The Experts below are selected from a list of 12924 Experts worldwide ranked by ideXlab platform
Frank L. Conlon - One of the best experts on this subject based on the ideXlab platform.
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Formation of a TBX20-CASZ1 protein complex is protective against dilated cardiomyopathy and critical for cardiac homeostasis.
PLoS genetics, 2017Co-Authors: Leslie M. Kennedy, Erin Kaltenbrun, Todd M. Greco, Ileana M. Cristea, Brenda Temple, Laura E. Herring, Frank L. ConlonAbstract:By the age of 40, one in five adults without symptoms of cardiovascular disease are at risk for developing congestive heart failure. Within this population, dilated cardiomyopathy (DCM) remains one of the leading causes of disease and death, with nearly half of cases genetically determined. Though genetic and high throughput sequencing-based approaches have identified sporadic and inherited mutations in a multitude of genes implicated in cardiomyopathy, how combinations of asymptomatic mutations lead to cardiac failure remains a mystery. Since a number of studies have implicated mutations of the transcription factor TBX20 in congenital heart diseases, we investigated the underlying mechanisms, using an unbiased systems-based screen to identify novel, cardiac-specific binding partners. We demonstrated that TBX20 physically and genetically interacts with the essential transcription factor CASZ1. This interaction is required for survival, as mice heterozygous for both TBX20 and Casz1 die post-natally as a result of DCM. A TBX20 mutation associated with human familial DCM sterically interferes with the TBX20-CASZ1 interaction and provides a physical basis for how this human mutation disrupts normal cardiac function. Finally, we employed quantitative proteomic analyses to define the molecular pathways mis-regulated upon disruption of this novel complex. Collectively, our proteomic, biochemical, genetic, and structural studies suggest that the physical interaction between TBX20 and CASZ1 is required for cardiac homeostasis, and further, that reduction or loss of this critical interaction leads to DCM. This work provides strong evidence that DCM can be inherited through a digenic mechanism.
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a gro tle nurd corepressor complex facilitates TBX20 dependent transcriptional repression
Journal of Proteome Research, 2013Co-Authors: Erin Kaltenbrun, Todd M. Greco, Christopher E. Slagle, Leslie M. Kennedy, Ileana M. Cristea, Frank L. ConlonAbstract:The cardiac transcription factor TBX20 has a critical role in the proper morphogenetic development of the vertebrate heart, and its misregulation has been implicated in human congenital heart disease. Although it is established that TBX20 exerts its function in the embryonic heart through positive and negative regulation of distinct gene programs, it is unclear how TBX20 mediates proper transcriptional regulation of its target genes. Here, using a combinatorial proteomic and bioinformatic approach, we present the first characterization of TBX20 transcriptional protein complexes. We have systematically investigated TBX20 protein-protein interactions by immunoaffinity purification of tagged TBX20 followed by proteomic analysis using GeLC-MS/MS, gene ontology classification, and functional network analysis. We demonstrate that TBX20 is associated with a chromatin remodeling network composed of TLE/Groucho co-repressors, members of the Nucleosome Remodeling and Deacetylase (NuRD) complex, the chromatin remodeling ATPases RUVBL1/RUVBL2, and the T-box repressor Tbx18. We determined that the interaction with TLE co-repressors is mediated via an eh1 binding motif in TBX20. Moreover, we demonstrated that ablation of this motif results in a failure to properly assemble the repression network and disrupts TBX20 function in vivo. Importantly, we validated TBX20-TLE interactions in the mouse embryonic heart, and identified developmental genes regulated by TBX20:TLE binding, thereby confirming a primary role for a TBX20-TLE repressor complex in embryonic heart development. Together, these studies suggest a model in which TBX20 associates with a Gro/TLE-NuRD repressor complex to prevent inappropriate gene activation within the forming heart.
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A Gro/TLE-NuRD corepressor complex facilitates TBX20-dependent transcriptional repression.
Journal of proteome research, 2013Co-Authors: Erin Kaltenbrun, Todd M. Greco, Christopher E. Slagle, Leslie M. Kennedy, Ileana M. Cristea, Frank L. ConlonAbstract:The cardiac transcription factor TBX20 has a critical role in the proper morphogenetic development of the vertebrate heart, and its misregulation has been implicated in human congenital heart disease. Although it is established that TBX20 exerts its function in the embryonic heart through positive and negative regulation of distinct gene programs, it is unclear how TBX20 mediates proper transcriptional regulation of its target genes. Here, using a combinatorial proteomic and bioinformatic approach, we present the first characterization of TBX20 transcriptional protein complexes. We have systematically investigated TBX20 protein-protein interactions by immunoaffinity purification of tagged TBX20 followed by proteomic analysis using GeLC-MS/MS, gene ontology classification, and functional network analysis. We demonstrate that TBX20 is associated with a chromatin remodeling network composed of TLE/Groucho co-repressors, members of the Nucleosome Remodeling and Deacetylase (NuRD) complex, the chromatin remodeling ATPases RUVBL1/RUVBL2, and the T-box repressor Tbx18. We determined that the interaction with TLE co-repressors is mediated via an eh1 binding motif in TBX20. Moreover, we demonstrated that ablation of this motif results in a failure to properly assemble the repression network and disrupts TBX20 function in vivo. Importantly, we validated TBX20-TLE interactions in the mouse embryonic heart, and identified developmental genes regulated by TBX20:TLE binding, thereby confirming a primary role for a TBX20-TLE repressor complex in embryonic heart development. Together, these studies suggest a model in which TBX20 associates with a Gro/TLE-NuRD repressor complex to prevent inappropriate gene activation within the forming heart.
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The BMP pathway acts to directly regulate TBX20 in the developing heart
Development (Cambridge England), 2010Co-Authors: Elizabeth M. Mandel, Erin Kaltenbrun, Thomas E. Callis, Xin-xin I. Zeng, Sara R. Marques, Deborah Yelon, Da-zhi Wang, Frank L. ConlonAbstract:TBX20 has been shown to be essential for vertebrate heart development. Mutations within the TBX20 coding region are associated with human congenital heart disease, and the loss of TBX20 in a wide variety of model systems leads to cardiac defects and eventually heart failure. Despite the crucial role of TBX20 in a range of cardiac cellular processes, the signal transduction pathways that act upstream of TBX20 remain unknown. Here, we have identified and characterized a conserved 334 bp TBX20 cardiac regulatory element that is directly activated by the BMP/SMAD1 signaling pathway. We demonstrate that this element is both necessary and sufficient to drive cardiac-specific expression of TBX20 in Xenopus, and that blocking SMAD1 signaling in vivo specifically abolishes transcription of TBX20, but not that of other cardiac factors, such as Tbx5 and MHC, in the developing heart. We further demonstrate that activation of TBX20 by SMAD1 is mediated by a set of novel, non-canonical, high-affinity SMAD-binding sites located within this regulatory element and that phospho-SMAD1 directly binds a non-canonical SMAD1 site in vivo. Finally, we show that these non-canonical sites are necessary and sufficient for TBX20 expression in Xenopus, and that reporter constructs containing these sites are expressed in a cardiac-specific manner in zebrafish and mouse. Collectively, our findings define TBX20 as a direct transcriptional target of the BMP/SMAD1 signaling pathway during cardiac maturation.
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Developmental expression patterns of Tbx1, Tbx2, Tbx5, and TBX20 in Xenopus tropicalis†
Developmental dynamics : an official publication of the American Association of Anatomists, 2006Co-Authors: Chris Showell, Elizabeth M. Mandel, Kathleen S. Christine, Frank L. ConlonAbstract:T-box genes have diverse functions during embryogenesis and are implicated in several human congenital disorders. Here, we report the identification, sequence analysis, and developmental expression patterns of four members of the T-box gene family in the diploid frog Xenopus tropicalis. These four genes—Tbx1, Tbx2, Tbx5, and TBX20— have been shown to influence cardiac development in a variety of organisms, in addition to their individual roles in regulating other aspects of embryonic development. Our results highlight the high degree of evolutionary conservation between orthologs of these genes in X. tropicalis and other vertebrates, both at the molecular level and in their developmental expression patterns, and also identify novel features of their expression. Thus, X. tropicalis represents a potentially valuable vertebrate model in which to further investigate the functions of these genes through genetic approaches. Developmental Dynamics 235:1623–1630, 2006. © 2006 Wiley-Liss, Inc.
Erin Kaltenbrun - One of the best experts on this subject based on the ideXlab platform.
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Formation of a TBX20-CASZ1 protein complex is protective against dilated cardiomyopathy and critical for cardiac homeostasis.
PLoS genetics, 2017Co-Authors: Leslie M. Kennedy, Erin Kaltenbrun, Todd M. Greco, Ileana M. Cristea, Brenda Temple, Laura E. Herring, Frank L. ConlonAbstract:By the age of 40, one in five adults without symptoms of cardiovascular disease are at risk for developing congestive heart failure. Within this population, dilated cardiomyopathy (DCM) remains one of the leading causes of disease and death, with nearly half of cases genetically determined. Though genetic and high throughput sequencing-based approaches have identified sporadic and inherited mutations in a multitude of genes implicated in cardiomyopathy, how combinations of asymptomatic mutations lead to cardiac failure remains a mystery. Since a number of studies have implicated mutations of the transcription factor TBX20 in congenital heart diseases, we investigated the underlying mechanisms, using an unbiased systems-based screen to identify novel, cardiac-specific binding partners. We demonstrated that TBX20 physically and genetically interacts with the essential transcription factor CASZ1. This interaction is required for survival, as mice heterozygous for both TBX20 and Casz1 die post-natally as a result of DCM. A TBX20 mutation associated with human familial DCM sterically interferes with the TBX20-CASZ1 interaction and provides a physical basis for how this human mutation disrupts normal cardiac function. Finally, we employed quantitative proteomic analyses to define the molecular pathways mis-regulated upon disruption of this novel complex. Collectively, our proteomic, biochemical, genetic, and structural studies suggest that the physical interaction between TBX20 and CASZ1 is required for cardiac homeostasis, and further, that reduction or loss of this critical interaction leads to DCM. This work provides strong evidence that DCM can be inherited through a digenic mechanism.
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a gro tle nurd corepressor complex facilitates TBX20 dependent transcriptional repression
Journal of Proteome Research, 2013Co-Authors: Erin Kaltenbrun, Todd M. Greco, Christopher E. Slagle, Leslie M. Kennedy, Ileana M. Cristea, Frank L. ConlonAbstract:The cardiac transcription factor TBX20 has a critical role in the proper morphogenetic development of the vertebrate heart, and its misregulation has been implicated in human congenital heart disease. Although it is established that TBX20 exerts its function in the embryonic heart through positive and negative regulation of distinct gene programs, it is unclear how TBX20 mediates proper transcriptional regulation of its target genes. Here, using a combinatorial proteomic and bioinformatic approach, we present the first characterization of TBX20 transcriptional protein complexes. We have systematically investigated TBX20 protein-protein interactions by immunoaffinity purification of tagged TBX20 followed by proteomic analysis using GeLC-MS/MS, gene ontology classification, and functional network analysis. We demonstrate that TBX20 is associated with a chromatin remodeling network composed of TLE/Groucho co-repressors, members of the Nucleosome Remodeling and Deacetylase (NuRD) complex, the chromatin remodeling ATPases RUVBL1/RUVBL2, and the T-box repressor Tbx18. We determined that the interaction with TLE co-repressors is mediated via an eh1 binding motif in TBX20. Moreover, we demonstrated that ablation of this motif results in a failure to properly assemble the repression network and disrupts TBX20 function in vivo. Importantly, we validated TBX20-TLE interactions in the mouse embryonic heart, and identified developmental genes regulated by TBX20:TLE binding, thereby confirming a primary role for a TBX20-TLE repressor complex in embryonic heart development. Together, these studies suggest a model in which TBX20 associates with a Gro/TLE-NuRD repressor complex to prevent inappropriate gene activation within the forming heart.
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A Gro/TLE-NuRD corepressor complex facilitates TBX20-dependent transcriptional repression.
Journal of proteome research, 2013Co-Authors: Erin Kaltenbrun, Todd M. Greco, Christopher E. Slagle, Leslie M. Kennedy, Ileana M. Cristea, Frank L. ConlonAbstract:The cardiac transcription factor TBX20 has a critical role in the proper morphogenetic development of the vertebrate heart, and its misregulation has been implicated in human congenital heart disease. Although it is established that TBX20 exerts its function in the embryonic heart through positive and negative regulation of distinct gene programs, it is unclear how TBX20 mediates proper transcriptional regulation of its target genes. Here, using a combinatorial proteomic and bioinformatic approach, we present the first characterization of TBX20 transcriptional protein complexes. We have systematically investigated TBX20 protein-protein interactions by immunoaffinity purification of tagged TBX20 followed by proteomic analysis using GeLC-MS/MS, gene ontology classification, and functional network analysis. We demonstrate that TBX20 is associated with a chromatin remodeling network composed of TLE/Groucho co-repressors, members of the Nucleosome Remodeling and Deacetylase (NuRD) complex, the chromatin remodeling ATPases RUVBL1/RUVBL2, and the T-box repressor Tbx18. We determined that the interaction with TLE co-repressors is mediated via an eh1 binding motif in TBX20. Moreover, we demonstrated that ablation of this motif results in a failure to properly assemble the repression network and disrupts TBX20 function in vivo. Importantly, we validated TBX20-TLE interactions in the mouse embryonic heart, and identified developmental genes regulated by TBX20:TLE binding, thereby confirming a primary role for a TBX20-TLE repressor complex in embryonic heart development. Together, these studies suggest a model in which TBX20 associates with a Gro/TLE-NuRD repressor complex to prevent inappropriate gene activation within the forming heart.
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The BMP pathway acts to directly regulate TBX20 in the developing heart
Development (Cambridge England), 2010Co-Authors: Elizabeth M. Mandel, Erin Kaltenbrun, Thomas E. Callis, Xin-xin I. Zeng, Sara R. Marques, Deborah Yelon, Da-zhi Wang, Frank L. ConlonAbstract:TBX20 has been shown to be essential for vertebrate heart development. Mutations within the TBX20 coding region are associated with human congenital heart disease, and the loss of TBX20 in a wide variety of model systems leads to cardiac defects and eventually heart failure. Despite the crucial role of TBX20 in a range of cardiac cellular processes, the signal transduction pathways that act upstream of TBX20 remain unknown. Here, we have identified and characterized a conserved 334 bp TBX20 cardiac regulatory element that is directly activated by the BMP/SMAD1 signaling pathway. We demonstrate that this element is both necessary and sufficient to drive cardiac-specific expression of TBX20 in Xenopus, and that blocking SMAD1 signaling in vivo specifically abolishes transcription of TBX20, but not that of other cardiac factors, such as Tbx5 and MHC, in the developing heart. We further demonstrate that activation of TBX20 by SMAD1 is mediated by a set of novel, non-canonical, high-affinity SMAD-binding sites located within this regulatory element and that phospho-SMAD1 directly binds a non-canonical SMAD1 site in vivo. Finally, we show that these non-canonical sites are necessary and sufficient for TBX20 expression in Xenopus, and that reporter constructs containing these sites are expressed in a cardiac-specific manner in zebrafish and mouse. Collectively, our findings define TBX20 as a direct transcriptional target of the BMP/SMAD1 signaling pathway during cardiac maturation.
Andreas Kispert - One of the best experts on this subject based on the ideXlab platform.
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Lack of Genetic Interaction between Tbx18 and Tbx2/TBX20 in Mouse Epicardial Development.
PloS one, 2016Co-Authors: Franziska Greulich, Henner F. Farin, Vincent M. Christoffels, Carsten Rudat, Andreas KispertAbstract:The epicardium, the outermost layer of the heart, is an essential source of cells and signals for the formation of the cardiac fibrous skeleton and the coronary vasculature, and for the maturation of the myocardium during embryonic development. The molecular factors that control epicardial mobilization and differentiation, and direct the epicardial-myocardial cross-talk are, however, insufficiently understood. The T-box transcription factor gene Tbx18 is specifically expressed in the epicardium of vertebrate embryos. Loss of Tbx18 is dispensable for epicardial development, but may influence coronary vessel maturation. In contrast, over-expression of an activator version of TBX18 severely impairs epicardial development by premature differentiation of epicardial cells into SMCs indicating a potential redundancy of Tbx18 with other repressors of the T-box gene family. Here, we show that Tbx2 and TBX20 are co-expressed with Tbx18 at different stages of epicardial development. Using a conditional gene targeting approach we find that neither the epicardial loss of Tbx2 nor the combined loss of Tbx2 and Tbx18 affects epicardial development. Similarly, we observed that the heterozygous loss of TBX20 with and without additional loss of Tbx18 does not impact on epicardial integrity and mobilization in mouse embryos. Thus, Tbx18 does not function redundantly with Tbx2 or TBX20 in epicardial development.
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lack of genetic interaction between tbx18 and tbx2 TBX20 in mouse epicardial development
PLOS ONE, 2016Co-Authors: Franziska Greulich, Henner F. Farin, Vincent M. Christoffels, Carsten Rudat, Andreas KispertAbstract:The epicardium, the outermost layer of the heart, is an essential source of cells and signals for the formation of the cardiac fibrous skeleton and the coronary vasculature, and for the maturation of the myocardium during embryonic development. The molecular factors that control epicardial mobilization and differentiation, and direct the epicardial-myocardial cross-talk are, however, insufficiently understood. The T-box transcription factor gene Tbx18 is specifically expressed in the epicardium of vertebrate embryos. Loss of Tbx18 is dispensable for epicardial development, but may influence coronary vessel maturation. In contrast, over-expression of an activator version of TBX18 severely impairs epicardial development by premature differentiation of epicardial cells into SMCs indicating a potential redundancy of Tbx18 with other repressors of the T-box gene family. Here, we show that Tbx2 and TBX20 are co-expressed with Tbx18 at different stages of epicardial development. Using a conditional gene targeting approach we find that neither the epicardial loss of Tbx2 nor the combined loss of Tbx2 and Tbx18 affects epicardial development. Similarly, we observed that the heterozygous loss of TBX20 with and without additional loss of Tbx18 does not impact on epicardial integrity and mobilization in mouse embryos. Thus, Tbx18 does not function redundantly with Tbx2 or TBX20 in epicardial development.
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TBX20, Smads, and the atrioventricular canal.
Trends in cardiovascular medicine, 2010Co-Authors: Reena Singh, Andreas KispertAbstract:Specification of chamber and nonchamber myocardium in the forming vertebrate heart is a crucial lineage decision on which most of the functional architecture of the mature organ is built. Members of the T-box ( Tbx ) gene family are decisive players in this early myocardial dichotomy by either promoting ( Tbx5 , TBX20 ) or inhibiting ( Tbx2, Tbx3 ) the chamber gene program in the early heart tube. Because Tbx5 and TBX20 are widely expressed in the linear heart tube, localized expression of Tbx2 and Tbx3 in regions fated to become primary myocardium of the atrioventricular canal and outflow tract is crucial to localize the chambers. Here, we will review recent findings that suggest an important role for TBX20 and Bmp2/Smad signaling in restricting Tbx2 activation to the atrioventricular canal and outflow tract. Surprisingly, TBX20 does not act as a direct transcriptional repressor of Tbx2 but sequesters receptor-activated Smad factors of the Bmp signaling pathway to prevent precocious Tbx2 transcription.
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TBX20 Interacts With Smads to Confine Tbx2 Expression to the Atrioventricular Canal
Circulation research, 2009Co-Authors: Reena Singh, Thomas Horsthuis, Henner F. Farin, Thomas Grieskamp, Julia Norden, Marianne Petry, Vincent Wakker, Antoon F.m. Moorman, Vincent M. Christoffels, Andreas KispertAbstract:Rationale: T-box transcription factors play critical roles in the coordinated formation of the working chambers and the atrioventricular canal (AVC). Tbx2 patterns embryonic myocardial cells to form the AVC and suppresses their differentiation into chamber myocardium. TBX20-deficient embryos, which fail to form chambers, ectopically express Tbx2 throughout the entire heart tube, providing a potential mechanism for the function of TBX20 in chamber differentiation. Objective: To identify the mechanism of Tbx2 suppression by TBX20 and to investigate the involvement of Tbx2 in TBX20-mediated chamber formation. Methods and Results: We generated TBX20 and Tbx2 single and double knockout embryos and observed that loss of Tbx2 did not rescue the TBX20-deficient heart from failure to form chambers. However, TBX20 is required to suppress Tbx2 in the developing chambers, a prerequisite to localize its strong differentiation-inhibiting activity to the AVC. We identified a bone morphogenetic protein (Bmp)/Smad-depende...
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TBX20 is essential for cardiac chamber differentiation and repression of Tbx2.
Development (Cambridge England), 2005Co-Authors: Manvendra K. Singh, Marianne Petry, Vincent M. Christoffels, José M. Dias, Mark-oliver Trowe, Karin Schuster-gossler, Antje Bürger, Johan Ericson, Andreas KispertAbstract:TBX20 , a member of the T-box family of transcriptional regulators, shows evolutionary conserved expression in the developing heart. In the mouse, TBX20 is expressed in the cardiac crescent, then in the endocardium and myocardium of the linear and looped heart tube before it is restricted to the atrioventricular canal and outflow tract in the multi-chambered heart. Here, we show that TBX20 is required for progression from the linear heart tube to a multi-chambered heart. Mice carrying a targeted mutation of TBX20 show early embryonic lethality due to hemodynamic failure. A linear heart tube with normal anteroposterior patterning is established in the mutant. The tube does not elongate, indicating a defect in recruitment of mesenchyme from the secondary heart field, even though markers of the secondary heart field are not affected. Furthermore, dorsoventral patterning of the tube, formation of working myocardium, looping, and further differentiation and morphogenesis fail. Instead, Tbx2 , Bmp2 and vinexin α ( Sh3d4 ), genes normally restricted to regions of primary myocardium and lining endocardium, are ectopically expressed in the linear heart tube of TBX20 mutant embryos. Because Tbx2 is both necessary and sufficient to repress chamber differentiation ([Christoffels et al., 2004a][1]; [Harrelson et al., 2004][2]), TBX20 may ensure progression to a multi-chambered heart by repressing Tbx2 in the myocardial precursor cells of the linear heart tube destined to form the chambers. [1]: #ref-16 [2]: #ref-29
Katherine E. Yutzey - One of the best experts on this subject based on the ideXlab platform.
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Overexpression of TBX20 in Adult Cardiomyocytes Promotes Proliferation and Improves Cardiac Function After Myocardial Infarction
Circulation, 2016Co-Authors: Fu-li Xiang, Minzhe Guo, Katherine E. YutzeyAbstract:Background —Adult mammalian cardiomyocytes (CM) have the potential to proliferate, but this is not sufficient to generate adequate CMs after myocardial infarction (MI). The transcription factor TBX20 is required for CM proliferation during development and adult CM homeostasis. The ability of TBX20 overexpression (TBX20 OE ) to promote adult CM proliferation and improve cardiac function after MI was examined. Methods and Results —TBX20 OE was induced specifically in adult mouse differentiated CMs. Increased CM proliferation and fetal-like characteristics were found in TBX20 OE hearts, compared to controls, without causing pathology 4 weeks after TBX20 OE at baseline. Moreover, TBX20 OE in adult CM after MI significantly improved survival, cardiac function, and infarct size 4 weeks post-MI. Improved cardiac repair, as indicated by increased CM proliferation and capillary density, was observed in the MI border zone of TBX20 OE hearts compared to controls. Expression of proliferation activator ( cyclin D1, E1 , and IGF1 ) and fetal contractile protein ( ssTNI, βMHC ) mRNA was increased, while negative cell-cycle regulators ( p21, Meis1 ) were decreased, in TBX20 OE hearts, compared to controls, under both baseline and MI conditions. TBX20 OE in adult hearts activates multiple pro-proliferation pathways including Akt, YAP and BMP. Interestingly, p21, Meis1 , and a novel cell-cycle inhibitory gene Btg2 , are directly bound and repressed by TBX20 with induction of proliferation in neonatal CM. Conclusions —TBX20 OE specifically in adult CM activates multiple cardiac proliferative pathways, directly represses cell-cycle inhibitory genes p21, Meis1 and Btg2 , promotes adult CM proliferation, and preserves cardiac performance post-MI.
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Abstract 23: Overexpression Of TBX20 In Adult Cardiomyocytes Promotes Cardiomyocyte Proliferation And Improves Cardiac Function Post Myocardial Infarction
Circulation Research, 2014Co-Authors: Fu-li Xiang, Katherine E. YutzeyAbstract:Background: Adult mammalian cardiomyocytes (CM) have the potential to proliferate, but this is not sufficient to compensate for the massive loss of functional CMs after myocardial infarction (MI), which remains a leading cause of death in the US. During embryonic heart development, the transcription factor TBX20 is required for CM proliferation, and TBX20 overexpression promotes fetal characteristics in adult CMs when initiated before birth in mice. We hypothesize that TBX20 overexpression (TBX20OE), when induced in adult CMs after injury, improves cardiac function and repair via dedifferentiation of CMs, thus promoting cell cycle re-entry and repair in mice post-MI. Methods and Results: αMHCMerCreMer (STG) and the inducible cardiomyocyte-specific TBX20 transgenic (αMHCMerCreMer/CAG-CAT-TBX20, DTG) mice were subjected to MI or sham surgeries. TBX20OE was induced 3 days post-surgery via tamoxifen to specifically target cardiac repair post-MI. In sham-operated mice, no difference in cardiac function or morphology was observed between DTG and STG groups. However, more proliferating CMs as labeled by Ki67 were found in DTG sham myocardium compared to STG. Expression of cyclin D1, E1 (cell cycle markers) and IGF1 mRNA was increased, while p21 (cell cycle inhibitor) and Meis1 (negative regulator of proliferation) were decreased, in DTG sham hearts compared to STG controls. In mice subjected to MI, cardiac function, as measured by echocardiography, was significantly improved, and the infarct scar size was smaller (58.1% vs 38.3%) in the DTG group compared to STG controls 2 and 4 weeks post-MI. Myocardial hypertrophy determined by heart to body weight ratio and myocyte diameter was also significantly reduced in DTG heart compared to STG 4 weeks post-MI. Thus, induction of TBX20OE post-MI injury leads to improved cardiac performance, decreased scar size, and decreased maladaptive cardiac remodeling. Ongoing studies will determine if proliferation indices (Ki67, pHH3, aurora kinase B) and cytokinesis of CM post-MI are increased in myocardium and isolated adult cardiomyocytes with TBX20OE. Conclusions: TBX20OE in adult CM activates cell proliferation markers and also improves cardiac function and repair in mice when induced post-MI.
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TBX20 promotes cardiomyocyte proliferation and persistence of fetal characteristics in adult mouse hearts
Journal of molecular and cellular cardiology, 2013Co-Authors: Santanu Chakraborty, Arunima Sengupta, Katherine E. YutzeyAbstract:While differentiated cardiomyocytes proliferate prior to birth, adult cardiomyocytes in mammals exhibit relatively little proliferative activity. The T-box transcription factor TBX20 is necessary and sufficient to promote prenatal cardiomyocyte proliferation, and TBX20 also is required for adult cardiac homeostasis. The ability of TBX20 to promote post-natal and adult cardiomyocyte proliferation was examined in mice with cardiomyocyte-specific TBX20 gain-of-function beginning in the fetal period. In adult hearts, increased TBX20 expression promotes cardiomyocyte proliferation and results in increased numbers of small, cycling, mononucleated cardiomyocytes, marked by persistent expression of fetal contractile protein genes. In adult cardiomyocytes in vivo and in neonatal rat cardiomyocytes in culture, TBX20 promotes the activation of BMP2/pSmad1/5/8 and PI3K/AKT/GSK3β/β-catenin signaling pathways concomitant with increased cell proliferation. Inhibition of PI3K/AKT/GSK3β/β-catenin signaling reduces, but does not eliminate, TBX20-mediated increases in cell proliferation, providing evidence for parallel regulatory pathways downstream of BMP/Smad1/5/8 signaling in promoting cardiomyocyte proliferation after birth. Thus, TBX20 overexpression beginning in the fetal period activates multiple cardiac proliferative pathways after birth and maintains adult cardiomyocytes in an immature state in vivo.
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TBX20 regulation of cardiac cell proliferation and lineage specialization during embryonic and fetal development in vivo.
Developmental biology, 2011Co-Authors: Santanu Chakraborty, Katherine E. YutzeyAbstract:TBX20 gain-of-function mutations in humans are associated with congenital heart malformations and myocardial defects. However the effects of increased TBX20 function during cardiac chamber development and maturation have not been reported previously. CAG-CAT-TBX20 transgenic mice were generated for Cre-dependent induction of TBX20 in myocardial lineages in the developing heart. βMHCCre-mediated overexpression of TBX20 in fetal ventricular cardiomyocytes results in increased thickness of compact myocardium, induction of cardiomyocyte proliferation, and increased expression of Bmp10 and pSmad1/5/8 at embryonic day (E) 14.5. βMHCCre-mediated TBX20 overexpression also leads to increased expression of cardiac conduction system (CCS) genes Tbx5, Cx40, and Cx43 throughout the ventricular myocardium. In contrast, Nkx2.5Cre mediated overexpression of TBX20 in the embryonic heart results in reduced cardiomyocyte proliferation, increased expression of a cell cycle inhibitor, p21CIP1, and decreased expression of Tbx2, Tbx5, and N-myc1 at E9.5, concomitant with decreased phospho-ERK1/2 expression. Together, these analyses demonstrate that TBX20 differentially regulates cell proliferation and cardiac lineage specification in embryonic versus fetal cardiomyocytes. Induction of pSmad1/5/8 at E14.5 and inhibition of dpERK expression at E9.5 are consistent with selective TBX20 regulation of these pathways in association with stage-specific effects on cardiomyocyte proliferation. Together, these in vivo data support distinct functions for TBX20 in regulation of cardiomyocyte lineage maturation and cell proliferation at embryonic and fetal stages of heart development.
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Twist1 function in endocardial cushion cell proliferation, migration, and differentiation during heart valve development
Developmental biology, 2008Co-Authors: Elaine L. Shelton, Katherine E. YutzeyAbstract:Twist1 is a bHLH transcription factor that regulates cell proliferation, migration, and differentiation in embryonic progenitor cell populations and transformed tumor cells. While much is known about Twist1's function in a variety of mesenchymal cell types, the role of Twist1 in endocardial cushion cells is unknown. Twist1 gain and loss of function experiments were performed in primary chicken endocardial cushion cells in order to elucidate its role in endocardial cushion development. These studies indicate that Twist1 can induce endocardial cushion cell proliferation as well as promote endocardial cushion cell migration. Furthermore, Twist1 is subject to BMP regulation and can induce expression of cell migration marker genes including Periostin, Cadherin 11, and Mmp2 while repressing markers of valve cell differentiation including Aggrecan. Previously, TBX20 has been implicated in endocardial cushion cell proliferation and differentiation, and in the current study, TBX20 also promotes cushion cell migration. Twist1 can induce TBX20 expression, while TBX20 does not affect Twist1 expression. Taken together, these data indicate a role for Twist1 upstream of TBX20 in promoting cell proliferation and migration and repressing differentiation in endocardial cushion cells during embryonic development.
Leslie M. Kennedy - One of the best experts on this subject based on the ideXlab platform.
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Formation of a TBX20-CASZ1 protein complex is protective against dilated cardiomyopathy and critical for cardiac homeostasis.
PLoS genetics, 2017Co-Authors: Leslie M. Kennedy, Erin Kaltenbrun, Todd M. Greco, Ileana M. Cristea, Brenda Temple, Laura E. Herring, Frank L. ConlonAbstract:By the age of 40, one in five adults without symptoms of cardiovascular disease are at risk for developing congestive heart failure. Within this population, dilated cardiomyopathy (DCM) remains one of the leading causes of disease and death, with nearly half of cases genetically determined. Though genetic and high throughput sequencing-based approaches have identified sporadic and inherited mutations in a multitude of genes implicated in cardiomyopathy, how combinations of asymptomatic mutations lead to cardiac failure remains a mystery. Since a number of studies have implicated mutations of the transcription factor TBX20 in congenital heart diseases, we investigated the underlying mechanisms, using an unbiased systems-based screen to identify novel, cardiac-specific binding partners. We demonstrated that TBX20 physically and genetically interacts with the essential transcription factor CASZ1. This interaction is required for survival, as mice heterozygous for both TBX20 and Casz1 die post-natally as a result of DCM. A TBX20 mutation associated with human familial DCM sterically interferes with the TBX20-CASZ1 interaction and provides a physical basis for how this human mutation disrupts normal cardiac function. Finally, we employed quantitative proteomic analyses to define the molecular pathways mis-regulated upon disruption of this novel complex. Collectively, our proteomic, biochemical, genetic, and structural studies suggest that the physical interaction between TBX20 and CASZ1 is required for cardiac homeostasis, and further, that reduction or loss of this critical interaction leads to DCM. This work provides strong evidence that DCM can be inherited through a digenic mechanism.
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a gro tle nurd corepressor complex facilitates TBX20 dependent transcriptional repression
Journal of Proteome Research, 2013Co-Authors: Erin Kaltenbrun, Todd M. Greco, Christopher E. Slagle, Leslie M. Kennedy, Ileana M. Cristea, Frank L. ConlonAbstract:The cardiac transcription factor TBX20 has a critical role in the proper morphogenetic development of the vertebrate heart, and its misregulation has been implicated in human congenital heart disease. Although it is established that TBX20 exerts its function in the embryonic heart through positive and negative regulation of distinct gene programs, it is unclear how TBX20 mediates proper transcriptional regulation of its target genes. Here, using a combinatorial proteomic and bioinformatic approach, we present the first characterization of TBX20 transcriptional protein complexes. We have systematically investigated TBX20 protein-protein interactions by immunoaffinity purification of tagged TBX20 followed by proteomic analysis using GeLC-MS/MS, gene ontology classification, and functional network analysis. We demonstrate that TBX20 is associated with a chromatin remodeling network composed of TLE/Groucho co-repressors, members of the Nucleosome Remodeling and Deacetylase (NuRD) complex, the chromatin remodeling ATPases RUVBL1/RUVBL2, and the T-box repressor Tbx18. We determined that the interaction with TLE co-repressors is mediated via an eh1 binding motif in TBX20. Moreover, we demonstrated that ablation of this motif results in a failure to properly assemble the repression network and disrupts TBX20 function in vivo. Importantly, we validated TBX20-TLE interactions in the mouse embryonic heart, and identified developmental genes regulated by TBX20:TLE binding, thereby confirming a primary role for a TBX20-TLE repressor complex in embryonic heart development. Together, these studies suggest a model in which TBX20 associates with a Gro/TLE-NuRD repressor complex to prevent inappropriate gene activation within the forming heart.
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A Gro/TLE-NuRD corepressor complex facilitates TBX20-dependent transcriptional repression.
Journal of proteome research, 2013Co-Authors: Erin Kaltenbrun, Todd M. Greco, Christopher E. Slagle, Leslie M. Kennedy, Ileana M. Cristea, Frank L. ConlonAbstract:The cardiac transcription factor TBX20 has a critical role in the proper morphogenetic development of the vertebrate heart, and its misregulation has been implicated in human congenital heart disease. Although it is established that TBX20 exerts its function in the embryonic heart through positive and negative regulation of distinct gene programs, it is unclear how TBX20 mediates proper transcriptional regulation of its target genes. Here, using a combinatorial proteomic and bioinformatic approach, we present the first characterization of TBX20 transcriptional protein complexes. We have systematically investigated TBX20 protein-protein interactions by immunoaffinity purification of tagged TBX20 followed by proteomic analysis using GeLC-MS/MS, gene ontology classification, and functional network analysis. We demonstrate that TBX20 is associated with a chromatin remodeling network composed of TLE/Groucho co-repressors, members of the Nucleosome Remodeling and Deacetylase (NuRD) complex, the chromatin remodeling ATPases RUVBL1/RUVBL2, and the T-box repressor Tbx18. We determined that the interaction with TLE co-repressors is mediated via an eh1 binding motif in TBX20. Moreover, we demonstrated that ablation of this motif results in a failure to properly assemble the repression network and disrupts TBX20 function in vivo. Importantly, we validated TBX20-TLE interactions in the mouse embryonic heart, and identified developmental genes regulated by TBX20:TLE binding, thereby confirming a primary role for a TBX20-TLE repressor complex in embryonic heart development. Together, these studies suggest a model in which TBX20 associates with a Gro/TLE-NuRD repressor complex to prevent inappropriate gene activation within the forming heart.
