Functions of RARs and RXRs in vivo: Genetic dissection of the retinoid signaling pathway

2003 ◽  
Vol 75 (11-12) ◽  
pp. 1709-1732 ◽  
Author(s):  
Manuel Mark ◽  
Pierre Chambon
Keyword(s):  
Signaling Pathway ◽  
Gene Networks ◽  
Es Cells ◽  
Embryonic Stem ◽  
Postnatal Life ◽  
Active Metabolites ◽  
Genetic Studies ◽  
Retinoid Signaling

Retinoids, the active metabolites of vitamin A, regulate complex gene networks involved in vertebrate morphogenesis, growth, cellular differentiation, and homeostasis. They are used for the treatment of skin disorders and as chemopreventive agents for certain cancers. Molecular biology and genetic studies performed during the last 15 years in vitro, using either acellular systems or transfected cells, have shown that retinoid actions are mediated through heterodimers between the 8 major RARα, β, and γ; isoforms and the 6 major RXRα, β and γ isoforms that belong to the nuclear receptor (NR) superfamily, and act as ligand-dependent transcriptional regulators. Furthermore, RXRs not only heterodimerize with RARs, but also with numerous other members of the NR superfamily. As in vitro studies are carried out under nonphysiological conditions, they only indicate what is possible, but not necessarily what is actually occurring in vivo. Therefore, mutations have been introduced by homologous recombination (HR) in F9 embryonal carcinoma (EC) cells, a cell-autonomous system that differentiates in the presence of RA, in order to disrupt RAR and RXR genes and establish their cellular and molecular functions in RA-induced differentiation. However, genetic approaches in the animal should be used to determine the function of retinoid receptors under truly physiological conditions. HR in embryonic stem (ES) cells, has therefore been used to generate null mutations of the various RARs and RXRs in the mouse germline. As reviewed here, the generation of such RAR and RXR germline mutations, combined with pharmacological approaches to block the RA signaling pathway, has provided many valuable insights on the developmental functions of RA receptors. However, due to (i) the complexity in "hormonal" signaling through transduction by the multiple RARs and RXRs, (ii) the functional redundancies (possibly artefactually generated by the mutations) within receptor isotypes belonging to a given gene family, and (iii) in utero or postnatal lethality of certain germline null mutations, these genetic studies through germline mutagenesis have failed to reveal many of the physiological functions of RARs and RXRs, notably in adults. We conclude that spatio-temporally controlled somatic mutations generated in animal models in given cell-types/tissues and at chosen times during pre- and postnatal life, are required to reveal the physiological and pathophysiological functions of the receptor genes involved in the retinoid signaling pathway throughout the life of the mouse.

scholarly journals Function of retinoic acid receptors during embryonic development

2009 ◽  
Vol 7 (1) ◽  
pp. nrs.07002 ◽  
Author(s):  
Manuel Mark ◽  
Norbert B. Ghyselinck ◽  
Pierre Chambon
Keyword(s):  
Gene Networks ◽  
Embryonic Stem ◽  
Cell Types ◽  
Prenatal Development ◽  
Postnatal Life ◽  
Active Metabolites ◽  
Physiological Functions ◽  
Retinoid Receptors

Retinoids, the active metabolites of vitamin A, regulate complex gene networks involved in vertebrate morphogenesis, growth, cellular differentiation and homeostasis. Studies performed in vitro, using either acellular systems or transfected cells, have shown that retinoid actions are mediated through heterodimers between the RAR and RXR nuclear receptors. However, in vitro studies indicate what is possible, but not necessarily what is actually occurring in vivo, because they are performed under non-physiological conditions. Therefore, genetic approaches in the animal have been be used to determine the physiological functions of retinoid receptors. Homologous recombination in embryonic stem cells has been used to generate germline null mutations of the RAR- and RXR-coding genes in the mouse. As reviewed here, the generation of such germline mutations, combined with pharmacological approaches to block the RA signalling pathway, has provided genetic evidence that RAR/RXR heterodimers are indeed the functional units transducing the RA signal during prenatal development. However, due to (i) the complexity in “hormonal” signalling through transduction by the multiple RARs and RXRs, (ii) the functional redundancies (possibly artefactually generated by the mutations) within receptor isotypes belonging to a given family, and (iii) in utero or early postnatal lethality of certain germline null mutations, these genetic studies have failed to reveal all the physiological functions of RARs and RXRs, notably in adults. Spatio-temporally-controlled somatic mutations generated in given cell types/tissues and at chosen times during postnatal life, will be required to reveal all the functions of RAR and RXR throughout the lifetime of the mouse.

Wnt/(beta)-catenin signaling regulates the expression of the homeobox gene Cdx1 in embryonic intestine

Development ◽  
2000 ◽  
Vol 127 (17) ◽  
pp. 3805-3813 ◽  
Author(s):  
H. Lickert ◽  
C. Domon ◽  
G. Huls ◽  
C. Wehrle ◽  
I. Duluc ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Intestinal Epithelium ◽  
Es Cells ◽  
Embryonic Stem ◽  
Early Period ◽  
Homeobox Gene ◽  
Beta Catenin ◽  
Mammalian Development

During mammalian development, the Cdx1 homeobox gene exhibits an early period of expression when the embryonic body axis is established, and a later period where expression is restricted to the embryonic intestinal endoderm. Cdx1 expression is maintained throughout adulthood in the proliferative cell compartment of the continuously renewed intestinal epithelium, the crypts. In this study, we provide evidence in vitro and in vivo that Cdx1 is a direct transcriptional target of the Wnt/(beta)-catenin signaling pathway. Upon Wnt stimulation, expression of Cdx1 can be induced in mouse embryonic stem (ES) cells as well as in undifferentiated rat embryonic endoderm. Tcf4-deficient mouse embryos show abrogation of Cdx1 protein in the small intestinal epithelium, making Tcf4 the likely candidate to transduce Wnt signal in this part of gut. The promoter region of the Cdx1 gene contains several Tcf-binding motifs, and these bind Tcf/Lef1/(beta)-catenin complexes and mediate (beta)-catenin-dependent transactivation. The transcriptional regulation of the homeobox gene Cdx1 in the intestinal epithelium by Wnt/(beta)-catenin signaling underlines the importance of this signaling pathway in mammalian endoderm development.

Brachyury - a gene affecting mouse gastrulation and early organogenesis

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 157-165 ◽  
Author(s):  
R. S. P. Beddington ◽  
P. Rashbass ◽  
V. Wilson
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
Primitive Streak ◽  
Coat Colour ◽  
Es Cell ◽  
Wild Type ◽  
Mesoderm Cell ◽  
Rostrocaudal Axis

Mouse embryos that are homozygous for the Brachyury (T) deletion die at mid-gestation. They have prominent defects in the notochord, the allantois and the primitive streak. Expression of the T gene commences at the onset of gastrulation and is restricted to the primitive streak, mesoderm emerging from the streak, the head process and the notochord. Genetic evidence has suggested that there may be an increasing demand for T gene function along the rostrocaudal axis. Experiments reported here indicate that this may not be the case. Instead, the gradient in severity of the T defect may be caused by defective mesoderm cell movements, which result in a progressive accumulation of mesoderm cells near the primitive streak. Embryonic stem (ES) cells which are homozygous for the T deletion have been isolated and their differentiation in vitro and in vivo compared with that of heterozygous and wild-type ES cell lines. In +/+ ↔ T/T ES cell chimeras the Brachyury phenotype is not rescued by the presence of wild-type cells and high level chimeras show most of the features characteristic of intact T/T mutants. A few offspring from blastocysts injected with T/T ES cells have been born, several of which had greatly reduced or abnormal tails. However, little or no ES cell contribution was detectable in these animals, either as coat colour pigmentation or by isozyme analysis. Inspection of potential +/+ ↔ T/T ES cell chimeras on the 11th or 12th day of gestation, stages later than that at which intact T/T mutants die, revealed the presence of chimeras with caudal defects. These chimeras displayed a gradient of ES cell colonisation along the rostrocaudal axis with increased colonisation of caudal regions. In addition, the extent of chimerism in ectodermal tissues (which do not invaginate during gastrulation) tended to be higher than that in mesodermal tissues (which are derived from cells invaginating through the primitive streak). These results suggest that nascent mesoderm cells lacking the T gene are compromised in their ability to move away from the primitive streak. This indicates that one function of the T genemay be to regulate cell adhesion or cell motility properties in mesoderm cells. Wild-type cells in +/+ ↔ T/T chimeras appear to move normally to populate trunk and head mesoderm, suggesting that the reduced motility in T/T cells is a cell autonomous defect

scholarly journals Generation and Characterization of Smac/DIABLO-Deficient Mice

2002 ◽  
Vol 22 (10) ◽  
pp. 3509-3517 ◽  
Author(s):  
Hitoshi Okada ◽  
Woong-Kyung Suh ◽  
Jianping Jin ◽  
Minna Woo ◽  
Chunying Du ◽  
...  
Keyword(s):  
Physiological Function ◽  
Es Cells ◽  
Embryonic Stem ◽  
Caspase Activation ◽  
Proapoptotic Protein ◽  
Apoptosis Proteins ◽  
Deficient Mice

ABSTRACT The mitochondrial proapoptotic protein Smac/DIABLO has recently been shown to potentiate apoptosis by counteracting the antiapoptotic function of the inhibitor of apoptosis proteins (IAPs). In response to apoptotic stimuli, Smac is released into the cytosol and promotes caspase activation by binding to IAPs, thereby blocking their function. These observations have suggested that Smac is a new regulator of apoptosis. To better understand the physiological function of Smac in normal cells, we generated Smac-deficient (Smac−/− ) mice by using homologous recombination in embryonic stem (ES) cells. Smac−/− mice were viable, grew, and matured normally and did not show any histological abnormalities. Although the cleavage in vitro of procaspase-3 was inhibited in lysates of Smac−/− cells, all types of cultured Smac−/− cells tested responded normally to all apoptotic stimuli applied. There were also no detectable differences in Fas-mediated apoptosis in the liver in vivo. Our data strongly suggest the existence of a redundant molecule or molecules capable of compensating for a loss of Smac function.

scholarly journals Dickkopf Wnt signaling pathway inhibitor 1 regulates the differentiation of mouse embryonic stem cells in vitro and in vivo

2015 ◽  
Vol 13 (1) ◽  
pp. 720-730 ◽  
Author(s):  
LIPING OU ◽  
LIAOQIONG FANG ◽  
HEJING TANG ◽  
HAI QIAO ◽  
XIAOMEI ZHANG ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Wnt Signaling ◽  
Signaling Pathway ◽  
Wnt Signaling Pathway ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cells

Abstract 1457: IGFBP-4-Mediated Wnt Inhibition is Required for Cardiac Myogenesis

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Weidong Zhu ◽  
Ichiro Shiojima ◽  
Li Zhi ◽  
Hiroyuki Ikeda ◽  
Masashi Yoshida ◽  
...  
Keyword(s):  
Growth Factor ◽  
Wnt Signaling ◽  
Heart Diseases ◽  
Es Cells ◽  
Embryonic Stem ◽  
Cardiomyocyte Differentiation ◽  
Canonical Wnt Signaling ◽  
Canonical Wnt

Insulin-like growth factor-binding proteins (IGFBPs) bind to and modulate the actions of insulin-like growth factors (IGFs). Although some of the effects of IGFBPs appear to be independent of IGFs, the precise mechanisms of IGF-independent actions of IGFBPs are largely unknown. In this study we demonstrate that IGFBP-4 is a novel cardiogenic growth factor. IGFBP-4 enhanced cardiomyocyte differentiation of P19CL6 embryonal carcinoma cells and embryonic stem (ES) cells in vitro. Conversely, siRNA-mediated knockdown of IGFBP-4 in P19CL6 cells or ES cells attenuated cardiomyocyte differentiation, and morpholino-mediated knockdown of IGFBP-4 in Xenopus embryos resulted in severe cardiac defects and complete absence of the heart in extreme cases. We also demonstrate that the cardiogenic effect of IGFBP-4 was independent of its IGF-binding activity but was mediated by the inhibitory effect on canonical Wnt signaling. IGFBP-4 physically interacted with a Wnt receptor Frizzled 8 (Frz8) and a Wnt co-receptor low-density lipoprotein receptor-related protein 6 (LRP6), and inhibited the binding of Wnt3A to Frz8 and LRP6. Moreover, the cardiogenic defects induced by IGFBP-4 knockdown both in vitro and in vivo was rescued by simultaneous inhibition of canonical Wnt signaling. Thus, IGFBP-4 is an inhibitor of the canonical Wnt signaling, and Wnt inhibition by IGFBP-4 is required for cardiogenesis. The present study provides a molecular link between IGF signaling and Wnt signaling, and suggests that IGFBP-4 may be a novel therapeutic target for heart diseases.

Altered imprinted gene methylation and expression in completely ES cell-derived mouse fetuses: association with aberrant phenotypes

Development ◽  
1998 ◽  
Vol 125 (12) ◽  
pp. 2273-2282 ◽  
Author(s):  
W. Dean ◽  
L. Bowden ◽  
A. Aitchison ◽  
J. Klose ◽  
T. Moore ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Es Cells ◽  
Embryonic Stem ◽  
Upstream Region ◽  
Imprinted Genes ◽  
Epigenetic Alterations ◽  
Es Cell ◽  
Biallelic Expression

In vitro manipulation of preimplantation mammalian embryos can influence differentiation and growth at later stages of development. In the mouse, culture of embryonic stem (ES) cells affects their totipotency and may give rise to fetal abnormalities. To investigate whether this is associated with epigenetic alterations in imprinted genes, we analysed two maternally expressed genes (Igf2r, H19) and two paternally expressed genes (Igf2, U2af1-rs1) in ES cells and in completely ES cell-derived fetuses. Altered allelic methylation patterns were detected in all four genes, and these were consistently associated with allelic changes in gene expression. All the methylation changes that had arisen in the ES cells persisted on in vivo differentiation to fetal stages. Alterations included loss of methylation with biallelic expression of U2af1-rs1, maternal methylation and predominantly maternal expression of Igf2, and biallelic methylation and expression of Igf2r. In many of the ES fetuses, the levels of H19 expression were strongly reduced, and this biallelic repression was associated with biallellic methylation of the H19 upstream region. Surprisingly, biallelic H19 repression was not associated with equal levels of Igf2 expression from both parental chromosomes, but rather with a strong activation of the maternal Igf2 allele. ES fetuses derived from two of the four ES lines appeared developmentally compromised, with polyhydramnios, poor mandible development and interstitial bleeding and, in chimeric fetuses, the degree of chimerism correlated with increased fetal mass. Our study establishes a model for how early embryonic epigenetic alterations in imprinted genes persist to later developmental stages, and are associated with aberrant phenotypes.

scholarly journals Multipotent fetal-derived Cdx2 cells from placenta regenerate the heart

2019 ◽  
pp. 201811827 ◽  
Author(s):  
Sangeetha Vadakke-Madathil ◽  
Gina LaRocca ◽  
Koen Raedschelders ◽  
Jesse Yoon ◽  
Sarah J. Parker ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Contractile Function ◽  
Es Cells ◽  
Embryonic Stem ◽  
Lineage Tracing ◽  
Cardiac Differentiation ◽  
Cell Based Therapy ◽  
Allogeneic Cell Therapy

The extremely limited regenerative potential of adult mammalian hearts has prompted the need for novel cell-based therapies that can restore contractile function in heart disease. We have previously shown the regenerative potential of mixed fetal cells that were naturally found migrating to the injured maternal heart. Exploiting this intrinsic mechanism led to the current hypothesis that Caudal-type homeobox-2 (Cdx2) cells in placenta may represent a novel cell type for cardiac regeneration. Using a lineage-tracing strategy, we specifically labeled fetal-derived Cdx2 cells with enhanced green fluorescent protein (eGFP). Cdx2-eGFP cells from end-gestation placenta were assayed for cardiac differentiation in vitro and in vivo using a mouse model of myocardial infarction. We observed that these cells differentiated into spontaneously beating cardiomyocytes (CMs) and vascular cells in vitro, indicating multipotentiality. When administered via tail vein to infarcted wild-type male mice, they selectively and robustly homed to the heart and differentiated to CMs and blood vessels, resulting in significant improvement in contractility as noted by MRI. Proteomics and immune transcriptomics studies of Cdx2-eGFP cells compared with embryonic stem (ES) cells reveal that they appear to retain “stem”-related functions of ES cells but exhibit unique signatures supporting roles in homing and survival, with an ability to evade immune surveillance, which is critical for cell-based therapy. Cdx2-eGFP cells may potentially represent a therapeutic advance in allogeneic cell therapy for cardiac repair.

230 GENERATION OF PUTATIVE RABBIT EMBRYONIC STEM CELLS

2007 ◽  
Vol 19 (1) ◽  
pp. 231
Author(s):  
S. Wang ◽  
X. Tang ◽  
Y. Niu ◽  
H. Chen ◽  
T. Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
High Speed ◽  
Es Cells ◽  
Research Work ◽  
Embryonic Stem ◽  
Morphological Characteristics ◽  
Mouse Escs

The rabbit, as a laboratory animal model, has several advantages in the study of human physiological disorders. In this study, stable putative pluripotent rabbit embryonic stem cells (rESCs) were derived from in vivo-fertilized and in vitro-cultured blastocysts. The rabbit ICMs were obtained by 0.05% trypsin–0.008% EDTA treatment and mechanical separation; the ES-like cell colonies seen several days later. ICM-derived outgrowths which were treated with 5 mg/mL-1 dispase, followed by 0.05% trypsin–0.008% EDTA, were mechanically disaggregated into small clumps and reseeded on MEFs. The putative ES cell lines maintained expression of pluripotent cells markers and normal XY karyotype for long periods of culture (>1 month). The putative rESCs expressed alkaline phosphatase, transcription factor Oct-4, stage-specific embryonic antigens (SSEA-1, SSEA-3, and SSEA-4), and tumor-related antigens (TRA-1-60 and TRA-1-81). The morphological characteristics of the putative ESCs are closer to those of human ESCs; their high speed of proliferation, however, is closer to that of mouse ESCs. Putative rabbit ESCs were induced to differentiate into many cell types including trophoblast cells, similar to primate ESCs, in vitro, and formed teratomas with derivatives of the 3 major germ layers in vivo when injected into SCID mice. Using RT-PCR measurement, but with some differences in ligands and inhibitors, and comparing with human and mouse ESCs, the putative rabbit ESCs expressed similar genes related to pluripotency (Oct-4, Nanog, SOX2, and UTF-1) and similar genes of FGF, WNT, and TGF signaling pathways related to the proliferation and self-renewal. Our further research work showed that TGF beta and FGF pathways cooperate to maintain pluripotency of rabbit ESCs similar to those of human ES cells.

282 IMPROVED QUALITY OF PORCINE BLASTOCYSTS BY AGGREGATION OF EMBRYOS AT THE 4 - 8-CELL STAGE

2006 ◽  
Vol 18 (2) ◽  
pp. 248
Author(s):  
S.-G. Lee ◽  
C.-H. Park ◽  
D.-H. Choi ◽  
H.-Y. Son ◽  
C.-K. Lee
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
Transgenic Animals ◽  
Cell Number ◽  
Blastocyst Stage ◽  
Cell Stage ◽  
Vitro Fertilization

Use of blastocysts produced in vitro would be an efficient way to generate embryonic stem (ES) cells for the production of transgenic animals and the study of developmental gene regulation. In pigs, the morphology and cell number of in vitro-produced blastocysts are inferior to these parameters in their in vivo counterparts. Therefore, establishment of ES cells from blastocysts produced in vitro might be hindered by poor embryo quality. The objective of this study was to increase the cell number of blastocysts derived by aggregating 4–8-cell stage porcine embryos produced in vitro. Cumulus–oocyte complexes were collected from prepubertal gilt ovaries, and matured in vitro. Embryos at the 4–8-cell stage were produced by culturing embryos for two days after in vitro fertilization (IVF). After removal of the zona pellucida with acid Tyrode’s solution, one (1X), two (2X), and three (3X) 4–8-cell stage embryos were aggregated by co-culturing them in aggregation plates followed by culturing to the blastocyst stage. After 7 days, the developmental ability and the number of cells in aggregated embryos were determined by staining with Hoechst 33342 and propidium iodide. The percentage of blastocysts was higher in both 2X and 3X aggregated embryos compared to that of 1X and that of intact controls (Table 1). The cell number of blastocysts also increased in aggregated embryos compared to that of non-aggregated (1X) embryos and controls. This result suggests that aggregation might improve the quality of in vitro-fertilized porcine blastocysts by increasing cell numbers, thus becoming a useful resource for isolation and establishment of porcine ES cells. Further studies are required to investigate the quality of the aggregated embryos in terms of increasing the pluripotent cell population by staining for Oct-4 and to apply improved aggregation methods in nuclear-transferred (NT) porcine embryos. Table 1. Development, cell number, and ICM ratio of aggregated porcine embryos

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