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Yang Z, Chan DC. Development of a signal-integrating reporter to monitor mitochondria-ER contacts. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580376. [PMID: 38405790 PMCID: PMC10888864 DOI: 10.1101/2024.02.14.580376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Mitochondria-ER contact sites (MERCS) serve as hotspots for important cellular processes, including calcium homeostasis, phospholipid homeostasis, mitochondria dynamics, and mitochondrial quality control. MERCS reporters based on complementation of GFP fragments have been designed to visualize MERCS in real-time, but we find that they do not accurately respond to changes in MERCS content. Here, we utilize split LacZ complementing fragments to develop the first MERCS reporter system (termed SpLacZ-MERCS) that continuously integrates the MERCS information within a cell and generates a fluorescent output. Our system exhibits good organelle targeting, no artifactual tethering, and effective, dynamic tracking of the MERCS level in single cells. The SpLacZ-MERCS reporter was validated by drug treatments and genetic perturbations known to affect mitochondria-ER contacts. The signal-integrating nature of SpLacZ-MERCS may enable systematic identification of genes and drugs that regulate mitochondria-ER interactions. Our successful application of the split LacZ complementation strategy to study MERCS may be extended to study other forms of inter-organellar crosstalk.
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Galactosidase-catalyzed fluorescence amplification method (GAFAM): sensitive fluorescent immunohistochemistry using novel fluorogenic β-galactosidase substrates and its application in multiplex immunostaining. Histochem Cell Biol 2023; 159:233-246. [PMID: 36374321 DOI: 10.1007/s00418-022-02162-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2022] [Indexed: 11/16/2022]
Abstract
Multiplex immunohistochemistry/multiplex immunofluorescence (mIHC/mIF) enables the simultaneous detection of multiple markers in a single tissue section by visualizing the markers in different colors. Currently, tyramide signal amplification (TSA) is the most commonly used method because it is heat resistant to multiplexing. SPiDER-βGal (6'-(diethylamino)-4'-(fluoromethyl)spiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3'-yl β-D-galactopyranoside), a novel fluorogenic substrate of β-galactosidase (β-gal) was reported recently. Its properties are favorable for application in sensitive mIF based on quinone methide chemistry. Combining SPiDER-βGal with its related substrates, a novel, sensitive fluorescent IHC method for formalin-fixed paraffin-embedded (FFPE) sections was developed, named the galactosidase-catalyzed fluorescence amplification method (GAFAM). Evaluation of GAFAM indicated the following characteristics: (1) the entire GAFAM procedure was complete within a few hours; (2) the optimal working concentration of the substrates was 20 μM; (3) the fluorescent product was heat resistant; (4) the GAFAM exhibited sensitivity comparable with that of TSA, which was higher than that of conventional IF; and (5) the GAFAM was applicable to mIF and multispectral imaging. GAFAM is expected to be applicable to IF (or mIF in combination with TSA), and is a promising tool for facilitating morphological research in various fields of life science.
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Zhang Y, Wang Y, Xu L, Lou C, Ouyang Q, Qian L. Paired dCas9 design as a nucleic acid detection platform for pathogenic strains. Methods 2022; 203:70-77. [PMID: 34090973 DOI: 10.1016/j.ymeth.2021.06.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/03/2021] [Accepted: 06/01/2021] [Indexed: 12/26/2022] Open
Abstract
The wide application of molecular beacon probes in specific DNA detection, especially in the fast prototyping of pathogen DNA detection kits in point-of-care diagnostics, has been hindered by the nonflexible choice of target sequences and the unstable fluorophore output. We developed an in vitro DNA detection system consisting of a pair of dCas9 proteins linked to split halves of luciferase, named the Paired dCas9 (PC) reporter. Co-localization of the reporter pair to a ~46 bp target sequence defined by two single guide RNAs (sgRNAs) activated luciferase which subsequently generated highly intensified luminescent signals. Combined with an array design and statistical analyses, the PC reporter system could be programmed to access sequence information across the entire genome of the pathogenic Mycobacterium tuberculosis H37Rv strain. These findings suggest great potential for the PC reporter in effective and affordable in vitro nucleic acid detection technologies. In this article we highlighted the systems design from our previous researchworkon the PC reporter (Zhang et al, 2015)with a focuson methodology.
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Affiliation(s)
- Yihao Zhang
- Center for Quantitative Biology and Peking-Tsinghua Joint Center for Life Sciences, Peking University, Beijing 100871, China; Peking University Team for 2015 International Genetically Engineered Machine Competition (iGEM 2015), Beijing 100871, China
| | - Yu Wang
- Peking University Team for 2015 International Genetically Engineered Machine Competition (iGEM 2015), Beijing 100871, China
| | - Luze Xu
- Peking University Team for 2015 International Genetically Engineered Machine Competition (iGEM 2015), Beijing 100871, China
| | - Chunbo Lou
- CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics, Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Qi Ouyang
- Center for Quantitative Biology and Peking-Tsinghua Joint Center for Life Sciences, Peking University, Beijing 100871, China; The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Long Qian
- Center for Quantitative Biology and Peking-Tsinghua Joint Center for Life Sciences, Peking University, Beijing 100871, China.
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Samavarchi-Tehrani P, Samson R, Gingras AC. Proximity Dependent Biotinylation: Key Enzymes and Adaptation to Proteomics Approaches. Mol Cell Proteomics 2020; 19:757-773. [PMID: 32127388 PMCID: PMC7196579 DOI: 10.1074/mcp.r120.001941] [Citation(s) in RCA: 110] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/25/2020] [Indexed: 12/12/2022] Open
Abstract
The study of protein subcellular distribution, their assembly into complexes and the set of proteins with which they interact with is essential to our understanding of fundamental biological processes. Complementary to traditional assays, proximity-dependent biotinylation (PDB) approaches coupled with mass spectrometry (such as BioID or APEX) have emerged as powerful techniques to study proximal protein interactions and the subcellular proteome in the context of living cells and organisms. Since their introduction in 2012, PDB approaches have been used in an increasing number of studies and the enzymes themselves have been subjected to intensive optimization. How these enzymes have been optimized and considerations for their use in proteomics experiments are important questions. Here, we review the structural diversity and mechanisms of the two main classes of PDB enzymes: the biotin protein ligases (BioID) and the peroxidases (APEX). We describe the engineering of these enzymes for PDB and review emerging applications, including the development of PDB for coincidence detection (split-PDB). Lastly, we briefly review enzyme selection and experimental design guidelines and reflect on the labeling chemistries and their implication for data interpretation.
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Affiliation(s)
| | - Reuben Samson
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Canada.
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Wang T, Yang N, Liang C, Xu H, An Y, Xiao S, Zheng M, Liu L, Wang G, Nie L. Detecting Protein-Protein Interaction Based on Protein Fragment Complementation Assay. Curr Protein Pept Sci 2020; 21:598-610. [PMID: 32053071 DOI: 10.2174/1389203721666200213102829] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/10/2020] [Accepted: 01/13/2020] [Indexed: 11/22/2022]
Abstract
Proteins are the most critical executive molecules by responding to the instructions stored in the genetic materials in any form of life. More frequently, proteins do their jobs by acting as a roleplayer that interacts with other protein(s), which is more evident when the function of a protein is examined in the real context of a cell. Identifying the interactions between (or amongst) proteins is very crucial for the biochemistry investigation of an individual protein and for the attempts aiming to draw a holo-picture for the interacting members at the scale of proteomics (or protein-protein interactions mapping). Here, we introduced the currently available reporting systems that can be used to probe the interaction between candidate protein pairs based on the fragment complementation of some particular proteins. Emphasis was put on the principles and details of experimental design. These systems are dihydrofolate reductase (DHFR), β-lactamase, tobacco etch virus (TEV) protease, luciferase, β- galactosidase, GAL4, horseradish peroxidase (HRP), focal adhesion kinase (FAK), green fluorescent protein (GFP), and ubiquitin.
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Affiliation(s)
- Tianwen Wang
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Ningning Yang
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Chen Liang
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Hongjv Xu
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Yafei An
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Sha Xiao
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Mengyuan Zheng
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Lu Liu
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Gaozhan Wang
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
| | - Lei Nie
- College of Life Sciences, and Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China
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Hamdan H, Patyal P, Kockara NT, Wight PA. The wmN1 enhancer region in intron 1 is required for expression of human PLP1. Glia 2018; 66:1763-1774. [PMID: 29683207 DOI: 10.1002/glia.23339] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/10/2018] [Accepted: 03/22/2018] [Indexed: 12/13/2022]
Abstract
The myelin proteolipid protein gene (PLP1) encodes the most abundant protein present in myelin from the central nervous system (CNS). Its expression must be tightly controlled as evidenced by mutations that alter PLP1 dosage; both overexpression (elevated PLP1 copy number) and lack thereof (PLP1 deletion) result in X-linked genetic disorders in man. However, not much is known about the mechanisms that govern expression of the human gene. To address this, transgenic mice were generated which utilize human PLP1 (hPLP1) sequences (proximal 6.2 kb of 5'-flanking DNA to the first 38 bp of exon 2) to drive expression of a lacZ reporter cassette. LoxP sites were incorporated around a 1.5-kb section of hPLP1 intron 1 since it contains sequence orthologous to the wmN1 region from mouse which, previously, was shown to augment expression of a minimally-promoted transgene coincident with the active myelination period of CNS development. Eight transgenic lines were generated with the parental, 6.2hPLP(+)Z/FL, transgene. All lines expressed the transgene appropriately in brain as evidenced by staining with X-gal in white matter regions and olfactory bulb. Removal of the "wmN1" region from 6.2hPLP(+)Z/FL with a ubiquitously expressed Cre-driver caused a dramatic reduction in transgene activity. These results demonstrate for the first time that the wmN1 enhancer region: (1) is functional in hPLP1; (2) works in collaboration with its native promoter-not just a basal heterologous promoter; (3) is required for high levels of hPLP1 gene activity; (4) has a broader effect, both spatially and temporally, than originally projected with mPlp1.
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Affiliation(s)
- Hamdan Hamdan
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Pankaj Patyal
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Neriman T Kockara
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Patricia A Wight
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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Hudson AO, Harkness TCM, Savka MA. Functional Complementation Analysis (FCA): A Laboratory Exercise Designed and Implemented to Supplement the Teaching of Biochemical Pathways. J Vis Exp 2016:53850. [PMID: 27403640 PMCID: PMC4993271 DOI: 10.3791/53850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023] Open
Abstract
Functional complementation assay (FCA) is an in vivo assay that is widely used to elucidate the function/role of genes/enzymes. This technique is very common in biochemistry, genetics and many other disciplines. A comprehensive overview of the technique to supplement the teaching of biochemical pathways pertaining to amino acids, peptidoglycan and the bacterial stringent response is reported in this manuscript. Two cDNAs from the model plant organism Arabidopsis thaliana that are involved in the metabolism of lysine (L,L-diaminopimelate aminotransferase (dapL) and tyrosine aminotransferase (tyrB) involved in the metabolism of tyrosine and phenylalanine are highlighted. In addition, the bacterial peptidoglycan anabolic pathway is highlighted through the analysis of the UDP-N-acetylmuramoyl-L-alanyl-D-glutamate-meso-2,6-diaminopimelate ligase (murE) gene from the bacterium Verrucomicrobium spinosum involved in the cross-linking of peptidoglycan. The bacterial stringent response is also reported through the analysis of the rsh (relA/spoT homolog) bifunctional gene responsible for a hyper-mucoid phenotype in the bacterium Novosphingobium sp. Four examples of FCA are presented. The video will focus on three of them, namely lysine, peptidoglycan and the stringent response.
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Affiliation(s)
- André O Hudson
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology;
| | - Taylor C M Harkness
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology
| | - Michael A Savka
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology
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Mogalisetti P, Walt DR. Stoichiometry of the α-complementation reaction of Escherichia coli β-galactosidase as revealed through single-molecule studies. Biochemistry 2015; 54:1583-8. [PMID: 25668156 DOI: 10.1021/bi5015024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The α-complementation reaction of β-galactosidase was studied at single-molecule resolution using arrays of femtoliter-sized wells. Single molecules of the complementation species were observed to be stable for long periods of time, demonstrating that the α-complementation reaction is irreversible. By directly counting the number of active molecules formed in the complementation reaction when different concentrations of enzyme acceptor (EA) and enzyme donor (ED) are used, we deduce that the EA:ED ratio in the complementation species is 4:1.
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Affiliation(s)
- Pratyusha Mogalisetti
- Department of Chemistry, Tufts University , 62 Talbot Avenue, Medford, Massachusetts 02155, United States
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Hamdan H, Kockara NT, Jolly LA, Haun S, Wight PA. Control of human PLP1 expression through transcriptional regulatory elements and alternatively spliced exons in intron 1. ASN Neuro 2015; 7:7/1/1759091415569910. [PMID: 25694552 PMCID: PMC4342368 DOI: 10.1177/1759091415569910] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
These authors contributed equally to this work. Although the myelin proteolipid protein gene (PLP1) encodes the most abundant protein in central nervous system (CNS) myelin, not much is known about the mechanisms that govern expression of the human gene (hPLP1). Much more is known about the processes that regulate Plp1 gene expression in rodents. From studies with Plp1-lacZ transgenic mice, it was determined that the first intron of mouse Plp1 (mPlp1) is required to attain high levels of expression in brain, concurrent with the active myelination period. Other studies have suggested that within mPlp1 intron 1 (>8 kb) lie several regions with enhancer-like activity. To test whether these sequences (and possibly others) in hPLP1 intron 1 are functional, deletion-transfection analysis was performed with hPLP1-lacZ constructs that contain various portions of the intron, or lack it altogether. Results presented here demonstrate the importance of hPLP1 intron 1 in achieving maximal levels of expression in the immortalized oligodendroglial cell line, Oli-neu. Deletion analysis indicates that the intron contains multiple positive regulatory elements which are active in Oli-neu cells. Some of these elements appear to be functionally conserved between human and mouse, while others are not. Furthermore, our studies demonstrate that multiple splice variants can be formed due to inclusion of extra (supplementary) exons from what is classically thought of as hPLP1 intron 1. Thus, splicing of these novel exons (which are not recognized as such in mPlp1 due to lack of conserved splice sites) must utilize factors common to both human and mouse since Oli-neu cells are of mouse origin.
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Affiliation(s)
- Hamdan Hamdan
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Neriman T Kockara
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Lee Ann Jolly
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Shirley Haun
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Patricia A Wight
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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Development of a lentivirus vector-based assay for non-destructive monitoring of cell fusion activity. PLoS One 2014; 9:e102433. [PMID: 25028973 PMCID: PMC4100873 DOI: 10.1371/journal.pone.0102433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 06/19/2014] [Indexed: 02/06/2023] Open
Abstract
Cell-to-cell fusion can be quantified by endowing acceptor and donor cells with latent reporter genes/proteins and activators of these genes/proteins, respectively. One way to accomplish this goal is by using a bipartite lentivirus vector (LV)-based cell fusion assay system in which the cellular fusion partners are transduced with a flippase-activatable Photinus pyralis luciferase (PpLuc) expression unit (acceptor cells) or with a recombinant gene encoding FLPeNLS+, a nuclear-targeted and molecularly evolved version of flippase (donor cells). Fusion of both cell populations will lead to the FLPe-dependent generation of a functional PpLuc gene. PpLuc activity is typically measured in cell lysates, precluding consecutive analysis of one cell culture. Therefore, in this study the PpLuc-coding sequence was replaced by that of Gaussia princeps luciferase (GpLuc), a secretory protein allowing repeated analysis of the same cell culture. In myotubes the spread of FLPeNLS+ may be limited due to its nuclear localization signal (NLS) causing low signal outputs. To test this hypothesis, myoblasts were transduced with LVs encoding either FLPeNLS+ or an NLS-less version of FLPe (FLPeNLS−) and subsequently co-cultured in different ratios with myoblasts containing the FLPe-activatable GpLuc expression cassette. At different times after induction of cell-to-cell fusion the GpLuc activity in the culture medium was determined. FLPeNLS+ and FLPeNLS− both activated the latent GpLuc gene but when the percentage of FLPe-expressing myoblasts was limiting, FLPeNLS+ generally yielded slightly higher signals than FLPeNLS− while at low acceptor-to-donor cell ratios FLPeNLS− was usually superior. The ability of FLPeNLS+ to spread through myofibers and to induce reporter gene expression is thus not limited by its NLS. However, at high FLPe concentrations the presence of the NLS negatively affected reporter gene expression. In summary, a rapid and simple chemiluminescence assay for quantifying cell-to-cell fusion progression based on GpLuc has been developed.
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Skeldal S, Sykes AM, Glerup S, Matusica D, Palstra N, Autio H, Boskovic Z, Madsen P, Castrén E, Nykjaer A, Coulson EJ. Mapping of the interaction site between sortilin and the p75 neurotrophin receptor reveals a regulatory role for the sortilin intracellular domain in p75 neurotrophin receptor shedding and apoptosis. J Biol Chem 2012; 287:43798-809. [PMID: 23105113 DOI: 10.1074/jbc.m112.374710] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurotrophins comprise a group of neuronal growth factors that are essential for the development and maintenance of the nervous system. However, the immature pro-neurotrophins promote apoptosis by engaging in a complex with sortilin and the p75 neurotrophin receptor (p75(NTR)). To identify the interaction site between sortilin and p75(NTR), we analyzed binding between chimeric receptor constructs and truncated p75(NTR) variants by co-immunoprecipitation experiments, surface plasmon resonance analysis, and FRET. We found that complex formation between sortilin and p75(NTR) relies on contact points in the extracellular domains of the receptors. We also determined that the interaction critically depends on an extracellular juxtamembrane 23-amino acid sequence of p75(NTR). Functional studies further revealed an important regulatory function of the sortilin intracellular domain in p75(NTR)-regulated intramembrane proteolysis and apoptosis. Thus, although the intracellular domain of sortilin does not contribute to p75(NTR) binding, it does regulate the rates of p75(NTR) cleavage, which is required to mediate pro-neurotrophin-stimulated cell death.
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Affiliation(s)
- Sune Skeldal
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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Torkzadeh-Mahani M, Ataei F, Nikkhah M, Hosseinkhani S. Design and development of a whole-cell luminescent biosensor for detection of early-stage of apoptosis. Biosens Bioelectron 2012; 38:362-8. [DOI: 10.1016/j.bios.2012.06.034] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 06/06/2012] [Accepted: 06/14/2012] [Indexed: 12/20/2022]
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Chenaux G, Henkemeyer M. Forward signaling by EphB1/EphB2 interacting with ephrin-B ligands at the optic chiasm is required to form the ipsilateral projection. Eur J Neurosci 2011; 34:1620-33. [PMID: 22103419 PMCID: PMC3228319 DOI: 10.1111/j.1460-9568.2011.07845.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
EphB receptor tyrosine kinases direct axonal pathfinding through interactions with ephrin-B proteins following axon-cell contact. As EphB:ephrin-B binding leads to bidirectional signals, the contributions of signaling into the Eph-expressing cell (forward signaling) or the ephrin-expressing cell (reverse signaling) cannot be assigned using traditional protein null alleles. To determine if EphB1 is functioning solely as a receptor during axon pathfinding, a new knock-in mutant mouse was created, EphB1(T-lacZ), which expresses an intracellular-truncated EphB1-β-gal fusion protein from the endogenous locus. As in the EphB1(-/-) protein null animals, the EphB1(T-lacZ/T-lacZ) homozygotes fail to form the ipsilateral projecting subpopulation of retinal ganglion cell axons. This indicates that reverse signaling through the extracellular domain of EphB1 is not required for proper axon pathfinding of retinal axons at the optic chiasm. Further analysis of other EphB and ephrin-B mutant mice shows that EphB1 is the preferred receptor of ephrin-B2 and, to a lesser degree, ephrin-B1 in mediating axon guidance at the optic chiasm despite the coexpression of EphB2 in the same ipsilaterally projecting retinal axons.
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Affiliation(s)
- George Chenaux
- Department of Developmental Biology and Kent Waldrep Foundation Center for Basic Research on Nerve Growth and Regeneration University of Texas Southwestern Medical Center 6000 Harry Hines Blvd. Dallas, TX 75390-9133, United States of America
| | - Mark Henkemeyer
- Department of Developmental Biology and Kent Waldrep Foundation Center for Basic Research on Nerve Growth and Regeneration University of Texas Southwestern Medical Center 6000 Harry Hines Blvd. Dallas, TX 75390-9133, United States of America
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Jochmans D, Anders M, Keuleers I, Smeulders L, Kräusslich HG, Kraus G, Müller B. Selective killing of human immunodeficiency virus infected cells by non-nucleoside reverse transcriptase inhibitor-induced activation of HIV protease. Retrovirology 2010; 7:89. [PMID: 20950436 PMCID: PMC2974656 DOI: 10.1186/1742-4690-7-89] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 10/15/2010] [Indexed: 12/03/2022] Open
Abstract
Background Current antiretroviral therapy against human immunodeficiency virus (HIV-1) reduces viral load and thereby prevents viral spread, but it cannot eradicate proviral genomes from infected cells. Cells in immunological sanctuaries as well as cells producing low levels of virus apparently contribute to a reservoir that maintains HIV persistence in the presence of highly active antiretroviral therapy. Thus, accelerated elimination of virus producing cells may represent a complementary strategy to control HIV infection. Here we sought to exploit HIV protease (PR) related cytotoxicity in order to develop a strategy for drug induced killing of HIV producing cells. PR processes the viral Gag and Gag-Pol polyproteins during virus maturation, but is also implicated in killing of virus producing cells through off-target cleavage of host proteins. It has been observed previously that micromolar concentrations of certain non-nucleoside reverse transcriptase inhibitors (NNRTIs) can stimulate intracellular PR activity, presumably by enhancing Gag-Pol dimerization. Results Using a newly developed cell-based assay we compared the degree of PR activation displayed by various NNRTIs. We identified inhibitors showing higher potency with respect to PR activation than previously described for NNRTIs, with the most potent compounds resulting in ~2-fold increase of the Gag processing signal at 250 nM. The degree of enhancement of intracellular Gag processing correlated with the compound's ability to enhance RT dimerization in a mammalian two-hybrid assay. Compounds were analyzed for their potential to mediate specific killing of chronically infected MT-4 cells. Levels of cytotoxicity on HIV infected cells determined for the different NNRTIs corresponded to the relative degree of drug induced intracellular PR activation, with CC50 values ranging from ~0.3 μM to above the tested concentration range (10 μM). Specific cytotoxicity was reverted by addition of PR inhibitors. Two of the most active compounds, VRX-480773 and GW-678248, were also tested in primary human cells and mediated cytotoxicity on HIV-1 infected peripheral blood mononuclear cells. Conclusion These data present proof of concept for targeted drug induced elimination of HIV producing cells. While NNRTIs themselves may not be sufficiently potent for therapeutic application, the results provide a basis for the development of drugs exploiting this mechanism of action.
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Affiliation(s)
- Dirk Jochmans
- Department of Infectious Diseases, Virology, University of Heidelberg, Germany
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Abstract
BACKGROUND INFORMATION Cell fusion is known to underlie key developmental processes in humans and is postulated to contribute to tissue maintenance and even carcinogenesis. The mechanistic details of cell fusion, especially between different cell types, have been difficult to characterize because of the dynamic nature of the process and inadequate means to track fusion products over time. Here we introduce an inducible system for detecting and tracking live cell fusion products in vitro and potentially in vivo. This system is based on BiFC (bimolecular fluorescence complementation) analysis. In this approach, two proteins that can interact with each other are joined to fragments of a fluorescent protein and are expressed in separate cells. The interaction of said proteins after cell fusion produces a fluorescent signal, enabling the identification and tracking of fusion products over time. RESULTS Long-term tracking of fused p53-deficient cells revealed that hybrid cells were capable of proliferation. In some cases, proliferation was preceded by nuclear fusion and division was asymmetric (69%+/-2% of proliferating hybrids), suggesting chromosomal instability. In addition, asymmetric division following proliferation could give rise to progeny indistinguishable from unfused counterparts. CONCLUSIONS These results support the possibility that the chromosomal instability characteristic of tumour cells may be incurred as a consequence of cell fusion and suggest that the role of cell fusion in carcinogenesis may have been masked to this point for lack of an inducible method to track cell fusion. In sum, the BiFC-based approach described here allows for comprehensive studies of the mechanism and biological impact of cell fusion in nature.
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Makki R, Meister M, Pennetier D, Ubeda JM, Braun A, Daburon V, Krzemień J, Bourbon HM, Zhou R, Vincent A, Crozatier M. A short receptor downregulates JAK/STAT signalling to control the Drosophila cellular immune response. PLoS Biol 2010; 8:e1000441. [PMID: 20689801 PMCID: PMC2914635 DOI: 10.1371/journal.pbio.1000441] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 06/17/2010] [Indexed: 12/31/2022] Open
Abstract
Regulation of JAK/STAT signalling by a short, nonsignalling receptor in Drosophila modulates response to specific immune challenges such as parasitoid infestations. The posterior signalling centre (PSC), a small group of specialised cells, controls hemocyte (blood cell) homeostasis in the Drosophila larval hematopoietic organ, the lymph gland. This role of the PSC is very reminiscent of the “niche,” the micro-environment of hematopoietic stem cells in vertebrates. We have recently shown that the PSC acts in a non–cell-autonomous manner to maintain janus tyrosine kinase/signal transducers and activators of transcription (JAK/STAT) signalling in hematopoietic progenitors (prohemocytes), thereby preserving the multipotent character necessary for their differentiation into lamellocytes, a cryptic and dedicated immune cell type required to fight specific immune threats such as wasp parasitism. In this report, on the basis of a knock out generated by homologous recombination, we show that a short type I cytokine-related receptor CG14225/Latran is required for switching off JAK/STAT signalling in prohemocytes. This is a prerequisite to massive differentiation of lamellocytes upon wasp parasitisation. In vivo and cell culture assays indicate that Latran forms heteromers with Domeless, the Drosophila type I cytokine signalling receptor related to mammalian GP130, and antagonises Domeless activity in a dose-dependent manner. Our analysis further shows that a primary immune response to wasp parasitism is a strong decrease in cytokine mRNA levels in the lymph gland, followed by an increase in the latran/domeless ratio. We propose that this sequence of events culminates in the complete inhibition of residual JAK/STAT signalling by Latran. JAK/STAT activity has been associated with several human diseases including leukaemia while knock-out studies in mice point to a central role of this pathway in hematopoiesis and regulation of immune functions. The specific function of Drosophila Latran is, to our knowledge, the first in vivo example of a role for a nonsignalling receptor in controlling a dedicated immune response, and thus raises the question of whether short, nonsignalling receptors also control specific aspects of vertebrate cellular immunity. A specific microenvironment termed the “niche” supports long term maintenance of hematopoietic stem cells in vertebrates. A small group of specialised cells called the posterior signalling center (PSC) controls hemocyte (blood cell) homeostasis in the Drosophila larval hematopoietic tissue and thus fulfills a similar function to the vertebrate niche. The PSC acts at a distance to maintain JAK/STAT signalling in hematopoietic progenitors (prohemocytes), thereby ensuring their multipotent character. We report here that a short cytokine receptor encoded by CG14225/latran is required to extinguish JAK/STAT signalling in prohemocytes and thereby ensures their mass differentiation into lamellocytes, an immune cell type required to fight specific threats such as wasp parasitism. Domeless, a related receptor in Drosophila, was previously the only known cytokine receptor that signals through the JAK/STAT pathway. We show that Latran lacks the intracellular domains required for signal transduction and acts instead by antagonizing the function of Domeless in a dose-dependent manner. The role of Drosophila Latran in the repression of JAK/STAT signalling under specific immune conditions raises the question of whether short, nonsignalling receptors that antagonize full-length receptors could also control specific aspects of vertebrate immunity.
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Affiliation(s)
- Rami Makki
- Université Toulouse 3, Toulouse, France
- Centre de Biologie du Développement UMR5547 CNRS Toulouse, France
| | - Marie Meister
- Institut de Biologie Moléculaire et Cellulaire, UPR9022 CNRS, Strasbourg, France
| | - Delphine Pennetier
- Université Toulouse 3, Toulouse, France
- Centre de Biologie du Développement UMR5547 CNRS Toulouse, France
| | - Jean-Michel Ubeda
- Institut de Biologie Moléculaire et Cellulaire, UPR9022 CNRS, Strasbourg, France
| | - Anne Braun
- Institut de Biologie Moléculaire et Cellulaire, UPR9022 CNRS, Strasbourg, France
| | - Virginie Daburon
- Université Toulouse 3, Toulouse, France
- Centre de Biologie du Développement UMR5547 CNRS Toulouse, France
| | - Joanna Krzemień
- Université Toulouse 3, Toulouse, France
- Centre de Biologie du Développement UMR5547 CNRS Toulouse, France
| | - Henri-Marc Bourbon
- Université Toulouse 3, Toulouse, France
- Centre de Biologie du Développement UMR5547 CNRS Toulouse, France
| | - Rui Zhou
- Department of Genetics at Harvard Medical School, Boston, Massachusetts, United States of America
| | - Alain Vincent
- Université Toulouse 3, Toulouse, France
- Centre de Biologie du Développement UMR5547 CNRS Toulouse, France
- * E-mail: (AV); (MC)
| | - Michèle Crozatier
- Université Toulouse 3, Toulouse, France
- Centre de Biologie du Développement UMR5547 CNRS Toulouse, France
- * E-mail: (AV); (MC)
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17
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Gonçalves MAFV, Janssen JM, Holkers M, de Vries AAF. Rapid and sensitive lentivirus vector-based conditional gene expression assay to monitor and quantify cell fusion activity. PLoS One 2010; 5:e10954. [PMID: 20532169 PMCID: PMC2880594 DOI: 10.1371/journal.pone.0010954] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Accepted: 05/12/2010] [Indexed: 11/18/2022] Open
Abstract
Cell-to-cell fusion is involved in multiple fundamental biological processes. Prominent examples include osteoclast and giant cell formation, fertilization and skeletal myogenesis which involve macrophage, sperm-egg and myoblast fusion, respectively. Indeed, the importance of cell fusion is underscored by the wide range of homeostatic as well as pathologic processes in which it plays a key role. Therefore, rapid and sensitive systems to trace and measure cell fusion events in various experimental systems are in demand. Here, we introduce a bipartite cell fusion monitoring system based on a genetic switch responsive to the site-specific recombinase FLP. To allow flexible deployment in both dividing as well as non-dividing cell populations, inducer and reporter modules were incorporated in lentivirus vector particles. Moreover, the recombinase-inducible transcription units were designed in such a way as to minimize basal activity and chromosomal position effects in the "off" and "on" states, respectively. The lentivirus vector-based conditional gene expression assay was validated in primary human mesenchymal stem cells and in a differentiation model based on muscle progenitor cells from a Duchenne muscular dystrophy patient using reporter genes compatible with live- and single-cell imaging and with whole population measurements. Using the skeletal muscle cell differentiation model, we showed that the new assay displays low background activity, a 2-log dynamic range, high sensitivity and is amenable to the investigation of cell fusion kinetics. The utility of the bipartite cell fusion monitoring system was underscored by a study on the impact of drug- and RNAi-mediated p38 MAPK inhibition on human myocyte differentiation. Finally, building on the capacity of lentivirus vectors to readily generate transgenic animals the present FLP-inducible system should be adaptable, alone or together with Cre/loxP-based assays, to cell lineage tracing and conditional gene manipulation studies in vivo.
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Affiliation(s)
- Manuel A F V Gonçalves
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
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18
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Grote E. Secretion is required for late events in the cell-fusion pathway of mating yeast. J Cell Sci 2010; 123:1902-12. [PMID: 20460435 DOI: 10.1242/jcs.066662] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Secretory vesicles accumulate adjacent to the contact site between the two cells of a yeast mating pair before they fuse, but there is no direct evidence that secretion is required to complete fusion. In this study, temperature-sensitive secretion (sec(ts)) mutants were used to investigate the role of secretion in yeast cell fusion. Cell fusion arrested less than 5 minutes after inhibiting secretion. This rapid fusion arrest was not an indirect consequence of reduced mating pheromone signaling, mating-pair assembly or actin polarity. Furthermore, secretion was required to complete cell fusion when it was transiently inhibited by addition and removal of the lipophilic styryl dye, FM4-64. These results indicate that ongoing secretion is required for late events in the cell-fusion pathway, which include plasma-membrane fusion and the completion of cell-wall remodeling, and they demonstrate a just-in-time delivery mechanism for the cell-fusion machinery.
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Affiliation(s)
- Eric Grote
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205.
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19
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Broome AM, Bhavsar N, Ramamurthy G, Newton G, Basilion JP. Expanding the utility of beta-galactosidase complementation: piece by piece. Mol Pharm 2010; 7:60-74. [PMID: 19899815 PMCID: PMC2835542 DOI: 10.1021/mp900188e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability to image and quantify multiple biomarkers in disease necessitates the development of split reporter fragment platforms. We have divided the beta-galactosidase enzyme into unique, independent polypeptides that are able to reassemble and complement enzymatic activity in bacteria and in mammalian cells. We created two sets of complementing pairs that individually have no enzymatic activity. However, when brought into close geometric proximity, the complementing pairs associated resulting in detectable enzymatic activity. We then constructed a stable ligand complex composed of reporter fragment, linker, and targeting moiety. The targeting moiety, in this case a ligand, allowed cell surface receptor targeting in vitro. Further, we were able to simultaneously visualize two cell surface receptors implicated in cancer development, epidermal growth factor receptor and transferrin receptor, using complementing pairs of the ligand-reporter fragment complex.
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Affiliation(s)
- Ann-Marie Broome
- Department of Biomedical Engineering, Case Center for Imaging Research and National Foundation for Cancer Research Center for Molecular Imaging, Case Western Reserve University
- Department of Radiology, Case Center for Imaging Research and National Foundation for Cancer Research Center for Molecular Imaging, Case Western Reserve University
- Department of Dermatology, Case Western Reserve University
| | - Nihir Bhavsar
- Department of Biomedical Engineering, Case Center for Imaging Research and National Foundation for Cancer Research Center for Molecular Imaging, Case Western Reserve University
| | - Gopal Ramamurthy
- Department of Radiology, Case Center for Imaging Research and National Foundation for Cancer Research Center for Molecular Imaging, Case Western Reserve University
| | - Gail Newton
- Department of Pathology at Harvard Medical School, Brigham and Women’s Hospital, Boston, Massachusetts
| | - James P. Basilion
- Department of Biomedical Engineering, Case Center for Imaging Research and National Foundation for Cancer Research Center for Molecular Imaging, Case Western Reserve University
- Department of Radiology, Case Center for Imaging Research and National Foundation for Cancer Research Center for Molecular Imaging, Case Western Reserve University
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20
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Abstract
Indoxyl esters and glycosides are useful chromogenic substrates for detecting enzyme activities in histochemistry, biochemistry and bacteriology. The chemical reactions exploited in the laboratory are similar to those that generate indigoid dyes from indoxyl-beta-d-glucoside and isatans (in certain plants), indoxyl sulfate (in urine), and 6-bromo-2-S-methylindoxyl sulfate (in certain molluscs). Pairs of indoxyl molecules released from these precursors react rapidly with oxygen to yield insoluble blue indigo (or purple 6,6'-dibromoindigo) and smaller amounts of other indigoid dyes. Our understanding of indigogenic substrates was developed from studies of the hydrolysis of variously substituted indoxyl acetates for use in enzyme histochemistry. The smallest dye particles, with least diffusion from the sites of hydrolysis, are obtained from 5-bromo-, 5-bromo-6-chloro- and 5-bromo-4-chloroindoxyl acetates, especially the last of these three. Oxidation of the diffusible indoxyls to insoluble indigoid dyes must occur rapidly. This is achieved with atmospheric oxygen and an equimolar mixture of K(3)Fe(CN)(6) and K(4)Fe(CN)(6), which has a catalytic function. H(2)O(2) is a by-product of the oxidation of indoxyl by oxygen. In the absence of a catalyst, the indoxyl diffuses and is oxidized by H(2)O(2) (catalyzed by peroxidase-like proteins) in sites different from those of the esterase activity. The concentration of K(3)Fe(CN)(6)/K(4)Fe(CN)(6) in a histochemical medium should be as low as possible because this mixture inhibits some enzymes and also promotes parallel formation from the indoxyl of soluble yellow oxidation products. The identities and positions of halogen substituents in the indoxyl moiety of a substrate determine the color and the physical properties of the resulting indigoid dye. The principles of indigogenic histochemistry learned from the study of esterases are applicable to methods for localization of other enzymes, because all indoxyl substrates release the same type of chromogenic product. Substrates are commercially available for a wide range of carboxylic esterases, phosphatases, phosphodiesterases, aryl sulfatase and several glycosidases. Indigogenic methods for carboxylic esterases have low substrate specificity and are used in conjunction with specific inhibitors of different enzymes of the group. Indigogenic methods for acid and alkaline phosphatases, phosphodiesterases and aryl sulfatase generally have been unsatisfactory; other histochemical techniques are preferred for these enzymes. Indigogenic methods are widely used, however, for glycosidases. The technique for beta-galactosidase activity, using 5-bromo-4-chloroindoxyl-beta-galactoside (X-gal) is applied to microbial cultures, cell cultures and tissues that contain the reporter gene lac-z derived from E. coli. This bacterial enzyme has a higher pH optimum than the lysosomal beta-galactosidase of animal cells. In plants, the preferred reporter gene is gus, which encodes beta-glucuronidase activity and is also demonstrable by indigogenic histochemistry. Indoxyl substrates also are used to localize enzyme activities in non-indigogenic techniques. In indoxyl-azo methods, the released indoxyl couples with a diazonium salt to form an azo dye. In indoxyl-tetrazolium methods, the oxidizing agent is a tetrazolium salt, which is reduced by the indoxyl to an insoluble coloured formazan. Indoxyl-tetrazolium methods operate only at high pH; the method for alkaline phosphatase is used extensively to detect this enzyme as a label in immunohistochemistry and in Western blots. The insolubility of indigoid dyes in water limits the use of indigogenic substrates in biochemical assays for enzymes, but the intermediate indoxyl and leucoindigo compounds are strongly fluorescent, and this property is exploited in a variety of sensitive assays for hydrolases. The most commonly used substrates for this purpose are glycosides and carboxylic and phosphate esters of N-methylindoxyl. Indigogenic enzyme substrates are among many chromogenic reagents used to facilitate the identification of cultured bacteria. An indoxyl substrate must be transported into the organisms by a permease to detect intracellular enzymes, as in the blue/white test for recognizing E. coli colonies that do or do not express the lac-z gene. Secreted enzymes are detected by substrate-impregnated disks or strips applied to the surfaces of cultures. Such devices often include several reagents, including indigogenic substrates for esterases, glycosidases and DNAse.
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Affiliation(s)
- J A Kiernan
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada.
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21
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Rahib L, Sriram G, Harada MK, Liao JC, Dipple KM. Transcriptomic and network component analysis of glycerol kinase in skeletal muscle using a mouse model of glycerol kinase deficiency. Mol Genet Metab 2009; 96:106-12. [PMID: 19121967 PMCID: PMC2702540 DOI: 10.1016/j.ymgme.2008.11.163] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 11/16/2008] [Accepted: 11/16/2008] [Indexed: 11/25/2022]
Abstract
Glycerol kinase (GK) is at the interface of fat and carbohydrate metabolism and has been linked to obesity and type 2 diabetes mellitus (T2DM). The purpose of this study was to investigate the role of GK in fat metabolism and insulin signaling in skeletal muscle (an important end organ tissue in T2DM). Microarray analysis determined that there were 525 genes that were differentially expressed (1.2-fold, p value<0.05) between knockout (KO) and wild-type (WT) mice. Quantitative PCR (qPCR) confirmed the differential expression of genes including glycerol kinase (Gyk), phosphatidylinositol 3-kinase regulatory subunit, polypeptide 1 (p85 alpha) (Pik3r1), insulin-like growth factor 1 (Igf1), and growth factor receptor bound protein 2-associated protein 1 (Gab1). Network component analysis demonstrated that transcription factor activities of myogenic differentiation 1 (MYOD), myogenic regulatory factor 5 (MYF5), myogenin (MYOG), nuclear receptor subfamily 4, group A, member 1 (NUR77) are decreased in the Gyk KO whereas the activity of paired box 3 (PAX3) is increased. The activity of MYOD was confirmed using a DNA binding assay. In addition, myoblasts from Gyk KO had less ability to differentiate into myotubes compared to WT myoblasts. These findings support our previous studies in brown adipose tissue and demonstrate that the role of Gyk in muscle is due in part to its non-metabolic (moonlighting) activities.
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MESH Headings
- Animals
- Cell Differentiation
- Cells, Cultured
- Diabetes Mellitus, Type 2/enzymology
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Disease Models, Animal
- Female
- Gene Expression Profiling
- Gene Regulatory Networks
- Glycerol Kinase/deficiency
- Glycerol Kinase/genetics
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/enzymology
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Protein Binding
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Affiliation(s)
- Lola Rahib
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
| | - Ganesh Sriram
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA, USA
| | - Melissa K. Harada
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
| | - James C. Liao
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA, USA
| | - Katrina M. Dipple
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Mattel Children’s Hospital at UCLA, University of California, Los Angeles, CA, USA
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22
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Richard JP, Leikina E, Chernomordik LV. Cytoskeleton reorganization in influenza hemagglutinin-initiated syncytium formation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:450-7. [PMID: 18976631 DOI: 10.1016/j.bbamem.2008.09.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 09/23/2008] [Accepted: 09/24/2008] [Indexed: 11/28/2022]
Abstract
Little is known about the mechanisms of cell-cell fusion in development and diseases and, especially, about fusion stages downstream of an opening of nascent fusion pore(s). Earlier works on different cell-cell fusion reactions have indicated that cytoskeleton plays important role in syncytium formation. However, due to complexity of these reactions and multifaceted contributions of cytoskeleton in cell physiology, it has remained unclear whether cytoskeleton directly drives fusion pore expansion or affects preceding fusion stages. Here we explore cellular reorganization associated with fusion pore expansion in syncytium formation using relatively simple experimental system. Fusion between murine embryonic fibroblasts NIH3T3-based cells is initiated on demand by well-characterized fusogen influenza virus hemagglutinin. We uncouple early fusion stages dependent on protein fusogens from subsequent fusion pore expansion stage and establish that the transition from local fusion to syncytium requires metabolic activity of living cells. Effective syncytium formation for cells with disorganized actin and microtubule cytoskeleton argues against hypothesis that cytoskeleton drives fusion expansion.
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Affiliation(s)
- Jean-Philippe Richard
- Section on Membrane Biology, Laboratory of Cellular and Molecular Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
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23
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Ding H, Johnson GVW. New application of beta-galactosidase complementation to monitor tau self-association. J Neurochem 2008; 106:1545-51. [PMID: 18498442 DOI: 10.1111/j.1471-4159.2008.05496.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Neurofibrillary tangles composed of hyperphosphorylated and aberrantly cleaved microtubule-associated protein tau are a major neuropathological hallmark of Alzheimer's disease. Recent studies suggest that the predominant neurotoxic effect of pathologically processed tau is mediated by intermediate tau multimers rather than the mature tau tangles, thus underscoring the importance of studying tau self-association preceding tangle formation. However, experimental approaches for such studies are limited. Here, we describe a modification of the beta-galactosidase (beta-gal) complementation assay, which provides a simple, sensitive and quantitative system to monitor pre-tangle tau-tau interactions in a cell model. Full-length tau (T4) and tau truncated at D421 (C3, to mimic caspase-cleaved tau) were fused to one of a pair of weakly complementing beta-gal mutants (Deltaalpha and Deltaomega) and expressed in human embryonic kidney cells. The tau-tau interactions and the subsequent juxtapositioning of Deltaalpha and Deltaomega led to beta-gal complementation and an increase in beta-gal activity which was detected by histochemical staining and quantified by chemiluminescent assays. After cross-linking with disuccinimidyl suberate, tau formed high molecular weight complexes which were detected on denaturing acrylamide gels, further confirming the close proximity among self-associated tau molecules. The self-association of C3 appeared to be less efficient than that of T4. Furthermore, treatment with lithium decreased beta-gal complementation of both T4 and C3 indicating that the interaction of these proteins was attenuated. Overall, this study suggests that beta-gal complementation assay can be a useful tool to monitor tau self-association.
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Affiliation(s)
- Huiping Ding
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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24
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Yeast and mammalian two-hybrid systems for studying protein-protein interactions. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2008; 383:215-25. [PMID: 18217688 DOI: 10.1007/978-1-59745-335-6_14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
An important step in the analysis of protein function is identification of the interaction partners of each protein. The two-hybrid system has been widely used to identify and explore protein-protein interactions. By using various two-hybrid systems, numerous protein interactions that regulate apoptosis signaling have been discovered that reveal unexpected functions of cancer-relevant proteins. Methods for performing two-hybrid experiments using either yeast or mammalian cells will be described in this chapter.
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25
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Pajcini KV, Pomerantz JH, Alkan O, Doyonnas R, Blau HM. Myoblasts and macrophages share molecular components that contribute to cell-cell fusion. ACTA ACUST UNITED AC 2008; 180:1005-19. [PMID: 18332221 PMCID: PMC2265408 DOI: 10.1083/jcb.200707191] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cell–cell fusion is critical to the normal development of certain tissues, yet the nature and degree of conservation of the underlying molecular components remains largely unknown. Here we show that the two guanine-nucleotide exchange factors Brag2 and Dock180 have evolutionarily conserved functions in the fusion of mammalian myoblasts. Their effects on muscle cell formation are distinct and are a result of the activation of the GTPases ARF6 and Rac, respectively. Inhibition of ARF6 activity results in a lack of physical association between paxillin and β1-integrin, and disruption of paxillin transport to sites of focal adhesion. We show that fusion machinery is conserved among distinct cell types because Dock180 deficiency prevented fusion of macrophages and the formation of multinucleated giant cells. Our results are the first to demonstrate a role for a single protein in the fusion of two different cell types, and provide novel mechanistic insight into the function of GEFs in the morphological maturation of multinucleated cells.
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Affiliation(s)
- Kostandin V Pajcini
- Department of Microbiology & Immunology, Baxter Laboratory in Genetic Pharmacology, Stanford University School of Medicine, Stanford, CA 94305, USA
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26
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Abstract
Cell fusion would seem to be obviously recognizable upon visual inspection, and many studies employ a simple microscopic fusion index to quantify the rate and extent of fusion in cell culture. However, when cells are not in monolayers or when there is a large background of multinucleation through failed cytokinesis, cell-cell fusion can only be proven by mixing of cell contents. Furthermore, determination of the microscopic fusion index must generally be carried out manually, creating opportunities for unintended observer bias and limiting the numbers of cells assayed and therefore the statistical power of the assay. Strategies for making assays dependent on fusion and independent of visual observation are critical to increasing the accuracy and throughput of screens for molecules that control cell fusion. A variety of in vitro biochemical and nonbiochemical techniques have been developed to assay and monitor fusion events in cultured cells. In this chapter, we briefly discuss several in vitro fusion assays, nearly all based on systems of two components that interact to create a novel assayable signal only after cells fuse. We provide details for the use of one example of such a system, intracistronic complementation of beta-galactosidase activity by mutants of Escherichia coli lacZ, which allows for either cell-by-cell microscopic assay of cell fusion or quantitative and kinetic detection of cell fusions in whole populations. In addition, we describe a combination of gene knock-down protocols with this assay to study factors required for myoblast fusion.
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Affiliation(s)
- Jessica H Shinn-Thomas
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT, USA
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27
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Hammer MM, Wehrman TS, Blau HM. A novel enzyme complementation-based assay for monitoring G-protein-coupled receptor internalization. FASEB J 2007; 21:3827-34. [PMID: 17942829 DOI: 10.1096/fj.07-8777com] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
G-protein-coupled receptor (GPCR) signaling is involved in a wide range of physiological processes and diseases, and around one-half of currently used drugs target GPCRs. Assays for the signaling of GPCRs have suffered from drawbacks, including low signal-to-noise, temporally transient signals, and difficulty in applying a single assay to a wide range of GPCRs. We have developed a set of assays for G-protein-coupled receptor signaling based on beta-galactosidase enzyme complementation in live mammalian cells. We previously described an assay for GPCR activation by monitoring the binding of beta-arrestin to the receptor. Here we describe a second assay that monitors the internalization of GPCRs to endosomes, an event that follows receptor activation and is critical in desensitizing and resensitizing the receptor. We show that both assays display high signal-to-noise ratios with low variability and are quantitative for a wide range of GPCRs. EC50s obtained with these assays closely match results reported in the literature. Finally, we show that these assays are readily adapted to high-throughput chemical screens. Thus, these two assays for monitoring G-protein-coupled receptor activation and internalization should prove valuable in basic biological studies as well as in high-throughput screens.
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Affiliation(s)
- Mark M Hammer
- Baxter Laboratory in Genetic Pharmacology, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305-5175, USA
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28
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Shoemaker BA, Panchenko AR. Deciphering protein-protein interactions. Part I. Experimental techniques and databases. PLoS Comput Biol 2007; 3:e42. [PMID: 17397251 PMCID: PMC1847991 DOI: 10.1371/journal.pcbi.0030042] [Citation(s) in RCA: 235] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Borloo J, De Smet L, Vergauwen B, Van Beeumen JJ, Devreese B. A β-Galactosidase-Based Bacterial Two-Hybrid System To Assess Protein−Protein Interactions in the Correct Cellular Environment. J Proteome Res 2007; 6:2587-95. [PMID: 17539672 DOI: 10.1021/pr070037j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The vast majority of proteins functions in complex with one or more of the same or other proteins, indicating that protein-protein interactions play crucial roles in biology. Here, we present a beta-galactosidase reconstitution-based bacterial two-hybrid system in which two proteins of interest are fused to two non-functional but complementing beta-galactosidase truncations (Delta alpha and Delta omega). The level of complemented beta-galactosidase activity, driven by the protein-protein recognition between both non-beta-galactosidase parts of the chimeras, reflects whether or not the proteins of interest interact. Our approach was validated by reconfirming some well-established Escherichia coli cytoplasmic and membranous interactions, including well-chosen mutants, and providing the first in vivo evidence for the transient periplasmic interaction between Rhodobacter capsulatus cytochrome c2 and cytochrome c peroxidase. We demonstrated the major advantages of this in vivo two-hybrid technique: i) analyses of interactions are not limited to particular cellular compartments, ii) the potential of using the system in mutation-driven structure-function studies, and iii) the possibility of its application to transiently interacting proteins. These benefits demonstrate the relevance of the method as a powerful new tool in the broad spectrum of interaction assessment methods.
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Affiliation(s)
- Jimmy Borloo
- Department of Biochemistry, Physiology and Microbiology, Ghent University, Laboratory for Protein Biochemistry and Protein Engineering, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium.
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30
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Olson KR, Eglen RM. Beta galactosidase complementation: a cell-based luminescent assay platform for drug discovery. Assay Drug Dev Technol 2007; 5:137-44. [PMID: 17355206 DOI: 10.1089/adt.2006.052] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Many cell-based assays interrogating cell pathway activation employ protocols that require microscopic imaging techniques. However, such assays are not in general widely adopted for primary screening. Protein complementation, particularly of enzymes, provides an alternative approach for cell pathway analysis, with a principal advantage that is amenable to high throughput screening using microtiter plate protocols. Notably, alpha complementation of the enzyme beta-galactosidase has been exploited as a technology in this regard, using substrates that generates luminescent signals. This review describes the various uses of this flexible technology to cell-based assay development.
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Karniely S, Rayzner A, Sass E, Pines O. Alpha-complementation as a probe for dual localization of mitochondrial proteins. Exp Cell Res 2006; 312:3835-46. [PMID: 17034789 DOI: 10.1016/j.yexcr.2006.08.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 08/12/2006] [Accepted: 08/15/2006] [Indexed: 11/23/2022]
Abstract
There are a growing number of proteins which are reported to reside in multiple compartments within the eukaryotic cell. However, lack of appropriate methods limits our knowledge on the true extent of this phenomenon. In this study, we demonstrate a novel application of beta-galactosidase alpha-complementation to study dual distribution of proteins in yeast cells. Using a simple colony color phenotype, we show that alpha-complementation depends on co-compartmentalization of alpha and omega fragments and exploit this to probe dual localization of proteins between the cytosol and mitochondria in yeast. The quality of our assay was assessed by analysis of the known dual targeted enzyme fumarase and several mutant derivatives, which are exclusively localized to one or the other of these subcellular compartments. Addition of the alpha fragment did not abolish the enzymatic activity of the tagged proteins nor did it affect their localization. By examining 10 yeast gene products for distribution between the cytosol and the mitochondria, we demonstrate the potential of alpha-complementation to screen the mitochondrial proteome for dual distribution. Our data indicate the distribution of two uncharacterized proteins--Bna3 and Nif3--between the cytosol and the mitochondria.
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Affiliation(s)
- Sharon Karniely
- Department of Molecular Biology, Hebrew University Medical School, Jerusalem 91120, Israel
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32
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Citovsky V, Lee LY, Vyas S, Glick E, Chen MH, Vainstein A, Gafni Y, Gelvin SB, Tzfira T. Subcellular localization of interacting proteins by bimolecular fluorescence complementation in planta. J Mol Biol 2006; 362:1120-31. [PMID: 16949607 DOI: 10.1016/j.jmb.2006.08.017] [Citation(s) in RCA: 282] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 08/03/2006] [Accepted: 08/03/2006] [Indexed: 11/18/2022]
Abstract
Bimolecular fluorescence complementation (BiFC) represents one of the most advanced and powerful tools for studying and visualizing protein-protein interactions in living cells. In this method, putative interacting protein partners are fused to complementary non-fluorescent fragments of an autofluorescent protein, such as the yellow spectral variant of the green fluorescent protein. Interaction of the test proteins may result in reconstruction of fluorescence if the two portions of yellow spectral variant of the green fluorescent protein are brought together in such a way that they can fold properly. BiFC provides an assay for detection of protein-protein interactions, and for the subcellular localization of the interacting protein partners. To facilitate the application of BiFC to plant research, we designed a series of vectors for easy construction of N-terminal and C-terminal fusions of the target protein to the yellow spectral variant of the green fluorescent protein fragments. These vectors carry constitutive expression cassettes with an expanded multi-cloning site. In addition, these vectors facilitate the assembly of BiFC expression cassettes into Agrobacterium multi-gene expression binary plasmids for co-expression of interacting partners and additional autofluorescent proteins that may serve as internal transformation controls and markers of subcellular compartments. We demonstrate the utility of these vectors for the analysis of specific protein-protein interactions in various cellular compartments, including the nucleus, plasmodesmata, and chloroplasts of different plant species and cell types.
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Affiliation(s)
- Vitaly Citovsky
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, USA
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33
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Conclusions. Proteomics 2005. [DOI: 10.1007/0-306-46895-6_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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34
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Wehrman TS, Casipit CL, Gewertz NM, Blau HM. Enzymatic detection of protein translocation. Nat Methods 2005; 2:521-7. [PMID: 15973423 DOI: 10.1038/nmeth771] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Accepted: 05/23/2005] [Indexed: 11/09/2022]
Abstract
Fundamental to eukaryotic cell signaling is the regulation of protein function by directed localization. Detection of these events has been largely qualitative owing to the limitations of existing technologies. Here we describe a method for quantitatively assessing protein translocation using proximity-induced enzyme complementation. The complementation assay for protein translocation (CAPT) is derived from beta-galactosidase and comprises one enzyme fragment, omega, which is localized to a particular subcellular region, and a small complementing peptide, alpha, which is fused to the protein of interest. The concentration of alpha in the immediate vicinity of omega correlates with the amount of enzyme activity obtained in a dose- and time-dependent manner, thus acting as a genetically encoded biosensor for local protein concentration. Using CAPT, inducible protein movement from the cytosol to the nucleus or plasma membrane was quantitatively monitored in multiwell format and in live mammalian cells by flow cytometry.
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Affiliation(s)
- Tom S Wehrman
- Baxter Laboratory for Genetic Pharmacology, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305, USA
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35
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Rothman A, Feinstein P, Hirota J, Mombaerts P. The promoter of the mouse odorant receptor gene M71. Mol Cell Neurosci 2005; 28:535-46. [PMID: 15737743 DOI: 10.1016/j.mcn.2004.11.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 11/10/2004] [Accepted: 11/11/2004] [Indexed: 11/22/2022] Open
Abstract
From a repertoire of approximately 2000 odorant receptor (OR) alleles in the mouse genome, a mature olfactory sensory neuron (OSN) is thought to choose only one functional allele of one OR gene for expression. OSNs that express a given OR gene are scattered throughout an epithelial region that is gene specific. The DNA sequences that enable OR gene choice and specify the epithelial pattern are not known. Within the upstream regions of several mouse, rat, and human OR genes, we have previously recognized putative homeodomain and O/E-like binding sites in proximity to each other. Here, we define a minimal promoter region for expression of the mouse OR gene M71 with small transgenes. This region contains a homeodomain and an O/E-like binding site. Combined mutations in both sites abolish transgene expression. When identical mutations are introduced at the endogenous M71 locus by gene targeting, the number of M71-expressing OSNs is reduced by a factor of three and the epithelial pattern is ventralized. The stronger impact observed with the mutant transgenes compared to the targeted mutations may reflect a multiplicity of regulatory sites within the OR gene cluster. We propose that these homeodomain and O/E sites regulate the probability of M71 gene choice differentially across the olfactory epithelium.
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Affiliation(s)
- Andrea Rothman
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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36
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Carter AA, Hill SJ. Characterization of Isoprenaline- and Salmeterol-Stimulated Interactions between β2-Adrenoceptors and β-Arrestin 2 Using β-Galactosidase Complementation in C2C12 Cells. J Pharmacol Exp Ther 2005; 315:839-48. [PMID: 16051698 DOI: 10.1124/jpet.105.088914] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
beta-Arrestin is an adaptor protein that has been shown to couple G protein-coupled receptors (GPCRs) to clathrin-coated pits and target them for subsequent internalization. More recently, beta-arrestin 2 has also been shown to be involved in the activation of mitogen-activated protein kinase cascades by G protein-coupled receptors independently of G protein activation. Direct interactions between proteins can be monitored using enzyme complementation between two inactive deletion mutants of beta-galactosidase (beta-gal; Deltaalpha and Deltaomega). In the present study, we have used fusion proteins of the human beta(2)-adrenoceptor (C-terminal beta-gal Deltaalpha) and beta-arrestin 2 (beta-gal Deltaomega) to study directly the pharmacology of this interaction in C2C12 cells expressing the beta(2)-adrenoceptor-beta-gal Deltaalpha fusion protein at low physiological levels (38.2 +/- 2.7 fmol . mg protein(-1)). Isoprenaline, noradrenaline, and adrenaline (-log EC(50) = 5.9, 5.5, and 5.7, respectively) stimulated an association between the beta(2)-adrenoceptor and beta-arrestin 2 at much higher concentrations than required for activation of cAMP accumulation (-log EC(50) = 7.6, 6.3, and 7.7, respectively). This was sensitive to inhibition by the beta(2)-adrenoceptor antagonists propranolol, timolol, and ICI 118551. Both salbutamol and terbutaline behaved as partial agonists of beta-gal complementation. Furthermore, the long-acting beta(2)-agonist salmeterol (-log K(D) for inhibition of [(3)H]CGP12177 binding = 8.7) behaved as an antagonist of isoprenaline-stimulated beta(2)-adrenoceptor-arrestin 2 interactions (-log K(D) = 8.0), whereas acting as a full agonist of cAMP accumulation in the same cells (-log EC(50) = 9.2). These data suggest that salmeterol can discriminate between receptor-G(S) protein and receptor-arrestin 2 complexes (in terms of efficacy and affinity) in a way that is favorable for its long duration of action.
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Affiliation(s)
- Alison A Carter
- Institute of Cell Signaling, Medical School, Queen's Medical Centre, Nottingham, UK
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37
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Mitchell PO, Mills T, O'Connor RS, Kline ER, Graubert T, Dzierzak E, Pavlath GK. Sca-1 negatively regulates proliferation and differentiation of muscle cells. Dev Biol 2005; 283:240-52. [PMID: 15901485 DOI: 10.1016/j.ydbio.2005.04.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Revised: 03/12/2005] [Accepted: 04/15/2005] [Indexed: 10/25/2022]
Abstract
Satellite cells are tissue-specific stem cells critical for skeletal muscle growth and regeneration. Upon exposure to appropriate stimuli, satellite cells produce progeny myoblasts. Heterogeneity within a population of myoblasts ensures that a subset of myoblasts readily differentiate to form myotubes, whereas other myoblasts remain undifferentiated and thus available for future muscle growth. The mechanisms that contribute to this heterogeneity in myoblasts are largely unknown. We show that satellite cells are Sca-1(neg) but give rise to myoblasts that are heterogeneous for sca-1 expression. The majority of myoblasts are sca-1(neg), rapidly divide, and are capable of undergoing myogenic differentiation to form myotubes. In contrast, a minority population is sca-1(pos), divides slower, and does not readily form myotubes. Sca-1 expression is not static but rather dynamically modulated by the microenvironment. Gain-of-function and loss-of-function experiments demonstrate that sca-1 has a functional role in regulating proliferation and differentiation of myoblasts. Myofiber size of sca-1 null muscles is altered in an age-dependent manner, with increased size observed in younger mice and decreased size in older mice. These studies reveal a novel system that reversibly modulates the myogenic behavior of myoblasts. These studies provide evidence that, rather than being a fixed property, myoblast heterogeneity can be modulated by the microenvironment.
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Affiliation(s)
- Patrick O Mitchell
- Department of Pharmacology, Emory University School of Medicine, O. W. Rollins Research Center, Atlanta, GA 30322, USA
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38
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Abstract
Stem cell transdifferentiation in the adult organism is the most common and questioned mechanism of growth and repair. Recent data suggest that adult stem cells are capable of generating mature cells beyond their own tissue boundaries, a process called developmental plasticity. To date, the most versatile cell discovered is the bone marrow progenitor cell.
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Affiliation(s)
- Annarosa Leri
- Cardiovascular Research Institute, Department of Medicine, New York Medical College, Valhalla, New York.
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39
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Ball JC, Puckett LG, Bachas LG. Covalent immobilization of beta-galactosidase onto a gold-coated magnetoelastic transducer via a self-assembled monolayer: toward a magnetoelastic biosensor. Anal Chem 2004; 75:6932-7. [PMID: 14670055 DOI: 10.1021/ac0347866] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The enzyme beta-galactosidase has been covalently immobilized onto a gold-coated magnetoelastic film via a self-assembled monolayer (SAM) of omega-carboxylic acid alkylthiol. Use of magnetoelastic transduction allows for the wireless monitoring of enzymatic activity through the associated change in the frequency and amplitude of magnetic fields. The formations of SAMs of 3-mercaptopropanoic acid and thioctic acid were monitored by magnetoelastic transduction. After coupling of beta-galactosidase to the SAMs, the enzyme activity was monitored by using a substrate that forms an insoluble product upon action of the enzyme. Specifically, an indolyl galactopyranoside substrate was employed in conjunction with an azo dye as the precipitating system. The immobilized enzyme was evaluated and found to have an apparent Michaelis-Menten constant (KM) of 1.2 mM for the indolyl galactopyranoside. Calibration plots for both substrates and inhibitors were generated to establish the versatility of this sensing system. Kinetic parameters for nonprecipitating substrates were determined in conjunction with a precipitating enzymatic substrate by way of a competitive inhibition study using beta-galactosidase attached to magnetoelastic strips. The methods developed within this work allow for the fabrication of wireless enzyme sensing systems, which can also be used as another means of screening for enzyme inhibitors.
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Affiliation(s)
- J Christopher Ball
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA
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40
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Kondo T, Ikeda K, Matsuo K. Detection of osteoclastic cell-cell fusion through retroviral vector packaging. Bone 2004; 35:1120-6. [PMID: 15542037 DOI: 10.1016/j.bone.2004.06.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 06/14/2004] [Accepted: 06/17/2004] [Indexed: 11/18/2022]
Abstract
Cell-cell fusion generates multinucleated cells such as osteoclasts in bone, myotubes in muscle, and trophoblasts in placenta. Molecular details governing these fusion processes are still largely unknown. As a step toward identification of fusogenic genes, we tested the concept that retroviral vectors can be packaged as a result of cell-cell fusion. First, we introduced replication-deficient retroviral vectors expressing mCAT-1, which mediates fusogenic interaction with the retroviral envelope protein Env, into Chinese hamster ovary (CHO) cells to generate vector cells. Plasmids expressing virion proteins Gag, Pol, and Env were introduced into a separate culture of CHO cells to generate packaging cells. Co-culturing vector and packaging cells resulted in production of infectious retroviruses carrying the mCAT-1 gene as a consequence of cell-cell fusion. Second, we introduced a retroviral vector into primary osteoclast precursors and co-cultured them with established osteoclast precursor RAW264.7 cells, which turned out to harbor packaging activity. Packaged retroviral vector was detected in culture supernatants only where the osteoclast differentiation factor receptor activator for NF-kappaB ligand (RANKL) induced fusion between these two cell types. These data suggest that retrovirus production can occur as a result of cell-cell fusion. This provides a novel approach for isolating and characterizing fusogenic genes using retroviral expression vectors.
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Affiliation(s)
- Takako Kondo
- Department of Geriatric Research, National Institute for Longevity Sciences (NILS), Aichi 474-8522, Japan
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41
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Causier B. Studying the interactome with the yeast two-hybrid system and mass spectrometry. MASS SPECTROMETRY REVIEWS 2004; 23:350-367. [PMID: 15264234 DOI: 10.1002/mas.10080] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Protein interactions are crucial to the life of a cell. The analysis of such interactions is allowing biologists to determine the function of uncharacterized proteins and the genes that encode them. The yeast two-hybrid system has become one of the most popular and powerful tools to study protein-protein interactions. With the advent of proteomics, the two-hybrid system has found a niche in interactome mapping. However, it is clear that only by combining two-hybrid data with that from complementary approaches such as mass spectrometry (MS) can the interactome be analyzed in full. This review introduces the yeast two-hybrid system to those unfamiliar with the technique, and discusses how it can be used in combination with MS to unravel the network of protein interactions that occur in a cell.
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Affiliation(s)
- Barry Causier
- School of Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
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42
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Feinstein P, Mombaerts P. A contextual model for axonal sorting into glomeruli in the mouse olfactory system. Cell 2004; 117:817-31. [PMID: 15186781 DOI: 10.1016/j.cell.2004.05.011] [Citation(s) in RCA: 266] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Revised: 03/05/2004] [Accepted: 03/31/2004] [Indexed: 11/30/2022]
Abstract
No models fully account for how odorant receptors (ORs) function in the guidance of axons of olfactory sensory neurons (OSNs) to glomeruli in the olfactory bulb. Here, we use gene targeting in mice to demonstrate that the OR amino acid sequence imparts OSN axons with an identity that allows them to coalesce into glomeruli. Replacements between the coding regions of the M71 and M72 OR genes reroute axons to their respective glomeruli. A series of M71-M72 hybrid ORs uncover a spectrum of glomerular phenotypes, leading to the concept that the identity of OSN axons is revealed depending on what other axons are present. Naturally occurring amino acid polymorphisms in other ORs also produce distinct axonal identities. These critical amino acid residues are distributed throughout the protein and reside predominantly within transmembrane domains. We propose a contextual model for axon guidance in which ORs mediate homotypic interactions between like axons.
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Affiliation(s)
- Paul Feinstein
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
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43
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Yan YX, Boldt-Houle DM, Tillotson BP, Gee MA, D'Eon BJ, Chang XJ, Olesen CEM, Palmer MAJ. Cell-based high-throughput screening assay system for monitoring G protein-coupled receptor activation using beta-galactosidase enzyme complementation technology. ACTA ACUST UNITED AC 2003; 7:451-9. [PMID: 14599361 DOI: 10.1177/108705702237677] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A novel cell-based functional assay to directly monitor G protein-coupled receptor (GPCR) activation in a high-throughput format, based on a common GPCR regulation mechanism, the interaction between beta-arrestin and ligand-activated GPCR, is described. A protein-protein interaction technology, the InteraX trade mark system, uses a pair of inactive beta-galactosidase (beta-gal) deletion mutants as fusion partners to the protein targets of interest. To monitor GPCR activation, stable cell lines expressing both GPCR- and beta-arrestin-beta-gal fusion proteins are generated. Following ligand stimulation, beta-arrestin binds to the activated GPCR, and this interaction drives functional complementation of the beta-gal mutant fragments. GPCR activation is measured directly by quantitating restored beta-gal activity. The authors have validated this assay system with two functionally divergent GPCRs: the beta2-adrenergic amine receptor and the CXCR2 chemokine-binding receptor. Both receptors are activated or blocked with known agonists and antagonists in a dose-dependent manner. The beta2-adrenergic receptor cell line was screened with the LOPAC trade mark compound library to identify both agonists and antagonists, validating this system for high-throughput screening performance in a 96-well microplate format. Hit specificity was confirmed by quantitating the level of cAMP. This assay system has also been performed in a high-density (384-well) microplate format. This system provides a specific, sensitive, and robust methodology for studying and screening GPCR-mediated signaling pathways.
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MESH Headings
- Arrestins/genetics
- Arrestins/metabolism
- Biological Assay/instrumentation
- Biological Assay/methods
- Cells, Cultured
- Combinatorial Chemistry Techniques/methods
- Cyclic AMP/metabolism
- Dose-Response Relationship, Drug
- Drug Evaluation, Preclinical/instrumentation
- Drug Evaluation, Preclinical/methods
- Genes, erbB-1
- Humans
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- Protein Interaction Mapping/instrumentation
- Protein Interaction Mapping/methods
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Interleukin-8B/drug effects
- Receptors, Interleukin-8B/genetics
- Receptors, Interleukin-8B/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- beta-Galactosidase/genetics
- beta-Galactosidase/metabolism
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44
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Brown S, Hu N, Hombría JCG. Novel level of signalling control in the JAK/STAT pathway revealed by in situ visualisation of protein-protein interaction during Drosophila development. Development 2003; 130:3077-84. [PMID: 12783781 DOI: 10.1242/dev.00535] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
It is commonly accepted that activation of most signalling pathways is induced by ligand receptor dimerisation. This belief has been challenged for some vertebrate cytokine receptors of the JAK/STAT pathway. Here we study whether DOME, the Drosophila receptor of the JAK/STAT pathway, can dimerise and if the dimerisation is ligand-dependent. To analyse DOME homo-dimerisation, we have applied a beta-gal complementation technique that allows the detection of protein interactions in situ. This technique has been used previously in cell culture but this is the first time that it has been applied to whole embryos. We show that this technique, which we rename betalue-betalau technique, can be used to detect DOME homo-dimerisation in Drosophila developing embryos. Despite DOME being ubiquitously expressed, dimerisation is developmentally regulated. We investigate the state of DOME dimerisation in the presence or absence of ligand and show that DOME dimerisation is not ligand-induced, indicating that ligand independent cytokine receptor dimerisation is a conserved feature across phyla. We have further analysed the functional significance of ligand-independent receptor dimerisation by comparing the effects of ectopic ligand expression in cells in which the receptor is, or is not, dimerised. We show that ligand expression can only activate STAT downstream targets or affect embryo development in cells in which the receptor is dimerised. These results suggest a model in which ligand-independent dimerisation of the JAK/STAT receptor confers cells with competence to activate the pathway prior to ligand reception. Thus, competence to induce the JAK/STAT signalling pathway in Drosophila can be regulated by controlling receptor dimerisation prior to ligand binding. These results reveal a novel level of JAK/STAT signalling regulation that could also apply to vertebrates.
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Affiliation(s)
- Stephen Brown
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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45
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Abstract
Genomic research is expected to generate new types of complex observational data, changing the types of experiments as well as our understanding of biological processes. The investigation and definition of relationships among proteins is essential for understanding the function of each gene and the mechanisms of biological processes that specific genes are involved in. Recently, a study by Paulmurugan et al. demonstrated a tool for in vivo noninvasive imaging of protein-protein interactions and intracellular networks.
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Affiliation(s)
- Uwe Haberkorn
- Department of Nuclear Medicine, University of Heidelberg, Im Neuenheimer Feld 400, Heidelberg 69120, Germany.
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46
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Paulmurugan R, Umezawa Y, Gambhir SS. Noninvasive imaging of protein-protein interactions in living subjects by using reporter protein complementation and reconstitution strategies. Proc Natl Acad Sci U S A 2002; 99:15608-13. [PMID: 12438689 PMCID: PMC137764 DOI: 10.1073/pnas.242594299] [Citation(s) in RCA: 254] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this study we have developed bioluminescence-imaging strategies to noninvasively and quantitatively image protein-protein interactions in living mice by using a cooled charge-coupled device camera and split reporter technology. We validate both complementation and intein-mediated reconstitution of split firefly luciferase proteins driven by the interaction of two strongly interacting proteins, MyoD and Id. We use transient transfection of cells and image MyoD-Id interaction after induction of gene expression in cell culture and in cells implanted into living mice. Techniques to study protein-protein interactions in living subjects will allow the study of cellular networks, including signal transduction pathways, as well as development and optimization of pharmaceuticals for modulating protein-protein interactions.
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Affiliation(s)
- R Paulmurugan
- Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, University of California Los Angeles-Jonsson Comprehensive Cancer Center, 90095-1770, USA
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47
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Vassalli A, Rothman A, Feinstein P, Zapotocky M, Mombaerts P. Minigenes impart odorant receptor-specific axon guidance in the olfactory bulb. Neuron 2002; 35:681-96. [PMID: 12194868 DOI: 10.1016/s0896-6273(02)00793-6] [Citation(s) in RCA: 193] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
An olfactory sensory neuron (OSN) expresses selectively one member from a repertoire of approximately 1000 odorant receptor (OR) genes and projects its axon to a specific glomerulus in the olfactory bulb. Both processes are here recapitulated by MOR23 and M71 OR minigenes, introduced into mice. Minigenes of 9 kb and as short as 2.2 kb are selectively expressed by neurons that do not coexpress the endogenous gene but coproject their axons to the same glomeruli. Deletion of a 395 bp upstream region in the MOR23 minigene abolishes expression. In this region we recognize sequence motifs conserved in many OR genes. Transgenic lines expressing the OR in ectopic epithelial zones form ectopic glomeruli, which also receive input from OSNs expressing the cognate endogenous receptor. This suggests a recruitment through homotypic interactions between OSNs expressing the same OR.
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Affiliation(s)
- Anne Vassalli
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
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48
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Saito M, Hagita H, Ito M, Ando S, Yu RK. Age-dependent reduction in sialidase activity of nuclear membranes from mouse brain. Exp Gerontol 2002; 37:937-41. [PMID: 12086703 DOI: 10.1016/s0531-5565(02)00021-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sialidase is an enzyme that cleaves alpha-linked sialic acid residues from sialoglycoconjugates and participates in various cellular functions. In the present study, we characterized sialidase activity in nuclear membranes from mouse brain and examined its age-related changes. A highly purified nuclear membrane preparation from 4-week-old mouse brain contained sialidase activity that hydrolyzed both 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid (4MU-Neu5Ac) and ganglioside GM3. The specific activities directed toward both substrates were 6.33+/-0.77 and 13.4+/-1.1pmol/mgprotein/min, respectively. Nuclear localization of sialidase activity was confirmed by fluorescent cytochemistry of intact nuclei using 5-bromo-4-chloro-3-indolyl-alpha-D-N-acetylneuraminic acid (X-Neu5Ac) as the substrate. Age-related changes in nuclear sialidase activity in brain tissue were investigated using mice of different ages (i.e. 2-week-, 4-week-, 14-month-, and 26-month-old). Sialidase activity toward 4MU-Neu5Ac had almost identical levels at 2nd and 4th weeks, but thereafter decreased rapidly; the activity at 26 months was about one third of the young levels. Sialidase activity toward GM3 also showed a similar developmental pattern, though the reduction at advancing ages was less than that of activity toward 4MU-Neu5Ac. The present study demonstrates that the activity of nuclear sialidase decreases with aging. The reduced activity of nuclear sialidase may be implicated with alterations of neural cell function during aging.
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Affiliation(s)
- Megumi Saito
- Department of Clinical Pharmacology and Therapeutics, University of Shizuoka School of Pharmaceutical Sciences, 52-1 Yada, Japan.
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de Wildt RMT, Tomlinson IM, Ong JL, Holliger P. Isolation of receptor-ligand pairs by capture of long-lived multivalent interaction complexes. Proc Natl Acad Sci U S A 2002; 99:8530-5. [PMID: 12084913 PMCID: PMC124300 DOI: 10.1073/pnas.132008499] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We have combined phage display and array screening for the rapid isolation of pairs of interacting polypeptides. Our strategy, named SAC (selection by avidity capture), is based on the avidity effect, the formation of highly stable complexes formed by multivalent interactions; in our case, between a receptor (multivalently displayed on phage) and a ligand (coexpressed as a multimeric fusion protein). Capture of the long-lived interaction complex allows the isolation of phage bearing cognate interaction pairs, as we demonstrate for a range of interactions, including Ab-antigen pairs and the rapamycin-dependent interaction of FKBP-12 and FRAP. Cognate phage are enriched by SAC up to 1000-fold and interacting pairs can be identified by array screening. Application of SAC to Ab-antigen interactions as a model system yielded over 140 specific Abs to a single antigen and 92 Abs to three different fetal human brain antigens in a single round of SAC each. Our results suggest that SAC should prove useful for the identification and study of receptor-ligand interactions in particular among extracellular proteins, as well as for the rapid generation of specific Abs to multiple antigens.
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Affiliation(s)
- Ruud M T de Wildt
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom
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Yokozeki T, Ueda H, Arai R, Mahoney W, Nagamune T. A homogeneous noncompetitive immunoassay for the detection of small haptens. Anal Chem 2002; 74:2500-4. [PMID: 12069229 DOI: 10.1021/ac015743x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe a noncompetitive homogeneous immunoassay for small haptens based on the antigen-dependent reassociation of antibody variable domains and beta-galactosidase (beta-gal) complementation (open sandwich enzymatic complementation immunoassay). As a model system, the reassociation of two fusion proteins, an anti 4-hydroxy-3-nitrophenylacetyl (NP) antibody heavy-chain variable-region fragment fused to an N-terminal deletion mutant of beta-gal (V(H)delta alpha) and the light-chain variable-region fragment fused to a C-terminal deletion mutant of beta-gal (V(L)delta omega), was monitored by the enzymatic complementation between the two. Upon simple mixing of the reagents with the sample, an antigen (NP)-dependent increase in enzymatic activity was observed. When 5-iodo-NP was measured, a 10 times higher sensitivity was observed, probably due to its higher affinity. Compared with our corresponding heterogeneous open sandwich enzyme-linked immunosorbent assay, approximately 1000-fold improvement in the sensitivity was attained, probably due to lower background V(H)-V(L) association. In addition, the assay required less time, handling, sample volume, and assay reagents.
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Affiliation(s)
- Tomoichi Yokozeki
- Department of Chemistry and Biotechnology, School of Engineering, University of Tokyo, Japan
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