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Kagiwada S, Aramaki S, Wu G, Shin B, Kutejova E, Obridge D, Adachi K, Wrana JL, Hübner K, Schöler HR. YAP establishes epiblast responsiveness to inductive signals for germ cell fate. Development 2021; 148:272520. [PMID: 34528691 PMCID: PMC8571999 DOI: 10.1242/dev.199732] [Citation(s) in RCA: 3] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 09/09/2021] [Indexed: 12/14/2022]
Abstract
The germ cell lineage in mammals is induced by the stimulation of pluripotent epiblast cells by signaling molecules. Previous studies have suggested that the germ cell differentiation competence or responsiveness of epiblast cells to signaling molecules is established and maintained in epiblast cells of a specific differentiation state. However, the molecular mechanism underlying this process has not been well defined. Here, using the differentiation model of mouse epiblast stem cells (EpiSCs), we have shown that two defined EpiSC lines have robust germ cell differentiation competence. However, another defined EpiSC line has no competence. By evaluating the molecular basis of EpiSCs with distinct germ cell differentiation competence, we identified YAP, an intracellular mediator of the Hippo signaling pathway, as crucial for the establishment of germ cell induction. Strikingly, deletion of YAP severely affected responsiveness to inductive stimuli, leading to a defect in WNT target activation and germ cell differentiation. In conclusion, we propose that the Hippo/YAP signaling pathway creates a potential for germ cell fate induction via mesodermal WNT signaling in pluripotent epiblast cells. Summary: YAP, an intracellular mediator of the Hippo signaling pathway, establishes epiblast competency for germ cell differentiation through activation of the WNT pathway.
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Affiliation(s)
- Saya Kagiwada
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany
| | - Shinya Aramaki
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany
| | - Guangming Wu
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany.,Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Luoxuan Avenue, Haizhu District, 510320 Guangzhou, PRC
| | - Borami Shin
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany
| | - Eva Kutejova
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany
| | - David Obridge
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany
| | - Kenjiro Adachi
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany
| | - Jeffrey L Wrana
- Department of Cancer Biology, Centre for Systems Biology, Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Karin Hübner
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany
| | - Hans R Schöler
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster 48149, Germany.,Medical Faculty, University of Münster, Münster 48149, Germany
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2
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Aramaki S, Kagiwada S, Wu G, Obridge D, Adachi K, Kutejova E, Lickert H, Hübner K, Schöler HR. Residual pluripotency is required for inductive germ cell segregation. EMBO Rep 2021; 22:e52553. [PMID: 34156139 PMCID: PMC8344911 DOI: 10.15252/embr.202152553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/25/2021] [Accepted: 05/27/2021] [Indexed: 12/31/2022] Open
Abstract
Fine‐tuned dissolution of pluripotency is critical for proper cell differentiation. Here we show that the mesodermal transcription factor, T, globally affects the properties of pluripotency through binding to Oct4 and to the loci of other pluripotency regulators. Strikingly, lower T levels coordinately affect naïve pluripotency, thereby directly activating the germ cell differentiation program, in contrast to the induction of germ cell fate of primed models. Contrary to the effect of lower T levels, higher T levels more severely affect the pluripotency state, concomitantly enhancing the somatic differentiation program and repressing the germ cell differentiation program. Consistent with such in vitro findings, nascent germ cells in vivo are detected in the region of lower T levels at the posterior primitive streak. Furthermore, T and core pluripotency regulators co‐localize at the loci of multiple germ cell determinants responsible for germ cell development. In conclusion, our findings indicate that residual pluripotency establishes the earliest and fundamental regulatory mechanism for inductive germline segregation from somatic lineages.
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Affiliation(s)
- Shinya Aramaki
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Saya Kagiwada
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Guangming Wu
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - David Obridge
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Kenjiro Adachi
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Eva Kutejova
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Heiko Lickert
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Neuherberg, Germany
| | - Karin Hübner
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Hans R Schöler
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Medical Faculty, University of Münster, Münster, Germany
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3
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Zwirzitz A, Reiter M, Skrabana R, Ohradanova-Repic A, Majdic O, Gutekova M, Cehlar O, Petrovčíková E, Kutejova E, Stanek G, Stockinger H, Leksa V. Lactoferrin is a natural inhibitor of plasminogen activation. J Biol Chem 2018; 293:8600-8613. [PMID: 29669808 DOI: 10.1074/jbc.ra118.003145] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [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: 03/26/2018] [Revised: 04/07/2018] [Indexed: 12/31/2022] Open
Abstract
The plasminogen system is essential for dissolution of fibrin clots, and in addition, it is involved in a wide variety of other physiological processes, including proteolytic activation of growth factors, cell migration, and removal of protein aggregates. On the other hand, uncontrolled plasminogen activation contributes to many pathological processes (e.g. tumor cells' invasion in cancer progression). Moreover, some virulent bacterial species (e.g. Streptococci or Borrelia) bind human plasminogen and hijack the host's plasminogen system to penetrate tissue barriers. Thus, the conversion of plasminogen to the active serine protease plasmin must be tightly regulated. Here, we show that human lactoferrin, an iron-binding milk glycoprotein, blocks plasminogen activation on the cell surface by direct binding to human plasminogen. We mapped the mutual binding sites to the N-terminal region of lactoferrin, encompassed also in the bioactive peptide lactoferricin, and kringle 5 of plasminogen. Finally, lactoferrin blocked tumor cell invasion in vitro and also plasminogen activation driven by Borrelia Our results explain many diverse biological properties of lactoferrin and also suggest that lactoferrin may be useful as a potential tool for therapeutic interventions to prevent both invasive malignant cells and virulent bacteria from penetrating host tissues.
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Affiliation(s)
| | - Michael Reiter
- From the Institute for Hygiene and Applied Immunology and
| | - Rostislav Skrabana
- the Laboratory of Structural Biology of Neurodegeneration, Institute of Neuroimmunology, and
| | | | - Otto Majdic
- Institute of Immunology, Center for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Marianna Gutekova
- the Laboratory of Molecular Immunology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava 814 38, Slovak Republic
| | - Ondrej Cehlar
- the Laboratory of Structural Biology of Neurodegeneration, Institute of Neuroimmunology, and
| | - Eva Petrovčíková
- the Laboratory of Molecular Immunology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava 814 38, Slovak Republic
| | - Eva Kutejova
- the Laboratory of Molecular Immunology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava 814 38, Slovak Republic
| | - Gerold Stanek
- From the Institute for Hygiene and Applied Immunology and
| | | | - Vladimir Leksa
- From the Institute for Hygiene and Applied Immunology and .,the Laboratory of Molecular Immunology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava 814 38, Slovak Republic
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4
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Kutejova E, Sasai N, Shah A, Gouti M, Briscoe J. Neural Progenitors Adopt Specific Identities by Directly Repressing All Alternative Progenitor Transcriptional Programs. Dev Cell 2016; 36:639-53. [PMID: 26972603 PMCID: PMC4819439 DOI: 10.1016/j.devcel.2016.02.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [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] [Received: 11/05/2015] [Revised: 12/29/2015] [Accepted: 02/12/2016] [Indexed: 01/01/2023]
Abstract
In the vertebrate neural tube, a morphogen-induced transcriptional network produces multiple molecularly distinct progenitor domains, each generating different neuronal subtypes. Using an in vitro differentiation system, we defined gene expression signatures of distinct progenitor populations and identified direct gene-regulatory inputs corresponding to locations of specific transcription factor binding. Combined with targeted perturbations of the network, this revealed a mechanism in which a progenitor identity is installed by active repression of the entire transcriptional programs of other neural progenitor fates. In the ventral neural tube, sonic hedgehog (Shh) signaling, together with broadly expressed transcriptional activators, concurrently activates the gene expression programs of several domains. The specific outcome is selected by repressive input provided by Shh-induced transcription factors that act as the key nodes in the network, enabling progenitors to adopt a single definitive identity from several initially permitted options. Together, the data suggest design principles relevant to many developing tissues. Specific vertebrate neural progenitor populations generated in vitro Gene expression dynamics, transcription factor binding assessed in neural progenitors Progenitor fate selected by repressors blocking entire programs of other identities Repressors counteract non-selective morphogen and pan-neural activatory inputs
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Affiliation(s)
- Eva Kutejova
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Noriaki Sasai
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Ankita Shah
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Mina Gouti
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - James Briscoe
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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5
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Novotna J, Olsovska J, Novak P, Mojzes P, Chaloupkova R, Kamenik Z, Spizek J, Kutejova E, Mareckova M, Tichy P, Damborsky J, Janata J. Lincomycin biosynthesis involves a tyrosine hydroxylating heme protein of an unusual enzyme family. PLoS One 2013; 8:e79974. [PMID: 24324587 PMCID: PMC3851162 DOI: 10.1371/journal.pone.0079974] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 10/07/2013] [Indexed: 11/18/2022] Open
Abstract
The gene lmbB2 of the lincomycin biosynthetic gene cluster of Streptomyces lincolnensis ATCC 25466 was shown to code for an unusual tyrosine hydroxylating enzyme involved in the biosynthetic pathway of this clinically important antibiotic. LmbB2 was expressed in Escherichia coli, purified near to homogeneity and shown to convert tyrosine to 3,4-dihydroxyphenylalanine (DOPA). In contrast to the well-known tyrosine hydroxylases (EC 1.14.16.2) and tyrosinases (EC 1.14.18.1), LmbB2 was identified as a heme protein. Mass spectrometry and Soret band-excited Raman spectroscopy of LmbB2 showed that LmbB2 contains heme b as prosthetic group. The CO-reduced differential absorption spectra of LmbB2 showed that the coordination of Fe was different from that of cytochrome P450 enzymes. LmbB2 exhibits sequence similarity to Orf13 of the anthramycin biosynthetic gene cluster, which has recently been classified as a heme peroxidase. Tyrosine hydroxylating activity of LmbB2 yielding DOPA in the presence of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4) was also observed. Reaction mechanism of this unique heme peroxidases family is discussed. Also, tyrosine hydroxylation was confirmed as the first step of the amino acid branch of the lincomycin biosynthesis.
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Affiliation(s)
- Jitka Novotna
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Central-European Technology Institute, Brno, Czech Republic
- Crop Research Institute, Drnovska Prague, Czech Republic
| | - Jana Olsovska
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Petr Novak
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Peter Mojzes
- Institute of Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - Radka Chaloupkova
- Loschmidt Laboratories, Institute of Experimental Biology and National Centre for Biomolecular Research, Brno, Czech Republic
| | - Zdenek Kamenik
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jaroslav Spizek
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Eva Kutejova
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | | | - Pavel Tichy
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jiri Damborsky
- Loschmidt Laboratories, Institute of Experimental Biology and National Centre for Biomolecular Research, Brno, Czech Republic
| | - Jiri Janata
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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6
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Donaldson IJ, Amin S, Hensman JJ, Kutejova E, Rattray M, Lawrence N, Hayes A, Ward CM, Bobola N. Genome-wide occupancy links Hoxa2 to Wnt-β-catenin signaling in mouse embryonic development. Nucleic Acids Res 2012; 40:3990-4001. [PMID: 22223247 PMCID: PMC3351182 DOI: 10.1093/nar/gkr1240] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [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: 01/07/2023] Open
Abstract
The regulation of gene expression is central to developmental programs and largely depends on the binding of sequence-specific transcription factors with cis-regulatory elements in the genome. Hox transcription factors specify the spatial coordinates of the body axis in all animals with bilateral symmetry, but a detailed knowledge of their molecular function in instructing cell fates is lacking. Here, we used chromatin immunoprecipitation with massively parallel sequencing (ChIP-seq) to identify Hoxa2 genomic locations in a time and space when it is actively instructing embryonic development in mouse. Our data reveals that Hoxa2 has large genome coverage and potentially regulates thousands of genes. Sequence analysis of Hoxa2-bound regions identifies high occurrence of two main classes of motifs, corresponding to Hox and Pbx-Hox recognition sequences. Examination of the binding targets of Hoxa2 faithfully captures the processes regulated by Hoxa2 during embryonic development; in addition, it uncovers a large cluster of potential targets involved in the Wnt-signaling pathway. In vivo examination of canonical Wnt-β-catenin signaling reveals activity specifically in Hoxa2 domain of expression, and this is undetectable in Hoxa2 mutant embryos. The comprehensive mapping of Hoxa2-binding sites provides a framework to study Hox regulatory networks in vertebrate developmental processes.
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Affiliation(s)
- Ian J Donaldson
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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7
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Cruz C, Ribes V, Kutejova E, Cayuso J, Lawson V, Norris D, Stevens J, Davey M, Blight K, Bangs F, Mynett A, Hirst E, Chung R, Balaskas N, Brody SL, Marti E, Briscoe J. Foxj1 regulates floor plate cilia architecture and modifies the response of cells to sonic hedgehog signalling. Development 2010; 137:4271-82. [PMID: 21098568 PMCID: PMC2990214 DOI: 10.1242/dev.051714] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [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] [Accepted: 09/30/2010] [Indexed: 01/24/2023]
Abstract
Sonic hedgehog signalling is essential for the embryonic development of many tissues including the central nervous system, where it controls the pattern of cellular differentiation. A genome-wide screen of neural progenitor cells to evaluate the Shh signalling-regulated transcriptome identified the forkhead transcription factor Foxj1. In both chick and mouse Foxj1 is expressed in the ventral midline of the neural tube in cells that make up the floor plate. Consistent with the role of Foxj1 in the formation of long motile cilia, floor plate cells produce cilia that are longer than the primary cilia found elsewhere in the neural tube, and forced expression of Foxj1 in neuroepithelial cells is sufficient to increase cilia length. In addition, the expression of Foxj1 in the neural tube and in an Shh-responsive cell line attenuates intracellular signalling by decreasing the activity of Gli proteins, the transcriptional mediators of Shh signalling. We show that this function of Foxj1 depends on cilia. Nevertheless, floor plate identity and ciliogenesis are unaffected in mouse embryos lacking Foxj1 and we provide evidence that additional transcription factors expressed in the floor plate share overlapping functions with Foxj1. Together, these findings identify a novel mechanism that modifies the cellular response to Shh signalling and reveal morphological and functional features of the amniote floor plate that distinguish these cells from the rest of the neuroepithelium.
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Affiliation(s)
- Catarina Cruz
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
- Programa Doutoral em Biologia Experimental e Biomedicina, Department of Zoology, Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3004-517, Portugal
| | - Vanessa Ribes
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Eva Kutejova
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Jordi Cayuso
- Instituto de Biología Molecular de Barcelona, CSIC, Parc Científic de Barcelona, C/Josep Samitier 1-5, Barcelona, 08028, Spain
| | - Victoria Lawson
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | | | | | - Megan Davey
- Division of Genetics and Genomics, Roslin Institute, Roslin, EH25 9PS, UK
| | - Ken Blight
- Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Fiona Bangs
- Biology and Biochemistry Department, University of Bath, Bath BA2 7AY, UK
| | - Anita Mynett
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Elizabeth Hirst
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Rachel Chung
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Nikolaos Balaskas
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Steven L. Brody
- Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Elisa Marti
- Instituto de Biología Molecular de Barcelona, CSIC, Parc Científic de Barcelona, C/Josep Samitier 1-5, Barcelona, 08028, Spain
| | - James Briscoe
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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8
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Dvoráková-Holá K, Matusková A, Kubala M, Otyepka M, Kucera T, Vecer J, Herman P, Parkhomenko N, Kutejova E, Janata J. Glycine-rich loop of mitochondrial processing peptidase alpha-subunit is responsible for substrate recognition by a mechanism analogous to mitochondrial receptor Tom20. J Mol Biol 2010; 396:1197-210. [PMID: 20053354 DOI: 10.1016/j.jmb.2009.12.054] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [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: 06/19/2009] [Revised: 12/23/2009] [Accepted: 12/28/2009] [Indexed: 02/07/2023]
Abstract
Tryptophan fluorescence measurements were used to characterize the local dynamics of the highly conserved glycine-rich loop (GRL) of the mitochondrial processing peptidase (MPP) alpha-subunit in the presence of the substrate precursor. Reporter tryptophan residue was introduced into the GRL of the yeast alpha-MPP (Y299W) or at a proximal site (Y303W). Time-resolved and steady-state fluorescence spectroscopy demonstrated that for Trp299, the primary contact with the yeast malate dehydrogenase precursor evokes a change of the local GRL mobility. Moreover, time-resolved measurements showed that a functionless alpha-MPP with a single-residue deletion in the loop (Y303W/DeltaG292) is defective particularly in the primary contact with substrate. Thus, the GRL was proved to be part of a contact site of the enzyme specifically recognizing the substrate. Regarding the surface exposure and presence of the hydrophobic patches within the GRL, we proposed a functional analogy between the presequence recognition by the hydrophobic binding groove of the Tom20 mitochondrial import receptor and the GRL of the alpha-MPP. A molecular dynamics (MD) simulation of the MPP-substrate peptide complex model was employed to test this hypothesis. The initial positioning and conformation of the substrate peptide in the model fitting were chosen based on the analogy of its interaction with the Tom20 binding groove. MD simulation confirmed the stability of the proposed interaction and showed also a decrease in GRL flexibility in the presence of substrate, in agreement with fluorescence measurements. Moreover, conserved substrate hydrophobic residues in positions +1 and -4 to the cleavage site remain in close contact with the side chains of the GRL during the entire production part of MD simulation as stabilizing points of the hydrophobic interaction. We conclude that the GRL of the MPP alpha-subunit is the crucial evolutional outcome of the presequence recognition by MPP and represents a functional parallel with Tom20 import receptor.
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Affiliation(s)
- Klára Dvoráková-Holá
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic
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9
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Abstract
Hox transcription factors control morphogenesis along the head-tail axis of bilaterians. Because their direct functional targets are still poorly understood in vertebrates, it remains unclear how the positional information encoded by Hox genes is translated into morphogenetic changes. Here, we conclusively demonstrate that Six2 is a direct downstream target of Hoxa2 in vivo and show that the ectopic expression of Six2, observed in the absence of Hoxa2, contributes to the Hoxa2 mouse mutant phenotype. We propose that Six2 acts to mediate Hoxa2 control over the insulin-like growth factor pathway during branchial arch development.
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Affiliation(s)
- Eva Kutejova
- Department of Developmental Biology, Max-Planck Institute of Immunobiology, Freiburg, Germany
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10
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Abstract
The Hoxa2 transcription factor acts during development of the second branchial arch. As for most of the developmental processes controlled by Hox proteins, the mechanism by which Hoxa2 regulates the morphology of second branchial arch derivatives is unclear. We show that Six2, another transcription factor, is genetically downstream of Hoxa2. High levels of Six2 are observed in the Hoxa2 loss-of-function mutant. By using a transgenic approach to overexpress Six2 in the embryonic area controlled by Hoxa2, we observed a phenotype that is reminiscent of the Hoxa2 mutant phenotype. Furthermore, we demonstrate that Hoxa2 regulation of Six2 is confined to a 0.9 kb fragment of the Six2 promoter and that Hoxa2 binds to this promoter region. These results strongly suggest that Six2 is a direct target of Hoxa2.
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Affiliation(s)
- Eva Kutejova
- Department of Developmental Biology, Max-Planck Institute of Immunobiology, Stuebeweg 51, 79108 Freiburg, Germany
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11
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Golubnitchaya-Labudova O, Horecka T, Kapalla M, Perecko D, Kutejova E, Lubec G. Thioredoxin from Streptomyces aureofaciens controls coiling of plasmid DNA. Life Sci 1998; 62:397-412. [PMID: 9449230 DOI: 10.1016/s0024-3205(97)01133-8] [Citation(s) in RCA: 3] [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: 02/05/2023]
Abstract
A number of potential functions of thioredoxin have been proposed in literature, including a role for DNA replication. The aim of our study was to investigate the effects of thioredoxin from Streptomyces aureofaciens (Trx S.a.) on plasmid DNA. Trx S.a. was incubated with plasmid forms and the incubation product(s) characterized on agarose gels. To compare Trx activity with enzymes with known DNA modifying activities, topoisomerase I, II (gyrase) and T4 DNA ligase were incubated with plasmid DNA in parallel. For the demonstration of nick removal a PCR technique was used. Trx S.a. bound non-specifically to plasmid DNA relaxing supercoiled circle closed form (CCC form) with subsequent formation of the circle closed form (CC form) as a major product. The amplification of a specific DNA template, possible only after nick removal, took place following incubation with Trx. The effect of topoisomerase I on plasmid DNA resembled Trx S.a. activity. We propose the following mechanism for CCC relaxation: Binding of Trx leads to a break of one strand and CC is formed by stepwise relaxation, ending with nick removal. The concomitant finding of open circle form (OC form) generation after incubation with Trx may indicate the generation of an intermediate due to the postulated strand break at initiation. This control of coiling may play a role in the DNA replication machinery, providing CC as a readily available substrate for DNA polymerases. In addition, Trx may serve in DNA repair mechanisms by its nonspecific binding to DNA and nick removing activity.
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