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ABSTRACT: The members of the Pitx family of homeobox transcription factors have been involved in many aspects of vertebrate embryogenesis, like for example, development of teeth, eyes and limbs. We previously reported expression patterns and function of Pitx2c in the generation of laterality and asymmetric morphogenesis of heart and gastro-intestinal tract in mouse, frog and zebrafish (Development 126 (1999) 1225; Mech. Dev. 90 (2000) 41). Here we describe the differential expression of Pitx1, Pitx2b and Pitx2c during anterior ectodermal pattern formation and differentiation of cement gland, stomodeum and pituitary in the frog Xenopus laevis.
Mechanisms of Development 10/2001; 107(1-2):191-4. · 2.83 Impact Factor
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ABSTRACT: The mucus secreting cement gland is the anterior-most ectodermal organ of the Xenopus embryo. The homeobox genes Pltx1 and Pitx2c are expressed in the cement gland primordium. Misexpression of both genes induced ectopic cement gland tissue in whole embryos and transcription of the marker genes Xag1 and Xag2 in animal cap explant cultures. Antisense morpholino oligonucleotides against Pitx1 and Pitx2c inhibited ectopic cement gland formation induced by otx2. Gene knock downs generated by morpholino oligonucleotides were specific and could be rescued by coinjection of Pitx mRNAs. These data demonstrate for the first time the requirement of specific genes for cement gland formation by loss-of-function experiments. genesis 30:144--148, 2001.
genesis 08/2001; 30(3):144-8. · 2.53 Impact Factor
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ABSTRACT: The homeobox gene Pitx2 has been characterized as a mediator of left-right signaling in heart, gut, and lung morphogenesis. However, the relationship between the developmental role of Pitx2 and its expression pattern at the organ level has not been explored. In this study we focus on the role of Pitx2 in heart morphogenesis. Chicken Pitx2 transcripts are present in the left portion of the cardiac crescent and in the left side of the heart tube. Through looping Pitx2 is present in the left atrium, in the ventral portion of the ventricles and in the left-ventral part of the outflow tract. Mouse Pitx2 shows a similar developmental profile of expression. To test whether Pitx2 represents a lineage marker we have tagged the left portion of the chicken cardiac tube with fluorescent DiD. Labeled cells were found at HH16 in the left atrium and in the ventral region of the ventricles and the outflow tract. In the iv/iv mouse model of cardiac heterotaxia Pitx2 was abnormally expressed in the atrial and in the ventricular chambers. Furthermore, altered Pitx2 expression correlated with the occurrence of DORV. Our data reveal the existence of molecular isomerism not only in the atrial, but also in the ventricular compartment of the heart.
Developmental Biology 04/2001; 231(1):252-64. · 4.07 Impact Factor
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ABSTRACT: The homeobox gene goosecoid, originally identified in Xenopus, is expressed in the organizer or its equivalent during gastrulation in the frog, chick, zebrafish and mouse. To investigate the role of goosecoid in mouse development, we have generated embryonic stem cells that stably overexpress the murine homolog of goosecoid. These cells show a repression of the gastrulation-associated gene Brachyury. Interestingly, repression of Brachyury is conserved between Xenopus and mouse despite the lack of conservation of the Brachyury promoter. Further characterization of the goosecoid-overexpressing ES cells revealed that they maintain the expression of stage-specific embryonic antigen-1, and teratomas derived from goosecoid-overexpressing cells show the presence of cell types derived from all three germ layers. Some highly chimeric mice derived from goosecoid-overexpressing cells displayed skull defects. These observations suggest that goosecoid may play a role in specification of anterior mesendodermal fates and specifically in mouse craniofacial development.
The International Journal of Developmental Biology 05/2000; 44(3):279-88. · 2.82 Impact Factor
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ABSTRACT: BAG-1 is a family of proteins with diverse activities that range in cultured cells from protection against programmed cell death through to regulation of steroid hormone action. At least three proteins (BAG-1L, BAG-1M and BAG-1) are encoded by the Bag-1 mRNA through the use of alternative translation-initiation sites. To assess the in vivo function of these factors, we have used in situ hybridization and immunohistochemical techniques to determine the distribution of Bag-1 transcript and proteins during mouse development. Bag-1 mRNA was identified in several organs with cartilaginous tissues showing the highest expression levels. The level of expression at some of these sites was downregulated during the course of development. In the immunohistochemical studies, antibodies directed against the BAG-1 proteins stained all the sites identified in the in situ hybridization studies although isoform-specific differences were observed. BAG-1L specific antibody showed ubiquitous staining as early as day 10.5 post-coitum but there was a progressive restriction during subsequent stages of embryogenesis. On the contrary, an antibody that preferentially recognized the other isoforms only stained the mouse myocardium in the early developmental stages before finally recognizing additional organs later on in development. These results demonstrate a stage- and site-specific expression of the BAG-1 isoforms during mouse development.
Mechanisms of Development 04/2000; 91(1-2):355-9. · 2.83 Impact Factor
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ABSTRACT: During vertebrate left-right development the homeobox gene Pitx2 serves as a mediator between transient nodal signaling in the left lateral plate mesoderm (l-LPM) and asymmetric organ morphogenesis. Misexpression of Pitx2 in chick and frog led to alteration of organ situs. Here we report the presence of different Pitx2 isoforms in mouse and frog. Pitx2c but not Pitx2a or Pitx2b was asymmetrically expressed in the l-LPM, heart and gut, and was specifically induced by nodal in Xenopus animal cap explant cultures and whole embryos. Pitx2c induced its own transcription, suggesting a maintenance mechanism following the down-regulation of nodal in the l-LPM. Pitx2c thus represents the left-specific isoform involved in vertebrate left-right asymmetry.
Mechanisms of Development 02/2000; 90(1):41-51. · 2.83 Impact Factor
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U Gaio,
A Schweickert,
A Fischer,
A N Garratt,
T Müller,
C Ozcelik,
W Lankes,
M Strehle,
S Britsch, M Blum,
C Birchmeier
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ABSTRACT: During vertebrate embryogenesis, a left-right axis is established. The heart, associated vessels and inner organs adopt asymmetric spatial arrangements and morphologies. Secreted growth factors of the TGF-beta family, including nodal, lefty-1 and lefty-2, play crucial roles in establishing left-right asymmetries [1] [2] [3]. In zebrafish, nodal signalling requires the presence of one-eyed pinhead (oep), a member of the EGF-CFC family of membrane-associated proteins [4]. We have generated a mutant allele of cryptic, a mouse EGF-CFC gene [5]. Homozygous cryptic mutants developed to birth, but the majority died during the first week of life because of complex cardiac malformations such as malpositioning of the great arteries, and atrial-ventricular septal defects. Moreover, laterality defects, including right isomerism of the lungs, right or left positioning of the stomach and splenic hypoplasia were observed. Nodal gene expression in the node was initiated in cryptic mutant mice, but neither nodal, lefty-2 nor Pitx2 were expressed in the left lateral plate mesoderm. The laterality defects observed in cryptic(-/-) mice resemble those of mice lacking the type IIB activin receptor or the homeobox-containing factor Pitx2 [6] [7] [8] [9], and are reminiscent of the human asplenic syndrome [10]. Our results provide genetic evidence for a role of cryptic in the signalling cascade that determines left-right asymmetry.
Current Biology 12/1999; 9(22):1339-42. · 9.65 Impact Factor
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ABSTRACT: During vertebrate embryonic development, the organs of the chest and abdomen, heart, lung and gastrointestinal tract, acquire characteristic asymmetric positions with respect to the left-right body axis. In the beginning of the 20th century Hans Spemann and his co-workers described manipulations of amphibian embryos which resulted in inversion of organ laterality in a predictable manner. Hedwig Wilhelmi concluded from these experiments that determinants on the left side of the embryo specify laterality, and Meyer postulated that a mediator should transfer this positional information to the forming heart. In this review we discuss the classical experiments in the light of recent advances in the molecular understanding of left-right development, with a focus on the mediator role of the homeobox gene Pitx2.
Cellular and molecular biology 08/1999; 45(5):505-16. · 0.98 Impact Factor
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ABSTRACT: Retinoic acid (RA) plays a pivotal role during vertebrate development, both as morphogen and as potent teratogen. While RA function in axial development has been extensively studied, little is known about the genetic control of RA teratogenicity. The knockout of the homeobox gene goosecoid in the mouse revealed similarities to RA induced embryopathy. We show that RA treatment of mouse gastrula embryos in vitro and of E10.5 embryos in utero led to a rapid but transient down-regulation of goosecoid expression. Repression was dependent on retinoid X receptors (RXR). BMP-4 was repressed by RA-treatment as well, both in embryos and in F9 teratocarcinoma cells. Our data suggest that both goosecoid and BMP-4 function as mediators of RA teratogenicity in mouse embryos.
Cellular and molecular biology 08/1999; 45(5):617-29. · 0.98 Impact Factor
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M Campione,
H Steinbeisser,
A Schweickert,
K Deissler,
F van Bebber,
L A Lowe,
S Nowotschin,
C Viebahn,
P Haffter,
M R Kuehn, M Blum
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ABSTRACT: Left-right asymmetry in vertebrates is controlled by activities emanating from the left lateral plate. How these signals get transmitted to the forming organs is not known. A candidate mediator in mouse, frog and zebrafish embryos is the homeobox gene Pitx2. It is asymmetrically expressed in the left lateral plate mesoderm, tubular heart and early gut tube. Localized Pitx2 expression continues when these organs undergo asymmetric looping morphogenesis. Ectopic expression of Xnr1 in the right lateral plate induces Pitx2 transcription in Xenopus. Misexpression of Pitx2 affects situs and morphology of organs. These experiments suggest a role for Pitx2 in promoting looping of the linear heart and gut.
Development 04/1999; 126(6):1225-34. · 6.60 Impact Factor
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ABSTRACT: The homeobox gene goosecoid is expressed in the Spemann organizer tissue of gastrulating vertebrate embryos, and in the craniofacial region and appendicular skeleton during organogenesis. The goosecoid knockout mutant mouse revealed defects related to the second phase of expression. Here we describe new expression sites in the developing trachea and external genitalia, and in the developing shoulder and hip joint with their associated ligaments and muscles. We show that mutant mice display abnormalities in the forming trachea and appendicular skeleton related to these sites of gene expression. In addition, we discuss evidence for the existence of at least three goosecoid genes in vertebrates, which may account for the lack of a defect of axial patterning in goosecoid mutant mice.
Developmental Dynamics 05/1998; 211(4):374-81. · 2.54 Impact Factor
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ABSTRACT: Androgen receptor (AR) is a member of the nuclear receptor superfamily which acts as a ligand-dependent transcription factor (Beato, M., Herrlich, P., Schütz, 1989. Steroid hormone receptors: many actors in search of a plot. Cell 83, 851-857). It plays a pivotal role in sexual development and reproduction (Wilson, J.D., Griffin, J.E., George, F.W., Leshin, M., 1981. The role of gonadal steroids in sexual differentiation. Rec. Prog. Horm. Res. 37, 1-39; Jost, A., 1990. Hormonal control of the masculinization of the body. In: Baulieu, E.E., Kelly, D.A., (Eds.), Hormones, from Molecules to Disease. Chapman and Hall, New York and London, pp. 439-442.). Mutations in the AR sequence cause a number of physiological disorders, such as partial and complete androgen insensitivity syndromes, that lead to abnormal sexual development (Patterson, M.N., McPhaul, M.J., Hughes, I.A., 1994. Androgen insensitivity syndrome. Ballière's Clin. Endocrinol. Metab. 8, 379-404.). There are indications that AR may also have other functions. For example, structural alterations of the AR sequence have been implicated in prostate cancer (Visakorpi, T., Huytinen, E., Koivisto, P., Tanner, M., Keinänen, R., Palmberg, C., Palotie, A., Tammela, T., Isola, J., Kallioniemi, O.-P., 1995. In vivo amplification of the androgen receptor gene and progression of human prostate cancer. Nature Genet. 9, 401-406.) and in the development of spinal and bulbar muscular atrophy, a neurodegenerative disease (Kennedy, W.R., Alter, M., Sung, J.H., 1968. Progressive proximal spinal and bulbar muscular atrophy of late onset: a sex-linked recessive trait. Neurology 18, 671-680.). Here, we have investigated the spatial and temporal expression of AR during mouse organogenesis by in situ hybridisation. We demonstrate that AR transcripts occur in the developing external genitalia, pituitary, adrenals, kidneys and musculus levator ani, in addition to the known expression sites in the Wolffian ducts and its derivatives and during development of the mammary glands.
Mechanisms of Development 03/1998; 72(1-2):175-8. · 2.83 Impact Factor
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ABSTRACT: The homeobox gene goosecoid has been implicated to play a central role in the Spemann organizer tissue of the vertebrate embryo. Misexpression of goosecoid on the ventral side of a Xenopus laevis gastrula embryo was shown to result in a partial duplication of the primary body axis, reminiscent of the Spemann organizer graft. Normal embryonic development thus requires tight temporal and spatial control of genes instrumental for organizer function. In the present study we investigated the transcriptional control of goosecoid gene expression. Sequence analysis of the mouse and human promoter region revealed the presence of two palindromic binding elements for homeobox genes of the prd type to which goosecoid belongs. We show that Goosecoid protein can bind to these sites in vitro. By using reporter gene constructs of the human and mouse promoter, we demonstrate that Goosecoid can act as a repressor of its own promoter activity in transient co-transfection experiments in mouse P19 cells and in Xenopus embryos. Autorepression depends on the presence of the homeodomain and is mediated through the prd element more proximal to the transcriptional start site. Our results suggest a role for goosecoid in restricting organizer activity in the vertebrate gastrula embryo.
Journal of Biological Chemistry 02/1998; 273(1):627-35. · 4.77 Impact Factor
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ABSTRACT: The homeobox gene goosecoid marks the Spemann organizer in vertebrate gastrula embryos, and is expressed in the craniofacial region, body wall and limbs during organogenesis. Mouse mutants of goosecoid displayed a variety of phenotypes related to the expression pattern at mid-embryogenesis. These defects included loss of the tympanic ring and malformation of the malleus, phenotypes which were reminiscent of the teratogenic effects of retinoic acid (RA). Here we investigated the correlation of goosecoid gene expression and RA-teratogenicity following treatment of mouse embryos in vivo at embryonic day (E) 8 + 5 h. We found that goosecoid was specifically affected at E10.5 in branchial arches I and II. Expression was either reduced to background levels or restricted to the branchial cleft region. This change in goosecoid gene expression correlated with a loss of middle ear ossicles and a partial or complete deletion of the tympanic ring, suggesting a role for goosecoid in executing the RA teratogenic effects.
Biochemical and Biophysical Research Communications 07/1997; 235(3):748-53. · 2.48 Impact Factor
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ABSTRACT: Specific signaling molecules play a pivotal role in the induction and specification of tissues during early vertebrate embryogenesis. BMP-4 specifies ventral mesoderm differentiation and inhibits neural induction in Xenopus, whereas three molecules secreted from the organizer, noggin, follistatin and chordin dorsalize mesoderm and promote neural induction. Here we report that follistatin antagonizes the activities of BMP-4 in frog embryos and mouse teratocarcinoma cells. In Xenopus embryos follistatin blocks the ventralizing effect of BMP-4. In mouse P19 cells follistatin promotes neural differentiation. BMP-4 antagonizes the action of follistatin and prevents neural differentiation. In addition we show that the follistatin and BMP-4 proteins can interact directly in vitro. These data provide evidence that follistatin might play a role in modulating BMP-4 activity in vivo.
Mechanisms of Development 05/1997; 63(1):39-50. · 2.83 Impact Factor
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ABSTRACT: The goosecoid gene encodes a homeodomain-containing protein that has been identified in a number of species and has been implicated in a variety of key developmental processes. Initially suggested to be involved in organizing the embryo during early development, goosecoid has since been demonstrated to be expressed during organogenesis-most notably in the head, the limbs and the ventrolateral body wall. To investigate the role of goosecoid in embryonic development, we have inactivated the gene by gene targeting to generate mice mutant for the goosecoid gene. Mice that are homozygous for the goosecoid mutation do not display a gastrulation phenotype and are born; however, they do not survive more than 24 hours. Analysis of the homozygotes revealed numerous developmental defects affecting those structures in which goosecoid is expressed during its second (late) phase of embryonic expression. Predominantly, these defects involve the lower mandible and its associated musculature including the tongue, the nasal cavity and the nasal pits, as well as the components of the inner ear (malleus, tympanic ring) and the external auditory meatus. Although the observed phenotype is in accordance with the late expression domains of goosecoid in wild-type embryos, we suggest that the lack of an earlier phenotype is the result of functional compensation by other genes.
Development 10/1995; 121(9):2917-22. · 6.60 Impact Factor
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ABSTRACT: Goosecoid is a homeobox gene first isolated from a Xenopus dorsal lip cDNA library. Homologous genes have been isolated from mouse, zebrafish, and chick. In all species examined, the gene is expressed and plays an important role during the process of gastrulation in early embryonic development. We report here the cloning of the human goosecoid gene (GSC) from a genomic library and the sequence of its encoded protein. The genomic organization and protein sequence of the human gene are highly conserved with respect to those of its Xenopus and mouse counterparts: all three genes consist of three exons, with conserved exon-intron boundaries; the sequence of the homeodomain is 100% conserved in most vertebrates. Using somatic cell hybrid and chromosomal in situ hybridization, the gene was mapped to chromosome 14q32.1.
Genomics 06/1994; 21(2):388-93. · 3.02 Impact Factor
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ABSTRACT: After an earlier, transient phase of expression in the developing primitive streak of 6.4- to 6.8-day mouse embryos, the homeobox gene goosecoid is now shown to be expressed in a later phase of mouse development, from 10.5 days onwards. The later, spatially restricted domains of goosecoid expression are detected in the head, limbs and ventrolateral body wall. At all sites, the domains of expression are first detected in undifferentiated tissue, and then expression persists as these tissues undergo subsequent morphogenesis. For example, goosecoid expression is noted in the first branchial arch at 10.5 days, and then expression persists as this tissue undergoes morphogenesis to form the lower jaw and the body of the tongue. Expression in tissues around the first branchial cleft persists as these undergo morphogenesis to form the base of the auditory meatus and eustachian tube. Expression in tissues around the newly formed nasal pits persists as these elongate to form the nasal chambers. Expression in the ventral epithelial lining of the otic vesicle persists as this eventually gives rise to the non-sensory epithelium of the cochlea. Expression in the proximal limb buds and ventrolateral body wall persists as these tissues undergo morphogenesis to form proximal limb structures and ventral ribs respectively. Our findings lead us to suggest that the goosecoid gene product plays a role in spatial programming within discrete embryonic fields, and possibly lineage compartments, during organogenesis stages of mouse development.
Development 03/1993; 117(2):769-78. · 6.60 Impact Factor
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ABSTRACT: We describe transgenic mouse lines that express lacZ under the control of the Hox 3.3 Promoter II. The correct anterior boundary can be fixed by 3.6 kb of promoter DNA (plus 1.6 kb of 5' transcribed sequences), both in tissues of ectodermal and mesodermal origin. The posterior border, however, is not respected, and lacZ expression continues into the tail region. One line has particularly strong graded expression in the anterior proximal limb bud. Other lines, containing a shorter promoter fragment (0.6 kb), have ectopic expression in the head region, including one line that has expression in the anterior half of the retina. Such mouse lines make it possible to molecularly distinguish cells in regions of the embryo that look otherwise identical and may be useful in studying the establishment of molecular differences in the mouse embryo.
Mechanisms of Development 01/1993; 39(3):171-80. · 2.83 Impact Factor
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ABSTRACT: Mouse goosecoid is a homeobox gene expressed briefly during early gastrulation. Its mRNA accumulates as a patch on the side of the epiblast at the site where the primitive streak is first formed. goosecoid-expressing cells are then found at the anterior end of the developing primitive streak, and finally in the anteriormost mesoderm at the tip of the early mouse gastrula, a region that gives rise to the head process. Treatment of early mouse embryos with activin results in goosecoid mRNA accumulation in the entire epiblast, suggesting that a localized signal induces goosecoid expression during development. Transplantation experiments indicate that the tip of the murine early gastrula is the equivalent of the organizer of the amphibian gastrula.
Cell 07/1992; 69(7):1097-106. · 32.40 Impact Factor
