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Segert J, Schneider I, Berger IM, Rottbauer W, Just S. Mediator complex subunit Med12 regulates cardiac jelly development and AV valve formation in zebrafish. Prog Biophys Mol Biol 2018; 138:20-31. [PMID: 30036562 DOI: 10.1016/j.pbiomolbio.2018.07.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/30/2018] [Accepted: 07/17/2018] [Indexed: 11/25/2022]
Abstract
The molecular mechanism essential for the formation of heart valves involves complex interactions of signaling molecules and transcription factors. The Mediator Complex (MC) functions as multi-subunit machinery to orchestrate gene transcription, especially for tissue-specific fine-tuning of transcriptional processes during development, also in the heart. Here, we analyzed the role of the MC subunit Med12 during atrioventricular canal (AVC) development and endocardial cushion formation, using the Med12-deficient zebrafish mutant trapped (tpd). Whereas primary heart formation was only slightly affected in tpd, we identified defects in AVC development and cardiac jelly formation. We found that although misexpression of bmp4 and versican in tpd hearts can be restored by overexpression of a modified version of the Sox9b transcription factor (harboring VP16 transactivation domain) that functions independent of its co-activator Med12, endocardial cushion development in tpd was not reconstituted. Interestingly, expression of tbx2b and its target hyaluronan synthase 2 (has2) - the synthase of hyaluronan (HA) in the heart - was absent in both uninjected and Sox9b-VP16 overexpressing tpd hearts. HA is a major ECM component of the cardiac jelly and required for endocardial cushion formation. Furthermore, we found secreted phosphoprotein 1 (spp1), an endocardial marker of activated AV endocardial cells, completely absent in tpd hearts, suggesting that crucial steps of the transformation of AV endocardial cells into endocardial cushions is blocked. We demonstrate that Med12 controls cardiac jelly formation Sox9-independently by regulating tbx2b and has2 expression and therefore the production of the glycosaminoglycan HA at the AVC to guarantee proper endocardial cushion development.
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Affiliation(s)
- Julia Segert
- Molecular Cardiology, Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Isabelle Schneider
- Molecular Cardiology, Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Ina M Berger
- Molecular Cardiology, Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | | | - Steffen Just
- Molecular Cardiology, Department of Internal Medicine II, University of Ulm, Ulm, Germany.
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Pott A, Bock S, Berger IM, Frese K, Dahme T, Keßler M, Rinné S, Decher N, Just S, Rottbauer W. Mutation of the Na +/K +-ATPase Atp1a1a.1 causes QT interval prolongation and bradycardia in zebrafish. J Mol Cell Cardiol 2018; 120:42-52. [PMID: 29750993 DOI: 10.1016/j.yjmcc.2018.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/24/2018] [Accepted: 05/07/2018] [Indexed: 02/01/2023]
Abstract
The genetic underpinnings that orchestrate the vertebrate heart rate are not fully understood yet, but of high clinical importance, since diseases of cardiac impulse formation and propagation are common and severe human arrhythmias. To identify novel regulators of the vertebrate heart rate, we deciphered the pathogenesis of the bradycardia in the homozygous zebrafish mutant hiphop (hip) and identified a missense-mutation (N851K) in Na+/K+-ATPase α1-subunit (atp1a1a.1). N851K affects zebrafish Na+/K+-ATPase ion transport capacity, as revealed by in vitro pump current measurements. Inhibition of the Na+/K+-ATPase in vivo indicates that hip rather acts as a hypomorph than being a null allele. Consequently, reduced Na+/K+-ATPase function leads to prolonged QT interval and refractoriness in the hip mutant heart, as shown by electrocardiogram and in vivo electrical stimulation experiments. We here demonstrate for the first time that Na+/K+-ATPase plays an essential role in heart rate regulation by prolonging myocardial repolarization.
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Affiliation(s)
- Alexander Pott
- Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Sarah Bock
- Molecular Cardiology, Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Ina M Berger
- Molecular Cardiology, Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Karen Frese
- Department of Internal Medicine III, Heidelberg University Medical Center, Heidelberg, Germany
| | - Tillman Dahme
- Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Mirjam Keßler
- Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Susanne Rinné
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Philipps-University of Marburg, Marburg, Germany
| | - Niels Decher
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Philipps-University of Marburg, Marburg, Germany
| | - Steffen Just
- Molecular Cardiology, Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany.
| | - Wolfgang Rottbauer
- Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany.
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Just S, Raphel L, Berger IM, Bühler A, Keßler M, Rottbauer W. Tbx20 Is an Essential Regulator of Embryonic Heart Growth in Zebrafish. PLoS One 2016; 11:e0167306. [PMID: 27907103 PMCID: PMC5132222 DOI: 10.1371/journal.pone.0167306] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/13/2016] [Indexed: 01/06/2023] Open
Abstract
The molecular mechanisms that regulate cardiomyocyte proliferation during embryonic heart growth are not completely deciphered yet. In a forward genetic N-ethyl-N-nitrosourea (ENU) mutagenesis screen, we identified the recessive embryonic-lethal zebrafish mutant line weiches herz (whz). Homozygous mutant whz embryos display impaired heart growth due to diminished embryonic cardiomyocyte proliferation resulting in cardiac hypoplasia and weak cardiac contraction. By positional cloning, we found in whz mutant zebrafish a missense mutation within the T-box 20 (Tbx20) transcription factor gene leading to destabilization of Tbx20 protein. Morpholino-mediated knock-down of Tbx20 in wild-type zebrafish embryos phenocopies whz, indicating that the whz phenotype is due to loss of Tbx20 function, thereby leading to significantly reduced cardiomyocyte numbers by impaired proliferation of heart muscle cells. Ectopic overexpression of wild-type Tbx20 in whz mutant embryos restored cardiomyocyte proliferation and heart growth. Interestingly, ectopic overexpression of Tbx20 in wild-type zebrafish embryos resulted, similar to the situation in the embryonic mouse heart, in significantly reduced proliferation rates of ventricular cardiomyocytes, suggesting that Tbx20 activity needs to be tightly fine-tuned to guarantee regular cardiomyocyte proliferation and embryonic heart growth in vivo.
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Affiliation(s)
- Steffen Just
- Molecular Cardiology, Department of Medicine II, University of Ulm, Ulm, Germany
- * E-mail: (SJ); (WR)
| | - Linda Raphel
- Department of Medicine II, University of Ulm, Ulm, Germany
| | - Ina M. Berger
- Molecular Cardiology, Department of Medicine II, University of Ulm, Ulm, Germany
| | - Anja Bühler
- Molecular Cardiology, Department of Medicine II, University of Ulm, Ulm, Germany
| | - Mirjam Keßler
- Department of Medicine II, University of Ulm, Ulm, Germany
| | - Wolfgang Rottbauer
- Molecular Cardiology, Department of Medicine II, University of Ulm, Ulm, Germany
- Department of Medicine II, University of Ulm, Ulm, Germany
- * E-mail: (SJ); (WR)
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Hoffmann S, Clauss S, Berger IM, Weiß B, Montalbano A, Röth R, Bucher M, Klier I, Wakili R, Seitz H, Schulze-Bahr E, Katus HA, Flachsbart F, Nebel A, Guenther SP, Bagaev E, Rottbauer W, Kääb S, Just S, Rappold GA. Coding and non-coding variants in the SHOX2 gene in patients with early-onset atrial fibrillation. Basic Res Cardiol 2016; 111:36. [PMID: 27138930 PMCID: PMC4853439 DOI: 10.1007/s00395-016-0557-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 04/18/2016] [Indexed: 11/25/2022]
Abstract
Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia with a strong genetic component. Molecular pathways involving the homeodomain transcription factor Shox2 control the development and function of the cardiac conduction system in mouse and zebrafish. Here we report the analysis of human SHOX2 as a potential susceptibility gene for early-onset AF. To identify causal variants and define the underlying mechanisms, results from 378 patients with early-onset AF before the age of 60 years were analyzed and compared to 1870 controls or reference datasets. We identified two missense mutations (p.G81E, p.H283Q), that were predicted as damaging. Transactivation studies using SHOX2 targets and phenotypic rescue experiments in zebrafish demonstrated that the p.H283Q mutation severely affects SHOX2 pacemaker function. We also demonstrate an association between a 3'UTR variant c.*28T>C of SHOX2 and AF (p = 0.00515). Patients carrying this variant present significantly longer PR intervals. Mechanistically, this variant creates a functional binding site for hsa-miR-92b-5p. Circulating hsa-miR-92b-5p plasma levels were significantly altered in AF patients carrying the 3'UTR variant (p = 0.0095). Finally, we demonstrate significantly reduced SHOX2 expression levels in right atrial appendages of AF patients compared to patients with sinus rhythm. Together, these results suggest a genetic contribution of SHOX2 in early-onset AF.
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Affiliation(s)
- Sandra Hoffmann
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, INF 366, 69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Sebastian Clauss
- Department of Medicine I, University Hospital Munich, Ludwig-Maximilians-University Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Ina M Berger
- Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Birgit Weiß
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, INF 366, 69120, Heidelberg, Germany
| | - Antonino Montalbano
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, INF 366, 69120, Heidelberg, Germany
| | - Ralph Röth
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, INF 366, 69120, Heidelberg, Germany
| | - Madeline Bucher
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, INF 366, 69120, Heidelberg, Germany
| | - Ina Klier
- Department of Medicine I, University Hospital Munich, Ludwig-Maximilians-University Munich (LMU), Munich, Germany
| | - Reza Wakili
- Department of Medicine I, University Hospital Munich, Ludwig-Maximilians-University Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Hervé Seitz
- Institut de génétique humaine (CNRS UPR 1142), Montpellier, France
| | - Eric Schulze-Bahr
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
| | - Hugo A Katus
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany.,Department of Internal Medicine III, University Hospital Heidelberg, Heidelberg, Germany
| | | | - Almut Nebel
- Institute of Clinical Molecular Biology, University of Kiel, Kiel, Germany
| | - Sabina Pw Guenther
- Department of Cardiac Surgery, University Hospital Munich, Ludwig-Maximilians-University Munich (LMU), Munich, Germany
| | - Erik Bagaev
- Department of Cardiac Surgery, University Hospital Munich, Ludwig-Maximilians-University Munich (LMU), Munich, Germany
| | | | - Stefan Kääb
- Department of Medicine I, University Hospital Munich, Ludwig-Maximilians-University Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Steffen Just
- Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Gudrun A Rappold
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, INF 366, 69120, Heidelberg, Germany. .,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany.
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Hein K, Mittler G, Cizelsky W, Kühl M, Ferrante F, Liefke R, Berger IM, Just S, Sträng JE, Kestler HA, Oswald F, Borggrefe T. Site-specific methylation of Notch1 controls the amplitude and duration of the Notch1 response. Sci Signal 2015; 8:ra30. [PMID: 25805888 DOI: 10.1126/scisignal.2005892] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Physiologically, Notch signal transduction plays a pivotal role in differentiation; pathologically, Notch signaling contributes to the development of cancer. Transcriptional activation of Notch target genes involves cleavage of the Notch receptor in response to ligand binding, production of the Notch intracellular domain (NICD), and NICD migration into the nucleus and assembly of a coactivator complex. Posttranslational modifications of the NICD are important for its transcriptional activity and protein turnover. Deregulation of Notch signaling and stabilizing mutations of Notch1 have been linked to leukemia development. We found that the methyltransferase CARM1 (coactivator-associated arginine methyltransferase 1; also known as PRMT4) methylated NICD at five conserved arginine residues within the C-terminal transactivation domain. CARM1 physically and functionally interacted with the NICD-coactivator complex and was found at gene enhancers in a Notch-dependent manner. Although a methylation-defective NICD mutant was biochemically more stable, this mutant was biologically less active as measured with Notch assays in embryos of Xenopus laevis and Danio rerio. Mathematical modeling indicated that full but short and transient Notch signaling required methylation of NICD.
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Affiliation(s)
- Kerstin Hein
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany. Institute of Biochemistry, University of Giessen, 35392 Giessen, Germany
| | - Gerhard Mittler
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany. BIOSS, Center for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 18, 79104 Freiburg, Germany
| | - Wiebke Cizelsky
- Institute for Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Michael Kühl
- Institute for Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Francesca Ferrante
- Institute of Biochemistry, University of Giessen, 35392 Giessen, Germany
| | - Robert Liefke
- Department of Cell Biology, Harvard Medical School and Division of Newborn Medicine, Boston Children's Hospital, Boston, MA 02215, USA
| | - Ina M Berger
- Department of Internal Medicine II, Center for Internal Medicine, University Medical Center Ulm, 89081 Ulm, Germany
| | - Steffen Just
- Department of Internal Medicine II, Center for Internal Medicine, University Medical Center Ulm, 89081 Ulm, Germany
| | - J Eric Sträng
- Core Unit Medical Systems Biology, Institute of Neural Information Processing, Ulm University, 89069 Ulm, Germany
| | - Hans A Kestler
- Core Unit Medical Systems Biology, Institute of Neural Information Processing, Ulm University, 89069 Ulm, Germany. Friedrich-Schiller University and Fritz Lipmann Institute, Leibniz Institute for Aging Research, D-07745 Jena, Germany
| | - Franz Oswald
- Department of Internal Medicine I, Center for Internal Medicine, University Medical Center Ulm, 89081 Ulm, Germany.
| | - Tilman Borggrefe
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany. Institute of Biochemistry, University of Giessen, 35392 Giessen, Germany.
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Philipp M, Berger IM, Just S, Caron MG. Overlapping and opposing functions of G protein-coupled receptor kinase 2 (GRK2) and GRK5 during heart development. J Biol Chem 2014; 289:26119-26130. [PMID: 25104355 DOI: 10.1074/jbc.m114.551952] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
G protein-coupled receptor kinases 2 (GRK2) and 5 (GRK5) are fundamental regulators of cardiac performance in adults but are less well characterized for their function in the hearts of embryos. GRK2 and -5 belong to different subfamilies and function as competitors in the control of certain receptors and signaling pathways. In this study, we used zebrafish to investigate whether the fish homologs of GRK2 and -5, Grk2/3 and Grk5, also have unique, complementary, or competitive roles during heart development. We found that they differentially regulate the heart rate of early embryos and equally facilitate heart function in older embryos and that both are required to develop proper cardiac morphology. A loss of Grk2/3 results in dilated atria and hypoplastic ventricles, and the hearts of embryos depleted in Grk5 present with a generalized atrophy. This Grk5 morphant phenotype was associated with an overall decrease of early cardiac progenitors as well as a reduction in the area occupied by myocardial progenitor cells. In the case of Grk2/3, the progenitor decrease was confined to a subset of precursor cells with a committed ventricular fate. We attempted to rescue the GRK loss-of-function heart phenotypes by downstream activation of Hedgehog signaling. The Grk2/3 loss-of-function embryos were rescued by this approach, but Grk5 embryos failed to respond. In summary, we found that GRK2 and GRK5 control cardiac function as well as morphogenesis during development although with different morphological outcomes.
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Affiliation(s)
- Melanie Philipp
- Institute of Biochemistry and Molecular Biology and Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | - Ina M Berger
- Department of Internal Medicine II-Cardiology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany and
| | - Steffen Just
- Department of Internal Medicine II-Cardiology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany and
| | - Marc G Caron
- Departments of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710; Departments of Medicine, and Duke University Medical Center, Durham, North Carolina 27710; Departments of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710
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Spaich S, Will RD, Just S, Spaich S, Kuhn C, Frank D, Berger IM, Wiemann S, Korn B, Koegl M, Backs J, Katus HA, Rottbauer W, Frey N. F-box and leucine-rich repeat protein 22 is a cardiac-enriched F-box protein that regulates sarcomeric protein turnover and is essential for maintenance of contractile function in vivo. Circ Res 2012; 111:1504-16. [PMID: 22972877 DOI: 10.1161/circresaha.112.271007] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE The emerging role of the ubiquitin-proteasome system in cardiomyocyte function and homeostasis implies the necessity of tight regulation of protein degradation. However, little is known about cardiac components of this machinery. OBJECTIVE We sought to determine whether molecules exist that control turnover of cardiac-specific proteins. METHODS AND RESULTS Using a bioinformatic approach to identify novel cardiac-enriched sarcomere proteins, we identified F-box and leucine-rich repeat protein 22 (Fbxl22). Tissue-specific expression was confirmed by multiple tissue Northern and Western Blot analyses as well as quantitative reverse-transcriptase polymerase chain reaction on a human cDNA library. Immunocolocalization experiments in neonatal and adult rat ventricular cardiomyocytes as well as murine heart tissue located Fbxl22 to the sarcomeric z-disc. To detect cardiac protein interaction partners, we performed a yeast 2-hybrid screen using Fbxl22 as bait. Coimmunoprecipitation confirmed the identified interactions of Fbxl22 with S-phase kinase-associated protein 1 and Cullin1, 2 critical components of SCF (Skp1/Cul1/F-box) E3- ligases. Moreover, we identified several potential substrates, including the z-disc proteins α-actinin and filamin C. Consistently, in vitro overexpression of Fbxl22-mediated degradation of both substrates in a dose-dependent fashion, whereas proteasome inhibition with MG-132 markedly attenuated degradation of both α-actinin and filamin C. Finally, targeted knockdown of Fbxl22 in rat cardiomyocytes as well as zebrafish embryos results in the accumulation of α-actinin associated with severely impaired contractile function and cardiomyopathy in vivo. CONCLUSIONS These findings reveal the previously uncharacterized cardiac-specific F-box protein Fbxl22 as a component of a novel cardiac E3 ligase. Fbxl22 promotes the proteasome-dependent degradation of key sarcomeric proteins, such as α-actinin and filamin C, and is essential for maintenance of normal contractile function in vivo.
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Affiliation(s)
- Sebastian Spaich
- Department of Internal Medicine III, University of Heidelberg, Heidelberg, Germany
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Just S, Meder B, Berger IM, Etard C, Trano N, Patzel E, Hassel D, Marquart S, Dahme T, Vogel B, Fishman MC, Katus HA, Strähle U, Rottbauer W. The myosin-interacting protein SMYD1 is essential for sarcomere organization. Development 2011. [DOI: 10.1242/dev.73957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Just S, Meder B, Berger IM, Etard C, Trano N, Patzel E, Hassel D, Marquart S, Dahme T, Vogel B, Fishman MC, Katus HA, Strähle U, Rottbauer W. The myosin-interacting protein SMYD1 is essential for sarcomere organization. J Cell Sci 2011; 124:3127-36. [PMID: 21852424 DOI: 10.1242/jcs.084772] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
Assembly, maintenance and renewal of sarcomeres require highly organized and balanced folding, transport, modification and degradation of sarcomeric proteins. However, the molecules that mediate these processes are largely unknown. Here, we isolated the zebrafish mutant flatline (fla), which shows disturbed sarcomere assembly exclusively in heart and fast-twitch skeletal muscle. By positional cloning we identified a nonsense mutation within the SET- and MYND-domain-containing protein 1 gene (smyd1) to be responsible for the fla phenotype. We found SMYD1 expression to be restricted to the heart and fast-twitch skeletal muscle cells. Within these cell types, SMYD1 localizes to both the sarcomeric M-line, where it physically associates with myosin, and the nucleus, where it supposedly represses transcription through its SET and MYND domains. However, although we found transcript levels of thick filament chaperones, such as Hsp90a1 and UNC-45b, to be severely upregulated in fla, its histone methyltransferase activity - mainly responsible for the nuclear function of SMYD1 - is dispensable for sarcomerogenesis. Accordingly, sarcomere assembly in fla mutant embryos can be reconstituted by ectopically expressing histone methyltransferase-deficient SMYD1. By contrast, ectopic expression of myosin-binding-deficient SMYD1 does not rescue fla mutants, implicating an essential role for the SMYD1-myosin interaction in cardiac and fast-twitch skeletal muscle thick filament assembly.
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Affiliation(s)
- Steffen Just
- Department of Medicine II, University of Ulm, 89081 Ulm, Germany
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Just S, Berger IM, Meder B, Backs J, Keller A, Marquart S, Frese K, Patzel E, Rauch GJ, Katus HA, Rottbauer W. Protein kinase D2 controls cardiac valve formation in zebrafish by regulating histone deacetylase 5 activity. Circulation 2011; 124:324-34. [PMID: 21730303 DOI: 10.1161/circulationaha.110.003301] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND The molecular mechanisms that guide heart valve formation are not well understood. However, elucidation of the genetic basis of congenital heart disease is one of the prerequisites for the development of tissue-engineered heart valves. METHODS AND RESULTS We isolated here a mutation in zebrafish, bungee (bng(jh177)), which selectively perturbs valve formation in the embryonic heart by abrogating endocardial Notch signaling in cardiac cushions. We found by positional cloning that the bng phenotype is caused by a missense mutation (Y849N) in zebrafish protein kinase D2 (pkd2). The bng mutation selectively impairs PKD2 kinase activity and hence Histone deacetylase 5 phosphorylation, nuclear export, and inactivation. As a result, the expression of Histone deacetylase 5 target genes Krüppel-like factor 2a and 4a, transcription factors known to be pivotal for heart valve formation and to act upstream of Notch signaling, is severely downregulated in bungee (bng) mutant embryos. Accordingly, the expression of Notch target genes, such as Hey1, Hey2, and HeyL, is severely decreased in bng mutant embryos. Remarkably, downregulation of Histone deacetylase 5 activity in homozygous bng mutant embryos can rescue the mutant phenotype and reconstitutes notch1b expression in atrioventricular endocardial cells. CONCLUSIONS We demonstrate for the first time that proper heart valve formation critically depends on Protein kinase D2-Histone deacetylase 5-Krüppel-like factor signaling.
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Affiliation(s)
- Steffen Just
- Department of Medicine II, University of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany
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Meder B, Scholz EP, Hassel D, Wolff C, Just S, Berger IM, Patzel E, Karle C, Katus HA, Rottbauer W. Reconstitution of defective protein trafficking rescues Long-QT syndrome in zebrafish. Biochem Biophys Res Commun 2011; 408:218-24. [DOI: 10.1016/j.bbrc.2011.03.121] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 03/26/2011] [Indexed: 11/25/2022]
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Notari MA, Mittler BE, Travisano V, Berger IM. Fibromatosis of the plantar aspect of the hallux. A case report. J Am Podiatry Assoc 1984; 74:298-9. [PMID: 6747193 DOI: 10.7547/87507315-74-6-298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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