1
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Chvalova V, Vomastek T, Grousl T. Comparison of holotomographic microscopy and coherence-controlled holographic microscopy. J Microsc 2024; 294:5-13. [PMID: 38196346 DOI: 10.1111/jmi.13260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/18/2023] [Accepted: 12/26/2023] [Indexed: 01/11/2024]
Abstract
Quantitative phase imaging (QPI) is a powerful tool for label-free visualisation of living cells. Here, we compare two QPI microscopes - the Telight Q-Phase microscope and the Nanolive 3D Cell Explorer-fluo microscope. Both systems provide unbiased information about cell morphology, such as individual cell dry mass, perimeter and area. The Q-Phase microscope uses artefact-free, coherence-controlled holographic imaging technology to visualise cells in real time with minimal phototoxicity. The 3D Cell Explorer-fluo employs laser-based holotomography to reconstruct 3D images of living cells, visualising their internal structures and dynamics. Here, we analysed the strengths and limitations of both microscopes when examining two morphologically distinct cell lines - the cuboidal epithelial MDCK cells which form multicellular clusters and solitary growing Rat2 fibroblasts. We focus mainly on the ability of the devices to generate images suitable for single-cell segmentation by the built-in software, and we discuss the segmentation results and quantitative data generated from the segmented images. We show that both microscopes offer slightly different advantages, and the choice between them depends on the specific requirements and goals of the user.
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Affiliation(s)
- Vera Chvalova
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
- Faculty of Science, Department of Cell Biology, Charles University, Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Tomas Grousl
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
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2
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Chvalova V, Venkadasubramanian V, Klimova Z, Vojtova J, Benada O, Vanatko O, Vomastek T, Grousl T. Characterization of RACK1-depleted mammalian cells by a palette of microscopy approaches reveals defects in cell cycle progression and polarity establishment. Exp Cell Res 2023:113695. [PMID: 37393981 DOI: 10.1016/j.yexcr.2023.113695] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 06/08/2023] [Accepted: 06/22/2023] [Indexed: 07/04/2023]
Abstract
The Receptor for Activated C Kinase 1 (RACK1) is an evolutionarily conserved scaffold protein involved in the regulation of numerous cellular processes. Here, we used CRISPR/Cas9 and siRNA to reduce the expression of RACK1 in Madin-Darby Canine Kidney (MDCK) epithelial cells and Rat2 fibroblasts, respectively. RACK1-depleted cells were examined using coherence-controlled holographic microscopy, immunofluorescence, and electron microscopy. RACK1 depletion resulted in decreased cell proliferation, increased cell area and perimeter, and in the appearance of large binucleated cells suggesting a defect in the cell cycle progression. Our results show that the depletion of RACK1 has a pleiotropic effect on both epithelial and mesenchymal cell lines and support its essential role in mammalian cells.
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Affiliation(s)
- Vera Chvalova
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic; Faculty of Science, Charles University, 128 00, Prague, Czech Republic
| | - Vignesh Venkadasubramanian
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic; Faculty of Science, Charles University, 128 00, Prague, Czech Republic
| | - Zuzana Klimova
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic
| | - Jana Vojtova
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 00, Prague, Czech Republic
| | - Oldrich Benada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, 142 00, Prague, Czech Republic
| | - Ondrej Vanatko
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the Czech Academy of Sciences, 142 00, Prague, Czech Republic; Second Faculty of Medicine, Charles University, 150 06, Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic
| | - Tomas Grousl
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic.
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3
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Rasl J, Grusanovic J, Klimova Z, Caslavsky J, Grousl T, Novotny J, Kolar M, Vomastek T. ERK2 signaling regulates cell-cell adhesion of epithelial cells and enhances growth factor-induced cell scattering. Cell Signal 2022; 99:110431. [PMID: 35933033 DOI: 10.1016/j.cellsig.2022.110431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/13/2022] [Accepted: 08/01/2022] [Indexed: 11/30/2022]
Abstract
The ERK signaling pathway, consisting of core protein kinases Raf, MEK and effector kinases ERK1/2, regulates various biological outcomes such as cell proliferation, differentiation, apoptosis, or cell migration. Signal transduction through the ERK signaling pathway is tightly controlled at all levels of the pathway. However, it is not well understood whether ERK pathway signaling can be modulated by the abundance of ERK pathway core kinases. In this study, we investigated the effects of low-level overexpression of the ERK2 isoform on the phenotype and scattering of cuboidal MDCK epithelial cells growing in discrete multicellular clusters. We show that ERK2 overexpression reduced the vertical size of lateral membranes that contain cell-cell adhesion complexes. Consequently, ERK2 overexpressing cells were unable to develop cuboidal shape, remained flat with increased spread area and intercellular adhesive contacts were present only on the basal side. Interestingly, ERK2 overexpression was not sufficient to increase phosphorylation of multiple downstream targets including transcription factors and induce global changes in gene expression, namely to increase the expression of pro-migratory transcription factor Fra1. However, ERK2 overexpression enhanced HGF/SF-induced cell scattering as these cells scattered more rapidly and to a greater extent than parental cells. Our results suggest that an increase in ERK2 expression primarily reduces cell-cell cohesion and that weakened intercellular adhesion synergizes with upstream signaling in the conversion of the multicellular epithelium into single migrating cells. This mechanism may be clinically relevant as the analysis of clinical data revealed that in one type of cancer, pancreatic adenocarcinoma, ERK2 overexpression correlates with a worse prognosis.
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Affiliation(s)
- Jan Rasl
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic; Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Josipa Grusanovic
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Zuzana Klimova
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Josef Caslavsky
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Tomas Grousl
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Jiri Novotny
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic; Department of Informatics and Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, 160 00 Prague, Czech Republic
| | - Michal Kolar
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic.
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4
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Grousl T, Vojtova J, Hasek J, Vomastek T. Yeast stress granules at a glance. Yeast 2021; 39:247-261. [PMID: 34791685 DOI: 10.1002/yea.3681] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/15/2021] [Accepted: 11/12/2021] [Indexed: 11/10/2022] Open
Abstract
The formation of stress granules (SGs), membrane-less organelles that are composed of mainly messenger ribonucleoprotein assemblies, is the result of a conserved evolutionary strategy to cellular stress. During their formation, which is triggered by robust environmental stress, SGs sequester translationally inactive mRNA molecules, which are either forwarded for further processing elsewhere or stored during a period of stress within SGs. Removal of mRNA molecules from active translation and their sequestration in SGs allows preferential translation of stress response transcripts. By affecting the specificity of mRNA translation, mRNA localization and stability, SGs are involved in the overall cellular reprogramming during periods of environmental stress and viral infection. Over the past two decades, we have learned which processes drive SGs assembly, how their composition varies under stress, and how they co-exist with other subcellular organelles. Yeast as a model has been instrumental in our understanding of SG biology. Despite the specific differences between the SGs of yeast and mammals, yeast have been shown to be a valuable tool to the study of SGs in translation-related stress response. This review summarizes the data surrounding SGs that are formed under different stress conditions in Saccharomyces cerevisiae and other yeast species. It offers a comprehensive and up-to-date view on these still somewhat mysterious entities.
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Affiliation(s)
- Tomas Grousl
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jana Vojtova
- Laboratory of Cell Reproduction, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jiri Hasek
- Laboratory of Cell Reproduction, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
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5
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Maninova M, Caslavsky J, Vomastek T. The assembly and function of perinuclear actin cap in migrating cells. Protoplasma 2017; 254:1207-1218. [PMID: 28101692 DOI: 10.1007/s00709-017-1077-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/09/2017] [Indexed: 05/24/2023]
Abstract
Stress fibers are actin bundles encompassing actin filaments, actin-crosslinking, and actin-associated proteins that represent the major contractile system in the cell. Different types of stress fibers assemble in adherent cells, and they are central to diverse cellular processes including establishment of the cell shape, morphogenesis, cell polarization, and migration. Stress fibers display specific cellular organization and localization, with ventral fibers present at the basal side, and dorsal fibers and transverse actin arcs rising at the cell front from the ventral to the dorsal side and toward the nucleus. Perinuclear actin cap fibers are a specific subtype of stress fibers that rise from the leading edge above the nucleus and terminate at the cell rear forming a dome-like structure. Perinuclear actin cap fibers are fixed at three points: both ends are anchored in focal adhesions, while the central part is physically attached to the nucleus and nuclear lamina through the linker of nucleoskeleton and cytoskeleton (LINC) complex. Here, we discuss recent work that provides new insights into the mechanism of assembly and the function of these actin stress fibers that directly link extracellular matrix and focal adhesions with the nuclear envelope.
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Affiliation(s)
- Miloslava Maninova
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic
| | - Josef Caslavsky
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic
| | - Tomas Vomastek
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic.
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6
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Vohradsky J, Panek J, Vomastek T. Numerical modelling of microRNA-mediated mRNA decay identifies novel mechanism of microRNA controlled mRNA downregulation. Nucleic Acids Res 2010; 38:4579-85. [PMID: 20371515 PMCID: PMC2919720 DOI: 10.1093/nar/gkq220] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Post-transcriptional control of mRNA by micro-RNAs (miRNAs) represents an important mechanism of gene regulation. miRNAs act by binding to the 3' untranslated region (3'UTR) of an mRNA, affecting the stability and translation of the target mRNA. Here, we present a numerical model of miRNA-mediated mRNA downregulation and its application to analysis of temporal microarray data of HepG2 cells transfected with miRNA-124a. Using the model our analysis revealed a novel mechanism of mRNA accumulation control by miRNA, predicting that specific mRNAs are controlled in a digital, switch-like manner. Specifically, the contribution of miRNAs to mRNA degradation is switched from maximum to zero in a very short period of time. Such behaviour suggests a model of control in which mRNA is at a certain moment protected from binding of miRNA and further accumulates with a basal rate. Genes associated with this process were identified and parameters of the model for all miRNA-124a affected mRNAs were computed.
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Affiliation(s)
- Jiri Vohradsky
- Institute of Microbiology ASCR vvi, Prague, Czech Republic.
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7
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Iwanicki MP, Vomastek T, Tilghman RW, Martin KH, Banerjee J, Wedegaertner PB, Parsons JT. FAK, PDZ-RhoGEF and ROCKII cooperate to regulate adhesion movement and trailing-edge retraction in fibroblasts. J Cell Sci 2008; 121:895-905. [DOI: 10.1242/jcs.020941] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
A key step in cell migration is the dynamic formation and disassembly of adhesions at the front and the concomitant movement and release of adhesions in the rear of the cell. Fibroblasts maintained in the absence of serum have stable adhesions within the rear of the cell and exhibit reduced trailing-edge retraction resulting in an elongated cell phenotype. Addition of lysophosphatidic acid (LPA) induced the movement of adhesions and retraction of the trailing edge, thus mimicking tail retraction in a migrating cell. Focal adhesion kinase (FAK), guanine nucleotide exchange factors (GEF) for Rho and the Rho effector Rho kinase II (ROCKII) are crucial for the regulation of adhesion movement and trailing-edge retraction. Downregulation of FAK by small interfering RNAs or small hairpin RNAs blocked LPA-induced adhesion movement and restoration of cell shape. This phenotype was rescued by the ectopic expression of PDZ-RhoGEF or a RhoA-effector-domain mutant that activates ROCK. Knockdown of PDZ-RhoGEF or ROCKII inhibited LPA-induced trailing-edge retraction and adhesion movement. Moreover, overexpressed PDZ-RhoGEF co-immunoprecipitated with FAK and localized to FAK-containing adhesions. These studies support a model in which FAK and PDZ-RhoGEF cooperate to induce Rho/ROCKII-dependent focal adhesion movement and trailing-edge retraction in response to LPA.
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Affiliation(s)
- Marcin P. Iwanicki
- Department of Microbiology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Tomas Vomastek
- Department of Microbiology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Robert W. Tilghman
- Department of Microbiology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Karen H. Martin
- Department of Neurobiology and Anatomy, West Virginia University, Morgantown, WV 26506, USA
| | - Jayashree Banerjee
- Departments of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Philip B. Wedegaertner
- Departments of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - J. Thomas Parsons
- Department of Microbiology, University of Virginia Health System, Charlottesville, VA 22908, USA
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8
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Vomastek T, Iwanicki MP, Schaeffer HJ, Tarcsafalvi A, Parsons JT, Weber MJ. RACK1 targets the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway to link integrin engagement with focal adhesion disassembly and cell motility. Mol Cell Biol 2007; 27:8296-305. [PMID: 17908799 PMCID: PMC2169169 DOI: 10.1128/mcb.00598-07] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The extracellular signal-regulated kinase (ERK) cascade is activated in response to a multitude of extracellular signals and converts these signals into a variety of specific biological responses, including cell differentiation, cell movement, cell division, and apoptosis. The specificity of the biological response is likely to be controlled in large measure by the localization of signaling, thus enabling ERK activity to be directed towards specific targets. Here we show that the RACK1 scaffold protein functions specifically in integrin-mediated activation of the mitogen-activated protein kinase/ERK cascade and targets active ERK to focal adhesions. We found that RACK1 associated with the core kinases of the ERK pathway, Raf, MEK, and ERK, and that attenuation of RACK1 expression resulted in a decrease in ERK activity in response to adhesion but not in response to growth factors. RACK1 silencing also caused a reduction of active ERK in focal adhesions, an increase in focal adhesion length, a decreased rate of focal adhesion disassembly, and decreased motility. Our data further suggest that focal adhesion kinase is an upstream activator of the RACK1/ERK pathway. We suggest that RACK1 tethers the ERK pathway core kinases and channels signals from upstream activation by integrins to downstream targets at focal adhesions.
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Affiliation(s)
- Tomas Vomastek
- Department of Microbiology and Cancer Center, University of Virginia Health Science Center, Charlottesville, VA 22908, USA
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9
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Kraus S, Gioeli D, Vomastek T, Gordon V, Weber MJ. Receptor for activated C kinase 1 (RACK1) and Src regulate the tyrosine phosphorylation and function of the androgen receptor. Cancer Res 2006; 66:11047-54. [PMID: 17108144 DOI: 10.1158/0008-5472.can-06-0596] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The androgen receptor (AR) remains functionally important in the development and progression of prostate cancer even when the disease seems androgen "independent." Because signal transduction by growth factor receptors increases in advanced prostate cancer and is capable of sensitizing the AR to androgen, there is considerable interest in determining the mechanisms by which signaling systems can modulate AR function. We show herein that the adaptor/scaffolding protein receptor for activated C kinase 1 (RACK1), which was previously reported to interact with the AR, modulates the tyrosine phosphorylation of AR and its interaction with the Src tyrosine kinase. We also show that down-regulation of RACK1 by short interfering RNA inhibits growth and stimulates prostate-specific antigen transcription in androgen-treated prostate cancer cells. Our results suggest that RACK1 mediates the cross-talk of AR with additional binding partners, such as Src, and facilitates the tyrosine phosphorylation and transcriptional activity of the AR.
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Affiliation(s)
- Sarah Kraus
- Department of Microbiology and Cancer Center, University of Virginia Health System, Charlottesville, Virginia, USA
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10
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Nováková L, Nádvorník R, Vomastek T, Janecek J, Branny P. Effect of phosphate on the expression of protein-Ser/Thr kinase pkg2 in Streptomyces granaticolor. Folia Microbiol (Praha) 2006; 50:503-8. [PMID: 16681148 DOI: 10.1007/bf02931438] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A time-correlated expression of eukaryotic-like protein Ser/Thr kinase Pkg2 of Streptomyces granaticolor was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR) and by transcriptional fusion experiments. In a complex medium the activity of pkg2 promoter was constant during the life cycle. Direct RNA analysis proved the presence of corresponding pkg2 transcript. S1 nuclease protection analysis of the transcription initiation site showed that pkg2 gene is expressed as a leaderless mRNA. Under phosphate starvation the promoter activity was detectable merely in the early exponential phase. Under these conditions turning off of pkg2 promoter and cessation of pkg2 transcript level coincided with the start of granaticin production.
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Affiliation(s)
- L Nováková
- Cell and Molecular Microbiology Division, Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czechia
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11
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Vomastek T, Schaeffer HJ, Tarcsafalvi A, Smolkin ME, Bissonette EA, Weber MJ. Modular construction of a signaling scaffold: MORG1 interacts with components of the ERK cascade and links ERK signaling to specific agonists. Proc Natl Acad Sci U S A 2004; 101:6981-6. [PMID: 15118098 PMCID: PMC406452 DOI: 10.1073/pnas.0305894101] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Signal transduction occurs by the reversible assembly of oligomeric protein complexes that include both enzymatic proteins and proteins without known enzymatic activity. These nonenzymatic components can serve as scaffolds or anchors and regulate the efficiency, specificity, and localization of the signaling pathway. Here we report the identification of MORG1 (mitogen-activated protein kinase organizer 1), a member of the WD-40 protein family that was isolated as a binding partner of the extracellular signal-regulated kinase (ERK) pathway scaffold protein MP1. MORG1 specifically associates with several components of the ERK pathway, including MP1, Raf-1, MEK, and ERK, and stabilizes their assembly into an oligomeric complex. MORG1 facilitates ERK activation when cells are stimulated with lysophosphatidic acid, phorbol 12-myristate 13-acetate, or serum, but not in response to epidermal growth factor. Suppression of MORG1 by short interfering RNA leads to a marked reduction in ERK activity when cells are stimulated with serum. We propose that MORG1 is a component of a modular scaffold system that participates in the regulation of agonist-specific ERK signaling.
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Affiliation(s)
- Tomas Vomastek
- Department of Microbiology and Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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12
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Kulik G, Carson JP, Vomastek T, Overman K, Gooch BD, Srinivasula S, Alnemri E, Nunez G, Weber MJ. Tumor necrosis factor alpha induces BID cleavage and bypasses antiapoptotic signals in prostate cancer LNCaP cells. Cancer Res 2001; 61:2713-9. [PMID: 11289152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Survival of cancer cells in response to therapy, immune response, or metastasis depends on interactions between pro- and antiapoptotic signals. Two major proapoptotic pathways have been described: (a) a death receptor pathway; and (b) a mitochondrial pathway. We reported previously that Akt and the epidermal growth factor (EGF) receptor send separate, redundant survival signals that act to inhibit the mitochondrial proapoptotic pathway in prostate cancer LNCaP cells. However, it was unclear at what level the pro- and antiapoptotic signals interact in these cells, and it was also unclear whether these signals would inhibit the death receptor pathway. We found that EGF can protect LNCaP cells from apoptosis induced by LY294002 but not from tumor necrosis factor a (TNF-alpha)-induced apoptosis. Furthermore, TNF-alpha induced apoptosis under conditions in which Akt was active. Treatment with TNF-alpha resulted in activation of caspase 8 and cleavage of BID, which in turn induced cytochrome c release and caspase 9-dependent activation of effector caspases. Thus, proapoptotic signals induced by both TNF-alpha and LY294002 converge on mitochondria and trigger cytochrome c release. Because EGF can inhibit cytochrome c release induced by LY294002 but not cytochrome c release induced by TNF-alpha, we suggest that the EGF survival mechanism operates on the mitochondrial pathway at a site upstream of cytochrome c release. The ability of TNF-alpha to bypass survival signals from activated EGF receptor and Akt in prostate cancer cells makes death receptor signaling a promising avenue for therapeutic intervention.
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Affiliation(s)
- G Kulik
- Department of Microbiology, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA.
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13
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Nádvorník R, Vomastek T, Janecek J, Techniková Z, Branny P. Pkg2, a novel transmembrane protein Ser/Thr kinase of Streptomyces granaticolor. J Bacteriol 1999; 181:15-23. [PMID: 9864307 PMCID: PMC103526 DOI: 10.1128/jb.181.1.15-23.1999] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/1998] [Accepted: 10/21/1998] [Indexed: 11/20/2022] Open
Abstract
A 4.2-kb SphI-BamHI fragment of chromosomal DNA from Streptomyces granaticolor was cloned and shown to encode a protein with significant sequence similarity to the eukaryotic protein serine/threonine kinases. It consists of 701 amino acids and in the N-terminal part contains all conserved catalytic domains of protein kinases. The C-terminal domain of Pkg2 contains seven tandem repeats of 11 or 12 amino acids with similarity to the tryptophan-docking motif known to stabilize a symmetrical three-dimensional structure called a propeller structure. The pkg2 gene was overexpressed in Escherichia coli, and the gene product (Pkg2) has been found to be autophosphorylated at serine and threonine residues. The N- and C-terminal parts of Pkg2 are separated with a hydrophobic stretch of 21 amino acids which translocated a PhoA fusion protein into the periplasm. Thus, Pkg2 is the first transmembrane protein serine/threonine kinase described for streptomycetes. Replacement of the pkg2 gene by the spectinomycin resistance gene resulted in changes in the morphology of aerial hyphae.
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Affiliation(s)
- R Nádvorník
- Cell and Molecular Microbiology Division, Institute of Microbiology, Czech Academy of Sciences, 142 20 Prague 4, Czech Republic
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14
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Vomastek T, Nádvorník R, Janecek J, Techniková Z, Weiser J, Branny P. Characterisation of two putative protein Ser/Thr kinases from actinomycete Streptomyces granaticolor both endowed with different properties. Eur J Biochem 1998; 257:55-61. [PMID: 9799102 DOI: 10.1046/j.1432-1327.1998.2570055.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The structural genes, pkg4 and pkg3, encoding two putative protein serine/threonine kinases in Streptomyces granaticolor, have been cloned and sequenced. The genes were isolated after screening genomic sublibraries with specific probes obtained by PCR amplification of chromosomal DNA using degenerate primers which correspond to amino acid sequences highly conserved in eukaryotic protein Ser/Thr kinases. The sequences of these genes predict polypeptide chains of 761 and 780 amino acids for Pkg4 and Pkg3, respectively. The genes are separated by only 2 bp and therefore probably constitute an operon. pkg4, which is positioned upstream of pkg3, contains a UUALeu codon suggesting a developmental-dependent mode of expression. The amino-terminal half of both proteins clearly shares similarities with the family of protein Ser/Thr kinases. Both proteins studied also possess a region rich in Pro and Ala residues and a repeating motif of 11 amino acid residues, the function of which is unknown, in the carboxy-terminal domain. Expression of pkg4 in Escherichia coli gave rise to two different forms: a soluble protein autophosphorylated at threonine residues and an insoluble form phosphorylated at threonine and serine residues. In contrast, when pkg3 was expressed in E. coli, no autophosphorylation was detected either in vivo or in vitro.
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Affiliation(s)
- T Vomastek
- Cell and Molecular Microbiology Division, Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
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15
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Abstract
The kinetics of the development of apoptosis was studied in mouse B cell hybridoma batch cultures carried out in the iron-rich protein-free medium. One of the markers of apoptosis, the apoptotic index reflecting the relative number of bodies insoluble in 6 M guanidinium hydrochloride, was found to rise significantly at 144 h, i.e., in the late stationary phase. At the decline of the culture (216 h) the value of the apoptotic index reached 29.1%. Analysis of another marker, the degree of DNA fragmentation determined on the basis of chromatographic resolution of isolated cellular DNA, revealed a significant increase as early as 96 h, i.e., at the end of the exponential phase. At 216 h the net value of the fragmented DNA fraction was about 30% of cellular DNA. The values of both markers were found to be very similar when the iron-rich protein-free supplement was replaced with conventional 10% foetal calf serum. This finding suggested that the growth factors present in the serum were not able to abolish the tendency of the hybridoma culture to undergo spontaneous apoptosis. The timing of the spontaneous onset of apoptosis in the exponential phase indicated that B cell hybridoma apoptosis was a process associated with cell proliferation and full metabolic activity rather than with the decline of cell vitality.
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Affiliation(s)
- T Vomastek
- Department of Fundamental Cytotechnology, Czechoslovak Academy of Sciences, Prague
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Franĕk F, Vomastek T, Dolníková J. Fragmented DNA and apoptotic bodies document the programmed way of cell death in hybridoma cultures. Cytotechnology 1992; 9:117-23. [PMID: 1369164 DOI: 10.1007/bf02521738] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Markers of apoptosis were followed in batch hybridoma cultures carried out in protein-free medium. Samples were collected on day 0, representing early exponential phase (viability 91%), and on day 8, corresponding to late stationary phase (viability 8%). The apoptotic index reflecting the relative number of bodies insoluble in 6 M guanidinium hydrochloride in the culture of day 8 (30%) exceeded markedly the index in the culture of day 0 (2.5%). A gel chromatography on Sepharose 2B was developed for quantitative evaluation of fragmented cellular DNA. This analysis, including a correction for nonspecific fragmentation, showed that on day 8 more than 30% of cellular DNA was fragmented, whereas on day 0 it was less than 5%. Control necrotic cells prepared by rapid killing in 1% sodium azide displayed a low apoptotic index (2.4%) and low DNA fragmentation. Electrophoretic patterns in agarose gel showed a typical "ladder" of fragments in the DNA sample of day 8. The demonstration of fragmented cellular DNA and of the high incidence of apoptotic bodies at late stationary phase adds substantial weight to the view that in hybridoma cultures apoptosis represents the prevalent mode of cell death.
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Affiliation(s)
- F Franĕk
- Department of Fundamental Cytotechnology, Czechoslovak Academy of Sciences, Praha
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