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Shiokawa K, Aso M, Kondo T, Uchiyama H, Kuroyanagi S, Takai JI, Takahashi S, Kajitani M, Kaito C, Sekimizu K, Takayama E, Igarashi K, Hara H. Gene expression in Pre-MBT embryos and activation of maternally-inherited program of apoptosis to be executed at around MBT as a fail-safe mechanism in Xenopus early embryogenesis. GENE REGULATION AND SYSTEMS BIOLOGY 2008; 2:213-31. [PMID: 19787085 PMCID: PMC2733083 DOI: 10.4137/grsb.s579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
S-adenosylmethionine decarboxylase (SAMDC) is an enzyme which converts S-adenosylmethione (SAM), a methyl donor, to decarboxylated SAM (dcSAM), an aminopropyl donor for polyamine biosynthesis. In our studies on gene expression control in Xenopus early embryogenesis, we cloned the mRNA for Xenopus SAMDC, and overexpressed the enzyme by microinjecting its mRNA into Xenopus fertilized eggs. In the mRNA-injected embryos, the level of SAMDC was enormously increased, the SAM was exhausted, and protein synthesis was greatly inhibited, but cellular polyamine content did not change appreciably. SAMDC-overexpressed embryos cleaved and developed normally up to the early blastula stage, but at the midblastula stage, or the stage of midblastula transition (MBT), all the embryos were dissociated into cells, and destroyed due to execution of apoptosis. During cleavage SAMDC-overexpressed embryos transcribed caspase-8 gene, and this was followed by activation of caspase-9. When we overexpressed p53 mRNA in fertilized eggs, similar apoptosis took place at MBT, but in this case, transcription of caspase-8 did not occur, however activation of caspase-9 took place. Apoptosis induced by SAMDC-overexpression was completely suppressed by Bcl-2, whereas apoptosis induced by p53 overexpression or treatments with other toxic agents was only partially rescued. When we injected SAMDC mRNA into only one blastomere of 8- to 32-celled embryos, descendant cells of the mRNA-injected blastomere were segregated into the blastocoel and underwent apoptosis within the blastocoel, although such embryos continued to develop and became tadpoles with various extents of anomaly, reflecting the developmental fate of the eliminated cells. Thus, embryonic cells appear to check themselves at MBT and if physiologically severely-damaged cells occur, they are eliminated from the embryo by activation and execution of the maternally-inherited program of apoptosis. We assume that the apoptosis executed at MBT is a "fail-safe" mechanism of early development to save the embryo from accidental damages that take place during cleavage.
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Affiliation(s)
- Koichiro Shiokawa
- Department of Biosciences, School of Science and Engineering, Teikyo University; 1-1 Toyosatodai, Utsunomiya, Tochigi Prefecture 320-8551, Japan.
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Lawinger P, Rastelli L, Zhao Z, Majumder S. Lack of enhancer function in mammals is unique to oocytes and fertilized eggs. J Biol Chem 1999; 274:8002-11. [PMID: 10075699 DOI: 10.1074/jbc.274.12.8002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies have shown that the lack of novel coactivator activity in mouse oocytes and one-cell embryos (fertilized eggs) renders them incapable of utilizing Gal4:VP16-dependent enhancers (distal elements) but not promoters (proximal elements) in regulating transcription. This coactivator activity first appears in two- to four-cell embryos coincident with the major activation of zygotic gene expression. Here we show that whereas oocytes and fertilized eggs could utilize Sp1-dependent promoters, they could not utilize Sp1-dependent enhancers, although they showed promoter repression, which is a requirement for delineating enhancer function. In contrast, both Sp1-dependent promoters and enhancers were functional in two- to four-cell embryos. Furthermore, the same embryonic stem cell mRNA that provided the coactivator activity for Gal4:VP16-dependent enhancer function also provided Sp1-dependent enhancer function in oocytes. Therefore, the coactivator activity appears to be a requirement for general enhancer function. To determine whether the absence of enhancer function is a unique property of oocytes or a general property of other terminally differentiated cells, transcription was examined in terminally differentiated hNT neurons and their precursors, undifferentiated NT2 stem cells. The results showed that both cell types could utilize enhancers and promoters. Thus, in mammals, the lack of enhancer function appears to be unique to oocytes and fertilized eggs, suggesting that it provides a safeguard against premature activation of genes prior to zygotic gene expression during development.
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Affiliation(s)
- P Lawinger
- University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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Lefresne J, Andéol Y, Signoret J. Evidence for introduction of a variable G1 phase at the midblastula transition during early development in axolotl. Dev Growth Differ 1998; 40:497-508. [PMID: 9783475 DOI: 10.1046/j.1440-169x.1998.t01-3-00004.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
After fertilization in axolotl, the synchronous cell cleavages are triphasic (S, G2 and M phases). Midblastula transition (MBT) begins at the ninth cleavage and is the consequence of lengthening of cell cycles. By spectrofluorometry and incorporation of 3H thymidine into the nuclear DNA followed by autoradiography on individual cells, the time at which a G1 phase appears during early development was investigated. The present results show that the G1 phase was introduced for the first time at MBT and its duration was variable from one blastomere to another. This variability could account for lengthening of cell cycles and be required for zygotic transcriptions necessary for DNA replication. From this point of view, axolotl represents an interesting alternative amphibian model to identify regulators involved in the G1-S transition at MBT during early development.
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Affiliation(s)
- J Lefresne
- Laboratoire d'Oncologie Cellulaire et Toxicologie Génétique, Centre Anti-Cancéreux François Baclesse, Université de Caen, France
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Isolation of Xenopus HGF gene promoter and its functional analysis in embryos and animal caps. Dev Genes Evol 1996; 205:300-310. [PMID: 28306033 DOI: 10.1007/bf00365808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/1995] [Accepted: 08/22/1995] [Indexed: 10/26/2022]
Abstract
Previously, we isolated Xenopus HGF (hepatocyte growth factor) cDNA and showed in Xenopus embryos that expression of this gene starts at the late gastrula stage mainly in the ventral mesoderm, and furthermore that the expression is induced in animal cap by activin A and bFGF (basic fibroblast growth factor). Here we have cloned the Xenopus HGF gene, covering a 14 kb 5'-upstream region and a 0.2 kb 5'-coding region. Within about 0.5 kb of the 5'-flanking region, the Xenopus HGF gene contained a TATA-like element AATGAAA, one putative NF-1 binding site, two NF-IL-6 binding motif sequences, one putative TGF-β-dependent inhibitory element (TIE) and one AP-1 binding site. A recombinant circular plasmid consisting of a 1.7 kb HGF promoter region and the bacterial chloramphenicol acetyltransferase (CAT) gene was first expressed at the late gastrula stage in the ventral mesoderm, as was the endogenous HGF gene. The expression of the fusion gene was induced in animal cap cells by activin A and bFGF although induction by the latter was not so strong. Using a series of 5'-deletion constructs introduced into animal caps, silencer elements, which seem to be essential for the gene's regionally correct expression, and the element responsible for induction by activin were found. The results show that the HGF gene promoter isolated here contains elements which may endow the gene with the regulative function for its temporally and spatially regulated expression, although the element necessary for induction by bFGF seems to be missing.
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Majumder S, DePamphilis ML. A unique role for enhancers is revealed during early mouse development. Bioessays 1995; 17:879-89. [PMID: 7487969 DOI: 10.1002/bies.950171010] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Transcription and replication of genes in mammalian cells always requires a promoter or replication origin, respectively, but the ability of enhancers to stimulate these regulatory elements and the interactions that mediate this stimulation are developmentally acquired. The primary function of enhancers is to prevent repression, which appears to result from particular components of chromatin structure. Factors responsible for this repression are present in the maternal nucleus of oocytes and its descendant, the maternal pronucleus of mouse 1-cell embryos and in mouse 2-cell embryos, but are absent in the paternal pronucleus. Thus, enhancers are not needed to achieve efficient transcription and replication in paternal pronuclei. However, enhancers, even in the presence of their specific activation protein, are inactive prior to formation of a 2-cell embryo, suggesting that a coactivator essential for enhancer function is not available until zygotic gene expression begins. Furthermore, enhancer stimulation of transcription appears to be mediated through a promoter transcription factor, but this interaction can change as cells undergo differentiation, switching from a TATA-box independent to a TATA-box dependent mode.
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Affiliation(s)
- S Majumder
- Roche Institute of Molecular Biology, Roche Research Center, Nutley, New Jersey 07110-1199, USA
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Majumder S, DePamphilis ML. Requirements for DNA transcription and replication at the beginning of mouse development. J Cell Biochem 1994; 55:59-68. [PMID: 8083300 DOI: 10.1002/jcb.240550107] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In mice, the first round of DNA replication occurs in fertilized eggs (1-cell embryos), while the onset of zygotic gene transcription begins approximately 20 hours after fertilization, a time that normally coincides with formation of a 2-cell embryo. One approach to investigating the mechanisms that control these developmentally regulated events has been to microinject plasmid DNA into the nuclei of mouse oocytes and embryos in order to determine the requirements for unique DNA sequences that regulate transcription and replication. The results from these and other studies have revealed two important mechanisms that regulate the beginning of animal development. The first is a time dependent "zygotic clock" of unknown detail that delays the onset of transcription, regardless of whether or not a 2-cell embryo is formed. The second is a mechanism that represses the activity of promoters and origins of replication specifically in maternal pronuclei of oocytes and 1-cell embryos, and in all nuclei of 2-cell embryos, regardless of their parental origin or ploidy. This repression is linked to chromatin, but the striking ability to relieve this repression with specific embryo-responsive enhancers first appears with formation of a 2-cell embryo. The need for a TATA-box to mediate enhancer stimulation of promoter activity appears even later when cell differentiation becomes evident. Thus, a biological clock delays transcription until both paternal and maternal genomes are replicated and remodeled from a post-meiotic state to one in which transcription is repressed by chromatin structure in a manner that can be relieved by cell-specific enhancers at appropriate times during development.
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Affiliation(s)
- S Majumder
- Roche Institute of Molecular Biology, Roche Research Center, Nutley, New Jersey 07110
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And�ol Y. Early transcription in different animal species: implication for transition from maternal to zygotic control in development. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf00744867] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hikosaka A, Kusakabe T, Satoh N, Makabe KW. Introduction and Expression of Recombinant Genes in Ascidian Embryos. Dev Growth Differ 1992. [DOI: 10.1111/j.1440-169x.1992.tb00031.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Isolation and characterization of a Xenopus cDNA which encodes a homeodomain highly homologous to Drosophila Distal-less. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42726-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Kondo M, Tashiro K, Fujii G, Asano M, Miyoshi R, Yamada R, Muramatsu M, Shiokawa K. Activin receptor mRNA is expressed early in Xenopus embryogenesis and the level of the expression affects the body axis formation. Biochem Biophys Res Commun 1991; 181:684-90. [PMID: 1661587 DOI: 10.1016/0006-291x(91)91245-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Activin is a member of the transforming growth factor beta (TGF-beta) and possesses various activities in cellular control phenomena. During Xenopus embryonic development, activin is thought to act as a natural mesoderm-inducing factor. We isolated here the Xenopus activin receptor cDNA from Xenopus tadpole cDNA library and examined the expression of the Xenopus activin receptor gene during the course of early embryonic development. The Xenopus activin receptor has an 87% homology at the level of deduced amino acid sequence with the mouse activin receptor, and using the cDNA obtained, three bands of mRNA with different lengths were detected in Xenopus embryos throughout early embryogenesis. We synthesized activin receptor mRNA in vitro and tested the effect of the injection of the mRNA into Xenopus fertilized eggs on subsequent development. When the synthetic mRNA was injected into uncleaved fertilized eggs, embryos with reduced trunk structure were formed. However, when the mRNA was injected into the ventral blastomeres at the 16-cell stage, embryos with a secondary body axis were formed. These results indicate the importance of the function of activin receptor in the regulatory mechanism for body axis formation.
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Affiliation(s)
- M Kondo
- Laboratory of Molecular Embryology, Faculty of Science, University of Tokyo, Japan
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Wiekowski M, Miranda M, DePamphilis ML. Regulation of gene expression in preimplantation mouse embryos: effects of the zygotic clock and the first mitosis on promoter and enhancer activities. Dev Biol 1991; 147:403-14. [PMID: 1916016 DOI: 10.1016/0012-1606(91)90298-h] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Previous studies have reported that promoters requiring enhancers for full activity in mammalian somatic cells also require enhancers when injected into mouse two-cell embryos, whereas the same promoters can be expressed just as efficiently in the absence of an enhancer when injected into arrested one-cell embryos. Experiments were designed to determine whether this phenomenon reflected normal developmental changes at the beginning of mammalian development, or simply differences in the physiological states of these cells under the experimental conditions employed. The activity of three different promoters that function in a wide variety of mammalian cells was measured both in embryos whose morphological development was arrested and in embryos that continued development in vitro. Expression of the injected gene was related to the onset of zygotic gene expression ("zygotic clock"), the phase of the cell proliferation cycle, the use of aphidicolin to arrest cell proliferation, and formation of two-cell embryos in vitro and in vivo. The results demonstrated that promoter activity was tightly linked to zygotic gene expression, while the need for enhancers to stimulate promoter activity depended only on formation of a two-cell embryo. These results further support the hypothesis that the first mitosis induces a general repression of promoters prior to initiation of zygotic gene expression that is relieved specifically by enhancers.
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Affiliation(s)
- M Wiekowski
- Department of Cell and Developmental Biology, Roche Institute of Molecular Biology, Nutley, New Jersey 07110
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Shiokawa K. Gene Expression from Endogenou and Exogenously-introduced DNAs in Early Embryogenesis of Xenopus laevis. (Xenopus embryogenesis/nuclear RNA synthesis/midblastula transition/CAT gene injection/actin-CAT fusion gene). Dev Growth Differ 1991. [DOI: 10.1111/j.1440-169x.1991.00001.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Tashiro K, Yamada R, Asano M, Hashimoto M, Muramatsu M, Shiokawa K. Expression of mRNA for activin-binding protein (follistatin) during early embryonic development of Xenopus laevis. Biochem Biophys Res Commun 1991; 174:1022-7. [PMID: 1704219 DOI: 10.1016/0006-291x(91)91521-d] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Follistatin is a specific activin-binding protein and is supposed to control activin functions. During Xenopus embryonic development, activin is thought to act as a natural mesoderm-inducing factor. We isolated here the Xenopus follistatin cDNA from Xenopus ovary cDNA library and studied the expression of Xenopus follistatin gene during the course of early embryonic development. The Xenopus follistatin has an 84% homology at the level of deduced amino acid sequence with human and porcine follistatin. Its 3.5 kb mRNA is first expressed at the gastrula stage, when the expression of activin mRNA becomes first detectable, and increased thereafter. Another species of 2 kb mRNA become detectable from early neurula and also increased dramatically in tadpole. These results suggest that the follistatin acts also as a regulator of activin in inductive interactions during amphibian embryonic development.
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Affiliation(s)
- K Tashiro
- Laboratory of Molecular Embryology, Faculty of Science, University of Tokyo, Japan
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Perry M, Morrice D, Hettle S, Sang H. Expression of exogenous DNA during the early development of the chick embryo. ACTA ACUST UNITED AC 1991; 200:312-319. [DOI: 10.1007/bf00665526] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/1991] [Accepted: 07/15/1991] [Indexed: 10/26/2022]
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Temporally uncontrolled expression of linearized plasmid DNA which carries bacterial chloramphenicol acetyltransferase gene withXenopus cardiacα-actin promoter after injection intoXenopus fertilized eggs. ACTA ACUST UNITED AC 1990; 199:174-180. [DOI: 10.1007/bf01681491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/1990] [Accepted: 08/06/1990] [Indexed: 10/25/2022]
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