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Spiniello M, Steinbrink MI, Cesnik AJ, Miller RM, Scalf M, Shortreed MR, Smith LM. Comprehensive in vivo identification of the c-Myc mRNA protein interactome using HyPR-MS. RNA (NEW YORK, N.Y.) 2019; 25:1337-1352. [PMID: 31296583 PMCID: PMC6800478 DOI: 10.1261/rna.072157.119] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 06/27/2019] [Indexed: 05/10/2023]
Abstract
Proteins bind mRNA through their entire life cycle from transcription to degradation. We analyzed c-Myc mRNA protein interactors in vivo using the HyPR-MS method to capture the crosslinked mRNA by hybridization and then analyzed the bound proteins using mass spectrometry proteomics. Using HyPR-MS, 229 c-Myc mRNA-binding proteins were identified, confirming previously proposed interactors, suggesting new interactors, and providing information related to the roles and pathways known to involve c-Myc. We performed structural and functional analysis of these proteins and validated our findings with a combination of RIP-qPCR experiments, in vitro results released in past studies, publicly available RIP- and eCLIP-seq data, and results from software tools for predicting RNA-protein interactions.
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Affiliation(s)
- Michele Spiniello
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- Department of Medicine of Precision, University of Studi della Campania Luigi Vanvitelli, Naples 80138, Italy
- Division of Immuno-Hematology and Transfusion Medicine, Cardarelli Hospital, Naples 80131, Italy
| | - Maisie I Steinbrink
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Anthony J Cesnik
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Rachel M Miller
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Mark Scalf
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Michael R Shortreed
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Lloyd M Smith
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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2
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Steinberger J, Robert F, Hallé M, Williams DE, Cencic R, Sawhney N, Pelletier D, Williams P, Igarashi Y, Porco JA, Rodriguez AD, Kopp B, Bachmann B, Andersen RJ, Pelletier J. Tracing MYC Expression for Small Molecule Discovery. Cell Chem Biol 2019; 26:699-710.e6. [PMID: 30880156 DOI: 10.1016/j.chembiol.2019.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 12/19/2018] [Accepted: 02/07/2019] [Indexed: 12/16/2022]
Abstract
Our inability to effectively "drug" targets such as MYC for therapeutic purposes requires the development of new approaches. We report on the implementation of a phenotype-based assay for monitoring MYC expression in multiple myeloma cells. The open reading frame (ORF) encoding an unstable variant of GFP was engineered immediately downstream of the MYC ORF using CRISPR/Cas9, resulting in co-expression of both proteins from the endogenous MYC locus. Using fluorescence readout as a surrogate for MYC expression, we implemented a pilot screen in which ∼10,000 compounds were prosecuted. Among known MYC expression inhibitors, we identified cardiac glycosides and cytoskeletal disruptors to be quite potent. We demonstrate the power of CRISPR/Cas9 engineering in establishing phenotype-based assays to identify gene expression modulators.
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Affiliation(s)
- Jutta Steinberger
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Francis Robert
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Maxime Hallé
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - David E Williams
- Departments of Chemistry and Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Regina Cencic
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Neha Sawhney
- Vanderbilt Institute of Chemical Biology, Department of Chemistry, Vanderbilt University, Nashville, 37235, USA
| | - Dylan Pelletier
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Philip Williams
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Yasuhiro Igarashi
- Biotechnology Research Center, Toyama Prefectural University, Toyama 939-0398, Japan
| | - John A Porco
- Department of Chemistry, Center for Molecular Discovery (BU-CMD), Boston University, Boston, MA 02215, USA
| | - Abimael D Rodriguez
- Molecular Sciences Research Center, University of Puerto Rico, San Juan, PR 00926, USA
| | - Brigitte Kopp
- Department of Pharmacognosy, University of Vienna, Vienna, Austria
| | - Brian Bachmann
- Vanderbilt Institute of Chemical Biology, Department of Chemistry, Vanderbilt University, Nashville, 37235, USA
| | - Raymond J Andersen
- Departments of Chemistry and Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; The Rosalind and Morris Goodman Cancer Research Center and the Department of Oncology, McGill University, Montreal, QC, Canada.
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3
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Characterization of mRNA-cytoskeleton interactions in situ using FMTRIP and proximity ligation. PLoS One 2013; 8:e74598. [PMID: 24040294 PMCID: PMC3770708 DOI: 10.1371/journal.pone.0074598] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 08/04/2013] [Indexed: 12/23/2022] Open
Abstract
Many studies have demonstrated an association between the cytoskeleton and mRNA, as well as the asymmetric distribution of mRNA granules within the cell in response to various signaling events. It is likely that the extensive cytoskeletal network directs mRNA transport and localization, with different cytoskeletal elements having their own specific roles. In order to understand the spatiotemporal changes in the interactions between the mRNA and the cytoskeleton as a response to a stimulus, a technique that can visualize and quantify these changes across a population of cells while capturing cell-to-cell variations is required. Here, we demonstrate a method for imaging and quantifying mRNA-cytoskeleton interactions on a per cell basis with single-interaction sensitivity. Using a proximity ligation assay with flag-tagged multiply-labeled tetravalent RNA imaging probes (FMTRIP), we quantified interactions between mRNAs and β-tubulin, vimentin, or filamentous actin (F-actin) for two different mRNAs, poly(A) + and β-actin mRNA, in two different cell types, A549 cells and human dermal fibroblasts (HDF). We found that the mRNAs interacted predominantly with F-actin (>50% in HDF, >20% in A549 cells), compared to β-tubulin (<5%) and vimentin (11-13%). This likely reflects differences in mRNA management by the two cell types. We then quantified changes in these interactions in response to two perturbations, F-actin depolymerization and arsenite-induced oxidative stress, both of which alter either the cytoskeleton itself and mRNA localization. Both perturbations led to a decrease in poly(A) + mRNA interactions with F-actin and an increase in the interactions with microtubules, in a time dependent manner.
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4
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Kakegawa T, Ohuchi N, Hayakawa A, Hirata S, Matsuda M, Kogure K, Kobayashi H, Inoue A, Kaspar RL. Identification of AUF1 as a rapamycin-responsive binding protein to the 5'-terminal oligopyrimidine element of mRNAs. Arch Biochem Biophys 2007; 465:274-81. [PMID: 17603996 DOI: 10.1016/j.abb.2007.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Revised: 05/30/2007] [Accepted: 06/03/2007] [Indexed: 11/29/2022]
Abstract
In vertebrates, mRNAs containing a 5'-terminal oligopyrimidine (TOP) motif are coordinately post-transcriptionally regulated. Binding of specific proteins to this element has been proposed to downregulate expression of TOP mRNAs at the level of translational initiation. We previously reported that rapamycin induces binding activity to the TOP element of ribosomal protein (r-protein) L32 mRNA. In this study, we adapt DEAE-cellulose/oligo dT-cellulose tandem column chromatography to purify TOP element-binding proteins from bovine submaxillary lymph nodes (SLN). We also show by northwestern blot analysis that two proteins of molecular weight 47kDa (47BP) and 43kDa (43BP) specifically bind to a (32)P-labeled riboprobe containing TOP regulatory element of the r-protein L32. Microsequencing of the purified 47BP revealed an internal sequence of 15 amino acids identical to the consensus sequence of the 2x RBD-Gly family. Western blot analysis of the cytoplasm fractions using an AUF1 antibody revealed that these two proteins are p45 AUF1 and p42 AUF1. Increases of the four isoforms of AUF1 protein were observed in 100,000g supernatant fractions of rapamycin-administered rat SLN. Furthermore, decreases of p45 AUF1 and p42 and/or p40 AUF1 were observed in the polysomal fractions of BJAB cells in which translation of TOP mRNAs was selectively suppressed by rapamycin treatment. Taken together, these results suggest that AUF1 is a TOP mRNA-binding protein that may participate in the translational suppression of TOP mRNAs resulting from rapamycin treatment.
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Affiliation(s)
- Tomohito Kakegawa
- Faculty of Pharmaceutical Sciences, Josai International University, 1 Gumyo, Togane, Chiba 283-8555, Japan.
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5
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Gross SR, Kinzy TG. Improper organization of the actin cytoskeleton affects protein synthesis at initiation. Mol Cell Biol 2007; 27:1974-89. [PMID: 17178834 PMCID: PMC1820457 DOI: 10.1128/mcb.00832-06] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 06/14/2006] [Accepted: 12/07/2006] [Indexed: 11/20/2022] Open
Abstract
Although the actin cytoskeleton and the translation machinery are considered to be separate cellular complexes, growing evidence supports overlapping regulation of the two systems. Because of its interaction with actin, the eukaryotic translation elongation factor 1A (eEF1A) is proposed to be a regulator or link between these processes. Using a genetic approach with the yeast Saccharomyces cerevisiae, specific regions of eEF1A responsible for actin interactions and bundling were identified. Five new mutations were identified along one face of eEF1A. Dramatic changes in cell growth, cell morphology, and actin cable and patch formation as well as a unique effect on total translation in strains expressing the F308L or S405P eEF1A mutant form were observed. The translation effects do not correlate with reduced translation elongation but instead include an initiation defect. Biochemical analysis of the eEF1A mutant forms demonstrated reduced actin-bundling activity in vitro. Reduced total translation and/or the accumulation of 80S ribosomes in strains with either a mutation or a null allele of genes encoding actin itself or actin-regulating proteins Tpm1p, Mdm20p, and Bnirp/Bni1p was observed. Our data demonstrate that eEF1A, other actin binding proteins, and actin mutants affect translation initiation through the actin cytoskeleton.
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Affiliation(s)
- Stephane R Gross
- Department of Molecular Genetics, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854, USA
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Hollås H, Aukrust I, Grimmer S, Strand E, Flatmark T, Vedeler A. Annexin A2 recognises a specific region in the 3'-UTR of its cognate messenger RNA. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1325-34. [PMID: 17045350 DOI: 10.1016/j.bbamcr.2006.08.043] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 08/17/2006] [Accepted: 08/26/2006] [Indexed: 12/28/2022]
Abstract
Annexin A2 is a multifunctional Ca(2+)- and lipid-binding protein. We previously showed that a distinct pool of cellular Annexin A2 associates with mRNP complexes or polysomes associated with the cytoskeleton. Here we report in vitro and in vivo experiments showing that Annexin A2 present in this subset of mRNP complexes interacts with its cognate mRNA and c-myc mRNA, but not with beta(2)-microglobulin mRNA translated on membrane-bound polysomes. The protein recognises sequence elements within the untranslated regions, but not within the coding region, of its cognate mRNA. Alignment of the Annexin A2-binding 3'-untranslated regions of annexin A2 mRNA from several species reveals a five nucleotide consensus sequence 5'-AA(C/G)(A/U)G. The Annexin A2-interacting region of the 3'-untranslated region can be mapped to a sequence of about 100 nucleotides containing two repeats of the consensus sequence. The binding elements appear to involve both single and double stranded regions, indicating that a specific higher order mRNA structure is required for binding to Annexin A2. We suggest that this type of interaction is representative for a group of mRNAs translated on cytoskeleton-bound polysomes.
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Affiliation(s)
- Hanne Hollås
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway
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Mickleburgh I, Chabanon H, Nury D, Fan K, Burtle B, Chrzanowska-Lightowlers Z, Hesketh J. Elongation factor 1alpha binds to the region of the metallothionein-1 mRNA implicated in perinuclear localization--importance of an internal stem-loop. RNA (NEW YORK, N.Y.) 2006; 12:1397-407. [PMID: 16723660 PMCID: PMC1484432 DOI: 10.1261/rna.2730106] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
In eukaryotic cells, mRNA localization can provide local protein synthesis. Metallothionein-1 (MT-1) mRNA is associated with the perinuclear cytoskeleton, and this is essential for subsequent nuclear import of the protein. The present study defines the cis-acting localization signal and a trans-acting binding protein. Gel retardation and UV cross-linking assays using MT-1 3'UTR transcripts and CHO cell extracts revealed formation of a complex containing a approximately 50-kDa protein. Only localization-positive mutant transcripts competed for binding of this protein. Using an RNA affinity technique, Western blotting, mass spectrometry, and a supershift assay, the protein was identified as Elongation factor 1alpha (eEF1alpha). Mutation and deletion analysis showed that two regions, nucleotides 21-36 and 66-76, were required for both binding and localization. RNA-folding prediction combined with chemical and enzymatic probing experiments suggest that these regions are in juxtaposition within a stem/internal loop structure. Mutations that are predicted to alter this structure abrogate protein binding. Our hypothesis is that the cis-acting signal in MT-1 3'UTR is formed by this stem/internal loop, that it binds eEF1alpha, and that eEF1alpha-cytoskeleton interactions play a role in perinuclear mRNA localization.
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Affiliation(s)
- Ian Mickleburgh
- Institute for Cell and Molecular Biosciences, University of New Castle upon Tyne, UK
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8
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Chabanon H, Mickleburgh I, Burtle B, Pedder C, Hesketh J. An AU-rich stem-loop structure is a critical feature of the perinuclear localization signal of c-myc mRNA. Biochem J 2006; 392:475-83. [PMID: 16042622 PMCID: PMC1316286 DOI: 10.1042/bj20050812] [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] [Indexed: 11/17/2022]
Abstract
In eukaryotic cells, several mRNAs including those of c-myc and c-fos are localized to the perinuclear cytoplasm and associated with the cytoskeleton. The localization element of c-myc mRNA is present within its 3'UTR (3'-untranslated region) but the precise nature of this signal has remained unidentified. Chemical/enzymatic cleavage with RNases (ribonucleases) and lead have identified single-stranded and double-stranded regions in RNA transcripts of nucleotides 194-280 of the c-myc 3'UTR. Combined with computer predicted structure these results indicate that this region folds so that part of it forms a stem-loop structure. A mutation, that has been previously shown to prevent localization, leads to a different secondary RNA structure in this region as indicated by altered cleavage patterns. Competitive gel-retardation assays, using labelled transcripts corresponding to nucleotides 205-280 of c-myc 3'UTR, and fibroblast extracts revealed that the stem-loop region was sufficient for RNA-protein complex formation. In situ hybridization studies in cells transfected with reporter constructs, in which all or parts of the region corresponding to this stem-loop were linked to beta-globin, indicated that this region was sufficient for localization and that deletion of the nucleotides corresponding to the proposed upper-stem or terminal loop prevented localization. Our hypothesis is that an AU-rich stem-loop structure within nt 222-267 in the c-myc 3'UTR forms the perinuclear localization signal. Bioinformatic analysis suggests that this signal shares features with 3'UTRs of other localized mRNAs and that these features may represent a conserved form of signal in mRNA localization mechanisms.
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Affiliation(s)
- Hervé Chabanon
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle-upon-Tyne NE2 4HH, U.K
| | - Ian Mickleburgh
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle-upon-Tyne NE2 4HH, U.K
| | - Brian Burtle
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle-upon-Tyne NE2 4HH, U.K
| | - Christopher Pedder
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle-upon-Tyne NE2 4HH, U.K
| | - John Hesketh
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle-upon-Tyne NE2 4HH, U.K
- To whom correspondence should be addressed (email )
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9
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Nury D, Chabanon H, Levadoux-Martin M, Hesketh J. An eleven nucleotide section of the 3'-untranslated region is required for perinuclear localization of rat metallothionein-1 mRNA. Biochem J 2005; 387:419-28. [PMID: 15537387 PMCID: PMC1134970 DOI: 10.1042/bj20040630] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Localization of mRNAs provides a novel mechanism for synthesis of proteins close to their site of function. MT1 (metallothionein-1) is a small, metal-binding protein that is largely cytoplasmic but which can be found in the nucleus. The localization of rat MT1 requires the perinuclear localization of its mRNA by a mechanism dependent on the 3'-UTR (3'-untranslated region). The present study investigates the nature of this mRNA localization signal using Chinese-hamster ovary cells transfected with gene constructs in which either MT1 or the globin coding region is linked to different sequences from the MT1 3'-UTR. Deletion, mutagenesis and antisense oligonucleotide approaches indicate that nt 45-76 of the 3'-UTR, in particular nt 66-76, are required for the localization of either MT1 mRNA or chimaeric transcripts in which a beta-globin coding region is linked to sequences from the MT1 3'-UTR. This section of the 3'-UTR contains a CACC repeat. Two mutations that are predicted to alter the secondary structure of this region also impair localization. Our hypothesis is that the perinuclear localization signal in MT1 mRNA is formed by a combination of the CACC repeat and its structural context.
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Affiliation(s)
- David Nury
- School of Cell and Molecular Biosciences, Faculty of Medicine, University of Newcastle, Newcastle upon Tyne NE1 7RU, U.K
| | - Hervé Chabanon
- School of Cell and Molecular Biosciences, Faculty of Medicine, University of Newcastle, Newcastle upon Tyne NE1 7RU, U.K
| | - Marilyne Levadoux-Martin
- School of Cell and Molecular Biosciences, Faculty of Medicine, University of Newcastle, Newcastle upon Tyne NE1 7RU, U.K
| | - John Hesketh
- School of Cell and Molecular Biosciences, Faculty of Medicine, University of Newcastle, Newcastle upon Tyne NE1 7RU, U.K
- To whom correspondence should be addressed (email )
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10
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Martin-DeLeon PA, Zhang H, Morales CR, Zhao Y, Rulon M, Barnoski BL, Chen H, Galileo DS. Spam1-associated transmission ratio distortion in mice: elucidating the mechanism. Reprod Biol Endocrinol 2005; 3:32. [PMID: 16092963 PMCID: PMC1201170 DOI: 10.1186/1477-7827-3-32] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Accepted: 08/10/2005] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND While transmission ratio distortion, TRD, (a deviation from Mendelian ratio) is extensive in humans and well-documented in mice, the underlying mechanisms are unknown. Our earlier studies on carriers of spontaneous mutations of mouse Sperm Adhesion Molecule 1 (Spam1) suggested that TRD results from biochemically different sperm, due to a lack of transcript sharing through the intercellular cytoplasmic bridges of spermatids. These bridges usually allow transcript sharing among genetically different spermatids which develop into biochemically and functionally equivalent sperm. OBJECTIVES The goals of the study were to provide support for the lack of sharing (LOS) hypothesis, using transgene and null carriers of Spam1, and to determine the mechanism of Spam1-associated TRD. METHODS Carriers of Spam1-Hyal5 BAC transgenes were mated with wild-type female mice and the progeny analyzed for TRD by PCR genotyping. Sperm from transgene and Spam1 null carriers were analyzed using flow cytometry and immunocytochemistry to detect quantities of Spam1 and/or Hyal5. Transgene-bearing sperm with Spam1 overexpression were detected by fluorescence in situ hybridization. In wild-type animals, EM studies of in situ transcript hybridization of testis sections and Northern analysis of biochemically fractionated testicular RNA were performed to localize Spam1 transcript. Finally, AU-rich motifs identified in the 3' UTR of Spam1 RNA were assayed by UV cross-linking to determine their ability to interact with testicular RNA binding proteins. RESULTS The Tg8 line of transgene carriers had a significant (P < 0.001) TRD, due to reduced fertilizing ability of transgene-bearing sperm. These sperm retained large cytoplasmic droplets engorged with overexpressed Spam1 or Hyal5 protein. Caudal sperm from transgene carriers and caput sperm of null carriers showed a bimodal distribution of Spam1, indicating that the sperm in a male were biochemically different with respect to Spam1 quantities. Spam1 RNA was absent from the bridges, associated exclusively with the ER, and was shown to be anchored to the cytoskeleton. This compartmentalization of the transcript, mediated by cytoskeletal binding, occurs via protein interactions with 3' UTR AU-rich sequences that are likely involved in its stabilization. CONCLUSION We provide strong support for the LOS hypothesis, and have elucidated the mechanism of Spam1-associated TRD.
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Affiliation(s)
| | - Hong Zhang
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Carlos R Morales
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Yutong Zhao
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Michelle Rulon
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Barry L Barnoski
- Department of Genetics, Thomas Jefferson University, Philadelphia, PA, USA
| | - Hong Chen
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Deni S Galileo
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
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11
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Mickleburgh I, Burtle B, Hollås H, Campbell G, Chrzanowska-Lightowlers Z, Vedeler A, Hesketh J. Annexin A2 binds to the localization signal in the 3' untranslated region of c-myc mRNA. FEBS J 2005; 272:413-21. [PMID: 15654879 DOI: 10.1111/j.1742-4658.2004.04481.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Messenger RNA trafficking, which provides a mechanism for local protein synthesis, is dependent on cis-acting sequences in the 3' untranslated regions (3'UTRs) of the mRNAs concerned acting together with trans-acting proteins. The C-MYC transcription factor is a proto-oncogene product involved in cell proliferation, differentiation and apoptosis. Localization of c-myc mRNA to the perinuclear cytoplasm and its association with the cytoskeleton is determined by a signal in the 3'UTR. Here we show the specific binding of a trans-acting factor to the perinuclear localization element in the 3'UTR of c-myc mRNA and identify this protein as annexin A2. Gel retardation and UV cross-linking experiments showed that proteins in fibroblast extracts formed complexes with the region of c-myc 3'UTR implicated in localization; a protein of approximately 36 kDa exhibited specific, Ca(2+)-dependent binding. Binding was reduced by introduction of a mutation that abrogates localization. Using RNA-affinity columns followed by gel electrophoresis and mass spectrometry this protein was identified as annexin A2. The RNA-protein complex formed by cell extracts was further retarded by anti-(annexin A2). Purified annexin A2 bound to the same region of the c-myc 3'UTR but binding was reduced by introduction of a mutation, as with cell extracts. It is proposed that binding of annexin A2 to the localization signal in the c-myc mRNA leads to association with the cytoskeleton and perinuclear localization. The data indicate a novel functional role for the RNA-binding properties of annexin A2 in perinuclear localization of mRNA and the association with the cytoskeleton.
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Affiliation(s)
- Ian Mickleburgh
- School of Cell and Molecular Biosciences, University of Newcastle, Newcastle-upon-Tyne NE1 7RU, UK
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12
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Searles CD, Ide L, Davis ME, Cai H, Weber M. Actin Cytoskeleton Organization and Posttranscriptional Regulation of Endothelial Nitric Oxide Synthase During Cell Growth. Circ Res 2004; 95:488-95. [PMID: 15256481 DOI: 10.1161/01.res.0000138953.21377.80] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Posttranscriptional regulation of endothelial nitric oxide synthase (eNOS) expression is an important mechanism by which endothelial cells respond to various physiological and pathophysiological stimuli. Previously, we showed that eNOS expression was dramatically altered by the state of cell growth and that the mechanism responsible for this regulation was entirely posttranscriptional, occurring via changes in eNOS mRNA stability. The present study identifies a role for actin cytoskeleton organization in the posttranscriptional regulation of eNOS during cell growth and examines the relationship between the state of actin polymerization and eNOS expression. We identified monomeric actin (globular [G]-actin) as the major component of a 51-kDa ribonucleoprotein that binds to the eNOS mRNA 3' untranslated region in UV-crosslinking analysis. Binding activity of the ribonucleoprotein complex correlated with the relative concentration of G-actin versus filamentous actin (F-actin). ENOS transcripts colocalized with cytoplasmic G-actin in cells subjected to fluorescence in situ hybridization and G-actin fluorescence staining. In subcellular fractionation studies, eNOS transcripts were enriched in the free polysomal fraction of nonproliferating cells and enriched in the cell matrix-associated polysomal fraction of proliferating cells. Furthermore, an inverse relationship between the concentration of G-actin and eNOS expression was observed in endothelial cells subjected to pharmacological alteration of their cytoskeleton; lower G/F-actin ratios correlated with increased eNOS expression. Our findings provide some insight into how endothelial cells may use the dynamic organization of the actin cytoskeleton to regulate expression of an enzyme that is crucial to vascular homeostasis.
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Affiliation(s)
- Charles D Searles
- Division of Cardiology, Emory University, 1639 Pierce Dr, WMB 319, Atlanta, GA 30322, USA.
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13
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Bermano G, Shepherd RK, Zehner ZE, Hesketh JE. Perinuclear mRNA localisation by vimentin 3'-untranslated region requires a 100 nucleotide sequence and intermediate filaments. FEBS Lett 2001; 497:77-81. [PMID: 11377416 DOI: 10.1016/s0014-5793(01)02438-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The role of the vimentin 3'-untranslated region (3'-UTR) in mRNA localisation was studied in cells transfected with a reporter sequence linked to subregions of the 3'-UTR. In situ hybridisation showed that nucleotides 37-137, including a previously identified protein-binding domain, were sufficient to localise transcripts to perinuclear cytoplasm. Transfection of two SW13 cell lines that do and do not express vimentin showed that perinuclear localisation due to either the vimentin or c-myc 3'-UTR requires intermediate filaments. The data suggest that both a specific protein-binding region of the vimentin 3'-UTR and intermediate filaments themselves are required to determine the site of vimentin synthesis.
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Affiliation(s)
- G Bermano
- Intrecellular Targeting Group, Rowett Research Institute Aberdeen, UK
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Dalgleish G, Veyrune JL, Blanchard JM, Hesketh J. mRNA localization by a 145-nucleotide region of the c-fos 3'--untranslated region. Links to translation but not stability. J Biol Chem 2001; 276:13593-9. [PMID: 11139568 DOI: 10.1074/jbc.m001141200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The presence of a localization signal in the 3'-untranslated region of c-fos mRNA was investigated by in situ hybridization and cell fractionation techniques. Cells were transfected with chimeric gene constructs in which the beta-globin coding region was used as a reporter and linked to either its own 3'-untranslated region, the c-fos 3'-untranslated region, or the c-fos 3'-untranslated region containing different deletions. Replacement of the endogenous beta-globin 3'-untranslated region by that from c-fos caused a redistribution of the transcripts so that they were recovered in cytoskeletal-bound polysomes and seen localized in the perinuclear cytoplasm. Deletion of the AU-rich instability region did not affect transcript localization, but removal of a distinct 145-nucleotide region of the 3'-untranslated region abolished it. The prevention of transcript translation by desferrioxamine led to a marked loss of transcript localization, independent of mRNA instability. The data show that the 3'-untranslated region of c-fos mRNA, as c-myc, contains a localization signal, which targets the mRNA to the perinuclear cytoskeleton. We propose that this is important to ensure efficient nuclear import of these key regulatory proteins. mRNA localization by the fos 3'-untranslated region is independent of mRNA instability, and the two are determined by different regulatory elements.
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Affiliation(s)
- G Dalgleish
- Rowett Research Institute, Bucksburn, Aberdeen, AB21 9SB Scotland, United Kingdom
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15
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Vedeler A, Hollås H. Annexin II is associated with mRNAs which may constitute a distinct subpopulation. Biochem J 2000; 348 Pt 3:565-72. [PMID: 10839987 PMCID: PMC1221098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Protein-mRNA interactions affect mRNA transport, anchorage, stability and translatability in the cytoplasm. During the purification of three subpopulations of polysomes, it was observed that a 36-kDa protein, identified as annexin II, is associated with only one specific population of polysomes, namely cytoskeleton-associated polysomes. This association appears to be calcium-dependent since it was sensitive to EGTA and could be reconstituted in vitro. UV irradiation resulted in partial, EGTA-resistant cross-linking of annexin II to the polysomes. Binding of (32)P-labelled total RNA to proteins isolated from the cytoskeleton-bound polysomes on a NorthWestern blot resulted in a radioactive band having the same mobility as annexin II and, most importantly, purified native annexin II immobilized on nitrocellulose specifically binds mRNA. The mRNA population isolated from cytoskeleton-bound polysomes binds to annexin II with the highest affinity as compared with those isolated from free or membrane-bound polysomes. Interestingly, the annexin II complex, isolated from porcine small intestinal microvilli was a far better substrate for mRNA binding than the complex derived from transformed Krebs II ascites cells. When cytoskeleton-associated polysomes were split into 60 S and 40 S ribosomal subunits, and a peak containing mRNA complexes, annexin II fractionated with the mRNAs. Finally, using affinity purification of mRNA on poly(A)(+)-coupled magnetic beads, annexin II was only detected in association with messenger ribonucleoproteins (mRNPs) present in the cytoskeletal fraction (non-polysomal mRNPs). These results, derived from both in vitro experiments and cell fractionation, suggest that annexin II binds directly to the RNA moiety of mRNP complexes containing a specific population of mRNAs.
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Affiliation(s)
- A Vedeler
- Department of Biochemistry and Molecular Biology, University of Bergen, Arstadveien 19, N-5009 Bergen, Norway.
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16
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Dalgleish GD, Veyrune JL, Accornero N, Blanchard JM, Hesketh JE. Localisation of a reporter transcript by the c-myc 3'-UTR is linked to translation. Nucleic Acids Res 1999; 27:4363-8. [PMID: 10536143 PMCID: PMC148717 DOI: 10.1093/nar/27.22.4363] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The 3'-untranslated region of c-myc mRNA contains a perinuclear localisation signal which is sufficient to target beta-globin coding sequences. The link between perinuclear mRNA localisation and translation has been investigated using cells transfected with chimeric gene constructs in which globin reporter sequences were linked to the c-myc 3'-untranslated region and the iron-responsive element from ferritin mRNA. Iron supplementation of the medium promoted translation of the chimeric mRNA as assessed by its presence in polysomes; in situ hybridisation showed that the mRNA was localised around the nucleus. Treatment with the iron chelator desferrioxamine for 16 h prevented both translation and mRNA localisation. In controls where the expressed mRNA lacked the iron-responsive element desferrioxamine had no effect upon localisation. In contrast, arrest of on-going global translation by puromycin treatment had no effect on mRNA localisation. The data suggest that if initiation of translation of a mRNA containing the c-myc localisation signal is prevented in some way then localisation does not occur, whereas once the mRNA has been localised further translation is not required to maintain mRNA localisation.
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Affiliation(s)
- G D Dalgleish
- Intracellular Targeting Group, Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB, UK
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17
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Morelli JK, Zhou W, Yu J, Lu C, Vayda ME. Actin depolymerization affects stress-induced translational activity of potato tuber tissue. PLANT PHYSIOLOGY 1998; 116:1227-37. [PMID: 9536039 PMCID: PMC35029 DOI: 10.1104/pp.116.4.1227] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/1997] [Accepted: 12/07/1997] [Indexed: 05/21/2023]
Abstract
Changes in polymerized actin during stress conditions were correlated with potato (Solanum tuberosum L.) tuber protein synthesis. Fluorescence microscopy and immunoblot analyses indicated that filamentous actin was nearly undetectable in mature, quiescent aerobic tubers. Mechanical wounding of postharvest tubers resulted in a localized increase of polymerized actin, and microfilament bundles were visible in cells of the wounded periderm within 12 h after wounding. During this same period translational activity increased 8-fold. By contrast, low-oxygen stress caused rapid reduction of polymerized actin coincident with acute inhibition of protein synthesis. Treatment of aerobic tubers with cytochalasin D, an agent that disrupts actin filaments, reduced wound-induced protein synthesis in vivo. This effect was not observed when colchicine, an agent that depolymerizes microtubules, was used. Neither of these drugs had a significant effect in vitro on run-off translation of isolated polysomes. However, cytochalasin D did reduce translational competence in vitro of a crude cellular fraction containing both polysomes and cytoskeletal elements. These results demonstrate the dependence of wound-induced protein synthesis on the integrity of microfilaments and suggest that the dynamics of the actin cytoskeleton may affect translational activity during stress conditions.
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Affiliation(s)
- JK Morelli
- Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, Maine 04469-5735, USA
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18
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Henics T, Nagy E, Szekeres-Barthó J. Interaction of AU-rich sequence binding proteins with actin: possible involvement of the actin cytoskeleton in lymphokine mRNA turnover. J Cell Physiol 1997; 173:19-27. [PMID: 9326445 DOI: 10.1002/(sici)1097-4652(199710)173:1<19::aid-jcp3>3.0.co;2-m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In the current study, we report that cytochalasin-induced disruption of microfilaments stabilizes lymphokine mRNAs in activated human peripheral blood lymphocytes. Parallel with this, a dose- and time-dependent increase in AU-rich sequence binding protein (AUPB) activities is apparent in the nonionic detergent-resistant fractions of these cells, suggesting that cytochalasin-induced modulation of lymphokine mRNA stability might be mediated through cytoplasmic AUBPs. We provide evidence that some of the AUBPs can be immunoprecipitated with anti-actin antibodies, implicating the potential of these proteins to associate with the actin-based cytoskeleton in vivo. Moreover, disruption of the microfilament network by cytochalasins produces increased immunoprecipitable actin-AUBP complexes in the detergent-resistant cytoplasmic subfractions of lymphocytes. We show that cytochalasin-induced changes in AUBP activities are parallel with their higher binding affinity to RNA containing AU-rich instability sequence element as judged by in vitro competition and in vivo ultraviolet-crosslinking analysis. Correlation of these findings with changes in mRNA stability indicates that the actin cytoskeleton may play a physiologically important role in posttranscriptional regulation of lymphokine gene expression during early lymphocyte activation.
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Affiliation(s)
- T Henics
- Department of Microbiology, University Medical School of Pécs, Hungary.
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19
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Mahon P, Partridge K, Beattie JH, Glover LA, Hesketh JE. The 3' untranslated region plays a role in the targeting of metallothionein-I mRNA to the perinuclear cytoplasm and cytoskeletal-bound polysomes. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1358:153-62. [PMID: 9332451 DOI: 10.1016/s0167-4889(97)00058-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The mechanism of localisation of metallothionein-I (MT-I) mRNA was studied in transfected cells by in situ hybridisation and cell fractionation. Hepatoma cells were transfected with the 5'-untranslated region and coding region of the beta-globin gene alone or linked to either the beta-globin 3'-untranslated region (3'-UTR) or the MT-I 3'-UTR. The wild-type beta-globin mRNA and the beta-globin mRNA lacking its native 3'-UTR were present in free and cytoskeletal-bound polysomes to a similar extent and showed no localisation. Chimaeric globin-metallothionein transcripts were significantly enriched in cytoskeletal-bound polysomes and were localised in the perinuclear cytoplasm. Chimaeric globin-metallothionein and wild-type globin transcripts were of similar stability. Chinese Hamster Ovary cells were transfected with constructs in which the MT-I 5'-untranslated region and coding sequences were linked to either the endogenous 3'-UTR or the glutathione peroxidase 3'-UTR. Wild-type MT-I transcripts were localised in the perinuclear cytoplasm but the chimaeric MT-I-glutathione peroxidase transcripts showed no distinct localisation. The results indicate that the 3'-UTR of MT-I mRNA contains a localisation signal which promotes both the association of the mRNA with the cytoskeleton and its perinuclear localisation.
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Affiliation(s)
- P Mahon
- Intracellular Targeting Group, Rowett Research Institute, Bucksburn, Aberdeen, UK
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20
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Veyrune JL, Hesketh J, Blanchard JM. 3' untranslated regions of c-myc and c-fos mRNAs: multifunctional elements regulating mRNA translation, degradation and subcellular localization. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1997; 18:35-63. [PMID: 8994260 DOI: 10.1007/978-3-642-60471-3_3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- J L Veyrune
- Institut de Génétique Moléculaire de Montpellier, CNRS, UMR 5535, Montpellier, France
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21
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Hovland R, Hesketh JE, Pryme IF. The compartmentalization of protein synthesis: importance of cytoskeleton and role in mRNA targeting. Int J Biochem Cell Biol 1996; 28:1089-105. [PMID: 8930133 DOI: 10.1016/1357-2725(96)00059-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Following the synthesis of mRNA molecules in eukaryotic cells, the transcripts are processed in the nucleus and subsequently transported through the nuclear membrane into the cytoplasm before being sequestered into polysomes where the information contained in the RNA molecule is translated into an amino acid sequence. Recent evidence suggests that an association of mRNAs with the cytoskeleton might be important in targeting mechanisms and, furthermore, in the transport of mRNA from the nucleus to its correct location in the cytoplasm. Until recently, polysomes have been considered to exist in two classes, namely free or membrane-bound. There is now compelling evidence, however, that ribosomes, in addition to being associated with endoplasmic reticulum membranes, also are associated with components of the cytoskeleton. Thus, a large number of morphological and biochemical studies have shown that mRNA, polysomes and translational factors are associated with cytoskeletal structures. Although the actual nature and significance of the interaction between components of the translational apparatus and the cytoskeleton is not yet understood in detail, it would seem evident that such interactions are important in both the spatial organization and control of protein synthesis. Recent work has shown that a subcellular fraction, enriched in cytoskeletal components, contains polysomes and these (cytoskeletal-bound) polysomes have been shown to contain specific mRNA species. Thus, a population of cytoskeletal-bound polysomes may provide a specialized mechanism for the sorting, targeting and topographical segregation of mRNAs. In this review, current knowledge of the subcellular compartmentalization of mRNAs is discussed.
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Affiliation(s)
- R Hovland
- Department of Biochemistry and Molecular Biology, University of Bergen, Norway
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22
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Veyrune JL, Campbell GP, Wiseman J, Blanchard JM, Hesketh JE. A localisation signal in the 3′ untranslated region of c-myc mRNA targets c-myc mRNA and beta-globin reporter sequences to the perinuclear cytoplasm and cytoskeletal-bound polysomes. J Cell Sci 1996; 109 ( Pt 6):1185-94. [PMID: 8799809 DOI: 10.1242/jcs.109.6.1185] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There is increasing evidence that in mammalian cells some mRNAs are localised to specific parts of the cytoplasm and a proportion of mRNAs and polyribosomes are associated with the cytoskeleton. It has been shown previously that c-myc mRNA is present in the perinuclear cytoplasm and associated with the cytoskeleton, and that this localisation is dependent upon the 3′ untranslated region of the mRNA. The present studies show that in transfected fibroblasts the c-myc 3′ untranslated region is able to localise beta-globin reporter sequences to the perinuclear cytoplasm. Studies with constructs containing deletions within the 3′ untranslated region identify the region between bases 194 and 280 as critical for localisation. Transfection of cells with constructs in which this region is linked to beta-globin sequences showed that it was sufficient to localise the chimaeric transcripts to the perinuclear cytoplasm and to cytoskeletal-bound polyribosomes. Transfection with constructs containing a mutated AUUUA sequence within the 194–280 base region showed that this conserved AUUUA is required for targeting of both c-myc mRNA and a chimaeric transcript of beta-globin transcripts linked to the c-myc 3′ untranslated region. The region between bases 194 and 280 did not induce instability of beta-globin transcripts and the AUUUA mutation had little effect upon mRNA stability. We propose that this 86 nt region of the 3′ untranslated region contains a localisation signal to target c-myc mRNA so that it is retained on cytoskeletal-bound polysomes in the perinuclear cytoplasm; a conserved AUUUA sequence appears to be a critical part of this signal.
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Affiliation(s)
- J L Veyrune
- Institut de Genetique Moleculaire de Montpellier, UMR 5535, CNRS, Montpellier, France
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23
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Mahon P, Beattie J, Glover LA, Hesketh J. Localisation of metallothionein isoform mRNAs in rat hepatoma (H4) cells. FEBS Lett 1995; 373:76-80. [PMID: 7589438 DOI: 10.1016/0014-5793(95)01000-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The localisation of metallothionein isoform mRNAs in rat hepatoma (H4) cells was investigated using two approaches, namely Northern hybridisation of total RNA extracted from free, cytoskeletal-bound and membrane-bound polysomes isolated by a sequential detergent/salt extraction procedure and in situ hybridisation. The cytoskeletal-bound polysomes were enriched in metallothionein-I (MT-I) and c-myc mRNAs but showed a significantly lower enrichment in MT-II mRNA. These findings indicate that the MT-I mRNA is localised to the cytoskeleton during translation. In situ hybridisation using a biotin-labelled oligonucleotide probe revealed a predominantly perinuclear localisation for the MT-I mRNA.
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Affiliation(s)
- P Mahon
- Division of Biochemical Sciences, Rowett Research Institute, Aberdeen, Scotland, UK
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24
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Oral H, Kapadia S, Nakano M, Torre-Amione G, Lee J, Lee-Jackson D, Young JB, Mann DL. Tumor necrosis factor-alpha and the failing human heart. Clin Cardiol 1995; 18:IV20-7. [PMID: 7489617 DOI: 10.1002/clc.4960181605] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Tumor necrosis factor-alpha (TNF alpha) is a proinflammatory cytokine with negative inotropic effects. Recently, elevated levels of TNF alpha have been identified in patients with advanced heart failure. Although the clinical significance of this finding is unclear at present, there is increasing evidence that this cytokine may play a primary pathophysiologic role in the development and pathogenesis of heart failure in humans. Indeed, many of the clinical hallmarks of heart failure, including left ventricular dysfunction, cardiomyopathy, and pulmonary edema can be explained by the known biological effects of TNF alpha in humans. The present review will summarize recent evidence with regard to the biological role for TNF alpha in the adult mammalian heart, as well as summarize the increasing body of clinical information that implicates this cytokine in the pathophysiology of heart failure.
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Affiliation(s)
- H Oral
- Department of Medicine, Veterans Administration Medical Center, Houston, TX 77030, USA
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25
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Hovland R, Campbell G, Pryme I, Hesketh J. The mRNAs for cyclin A, c-myc and ribosomal proteins L4 and S6 are associated with cytoskeletal-bound polysomes in HepG2 cells. Biochem J 1995; 310 ( Pt 1):193-6. [PMID: 7646444 PMCID: PMC1135872 DOI: 10.1042/bj3100193] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Cytosolic, cytoskeleton and membrane fractions were extracted from HepG2 cells by a sequential detergent/salt extraction procedure. The cytosolic fraction contained 93% of the lactic dehydrogenase activity while the cytoskeleton fraction was enriched in actin and vimentin. The distribution of mRNAs for c-myc, glucose transporter 1, ribosomal proteins L4 and S6 and cyclin A were investigated by Northern hybridization of total RNA extracted from polysomes isolated from cytosolic, cytoskeleton and membrane fractions. The membrane-bound polysomes were enriched in the glucose transporter 1 mRNA and the cytoskeleton-bound polysomes were enriched in the mRNAs for the two ribosomal proteins, c-myc and cyclin A. The results suggest that the mRNAs for nuclear proteins are one class of mRNAs which are translated on polysomes associated with the cytoskeleton; this may be related to the requirement to transport the newly synthesized protein to the nucleus.
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Affiliation(s)
- R Hovland
- Department of Biochemistry and Molecular Biology, University of Bergen, Norway
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26
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Johannessen AJ, Pyrme IF, Vedeler A. Changes in distribution of actin mRNA in different polysome fractions following stimulation of MPC-11 cells. Mol Cell Biochem 1995; 142:107-15. [PMID: 7770062 DOI: 10.1007/bf00928931] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Individual mRNA species have been shown to differ both with respect to localization in the cell, and in their distribution upon stimulation of cells with different signals. In this study we have examined the distribution of actin mRNA in the free, cytoskeletal-bound, and membrane-bound RNA fractions, both in starved cells, and in response to stimulation by feeding. These results were then compared with mRNAs for glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and histone H4. The results we obtained showed that actin mRNA was located in the free RNA fraction in starved cells, while upon stimulation it was located both in the free, and in the cytoskeletal fraction; no redistribution of GAPDH mRNA occurred between the three RNA fractions, while H4 mRNA showed a different localization upon stimulation. Incubation with the drugs actinomycin-D and cycloheximide showed that an altered localization of actin mRNA from free in starved cells to free and cytoskeletal mRNA fractions following stimulation, was dependent on RNA synthesis, and not on protein synthesis.
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Affiliation(s)
- A J Johannessen
- Department of Biochemistry and Molecular Biology, University of Bergen, Norway
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27
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The Sequestration of mRNA in the Cytoskeleton and Other Subcellular Structures. Cytoskeleton (Hoboken) 1995. [DOI: 10.1016/s1569-2558(08)60259-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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28
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Abstract
This review describes the critical evidence that in eukaryotic cells polyribosomes, mRNAs and components of the protein synthetic machinery are associated with the cytoskeleton. The role of microtubules, intermediate filaments and microfilaments are discussed; at present most evidence suggests that polyribosomes interact with the actin filaments. The use of non-ionic detergent/deoxycholate treatment in the isolation of cytoskeletal-bound polysomes is described and the conclusion reached that at low salt concentrations this leads to mixed preparations of polysomes derived from both the cytoskeleton and the endoplasmic reticulum. At present the best approach for isolation of cytoskeletal-bound polysomes appears to involve extraction with salt concentrations greater than 130 mM after an initial non-ionic detergent treatment. Such polysomes appear to be enriched in certain mRNAs and thus it is suggested that they are involved in translation of a unique set of proteins. The evidence for mRNA localisation is presented and the role of the cytoskeleton in transport and localisation of RNA discussed. Recent data on the role of the 3' untranslated region in the targeting of mRNAs both to particular regions of the cell and for translation on cytoskeletal-bound polysomes is described. The hypothesis is developed that the association of polysomes with the cytoskeleton is the basis of a mechanism for the targeting of mRNAs and the compartmentalization of protein synthesis.
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Affiliation(s)
- J Hesketh
- Division of Biochemical Sciences, Rowett Research Institute, Bucksburn, Aberdeen, UK
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29
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Moss R, Pryme IF, Vedeler A. Free, cytoskeletal-bound and membrane-bound polysomes isolated from MPC-11 and Krebs II ascites cells differ in their complement of poly(A) binding proteins. Mol Cell Biochem 1994; 131:131-9. [PMID: 8035778 DOI: 10.1007/bf00925949] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A three-step detergent/salt extraction procedure (Vedeler et al., Mol Cell Biochem 100: 183-193, 1991) was used to isolate free polysomes (FP), cytoskeletal-bound polysomes (CBP) and membrane-bound polysomes (MBP) from MPC-11 and Krebs II ascites cells. Polysomes were pelleted, washed with high salt buffer and re-pelleted. Proteins in the dialysed high-salt extracts were subjected to poly(A) Sepharose chromatography and poly(A) binding and non-binding proteins were separated by SDS-PAGE. In MPC-11 cells the FP fraction contains thirteen poly(A) binding proteins and four non-poly(A) binding proteins while the corresponding fraction in Krebs II ascites cells has four poly(A) binding proteins and six proteins which do not bind poly(A). The CBP fraction isolated from MPC-11 cells has a complement of ten poly(A) binding proteins, four which are non-poly(A) binding, and a protein of 105 kDa which has both poly(A) binding and non-poly(A) binding properties. In the CBP fraction prepared from Krebs II ascites cells a protein band at 32 kDa exhibits both poly(A) binding and non-poly(A) binding properties. In this fraction there are six poly(A) binding proteins and an additional eight which do not bind poly(A). Of the total number of proteins eight of these have a molecular weight below 40 kDa. The MBP fraction in MPC-11 cells contains three poly(A) binding proteins and eleven with non-poly(A) binding properties. In contrast this fraction in Krebs II ascites cells has a complement of thirteen poly(A) binding and ten non-poly(A) binding proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R Moss
- Department of Biochemistry and Molecular Biology, University of Bergen, Norway
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30
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Hesketh J, Campbell G, Piechaczyk M, Blanchard JM. Targeting of c-myc and beta-globin coding sequences to cytoskeletal-bound polysomes by c-myc 3' untranslated region. Biochem J 1994; 298 ( Pt 1):143-8. [PMID: 8129712 PMCID: PMC1137994 DOI: 10.1042/bj2980143] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The influence of the 3' untranslated region on mRNA localization was investigated by measuring the distribution of myc, beta-globin and hybrid myc-globin mRNAs between free, cytoskeletal-bound and membrane-bound polysomes in cells transfected with either control or chimeric gene constructs. c-myc sequences and beta-globin-coding sequences linked to the myc 3' untranslated region were present at greatest enrichment in cytoskeletal-bound polysomes. beta-Globin mRNA and myc-coding sequences linked to the beta-globin 3' untranslated region were recovered largely in the free polysomes. In situ hybridization confirmed that replacement of the c-myc 3' untranslated region by that of globin caused a relocalization of the mRNA. The results suggest that mRNA localization in differentiated eukaryotic cells depends on a mechanism that involves directional information in the 3' untranslated region of mRNAs.
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Affiliation(s)
- J Hesketh
- Division of Biochemical Sciences, Rowett Research Institute, Aberdeen, Scotland, U.K
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31
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Kirkeeide EK, Pryme IF, Vedeler A. Microfilaments and protein synthesis; effects of insulin. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1993; 25:853-64. [PMID: 8344442 DOI: 10.1016/0020-711x(93)90240-f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- E K Kirkeeide
- Department of Biochemistry and Molecular Biology, University of Bergen, Norway
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32
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Abstract
The cytoskeleton of most cells is complex and spatially diverse. The mRNAs for some cytoskeletal proteins are localized, suggesting that synthesis of these proteins may occur at sites appropriate for function or assembly. mRNA concentrations were first observed for several oocyte and embryonic mRNAs. Some insight has been gained into the mechanisms that help to position these mRNAs. More surprising to some, many cytoskeletal mRNAs are also localized. Among them are mRNAs for actin, tubulin, intermediate filaments, and a variety of associated proteins. Different mRNAs in the same cell can be located in different places; the same mRNA can be located in different places; the same mRNA can be located differently at different times of development. For example, we observed vimentin mRNA in developing chicken muscle cultures by fluorescent in situ hybridization. We found that vimentin mRNA takes on a variety of positions during myogenesis, ending up located with its cognate protein at costameres. This last pattern is significant because it is too finely structured to have a function in the soluble phase and probably reflects cotranslational assembly of this particular protein. Analogies can be made between oocyte or embryonic positions (animal/vegetal poles, oocyte cortex, and interior) and somatic cell positions (anterior/posterior and cell cortex/cell center). These analogies may point to conserved mechanisms for moving and retaining mRNA. Localization of cytoskeletal synthesis, through the mRNA or by other means, may prove as important for assembling and maintaining differentiated cytoskeletal structures and somatic cells as mRNA location is for organizing the embryo. Mechanisms that permit mRNA localization are likely to be conserved.
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Affiliation(s)
- A B Fulton
- Department of Biochemistry, University of Iowa, City 52242
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33
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Kirkeeide EK, Pryme IF, Vedeler A. Morphological changes in Krebs II ascites tumour cells induced by insulin are associated with differences in protein composition and altered amounts of free, cytoskeletal-bound and membrane-bound polysomes. Mol Cell Biochem 1992; 118:131-40. [PMID: 1293508 DOI: 10.1007/bf00299392] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A three-step sequential detergent/salt extraction procedure was used in order to isolate three distinct subcellular fractions containing free (FP), cytoskeletal-bound (CBP) and membrane-bound polysomes (MBP), respectively, from Krebs II ascites cells (Vedeler et al., Mol Cell Biochem 100: 183-193, 1991). The purpose was to study changes in the distribution of polysomes in these three fractions during long-term incubation with insulin under either stationary conditions or in roller suspension culture. Insulin caused a redistribution of polysomes between FP, CBP and MBP fractions. The hormone appeared to promote an entry of ribosomes into polysomes both in CBP and MBP populations. When cells were grown in stationary culture in the presence of insulin and thus promoted to attach to the substratum and undergo morphological changes, a diversion of ribosomes from CBP into MBP was observed. The level of protein synthesis was apparently very high in this latter fraction since more than 70% of ribosomes were in polysomes. Morphological changes observed following insulin treatment were accompanied by a shift of certain proteins among subcellular fractions (for example actin and p35). The fibronectin content was about 20% higher in attached compared to non-attached cells. The results suggest that morphological changes induced by stimulation with insulin are associated with an increased activity of MBP, presumably reflecting a requirement for an increased synthesis of membrane proteins.
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Affiliation(s)
- E K Kirkeeide
- Department of Biochemistry, University of Bergen, Norway
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Henriksson M, Classon M, Axelson H, Klein G, Thyberg J. Nuclear colocalization of c-myc protein and hsp70 in cells transfected with human wild-type and mutant c-myc genes. Exp Cell Res 1992; 203:383-94. [PMID: 1459202 DOI: 10.1016/0014-4827(92)90012-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Using immunofluorescence and electron microscopy we have studied the localization of wild-type and mutant c-myc proteins transiently expressed in CV-1 cells. In agreement with our previous observations, wild-type c-myc protein accumulated in large amorphous globules in the nucleus. All mutant proteins tested accumulated in the nucleus as well, but gave rise to morphologically different inclusion bodies. Many small globules appeared in cells transfected with D145-262 (deletion of amino acids 145-262), while cells transfected with D371-412 or D414-433 generated structures looking like a fine network or like beads on a string. In addition, a particulate cytoplasmic staining appeared in some cells transfected with the wild-type gene and in cells transfected with mutants D145-262 or D414-433. Since the c-myc protein has been reported to stimulate expression of exogenous hsp70 protein, we also examined the intracellular distribution of hsp70 in the transfected cells. Double immunofluorescence microscopy revealed that hsp70 codistributed with the c-myc protein in distinct globules in the nucleus of many but not all myc-positive cells. However, the levels of hsp70 transcripts were not significantly raised compared to nontransfected and vector-transfected cells. Likewise, the levels of hsp70 protein did not vary significantly. These findings indicate that overexpression of c-myc stimulates translocation of preexisting hsp70 from the cytoplasm into the nucleus, rather than influencing hsp70 expression. Conceivably, this may represent one of several mechanisms whereby the cell deals with excessive amounts of c-myc protein.
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Affiliation(s)
- M Henriksson
- Department of Tumor Biology, Karolinska Institutet, Stockholm, Sweden
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Almås B, Vedeler A, Pryme IF. The effects of insulin, cycloheximide and phalloidin on the content of actin and p35 in extracts prepared from the nuclear fraction of Krebs II ascites cells. Mol Cell Biochem 1992; 115:187-94. [PMID: 1448063 DOI: 10.1007/bf00230330] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The nuclear fraction isolated from Krebs II ascites cells following cell disruption by nitrogen cavitation was separated into four fractions by salt/detergent extraction: NP-40 soluble fraction, 130 mM KCl extract, DOC/Triton x 100 soluble fraction and salt/detergent treated nuclei. The protein composition of the individual fractions was studied by SDS-PAGE and the relative amounts of actin and a 35 kDa protein (p35) were measured from gel scans. There was a time-dependent shift of actin from the 130 mM KCl extract to the NP-40 soluble fraction upon storage of the nuclear fraction on ice, indicating a progressive depolymerization of microfilaments. Compared with actin there was a slower release of p35 into the NP-40 soluble fraction. The results suggest that p35 is not integrated in the microfilament network. Phalloidin, which stabilizes the microfilaments, enriched the amount of both proteins in the 130 mM KCl extracts, together with a series of other proteins in the range 50-205 kDa. The presence of phalloidin also resulted in a large increase in the actin content in both the DOC/Triton x 100 extract and the fraction containing salt/detergent treated nuclei. Incubation of cells with insulin and/or cycloheximide enriched the amount of actin in the 130 mM KCl fraction. The results show that short term incubation of cells with phalloidin, insulin or cycloheximide increases the actin content of the nuclear fraction and also affects the presence of several other proteins.
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Affiliation(s)
- B Almås
- Department of Biochemistry, University of Bergen, Norway
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Rees WD, Hay SM, Flint HJ. Expression of Escherichia coli homoserine kinase in mouse 3T3 cells. Biochem J 1992; 281 ( Pt 3):865-70. [PMID: 1371387 PMCID: PMC1130769 DOI: 10.1042/bj2810865] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Escherichia coli gene for homoserine kinase (thrB) has been cloned into a simian-virus-40-based eukaryotic expression vector which also includes a neomycin-resistance gene. Mouse 3T3 cells transfected with this plasmid were selected for resistance and screened for homoserine kinase activity. It has thus been possible to isolate clones which are capable of accumulating homoserine O-phosphate when supplied with homoserine. In broken-cell preparations the kinetic constants for the production of homoserine O-phosphate were similar to those of the wild-type E. coli enzyme. These experiments demonstrate that E. coli homoserine kinase can be expressed in an animal cell and that it can successfully phosphorylate L-homoserine in the intact cell utilizing endogenous ATP.
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Affiliation(s)
- W D Rees
- Rowett Research Institute, Scotland, U.K
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Affiliation(s)
- J E Hesketh
- Division of Biochemical Sciences, Rowett Research Institute, Bucksburn, Aberdeen, U.K
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