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Sun Y, Wang L, Zhu T, Wu B, Wang G, Luo Z, Li C, Wei W, Liu Z. Single-cell transcriptomic landscapes of the otic neuronal lineage at multiple early embryonic ages. Cell Rep 2022; 38:110542. [PMID: 35320729 DOI: 10.1016/j.celrep.2022.110542] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 12/03/2021] [Accepted: 02/25/2022] [Indexed: 11/20/2022] Open
Abstract
Inner ear vestibular and spiral ganglion neurons (VGNs and SGNs) are known to play pivotal roles in balance control and sound detection. However, the molecular mechanisms underlying otic neurogenesis at early embryonic ages have remained unclear. Here, we use single-cell RNA sequencing to reveal the transcriptomes of mouse otic tissues at three embryonic ages, embryonic day 9.5 (E9.5), E11.5, and E13.5, covering proliferating and undifferentiated otic neuroblasts and differentiating VGNs and SGNs. We validate the high quality of our studies by using multiple assays, including genetic fate mapping analysis, and we uncover several genes upregulated in neuroblasts or differentiating VGNs and SGNs, such as Shox2, Myt1, Casz1, and Sall3. Notably, our findings suggest a general cascaded differentiation trajectory during early otic neurogenesis. The comprehensive understanding of early otic neurogenesis provided by our study holds critical implications for both basic and translational research.
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2
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Yang T, Huang Z, Li H, Wang L, Chen Y. Conjugated activation of myocardial-specific transcription of Gja5 by a pair of Nkx2-5- Shox2 co-responsive elements. Dev Biol 2020; 465:79-87. [PMID: 32687896 DOI: 10.1016/j.ydbio.2020.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 02/08/2023]
Abstract
The sinoatrial node (SAN) is the primary pacemaker in the heart. During cardiogenesis, Shox2 and Nkx2-5 are co-expressed in the junction domain of the SAN and regulate pacemaker cell fate through a Shox2-Nkx2-5 antagonism. Cx40 is a marker of working myocardium and an Nkx2-5 transcriptional output antagonized by Shox2, but the underlying regulatory mechanisms remain elusive. Here we characterized a bona fide myocardial-specific Gja5 (coding gene of Cx40) distal enhancer consisting of a pair of Nkx2-5 and Shox2 co-bound elements in the regulatory region of Gja5. Transgenic reporter assays revealed that neither element alone, but the conjugation of both elements together, drives myocardial-specific transcription. Genetic analyses confirmed that the activation of this enhancer depends on Nkx2-5 but is inhibited by Shox2 in vivo, and its presence is essential for Gja5 expression in the myocardium but not the endothelial cells of the heart. Furthermore, chromatin conformation analysis showed an Nkx2-5-dependent loop formation between these two elements and the Gja5 promoter in vivo, indicating that Nkx2-5 bridges the conjugated activation of this enhancer by pairing the two elements to the Gja5 promoter.
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3
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Iwata R, Makanae A, Satoh A. Stability and plasticity of positional memory during limb regeneration in Ambystoma mexicanum. Dev Dyn 2019; 249:342-353. [PMID: 31386776 DOI: 10.1002/dvdy.96] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/26/2019] [Accepted: 07/30/2019] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Urodele amphibians are capable of regenerating their organs after severe damage. During such regeneration, participating cells are given differentiation instructions by the surrounding cells. Limb regeneration has been investigated as a representative phenomenon of organ regeneration. Cells known as blastema cells are induced after limb amputation. In this process, dermal fibroblasts are dedifferentiated and become undifferentiated similar to limb bud cells. Just like limb bud cells, the induced blastema cells are positioned along the three limb developmental axes: the dorsoventral, the anteroposterior, and the proximodistal. The accurate developmental axes are essential for reforming the structures correctly. Despite the importance of the developmental axes, the relationship between the newly establishing developmental axes and existing limb axes was not well described with molecular markers. RESULTS In this study, we grafted skin from GFP-transgenic axolotls and traced the cell lineage with position-specific gene expressions in order to investigate the correlation of the newly established axes and cellular origin. Shh- and Lmx1b-expressing cells emerged from the posterior skin and dorsal skin, respectively, even though the skin was transplanted to an inconsistent position. Shox2, a posterior marker gene, could be activated in cells derived from distal skin. CONCLUSIONS Our results suggest that the location memories on anteroposterior and dorsoventral axes are relatively stable in a regenerating blastema though cellular differentiation is reprogrammed.
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Affiliation(s)
- Reiko Iwata
- Okayama University, Research Core for Interdisciplinary Sciences (RCIS), Okayama, Japan
| | - Aki Makanae
- Okayama University, Research Core for Interdisciplinary Sciences (RCIS), Okayama, Japan
| | - Akira Satoh
- Okayama University, Research Core for Interdisciplinary Sciences (RCIS), Okayama, Japan
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4
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Li H, Li D, Wang Y, Huang Z, Xu J, Yang T, Wang L, Tang Q, Cai CL, Huang H, Zhang Y, Chen Y. Nkx2-5 defines a subpopulation of pacemaker cells and is essential for the physiological function of the sinoatrial node in mice. Development 2019; 146:dev.178145. [PMID: 31320323 DOI: 10.1242/dev.178145] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 07/04/2019] [Indexed: 02/05/2023]
Abstract
The sinoatrial node (SAN), the primary cardiac pacemaker, consists of a head domain and a junction/tail domain that exhibit different functional properties. However, the underlying molecular mechanism defining these two pacemaker domains remains elusive. Nkx2-5 is a key transcription factor essential for the formation of the working myocardium, but it was generally thought to be detrimental to SAN development. However, Nkx2-5 is expressed in the developing SAN junction, suggesting a role for Nkx2-5 in SAN junction development and function. In this study, we present unambiguous evidence that SAN junction cells exhibit unique action potential configurations intermediate to those manifested by the SAN head and the surrounding atrial cells, suggesting a specific role for the junction cells in impulse generation and in SAN-atrial exit conduction. Single-cell RNA-seq analyses support this concept. Although Nkx2-5 inactivation in the SAN junction did not cause a malformed SAN at birth, the mutant mice manifested sinus node dysfunction. Thus, Nkx2-5 defines a population of pacemaker cells in the transitional zone. Despite Nkx2-5 being dispensable for SAN morphogenesis during embryogenesis, its deletion hampers atrial activation by the pacemaker.
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Affiliation(s)
- Hua Li
- Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian Province 350108, PR China.,Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Dainan Li
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Yuzhi Wang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Zhen Huang
- Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian Province 350108, PR China
| | - Jue Xu
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA.,West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan Province 610041, PR China
| | - Tianfang Yang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Linyan Wang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA.,State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province 610041, PR China
| | - Qinghuang Tang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Chen-Leng Cai
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Hai Huang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Yanding Zhang
- Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian Province 350108, PR China
| | - YiPing Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
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5
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Hoffmann S, Paone C, Sumer SA, Diebold S, Weiss B, Roeth R, Clauss S, Klier I, Kääb S, Schulz A, Wild PS, Ghrib A, Zeller T, Schnabel RB, Just S, Rappold GA. Functional Characterization of Rare Variants in the SHOX2 Gene Identified in Sinus Node Dysfunction and Atrial Fibrillation. Front Genet 2019; 10:648. [PMID: 31354791 PMCID: PMC6637028 DOI: 10.3389/fgene.2019.00648] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/19/2019] [Indexed: 12/21/2022] Open
Abstract
Sinus node dysfunction (SND) and atrial fibrillation (AF) often coexist; however, the molecular mechanisms linking both conditions remain elusive. Mutations in the homeobox-containing SHOX2 gene have been recently associated with early-onset and familial AF. Shox2 is a key regulator of sinus node development, and its deficiency leads to bradycardia, as demonstrated in animal models. To provide an extended SHOX2 gene analysis in patients with distinct arrhythmias, we investigated SHOX2 as a susceptibility gene for SND and AF by screening 98 SND patients and 450 individuals with AF. The functional relevance of the novel mutations was investigated in vivo and in vitro, together with the previously reported p.H283Q variant. A heterozygous missense mutation (p.P33R) was identified in the SND cohort and four heterozygous variants (p.G77D, p.L129=, p.L130F, p.A293=) in the AF cohort. Overexpression of the pathogenic predicted mutations in zebrafish revealed pericardial edema for p.G77D and the positive control p.H283Q, whereas the p.P33R and p.A293= variants showed no effect. In addition, a dominant-negative effect with reduced heart rates was detected for p.G77D and p.H283Q. In vitro reporter assays demonstrated for both missense variants p.P33R and p.G77D significantly impaired transactivation activity, similar to the described p.H283Q variant. Also, a reduced Bmp4 target gene expression was revealed in zebrafish hearts upon overexpression of the p.P33R mutant. This study associates additional rare variants in the SHOX2 gene implicated in the susceptibility to distinct arrhythmias and allows frequency estimations in the AF cohort (3/990). We also demonstrate for the first time a genetic link between SND and AF involving SHOX2. Moreover, our data highlight the importance of functional investigations of rare variants.
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Affiliation(s)
- Sandra Hoffmann
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Christoph Paone
- Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Simon A Sumer
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Sabrina Diebold
- Department of Internal Medicine II, University of Ulm, Ulm, Germany
| | - Birgit Weiss
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany
| | - Ralph Roeth
- Department of Human Molecular Genetics, Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany
| | - Sebastian Clauss
- Department of Medicine I, Klinikum Grosshadern, University of Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Ina Klier
- Department of Medicine I, Klinikum Grosshadern, University of Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Stefan Kääb
- Department of Medicine I, Klinikum Grosshadern, University of Munich (LMU), Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Munich, Munich, Germany
| | - Andreas Schulz
- Preventive Cardiology and Preventive Medicine, Center for Cardiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Philipp S Wild
- Preventive Cardiology and Preventive Medicine, Center for Cardiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Adil Ghrib
- Department of General and Interventional Cardiology, University Heart Center Hamburg (UHZ), University Hospital Hamburg/Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Hamburg/Kiel/Luebeck, Hamburg, Germany
| | - Tanja Zeller
- Department of General and Interventional Cardiology, University Heart Center Hamburg (UHZ), University Hospital Hamburg/Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Hamburg/Kiel/Luebeck, Hamburg, Germany
| | - Renate B Schnabel
- Department of General and Interventional Cardiology, University Heart Center Hamburg (UHZ), University Hospital Hamburg/Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Hamburg/Kiel/Luebeck, Hamburg, 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 of Heidelberg, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, Heidelberg, Germany
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6
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Abstract
The formation and conduction of electrocardiosignals and the synchronous contraction of atria and ventricles with rhythmicity are both triggered and regulated by the cardiac conduction system (CCS). Defect of this system will lead to various types of cardiac arrhythmias. In recent years, the research progress of molecular genetics and developmental biology revealed a clearer understanding of differentiation and development of the cardiac conduction system and their regulatory mechanisms. Short stature homeobox 2 (Shox2) transcription factor, encoded by Shox2 gene in the mouse, is crucial in the formation and differentiation of the sinoatrial node (SAN). Shox2 drives embryonic development processes and is widely expressed in the appendicular skeleton, palate, temporomandibular joints, and heart. Mutations of Shox2 can lead to dysembryoplasia and abnormal phenotypes, including bradycardiac arrhythmia. In this review, we provide a summary of the latest research progress on the regulatory effects of the Shox2 gene in differentiation and development processes of the cardiac conduction system, hoping to deepen the knowledge and understanding of this systematic process based on the cardiac conduction system. Overall, the Shox2 gene is intimately involved in the differentiation and development of cardiac conduction system, especially sinoatrial node. We also summarize the current information about human SHOX2. This review article provides a new direction in biological pacemaker therapies.
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Affiliation(s)
- Wenyu Hu
- Department of Cardiology, The First Affiliated Hospital of China Medical University
| | - Yanguo Xin
- Department of Cardiology, West China Hospital of Sichuan University
| | - Yinan Zhao
- Department of Neurology, The First Affiliated Hospital of China Medical University
| | - Jian Hu
- Department of Cardiology, The First Affiliated Hospital of China Medical University
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7
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Hoffmann S, Schmitteckert S, Griesbeck A, Preiss H, Sumer S, Rolletschek A, Granzow M, Eckstein V, Niesler B, Rappold GA. Comparative expression analysis of Shox2-deficient embryonic stem cell-derived sinoatrial node-like cells. Stem Cell Res 2017; 21:51-57. [PMID: 28390247 DOI: 10.1016/j.scr.2017.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [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: 02/06/2017] [Revised: 03/21/2017] [Accepted: 03/24/2017] [Indexed: 02/05/2023] Open
Abstract
The homeodomain transcription factor Shox2 controls the development and function of the native cardiac pacemaker, the sinoatrial node (SAN). Moreover, SHOX2 mutations have been associated with cardiac arrhythmias in humans. For detailed examination of Shox2-dependent developmental mechanisms in SAN cells, we established a murine embryonic stem cell (ESC)-based model using Shox2 as a molecular tool. Shox2+/+ and Shox2-/- ESC clones were isolated and differentiated according to five different protocols in order to evaluate the most efficient enrichment of SAN-like cells. Expression analysis of cell subtype-specific marker genes revealed most efficient enrichment after CD166-based cell sorting. Comparative cardiac expression profiles of Shox2+/+ and Shox2-/- ESCs were examined by nCounter technology. Among other genes, we identified Nppb as a novel putative Shox2 target during differentiation in ESCs. Differential expression of Nppb could be confirmed in heart tissue of Shox2-/- embryos. Taken together, we established an ESC-based cardiac differentiation model and successfully purified Shox2+/+ and Shox2-/- SAN-like cells. This now provides an excellent basis for the investigation of molecular mechanisms under physiological and pathophysiological conditions for evaluating novel therapeutic approaches.
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Affiliation(s)
- Sandra Hoffmann
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, Germany; DZHK, German Centre for Cardiovascular Research, Partner site Heidelberg/Mannheim, Germany
| | - Stefanie Schmitteckert
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, Germany
| | - Anne Griesbeck
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, Germany
| | - Hannes Preiss
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, Germany
| | - Simon Sumer
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, Germany; DZHK, German Centre for Cardiovascular Research, Partner site Heidelberg/Mannheim, Germany
| | - Alexandra Rolletschek
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | - Martin Granzow
- Department of Human Genetics, Institute of Human Genetics, University Heidelberg, Germany
| | - Volker Eckstein
- FACS Core Facility, Department of Medicine V, University Hospital Heidelberg, Germany
| | - Beate Niesler
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, Germany; DZHK, German Centre for Cardiovascular Research, Partner site Heidelberg/Mannheim, Germany; nCounter Core Facility, Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, Germany
| | - Gudrun A Rappold
- Department of Human Molecular Genetics, Institute of Human Genetics, University Heidelberg, Germany; DZHK, German Centre for Cardiovascular Research, Partner site Heidelberg/Mannheim, Germany.
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8
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Ye W, Song Y, Huang Z, Osterwalder M, Ljubojevic A, Xu J, Bobick B, Abassah-Oppong S, Ruan N, Shamby R, Yu D, Zhang L, Cai CL, Visel A, Zhang Y, Cobb J, Chen Y. A unique stylopod patterning mechanism by Shox2-controlled osteogenesis. Development 2016; 143:2548-60. [PMID: 27287812 PMCID: PMC4958343 DOI: 10.1242/dev.138750] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 05/31/2016] [Indexed: 02/05/2023]
Abstract
Vertebrate appendage patterning is programmed by Hox-TALE factor-bound regulatory elements. However, it remains unclear which cell lineages are commissioned by Hox-TALE factors to generate regional specific patterns and whether other Hox-TALE co-factors exist. In this study, we investigated the transcriptional mechanisms controlled by the Shox2 transcriptional regulator in limb patterning. Harnessing an osteogenic lineage-specific Shox2 inactivation approach we show that despite widespread Shox2 expression in multiple cell lineages, lack of the stylopod observed upon Shox2 deficiency is a specific result of Shox2 loss of function in the osteogenic lineage. ChIP-Seq revealed robust interaction of Shox2 with cis-regulatory enhancers clustering around skeletogenic genes that are also bound by Hox-TALE factors, supporting a lineage autonomous function of Shox2 in osteogenic lineage fate determination and skeleton patterning. Pbx ChIP-Seq further allowed the genome-wide identification of cis-regulatory modules exhibiting co-occupancy of Pbx, Meis and Shox2 transcriptional regulators. Integrative analysis of ChIP-Seq and RNA-Seq data and transgenic enhancer assays indicate that Shox2 patterns the stylopod as a repressor via interaction with enhancers active in the proximal limb mesenchyme and antagonizes the repressive function of TALE factors in osteogenesis.
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Affiliation(s)
- Wenduo Ye
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Yingnan Song
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian 350108, People's Republic of China
| | - Zhen Huang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian 350108, People's Republic of China
| | | | - Anja Ljubojevic
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Jue Xu
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan 610041, People's Republic of China
| | - Brent Bobick
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Samuel Abassah-Oppong
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Ningsheng Ruan
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian 350108, People's Republic of China
| | - Ross Shamby
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Diankun Yu
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Lu Zhang
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Chen-Leng Cai
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Axel Visel
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA School of Natural Sciences, University of California at Merced, Merced, CA 95343, USA
| | - Yanding Zhang
- Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian 350108, People's Republic of China
| | - John Cobb
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - YiPing Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian 350108, People's Republic of China
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9
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Ye W, Wang J, Song Y, Yu D, Sun C, Liu C, Chen F, Zhang Y, Wang F, Harvey RP, Schrader L, Martin JF, Chen Y. A common Shox2-Nkx2-5 antagonistic mechanism primes the pacemaker cell fate in the pulmonary vein myocardium and sinoatrial node. Development 2015; 142:2521-32. [PMID: 26138475 DOI: 10.1242/dev.120220] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 06/04/2015] [Indexed: 12/26/2022]
Abstract
In humans, atrial fibrillation is often triggered by ectopic pacemaking activity in the myocardium sleeves of the pulmonary vein (PV) and systemic venous return. The genetic programs that abnormally reinforce pacemaker properties at these sites and how this relates to normal sinoatrial node (SAN) development remain uncharacterized. It was noted previously that Nkx2-5, which is expressed in the PV myocardium and reinforces a chamber-like myocardial identity in the PV, is lacking in the SAN. Here we present evidence that in mice Shox2 antagonizes the transcriptional output of Nkx2-5 in the PV myocardium and in a functional Nkx2-5(+) domain within the SAN to determine cell fate. Shox2 deletion in the Nkx2-5(+) domain of the SAN caused sick sinus syndrome, associated with the loss of the pacemaker program. Explanted Shox2(+) cells from the embryonic PV myocardium exhibited pacemaker characteristics including node-like electrophysiological properties and the capability to pace surrounding Shox2(-) cells. Shox2 deletion led to Hcn4 ablation in the developing PV myocardium. Nkx2-5 hypomorphism rescued the requirement for Shox2 for the expression of genes essential for SAN development in Shox2 mutants. Similarly, the pacemaker-like phenotype induced in the PV myocardium in Nkx2-5 hypomorphs reverted back to a working myocardial phenotype when Shox2 was simultaneously deleted. A similar mechanism is also adopted in differentiated embryoid bodies. We found that Shox2 interacts with Nkx2-5 directly, and discovered a substantial genome-wide co-occupancy of Shox2, Nkx2-5 and Tbx5, further supporting a pivotal role for Shox2 in the core myogenic program orchestrating venous pole and pacemaker development.
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Affiliation(s)
- Wenduo Ye
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Jun Wang
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine and the Texas Heart Institute, Houston, TX 77030, USA
| | - Yingnan Song
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Science, Fujian Normal University, Fuzhou, Fujian 350108, P.R. China
| | - Diankun Yu
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Cheng Sun
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Chao Liu
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Fading Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - Yanding Zhang
- Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Science, Fujian Normal University, Fuzhou, Fujian 350108, P.R. China
| | - Fen Wang
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
| | - Richard P Harvey
- Developmental and Stem Cell Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia St. Vincent's Clinical School and School of Biological and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - Laura Schrader
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
| | - James F Martin
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine and the Texas Heart Institute, Houston, TX 77030, USA
| | - YiPing Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA Southern Center for Biomedical Research and Fujian Key Laboratory of Developmental and Neural Biology, College of Life Science, Fujian Normal University, Fuzhou, Fujian 350108, P.R. China
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10
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Sun C, Yu D, Ye W, Liu C, Gu S, Sinsheimer NR, Song Z, Li X, Chen C, Song Y, Wang S, Schrader L, Chen Y. The short stature homeobox 2 ( Shox2)-bone morphogenetic protein (BMP) pathway regulates dorsal mesenchymal protrusion development and its temporary function as a pacemaker during cardiogenesis. J Biol Chem 2014; 290:2007-23. [PMID: 25488669 DOI: 10.1074/jbc.m114.619007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The atrioventricular (AV) junction plays a critical role in chamber septation and transmission of cardiac conduction pulses. It consists of structures that develop from embryonic dorsal mesenchymal protrusion (DMP) and the embryonic AV canal. Despite extensive studies on AV junction development, the genetic regulation of DMP development remains poorly understood. In this study we present evidence that Shox2 is expressed in the developing DMP. Intriguingly, this Shox2-expressing domain possesses a pacemaker-specific genetic profile including Hcn4 and Tbx3. This genetic profile leads to nodal-like electrophysiological properties, which is gradually silenced as the AV node becomes matured. Phenotypic analyses of Shox2(-/-) mice revealed a hypoplastic and defectively differentiated DMP, likely attributed to increased apoptosis, accompanied by dramatically reduced expression of Bmp4 and Hcn4, ectopic activation of Cx40, and an aberrant pattern of action potentials. Interestingly, conditional deletion of Bmp4 or inhibition of BMP signaling by overexpression of Noggin using a Shox2-Cre allele led to a similar DMP hypoplasia and down-regulation of Hcn4, whereas activation of a transgenic Bmp4 allele in Shox2(-/-) background attenuated DMP defects. Moreover, the lack of Hcn4 expression in the DMP of mice carrying Smad4 conditional deletion and direct binding of pSmad1/5/8 to the Hcn4 regulatory region further confirm the Shox2-BMP genetic cascade in the regulation of DMP development. Our results reveal that Shox2 regulates DMP fate and development by controlling BMP signaling through the Smad-dependent pathway to drive tissue growth and to induce Hcn4 expression and suggest a temporal pacemaking function for the DMP during early cardiogenesis.
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Affiliation(s)
- Cheng Sun
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Diankun Yu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Wenduo Ye
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Chao Liu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Shuping Gu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Nathan R Sinsheimer
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Zhongchen Song
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Xihai Li
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Chun Chen
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Yingnan Song
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Shusheng Wang
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Laura Schrader
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - YiPing Chen
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
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Abstract
Background Inactivation of Shox2, a member of the short‐stature homeobox gene family, leads to defective development of multiple organs and embryonic lethality as a result of cardiovascular defects, including bradycardia and severe hypoplastic sinoatrial node (SAN) and sinus valves, in mice. It has been demonstrated that Shox2 regulates a genetic network through the repression of Nkx2.5 to maintain the fate of the SAN cells. However, the functional mechanism of Shox2 protein as a transcriptional repressor on Nkx2.5 expression remains completely unknown. Methods and Results A specific interaction between the B56δ regulatory subunit of PP2A and Shox2a, the isoform that is expressed in the developing heart, was demonstrated by yeast 2‐hybrid screen and coimmunoprecipitation. Western blotting and immunohistochemical assays further confirmed the presence of phosphorylated Shox2a (p‐Shox2a) in cell culture as well as in the developing mouse and human SAN. Site‐directed mutagenesis and in vitro kinase assays identified Ser92 and Ser110 as true phosphorylation sites and substrates of extracellular signal‐regulated kinase 1 and 2. Despite that Shox2a and its phosphorylation mutants possessed similar transcriptional repressive activities in cell cultures when fused with Gal4 protein, the mutant forms exhibited a compromised repressive effect on the activity of the mouse Nkx2.5 promoter in cell cultures, indicating that phosphorylation is required for Shox2a to repress Nkx2.5 expression specifically. Transgenic expression of Shox2a, but not Shox2a‐S92AS110A, mutant in the developing heart resulted in down‐regulation of Nkx2.5 in wild‐type mice and rescued the SAN defects in the Shox2 mutant background. Last, we demonstrated that elimination of both phosphorylation sites on Shox2a did not alter its nuclear location and dimerization, but depleted its capability to bind to the consensus sequences within the Nkx2.5 promoter region. Conclusions Our studies reveal that phosphorylation is essential for Shox2a to repress Nkx2.5 expression during SAN development and differentiation.
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Affiliation(s)
- Hongbing Liu
- Department of Cell and Molecular Biology, Tulane University, New Orleans, 70118, LA (H.L., C.H.C., W.Y., R.E.L., Y.P.C.)
| | - Chao-Hui Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, 70118, LA (H.L., C.H.C., W.Y., R.E.L., Y.P.C.)
| | - Wenduo Ye
- Department of Cell and Molecular Biology, Tulane University, New Orleans, 70118, LA (H.L., C.H.C., W.Y., R.E.L., Y.P.C.)
| | - Ramón A Espinoza-Lewis
- Department of Cell and Molecular Biology, Tulane University, New Orleans, 70118, LA (H.L., C.H.C., W.Y., R.E.L., Y.P.C.) Division of Cardiology, Children's Hospital Boston and Harvard Medical School, Boston, MA
| | - Xuefeng Hu
- Center for Biomedical Research of South China, Fujian Key Laboratory of Developmental and Neuro Biology, College of Life Science, Fujian Normal University, Fuzhou, Fujian Province, China (X.H., Y.Z., Y.P.C.)
| | - Yanding Zhang
- Center for Biomedical Research of South China, Fujian Key Laboratory of Developmental and Neuro Biology, College of Life Science, Fujian Normal University, Fuzhou, Fujian Province, China (X.H., Y.Z., Y.P.C.)
| | - YiPing Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, 70118, LA (H.L., C.H.C., W.Y., R.E.L., Y.P.C.) Center for Biomedical Research of South China, Fujian Key Laboratory of Developmental and Neuro Biology, College of Life Science, Fujian Normal University, Fuzhou, Fujian Province, China (X.H., Y.Z., Y.P.C.)
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Glaser A, Arora R, Hoffmann S, Li L, Gretz N, Papaioannou VE, Rappold GA. Tbx4 interacts with the short stature homeobox gene Shox2 in limb development. Dev Dyn 2014; 243:629-39. [PMID: 24347445 DOI: 10.1002/dvdy.24104] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 11/29/2013] [Accepted: 11/29/2013] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The short stature homeodomain transcription factors SHOX and SHOX2 play key roles in limb formation. To gain more insight into genes regulated by Shox2 during limb development, we analyzed expression profiles of WT and Shox2-/- mouse embryonic limbs and identified the T-Box transcription factor Tbx4 as a potential downstream target. Tbx4 is known to exert essential functions in skeletal and muscular hindlimb development. In humans, haploinsufficiency of TBX4 causes small patella syndrome, a skeletal dysplasia characterized by anomalies of the knee, pelvis, and foot. RESULTS Here, we demonstrate an inhibitory regulatory effect of Shox2 on Tbx4 specifically in the forelimbs. We also show that Tbx4 activates Shox2 expression in fore- and hindlimbs, suggesting Shox2 as a feedback modulator of Tbx4. Using EMSA studies, we find that Tbx4/TBX4 is able to bind to distinct T-box binding sites within the mouse and human Shox2/SHOX2 promoter. CONCLUSIONS Our data identifies Tbx4 as a novel transcriptional activator of Shox2 during murine fore- and hindlimb development. Tbx4 is also regulated by Shox2 specifically in the forelimb bud possibly via a feedback mechanism. These data extend our understanding of the role and regulation of Tbx4 and Shox2 in limb development and limb associated diseases.
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Affiliation(s)
- Anne Glaser
- Department of Human Molecular Genetics, University of Heidelberg, Heidelberg, Germany
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Sun C, Zhang T, Liu C, Gu S, Chen Y. Generation of Shox2-Cre allele for tissue specific manipulation of genes in the developing heart, palate, and limb. Genesis 2013; 51:515-22. [PMID: 23620086 DOI: 10.1002/dvg.22397] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 04/08/2013] [Accepted: 04/17/2013] [Indexed: 11/08/2022]
Abstract
Shox2 is expressed in several developing organs in a tissue specific manner in both mice and humans, including the heart, palate, limb, and nervous system. To better understand the spatial and temporal expression patterns of Shox2 and to systematically dissect the genetic cascade regulated by Shox2, we created Shox2-LacZ and Shox2-Cre knock-in mouse lines. We show that the Shox2-LacZ allele expresses beta-galactosidase reporter gene in a fashion that recapitulates the endogenous Shox2 expression pattern in developing organs, including the sinoatrial node (SAN), the anterior portion of the palate, and the proximal region of the limb bud. Conditional deletion of Shox2 in mice carrying the Shox2-Cre allele yielded SAN phenotypes that resemble conventional Shox2 knockout mice. Our results indicate that the Shox2-Cre allele offer a useful tool for tissue specific manipulation of genes in a number of developing organs, particularly in the developing SAN.
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Affiliation(s)
- Cheng Sun
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA
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