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Transient Nodal Signaling in Left Precursors Coordinates Opposed Asymmetries Shaping the Heart Loop. Dev Cell 2020; 55:413-431.e6. [PMID: 33171097 DOI: 10.1016/j.devcel.2020.10.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 07/17/2020] [Accepted: 10/09/2020] [Indexed: 02/06/2023]
Abstract
The secreted factor Nodal, known as a major left determinant, is associated with severe heart defects. Yet, it has been unclear how it regulates asymmetric morphogenesis such as heart looping, which align cardiac chambers to establish the double blood circulation. Here, we report that Nodal is transiently active in precursors of the mouse heart tube poles, before looping. In conditional mutants, we show that Nodal is not required to initiate asymmetric morphogenesis. We provide evidence of a heart-specific random generator of asymmetry that is independent of Nodal. Using 3D quantifications and simulations, we demonstrate that Nodal functions as a bias of this mechanism: it is required to amplify and coordinate opposed left-right asymmetries at the heart tube poles, thus generating a robust helical shape. We identify downstream effectors of Nodal signaling, regulating asymmetries in cell proliferation, differentiation, and extracellular matrix composition. Our study uncovers how Nodal regulates asymmetric organogenesis.
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2
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Rozani I, Tsapara G, Witts EC, Deaville SJ, Miles GB, Zagoraiou L. Pitx2 cholinergic interneurons are the source of C bouton synapses on brainstem motor neurons. Sci Rep 2019; 9:4936. [PMID: 30894556 PMCID: PMC6426951 DOI: 10.1038/s41598-019-39996-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 01/15/2019] [Indexed: 11/29/2022] Open
Abstract
Cholinergic neuromodulation has been described throughout the brain and has been implicated in various functions including attention, food intake and response to stress. Cholinergic modulation is also thought to be important for regulating motor systems, as revealed by studies of large cholinergic synapses on spinal motor neurons, called C boutons, which seem to control motor neuron excitability in a task-dependent manner. C boutons on spinal motor neurons stem from spinal interneurons that express the transcription factor Pitx2. C boutons have also been identified on the motor neurons of specific cranial nuclei. However, the source and roles of cranial C boutons are less clear. Previous studies suggest that they originate from Pitx2+ and Pitx2- neurons, in contrast to spinal cord C boutons that originate solely from Pitx2 neurons. Here, we address this controversy using mouse genetics, and demonstrate that brainstem C boutons are Pitx2+ derived. We also identify new Pitx2 populations and map the cholinergic Pitx2 neurons of the mouse brain. Taken together, our data present important new information about the anatomical organization of cholinergic systems which impact motor systems of the brainstem. These findings will enable further analyses of the specific roles of cholinergic modulation in motor control.
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Affiliation(s)
- Ismini Rozani
- Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, 4 Soranou Ephessiou Str., 11527, Athens, Greece
- Division of Animal and Human Physiology, Department of Biology, National & Kapodistrian University of Athens, Panepistimiopolis, Ilisia, Greece
| | - Georgia Tsapara
- Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, 4 Soranou Ephessiou Str., 11527, Athens, Greece
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Emily C Witts
- Sainsbury Wellcome Centre, 25 Howland Street, London, W1T 4JG, UK
- School of Psychology & Neuroscience, University of St Andrews, Fife, KY169JP, UK
| | - S James Deaville
- School of Psychology & Neuroscience, University of St Andrews, Fife, KY169JP, UK
| | - Gareth B Miles
- School of Psychology & Neuroscience, University of St Andrews, Fife, KY169JP, UK
| | - Laskaro Zagoraiou
- Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, 4 Soranou Ephessiou Str., 11527, Athens, Greece.
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3
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Montenegro YHA, de Queiroga Nascimento D, de Assis TO, Santos-Lopes SSD. The epigenetics of the hypothalamic-pituitary-adrenal axis in fetal development. Ann Hum Genet 2019; 83:195-213. [PMID: 30843189 DOI: 10.1111/ahg.12306] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 02/13/2019] [Accepted: 02/14/2019] [Indexed: 01/16/2023]
Abstract
The hypothalamic-pituitary-adrenal (HPA) axis is an important hormonal mechanism of the human body and is extremely programmable during embryonic and fetal development. Analyzing its development in this period is the key to understanding in fact how vulnerabilities of congenital diseases occur and any other changes in the phenotypic and histophysiological aspects of the fetus. The environment in which the mother is exposed during the gestational period can influence this axis. Knowing this, our objective was to analyze in recent research the possible impact of epigenetic programming on the HPA axis and its consequences for fetal development. This review brought together articles from two databases: ScienceDirect and PUBMED researched based on key words such as "epigenetics, HPA axis, cardiovascular disease, and circulatory problems" where it demonstrated full relevance in experimental and scientific settings. A total of 101 articles were selected following the criteria established by the researchers. Thus, it was possible to verify that the development of the HPA axis is directly related to changes that occur in the cardiovascular system, to the cerebral growth and other systems depending on the influence that it receives in the period of fetal formation.
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4
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Ellsworth BS, Stallings CE. Molecular Mechanisms Governing Embryonic Differentiation of Pituitary Somatotropes. Trends Endocrinol Metab 2018; 29:510-523. [PMID: 29759686 DOI: 10.1016/j.tem.2018.04.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 04/18/2018] [Accepted: 04/19/2018] [Indexed: 02/07/2023]
Abstract
Pituitary somatotropes secrete growth hormone (GH), which is essential for normal growth and metabolism. Somatotrope defects result in GH deficiency (GHD), leading to short stature in childhood and increased cardiovascular morbidity and mortality in adulthood. Current hormone replacement therapies fail to recapitulate normal pulsatile GH secretion. Stem cell therapies could overcome this problem but are dependent on a thorough understanding of somatotrope differentiation. Although several transcription factors, signaling pathways, and hormones that regulate this process have been identified, the mechanisms of action are not well understood. The purpose of this review is to highlight the known players in somatotrope differentiation while emphasizing the need to better understand these pathways to serve patients with GHD.
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Affiliation(s)
- Buffy S Ellsworth
- Department of Physiology, School of Medicine, Southern Illinois University, Carbondale, IL 62901-6523, USA.
| | - Caitlin E Stallings
- Department of Physiology, School of Medicine, Southern Illinois University, Carbondale, IL 62901-6523, USA
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5
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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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6
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Hernandez-Torres F, Rodríguez-Outeiriño L, Franco D, Aranega AE. Pitx2 in Embryonic and Adult Myogenesis. Front Cell Dev Biol 2017; 5:46. [PMID: 28507987 PMCID: PMC5410577 DOI: 10.3389/fcell.2017.00046] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/12/2017] [Indexed: 12/11/2022] Open
Abstract
Skeletal muscle is a heterogeneous tissue that represents between 30 and 38% of the human body mass and has important functions in the organism, such as maintaining posture, locomotor impulse, or pulmonary ventilation. The genesis of skeletal muscle during embryonic development is a process controlled by an elaborate regulatory network combining the interplay of extrinsic and intrinsic regulatory mechanisms that transform myogenic precursor cells into functional muscle fibers through a finely tuned differentiation program. However, the capacity of generating muscle still remains once these fibers have matured. Adult myogenesis resembles many of the embryonic morphogenetic episodes and depends on the activation of satellite cells that have the potential to differentiate into new muscle fibers. Pitx2 is a member of the bicoid family of homeodomain transcription factors that play an important role in morphogenesis. In the last decade, Pitx2 has emerged as a key element involved in the fine-tuning mechanism that regulates skeletal-muscle development as well as the differentiation and cell fate of satellite cells in adult muscle. Here we present an integrative view of all aspects of embryonic and adult myogenesis in which Pitx2 is involved, from embryonic development to satellite-cell proliferation, fate specification, and differentiation. Those new Pitx2 functions on satellite-cell biology might open new perspectives to develop therapeutic strategies for muscular disorders.
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Affiliation(s)
- Francisco Hernandez-Torres
- Cardiac and Skeletal Myogenesis Group, Departmento de Biología Experimental, Universidad de JaénJaén, Spain.,Cardiac and Skeletal Myogenesis Group, Fundación MEDINA Centro de Excelencia en Investigación de Medicamentos Innovadores en AndalucíaGranada, Spain
| | - Lara Rodríguez-Outeiriño
- Cardiac and Skeletal Myogenesis Group, Departmento de Biología Experimental, Universidad de JaénJaén, Spain.,Cardiac and Skeletal Myogenesis Group, Fundación MEDINA Centro de Excelencia en Investigación de Medicamentos Innovadores en AndalucíaGranada, Spain
| | - Diego Franco
- Cardiac and Skeletal Myogenesis Group, Departmento de Biología Experimental, Universidad de JaénJaén, Spain.,Cardiac and Skeletal Myogenesis Group, Fundación MEDINA Centro de Excelencia en Investigación de Medicamentos Innovadores en AndalucíaGranada, Spain
| | - Amelia E Aranega
- Cardiac and Skeletal Myogenesis Group, Departmento de Biología Experimental, Universidad de JaénJaén, Spain.,Cardiac and Skeletal Myogenesis Group, Fundación MEDINA Centro de Excelencia en Investigación de Medicamentos Innovadores en AndalucíaGranada, Spain
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Klafke R, Prem Anand AA, Wurst W, Prakash N, Wizenmann A. Differences in the spatiotemporal expression and epistatic gene regulation of the mesodiencephalic dopaminergic precursor marker PITX3 during chicken and mouse development. Development 2016; 143:691-702. [DOI: 10.1242/dev.126748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 01/05/2016] [Indexed: 11/20/2022]
Abstract
Mesodiencephalic dopaminergic (mdDA) neurons are located in the ventral mesencephalon and caudal diencephalon of all tetrapod species studied so far. They are the most prominent DA neuronal population and are implicated in control and modulation of motor, cognitive and rewarding/affective behaviors. Their degeneration or dysfunction is intimately linked to several neurological and neuropsychiatric human diseases. To gain further insights into their generation, we studied spatiotemporal expression patterns and epistatic interactions in chick embryos of selected marker genes and signaling pathways associated with mdDA neuron development in mouse. We detected striking differences in the expression patterns of the chick orthologs of the mouse mdDA marker genes Pitx3 and Aldh1a1, which suggests important differences between the species in the generation/generating of these cells. We also discovered that the Sonic hedgehog signaling pathway is both, necessary and sufficient for the induction of ectopic PITX3 expression in chick mesencephalon downstream of WNT9A induced LMX1a transcription. These aspects of early chicken development resemble the ontogeny of zebrafish diencephalic DA neuronal populations, and suggest a divergence between birds and mammals during evolution.
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Affiliation(s)
- Ruth Klafke
- Institute of Developmental Genetics, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - A. Alwin Prem Anand
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Oesterbergstrasse 3, 72074 Tuebingen, Germany
| | - Wolfgang Wurst
- Institute of Developmental Genetics, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
- Technische Universität München-Weihenstephan, Lehrstuhl für Entwicklungsgenetik c/o Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Standort München, Schillerstr. 44, 80336 München, Germany
- Munich Cluster for Systems Neurology (SyNergy), Adolf-Butenandt-Institut, Ludwig-Maximilians-Universität München, Schillerstrasse 44, 80336 München, Germany
| | - Nilima Prakash
- Institute of Developmental Genetics, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
- Technische Universität München-Weihenstephan, Lehrstuhl für Entwicklungsgenetik c/o Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Andrea Wizenmann
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Oesterbergstrasse 3, 72074 Tuebingen, Germany
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Knopp P, Figeac N, Fortier M, Moyle L, Zammit PS. Pitx genes are redeployed in adult myogenesis where they can act to promote myogenic differentiation in muscle satellite cells. Dev Biol 2013; 377:293-304. [PMID: 23438814 DOI: 10.1016/j.ydbio.2013.02.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 01/29/2013] [Accepted: 02/15/2013] [Indexed: 11/17/2022]
Abstract
Skeletal muscle retains a resident stem cell population called satellite cells. Although mitotically quiescent in mature muscle, satellite cells can be activated to produce myoblast progeny to generate myonuclei for skeletal muscle homoeostasis, hypertrophy and repair. Regulation of satellite cell function in adult requires redeployment of many of the regulatory networks fundamental to developmental myogenesis. Involved in such control of muscle stem cell fate in embryos are members of the Pitx gene family of bicoid-class homeodomain proteins. Here, we investigated the expression and function of all three Pitx genes in muscle satellite cells of adult mice. Endogenous Pitx1 was undetectable, whilst Pitx2a, Pitx2b and Pitx2c were at low levels in proliferating satellite cells, but increased during the early stages of myogenic differentiation. By contrast, proliferating satellite cells expressed robust amounts of Pitx3, with levels then decreasing as cells differentiated, although Pitx3 remained expressed in unfused myoblasts. To examine the role of Pitx genes in satellite cell function, retroviral-mediated expression of Pitx1, all Pitx2 isoforms or Pitx3, was used. Constitutive expression of any Pitx isoform suppressed satellite cell proliferation, with the cells undergoing enhanced myogenic differentiation. Conversely, myogenic differentiation into multinucleated myotubes was decreased when Pitx2 or Pitx3 levels were reduced using siRNA. Together, our results show that Pitx genes play a role in regulating satellite cell function during myogenesis in adult.
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Affiliation(s)
- Paul Knopp
- King's College London, Randall Division of Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, London, SE1 1UL, England, UK
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9
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Zhang Z, Gutierrez D, Li X, Bidlack F, Cao H, Wang J, Andrade K, Margolis HC, Amendt BA. The LIM homeodomain transcription factor LHX6: a transcriptional repressor that interacts with pituitary homeobox 2 (PITX2) to regulate odontogenesis. J Biol Chem 2013; 288:2485-500. [PMID: 23229549 PMCID: PMC3554917 DOI: 10.1074/jbc.m112.402933] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 11/29/2012] [Indexed: 11/06/2022] Open
Abstract
LHX6 is a LIM-homeobox transcription factor expressed during embryogenesis; however, the molecular mechanisms regulating LHX6 transcriptional activities are unknown. LHX6 and the PITX2 homeodomain transcription factor have overlapping expression patterns during tooth and craniofacial development, and in this report, we demonstrate new transcriptional mechanisms for these factors. PITX2 and LHX6 are co-expressed in the oral and dental epithelium and epithelial cell lines. Lhx6 expression is increased in Pitx2c transgenic mice and decreased in Pitx2 null mice. PITX2 activates endogenous Lhx6 expression and the Lhx6 promoter, whereas LHX6 represses its promoter activity. Chromatin immunoprecipitation experiments reveal endogenous PITX2 binding to the Lhx6 promoter. LHX6 directly interacts with PITX2 to inhibit PITX2 transcriptional activities and activation of multiple promoters. Bimolecular fluorescence complementation assays reveal an LHX6·PITX2 nuclear interaction in living cells. LHX6 has a dominant repressive effect on the PITX2 synergistic activation with LEF-1 and β-catenin co-factors. Thus, LHX6 acts as a transcriptional repressor and represses the expression of several genes involved in odontogenesis. We have identified specific defects in incisor, molar, mandible, bone, and root development and late stage enamel formation in Lhx6 null mice. Amelogenin and ameloblastin expression is reduced and/or delayed in the Lhx6 null mice, potentially resulting from defects in dentin deposition and ameloblast differentiation. Our results demonstrate that LHX6 regulates cell proliferation in the cervical loop and promotes cell differentiation in the anterior region of the incisor. We demonstrate new molecular mechanisms for LHX6 and an interaction with PITX2 for normal craniofacial and tooth development.
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Affiliation(s)
- Zichao Zhang
- From the Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030 and
| | - Diana Gutierrez
- From the Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030 and
| | - Xiao Li
- From the Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030 and
| | - Felicitas Bidlack
- the Department of Biomineralization, The Forsyth Institute, Boston, Massachusetts 02142
| | - Huojun Cao
- From the Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030 and
| | - Jianbo Wang
- From the Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030 and
| | - Kelsey Andrade
- From the Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030 and
| | - Henry C. Margolis
- the Department of Biomineralization, The Forsyth Institute, Boston, Massachusetts 02142
| | - Brad A. Amendt
- From the Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A & M University Health Science Center, Houston, Texas 77030 and
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10
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Alam DA, Sala FG, Baptista S, Galzote R, Danopoulos S, Tiozzo C, Gage P, Grikscheit T, Warburton D, Frey MR, Bellusci S. FGF9-Pitx2-FGF10 signaling controls cecal formation in mice. Dev Biol 2012; 369:340-8. [PMID: 22819677 PMCID: PMC3725282 DOI: 10.1016/j.ydbio.2012.07.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 06/19/2012] [Accepted: 07/10/2012] [Indexed: 01/09/2023]
Abstract
Fibroblast growth factor (FGF) signaling to the epithelium and mesenchyme mediated by FGF10 and FGF9, respectively, controls cecal formation during embryonic development. In particular, mesenchymal FGF10 signals to the epithelium via FGFR2b to induce epithelial cecal progenitor cell proliferation. Yet the precise upstream mechanisms controlling mesenchymal FGF10 signaling are unknown. Complete deletion of Fgf9 as well as of Pitx2, a gene encoding a homeobox transcription factor, both lead to cecal agenesis. Herein, we used mouse genetic approaches to determine the precise contribution of the epithelium and/or mesenchyme tissue compartments in this process. Using tissue compartment specific Fgf9 versus Pitx2 loss of function approaches in the gut epithelium and/or mesenchyme, we determined that FGF9 signals to the mesenchyme via Pitx2 to induce mesenchymal Fgf10 expression, which in turn leads to epithelial cecal bud formation.
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MESH Headings
- Animals
- Base Sequence
- Cecum/abnormalities
- Cecum/embryology
- Cecum/metabolism
- Cell Proliferation
- DNA Primers/genetics
- Epithelial Cells/cytology
- Epithelial Cells/metabolism
- Female
- Fibroblast Growth Factor 10/deficiency
- Fibroblast Growth Factor 10/genetics
- Fibroblast Growth Factor 10/metabolism
- Fibroblast Growth Factor 9/deficiency
- Fibroblast Growth Factor 9/genetics
- Fibroblast Growth Factor 9/metabolism
- Gene Expression Regulation, Developmental
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Male
- Mesoderm/embryology
- Mesoderm/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Mutant Strains
- Mice, Transgenic
- Models, Biological
- Pregnancy
- Receptor, Fibroblast Growth Factor, Type 2/genetics
- Receptor, Fibroblast Growth Factor, Type 2/metabolism
- Signal Transduction
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Homeobox Protein PITX2
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Affiliation(s)
- Denise Al Alam
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Frederic G Sala
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Sheryl Baptista
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Rosanna Galzote
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Soula Danopoulos
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Caterina Tiozzo
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Philip Gage
- University of Michigan Kellogg Eye Center, 1000 Wall Street, Ann Arbor, MI, USA
| | - Tracy Grikscheit
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - David Warburton
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Mark R Frey
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Saverio Bellusci
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute of Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
- Excellence Cluster in Cardio-Pulmonary Systems, University of Giessen Lung Center, Department of Internal Medicine II, Klinikstrasse 36, 35392 Giessen, Germany
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11
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Skidmore JM, Waite MR, Alvarez-Bolado G, Puelles L, Martin DM. A novel TaulacZ allele reveals a requirement for Pitx2 in formation of the mammillothalamic tract. Genesis 2012; 50:67-73. [DOI: 10.1002/dvg.20793] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 08/04/2011] [Accepted: 08/19/2011] [Indexed: 12/25/2022]
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12
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Waite MR, Skaggs K, Kaviany P, Skidmore JM, Causeret F, Martin JF, Martin DM. Distinct populations of GABAergic neurons in mouse rhombomere 1 express but do not require the homeodomain transcription factor PITX2. Mol Cell Neurosci 2012; 49:32-43. [PMID: 21925604 PMCID: PMC3244529 DOI: 10.1016/j.mcn.2011.08.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 08/04/2011] [Accepted: 08/30/2011] [Indexed: 11/20/2022] Open
Abstract
Hindbrain rhombomere 1 (r1) is located caudal to the isthmus, a critical organizer region, and rostral to rhombomere 2 in the developing mouse brain. Dorsal r1 gives rise to the cerebellum, locus coeruleus, and several brainstem nuclei, whereas cells from ventral r1 contribute to the trochlear and trigeminal nuclei as well as serotonergic and GABAergic neurons of the dorsal raphe. Recent studies have identified several molecular events controlling dorsal r1 development. In contrast, very little is known about ventral r1 gene expression and the genetic mechanisms regulating its formation. Neurons with distinct neurotransmitter phenotypes have been identified in ventral r1 including GABAergic, serotonergic, and cholinergic neurons. Here we show that PITX2 marks a distinct population of GABAergic neurons in mouse embryonic ventral r1. This population appears to retain its GABAergic identity even in the absence of PITX2. We provide a comprehensive map of markers that places these PITX2-positive GABAergic neurons in a region of r1 that intersects and is potentially in communication with the dorsal raphe.
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Affiliation(s)
- Mindy R Waite
- Program in Cell and Molecular Biology, 2966 Taubman Medical Library, University of Michigan, Ann Arbor, MI 48109-0619, USA.
| | - Kaia Skaggs
- Department of Neurology, 3520A MSRB I, University of Michigan, Ann Arbor, MI, 48019-5652, USA.
| | - Parisa Kaviany
- Department of Pediatrics, 3520A MSRB I, University of Michigan, Ann Arbor, MI, 48019-5652, USA.
| | - Jennifer M Skidmore
- Department of Pediatrics, 3520A MSRB I, University of Michigan, Ann Arbor, MI, 48019-5652, USA.
| | - Frédéric Causeret
- Institut Jacques Monod, Université Paris Diderot, CNRS UMR 7592, Sorbonne Paris Cité, Paris, France.
| | - James F Martin
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Cardiomyocyte Renewal Lab Texas Heart Institute, Houston Texas, 77030, USA.
| | - Donna M Martin
- Program in Cell and Molecular Biology, 2966 Taubman Medical Library, University of Michigan, Ann Arbor, MI 48109-0619, USA; Department of Pediatrics, 3520A MSRB I, University of Michigan, Ann Arbor, MI, 48019-5652, USA; Department of Human Genetics, 3520A MSRB I, University of Michigan, Ann Arbor, MI, 48019-5652, USA.
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13
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Hirose H, Ishii H, Mimori K, Tanaka F, Takemasa I, Mizushima T, Ikeda M, Yamamoto H, Sekimoto M, Doki Y, Mori M. The significance of PITX2 overexpression in human colorectal cancer. Ann Surg Oncol 2011; 18:3005-12. [PMID: 21479692 DOI: 10.1245/s10434-011-1653-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Indexed: 01/27/2023]
Abstract
PURPOSE The paired-like homeodomain transcription factor 2 (PITX2) gene encodes a transcription factor controlled by the WNT/Dvl/CTNNB1 and Hedgehog/TGFB pathways in the pathogenesis of colorectal cancer (CRC). Although PITX2 is reportedly involved in various functions, including tissue development by controlling cell growth, its significance in CRC remains unclear. We report our findings regarding abnormal PITX2 expression in human CRC. METHODS PITX2 expression was evaluated in 5 human CRC cell lines and 92 primary CRC samples. Cell growth was evaluated after inhibition of PITX2 expression or after exogenous introduction of PITX2. RESULTS PITX2 expression was seen in all the five CRC cell lines. The study of tissue samples indicated that PITX2 expression was significantly higher in cancerous tissue than in paired control tissue (P = 0.0471). Patients with lower PITX2 expression showed a poorer overall survival rate than those with higher PITX2 expression (P = 0.0481). Multivariate analysis demonstrated that PITX2 expression was an independent prognostic factor. Experimental knockdown and introduction of PITX2 also demonstrated that the level of PITX2 expression is inversely associated with cell growth and invasion in vitro. CONCLUSIONS PITX2 expression is significantly related to the biological behavior of CRC cells and appears to be correlated with clinical survival. Thus, this study revealed a previously uncharacterized unique role and significance of PITX2 expression in CRC.
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Affiliation(s)
- Hajime Hirose
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.
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14
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Delaunay D, Heydon K, Miguez A, Schwab M, Nave KA, Thomas JL, Spassky N, Martinez S, Zalc B. Genetic tracing of subpopulation neurons in the prethalamus of mice (Mus musculus). J Comp Neurol 2009; 512:74-83. [PMID: 18973275 DOI: 10.1002/cne.21904] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Genetic labeling based on the Cre/lox reporter system has allowed the creation of fate maps for progenitor cells and their offspring. In the diencephalon, pools of progenitors express the plp transcripts in the zona limitans intrathalamica (ZLI), the basal plate of the diencephalon (bpD), and the posterior part of the hypothalamus. We used plp-Cre transgenics crossed with either Rosa26-lox-lacZ (R26R) or actin-lox gfp (Z/EG) reporter mice to investigate the progeny of plp-expressing ventricular cells in the diencephalon. We describe the subpopulations of prethalamic neurons derived from plp-activated progenitors, their possible migratory routes as development proceeds, and their final positional identity. Neurons derived from plp-expressing progenitors issued from the ZLI contribute to GABAergic cells in the zona incerta, the subgeniculate nucleus, the ventral lateral geniculate, and the intergeniculate leaflet. Plp(+) progenitors in the bpD and posterior hypothalamus appear to generate glutamatergic neurons in the subthalamic nucleus and GABAergic neurons in the mammillary and retromammillary tegmentum derivatives. In all these nuclei the contribution of plp(+) progenitors is only partial, illustrating the heterogeneity of origin of neurons in prethalamic and caudal hypothalamic nuclei.
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15
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Venugopalan SR, Amen MA, Wang J, Wong L, Cavender AC, D'Souza RN, Akerlund M, Brody SL, Hjalt TA, Amendt BA. Novel expression and transcriptional regulation of FoxJ1 during oro-facial morphogenesis. Hum Mol Genet 2008; 17:3643-54. [PMID: 18723525 PMCID: PMC2733810 DOI: 10.1093/hmg/ddn258] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 08/20/2008] [Indexed: 11/12/2022] Open
Abstract
Axenfeld-Rieger syndrome (ARS) patients with PITX2 point mutations exhibit a wide range of clinical features including mild craniofacial dysmorphism and dental anomalies. Identifying new PITX2 targets and transcriptional mechanisms are important to understand the molecular basis of these anomalies. Chromatin immunoprecipitation assays demonstrate PITX2 binding to the FoxJ1 promoter and PITX2C transgenic mouse fibroblasts and PITX2-transfected cells have increased endogenous FoxJ1 expression. FoxJ1 is expressed at embryonic day 14.5 (E14.5) in early tooth germs, then down-regulated from E15.5-E17.5 and re-expressed in the inner enamel epithelium, oral epithelium, tongue epithelium, sub-mandibular salivary gland and hair follicles during E18.5 and neonate day 1. FoxJ1 and Pitx2 exhibit overlapping expression patterns in the dental and oral epithelium. PITX2 activates the FoxJ1 promoter and, Lef-1 and beta-catenin interact with PITX2 to synergistically regulate the FoxJ1 promoter. FoxJ1 physically interacts with the PITX2 homeodomain to synergistically regulate FoxJ1, providing a positive feedback mechanism for FoxJ1 expression. Furthermore, FoxJ1, PITX2, Lef-1 and beta-catenin act in concert to activate the FoxJ1 promoter. The PITX2 T68P ARS mutant protein physically interacts with FoxJ1; however, it cannot activate the FoxJ1 promoter. These data indicate a mechanism for the activity of the ARS mutant proteins in specific cell types and provides a basis for craniofacial/ tooth anomalies observed in these patients. These data reveal novel transcriptional mechanisms of FoxJ1 and demonstrate a new role of FoxJ1 in oro-facial morphogenesis.
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Affiliation(s)
- Shankar R. Venugopalan
- Texas A&M Health Science Center, Institute of Biosciences and Technology, Houston, TX, USA
| | - Melanie A. Amen
- Texas A&M Health Science Center, Institute of Biosciences and Technology, Houston, TX, USA
| | - Jianbo Wang
- Texas A&M Health Science Center, Institute of Biosciences and Technology, Houston, TX, USA
| | - Leeyean Wong
- Texas A&M Health Science Center, Institute of Biosciences and Technology, Houston, TX, USA
| | - Adriana C. Cavender
- Texas A&M Health Science Center, Baylor College of Dentistry, Dallas, TX, USA
| | - Rena N. D'Souza
- Texas A&M Health Science Center, Baylor College of Dentistry, Dallas, TX, USA
| | - Mikael Akerlund
- Department of Experimental Medical Research, Lund University, Lund, Sweden
| | - Steve L. Brody
- Department of Internal Medicine, Washington University School of Medicine, St Louis, MO, USA
| | - Tord A. Hjalt
- Department of Experimental Medical Research, Lund University, Lund, Sweden
| | - Brad A. Amendt
- Texas A&M Health Science Center, Institute of Biosciences and Technology, Houston, TX, USA
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16
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Harbeck N, Nimmrich I, Hartmann A, Ross JS, Cufer T, Grützmann R, Kristiansen G, Paradiso A, Hartmann O, Margossian A, Martens J, Schwope I, Lukas A, Müller V, Milde-Langosch K, Nährig J, Foekens J, Maier S, Schmitt M, Lesche R. Multicenter study using paraffin-embedded tumor tissue testing PITX2 DNA methylation as a marker for outcome prediction in tamoxifen-treated, node-negative breast cancer patients. J Clin Oncol 2008; 26:5036-42. [PMID: 18711169 DOI: 10.1200/jco.2007.14.1697] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE We recently reported DNA methylation of the paired-like homeodomain transcription factor 2 (PITX2) gene to be strongly correlated with increased risk of recurrence in node-negative, hormone receptor-positive, tamoxifen-treated breast cancer patients using fresh frozen specimens. Aims of the present study were to establish determination of PITX2 methylation for routine analysis in formalin-fixed paraffin-embedded (FFPE) breast cancer tissue and to test PITX2 DNA methylation as a biomarker for outcome prediction in an independent patient cohort. PATIENTS AND METHODS Real-time polymerase chain reaction (PCR) technology was validated for FFPE tissue by comparing methylation measurements in FFPE specimens with those in fresh frozen specimens from the same tumor. The impact of PITX2 methylation on time to distant metastasis was then evaluated in FFPE specimens from hormone receptor-positive, node-negative breast cancer patients (n = 399, adjuvant tamoxifen monotherapy). RESULTS Reproducibility of the PCR assay in replicate measurements (r(s) > or = 0.95; n = 150) and concordant measurements between fresh frozen and FFPE tissues (r(s) = 0.81; n = 89) were demonstrated. In a multivariate model, PITX2 methylation added significant information (hazard ratio = 2.35; 95% CI, 1.20 to 4.60) to established prognostic factors (tumor size, grade, and age). CONCLUSION PITX2 methylation can be reliably assessed by real-time PCR technology in FFPE tissue. Together with our earlier studies, we have accumulated substantial evidence that PITX2 methylation analysis holds promise as a practical assay for routine clinical use to predict outcome in node-negative, tamoxifen-treated breast cancer, which might allow, based on future validation studies, the identification of low-risk patients who may be treated by tamoxifen alone.
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Affiliation(s)
- Nadia Harbeck
- Department of Obstetrics and Gynecology and Pathology, Technical University of Munich, Munich, Germany.
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17
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Reyes R, Martínez S, González M, Tramu G, Bello AR. Origin of adenohypophysial lobes and cells from Rathke's pouch in Swiss albino mice. Proliferation and expression of Pitx 2 and Calbindin D28K in corticotropic and somatotropic cell differentiation. Anat Histol Embryol 2008; 37:263-71. [PMID: 18215204 DOI: 10.1111/j.1439-0264.2007.00839.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A developmental study of the adenohypophysis of the mouse was carried out in response to several as yet unanswered questions about its organogenesis and differentiation. The main objectives were to establish the origin of adenohypophysial lobes and cells from the Rathke's pouch (RP) and elucidate the mechanisms of development and functional differentiation of the gland. Using diverse techniques, the morphological development, proliferation and differentiation were studied in order to delimit different proliferative regions in the RP, and provide a satisfactory explanation for the distribution of each cell type in the adult gland. Combining the proliferation and differentiation studies, corticotropic and somatotropic cells appear to mainly originate from undifferentiated precursors located within each of these proliferative regions. The involvement of transcription factor Pitx 2 and calcium-binding protein Calbindin D 28K in the differentiation of corticotropic and somatotropic cells is further clarified.
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Affiliation(s)
- R Reyes
- Cell Biology Section, School of Biology, University of La Laguna, 38206 Tenerife, Spain.
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18
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Skidmore JM, Cramer JD, Martin JF, Martin DM. Cre fate mapping reveals lineage specific defects in neuronal migration with loss of Pitx2 function in the developing mouse hypothalamus and subthalamic nucleus. Mol Cell Neurosci 2008; 37:696-707. [PMID: 18206388 PMCID: PMC2386145 DOI: 10.1016/j.mcn.2007.12.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Revised: 11/18/2007] [Accepted: 12/07/2007] [Indexed: 10/22/2022] Open
Abstract
Establishment of neuronal diversity is a central topic in developmental neurobiology. Prior studies implicated Pitx2, a paired-like homeodomain transcription factor, in mouse subthalamic nucleus neuronal development, but precise stages of neuronal differentiation affected (migration, axon outgrowth, fate specification) and underlying mechanisms were unknown. Here we report lineage tracing experiments using Pitx2(cre/+), Pitx2(cre/null), and conditional nuclear lacZ reporter mice to track embryonic Pitx2 expressing neurons. Migration of subthalamic nucleus and hypothalamic neurons was severely arrested in Pitx2(cre/null) embryos, and subclasses of subthalamic nucleus neurons identified by Lmx1b, Foxp1, and Foxp2-gene expression revealed differing sensitivities to Pitx2 dosage. Interestingly, embryonic subthalamic nucleus development was unaffected in Lmx1b null mice, suggesting that Pitx2 and Lmx1b act via independent genetic pathways. These data provide the first direct evidence for Pitx2-dependent neuronal migration in the developing hypothalamus, and demonstrate that complex transcriptional networks regulate regional specialization of distinct hypothalamic and subthalamic nucleus neurons.
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Affiliation(s)
- Jennifer M. Skidmore
- Department of Pediatrics, The University of Michigan Medical Center, Ann Arbor, Michigan, 48109
| | - John D. Cramer
- Department of Pediatrics, The University of Michigan Medical Center, Ann Arbor, Michigan, 48109
| | - James F. Martin
- Institute of Biosciences and Technology, Texas A&M System Health Science Center, Houston, TX 77030
| | - Donna M. Martin
- Department of Pediatrics, The University of Michigan Medical Center, Ann Arbor, Michigan, 48109
- Department of Human Genetics, The University of Michigan Medical Center, Ann Arbor, Michigan, 48109
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19
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Lamba P, Hjalt TA, Bernard DJ. Novel forms of Paired-like homeodomain transcription factor 2 (PITX2): generation by alternative translation initiation and mRNA splicing. BMC Mol Biol 2008; 9:31. [PMID: 18373856 PMCID: PMC2330153 DOI: 10.1186/1471-2199-9-31] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2007] [Accepted: 03/28/2008] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Members of the Paired-like homeodomain transcription factor (PITX) gene family, particularly PITX1 and PITX2, play important roles in normal development and in differentiated cell functions. Three major isoforms of PITX2 were previously reported to be produced through both alternative mRNA splicing (PITX2A and PITX2B) and alternative promoter usage (PITX2C). The proteins derived from these mRNAs contain identical homeodomain and carboxyl termini. Differences in the amino-termini of the proteins may confer functional differences in some contexts. RESULTS Here, we report the identification of two novel PITX2 isoforms. First, we demonstrate that the Pitx2c mRNA generates two protein products, PITX2Calpha and PITX2Cbeta, via alternative translation initiation. Second, we identified a novel mRNA splice variant, Pitx2b2, which uses the same 5' splice donor in intron 2 as Pitx2b (hereafter referred to as Pitx2b1), but employs an alternative 3' splice acceptor, leading to an in-frame deletion of 39 base pairs relative to Pitx2b1. Pitx2b2 mRNA is expressed in both murine and human pituitary. The data show that in a murine gonadotrope cell line and adult murine pituitary what was previously thought to be PITX2B1 is actually PITX2Cbeta, or perhaps PITX2B2. PITX2B1 is expressed at lower levels than previously thought. PITX2Cbeta and PITX2B2 activate gonadotrope-specific gene promoter-reporters similarly to known PITX2 isoforms. CONCLUSION We have identified and characterized two novel isoforms of PITX2, generated by alternative translation initiation (PITX2Cbeta) and alternative mRNA splicing (PITX2B2). These proteins show similar DNA binding and trans-activation functions as other PITX2 isoforms in vitro, though their conservation across species suggests that they may play distinct, as yet unidentified, roles in vivo.
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Affiliation(s)
- Pankaj Lamba
- Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - Tord A Hjalt
- Department of Experimental Medical Science, Lund University, BMC B12 Tornavagen 10, SE-22184, Lund, Sweden
| | - Daniel J Bernard
- Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
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20
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Holmberg J, Ingner G, Johansson C, Leander P, Hjalt TA. PITX2 gain-of-function induced defects in mouse forelimb development. BMC DEVELOPMENTAL BIOLOGY 2008; 8:25. [PMID: 18312615 PMCID: PMC2275225 DOI: 10.1186/1471-213x-8-25] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 02/29/2008] [Indexed: 11/19/2022]
Abstract
BACKGROUND Limb development and patterning originate from a complex interplay between the skeletal elements, tendons, and muscles of the limb. One of the genes involved in patterning of limb muscles is the homeobox transcription factor Pitx2 but its role in forelimb development is uncharacterized. Pitx2 is expressed in the majority of premature presumptive forelimb musculature at embryonic day 12.5 and then maintained throughout embryogenesis to adult skeletal muscle. RESULTS To further study the role of Pitx2 in forelimb development we have generated transgenic mice that exhibit a pulse of PITX2 over-expression at embryonic day 13.5 and 14.5 in the developing forelimb mesenchyme. These mice exhibit a distal misplacement of the biceps brachii insertion during embryogenesis, which twists the forelimb musculature resulting in severe skeletal malformations. The skeletal malformations have some similarities to the forearm deformities present in Leri-Weill dyschondrosteosis. CONCLUSION Taken together, the tendon, muscle, and bone anomalies further support a role of Pitx2 in forelimb development and may also shed light on the interaction between the skeletal elements and muscles of the limb during embryogenesis.
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Affiliation(s)
- Johan Holmberg
- Department of Experimental Medical Science, Division for Cell and Matrix Biology, Lund University, Lund, Sweden
| | - Gorel Ingner
- Diagnostic Radiology, Malmö University Hospital, Lund University, Malmö, Sweden
| | - Curt Johansson
- Diagnostic Radiology, Malmö University Hospital, Lund University, Malmö, Sweden
| | - Peter Leander
- Diagnostic Radiology, Malmö University Hospital, Lund University, Malmö, Sweden
| | - Tord A Hjalt
- Department of Experimental Medical Science, Division for Cell and Matrix Biology, Lund University, Lund, Sweden
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21
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Vue TY, Aaker J, Taniguchi A, Kazemzadeh C, Skidmore JM, Martin DM, Martin JF, Treier M, Nakagawa Y. Characterization of progenitor domains in the developing mouse thalamus. J Comp Neurol 2008; 505:73-91. [PMID: 17729296 DOI: 10.1002/cne.21467] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To understand the molecular basis of the specification of thalamic nuclei, we analyzed the expression patterns of various transcription factors and defined progenitor cell populations in the embryonic mouse thalamus. We show that the basic helix-loop-helix (bHLH) transcription factor Olig3 is expressed in the entire thalamic ventricular zone and the zona limitans intrathalamica (ZLI). Next, we define two distinct progenitor domains within the thalamus, which we name pTH-R and pTH-C, located caudal to the ZLI. pTH-R is immediately caudal to the ZLI and expresses Nkx2.2, Mash1, and Olig3. pTH-C is caudal to pTH-R and expresses Ngn1, Ngn2, and Olig3. Short-term lineage analysis of Olig3-, Mash1-, Ngn1-, and Ngn2-expressing progenitor cells as well as tracing the Pitx2 cell lineage suggests that pTH-C is the only major source of thalamic nuclei containing neurons that project to the cerebral cortex, whereas pTH-R and ZLI are likely to produce distinct postmitotic populations outside of the cortex-projecting part of the thalamus. To determine if pTH-C is composed of subdomains, we characterized expression of the homeodomain protein Dbx1 and the bHLH protein Olig2. We show that Dbx1 is expressed in caudodorsal-high to rostroventral-low gradient within pTH-C. Analysis of heterozygous Dbx1(nlslacZ) knockin mice demonstrated that Dbx1-expressing progenitors preferentially give rise to caudodorsal thalamic nuclei. Olig2 is expressed in an opposite gradient within pTH-C to that of Dbx1. These results establish the molecular heterogeneity within the progenitor cells of the thalamus, and suggest that such heterogeneity contributes to the specification of thalamic nuclei.
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Affiliation(s)
- Tou Yia Vue
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA
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22
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Cianfarani S. Neuroendocrine complications of central nervous system malformations. HANDBOOK OF CLINICAL NEUROLOGY 2008; 87:433-50. [PMID: 18809037 DOI: 10.1016/s0072-9752(07)87023-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Affiliation(s)
- Stefano Cianfarani
- Rina Balducci Center of Pediatric Endocrinology, Department of Public Health and Cell Biology, Tor Vergata University of Rome, Via Montpellier I, Rome, Italy.
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23
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Maier S, Nimmrich I, Koenig T, Eppenberger-Castori S, Bohlmann I, Paradiso A, Spyratos F, Thomssen C, Mueller V, Nährig J, Schittulli F, Kates R, Lesche R, Schwope I, Kluth A, Marx A, Martens JWM, Foekens JA, Schmitt M, Harbeck N. DNA-methylation of the homeodomain transcription factor PITX2 reliably predicts risk of distant disease recurrence in tamoxifen-treated, node-negative breast cancer patients--Technical and clinical validation in a multi-centre setting in collaboration with the European Organisation for Research and Treatment of Cancer (EORTC) PathoBiology group. Eur J Cancer 2007; 43:1679-86. [PMID: 17601725 DOI: 10.1016/j.ejca.2007.04.025] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 04/27/2007] [Indexed: 12/11/2022]
Abstract
Our aim was to identify and validate DNA-methylation markers associated with very good outcome in node negative, hormone receptor positive breast cancer patients after adjuvant endocrine therapy which might allow identifying patients who could be spared the burden of adjuvant chemotherapy. Using a methylation microarray, we analysed 117 candidate genes in hormone receptor-positive tumours from 109 breast cancer patients treated by adjuvant tamoxifen. Results were validated in an independent cohort (n=236, 5 centres). Independent methodological validation was achieved by a real-time polymerase chain reaction (PCR)-based technique. DNA methylation of PITX2 showed the strongest correlation with distant recurrence. Its impact on patient outcome was validated in the independent cohort: 86% of patients with low PITX2 methylation were metastasis-free after 10 years, compared to 69% with elevated PITX2 methylation. Moreover, PITX2 methylation added significant independent information to established clinical factors. All clinical and technical findings were confirmed by quantitative DNA-methylation PCR. These results provide strong evidence that DNA-methylation analysis allows clinically relevant risk assessment in tamoxifen-treated primary breast cancer. Based on PITX2 methylation, about half of hormone receptor-positive, node-negative breast cancer patients receiving adjuvant tamoxifen monotherapy can be considered low-risk regarding development of distant recurrences and may thus be spared adjuvant chemotherapy. In addition, these low-risk postmenopausal patients seem to respond sufficiently well to tamoxifen so that they may not require up-front aromatase inhibitor therapy.
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Affiliation(s)
- Sabine Maier
- Department of Research, Epigenomics AG, Berlin, Germany
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24
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Martínez-Fernandez S, Hernández-Torres F, Franco D, Lyons GE, Navarro F, Aránega AE. Pitx2c overexpression promotes cell proliferation and arrests differentiation in myoblasts. Dev Dyn 2006; 235:2930-9. [PMID: 16958127 DOI: 10.1002/dvdy.20924] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Pitx2 is a paired-related homeobox gene that has been shown to play a central role during development. In the mouse, there are three isoforms, Pitx2a, b, and c, which differ only in their amino terminal regions. Pitx2 is expressed in myotomes, myoblasts, and myofibers and may be involved in muscle patterning. However, the mechanism by which Pitx2 acts in muscle cell lineages as well as the distinct functions of the individual isoforms have not been investigated. In this study, we used Sol8 myoblasts to investigate the function of Pitx2 in skeletal myogenesis. We found that Pitx2c is the main Pitx2 isoform present in Sol8 myoblasts. Overexpression of Pitx2c in Sol8 myoblasts inhibited myocyte differentiation and myotube formation. Furthermore, Sol8 cells overexpressing Pitx2c maintained high proliferative capacity and a significant up-regulation of the cell cycle genes cyclin D1, cyclin D2, and c-myc. Gene expression analysis for Pax3 and the s MyoD and myogenin showed that Pitx2c-overexpression caused Sol8 cells to remain as myoblasts, in an undifferentiated myogenic state. Furthermore, down-regulation of the muscle-specific genes sTnI and MyHC3 demonstrated that Sol8-overexpressing Pitx2c myoblasts failed to reach terminal differentiation. This study sheds light on previously unknown functions of the Pitx2c isoform in balancing proliferation vs. differentiation in a myogenic cell line.
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25
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Sclafani AM, Skidmore JM, Ramaprakash H, Trumpp A, Gage PJ, Martin DM. Nestin-Cre mediated deletion of Pitx2 in the mouse. Genesis 2006; 44:336-44. [PMID: 16823861 DOI: 10.1002/dvg.20220] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Nestin-Cre mice are widely used to generate gene deletions in the developing brain. Surprisingly, fewNestin-Cre lines have been characterized for their temporal and brain region-specific recombination. In addition, some Nestin-Cre lines express Cre outside the central nervous system, making it difficult to choose appropriate lines for targeting genes with brain region-restricted expression. Here we describe the properties of a Nestin-Cre transgenic line and its use for conditional deletions of Pitx2, a paired-like homeodomain transcription factor. We report that Nestin-Cre conditional Pitx2 mutant mice have ocular and craniofacial defects consistent with the role of human PITX2 in Rieger syndrome. Conditional mutants exhibit defects in midbrain neuronal development similar to those in Pitx2 homozygous null embryos, but lack the abnormalities in subthalamic nucleus neurons that occur with complete loss of Pitx2 function. These data indicate that normal differentiation of midbrain neurons depends upon adequate Pitx2 function during the period of active neurogenesis.
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Affiliation(s)
- Anthony M Sclafani
- Molecular, Cellular and Developmental Biology Graduate Program, Yale College of Medicine, New Haven, Connecticut, USA
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26
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Acampora D, Annino A, Tuorto F, Puelles E, Lucchesi W, Papalia A, Simeone A. Otx genes in the evolution of the vertebrate brain. Brain Res Bull 2005; 66:410-20. [PMID: 16144623 DOI: 10.1016/j.brainresbull.2005.02.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Indexed: 12/01/2022]
Abstract
Only until a decade ago, animal phylogeny was traditionally based on the assumption that evolution of bilaterians went from simple to complex through gradual steps in which the extant species would represent grades of intermediate complexity that reflect the organizational levels of their ancestors. The advent of more sophisticated molecular biology techniques combined to an increasing variety of functional experiments has provided new tools, which lead us to consider evolutionary studies under a brand new light. An ancestral versus derived low-complexity of a given organism has now to be carefully re-assessed and also the molecular data so far accumulated needs to be re-evaluated. Conserved gene families expressed in the nervous system of all the species have been extensively used to reconstruct evolutionary steps, which may lead to identify the morphological as well as molecular features of the last common ancestor of bilaterians (Urbilateria). The Otx gene family is among these and will be here reviewed.
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Affiliation(s)
- Dario Acampora
- MRC Centre for Developmental Neurobiology, New Hunt's House, 4th Floor, King's College London, UK
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27
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Charles MA, Suh H, Hjalt TA, Drouin J, Camper SA, Gage PJ. PITX genes are required for cell survival and Lhx3 activation. Mol Endocrinol 2005; 19:1893-903. [PMID: 15761027 DOI: 10.1210/me.2005-0052] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The PITX family of transcription factors regulate the development of many organs. Pitx1 mutants have a mild pituitary phenotype, but Pitx2 is necessary for the development of Rathke's pouch, expression of essential transcription factors in gonadotropes, and expansion of the Pit1 lineage. We report that lack of Pitx2 causes the pouch to undergo excessive cell death, resulting in severe pituitary hypoplasia. Transgenic overexpression of PITX2 in the pituitary can increase the gonadotrope population, suggesting that the absolute concentration of PITX2 is important for normal pituitary cell lineage expansion. We show that PITX1 and PITX2 proteins are present in similar expression patterns throughout pituitary development and in the mature pituitary. Both transcription factors are preferentially expressed in adult gonadotropes and thyrotropes, suggesting the possibility of overlap in maintenance of adult pituitary functions within these cell types. Double knockouts of Pitx1 and Pitx2 exhibit severe pituitary hypoplasia and fail to express the transcription factor LHX3. This indicates that these PITX genes are upstream of Lhx3 and have compensatory roles during development. Thus, the combined dosage of these PITX family members is vital for pituitary development, and their persistent coexpression in the adult pituitary suggests a continued role in maintenance of pituitary function.
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Affiliation(s)
- Michael A Charles
- 4301 MSRB III, 1500 West Medical Center Drive, University of Michigan Medical School, Ann Arbor, MI 48109-0638, USA
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Philips ST, Albin RL, Martin DM. Genetics of subthalamic nucleus in development and disease. Exp Neurol 2005; 192:320-30. [PMID: 15755549 DOI: 10.1016/j.expneurol.2004.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Revised: 11/05/2004] [Accepted: 11/09/2004] [Indexed: 11/16/2022]
Abstract
The subthalamic nucleus (STN) is a crucial node in the basal ganglia. Clinical success in targeting the STN for deep brain stimulation in Parkinson's disease patients has prompted increased interest in understanding STN biology. In this report, we discuss recent evidence for transcription factor mediated regulation of STN development. We also review STN developmental neurobiology and known patterns of gene expression in the developing and mature STN.
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Affiliation(s)
- Steven T Philips
- Department of Pediatrics, The University of Michigan, Ann Arbor, MI 48109, USA
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Gimeno L, Corradi A, Cobos I, Consalez GG, Martinez S. Ezrin gene, coding for a membrane-cytoskeleton linker protein, is regionally expressed in the developing mouse neuroepithelium. Gene Expr Patterns 2004; 4:749-54. [PMID: 15465499 DOI: 10.1016/j.modgep.2004.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Revised: 03/08/2004] [Accepted: 03/09/2004] [Indexed: 12/20/2022]
Abstract
Ezrin is a member of the Ezrin, Radixin, Moesin (ERM) proteins family that are proposed to act as linkers between the cytoskeleton and plasma membrane. Ezrin regulates cell-cell and cell-matrix interactions playing a role in the regulation of cellular adhesion, movement and morphology in epithelia. Alterations in the expression of Ezrin and other members of ERM family have also been observed in brain tumours. Here we report the expression pattern of Ezrin during mouse neural development, from early stages to postnatal stages. In young and middle gestation embryos, Ezrin is expressed in the roof plate of the neural tube, in the presumptive domain of the choroidal plexus, and in some precise domains of ventricular epithelium. These domains are distributed in basal and alar neuroepithelial regions, some of them in relation to the expression of cadherins. At later gestation and postnatal stages, Ezrin expression is maintained on the mature choroidal plexus and is weakly detected in the proliferative regions of the mature brain.
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Affiliation(s)
- L Gimeno
- Instituto de Neurociencias, CSIC-UMH, Campus de San Juan, Apdo correos 18, 03550 Alicante, Spain
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Korotkova TM, Ponomarenko AA, Brown RE, Haas HL. Functional diversity of ventral midbrain dopamine and GABAergic neurons. Mol Neurobiol 2004; 29:243-59. [PMID: 15181237 DOI: 10.1385/mn:29:3:243] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Accepted: 11/14/2003] [Indexed: 12/21/2022]
Abstract
Recent findings indicate that VTA and SN dopaminergic (DA) and GABAergic neurons form subpopulations that are divergent in their electrophysiological features, vulnerability to neurodegeneration, and regulation by neuropeptides. This diversity can be correlated with the anatomical organization of the VTA and SN and their inputs and outputs. In this review we describe the heterogeneity in ion channels and firing patterns, especially burst firing, in subpopulations of dopamine neurons. We go on to describe variations in vulnerability to neurotoxic damage in models of Parkinson's disease in subgroups of DA neurons and its possible relationship to developmental gene regulation, the expression of different ion channels, and the expression of different protein markers, such as the neuroprotective marker calbindin. The electrophysiological properties of subgroups of GABAergic midbrain neurons, patterns of expression of protein markers and receptors, possible involvement of GABAergic neurons in a number of processes that are usually attributed exclusively to dopaminergic neurons, and the characteristics of a subgroup of neurons that contains both dopamine and GABA are also discussed.
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Affiliation(s)
- Tatiana M Korotkova
- Institute of Neurophysiology, Heinrich Heine University, D-40001 Duesseldorf, Germany.
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Moreau A, Wang DS, Forget S, Azeddine B, Angeloni D, Fraschini F, Labelle H, Poitras B, Rivard CH, Grimard G. Melatonin signaling dysfunction in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2004; 29:1772-81. [PMID: 15303021 DOI: 10.1097/01.brs.0000134567.52303.1a] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN In vitro assays were performed with bone-forming cells isolated from 41 patients with adolescent idiopathic scoliosis and 17 control patients exhibiting another type of scoliosis or none. OBJECTIVE To determine whether a dysfunction of the melatonin-signaling pathway in tissues targeted by this hormone is involved in adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA Pinealectomy in chicken has led to the formation of a scoliotic deformity, thereby suggesting that a melatonin deficiency may be at the source of adolescent idiopathic scoliosis. However, the relevance of melatonin in the etiopathogenesis of that condition is controversial because most studies have reported no significant change in circulating levels of melatonin in patients with adolescent idiopathic scoliosis. METHODS Primary osteoblast cultures prepared from bone specimens obtained intraoperatively during spine surgeries were used to test the ability of melatonin and Gpp(NH)p, a GTP analogue, to block cAMP accumulation induced by forskolin. In parallel, melatonin receptor and Gi protein functions were evaluated by immunohistochemistry and by coimmunoprecipitation experiments. RESULTS The cAMP assays demonstrated that melatonin signaling was impaired in osteoblasts isolated from adolescent idiopathic scoliosis patients to different degrees allowing their classification in 3 distinct groups based on their responsiveness to melatonin or Gpp(NH)p. CONCLUSION Melatonin signaling is clearly impaired in osteoblasts of all patients with adolescent idiopathic scoliosis tested. Classification of patients with adolescent idiopathic scoliosis in 3 groups based on functional in vitro assays suggests the presence of distinct mutations interfering with the melatonin signal transduction. Posttranslational modifications affecting Gi protein function, such as serine residues phosphorylation, should be considered as one possible mechanism in the etiopathogenesis of AIS.
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Affiliation(s)
- Alain Moreau
- Research Center, Sainte-Justine Hospital, Bone Molecular Genetics and Musculoskeletal Malformations Laboratory, Montreal, Quebec, Canada.
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Garcia-Lopez R, Vieira C, Echevarria D, Martinez S. Fate map of the diencephalon and the zona limitans at the 10-somites stage in chick embryos. Dev Biol 2004; 268:514-30. [PMID: 15063186 DOI: 10.1016/j.ydbio.2003.12.038] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2003] [Revised: 12/15/2003] [Accepted: 12/31/2003] [Indexed: 11/20/2022]
Abstract
The diencephalon is a central area of the vertebrate developing brain, where the thalamic nuclear complex, the pretectum and the anterior tegmental structures are generated. It has been subdivided into prosomeres, which are transversal domains defined by morphological and molecular criteria. The zona limitans intrathalamica is a central boundary in the diencephalon that separates the posterior diencephalon (prosomeres 1 and 2), from the anterior diencephalon (prosomere 3). This intrathalamic limit appears early on in neural tube development, and the molecular pattern that it reveals suggests an important role in the diencephalic histogenesis. We hereby present a fate map of the presumptive territories in the diencephalon of a chick embryo at the 10-11 somite stages (HH9-10), by homotopic and isochronic quail-chick grafts. The anatomical interpretation of chimeric brains was aided by correlative whole-mount in situ hybridization with RNA probes for chicken genes expressed in specific diencephalic territories. The resulting fate map describes the distribution of the presumptive diencephalic prosomeres in the neural tube, and demonstrates their topologically conserved relationships throughout the neural development. Moreover, we show that the presumptive epithelium of ZLI can be localized at early developmental stages in the diencephalic alar plate at the anterior limit of the Wnt8b gene expression domain.
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Affiliation(s)
- Raquel Garcia-Lopez
- Instituto de Neurociencias, UMH-CSIC, Universidad Miguel Hernandez, Alicante, Spain
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Martin DM, Skidmore JM, Philips ST, Vieira C, Gage PJ, Condie BG, Raphael Y, Martinez S, Camper SA. PITX2 is required for normal development of neurons in the mouse subthalamic nucleus and midbrain. Dev Biol 2004; 267:93-108. [PMID: 14975719 DOI: 10.1016/j.ydbio.2003.10.035] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 09/23/2003] [Accepted: 10/27/2003] [Indexed: 11/25/2022]
Abstract
Pitx2, a homeodomain transcription factor, is essential for normal development of the pituitary gland, craniofacial region, eyes, heart, abdominal viscera, and limbs. Complete loss of Pitx2 in mice (Pitx2(-/-)) results in embryonic lethality by approximately e15 due to cardiac defects, whereas embryos with partial loss of function (Pitx2(neo/-) or Pitx2(neo/neo)) survive until later in development (e17-e19). Pitx2 is expressed in discrete populations of postmitotic neurons in the mouse brain, but its role in mammalian central nervous system (CNS) development is not known. We undertook an analysis of Pitx2-deficient embryos to determine whether loss of Pitx2 affects CNS development. The CNS is normal in hypomorphic e16.5 Pitx2(neo/-) and e18.5 Pitx2(neo/neo) embryos, with no evidence of midline or other defects. Midgestation (e10.5) Pitx2(-/-) embryos have normally formed neural tube structures and cerebral vesicles, whereas older (e14.5) Pitx2(-/-) embryos exhibit loss of gene expression and axonal projections in the subthalamic nucleus (a group of cells in the ventrolateral thalamus) and in the developing superior colliculus of dorsal midbrain. Our results suggest a role for Pitx2 in regulating regionally specific terminal neuronal differentiation in the developing ventrolateral thalamus and midbrain.
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Affiliation(s)
- Donna M Martin
- Department of Pediatrics and Communicable Diseases, The University of Michigan, Ann Arbor, MI 48109, USA.
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Abstract
The prosomeric model attributes morphological meaning to gene expression patterns and other data in the forebrain. It divides this territory into the same transverse segments (prosomeres) and longitudinal zones in all vertebrates. The axis and longitudinal zones of this model are widely accepted but controversy subsists about the number of prosomeres and their nature as segments. We describe difficulties encountered in establishing continuity between prosomeric limits postulated in the hypothalamus and intra-telencephalic limits. Such difficulties throw doubt on the intersegmental nature of these limits. We sketch a simplified model, in which the secondary prosencephalon (telencephalon plus hypothalamus) is a complex protosegment not subdivided into prosomeres, which exhibits patterning singularities. By contrast, we continue to postulate that prosomeres p1-p3 (i.e. the pretectum, thalamus and prethalamus) are the caudal forebrain.
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Affiliation(s)
- Luis Puelles
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia 30100, Spain.
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Schausi D, Tiffoche C, Thieulant ML. Regulation of the intronic promoter of rat estrogen receptor alpha gene, responsible for truncated estrogen receptor product-1 expression. Endocrinology 2003; 144:2845-55. [PMID: 12810539 DOI: 10.1210/en.2003-0024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have characterized the intronic promoter of the rat estrogen receptor (ER) alpha gene, responsible for the lactotrope-specific truncated ER product (TERP)-1 isoform expression. Transcriptional regulation was investigated by transient transfections using 5'-deletion constructs. TERP promoter constructs were highly active in MMQ cells, a pure lactotrope cell line, whereas a low basal activity was detected in alphaT3-1 gonadotrope cells or in COS-7 monkey kidney cells. Serial deletion analysis revealed that 1) a minimal -693-bp region encompassing the TATA box is sufficient to allow lactotrope-specific expression; 2) the promoter contains strong positive cis-acting elements both in the distal and proximal regions, and 3) the region spanning the -1698/-1194 region includes repressor elements. Transient transfection studies, EMSAs, and gel shifts demonstrated that estrogen activates the TERP promoter via an estrogen-responsive element (ERE1) located within the proximal region. Mutation of ERE1 site completely abolishes the estradiol-dependent transcription, indicating that ERE1 site is sufficient to confer estrogen responsiveness to TERP promoter. In addition, ERalpha action was synergized by transfection of the pituitary-specific factor Pit-1. EMSAs showed that a single Pit-1 DNA binding element in the vicinity of the TATA box is sufficient to confer response by the TERP promoter. In conclusion, we demonstrated, for the first time, that TERP promoter regulation involves ERE and Pit-1 cis-elements and corresponding trans-acting factors, which could play a role in the physiological changes that occur in TERP-1 transcription in lactotrope cells.
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Affiliation(s)
- Diane Schausi
- Université de Rennes I, Interactions Cellulaires et Moléculaires, Equipe Information et Programmation Cellulaires, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6026, Campus de Beaulieu, 35042 Rennes Cedex, France
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36
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Kamnasaran D, O'Brien PC, Zackai EH, Muenke M, Ferguson-Smith MA, Cox DW. Rearrangement in the PITX2 and MIPOL1 genes in a patient with a t(4;14) chromosome. Eur J Hum Genet 2003; 11:315-24. [PMID: 12700605 DOI: 10.1038/sj.ejhg.5200963] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We report the molecular characterization of a patient with mild craniofacial and acallosal central nervous system midline defects and a t(4;14)(q25)(q13) chromosome. With the use of flow sorted chromosomes, the translocation breakpoint junction was defined within a 100 kb region with markers mapping to chromosomes 4q25 and 14q13. Analysis of genomic sequences demonstrated that the breakpoint junction at 14q13 was within the third intron of the 5' untranslated region of the MIPOL1 gene (GI: 22048098). On chromosome 4q25, two breakpoint junctions were found. One was about 47 kb distal to the 5' end of a putative gene (GI: 8923996) with unknown function but with partial similarity to kinases, and a second breakpoint was within the 3' end of the PITX2 gene (GI: 21361182) that resulted in the deletion of exons 6 and 7 of this gene. We also searched for microdeletions in a panel of candidate genes mapping within 2 Mb of the translocation breakpoint junction on chromosomes 4 and 14, however, no evidence for deletions or rearrangements was found. The finding of two breaks on chromosome 4q25 suggests a complex microrearrangement, such as an inversion, in addition to a translocation in this patient.
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Affiliation(s)
- Deepak Kamnasaran
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Marcil A, Dumontier E, Chamberland M, Camper SA, Drouin J. Pitx1 and Pitx2 are required for development of hindlimb buds. Development 2003; 130:45-55. [PMID: 12441290 DOI: 10.1242/dev.00192] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Two closely related homeobox transcription factors, Pitx1 and Pitx2, have been implicated in patterning of lateral plate mesoderm derivatives: Pitx1 for specification of hindlimb identity and Pitx2 for determination of laterality. We show that, together, Pitx1 and Pitx2 are required for formation of hindlimb buds and, when present in limited doses, for development of proximal (femur) and anterior (tibia and digit 1) hindlimb structures. Although Pitx1 is expressed throughout developing hindlimb buds, Pitx2 is not expressed in limb bud mesenchyme itself, but is co-expressed with Pitx1 in the presumptive hindlimb field before bud growth. Thus, Pitx1 and Pitx2 genes are required for sustained hindlimb bud growth and formation of hindlimbs.
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Affiliation(s)
- Alexandre Marcil
- Laboratoire de génétique moléculaire, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
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Martin DM, Skidmore JM, Fox SE, Gage PJ, Camper SA. Pitx2 distinguishes subtypes of terminally differentiated neurons in the developing mouse neuroepithelium. Dev Biol 2002; 252:84-99. [PMID: 12453462 DOI: 10.1006/dbio.2002.0835] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pitx2, a homeodomain transcription factor, is essential for normal development of pituitary, eyes, heart, and teeth. In the developing mouse brain, Pitx2 (Rieg, Ptx2, Otlx2, Brx1) mRNA is expressed in discrete regions of the diencephalon, mesencephalon, and rhombencephalon. While prior reports have provided an overview of the temporal and regional specificity of Pitx2 mRNA expression in the brain, the precise cell types that express PITX2 are not known. In this study, we analyzed Pitx2 mRNA and PITX2 protein expression in individual cells of the developing e10.5-e14.5 mouse CNS using multiple markers of cellular proliferation and differentiation. We identified Pitx2 expression in nestin-positive neural progenitors and in postmitotic, developing neurons. In the diencephalon, PITX2 is expressed in neurons of the zona limitans intrathalamica and mammillary region and in gamma-aminobutyric acid (GABA)-producing neurons of the zona incerta. In the mesencephalon, PITX2-labeled nuclei also appear in differentiated neurons, some of which are GABAergic and destined to occupy superior colliculus. Our results suggest that PITX2 expression in postmitotic neurons may contribute to development of GABAergic and other differentiated neuronal phenotypes.
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Affiliation(s)
- Donna M Martin
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, 48109, USA.
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Affiliation(s)
- Laurie E Cohen
- Division of Endocrinology, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
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Abstract
Pituitary gland commitment from oral ectoderm occurs in response to inductive signals from the neuroepithelium of the ventral diencephalon. Invagination of the oral ectoderm leads to the creation of Rathke's pouch. Intensified cell proliferation within Rathke's pouch results in formation of the anterior pituitary lobe. Subsequently, highly differentiated cell types arise sequentially due to overlapping, but distinct, spatial and temporal patterns of signaling molecules and transcription factors. Mutations in some of the pituitary-specific transcription factors have been identified in patients with hypopituitarism, confirming the role of these factors in pituitary development.
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Affiliation(s)
- Laurie E Cohen
- Division of Endocrinology, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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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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Conserved function of Caenorhabditis elegans UNC-30 and mouse Pitx2 in controlling GABAergic neuron differentiation. J Neurosci 2001. [PMID: 11517269 DOI: 10.1523/jneurosci.21-17-06810.2001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We are taking a cross-species approach to identify genes that are required for mammalian GABAergic neuron differentiation. On the basis of homeodomain similarity, the vertebrate Pitx genes appear to be orthologs of unc-30, a Caenorhabditis elegans gene necessary for differentiation of the GABAergic phenotype of type D neurons. One of the Pitx genes, Pitx2, is expressed in regions of GABAergic neurogenesis in the mammalian brain. These observations led us to test the functional conservation of the mouse Pitx2 and worm unc-30 genes using a rescue assay. Pitx2 rescues the GABAergic differentiation defect and partially rescues the axon guidance and behavioral phenotypes of unc-30 mutants, indicating a high degree of functional conservation between these evolutionarily related genes. Previous studies show that UNC-30 directly regulates the unc-25/glutamate decarboxylase gene that encodes the enzyme for GABA synthesis. We find that the promoter regions of the mouse and human genes coding for the 67 kDa glutamate decarboxylase (Gad1) also contain binding sites matching the UNC-30/Pitx2 consensus binding site sequence. We show that these sites specifically bind to Pitx2 protein in vitro and that in transfected neuroblastoma cells, the Pitx2 binding sites contribute to the basal activity of the Gad1 promoter. Furthermore, in cotransfection experiments, we find that Pitx2 strongly activates the Gad1 promoter. These results indicate that Pitx2 may regulate Gad1 expression in mammals, suggesting a new role for this key developmental transcription factor as a regulator of GABAergic differentiation during mammalian neural development. Our results suggest that some of the mechanisms regulating GABAergic differentiation are evolutionarily conserved.
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Degar BA, Baskaran N, Hulspas R, Quesenberry PJ, Weissman SM, Forget BG. The homeodomain gene Pitx2 is expressed in primitive hematopoietic stem/progenitor cells but not in their differentiated progeny. Exp Hematol 2001; 29:894-902. [PMID: 11438212 DOI: 10.1016/s0301-472x(01)00661-0] [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: 11/22/2022]
Abstract
OBJECTIVE Hematopoietic stem cells (HSCs) represent a rare and incompletely characterized fraction of marrow cells that are capable of both self-renewal and differentiation into all of the mature cells in the peripheral blood. We undertook to identify genes expressed preferentially by HSCs as an initial step toward better understanding the molecular mechanisms that underlie HSC behavior. METHODS We modified the representational difference analysis technique to isolate gene fragments present in amplified cDNA prepared from highly purified murine hematopoietic stem/progenitor cells (Lin(-)/Hoechst(low)/rhodamine(low)) and absent (or much less abundant) in amplified cDNA prepared from lineage-committed marrow cells. We went on to use one potentially important gene fragment that we isolated in this way, to screen a cDNA library prepared from these cells and to characterize the pattern of expression of the gene in hematopoietic and other cells. RESULTS We isolated a fragment of the homeobox transcription factor Pitx2 from amplified cDNA prepared from murine hematopoietic stem/progenitor cells. From a cDNA library prepared from these cells, a full-length cDNA was isolated that corresponds to one of the three known isoforms of Pitx2 (Pitx2c). Pitx2c is expressed in murine embryonic stem (ES) cells and in hematopoietic stem/progenitor cells but not in more differentiated hematopoietic cells or in a large panel of established murine hematopoietic cell lines. Pitx2c expression was not detected after 48 hours of in vitro cytokine stimulation of hematopoietic stem/progenitor cells. CONCLUSIONS Pitx2c is expressed in hematopoietic stem/progenitor cells but not in their differentiated progeny. The pattern of expression of Pitx2c in primitive hematopoietic stem/progenitor cells suggests that it may play a role in hematopoietic stem-cell biology.
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Affiliation(s)
- B A Degar
- Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06520-8021, USA.
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Abstract
Most of the gene candidates for the control of developmental programmes that underlie brain morphogenesis in vertebrates are the homologues of Drosophila genes coding for signalling molecules or transcription factors. Among these, the orthodenticle group includes the Drosophila orthodenticle (otd) and the vertebrate Otx1 and Otx2 genes, which are mostly involved in fundamental processes of anterior neural patterning. These genes encode transcription factors that recognise specific target sequences through the DNA binding properties of the homeodomain. In Drosophila, mutations of otd cause the loss of the anteriormost head neuromere where the gene is transcribed, suggesting that it may act as a segmentation "gap" gene. In mouse embryos, the expression patterns of Otx1 and Otx2 have shown a remarkable similarity with the Drosophila counterpart. This suggested that they could be part of a conserved control system operating in the brain and different from that coded by the HOX complexes controlling the hindbrain and spinal cord. To verify this hypothesis a series of mouse models have been generated in which the functions of the murine genes were: (i) fully inactivated, (ii) replaced with each others, (iii) replaced with the Drosophila otd gene. Otx1-/- mutants suffer from epilepsy and are affected by neurological, hormonal, and sense organ defects. Otx2-/- mice are embryonically lethal, they show gastrulation impairments and fail in specifying anterior neural plate. Analysis of the Otx1-/-; Otx2+/- double mutants has shown that a minimal threshold level of the proteins they encode is required for the correct positioning of the midbrain-hindbrain boundary (MHB). In vivo otd/Otx reciprocal gene replacement experiments have provided evidence of a general functional equivalence among otd, Otx1 and Otx2 in fly and mouse. Altogether these data highlight a crucial role for the Otx genes in specification, regionalization and terminal differentiation of rostral central nervous system (CNS) and lead to hypothesize that modification of their regulatory control may have influenced morphogenesis and evolution of the brain.
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Affiliation(s)
- D Acampora
- International Institute of Genetics and Biophysics, CNR, Via G. Marconi 12, 80125 Naples, Italy
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Abstract
Cranial placodes are focal regions of thickened ectoderm in the head of vertebrate embryos that give rise to a wide variety of cell types, including elements of the paired sense organs and neurons in cranial sensory ganglia. They are essential for the formation of much of the cranial sensory nervous system. Although relatively neglected today, interest in placodes has recently been reawakened with the isolation of molecular markers for different stages in their development. This has enabled a more finely tuned approach to the understanding of placode induction and development and in some cases has resulted in the isolation of inducing molecules for particular placodes. Both morphological and molecular data support the existence of a preplacodal domain within the cranial neural plate border region. Nonetheless, multiple tissues and molecules (where known) are involved in placode induction, and each individual placode is induced at different times by a different combination of these tissues, consistent with their diverse fates. Spatiotemporal changes in competence are also important in placode induction. Here, we have tried to provide a comprehensive review that synthesises the highlights of a century of classical experimental research, together with more modern evidence for the tissues and molecules involved in the induction of each placode.
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Affiliation(s)
- C V Baker
- Division of Biology 139-74, California Institute of Technology, Pasadena, California, 91125, USA.
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46
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Yu X, St Amand TR, Wang S, Li G, Zhang Y, Hu YP, Nguyen L, Qiu MS, Chen YP. Differential expression and functional analysis of Pitx2 isoforms in regulation of heart looping in the chick. Development 2001; 128:1005-13. [PMID: 11222154 DOI: 10.1242/dev.128.6.1005] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pitx2, a bicoid-related homeobox gene, plays a crucial role in the left-right axis determination and dextral looping of the vertebrate developing heart. We have examined the differential expression and function of two Pitx2 isoforms (Pitx2a and Pitx2c) that differ in the region 5' to the homeodomain, in early chick embryogenesis. Northern blot and RT-PCR analyses indicated the existence of Pitx2a and Pitx2c but not Pitx2b in the developing chick embryos. In situ hybridization demonstrated a restricted expression of Pitx2c in the left lateral plate mesoderm (LPM), left half of heart tube and head mesoderm, but its absence in the extra-embryonic tissues where vasculogenesis occurs. RT-PCR experiments revealed that Pitx2a is absent in the left LPM, but is present in the head and extra-embryonic mesoderm. However, ectopic expression of either Pitx2c or Pitx2a via retroviral infection to the right LMP equally randomized heart looping direction. Mapping of the transcriptional activation function to the C terminus that is identical in both isoforms explained the similar results obtained by the gain-of-function approach. In contrast, elimination of Pitx2c expression from the left LMP by antisense oligonucleotide resulted in a randomization of heart looping, while treatment of embryos with antisense oligonucleotide specific to Pitx2a failed to generate similar effect. We further constructed RCAS retroviral vectors expressing dominant negative Pitx2 isoforms in which the C-terminal transcriptional activation domain was replaced by the repressor domain of the Drosophila Engrailed protein (En(r)). Ectopic expression of Pitx2c-En(r), but not Pitx2a-En(r), to the left LPM randomized the heart looping. The results thus demonstrate that Pitx2c plays a crucial role in the left-right axis determination and rightward heart looping during chick embryogenesis.
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Affiliation(s)
- X Yu
- Department of Cell and Molecular Biology, Molecular and Cell Biology Graduate Program and Center for Bioenvironmetal Research, Tulane University, New Orleans, LA 70118, USA
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47
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Dubreuil V, Hirsch MR, Pattyn A, Brunet JF, Goridis C. The Phox2b transcription factor coordinately regulates neuronal cell cycle exit and identity. Development 2000; 127:5191-201. [PMID: 11060244 DOI: 10.1242/dev.127.23.5191] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the vertebrate neural tube, cell cycle exit of neuronal progenitors is accompanied by the expression of transcription factors that define their generic and sub-type specific properties, but how the regulation of cell cycle withdrawal intersects with that of cell fate determination is poorly understood. Here we show by both loss- and gain-of-function experiments that the neuronal-subtype-specific homeodomain transcription factor Phox2b drives progenitor cells to become post-mitotic. In the absence of Phox2b, post-mitotic neuronal precursors are not generated in proper numbers. Conversely, forced expression of Phox2b in the embryonic chick spinal cord drives ventricular zone progenitors to become post-mitotic neurons and to relocate to the mantle layer. In the neurons thus generated, ectopic expression of Phox2b is sufficient to initiate a programme of motor neuronal differentiation characterised by expression of Islet1 and of the cholinergic transmitter phenotype, in line with our previous results showing that Phox2b is an essential determinant of cranial motor neurons. These results suggest that Phox2b coordinates quantitative and qualitative aspects of neurogenesis, thus ensuring that neurons of the correct phenotype are generated in proper numbers at the appropriate times and locations.
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Affiliation(s)
- V Dubreuil
- Laboratoire de Génétique et Physiologie du Développement, IBDM, CNRS-INSERM-Université de la Méditerranée-AP de Marseille, Campus de Luminy case 907, France
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48
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Smidt MP, Cox JJ, van Schaick HS, Coolen M, Schepers J, van der Kleij AM, Burbach JP. Analysis of three Ptx2 splice variants on transcriptional activity and differential expression pattern in the brain. J Neurochem 2000; 75:1818-25. [PMID: 11032870 DOI: 10.1046/j.1471-4159.2000.0751818.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Three different transcripts of the homeodomain gene termed pituitary homeobox (Ptx) 2 (Pitx2/Brx/Rieg/Solurshin/Arp) were cloned from different species encoding proteins belonging to the paired-like family of homeodomain proteins. Ptx2a (324 amino acids), Ptx2b (271 amino acids), and Ptx2c (318 amino acids) share the C terminus, including the homeodomain, and have different N termini. Here we report the comparative analysis of all three different Ptx2 splice variants for their transcriptional activity and their expression pattern in the adult rat brain. Ptx2 is able to trans-activate via different model promoters in different cell lines. A mild difference in trans-activating potential is observed among the splice variants, but the underlying mechanism is at present unknown. It is surprising that all Ptx2 transcripts displayed an identical expression pattern in the brain. This markedly restricted pattern is limited to the following brain areas: the anterior and intermediate lobes of the pituitary gland, the subthalamic nucleus, the posterior hypothalamic nucleus, the mammillary bodies, the red nucleus, and the deep gray layer of the superior colliculus. The data presented suggest that all variants of Ptx2 are involved in the development and regulation of distinct neuronal cell groups and the pituitary gland.
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Affiliation(s)
- M P Smidt
- Section of Molecular Neuroscience, Department of Medical Pharmacology, Rudolf Magnus Institute for Neurosciences, Utrecht University Medical Center, Utrecht, The Netherlands
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49
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Martínez S, Puelles L. Neurogenetic compartments of the mouse diencephalon and some characteristic gene expression patterns. Results Probl Cell Differ 2000; 30:91-106. [PMID: 10857186 DOI: 10.1007/978-3-540-48002-0_4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- S Martínez
- Department of Morphological Sciences, University of Murcia, Spain.
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50
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Poulin G, Lebel M, Chamberland M, Paradis FW, Drouin J. Specific protein-protein interaction between basic helix-loop-helix transcription factors and homeoproteins of the Pitx family. Mol Cell Biol 2000; 20:4826-37. [PMID: 10848608 PMCID: PMC85932 DOI: 10.1128/mcb.20.13.4826-4837.2000] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Homeoproteins and basic helix-loop-helix (bHLH) transcription factors are known for their critical role in development and cellular differentiation. The pituitary pro-opiomelanocortin (POMC) gene is a target for factors of both families. Indeed, pituitary-specific transcription of POMC depends on the action of the homeodomain-containing transcription factor Pitx1 and of bHLH heterodimers containing NeuroD1. We now show lineage-restricted expression of NeuroD1 in pituitary corticotroph cells and a direct physical interaction between bHLH heterodimers and Pitx1 that results in transcriptional synergism. The interaction between the bHLH and homeodomains is restricted to ubiquitous (class A) bHLH and to the Pitx subfamily. Since bHLH heterodimers interact with Pitx factors through their ubiquitous moiety, this mechanism may be implicated in other developmental processes involving bHLH factors, such as neurogenesis and myogenesis.
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Affiliation(s)
- G Poulin
- Laboratoire de Génétique Moléculaire, Institut de Recherches Cliniques de Montréal, Montréal, Québec H2W 1R7, Canada
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