10 results on '"Melchior, Frauke"'
Search Results
2. Fasting-sensitive SUMO-switch on Prox1 controls hepatic cholesterol metabolism.
- Author
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Alfaro AJ, Dittner C, Becker J, Loft A, Mhamane A, Maida A, Georgiadi A, Tsokanos FF, Klepac K, Molocea CE, El-Merahbi R, Motzler K, Geppert J, Karikari RA, Szendrödi J, Feuchtinger A, Hofmann S, Karaca S, Urlaub H, Berriel Diaz M, Melchior F, and Herzig S
- Abstract
Accumulation of excess nutrients hampers proper liver function and is linked to nonalcoholic fatty liver disease (NAFLD) in obesity. However, the signals responsible for an impaired adaptation of hepatocytes to obesogenic dietary cues remain still largely unknown. Post-translational modification by the small ubiquitin-like modifier (SUMO) allows for a dynamic regulation of numerous processes including transcriptional reprogramming. We demonstrate that specific SUMOylation of transcription factor Prox1 represents a nutrient-sensitive determinant of hepatic fasting metabolism. Prox1 is highly SUMOylated on lysine 556 in the liver of ad libitum and refed mice, while this modification is abolished upon fasting. In the context of diet-induced obesity, Prox1 SUMOylation becomes less sensitive to fasting cues. The hepatocyte-selective knock-in of a SUMOylation-deficient Prox1 mutant into mice fed a high-fat/high-fructose diet leads to a reduction of systemic cholesterol levels, associated with the induction of liver bile acid detoxifying pathways during fasting. The generation of tools to maintain the nutrient-sensitive SUMO-switch on Prox1 may thus contribute to the development of "fasting-based" approaches for the preservation of metabolic health., (© 2023 The Authors. Published under the terms of the CC BY NC ND 4.0 license.)
- Published
- 2023
- Full Text
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3. SCF Fbxw5 targets kinesin-13 proteins to facilitate ciliogenesis.
- Author
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Schweiggert J, Habeck G, Hess S, Mikus F, Beloshistov R, Meese K, Hata S, Knobeloch KP, and Melchior F
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- Cell Cycle genetics, Humans, Protein Array Analysis, Protein Binding, Protein Interaction Mapping, SKP Cullin F-Box Protein Ligases metabolism, Ubiquitin-Protein Ligases metabolism, Cilia metabolism, F-Box Proteins metabolism, Kinesins metabolism, Organogenesis genetics
- Abstract
Microtubule depolymerases of the kinesin-13 family play important roles in various cellular processes and are frequently overexpressed in different cancer types. Despite the importance of their correct abundance, remarkably little is known about how their levels are regulated in cells. Using comprehensive screening on protein microarrays, we identified 161 candidate substrates of the multi-subunit ubiquitin E3 ligase SCF
Fbxw5 , including the kinesin-13 member Kif2c/MCAK. In vitro reconstitution assays demonstrate that MCAK and its closely related orthologs Kif2a and Kif2b become efficiently polyubiquitylated by neddylated SCFFbxw5 and Cdc34, without requiring preceding modifications. In cells, SCFFbxw5 targets MCAK for proteasomal degradation predominantly during G2 . While this seems largely dispensable for mitotic progression, loss of Fbxw5 leads to increased MCAK levels at basal bodies and impairs ciliogenesis in the following G1 /G0 , which can be rescued by concomitant knockdown of MCAK, Kif2a or Kif2b. We thus propose a novel regulatory event of ciliogenesis that begins already within the G2 phase of the preceding cell cycle., (© 2021 The Authors. Published under the terms of the CC BY 4.0 license.)- Published
- 2021
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4. Transient deSUMOylation of IRF2BP proteins controls early transcription in EGFR signaling.
- Author
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Barysch SV, Stankovic-Valentin N, Miedema T, Karaca S, Doppel J, Nait Achour T, Vasudeva A, Wolf L, Sticht C, Urlaub H, and Melchior F
- Subjects
- Carrier Proteins, Dual Specificity Phosphatase 1, ErbB Receptors genetics, Gene Expression Regulation, HeLa Cells, Humans, Nuclear Proteins, Promoter Regions, Genetic, Small Ubiquitin-Related Modifier Proteins metabolism, Ubiquitin-Protein Ligases, Signal Transduction, Sumoylation
- Abstract
Molecular switches are essential modules in signaling networks and transcriptional reprogramming. Here, we describe a role for small ubiquitin-related modifier SUMO as a molecular switch in epidermal growth factor receptor (EGFR) signaling. Using quantitative mass spectrometry, we compare the endogenous SUMO proteomes of HeLa cells before and after EGF stimulation. Thereby, we identify a small group of transcriptional coregulators including IRF2BP1, IRF2BP2, and IRF2BPL as novel players in EGFR signaling. Comparison of cells expressing wild type or SUMOylation-deficient IRF2BP1 indicates that transient deSUMOylation of IRF2BP proteins is important for appropriate expression of immediate early genes including dual specificity phosphatase 1 (DUSP1, MKP-1) and the transcription factor ATF3. We find that IRF2BP1 is a repressor, whose transient deSUMOylation on the DUSP1 promoter allows-and whose timely reSUMOylation restricts-DUSP1 transcription. Our work thus provides a paradigm how comparative SUMO proteome analyses serve to reveal novel regulators in signal transduction and transcription., (© 2021 The Authors. Published under the terms of the CC BY 4.0 license.)
- Published
- 2021
- Full Text
- View/download PDF
5. Redox regulation of SUMO enzymes is required for ATM activity and survival in oxidative stress.
- Author
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Stankovic-Valentin N, Drzewicka K, König C, Schiebel E, and Melchior F
- Subjects
- Cell Line, Cell Survival, Disulfides metabolism, Humans, Mutant Proteins genetics, Mutant Proteins metabolism, Oxidation-Reduction, Ubiquitin-Conjugating Enzymes genetics, Gene Expression Regulation, Oxidative Stress, Protein Processing, Post-Translational, Stress, Physiological, Ubiquitin-Conjugating Enzymes metabolism
- Abstract
To sense and defend against oxidative stress, cells depend on signal transduction cascades involving redox-sensitive proteins. We previously identified SUMO (small ubiquitin-related modifier) enzymes as downstream effectors of reactive oxygen species (ROS). Hydrogen peroxide transiently inactivates SUMO E1 and E2 enzymes by inducing a disulfide bond between their catalytic cysteines. How important their oxidation is in light of many other redox-regulated proteins has however been unclear. To selectively disrupt this redox switch, we identified a catalytically fully active SUMO E2 enzyme variant (Ubc9 D100A) with strongly reduced propensity to maintain a disulfide with the E1 enzyme in vitro and in cells. Replacement of Ubc9 by this variant impairs cell survival both under acute and mild chronic oxidative stresses. Intriguingly, Ubc9 D100A cells fail to maintain activity of the ATM-Chk2 DNA damage response pathway that is induced by hydrogen peroxide. In line with this, these cells are also more sensitive to the ROS-producing chemotherapeutic drugs etoposide/Vp16 and Ara-C. These findings reveal that SUMO E1~E2 oxidation is an essential redox switch in oxidative stress., (© 2016 The Authors.)
- Published
- 2016
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6. Ubiquitin-specific protease-like 1 (USPL1) is a SUMO isopeptidase with essential, non-catalytic functions.
- Author
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Schulz S, Chachami G, Kozaczkiewicz L, Winter U, Stankovic-Valentin N, Haas P, Hofmann K, Urlaub H, Ovaa H, Wittbrodt J, Meulmeester E, and Melchior F
- Subjects
- Amino Acid Sequence, Animals, Binding Sites, Catalytic Domain, Coiled Bodies metabolism, Endopeptidases chemistry, Endopeptidases genetics, HeLa Cells, Humans, Molecular Sequence Data, Mutation, Nuclear Proteins metabolism, Small Ubiquitin-Related Modifier Proteins metabolism, Ubiquitin-Specific Proteases, Zebrafish, Zebrafish Proteins chemistry, Endopeptidases metabolism, Zebrafish Proteins metabolism
- Abstract
Isopeptidases are essential regulators of protein ubiquitination and sumoylation. However, only two families of SUMO isopeptidases are at present known. Here, we report an activity-based search with the suicide inhibitor haemagglutinin (HA)-SUMO-vinylmethylester that led to the identification of a surprising new SUMO protease, ubiquitin-specific protease-like 1 (USPL1). Indeed, USPL1 neither binds nor cleaves ubiquitin, but is a potent SUMO isopeptidase both in vitro and in cells. C13orf22l--an essential but distant zebrafish homologue of USPL1--also acts on SUMO, indicating functional conservation. We have identified invariant USPL1 residues required for SUMO binding and cleavage. USPL1 is a low-abundance protein that colocalizes with coilin in Cajal bodies. Its depletion does not affect global sumoylation, but causes striking coilin mislocalization and impairs cell proliferation, functions that are not dependent on USPL1 catalytic activity. Thus, USPL1 represents a third type of SUMO protease, with essential functions in Cajal body biology.
- Published
- 2012
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7. SUMO unloads the Kap114 cab.
- Author
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Werner A and Melchior F
- Subjects
- Active Transport, Cell Nucleus, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism, Sumoylation, beta Karyopherins metabolism
- Abstract
Nucleocytoplasmic transport is an essential mechanism in all eukaryotic cells, for which the basic mechanisms seemed well understood. Transport receptors of the importin b/karyopherin family recognize, translocate and discharge cargo. Key to directed transport is the GTPase Ran, which determines compartment-specific interactions between receptors and their cargo. In this issue of The EMBO Journal, Rothenbusch et al (2012) now add a new energy-dependent event to this basic pathway by providing direct evidence that the posttranslational modification of the yeast import receptor Kap114 with small ubiquitin-related modifier (SUMO) is indispensable for its correct function. An exciting model emerges in which Kap114 sumoylation regulates Ran-dependent cargo release, and thereby acts as a mechanism for intranuclear targeting of the import cargo.
- Published
- 2012
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8. Cell biology: SUMO.
- Author
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Meulmeester E and Melchior F
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- Animals, Eukaryotic Cells metabolism, History, 20th Century, Humans, Protein Binding, Small Ubiquitin-Related Modifier Proteins history, Substrate Specificity, Viruses metabolism, Small Ubiquitin-Related Modifier Proteins metabolism
- Published
- 2008
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9. Transcription factor Sp3 is silenced through SUMO modification by PIAS1.
- Author
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Sapetschnig A, Rischitor G, Braun H, Doll A, Schergaut M, Melchior F, and Suske G
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- Animals, Base Sequence, Cell Line, DNA Primers, Drosophila melanogaster, Gene Silencing, Plasmids, Protein Inhibitors of Activated STAT, Recombinant Proteins metabolism, Sp3 Transcription Factor, Subcellular Fractions metabolism, Transfection, Zinc Fingers, DNA-Binding Proteins genetics, Proteins metabolism, SUMO-1 Protein metabolism, Transcription Factors genetics
- Abstract
Sp3 is a ubiquitous transcription factor closely related to Sp1. Here we show that Sp3 is a target for SUMO modification in vivo and in vitro. SUMO modification of Sp3 occurs at a single lysine located between the second glutamine-rich activation domain and the DNA-binding domain. Mutational analyses identified the sequence IKXE as essential for SUMO conjugation to Sp3. We identified the protein inhibitor of activated STAT1 (PIAS1) as an interaction partner of Sp3 and Ubc9. Moreover, PIAS1 strongly stimulated SUMO conjugation to Sp3, thus acting as an E3 ligase for SUMO conjugation to Sp3. All mutations that prevented SUMO modification in vitro strongly enhanced the transcriptional activity of Sp3, showing that SUMO modification silences Sp3 activity. SUMO-modified Sp3 bound to DNA with similar specificity and affinity as unmodified Sp3. However, DNA-bound Sp3 did not act as a substrate for SUMO modification.
- Published
- 2002
- Full Text
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10. The SUMO E3 ligase RanBP2 promotes modification of the HDAC4 deacetylase.
- Author
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Kirsh O, Seeler JS, Pichler A, Gast A, Müller S, Miska E, Mathieu M, Harel-Bellan A, Kouzarides T, Melchior F, and Dejean A
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- Animals, Blotting, Western, COS Cells, Cell Nucleus metabolism, Chromatin metabolism, Cytoplasm metabolism, Dimerization, Electrophoresis, Polyacrylamide Gel, Genes, Reporter, Glutathione Transferase metabolism, HeLa Cells, Humans, Lysine chemistry, Microscopy, Fluorescence, Molecular Chaperones, Mutation, Plasmids metabolism, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Signal Transduction, Transcription, Genetic, Transfection, Histone Deacetylases metabolism, Nuclear Pore Complex Proteins genetics, Nuclear Pore Complex Proteins physiology, Repressor Proteins metabolism
- Abstract
Transcriptional repression mediated through histone deacetylation is a critical component of eukaryotic gene regulation. Here we demonstrate that the class II histone deacetylase HDAC4 is covalently modified by the ubiquitin-related SUMO-1 modifier. A sumoylation-deficient point mutant (HDAC4-K559R) shows a slightly impaired ability to repress transcription as well as reduced histone deacetylase activity. The ability of HDAC4 to self-aggregate is a prerequisite for proper sumoylation in vivo. Calcium/calmodulin-dependent protein kinase (CaMK) signalling, which induces nuclear export, abrogates SUMO-1 modification of HDAC4. Moreover, the modification depends on the presence of an intact nuclear localization signal and is catalysed by the nuclear pore complex (NPC) RanBP2 protein, a factor newly identified as a SUMO E3 ligase. These findings suggest that sumoylation of HDAC4 takes place at the NPC and is coupled to its nuclear import. Finally, modification experiments indicate that the MEF2-interacting transcription repressor (MITR) as well as HDAC1 and -6 are similarly SUMO modified, indicating that sumoylation may be an important regulatory mechanism for the control of transcriptional repression mediated by both class I and II HDACs.
- Published
- 2002
- Full Text
- View/download PDF
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