1 and NleH2 are autophosphorylated Ser/Thr protein kinases, but their binding to RPS3 is independent of kinase activity. NleH1, but not NleH2, reduced the nuclear abundance of RPS3 without altering the p50 or p65 NF-kappaB subunits or affecting the phosphorylation state or abundance of the inhibitory NF-kappaB chaperone IkappaBalpha NleH1 repressed the transcription of a RPS3/NF-kappaB-dependent reporter plasmid, but did not inhibit the transcription of RPS3-independent reporters. In contrast, NleH2 stimulated RPS3-dependent transcription, as well as an AP-1-dependent reporter. We identified a region of NleH1 (N40-K45) that is at least partially responsible for the inhibitory activity of NleH1 toward RPS3. Deleting nleH1 from E. coli O157:H7 produced a hypervirulent phenotype in a gnotobiotic piglet model of Shiga toxin-producing E. coli infection. We suggest that NleH may disrupt host innate immune responses by binding to a cofactor of host transcriptional complexes.
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Affiliation(s)
- Xiaofei Gao
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Fengyi Wan
- Laboratory of Immunology, National Institutes of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - Kristina Mateo
- Department of Veterinary Science, South Dakota State University, Brookings, South Dakota, United States of America
| | - Eduardo Callegari
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, United States of America
| | - Dan Wang
- Department of Veterinary Science, South Dakota State University, Brookings, South Dakota, United States of America
| | - Wanyin Deng
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jose Puente
- Departamento de Microbiología Molecular, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Feng Li
- Department of Veterinary Science, South Dakota State University, Brookings, South Dakota, United States of America
| | - Michael S. Chaussee
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, United States of America
| | - B. Brett Finlay
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael J. Lenardo
- Laboratory of Immunology, National Institutes of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - Philip R. Hardwidge
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
- * E-mail:
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Zinc coordination is required for and regulates transcription activation by Epstein-Barr nuclear antigen 1. PLoS Pathog 2009; 5:e1000469. [PMID: 19521517 PMCID: PMC2690687 DOI: 10.1371/journal.ppat.1000469] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Accepted: 05/12/2009] [Indexed: 12/17/2022] Open
Abstract
Epstein-Barr Nuclear Antigen 1 (EBNA1) is essential for Epstein-Barr virus to immortalize naïve B-cells. Upon binding a cluster of 20 cognate binding-sites termed the family of repeats, EBNA1 transactivates promoters for EBV genes that are required for immortalization. A small domain, termed UR1, that is 25 amino-acids in length, has been identified previously as essential for EBNA1 to activate transcription. In this study, we have elucidated how UR1 contributes to EBNA1's ability to transactivate. We show that zinc is necessary for EBNA1 to activate transcription, and that UR1 coordinates zinc through a pair of essential cysteines contained within it. UR1 dimerizes upon coordinating zinc, indicating that EBNA1 contains a second dimerization interface in its amino-terminus. There is a strong correlation between UR1-mediated dimerization and EBNA1's ability to transactivate cooperatively. Point mutants of EBNA1 that disrupt zinc coordination also prevent self-association, and do not activate transcription cooperatively. Further, we demonstrate that UR1 acts as a molecular sensor that regulates the ability of EBNA1 to activate transcription in response to changes in redox and oxygen partial pressure (pO2). Mild oxidative stress mimicking such environmental changes decreases EBNA1-dependent transcription in a lymphoblastoid cell-line. Coincident with a reduction in EBNA1-dependent transcription, reductions are observed in EBNA2 and LMP1 protein levels. Although these changes do not affect LCL survival, treated cells accumulate in G0/G1. These findings are discussed in the context of EBV latency in body compartments that differ strikingly in their pO2 and redox potential. Epstein-Barr virus (EBV) infects human B-cells and immortalizes them. Immortalization results in diseases that range from infectious mononucleosis to malignancies such as lymphomas. During immortalization, EBV expresses a small number of viral genes that modulate cellular proliferation and differentiation. One of the genes expressed by EBV, Epstein-Barr nuclear antigen 1 (EBNA1), activates the expression of the other viral genes required for immortalization. In this report, we have explored the mechanism by which EBNA1 activates gene expression. We have determined that EBNA1 uses the micronutrient zinc to self-associate, and that self-association is necessary for it to activate gene expression. Further, we have determined that environmental conditions such as oxygen tension and oxidative stress modulate EBNA1's capacity to self-associate, and therefore to activate gene expression. The gene expression profile and proliferative phenotype of EBV-infected cells is known to vary in differing environmental niches in the human body, such as lymph nodes and in peripheral circulation. We interpret our results to postulate that these differences arise as a consequence of varying oxygen tension in these microenvironments on EBNA1's capacity to activate viral gene expression. Our findings can be exploited to devise novel therapeutics against EBV-associated diseases that target EBNA1 through oxidative stress.
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Vidi PA, Watts VJ. Fluorescent and bioluminescent protein-fragment complementation assays in the study of G protein-coupled receptor oligomerization and signaling. Mol Pharmacol 2009; 75:733-9. [PMID: 19141658 DOI: 10.1124/mol.108.053819] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Most cellular functions, including signaling by G protein-coupled receptors (GPCRs), are mediated by protein-protein interactions, making the identification and localization of protein complexes key to the understanding of cellular processes. In complement to traditional biochemical techniques, noninvasive resonance energy transfer (RET) and protein-fragment complementation assays (PCAs) now allow protein interactions to be detected in the context of living cells. In this review, fluorescent and bioluminescent PCAs are discussed and their application illustrated with studies on GPCR signaling. Newly developed techniques combining PCA and RET assays for the detection of ternary and quaternary protein complexes are also presented.
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Affiliation(s)
- Pierre-Alexandre Vidi
- Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Purdue University, West Lafayette, Indiana 47907-2051, USA
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Gandia J, Galino J, Amaral OB, Soriano A, Lluís C, Franco R, Ciruela F. Detection of higher-order G protein-coupled receptor oligomers by a combined BRET-BiFC technique. FEBS Lett 2008; 582:2979-84. [PMID: 18675812 DOI: 10.1016/j.febslet.2008.07.045] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 07/01/2008] [Accepted: 07/11/2008] [Indexed: 01/25/2023]
Abstract
Despite some caveats, G protein-coupled receptor oligomerization is a phenomenon that is becoming largely accepted. Within these oligomers, however, stoichiometry remains to be elucidated. Here, by using bimolecular fluorescence complementation, we visualized adenosine A(2A) receptor homodimers in living cells, showing no apparent difference in the subcellular distribution when compared to the YFP-labelled adenosine A(2A) receptor protomer. Interestingly, the combination of bimolecular fluorescence complementation and bioluminescence resonance energy transfer techniques allowed us to detect the occurrence of adenosine A(2A) receptors oligomers containing more than two protomers. These results provide new insights into the molecular composition of G protein-coupled receptor oligomers.
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Affiliation(s)
- Jorge Gandia
- Departament Patologia i Terapèutica Experimental, Facultat de Medicina, Universitat de Barcelona, Pavelló de Govern, L'Hospitalet de Llobregat, 08907 Barcelona, Spain
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Bimolecular fluorescence complementation (BiFC) analysis of protein interactions in Caenorhabditis elegans. Methods 2008; 45:185-91. [PMID: 18586101 DOI: 10.1016/j.ymeth.2008.06.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 05/28/2008] [Accepted: 06/16/2008] [Indexed: 11/24/2022] Open
Abstract
Protein interactions are essential components of signal transduction in cells. With the progress in genome-wide yeast two hybrid screens and proteomics analyses, many protein interaction networks have been generated. These analyses have identified hundreds and thousands of interactions in cells and organisms, creating a challenge for further validation under physiological conditions. The bimolecular fluorescence complementation (BiFC) assay is such an assay that meets this need. The BiFC assay is based on the principle of protein fragment complementation, in which two non-fluorescent fragments derived from a fluorescent protein are fused to a pair of interacting partners. When the two partners interact, the two non-fluorescent fragments are brought into proximity and an intact fluorescent protein is reconstituted. Hence, the reconstituted fluorescent signals reflect the interaction of two proteins under study. Over the past six years, the BiFC assay has been used for visualization of protein interactions in living cells and organisms, including our application of the BiFC assay to the transparent nematode Caenorhabditis elegans. We have demonstrated that BiFC analysis in C. elegans provides a direct means to identify and validate protein interactions in living worms and allows visualization of temporal and spatial interactions. Here, we provide a guideline for the implementation of BiFC analysis in living worms and discuss the factors that are critical for BiFC analysis.
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