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Li J, Sun C, Zheng J, Li J, Yi G, Yang N. Time-Course Transcriptional and Chromatin Accessibility Profiling Reveals Genes Associated With Asymmetrical Gonadal Development in Chicken Embryos. Front Cell Dev Biol 2022; 10:832132. [PMID: 35345851 PMCID: PMC8957256 DOI: 10.3389/fcell.2022.832132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 02/09/2022] [Indexed: 12/02/2022] Open
Abstract
In birds, male gonads form on both sides whereas most females develop asymmetric gonads. Multiple early lines of evidence suggested that the right gonad fails to develop into a functional ovary, mainly due to differential expression of PITX2 in the gonadal epithelium. Despite some advances in recent years, the molecular mechanisms underlying asymmetric gonadal development remain unclear. Here, using bulk analysis of whole gonads, we established a relatively detailed profile of four representative stages of chicken gonadal development at the transcriptional and chromatin levels. We revealed that many candidate genes were significantly enriched in morphogenesis, meiosis and subcellular structure formation, which may be responsible for asymmetric gonadal development. Further chromatin accessibility analysis suggested that the transcriptional activities of the candidate genes might be regulated by nearby open chromatin regions, which may act as transcription factor (TF) binding sites and potential cis-regulatory elements. We found that LHX9 was a promising TF that bound to the left-biased peaks of many cell cycle-related genes. In summary, this study provides distinctive insights into the potential molecular basis underlying the asymmetric development of chicken gonads.
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Affiliation(s)
- Jianbo Li
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Congjiao Sun
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Jiangxia Zheng
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Junying Li
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Guoqiang Yi
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Ning Yang
- National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, China Agricultural University, Beijing, China
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2
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Shewale B, Dubois N. Of form and function: Early cardiac morphogenesis across classical and emerging model systems. Semin Cell Dev Biol 2021; 118:107-118. [PMID: 33994301 PMCID: PMC8434962 DOI: 10.1016/j.semcdb.2021.04.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/31/2022]
Abstract
The heart is the earliest organ to develop during embryogenesis and is remarkable in its ability to function efficiently as it is being sculpted. Cardiac heart defects account for a high burden of childhood developmental disorders with many remaining poorly understood mechanistically. Decades of work across a multitude of model organisms has informed our understanding of early cardiac differentiation and morphogenesis and has simultaneously opened new and unanswered questions. Here we have synthesized current knowledge in the field and reviewed recent developments in the realm of imaging, bioengineering and genetic technology and ex vivo cardiac modeling that may be deployed to generate more holistic models of early cardiac morphogenesis, and by extension, new platforms to study congenital heart defects.
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Affiliation(s)
- Bhavana Shewale
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Nicole Dubois
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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3
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Abstract
Cardiac development is a complex developmental process that is initiated soon after gastrulation, as two sets of precardiac mesodermal precursors are symmetrically located and subsequently fused at the embryonic midline forming the cardiac straight tube. Thereafter, the cardiac straight tube invariably bends to the right, configuring the first sign of morphological left–right asymmetry and soon thereafter the atrial and ventricular chambers are formed, expanded and progressively septated. As a consequence of all these morphogenetic processes, the fetal heart acquired a four-chambered structure having distinct inlet and outlet connections and a specialized conduction system capable of directing the electrical impulse within the fully formed heart. Over the last decades, our understanding of the morphogenetic, cellular, and molecular pathways involved in cardiac development has exponentially grown. Multiples aspects of the initial discoveries during heart formation has served as guiding tools to understand the etiology of cardiac congenital anomalies and adult cardiac pathology, as well as to enlighten novels approaches to heal the damaged heart. In this review we provide an overview of the complex cellular and molecular pathways driving heart morphogenesis and how those discoveries have provided new roads into the genetic, clinical and therapeutic management of the diseased hearts.
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4
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Spontaneous Left Cardiac Isomerism in Chick Embryos: Case Report, Review of the Literature, and Possible Significance for the Understanding of Ventricular Non-Compaction Cardiomyopathy in the Setting of Human Heterotaxy Syndromes. J Cardiovasc Dev Dis 2019; 6:jcdd6040040. [PMID: 31717331 PMCID: PMC6955803 DOI: 10.3390/jcdd6040040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 10/29/2019] [Accepted: 11/05/2019] [Indexed: 11/20/2022] Open
Abstract
The outer shape of most vertebrates is normally characterized by bilateral symmetry. The inner organs, on the other hand, are normally arranged in bilaterally asymmetric patterns. Congenital deviations from the normal organ asymmetry can occur in the form of mirror imagery of the normal arrangement (situs inversus), or in the form of arrangements that have the tendency for the development of bilateral symmetry, either in a pattern of bilateral left-sidedness (left isomerism) or bilateral right-sidedness (right isomerism). The latter two forms of visceral situs anomalies are called “heterotaxy syndromes”. During the past 30 years, remarkable progress has been made in uncovering the genetic etiology of heterotaxy syndromes. However, the pathogenetic mechanisms causing the spectrum of cardiovascular defects found in these syndromes remain poorly understood. In the present report, a spontaneous case of left cardiac isomerism found in an HH-stage 23 chick embryo is described. The observations made in this case confirmed the existence of molecular isomerism in the ventricular chambers previously noted in mouse models. They, furthermore, suggest that hearts with left cardiac isomerism may have the tendency for the development of non-compaction cardiomyopathy caused by defective development of the proepicardium.
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5
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Lozano-Velasco E, Garcia-Padilla C, Aránega AE, Franco D. Genetics of Atrial Fibrilation: In Search of Novel Therapeutic Targets. Cardiovasc Hematol Disord Drug Targets 2019; 19:183-194. [PMID: 30727926 DOI: 10.2174/1871529x19666190206150349] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 01/16/2019] [Accepted: 01/23/2019] [Indexed: 06/09/2023]
Abstract
Atrial fibrillation (AF) is the most frequent arrhythmogenic disease in humans, ranging from 2% in the general population and rising up to 10-12% in 80+ years. Genetic analyses of AF familiar cases have identified a series of point mutations in distinct ion channels, supporting a causative link. However, these genetic defects only explain a minority of AF patients. Genomewide association studies identified single nucleotide polymorphisms (SNPs), close to PITX2 on 4q25 chromosome, that are highly associated to AF. Subsequent GWAS studies have identified several new loci, involving additional transcription and growth factors. Furthermore, these risk 4q25 SNPs serve as surrogate biomarkers to identify AF recurrence in distinct surgical and pharmacological interventions. Experimental studies have demonstrated an intricate signalling pathway supporting a key role of the homeobox transcription factor PITX2 as a transcriptional regulator. Furthermore, cardiovascular risk factors such as hyperthyroidism, hypertension and redox homeostasis have been identified to modulate PITX2 driven gene regulatory networks. We provide herein a state-of-the-art review of the genetic bases of atrial fibrillation, our current understanding of the genetic regulatory networks involved in AF and its plausible usage for searching novel therapeutic targets.
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Affiliation(s)
- Estefanía Lozano-Velasco
- Cardiovascular Development Group, Department of Experimental Biology, University of Jaen, Jaen, Spain
| | - Carlos Garcia-Padilla
- Cardiovascular Development Group, Department of Experimental Biology, University of Jaen, Jaen, Spain
| | - Amelia E Aránega
- Cardiovascular Development Group, Department of Experimental Biology, University of Jaen, Jaen, Spain
| | - Diego Franco
- Cardiovascular Development Group, Department of Experimental Biology, University of Jaen, Jaen, Spain
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6
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Sivakumar A, Mahadevan A, Lauer ME, Narvaez RJ, Ramesh S, Demler CM, Souchet NR, Hascall VC, Midura RJ, Garantziotis S, Frank DB, Kimata K, Kurpios NA. Midgut Laterality Is Driven by Hyaluronan on the Right. Dev Cell 2018; 46:533-551.e5. [PMID: 30174180 PMCID: PMC6207194 DOI: 10.1016/j.devcel.2018.08.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 06/01/2018] [Accepted: 08/01/2018] [Indexed: 11/24/2022]
Abstract
For many years, biologists have focused on the role of Pitx2, expressed on the left side of developing embryos, in governing organ laterality. Here, we identify a different pathway during left-right asymmetry initiated by the right side of the embryo. Surprisingly, this conserved mechanism is orchestrated by the extracellular glycosaminoglycan, hyaluronan (HA) and is independent of Pitx2 on the left. Whereas HA is normally synthesized bilaterally as a simple polysaccharide, we show that covalent modification of HA by the enzyme Tsg6 on the right triggers distinct cell behavior necessary to drive the conserved midgut rotation and to pattern gut vasculature. HA disruption in chicken and Tsg6-/- mice results in failure to initiate midgut rotation and perturbs vascular development predisposing to midgut volvulus. Our study leads us to revise the current symmetry-breaking paradigm in vertebrates and demonstrates how enzymatic modification of HA matrices can execute the blueprint of organ laterality.
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Affiliation(s)
- Aravind Sivakumar
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Aparna Mahadevan
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Mark E Lauer
- Department of Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Ricky J Narvaez
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Siddesh Ramesh
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Cora M Demler
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Nathan R Souchet
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Vincent C Hascall
- Department of Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Ron J Midura
- Department of Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Stavros Garantziotis
- Division of Intramural Research, National Institute of Environmental Health Sciences, Research Triangle Park, Durham, NC, USA
| | - David B Frank
- Division of Pediatric Cardiology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Koji Kimata
- Institute of Molecular Medical Sciences, Aichi Medical University, Nagakute, Aichi, Japan
| | - Natasza A Kurpios
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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7
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Abstract
TGF-β family ligands function in inducing and patterning many tissues of the early vertebrate embryonic body plan. Nodal signaling is essential for the specification of mesendodermal tissues and the concurrent cellular movements of gastrulation. Bone morphogenetic protein (BMP) signaling patterns tissues along the dorsal-ventral axis and simultaneously directs the cell movements of convergence and extension. After gastrulation, a second wave of Nodal signaling breaks the symmetry between the left and right sides of the embryo. During these processes, elaborate regulatory feedback between TGF-β ligands and their antagonists direct the proper specification and patterning of embryonic tissues. In this review, we summarize the current knowledge of the function and regulation of TGF-β family signaling in these processes. Although we cover principles that are involved in the development of all vertebrate embryos, we focus specifically on three popular model organisms: the mouse Mus musculus, the African clawed frog of the genus Xenopus, and the zebrafish Danio rerio, highlighting the similarities and differences between these species.
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Affiliation(s)
- Joseph Zinski
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
| | - Benjamin Tajer
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
| | - Mary C Mullins
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6058
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8
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Multiple Roles of Pitx2 in Cardiac Development and Disease. J Cardiovasc Dev Dis 2017; 4:jcdd4040016. [PMID: 29367545 PMCID: PMC5753117 DOI: 10.3390/jcdd4040016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 10/02/2017] [Accepted: 10/03/2017] [Indexed: 12/14/2022] Open
Abstract
Cardiac development is a complex morphogenetic process initiated as bilateral cardiogenic mesoderm is specified at both sides of the gastrulating embryo. Soon thereafter, these cardiogenic cells fuse at the embryonic midline configuring a symmetrical linear cardiac tube. Left/right bilateral asymmetry is first detected in the forming heart as the cardiac tube bends to the right, and subsequently, atrial and ventricular chambers develop. Molecular signals emanating from the node confer distinct left/right signalling pathways that ultimately lead to activation of the homeobox transcription factor Pitx2 in the left side of distinct embryonic organ anlagen, including the developing heart. Asymmetric expression of Pitx2 has therefore been reported during different cardiac developmental stages, and genetic deletion of Pitx2 provided evidence of key regulatory roles of this transcription factor during cardiogenesis and thus congenital heart diseases. More recently, impaired Pitx2 function has also been linked to arrhythmogenic processes, providing novel roles in the adult heart. In this manuscript, we provide a state-of-the-art review of the fundamental roles of Pitx2 during cardiogenesis, arrhythmogenesis and its contribution to congenital heart diseases.
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9
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Sydow HG, Pieper T, Viebahn C, Tsikolia N. An Early Chick Embryo Culture Device for Extended Continuous Observation. Methods Mol Biol 2017; 1650:309-317. [PMID: 28809031 DOI: 10.1007/978-1-4939-7216-6_21] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Appropriate mechanical tension of the vitelline membrane as the culture substrate for the early chick embryo is frequently reported to be required for successful in vitro development. Here we describe a modified device, made of anodized aluminum, for in vitro culture which we used for studies of left-right symmetry breaking with emphasis on morphology and gene expression as readouts. The technique allows for easy, high-throughput tissue handling and provides a suitable tension in a stable and easily reproducible manner proven to be suitable for correct molecular left-right patterning and heart looping after long-term culture.
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Affiliation(s)
- Hans-Georg Sydow
- Anatomy and Embryology, University Medical Centre, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Tobias Pieper
- Anatomy and Embryology, University Medical Centre, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Christoph Viebahn
- Anatomy and Embryology, University Medical Centre, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Nikoloz Tsikolia
- Anatomy and Embryology, University Medical Centre, Kreuzbergring 36, 37075, Göttingen, Germany.
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10
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Genetic Regulation of Sinoatrial Node Development and Pacemaker Program in the Venous Pole. J Cardiovasc Dev Dis 2015; 2:282-298. [PMID: 26682210 PMCID: PMC4679406 DOI: 10.3390/jcdd2040282] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The definitive sinoatrial node (SAN), the primary pacemaker of the mammalian heart, develops from part of pro-pacemaking embryonic venous pole that expresses both Hcn4 and the transcriptional factor Shox2. It is noted that ectopic pacemaking activities originated from the myocardial sleeves of the pulmonary vein and systemic venous return, both derived from the Shox2+ pro-pacemaking cells in the venous pole, cause atrial fibrillation. However, the developmental link between the pacemaker properties in the embryonic venous pole cells and the SAN remains largely uncharacterized. Furthermore, the genetic program for the development of heterogeneous populations of the SAN is also under-appreciated. Here, we review the literature for a better understanding of the heterogeneous development of the SAN in relation to that of the sinus venosus myocardium and pulmonary vein myocardium. We also attempt to revisit genetic models pertinent to the development of pacemaker activities in the perspective of a Shox2-Nkx2-5 epistatic antagonism. Finally, we describe recent efforts in deciphering the regulatory networks for pacemaker development by genome-wide approaches.
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11
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Torlopp A, Khan MAF, Oliveira NMM, Lekk I, Soto-Jiménez LM, Sosinsky A, Stern CD. The transcription factor Pitx2 positions the embryonic axis and regulates twinning. eLife 2014; 3:e03743. [PMID: 25496870 PMCID: PMC4371885 DOI: 10.7554/elife.03743] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Accepted: 11/14/2014] [Indexed: 12/29/2022] Open
Abstract
Embryonic polarity of invertebrates, amphibians and fish is specified largely by maternal determinants, which fixes cell fates early in development. In contrast, amniote embryos remain plastic and can form multiple individuals until gastrulation. How is their polarity determined? In the chick embryo, the earliest known factor is cVg1 (homologous to mammalian growth differentiation factor 1, GDF1), a transforming growth factor beta (TGFβ) signal expressed posteriorly before gastrulation. A molecular screen to find upstream regulators of cVg1 in normal embryos and in embryos manipulated to form twins now uncovers the transcription factor Pitx2 as a candidate. We show that Pitx2 is essential for axis formation, and that it acts as a direct regulator of cVg1 expression by binding to enhancers within neighbouring genes. Pitx2, Vg1/GDF1 and Nodal are also key actors in left-right asymmetry, suggesting that the same ancient polarity determination mechanism has been co-opted to different functions during evolution.
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Affiliation(s)
- Angela Torlopp
- Department of Cell and
Developmental Biology, University College
London, London, United Kingdom
| | - Mohsin A F Khan
- Department of Cell and
Developmental Biology, University College
London, London, United Kingdom
| | - Nidia M M Oliveira
- Department of Cell and
Developmental Biology, University College
London, London, United Kingdom
| | - Ingrid Lekk
- Department of Cell and
Developmental Biology, University College
London, London, United Kingdom
| | - Luz Mayela Soto-Jiménez
- Department of Cell and
Developmental Biology, University College
London, London, United Kingdom
- Programa de Ciencias
Genómicas, Universidad Nacional Autónoma de
México, Morelos, Mexico
| | - Alona Sosinsky
- Institute of Structural
and Molecular Biology, Birkbeck College, University of
London, London, United Kingdom
| | - Claudio D Stern
- Department of Cell and
Developmental Biology, University College
London, London, United Kingdom
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12
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Ahnfelt-Rønne J, Ravassard P, Pardanaud-Glavieux C, Scharfmann R, Serup P. Mesenchymal bone morphogenetic protein signaling is required for normal pancreas development. Diabetes 2010; 59:1948-56. [PMID: 20522595 PMCID: PMC2911072 DOI: 10.2337/db09-1010] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Pancreas organogenesis is orchestrated by interactions between the epithelium and the mesenchyme, but these interactions are not completely understood. Here we investigated a role for bone morphogenetic protein (BMP) signaling within the pancreas mesenchyme and found it to be required for the normal development of the mesenchyme as well as for the pancreatic epithelium. RESEARCH DESIGN AND METHODS We analyzed active BMP signaling by immunostaining for phospho-Smad1,5,8 and tested whether pancreas development was affected by BMP inhibition after expression of Noggin and dominant negative BMP receptors in chicken and mouse pancreas. RESULTS Endogenous BMP signaling is confined to the mesenchyme in the early pancreas and inhibition of BMP signaling results in severe pancreatic hypoplasia with reduced epithelial branching. Notably, we also observed an excessive endocrine differentiation when mesenchymal BMP signaling is blocked, presumably secondary to defective mesenchyme to epithelium signaling. CONCLUSIONS We conclude that BMP signaling plays a previously unsuspected role in the mesenchyme, required for normal development of the mesenchyme as well as for the epithelium.
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Affiliation(s)
| | - Philippe Ravassard
- Biotherapy and Biotechnology Laboratory, Centre de Recherche de l'Institut du Cerveau et de la Moelle, University Pierre et Marie Curie, Paris, France
| | - Corinne Pardanaud-Glavieux
- Biotherapy and Biotechnology Laboratory, Centre de Recherche de l'Institut du Cerveau et de la Moelle, University Pierre et Marie Curie, Paris, France
| | - Raphaél Scharfmann
- Centre de Recherche Croissance et Signalisation, Université Paris Descartes, Faculté de Médecine, Hôpital Necker, Paris, France
| | - Palle Serup
- Hagedorn Research Institute, Gentofte, Denmark
- Corresponding author: Palle Serup,
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13
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Zhang Y, Levin M. Left-right asymmetry in the chick embryo requires core planar cell polarity protein Vangl2. Genesis 2009; 47:719-28. [PMID: 19621439 PMCID: PMC2790031 DOI: 10.1002/dvg.20551] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Consistent left-right patterning is a fascinating and biomedically important problem. In the chick embryo, it is not known how cells determine their position (left or right) relative to the primitive streak, which is required for subsequent asymmetric gene expression cascades. We show that the subcellular localization of Vangl2, a core planar cell polarity (PCP) protein, is consistently polarized, giving cells in the blastoderm a vector pointing toward the primitive streak. Moreover, morpholino-mediated loss-of-function of Vangl2 by electroporation into chicks at very early stages randomizes the normally left-sided expression of Sonic hedgehog. Strikingly, Vangl2 morpholinos also induce a desynchronization of asymmetric gene expression within the left and right domains of Hensen's node. These data reveal the existence of polarized planar cell polarity protein localization in gastrulating chick and demonstrate that the PCP pathway is functionally required for normal asymmetry in the chick upstream of Sonic hedgehog. These data suggest a new and widely applicable class of models for the spread and coordination of left-right patterning information in the embryonic blastoderm.
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Affiliation(s)
- Ying Zhang
- Center for Regenerative and Developmental Biology The Forsyth Institute, and Department of Developmental Biology Harvard School of Dental Medicine, 140 The Fenway Boston, MA 02115, U.S.A
| | - Michael Levin
- Center for Regenerative and Developmental Biology The Forsyth Institute, and Department of Developmental Biology Harvard School of Dental Medicine, 140 The Fenway Boston, MA 02115, U.S.A
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14
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Simard A, Di Giorgio L, Amen M, Westwood A, Amendt BA, Ryan AK. The Pitx2c N-terminal domain is a critical interaction domain required for asymmetric morphogenesis. Dev Dyn 2009; 238:2459-70. [PMID: 19681163 PMCID: PMC3014603 DOI: 10.1002/dvdy.22062] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The paired-like homeodomain transcription factor Pitx2c has an essential role in patterning the left-right axis. However, neither its transcriptional targets nor the molecular mechanisms through which it exerts its patterning function are known. Here we provide evidence that the N-terminal domain of Pitx2c is important for this activity. Overexpression of the Pitx2c N-terminus in ovo randomizes the direction of heart looping, the first morphological asymmetry conserved in vertebrate embryos. In addition, the Pitx2c N-terminal domain blocks the ability of Pitx2c to synergize with Nkx2.5 to transactivate the procollagen lysyl hydroxylase (Plod-1) promoter in transient transfection assays. A five amino acid region containing leucine-41 is required for both of these effects. Our data suggest that the Pitx2c N-terminal domain competes with endogenous Pitx2c for binding to a protein interaction partner that is required for the activation of genes that direct asymmetric morphogenesis along the left-right axis.
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Affiliation(s)
- Annie Simard
- The Research Institute of the McGill University Health Center, Montreal, Quebec
| | | | - Melanie Amen
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX
| | - Ashley Westwood
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX
| | - Brad A. Amendt
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX
| | - Aimee K. Ryan
- The Research Institute of the McGill University Health Center, Montreal, Quebec
- Department of Human Genetics, McGill University, Montreal, Quebec
- Department of Pediatrics, McGill University, Montreal, Quebec
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15
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Blum M, Beyer T, Weber T, Vick P, Andre P, Bitzer E, Schweickert A. Xenopus, an ideal model system to study vertebrate left-right asymmetry. Dev Dyn 2009; 238:1215-25. [DOI: 10.1002/dvdy.21855] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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16
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Schlueter J, Brand T. A right-sided pathway involving FGF8/Snai1 controls asymmetric development of the proepicardium in the chick embryo. Proc Natl Acad Sci U S A 2009; 106:7485-90. [PMID: 19365073 PMCID: PMC2678653 DOI: 10.1073/pnas.0811944106] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Indexed: 01/30/2023] Open
Abstract
The proepicardium (PE) is a transient structure that forms at the venous pole of the embryonic vertebrate heart. This cardiac progenitor cell population gives rise to the epicardium, coronary vasculature, and fibroblasts. In the chicken embryo, the PE displays left-right (L-R) asymmetry and develops only on the right side, while on the left only a vestigial PE is formed, which subsequently gets lost by apoptosis. In this study, we analyzed how the L-R asymmetry pathway affects PE formation. Experimental manipulation of left-side determinants such as Shh, Nodal, and Cfc as well as forced expression of Pitx2 had no effect on the sidedness of PE development. In contrast, inhibition of early-acting regulators of L-R axis formation such as H(+)/K(+)-ATPase or primitive streak apoptosis affected the sidedness of PE development. Experimental interference with the right-side determinants Fgf8 or Snai1 prevented PE formation, whereas ectopic left-sided expression of Fgf8 or Snai1 resulted in bilateral PE development. These data provide novel insight into the molecular control of asymmetric morphogenesis suggesting that also the right side harbors an instructive signaling pathway that is involved in the control of PE development. This pathway might be of general relevance for setting up L-R asymmetries at the venous pole of the heart.
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Affiliation(s)
- Jan Schlueter
- Cell and Developmental Biology, University of Würzburg, Biocenter, Am Hubland, 97974 Würzburg, Germany
| | - Thomas Brand
- Cell and Developmental Biology, University of Würzburg, Biocenter, Am Hubland, 97974 Würzburg, Germany
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Rostral paraxial mesoderm regulates refinement of the eye field through the bone morphogenetic protein (BMP) pathway. Dev Biol 2009; 330:389-98. [PMID: 19362544 DOI: 10.1016/j.ydbio.2009.04.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 03/27/2009] [Accepted: 04/06/2009] [Indexed: 11/24/2022]
Abstract
The eye field is initially a large single domain at the anterior end of the neural plate and is the first indication of optic potential in the vertebrate embryo. During the course of development, this domain is subject to interactions that shape and refine the organogenic field. The action of the prechordal mesoderm in bisecting this single region into two bilateral domains has been well described, however the role of signalling interactions in the further restriction and refinement of this domain has not been previously characterised. Here we describe a role for the rostral cephalic paraxial mesoderm in limiting the extent of the eye field. The anterior transposition of this mesoderm or its ablation disrupted normal development of the eye. Importantly, perturbation of optic vesicle development occurred in the absence of any detectable changes in the pattern of neighbouring regions of the neural tube. Furthermore, negative regulation of eye development is a property unique to the rostral paraxial mesoderm. The rostral paraxial mesoderm expresses members of the bone morphogenetic protein (BMP) family of signalling molecules and manipulation of endogenous BMP signalling resulted in abnormalities of the early optic primordia.
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18
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Sonic hedgehog maintains proliferation in secondary heart field progenitors and is required for normal arterial pole formation. Dev Biol 2009; 330:305-17. [PMID: 19361493 DOI: 10.1016/j.ydbio.2009.03.028] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 03/10/2009] [Accepted: 03/31/2009] [Indexed: 01/16/2023]
Abstract
The Sonic hedgehog (Shh)-null mouse was initially described as a phenotypic mimic of Tetralogy of Fallot with pulmonary atresia (Washington Smoak, I., Byrd, N.A., Abu-Issa, R., Goddeeris, M.M., Anderson, R., Morris, J., Yamamura, K., Klingensmith, J., and Meyers, E.N. 2005. Sonic hedgehog is required for cardiac outflow tract and neural crest cell development. Dev. Biol. 283, 357-372.); however, subsequent reports describe only a single outflow tract, leaving the phenotype and its developmental mechanism unclear. We hypothesized that the phenotype that occurs in response to Shh knockdown is pulmonary atresia and is directly related to the abnormal development of the secondary heart field. We found that Shh was expressed by the pharyngeal endoderm adjacent to the secondary heart field and that its receptor Ptc2 was expressed in a gradient in the secondary heart field, with the most robust expression in the caudal secondary heart field, closest to the Shh expression. In vitro culture of secondary heart field with the hedgehog inhibitor cyclopamine significantly reduced proliferation. In ovo, cyclopamine treatment before the secondary heart field adds to the outflow tract reduced proliferation only in the caudal secondary heart field, which coincided with the region of high Ptc2 expression. After outflow tract septation should occur, embryos treated with cyclopamine exhibited pulmonary atresia, pulmonary stenosis, and persistent truncus arteriosus. In hearts with pulmonary atresia, cardiac neural crest-derived cells, which form the outflow tract septum, migrated into the outflow tract and formed a septum. However, this septum divided the outflow tract into two unequal sized vessels and effectively closed off the pulmonary outlet. These experiments show that Shh is necessary for secondary heart field proliferation, which is required for normal pulmonary trunk formation, and that embryos with pulmonary atresia have an outflow tract septum.
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Yu X, He F, Zhang T, Espinoza-Lewis RA, Lin L, Yang J, Chen Y. Cerberus functions as a BMP agonist to synergistically induce nodal expression during left-right axis determination in the chick embryo. Dev Dyn 2009; 237:3613-23. [PMID: 18985739 DOI: 10.1002/dvdy.21769] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Left-sided expression of Nodal in the lateral plate mesoderm (LPM) during early embryogenesis is a crucial step in establishing the left-right (L-R) axis in vertebrates. In the chick, it was suggested that chick Cerberus (cCer), a Cerberus/Dan family member, induces Nodal expression by antagonizing bone morphogenetic protein (BMP) activity in the left LPM. In contrast, it has also been shown that BMPs positively regulate Nodal expression in the left LPM in the chick embryo. Thus, it is still unclear how the bilaterally expressed BMPs induce Nodal expression only in the left LPM. In this study, we demonstrate that BMP signaling is necessary and sufficient for the induction of Nodal expression in the chick LPM where the type I BMP receptor-IB (BMPR-IB) likely mediates this induction. Tissue grafting experiments indicate the existence of a Nodal inductive factor in the left LPM rather than the presence of a Nodal inhibitory factor in the right LPM. We demonstrate that cCer functions as a BMP agonist instead of antagonist, being able to enhance BMP signaling in cell culture. This conclusion is further supported by the immunoprecipitation assays that provide convincing biochemical evidence for a direct interaction between cCer and BMP receptor. Because cCer is expressed restrictedly in the left LPM, BMPs and cCer appear to act synergistically to activate Nodal expression in the left LPM in the chick.
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Affiliation(s)
- Xueyan Yu
- Section of Oral Biology, The Ohio State University College of Dentistry, Columbus, Ohio 43210, USA.
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20
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Ishimura A, Chida S, Osada SI. Man1, an inner nuclear membrane protein, regulates left-right axis formation by controlling nodal signaling in a node-independent manner. Dev Dyn 2008; 237:3565-76. [DOI: 10.1002/dvdy.21663] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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21
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Rodríguez-León J, Esteban CR, Martí M, Santiago-Josefat B, Dubova I, Rubiralta X, Belmonte JCI. Pitx2 regulates gonad morphogenesis. Proc Natl Acad Sci U S A 2008; 105:11242-7. [PMID: 18678914 PMCID: PMC2516275 DOI: 10.1073/pnas.0804904105] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Indexed: 12/17/2022] Open
Abstract
Organ shape and size, and, ultimately, organ function, relate in part to the cell and tissue spatial arrangement that takes place during embryonic development. Despite great advances in the genetic regulatory networks responsible for tissue and organ development, it is not yet clearly understood how specific gene functions are linked to the specific morphogenetic processes underlying the internal organ asymmetries found in vertebrate animals. During female chick embryogenesis, and in contrast to males where both testes develop symmetrically, asymmetrical gonad morphogenesis results in only one functional ovary. The disposition of paired organs along the left-right body axis has been shown to be regulated by the activity of the homeobox containing gene pitx2. We have found that pitx2 regulates cell adhesion, affinity, and cell recognition events in the developing gonad primordium epithelia. This in turn not only allows for proper somatic development of the gonad cortex but also permits the proliferation and differentiation of primordial germ cells. We illustrate how Pitx2 activity directs asymmetrical gonad morphogenesis by controlling mitotic spindle orientation of the developing gonad cortex and how, by modulating cyclinD1 expression during asymmetric ovarian development, Pitx2 appears to control gonad organ size. All together our observations indicate that the effects elicited by Pitx2 during the development of the female chick ovary are critical for cell topology, growth, fate, and ultimately organ morphogenesis and function.
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Affiliation(s)
- Joaquín Rodríguez-León
- *Center of Regenerative Medicine in Barcelona, Doctor Aiguader 88, 08003 Barcelona, Spain; and
| | - Concepción Rodríguez Esteban
- Gene Expression Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037
| | - Mercè Martí
- *Center of Regenerative Medicine in Barcelona, Doctor Aiguader 88, 08003 Barcelona, Spain; and
| | - Belén Santiago-Josefat
- *Center of Regenerative Medicine in Barcelona, Doctor Aiguader 88, 08003 Barcelona, Spain; and
| | - Ilir Dubova
- *Center of Regenerative Medicine in Barcelona, Doctor Aiguader 88, 08003 Barcelona, Spain; and
- Gene Expression Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037
| | - Xavier Rubiralta
- *Center of Regenerative Medicine in Barcelona, Doctor Aiguader 88, 08003 Barcelona, Spain; and
- Gene Expression Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037
| | - Juan Carlos Izpisúa Belmonte
- *Center of Regenerative Medicine in Barcelona, Doctor Aiguader 88, 08003 Barcelona, Spain; and
- Gene Expression Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037
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22
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Davis NM, Kurpios NA, Sun X, Gros J, Martin JF, Tabin CJ. The chirality of gut rotation derives from left-right asymmetric changes in the architecture of the dorsal mesentery. Dev Cell 2008; 15:134-45. [PMID: 18606147 PMCID: PMC2528248 DOI: 10.1016/j.devcel.2008.05.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 04/12/2008] [Accepted: 05/01/2008] [Indexed: 01/28/2023]
Abstract
We have investigated the structural basis by which the counterclockwise direction of the amniote gut is established. The chirality of midgut looping is determined by left-right asymmetries in the cellular architecture of the dorsal mesentery, the structure that connects the primitive gut tube to the body wall. The mesenchymal cells of the dorsal mesentery are more condensed on the left side than on the right and, additionally, the overlying epithelium on the left side exhibits a columnar morphology, in contrast to a cuboidal morphology on the right. These properties are instructed by a set of transcription factors: Pitx2 and Isl1 specifically expressed on the left side, and Tbx18 expressed on the right, regulated downstream of the secreted protein Nodal which is present exclusively on the left side. The resultant differences in cellular organization cause the mesentery to assume a trapezoidal shape, tilting the primitive gut tube leftward.
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Affiliation(s)
- Nicole M Davis
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
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23
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Raya Á, Izpisúa Belmonte JC. Insights into the establishment of left–right asymmetries in vertebrates. ACTA ACUST UNITED AC 2008; 84:81-94. [DOI: 10.1002/bdrc.20122] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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24
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Dakubo GD, Mazerolle C, Furimsky M, Yu C, St-Jacques B, McMahon AP, Wallace VA. Indian hedgehog signaling from endothelial cells is required for sclera and retinal pigment epithelium development in the mouse eye. Dev Biol 2008; 320:242-55. [PMID: 18582859 DOI: 10.1016/j.ydbio.2008.05.528] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 05/02/2008] [Accepted: 05/08/2008] [Indexed: 01/21/2023]
Abstract
The development of extraocular orbital structures, in particular the choroid and sclera, is regulated by a complex series of interactions between neuroectoderm, neural crest and mesoderm derivatives, although in many instances the signals that mediate these interactions are not known. In this study we have investigated the function of Indian hedgehog (Ihh) in the developing mammalian eye. We show that Ihh is expressed in a population of non-pigmented cells located in the developing choroid adjacent to the RPE. The analysis of Hh mutant mice demonstrates that the RPE and developing scleral mesenchyme are direct targets of Ihh signaling and that Ihh is required for the normal pigmentation pattern of the RPE and the condensation of mesenchymal cells to form the sclera. Our findings also indicate that Ihh signals indirectly to promote proliferation and photoreceptor specification in the neural retina. This study identifies Ihh as a novel choroid-derived signal that regulates RPE, sclera and neural retina development.
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Affiliation(s)
- Gabriel D Dakubo
- University of Ottawa Eye Institute, 451 Smyth Road, Ottawa, ON, Canada K1H 8M5
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25
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Guioli S, Lovell-Badge R. PITX2 controls asymmetric gonadal development in both sexes of the chick and can rescue the degeneration of the right ovary. Development 2007; 134:4199-208. [PMID: 17959721 DOI: 10.1242/dev.010249] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The gonads arise on the ventromedial surface of each mesonephros. In most birds, female gonadal development is unusual in that only the left ovary becomes functional, whereas that on the right degenerates during embryogenesis. Males develop a pair of equally functional testes. We show that the chick gonads already have distinct morphological and molecular left-right (L-R) characteristics in both sexes at indifferent (genital ridge) stages and that these persist, becoming more elaborate during sex determination and differentiation, but have no consequences for testis differentiation. We find that these L-R differences depend on the L-R asymmetry pathway that controls the situs of organs such as the heart and gut. Moreover, a key determinant of this, Pitx2, is expressed asymmetrically, such that it is found only in the left gonad in both sexes from the start of their development. Misexpression of Pitx2 on the right side before and during gonadogenesis is sufficient to transform the right gonad into a left-like gonad. In ZW embryos, this transformation rescues the degenerative fate of the right ovary, allowing for the differentiation of left-like cortex containing meiotic germ cells. There is therefore a mechanism in females that actively promotes the underlying L-R asymmetry initiated by Pitx2 and the degeneration of the right gonad, and a mechanism in males that allows it to be ignored or overridden.
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Affiliation(s)
- Silvana Guioli
- Division of Stem Cell Biology and Developmental Genetics, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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26
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Schlueter J, Brand T. Left-right axis development: examples of similar and divergent strategies to generate asymmetric morphogenesis in chick and mouse embryos. Cytogenet Genome Res 2007; 117:256-67. [PMID: 17675867 DOI: 10.1159/000103187] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Accepted: 08/24/2006] [Indexed: 12/18/2022] Open
Abstract
Left-right asymmetry of internal organs is widely distributed in the animal kingdom. The chick and mouse embryos have served as important model organisms to analyze the mechanisms underlying the establishment of the left-right axis. In the chick embryo many genes have been found to be asymmetrically expressed in and around the node, while the same genes in the mouse show symmetric expression patterns. In the mouse there is strong evidence for an establishment of left-right asymmetry through nodal cilia. In contrast, in the chick and in many other organisms left-right asymmetry is probably generated by an early-acting event involving membrane depolarization. In both birds and mammals a conserved Nodal-Lefty-Pitx2 module exists that controls many aspects of asymmetric morphogenesis. This review also gives examples of divergent mechanisms of establishing asymmetric organ formation. Thus there is ample evidence for conserved and non-conserved strategies to generate asymmetry in birds and mammals.
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Affiliation(s)
- J Schlueter
- Cell and Developmental Biology, University of Würzburg, Würzburg, Germany
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27
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Wang S, He F, Xiong W, Gu S, Liu H, Zhang T, Yu X, Chen Y. Polycomblike-2-deficient mice exhibit normal left–right asymmetry. Dev Dyn 2007; 236:853-61. [PMID: 17266133 DOI: 10.1002/dvdy.21070] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Polycomb group (PcG) proteins are required for maintaining the repressed state of developmentally important genes such as homeotic genes. Polycomblike (Pcl), a member of PcG genes with two characteristic PHD finger motifs, was shown to strongly enhance the effects of PcG genes in Drosophila. Three Pcl genes exist in the mouse genome, with their function largely unknown. Our previous studies demonstrate that the chick Pcl2 is essential for the left-right asymmetry by silencing Shh expression in the right side of the node (Wang et al., [2004b] Development 131:4381-4391). To elucidate the in vivo role of mouse Pcl2, we generated Pcl2 mutant mice. Phenotypic analyses indicate the normal development of left-right asymmetry in the Pcl2 mutant mice. However, Pcl2 mutant mice exhibit posterior transformation of axial skeletons and other phenotypic defects, with a relatively low penetrance. These results demonstrate that Pcl2 is dispensable for the normal left-right axis development in mice.
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Affiliation(s)
- Shusheng Wang
- Division of Developmental Biology, Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA
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28
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Maeda R, Hozumi S, Taniguchi K, Sasamura T, Murakami R, Matsuno K. Roles of single-minded in the left-right asymmetric development of the Drosophila embryonic gut. Mech Dev 2006; 124:204-17. [PMID: 17241775 DOI: 10.1016/j.mod.2006.12.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2006] [Revised: 11/14/2006] [Accepted: 12/08/2006] [Indexed: 11/20/2022]
Abstract
Many animals have genetically determined left-right (LR) asymmetry of their internal organs. The midline structure of vertebrate embryos has important roles in LR asymmetric development both as the signaling center for LR asymmetry and as a barrier to inappropriate LR signaling across the midline. However, in invertebrates, the functions of the midline in LR asymmetric development are unknown. To elucidate these roles, we studied the involvement of single-minded (sim) in the LR asymmetry of the Drosophila embryonic gut, which develops in a stereotypic, asymmetric manner. sim encodes a bHLH/PAS transcription factor that is required for the development of the ventral midline structure. Here we report that sim was expressed in the midline of the foregut and hindgut primordia. The handedness of the embryonic gut was affected in sim mutant embryos and in embryos overexpressing sim. However, midline-derived events, which involve Slit/Robo and EGFr signaling and direct the development of the tissues adjacent to the midline, did not affect the laterality of this organ, suggesting a crucial role for the midline itself in LR asymmetry. In the sim mutants, the midline structures of the embryonic anal pad were deformed. The mis-expression of sim in the anal-pad primordium induced LR defects. We also found that different portions of the embryonic gut require sim functions at different times for normal LR asymmetry. Our results suggest that the midline structures are involved in the LR asymmetric development of the Drosophila embryonic gut.
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Affiliation(s)
- Reo Maeda
- Department of Biological Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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29
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Depew MJ, Simpson CA. 21st century neontology and the comparative development of the vertebrate skull. Dev Dyn 2006; 235:1256-91. [PMID: 16598716 DOI: 10.1002/dvdy.20796] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Classic neontology (comparative embryology and anatomy), through the application of the concept of homology, has demonstrated that the development of the gnathostome (jawed vertebrate) skull is characterized both by a fidelity to the gnathostome bauplan and the exquisite elaboration of final structural design. Just as homology is an old concept amended for modern purposes, so are many of the questions regarding the development of the skull. With due deference to Geoffroy-St. Hilaire, Cuvier, Owen, Lankester et al., we are still asking: How are bauplan fidelity and elaboration of design maintained, coordinated, and modified to generate the amazing diversity seen in cranial morphologies? What establishes and maintains pattern in the skull? Are there universal developmental mechanisms underlying gnathostome autapomorphic structural traits? Can we detect and identify the etiologies of heterotopic (change in the topology of a developmental event), heterochronic (change in the timing of a developmental event), and heterofacient (change in the active capacetence, or the elaboration of capacity, of a developmental event) changes in craniofacial development within and between taxa? To address whether jaws are all made in a like manner (and if not, then how not), one needs a starting point for the sake of comparison. To this end, we present here a "hinge and caps" model that places the articulation, and subsequently the polarity and modularity, of the upper and lower jaws in the context of cranial neural crest competence to respond to positionally located epithelial signals. This model expands on an evolving model of polarity within the mandibular arch and seeks to explain a developmental patterning system that apparently keeps gnathostome jaws in functional registration yet tractable to potential changes in functional demands over time. It relies upon a system for the establishment of positional information where pattern and placement of the "hinge" is driven by factors common to the junction of the maxillary and mandibular branches of the first arch and of the "caps" by the signals emanating from the distal-most first arch midline and the lamboidal junction (where the maxillary branch meets the frontonasal processes). In this particular model, the functional registration of jaws is achieved by the integration of "hinge" and "caps" signaling, with the "caps" sharing at some critical level a developmental history that potentiates their own coordination. We examine the evidential foundation for this model in mice, examine the robustness with which it can be applied to other taxa, and examine potential proximate sources of the signaling centers. Lastly, as developmental biologists have long held that the anterior-most mesendoderm (anterior archenteron roof or prechordal plate) is in some way integral to the normal formation of the head, including the cranial skeletal midlines, we review evidence that the seminal patterning influences on the early anterior ectoderm extend well beyond the neural plate and are just as important to establishing pattern within the cephalic ectoderm, in particular for the "caps" that will yield medial signaling centers known to coordinate jaw development.
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Affiliation(s)
- Michael J Depew
- Department of Craniofacial Development, King's College London, Guy's Hospital, London Bridge, London, United Kingdom.
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30
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Levin M. Is the early left-right axis like a plant, a kidney, or a neuron? The integration of physiological signals in embryonic asymmetry. ACTA ACUST UNITED AC 2006; 78:191-223. [PMID: 17061264 DOI: 10.1002/bdrc.20078] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Embryonic morphogenesis occurs along three orthogonal axes. While the patterning of the anterior-posterior and dorsal-ventral axes has been increasingly well-characterized, the left-right (LR) axis has only relatively recently begun to be understood at the molecular level. The mechanisms that ensure invariant LR asymmetry of the heart, viscera, and brain involve fundamental aspects of cell biology, biophysics, and evolutionary biology, and are important not only for basic science but also for the biomedicine of a wide range of birth defects and human genetic syndromes. The LR axis links biomolecular chirality to embryonic development and ultimately to behavior and cognition, revealing feedback loops and conserved functional modules occurring as widely as plants and mammals. This review focuses on the unique and fascinating physiological aspects of LR patterning in a number of vertebrate and invertebrate species, discusses several profound mechanistic analogies between biological regulation in diverse systems (specifically proposing a nonciliary parallel between kidney cells and the LR axis based on subcellular regulation of ion transporter targeting), highlights the possible importance of early, highly-conserved intracellular events that are magnified to embryo-wide scales, and lays out the most important open questions about the function, evolutionary origin, and conservation of mechanisms underlying embryonic asymmetry.
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Affiliation(s)
- Michael Levin
- Forsyth Center for Regenerative and Developmental Biology, The Forsyth Institute, and the Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts 02115, USA.
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Bajoghli B, Aghaallaei N, Soroldoni D, Czerny T. The roles of Groucho/Tle in left-right asymmetry and Kupffer's vesicle organogenesis. Dev Biol 2006; 303:347-61. [PMID: 17188260 DOI: 10.1016/j.ydbio.2006.11.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 11/06/2006] [Accepted: 11/14/2006] [Indexed: 01/22/2023]
Abstract
The heart is the first organ to form and function in the vertebrate embryo. Furthermore, differences between the left and right sides of the embryo become first detectable during cardiac development. We observed strong cardiac laterality phenotypes in medaka embryos by manipulating Groucho protein activity. The phenotypes produced by misexpressing Tle4 and the dominant-negative Aes reveal a general effect of these corepressor proteins on left-right (LR) development. With the help of an inducible expression system, we were able to define temporally different phases for these effects. In an early phase during gastrulation, Groucho proteins regulate Brachyury expression in the dorsal forerunner cells, which later gives rise to the Kupffer's vesicle (KV). The interference of endogenous Groucho proteins by misexpression of Aes leads to KVs of reduced size, whereas overexpression of Tle4 results in enlarged KVs. The expression level of the cilia marker Lrd was also affected both positively and negatively from these treatments. In the late phase during somitogenesis, Groucho proteins regulate the asymmetric activities of Nodal and Lefty genes. Altering canonical Wnt signaling produced similar results in late embryos, however, this did not affect KV morphogenesis or Lrd expression in early embryos. Therefore, changes in Kupffer's vesicle morphogenesis and the laterality of visceral organs following alterations in Groucho corepressor levels demonstrate two distinct phases in which Groucho proteins help establish LR asymmetry in medaka fish.
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Affiliation(s)
- Baubak Bajoghli
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Veterinärplatz 1, A-1210 Vienna, Austria
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32
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Gerhart J, Elder J, Neely C, Schure J, Kvist T, Knudsen K, George-Weinstein M. MyoD-positive epiblast cells regulate skeletal muscle differentiation in the embryo. J Cell Biol 2006; 175:283-92. [PMID: 17060497 PMCID: PMC2064569 DOI: 10.1083/jcb.200605037] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Accepted: 09/15/2006] [Indexed: 11/22/2022] Open
Abstract
MyoD mRNA is expressed in a subpopulation of cells within the embryonic epiblast. Most of these cells are incorporated into somites and synthesize Noggin. Ablation of MyoD-positive cells in the epiblast subsequently results in the herniation of organs through the ventral body wall, a decrease in the expression of Noggin, MyoD, Myf5, and myosin in the somites and limbs, and an increase in Pax-3-positive myogenic precursors. The addition of Noggin lateral to the somites compensates for the loss of MyoD-positive epiblast cells. Skeletal muscle stem cells that arise in the epiblast are utilized in the somites to promote muscle differentiation by serving as a source of Noggin.
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Affiliation(s)
- Jacquelyn Gerhart
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA 19131, USA
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33
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Bothe I, Dietrich S. The molecular setup of the avian head mesoderm and its implication for craniofacial myogenesis. Dev Dyn 2006; 235:2845-60. [PMID: 16894604 DOI: 10.1002/dvdy.20903] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The head mesoderm is the mesodermal tissue on either side of the brain, from forebrain to hindbrain levels, and gives rise to the genuine head muscles. Its relatedness to the more posterior paraxial mesoderm, the somites, which generate the muscles of the trunk, is conversely debated. To gain insight into the molecular setup of the head mesoderm, its similarity or dissimilarity to the somitic mesoderm, and the implications of its setup for the progress of muscle formation, we investigated the expression of markers (1) for mesoderm segmentation and boundary formation, (2) for regional specification and somitogenesis and (3) for the positive and negative control of myogenic differentiation. We show that the head mesoderm is molecularly distinct from somites. It is not segmented; even the boundary to the first somite is ill-defined. Importantly, the head mesoderm lacks the transcription factors driving muscle differentiation while genes suppressing differentiation and promoting cell proliferation are expressed. These factors show anteroposteriorly and dorsoventrally regionalised but overlapping expression. Notably, expression extends into the areas that actively contribute to the heart, overlapping with the expression of cardiac markers.
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Affiliation(s)
- Ingo Bothe
- King's College London, Department of Craniofacial Development, Guy's Hospital, London, United Kingdom
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34
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Ellertsdottir E, Ganz J, Dürr K, Loges N, Biemar F, Seifert F, Ettl AK, Kramer-Zucker AK, Nitschke R, Driever W. A mutation in the zebrafish Na,K-ATPase subunitatp1a1a.1provides genetic evidence that the sodium potassium pump contributes to left-right asymmetry downstream or in parallel to nodal flow. Dev Dyn 2006; 235:1794-808. [PMID: 16628609 DOI: 10.1002/dvdy.20800] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
While there is a good conceptual framework of dorsoventral and anterioposterior axes formation in most vertebrate groups, understanding of left-right axis initiation is fragmentary. Diverse mechanisms have been implied to contribute to the earliest steps of left-right asymmetry, including small molecule signals, gap junctional communication, membrane potential, and directional flow of extracellular liquid generated by monocilia in the node region. Here we demonstrate that a mutation in the zebrafish Na,K-ATPase subunit atp1a1a causes left-right defects including isomerism of internal organs at the anatomical level. The normally left-sided Nodal signal spaw as well as its inhibitor lefty are expressed bilaterally, while pitx2 may appear random or bilateral. Monocilia movement and fluid circulation in Kupffer's vesicle are normal in atp1a1a(m883) mutant embryos. Therefore, the Na,K-ATPase is required downstream or in parallel to monocilia function during initiation of left-right asymmetry in zebrafish.
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Affiliation(s)
- Elin Ellertsdottir
- Developmental Biology, Institute Biology 1, University of Freiburg, Freiburg, Germany
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35
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Raya A, Izpisúa Belmonte JC. Left-right asymmetry in the vertebrate embryo: from early information to higher-level integration. Nat Rev Genet 2006; 7:283-93. [PMID: 16543932 DOI: 10.1038/nrg1830] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although vertebrates seem to be essentially bilaterally symmetrical on the exterior, there are numerous interior left-right asymmetries in the disposition and placement of internal organs. These asymmetries are established during embryogenesis by complex epigenetic and genetic cascades. Recent studies in a range of model organisms have made important progress in understanding how this laterality information is generated and conveyed to large regions of the embryo. Both commonalities and divergences are emerging in the mechanisms that different vertebrates use in left-right axis specification. Recent evidence also provides intriguing links between the establishment of left-right asymmetries and the symmetrical elongation of the anterior-posterior axis.
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Affiliation(s)
- Angel Raya
- Center of Regenerative Medicine in Barcelona and Instituci Catalana de Recerca i Estudis Avanats (ICREA), Doctor Aiguader 80, 08003 Barcelona, Spain
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36
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Simard A, Di Pietro E, Young CR, Plaza S, Ryan AK. Alterations in heart looping induced by overexpression of the tight junction protein Claudin-1 are dependent on its C-terminal cytoplasmic tail. Mech Dev 2006; 123:210-27. [PMID: 16500087 DOI: 10.1016/j.mod.2005.12.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 12/21/2005] [Accepted: 12/21/2005] [Indexed: 10/25/2022]
Abstract
In vertebrates, the positioning of the internal organs relative to the midline is asymmetric and evolutionarily conserved. A number of molecules have been shown to play critical roles in left-right patterning. Using representational difference analysis to identify genes that are differentially expressed on the left and right sides of the chick embryo, we cloned chick Claudin-1, an integral component of epithelial tight junctions. Here, we demonstrate that retroviral overexpression of Claudin-1, but not Claudin-3, on the right side of the chick embryo between HH stages 4 and 7 randomizes the direction of heart looping. This effect was not observed when Claudin-1 was overexpressed on the left side of the embryo. A small, but reproducible, induction of Nodal expression in the perinodal region on the right side of the embryo was noted in embryos that were injected with Claudin-1 retroviral particles on their right sides. However, no changes in Lefty,Pitx2 or cSnR expression were observed. In addition, Flectin expression remained higher in the left dorsal mesocardial folds of embryos with leftwardly looped hearts resulting from Claudin-1 overexpression on the right side of the embryo. We demonstrated that Claudin-1's C-terminal cytoplasmic tail is essential for this effect: mutation of a PKC phosphorylation site in the Claudin-1 C-terminal cytoplasmic domain at threonine-206 eliminates Claudin-1's ability to randomize the direction of heart looping. Taken together, our data provide evidence that appropriate expression of the tight junction protein Claudin-1 is required for normal heart looping and suggest that phosphorylation of its cytoplasmic tail is responsible for mediating this function.
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Affiliation(s)
- Annie Simard
- Departments of Pediatrics and Human Genetics, McGill University, Montréal, Que., Canada
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37
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Kieusseian A, Chagraoui J, Kerdudo C, Mangeot PE, Gage PJ, Navarro N, Izac B, Uzan G, Forget BG, Dubart-Kupperschmitt A. Expression of Pitx2 in stromal cells is required for normal hematopoiesis. Blood 2006; 107:492-500. [PMID: 16195330 PMCID: PMC1895608 DOI: 10.1182/blood-2005-02-0529] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Accepted: 07/20/2005] [Indexed: 11/20/2022] Open
Abstract
Although the expression of Pitx2, a bicoid family homeodomain transcription factor, is highly regulated during hematopoiesis, its function during this process was not documented; we thus studied hematopoiesis in Pitx2-null mice. We found that Pitx2(-/-) embryos display hypoplastic livers with reduced numbers of hematopoietic cells, but these cells had normal hematopoietic potential, as evidenced by colony-forming assays, immature progenitor cell assays, and long-term repopulation assays. Because the microenvironment is also crucial to the development of normal hematopoiesis, we established Pitx2(-/-) and Pitx2(+/+) stromas from fetal liver and studied their hematopoietic supportive capacity. We showed that the frequency of cobblestone area-forming cells was 4-fold decreased when using Pitx2(-/-) stromal cells compared with Pitx2(+/+) stromal cells, whatever the Pitx2 genotype of hematopoietic cells tested in this assay. This defect was rescued by expression of Pitx2 into Pitx2(-/-) fetal liver stromal cells, demonstrating a major and direct role of Pitx2 in the hematopoietic supportive capacity of fetal liver stroma. Finally, we showed a reduced capacity of MS5 stromal cells expressing Pitx2 RNAi to support human hematopoiesis. Altogether these data showed that Pitx2 has major functions in the hematopoietic supportive capacity of fetal liver and adult bone marrow stromal cells.
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Ramsdell AF. Left–right asymmetry and congenital cardiac defects: Getting to the heart of the matter in vertebrate left–right axis determination. Dev Biol 2005; 288:1-20. [PMID: 16289136 DOI: 10.1016/j.ydbio.2005.07.038] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 07/21/2005] [Accepted: 07/26/2005] [Indexed: 01/20/2023]
Abstract
Cellular and molecular left-right differences that are present in the mesodermal heart fields suggest that the heart is lateralized from its inception. Left-right asymmetry persists as the heart fields coalesce to form the primary heart tube, and overt, morphological asymmetry first becomes evident when the heart tube undergoes looping morphogenesis. Thereafter, chamber formation, differentiation of the inflow and outflow tracts, and position of the heart relative to the midline are additional features of heart development that exhibit left-right differences. Observations made in human clinical studies and in animal models of laterality disease suggest that all of these features of cardiac development are influenced by the embryonic left-right body axis. When errors in left-right axis determination happen, they almost always are associated with complex congenital heart malformations. The purpose of this review is to highlight what is presently known about cardiac development and upstream processes of left-right axis determination, and to consider how perturbation of the left-right body plan might ultimately result in particular types of congenital heart defects.
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Affiliation(s)
- Ann F Ramsdell
- Department of Cell and Developmental Biology and Anatomy, School of Medicine and Program in Women's Studies, College of Arts and Sciences, University of South Carolina, Columbia, SC 29208, USA.
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Raya A, Izpisua Belmonte JC. Unveiling the establishment of left-right asymmetry in the chick embryo. Mech Dev 2005; 121:1043-54. [PMID: 15296970 DOI: 10.1016/j.mod.2004.05.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2004] [Revised: 05/11/2004] [Accepted: 05/11/2004] [Indexed: 11/17/2022]
Abstract
Vertebrates display striking left-right asymmetries in the placement of internal organs, which are concealed by a seemingly bilaterally symmetric body plan. The establishment of asymmetries about the left-right axis occurs early during embryo development and requires the concerted and sequential action of several epigenetic, genetic and cellular mechanisms. Experiments in the chick embryo model have contributed crucially to our current understanding of such mechanisms and are reviewed here. Particular emphasis is given to the elucidation of a genetic network that conveys left-right information from Hensen's node to the organ primordia, characterized to a significant degree of detail in the chick embryo. We also point out a number of early and late events in the determination of left-right asymmetries that are currently poorly understood and for whose study the chick embryo model presents several advantages. We anticipate that the availability of the chick genome sequence will be combined with multidisciplinary approaches from experimental embryology, biophysics, live-cell imaging, and mathematical modeling to boost up our knowledge of left-right organ asymmetry in the near future.
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Affiliation(s)
- Angel Raya
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd., La Jolla, CA 92037, USA.
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40
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Toro R, Saadi I, Kuburas A, Nemer M, Russo AF. Cell-specific activation of the atrial natriuretic factor promoter by PITX2 and MEF2A. J Biol Chem 2004; 279:52087-94. [PMID: 15466416 DOI: 10.1074/jbc.m404802200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PITX2 homeodomain protein is mutated in patients with Axenfeld-Rieger syndrome and is involved in the development of multiple organ systems, including the heart. We have examined the interaction of PITX2 isoforms with myocyte-enhancing factor 2A (MEF2A), which is a known regulator of cardiac development. A direct interaction between PITX2a and MEF2A was demonstrated using yeast two-hybrid and GST pull-down assays. To study the functional significance of this interaction, we used the atrial natriuretic factor (ANF) promoter. Coexpression of MEF2A and PITX2a or Pitx2c resulted in a strong synergistic activation of the ANF promoter in LS8 oral epithelial cells but not in other cell lines (NIH/3T3, Chinese hamster ovary, or C2C12). The synergism was dependent on promoter context, because it required MEF2 binding sites and was not seen with two other PITX2 target promoters. DNA binding by MEF2A was required but not sufficient for synergism. Upstream activators of p38 MAP kinases, MKK3 and MKK6, increased PITX2a and Pitx2c activity to yield up to 90-fold activation of the ANF promoter in LS8 cells. Because Axenfeld-Rieger syndrome is autosomal dominant and affects development of the oral epithelium, we tested one of the known PITX2 mutants. The PITX2a-K88E mutant protein suppressed wild type PITX2a synergism with MEF2A. These results demonstrate a promoter- and cell-specific functional interaction between PITX2 and MEF2A and suggest the possibility of coordinate control by these factors in the oral epithelium.
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Affiliation(s)
- Rafael Toro
- Genetics Program, University of Iowa, Iowa City, Iowa 52242, USA
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41
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Cooke J. Developmental mechanism and evolutionary origin of vertebrate left/right asymmetries. Biol Rev Camb Philos Soc 2004; 79:377-407. [PMID: 15191229 DOI: 10.1017/s1464793103006298] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The systematically 'handed', or directionally asymmetrical way in which the major viscera are packed within the vertebrate body is known as situs. Other less obvious vertebrate lateralisations concern cognitive neural function, and include the human phenomena of hand-use preference and language-associated cognitive partitioning. An overview, rather than an exhaustive scholarly review, is given of recent advances in molecular understanding of the mechanism that ensures normal development of 'correct' situs. While the asymmetry itself and its left/right direction are clearly vertebrate-conserved characters, data available from various embryo types are compared in order to assess the likelihood that the developmental mechanism is evolutionarily conserved in its entirety. A conserved post-gastrular 'phylotypic' stage, with left- and right-specific cascades of key, orthologous gene expressions, clearly exists. It now seems probable that earlier steps, in which symmetry-breaking information is reliably transduced to trigger these cascades on the correct sides, are also conserved at depth although it remains unclear exactly how these steps operate. Earlier data indicated that the initiation of symmetry-breaking had been transformed, among the different vertebrate classes, as drastically as has the anatomy of pre-gastrular development itself, but it now seems more likely that this apparent diversity is deceptive. Ideas concerning the functional advantages to the vertebrate lifestyle of a systematically asymmetrical visceral packing arrangement, while untestable, are accepted because they form a plausible adaptationist 'just-so' story. Nevertheless, two contrasting beliefs are possible about the evolutionary origins of situs. Major recent advances in analysis of its developmental mechanism are largely due not to zoologists, comparative anatomists or evolutionary systematists, but to molecular geneticists, and these workers have generally assumed that the asymmetry is an evolutionary novelty imposed on a true bilateral symmetry, at or close to the origin of the vertebrate clade. A major purpose of this review is to advocate an alternative view, on the grounds of comparative anatomy and molecular systematics together with the comparative study of expressions of orthologous genes in different forms. This view is that situs represents a co-optation of a pre-existing, evolutionarily ancient non-bilaterality of the adult form in a vertebrate ancestor. Viewed this way, vertebrate or chordate origins are best understood as the novel imposition of an adaptively bilateral locomotory-skeletal-neural system, around a retained non-symmetrical 'visceral' animal. One component of neuro-anatomical asymmetry, the habenular/parapineal one that originates in the diencephalon, has recently been found (in teleosts) to be initiated from the same 'phylotypic' gene cascade that controls situs development. But the function of this particular diencephalic asymmetry is currently unclear. Other left-right partitionings of brain function, including the much more recently evolved, cerebral cortically located one associated with human language and hand-use, may be controlled entirely separately from situs even though their directionality has a particular relation to it in a majority of individuals. Finally, possible relationships are discussed between the vertebrate directional asymmetries and those that occur sporadically among protostome bilaterian forms. These may have very different evolutionary and molecular bases, such that there may have been constraints, in protostome evolution, upon any exploitation of left and right for complex organismic, and particularly cognitive neural function.
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Affiliation(s)
- Jonathan Cooke
- Department of Zoology and Museum of Comparative Zoology, University of Cambridge, Downing Street, Cambridge, UK.
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Haworth KE, Healy C, Morgan P, Sharpe PT. Regionalisation of early head ectoderm is regulated by endoderm and prepatterns the orofacial epithelium. Development 2004; 131:4797-806. [PMID: 15342462 DOI: 10.1242/dev.01337] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The oral epithelium becomes regionalised proximodistally early in development, and this is reflected by the spatial expression of signalling molecules such as Fgf8 and Bmp4. This regionalisation is responsible for regulating the spatial expression of genes in the underlying mesenchyme. These genes are required for the spatial patterning of bone, cartilage orofacial development and, in mammals, teeth. The mechanism and timing of this important regionalisation during head epithelium development are not known. Using lipophilic dyes to fate map the oral epithelium in chick embryos, we show that the cells that will occupy the epithelium of the distal and the proximal mandible primordium already occupy different spatial locations in the developing head ectoderm prior to the formation of the first pharyngeal arch and neural crest migration. Moreover, the ectoderm cells fated to become proximal oral epithelium express Fgf8 and this expression requires the presence of endoderm. Thus, the first fundamental patterning process in jaw morphogenesis is controlled by the early separation of specific areas of ectoderm that are regulated by ectoderm-endoderm interactions, and does not involve neural crest cells.
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Affiliation(s)
- Kim E Haworth
- Department of Craniofacial Development, Dental Institute, Kings College London, Floor 28, Guys Hospital, London Bridge, London SE1 9RT, UK
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Wang S, Yu X, Zhang T, Zhang X, Zhang Z, Chen Y. Chick Pcl2 regulates the left-right asymmetry by repressing Shh expression in Hensen's node. Development 2004; 131:4381-91. [PMID: 15294861 DOI: 10.1242/dev.01269] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Asymmetric expression of sonic hedgehog (Shh) in the left side of Hensen's node, a crucial step for specifying the left-right (LR) axis in the chick embryo, is established by the repression of Shhexpression in the right side of the node. The transcriptional regulator that mediates this repression has not been identified. We report the isolation and characterization of a novel chick Polycomblike 2 gene, chick Pcl2, which encodes a transcription repressor and displays an asymmetric expression, downstream from Activin-βB and Bmp4, in the right side of Hensen's node in the developing embryo. In vitro mapping studies define the transcription repression activity to the PHD finger domain of the chick Pcl2 protein. Repression of chick Pcl2expression in the early embryo results in randomized heart looping direction,which is accompanied by the ectopic expression of Shh in the right side of the node and Shh downstream genes in the right lateral plate mesoderm (LPM), while overexpression of chick Pcl2 represses Shh expression in the node. The repression of Shh by chick Pcl2 was also supported by studies in which chick Pcl2 was overexpressed in the developing chick limb bud and feather bud. Similarly,transgenic overexpression of chick Pcl2 in the developing mouse limb inhibits Shh expression in the ZPA. In vitro pull-down assays demonstrated a direct interaction of the chick Pcl2 PHD finger with EZH2, a component of the ESC/E(Z) repressive complex. Taken together with the fact that chick Pcl2 was found to directly repress Shh promoter activity in vitro, our results demonstrate a crucial role for chick Pcl2 in regulating LR axis patterning in the chick by silencing Shh in the right side of the node.
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Affiliation(s)
- Shusheng Wang
- Division of Developmental Biology, Department of Cell and Molecular Biology and Center for Bioenvironmental Research, Tulane University, New Orleans, LA 70118, USA
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44
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Buxton P, Davey MG, Paton IR, Morrice DR, Francis-West PH, Burt DW, Tickle C. Craniofacial development in the talpid3 chicken mutant. Differentiation 2004; 72:348-62. [PMID: 15554946 DOI: 10.1111/j.1432-0436.2004.07207006.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The talpid(3) chicken mutant has a pleiotropic phenotype including polydactyly and craniofacial abnormalities. Limb polydactyly in talpid(3) suggests a gain of Hedgehog (Hh) signaling, whereas, paradoxically, absence of midline facial structures suggests a loss of Hh function. Here we analyze the status of Shh signaling in the talpid(3) mutant head. We show that Shh expression domains are lost from the talpid(3) head--in hindbrain, midbrain, zona limitans intrathalamica, and stomodeal ectoderm--and that direct targets of Hedgehog signaling, Ptc1, Ptc2, and Gli1, are also absent even in areas associated with primary Shh expression. These data suggest that the talpid(3) mutation leads to defective activation of the Shh pathway and, furthermore, that tissue-to-tissue transduction of Shh expression in the developing head depends on Hh pathway activation. Failure to activate the Shh pathway can also explain absence of floor plate and Hnf-3beta and Netrin-1 expression in midbrain and hindbrain and absence of Fgf-8 expression in commissural plate. Other aspects of gene expression in the talpid(3) head, however, suggest misspecification, such as maintenance of floor plate-like gene expression in telencephalon. In branchial arches and lower jaw, where Shh is expressed, changes in expression of genes involved in patterning and mesodermal specification suggest both gain and loss of Hedgehog function. Thus, analysis of gene expression in talpid(3) head shows that, as in talpid(3) limb, expression of some genes is lost, while others are ectopically expressed. Unlike the limb, many head regions depend on Hh induction of a secondary domain of Shh expression, and failure of this induction in talpid(3), together with the inability to activate the Shh pathway, explain the loss-of-function head phenotype. This gene expression analysis in the talpid(3) head also confirms and extends knowledge of the importance of Shh signaling and the balance between activation and repression of Shh targets in many aspects of craniofacial morphogenesis.
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Affiliation(s)
- Paul Buxton
- Department of Craniofacial Development, GKT Dental Institute, Floor 27 Guy's Tower, Guy's Hospital, London SE1 9RT, UK
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Romeih M, Cui J, Michaille JJ, Jiang W, Zile MH. Function of RARgamma and RARalpha2 at the initiation of retinoid signaling is essential for avian embryo survival and for distinct events in cardiac morphogenesis. Dev Dyn 2003; 228:697-708. [PMID: 14648846 DOI: 10.1002/dvdy.10419] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Avian embryogenesis requires retinoid receptor activation by the vitamin A active form, retinoic acid (RA), during neurulation. We conducted loss-of-function analysis in quail embryos by nutritional deprivation of RA and by blocking generation of retinoid receptors. Here we identify a distinct role for RARalpha2 in cardiac inflow tract morphogenesis and for RARgamma in cardiac left/right orientation and looping morphogenesis. Blocking normal embryos with antisense oligonucleotides to RARalpha2 or RXRalpha diminishes GATA-4 transcripts, while blocking RARgamma or RXRalpha diminishes nodal and Pitx2 transcripts; the expression of these genes in the heart forming region resembles that of the vitamin A-deficient embryo. Blocking the function of RARgamma, RARalpha2, and RXRalpha recapitulates the complete vitamin A-deficient phenotype. RARgamma is the most potent mediator of the retinoid signal at this time of development. Our studies provide strong evidence that critical RA-requiring developmental events in the early avian embryo are regulated by means of distinct retinoid receptor signaling pathways.
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Affiliation(s)
- Mahmoud Romeih
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA
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46
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Muller JK, Prather DR, Nascone-Yoder NM. Left-right asymmetric morphogenesis in the Xenopus digestive system. Dev Dyn 2003; 228:672-82. [PMID: 14648844 DOI: 10.1002/dvdy.10415] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The morphogenetic mechanisms by which developing organs become left-right asymmetric entities are unknown. To investigate this issue, we compared the roles of the left and right sides of the Xenopus embryo during the development of anatomic asymmetries in the digestive system. Although both sides contribute equivalently to each of the individual digestive organs, during the initial looping of the primitive gut tube, the left side assumes concave topologies where the right side becomes convex. Of interest, the concave surfaces of the gut tube correlate with expression of the LR gene, Pitx2, and ectopic Pitx2 mRNA induces ectopic concavities in a localized manner. A morphometric comparison of the prospective concave and convex surfaces of the gut tube reveals striking disparities in their rate of elongation but no significant differences in cell proliferation. These results provide insight into the nature of symmetry-breaking morphogenetic events during left-right asymmetric organ development.
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Affiliation(s)
- Jennifer K Muller
- Department of Biology, Collegium of Natural Sciences, Eckerd College, St. Petersburg, Florida 33711, USA
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47
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Ganga M, Espinoza HM, Cox CJ, Morton L, Hjalt TA, Lee Y, Amendt BA. PITX2 isoform-specific regulation of atrial natriuretic factor expression: synergism and repression with Nkx2.5. J Biol Chem 2003; 278:22437-45. [PMID: 12692125 DOI: 10.1074/jbc.m210163200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PITX2 and Nkx2.5 are two of the earliest known transcriptional markers of vertebrate heart development. Pitx2-/- mice present with severe cardiac malformations and embryonic lethality, demonstrating a role for PITX2 in heart development. However, little is known about the downstream targets of PITX2 in cardiogenesis. We report here that the atrial natriuretic factor (ANF) promoter is a target of PITX2. PITX2A, PITX2B, and PITX2C isoforms differentially activate the ANF promoter. However, only PITX2C can synergistically activate the ANF promoter in the presence of Nkx2.5. We further demonstrate that the procollagen lysyl hydroxylase (PLOD1) promoter is regulated by Nkx2.5. Mechanistically, PITX2C and Nkx2.5 synergistically regulate ANF and PLOD1 expression through binding to their respective DNA elements. Surprisingly, PITX2A activation of the ANF and PLOD1 promoters is repressed by co-transfection of Nkx2.5 in the C3H10T1/2 embryonic fibroblast cell line. Pitx2a and Pitx2c are endogenously expressed in C3H10T1/2 cells, and these cells express factors that differentially regulate PITX2 isoform activities. We provide a new mechanism for the regulation of heart development by PITX2 isoforms through the regulation of ANF and PLOD1 gene expression and Nkx2.5 transcriptional activity.
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Affiliation(s)
- Mrudula Ganga
- Department of Biological Science, The University of Tulsa, Tulsa, Oklahoma 74104-3189, USA
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48
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Linask KK. Regulation of heart morphology: current molecular and cellular perspectives on the coordinated emergence of cardiac form and function. BIRTH DEFECTS RESEARCH. PART C, EMBRYO TODAY : REVIEWS 2003; 69:14-24. [PMID: 12768654 DOI: 10.1002/bdrc.10004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND During early heart development, in addition to cells being induced to differentiate into cardiomyocytes, pathways are activated that lead to cardiac morphogenesis or the development of form. METHODS Orchestration of organogenesis involves the incremental activation of regulatory pathways that lead to pivotal transition points, such as cardiac compartment delineation and looping. Each embryonic stage sets up the correct patterning of morphoregulatory molecules that will regulate the next process, until an organ is formed from the mesoderm layer after gastrulation. The current review provides an understanding of the morphoregulatory, cell adhesion and extracellular matrix-mediated, processes that coordinate development of heart form with that of function. The period reviewed encompasses the formation of a definitive cardiac compartment from the lateral plate mesoderm to the time-point in which the single, beating heart tube loops directionally to the right. Looping results in the correct spatial orientation for subsequent modeling of the four-chambered heart. Even subtle alterations in looping can form the basis upon which malformations of the inlet or the outlet regions of the heart, or both, are superimposed. RESULTS In the future, DNA microarray data sets may allow modeling the specific sequence of gene regulatory dynamics leading to these transition points to discover the regulatory "modes" that the cells adopt during heart organogenesis. The regulatory genes, however, can only specify the proteins that will be present. CONCLUSIONS To fully understand the timing and mechanisms underlying heart development, it is necessary to define the sequential synthesis, patterning, and interaction of the proteins, and of still other receptors, which eventually drive cells to organize into functioning organs.
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Affiliation(s)
- Kersti K Linask
- Department of Cell Biology, University of Medicine and Dentistry of New Jersey-SOM Stratford, NJ 08084, USA.
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Piedra ME, Ros MA. BMP signaling positively regulates Nodal expression during left right specification in the chick embryo. Development 2002; 129:3431-40. [PMID: 12091313 DOI: 10.1242/dev.129.14.3431] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Exogenous application of BMP to the lateral plate mesoderm (LPM) of chick embryos at the early somite stage had a positive effect on Nodal expression. BMP applications into the right LPM were followed by a rapid activation of Nodal, while applications into the left LPM resulted in expansion of the normal domain of Nodal expression. Conversely, blocking of BMP signaling by Noggin in the left LPM interfered with the activation of Nodal expression. These results support a positive role for endogenous BMP on Nodal expression in the LPM. We also report that BMP positively regulates the expression of Caronte, Snail and Cfc in both the left and right LPM. BMP-treated embryos had molecular impairment of the midline with downregulation of Lefty1, Brachyury and Shh but we also show that the midline defect was not sufficient to induce ectopic Nodal expression. We discuss our findings in the context of the known molecular control of the specification of left-right asymmetry.
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Affiliation(s)
- M Elisa Piedra
- Departamento de Anatomía y Biología Celular, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Spain
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Cox CJ, Espinoza HM, McWilliams B, Chappell K, Morton L, Hjalt TA, Semina EV, Amendt BA. Differential regulation of gene expression by PITX2 isoforms. J Biol Chem 2002; 277:25001-10. [PMID: 11948188 DOI: 10.1074/jbc.m201737200] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Three major PITX2 isoforms are differentially expressed in human, mice, zebrafish, chick, and frog tissues. To demonstrate differential regulation of gene expression by these isoforms we used three different promoters and three cell lines. Transient transfection of Chinese hamster ovary, HeLa, and LS-8 cell lines revealed differences in PITX2A and PITX2C activation of the PLOD1 and Dlx2 promoters, however, PITX2B is inactive. In contrast, PITX2B actives the pituitary-specific Prolactin promoter at higher levels than either PITX2A or PITX2C. Interestingly, co-transfection of either PITX2A or PITX2C with PITX2B results in a synergistic activation of the PLOD1 and Dlx2 promoters. Furthermore, PITX2 isoforms have different transcriptional activity dependent upon the cells used for transfection analysis. We have isolated a fourth PITX2 isoform (PITX2D) expressed only in humans, which acts to suppress the transcriptional activity of the other PITX2 isoforms. Electrophoretic mobility shift assays and glutathione S-transferase pull-down experiments demonstrated that all isoforms interact with PITX2D and that PITX2B forms heterodimeric complexes with PITX2A and PITX2C. Our research provides a molecular basis for differential gene regulation through the expression of PITX2 isoforms. PITX2 isoform activities are both promoter- and cell-specific, and our data reveal new mechanisms for PITX2-regulated gene expression.
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Affiliation(s)
- Carol J Cox
- Department of Biological Science, The University of Tulsa, Oklahoma 74104-3189, USA
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