1
|
Boogerd CJ, Aneas I, Sakabe N, Dirschinger RJ, Cheng QJ, Zhou B, Chen J, Nobrega MA, Evans SM. Probing chromatin landscape reveals roles of endocardial TBX20 in septation. J Clin Invest 2016; 126:3023-35. [PMID: 27348591 DOI: 10.1172/jci85350] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 05/05/2016] [Indexed: 12/29/2022] Open
Abstract
Mutations in the T-box transcription factor TBX20 are associated with multiple forms of congenital heart defects, including cardiac septal abnormalities, but our understanding of the contributions of endocardial TBX20 to heart development remains incomplete. Here, we investigated how TBX20 interacts with endocardial gene networks to drive the mesenchymal and myocardial movements that are essential for outflow tract and atrioventricular septation. Selective ablation of Tbx20 in murine endocardial lineages reduced the expression of extracellular matrix and cell migration genes that are critical for septation. Using the assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq), we identified accessible chromatin within endocardial lineages and intersected these data with TBX20 ChIP-seq and chromatin loop maps to determine that TBX20 binds a conserved long-range enhancer to regulate versican (Vcan) expression. We also observed reduced Vcan expression in Tbx20-deficient mice, supporting a direct role for TBX20 in Vcan regulation. Further, we show that the Vcan enhancer drove reporter gene expression in endocardial lineages in a TBX20-binding site-dependent manner. This work illuminates gene networks that interact with TBX20 to orchestrate cardiac septation and provides insight into the chromatin landscape of endocardial lineages during septation.
Collapse
|
2
|
Atkinson AJ, Logantha SJRJ, Hao G, Yanni J, Fedorenko O, Sinha A, Gilbert SH, Benson AP, Buckley DL, Anderson RH, Boyett MR, Dobrzynski H. Functional, anatomical, and molecular investigation of the cardiac conduction system and arrhythmogenic atrioventricular ring tissue in the rat heart. J Am Heart Assoc 2013; 2:e000246. [PMID: 24356527 PMCID: PMC3886739 DOI: 10.1161/jaha.113.000246] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background The cardiac conduction system consists of the sinus node, nodal extensions, atrioventricular (AV) node, penetrating bundle, bundle branches, and Purkinje fibers. Node‐like AV ring tissue also exists at the AV junctions, and the right and left rings unite at the retroaortic node. The study aims were to (1) construct a 3‐dimensional anatomical model of the AV rings and retroaortic node, (2) map electrical activation in the right ring and study its action potential characteristics, and (3) examine gene expression in the right ring and retroaortic node. Methods and Results Three‐dimensional reconstruction (based on magnetic resonance imaging, histology, and immunohistochemistry) showed the extent and organization of the specialized tissues (eg, how the AV rings form the right and left nodal extensions into the AV node). Multiextracellular electrode array and microelectrode mapping of isolated right ring preparations revealed robust spontaneous activity with characteristic diastolic depolarization. Using laser microdissection gene expression measured at the mRNA level (using quantitative PCR) and protein level (using immunohistochemistry and Western blotting) showed that the right ring and retroaortic node, like the sinus node and AV node but, unlike ventricular muscle, had statistically significant higher expression of key transcription factors (including Tbx3, Msx2, and Id2) and ion channels (including HCN4, Cav3.1, Cav3.2, Kv1.5, SK1, Kir3.1, and Kir3.4) and lower expression of other key ion channels (Nav1.5 and Kir2.1). Conclusions The AV rings and retroaortic node possess gene expression profiles similar to that of the AV node. Ion channel expression and electrophysiological recordings show the AV rings could act as ectopic pacemakers and a source of atrial tachycardia.
Collapse
Affiliation(s)
- Andrew J. Atkinson
- University of Manchester, UK (A.J.A., S.J.J.L., G.H., J.Y., O.F., A.S., R.H.A., M.R.B., H.D.)
| | | | - Guoliang Hao
- University of Manchester, UK (A.J.A., S.J.J.L., G.H., J.Y., O.F., A.S., R.H.A., M.R.B., H.D.)
| | - Joseph Yanni
- University of Manchester, UK (A.J.A., S.J.J.L., G.H., J.Y., O.F., A.S., R.H.A., M.R.B., H.D.)
| | - Olga Fedorenko
- University of Manchester, UK (A.J.A., S.J.J.L., G.H., J.Y., O.F., A.S., R.H.A., M.R.B., H.D.)
- National Research Tomsk Polytechnic University and Mental Health Research Institute SB RAMSci, Tomsk, Russia (O.F.)
| | - Aditi Sinha
- University of Manchester, UK (A.J.A., S.J.J.L., G.H., J.Y., O.F., A.S., R.H.A., M.R.B., H.D.)
| | | | | | | | - Robert H. Anderson
- University of Manchester, UK (A.J.A., S.J.J.L., G.H., J.Y., O.F., A.S., R.H.A., M.R.B., H.D.)
| | - Mark R. Boyett
- University of Manchester, UK (A.J.A., S.J.J.L., G.H., J.Y., O.F., A.S., R.H.A., M.R.B., H.D.)
| | - Halina Dobrzynski
- University of Manchester, UK (A.J.A., S.J.J.L., G.H., J.Y., O.F., A.S., R.H.A., M.R.B., H.D.)
| |
Collapse
|
3
|
Wystub K, Besser J, Bachmann A, Boettger T, Braun T. miR-1/133a clusters cooperatively specify the cardiomyogenic lineage by adjustment of myocardin levels during embryonic heart development. PLoS Genet 2013; 9:e1003793. [PMID: 24068960 PMCID: PMC3777988 DOI: 10.1371/journal.pgen.1003793] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 07/29/2013] [Indexed: 11/19/2022] Open
Abstract
miRNAs are small RNAs directing many developmental processes by posttranscriptional regulation of protein-coding genes. We uncovered a new role for miR-1-1/133a-2 and miR-1-2/133a-1 clusters in the specification of embryonic cardiomyocytes allowing transition from an immature state characterized by expression of smooth muscle (SM) genes to a more mature fetal phenotype. Concomitant knockout of miR-1-1/133a-2 and miR-1-2/133a-1 released suppression of the transcriptional co-activator myocardin, a major regulator of SM gene expression, but not of its binding partner SRF. Overexpression of myocardin in the embryonic heart essentially recapitulated the miR-1/133a mutant phenotype at the molecular level, arresting embryonic cardiomyocytes in an immature state. Interestingly, the majority of postulated miR-1/133a targets was not altered in double mutant mice, indicating that the ability of miR-1/133a to suppress target molecules strongly depends on the cellular context. Finally, we show that myocardin positively regulates expression of miR-1/133a, thus constituting a negative feedback loop that is essential for early cardiac development.
Collapse
Affiliation(s)
- Katharina Wystub
- Max-Planck-Institut für Herz- und Lungenforschung, Department of Cardiac Development and Remodelling, Bad Nauheim, Germany
| | - Johannes Besser
- Max-Planck-Institut für Herz- und Lungenforschung, Department of Cardiac Development and Remodelling, Bad Nauheim, Germany
| | - Angela Bachmann
- Max-Planck-Institut für Herz- und Lungenforschung, Department of Cardiac Development and Remodelling, Bad Nauheim, Germany
| | - Thomas Boettger
- Max-Planck-Institut für Herz- und Lungenforschung, Department of Cardiac Development and Remodelling, Bad Nauheim, Germany
| | - Thomas Braun
- Max-Planck-Institut für Herz- und Lungenforschung, Department of Cardiac Development and Remodelling, Bad Nauheim, Germany
| |
Collapse
|