scholarly journals DNA Methyltransferase Is Actively Retained in the Cytoplasm during Early Development

1999 ◽  
Vol 147 (1) ◽  
pp. 25-32 ◽  
Author(s):  
M. Cristina Cardoso ◽  
Heinrich Leonhardt
Keyword(s):  
Early Development ◽  
Nuclear Localization ◽  
Dna Methyltransferase ◽  
Blastocyst Stage ◽  
Mammalian Development ◽  
Nuclear Localization Signals ◽  
Early Embryos ◽  
Necessary And Sufficient ◽  
Early Mammalian Development ◽  
Dna Substrate

The overall DNA methylation level sharply decreases from the zygote to the blastocyst stage despite the presence of high levels of DNA methyltransferase (Dnmt1). Surprisingly, the enzyme is localized in the cytoplasm of early embryos despite the presence of several functional nuclear localization signals. We mapped a region in the NH2-terminal, regulatory domain of Dnmt1 that is necessary and sufficient for cytoplasmic retention during early development. Altogether, our results suggest that Dnmt1 is actively retained in the cytoplasm, which prevents binding to its DNA substrate in the nucleus and thereby contributes to the erasure of gamete-specific epigenetic information during early mammalian development.

Differential mRNA expression of the phosphoprotein p19/SCG10 gene family in mouse preimplantation embryos, uterus, and placenta

1992 ◽  
Vol 4 (2) ◽  
pp. 205 ◽  
Author(s):  
S Pampfer ◽  
W Fan ◽  
UK Schubart ◽  
JW Pollard
Keyword(s):  
Gene Family ◽  
Mammalian Cells ◽  
Developmental Stages ◽  
Blastocyst Stage ◽  
Northern Blotting ◽  
Preimplantation Embryos ◽  
Mammalian Development ◽  
Specific Expression ◽  
Developing Neurons ◽  
Early Mammalian Development

The p19/SCG10 gene family encodes two structurally related cellular proteins that are implicated in signal transduction during differentiation of mammalian cells. Previous evidence suggests that both genes are expressed in a stage-specific manner but that expression of p19 is widespread, whereas that of SCG10 is restricted to developing neurons. To determine at which developmental stage these two genes are first expressed, we have probed for mRNA transcripts in preimplantation embryos and the utero-placental unit of the mouse. As determined by polymerase chain reaction (PCR) to amplify reverse-transcribed RNA, expression of both genes was detected in preimplantation embryos, although the temporal pattern was distinct. p19 mRNA appeared transiently in 2-cell embryos, was undetectable in morulae and early blastocysts and reappeared in expanded blastocysts. In contrast, embryonic expression of SCG10 mRNA commenced in morulae and was maintained through to the blastocyst stage. Interestingly, only SCG10 expression could be detected in blastocysts derived from cultures of 2-cell embryos. During the post-implantation period, SCG10 transcripts were only detected in the uterus and placenta by reverse transcriptase-PCR, whereas p19 mRNA could be detected by Northern blotting and showed stage-specific expression in both tissues. The data confirm that, at later developmental stages, expression of p19 is widespread while that of SCG10 is more restricted. The expression of both genes in preimplantation embryos suggests distinct but possibly overlapping roles for p19 and SCG10 in early mammalian development.

scholarly journals The Influence of Interspecies Somatic Cell Nuclear Transfer on Epigenetic Enzymes Transcription in Early Embryos

2016 ◽  
Vol 39 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Martin Morovic ◽  
Matej Murin ◽  
Frantisek Strejcek ◽  
Michal Benc ◽  
Dusan Paál ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Coming Out ◽  
Somatic Cell Nuclear Transfer ◽  
Nuclear Transfer ◽  
Dna Methyltransferase ◽  
Dna Methyltransferases ◽  
Preimplantation Embryos ◽  
Mammalian Development ◽  
Cell Stage ◽  
Early Embryos

AbstractOne of the main reason for the incorrect development of embryos derived from somatic cell nuclear transfer is caused by insufficient demethylation of injected somatic chromatin to a state comparable with an early embryonic nucleus. It is already known that the epigenetic enzymes transcription in oocytes and early embryos of several species including bovine and porcine zygotes is species-dependent process and the incomplete DNA methylation correlates with the nuclear transfer failure rate in mammals. In this study the transcription of DNA methyltransferase 1 and 3a (DNMT1, DNMT3a) genes in early embryonic stages of interspecies (bovine, porcine) nuclear transfer embryos (iSCNT) by RT-PCR were analyzed. Coming out from the diverse timing of embryonic genome activation (EGA) in porcine and bovine preimplantation embryos, the intense effect of ooplasm on transferred somatic cell nucleus was expected. In spite of the detection of ooplasmic DNA methyltransferases, the somatic genes for DNMT1 and DNMT3a enzymes were not expressed and the development of intergeneric embryos stopped at the 4-cell stage. Our results indicate that the epigenetic reprogramming during early mammalian development is strongly influenced by the ooplasmic environment.

scholarly journals Heterochromatin Morphodynamics in Late Oogenesis and Early Embryogenesis of Mammals

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1497 ◽  
Author(s):  
Irina Bogolyubova ◽  
Dmitry Bogolyubov
Keyword(s):  
Molecular Mechanisms ◽  
Chromatin Condensation ◽  
Mammalian Species ◽  
Biological Significance ◽  
Histone Variants ◽  
Nuclear Bodies ◽  
Mammalian Development ◽  
Oocyte Growth ◽  
Early Embryos ◽  
Early Mammalian Development

During the period of oocyte growth, chromatin undergoes global rearrangements at both morphological and molecular levels. An intriguing feature of oogenesis in some mammalian species is the formation of a heterochromatin ring-shaped structure, called the karyosphere or surrounded “nucleolus”, which is associated with the periphery of the nucleolus-like bodies (NLBs). Morphologically similar heterochromatin structures also form around the nucleolus-precursor bodies (NPBs) in zygotes and persist for several first cleavage divisions in blastomeres. Despite recent progress in our understanding the regulation of gene silencing/expression during early mammalian development, as well as the molecular mechanisms that underlie chromatin condensation and heterochromatin structure, the biological significance of the karyosphere and its counterparts in early embryos is still elusive. We pay attention to both the changes of heterochromatin morphology and to the molecular mechanisms that can affect the configuration and functional activity of chromatin. We briefly discuss how DNA methylation, post-translational histone modifications, alternative histone variants, and some chromatin-associated non-histone proteins may be involved in the formation of peculiar heterochromatin structures intimately associated with NLBs and NPBs, the unique nuclear bodies of oocytes and early embryos.

scholarly journals Drosophila Enhancer of Rudimentary Homolog, ERH, Is a Binding Partner of RPS3, RPL19, and DDIT4, Suggesting a Mechanism for the Nuclear Localization of ERH

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Stuart I. Tsubota ◽  
Anthony C. Phillips
Keyword(s):  
Amino Acid ◽  
Nuclear Localization ◽  
Cellular Proliferation ◽  
Notch Signaling Pathway ◽  
Nuclear Localization Signals ◽  
Amino Acid Region ◽  
Binding Partners ◽  
Enhancer Of Rudimentary ◽  
Necessary And Sufficient ◽  
Acid Region

The protein enhancer of rudimentary homolog, ERH, is a small, highly conserved protein that has been found in animals, plants, and protists. Genetic and biochemical interactions have implicated ERH in the regulation of pyrimidine biosynthesis, DNA replication, transcription, mRNA splicing, cellular proliferation, tumorigenesis, and the Notch signaling pathway. In vertebrates and insects, ERH is nuclearly localized; however, an examination of the ERH amino-acid sequence does not reveal any nuclear localization signals. In this paper we show that the first 24 amino acids contain sequences necessary and sufficient for nuclear localization. Through yeast two-hybrid screens, three new binding partners of ERH, RPS3, RPL19, and DDIT4, were identified. RPS3 was isolated from both human and Drosophila screens. These interactions suggest functions of ERH in cell growth, cancer, and DNA repair. The ERH sequences necessary for the interactions between ERH and RPS3 and RPL19 are mapped onto the same 24-amino-acid region in ERH which are necessary for nuclear localization, suggesting that ERH is localizing to the nucleus through binding to one of its DNA-binding partners, such as RPS3 or RPL19.

scholarly journals Aggregation recovers developmental plasticity in mouse polyploid embryos

2019 ◽  
Vol 31 (2) ◽  
pp. 404 ◽  
Author(s):  
Hiroyuki Imai ◽  
Wataru Fujii ◽  
Ken Takeshi Kusakabe ◽  
Yasuo Kiso ◽  
Kiyoshi Kano
Keyword(s):  
Mammalian Cells ◽  
Developmental Plasticity ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Embryonic Stem ◽  
Blastocyst Stage ◽  
Mammalian Development ◽  
Cellular Functions ◽  
Developmental Potential ◽  
Early Mammalian Development

Tetraploid embryos normally develop into blastocysts and embryonic stem cells can be established from tetraploid blastocysts in mice. Thus, polyploidisation does not seem to be so harmful during preimplantation development. However, the mechanisms by which early mammalian development accepts polyploidisation are poorly understood. In this study, we aimed to elucidate the effect of polyploidisation on early mammalian development and to further comprehend its tolerance using hyperpolyploid embryos produced by repetitive whole genome duplication. We successfully established several types of polyploid embryos (tetraploid, octaploid and hexadecaploid) and studied their developmental potential invitro. We demonstrated that all types of these polyploid embryos maintained the ability to develop to the blastocyst stage, which implies that mammalian cells might have basic cellular functions in implanted embryos, despite polyploidisation. However, the inner cell mass was absent in hexadecaploid blastocysts. To complement the total number of cells in blastocysts, a fused hexadecaploid embryo was produced by aggregating several hexadecaploid embryos. The results indicated that the fused hexadecaploid embryo finally recovered pluripotent cells in the blastocyst. Thus, our findings suggest that early mammalian embryos may have the tolerance and higher plasticity to adapt to hyperpolyploidisation for blastocyst formation, despite intense alteration of the genome volume.

scholarly journals The N-terminus of fission yeast DNA polymerase alpha contains a basic pentapeptide that acts in vivo as a nuclear localization signal.

1995 ◽  
Vol 6 (12) ◽  
pp. 1697-1705 ◽  
Author(s):  
D Bouvier ◽  
G Baldacci
Keyword(s):  
Fission Yeast ◽  
Dna Polymerase ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Terminal Sequence ◽  
Nuclear Localization Signals ◽  
Dna Polymerase Alpha ◽  
Localization Signal ◽  
Necessary And Sufficient

The N-terminal sequence of the catalytic subunit of fission yeast DNA polymerase alpha (pol alpha) contains two putative nuclear localization signals (NLS). To check the functionality of these signals in vivo, the N-terminal sequence was experimentally divided into three amino acid blocks, two of which contain a distinct presumptive NLS. Each block was deleted, either individually or in combination with one of the two others. The deleted gene products were expressed in fission yeast, and assayed by indirect immunofluorescence for their aptitude to localize to the cell nucleus. Block II, which contains the putative NLS pentapeptide 97RKRKK, was both necessary and sufficient to promote nuclear import of pol alpha, as well as of a pyruvate kinase fusion protein. Precise excision of the NLS pentapeptide from block II inhibited the nuclear import of pol alpha, thus confirming the role of this sequence as the functional NLS of the fission yeast enzyme.

scholarly journals Recent evolution of a TET-controlled and DPPA3/STELLA-driven pathway of passive demethylation in mammals

2018 ◽  
Author(s):  
Christopher B. Mulholland ◽  
Atsuya Nishiyama ◽  
Joel Ryan ◽  
Ryohei Nakamura ◽  
Merve Yiğit ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Ectopic Expression ◽  
Dna Demethylation ◽  
Mammalian Development ◽  
Dna Hypomethylation ◽  
Tet Proteins ◽  
Genome Wide ◽  
Recent Emergence ◽  
High Conservation ◽  
Early Mammalian Development

AbstractGenome-wide DNA demethylation is a unique feature of mammalian development and naïve pluripotent stem cells. So far, it was unclear how mammals specifically achieve global DNA hypomethylation, given the high conservation of the DNA (de-)methylation machinery among vertebrates. We found that DNA demethylation requires TET activity but mostly occurs at sites where TET proteins are not bound suggesting a rather indirect mechanism. Among the few specific genes bound and activated by TET proteins was the naïve pluripotency and germline marker Dppa3 (Pgc7, Stella), which undergoes TDG dependent demethylation. The requirement of TET proteins for genome-wide DNA demethylation could be bypassed by ectopic expression of Dppa3. We show that DPPA3 binds and displaces UHRF1 from chromatin and thereby prevents the recruitment and activation of the maintenance DNA methyltransferase DNMT1. We demonstrate that DPPA3 alone can drive global DNA demethylation when transferred to amphibians (Xenopus) and fish (medaka), both species that naturally do not have a Dppa3 gene and exhibit no post-fertilization DNA demethylation. Our results show that TET proteins are responsible for active and - indirectly also for - passive DNA demethylation; while TET proteins initiate local and gene-specific demethylation in vertebrates, the recent emergence of DPPA3 introduced a unique means of genome-wide passive demethylation in mammals and contributed to the evolution of epigenetic regulation during early mammalian development.

scholarly journals Research on early mammalian development in India

2020 ◽  
Vol 64 (1-2-3) ◽  
pp. 109-121
Author(s):  
Polani B. Seshagiri ◽  
Venkatappa Vani
Keyword(s):  
Developmental Biology ◽  
Early Development ◽  
Assisted Reproductive Technologies ◽  
Reproductive Technologies ◽  
Current Status ◽  
Infrastructure Development ◽  
Mammalian Development ◽  
Indian Government ◽  
The Usa ◽  
Early Mammalian Development

Historically, research in India on early mammalian development had only begun, rather modestly, in the last century, unlike the USA and UK. In India, initial studies were on gonadal and reproductive tissue development and function and they were limited to anatomical and histological characterization. This was followed by research on fertility regulation and contraception. Since the 1960s, a major initiative took place regarding endocrine biochemistry and the use of antifertility agents in inhibiting gonadal function and early development. Post-independence, the Indian government´s funding support enabled universities and institutions to embark on various research disciplines in biology but with no particular emphasis on developmental biology per se. Subsequently, India made significant progress in the area of mammalian reproduction and development, but not specifically in the core aspects of developmental biology. Reasons for this could be due to the nation’s compulsion to invest and embark on socio-economic and infrastructure development and on research involving family planning methods for reversible-affordable contraceptives to curtail population growth. With regard to the latter, biologists were involved in hormone-based contraception research. During this pursuit, insights were achieved into basic aspects of the development of gonads, gametes and embryos. Notwithstanding this, in the post-1980s through to the present time, Indian scientists have contributed to (i) the understanding of the cellular and molecular regulation of early development, (ii) developing genetically modified mouse models, (iii) using assisted reproductive technologies, generating mammalian progeny, including humans and (iv) deriving pluripotent stem cell lines for developmental studies. This article provides a perspective on the past and current status of early mammalian development research in India.

scholarly journals Aggregation recovers developmental plasticity in mouse polyploid embryos

2018 ◽  
Author(s):  
Hiroyuki Imai ◽  
Wataru Fujii ◽  
Ken Takeshi Kusakabe ◽  
Yasuo Kiso ◽  
Kiyoshi Kano
Keyword(s):  
Mammalian Cells ◽  
Developmental Plasticity ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Embryonic Stem ◽  
Blastocyst Stage ◽  
Mammalian Development ◽  
Developmental Potential ◽  
Early Mammalian Development

ABSTRACTPolyploidy is comparatively prevalent in amphibians and fishes, but is infrequent in animals because of lethality after implantation. On the contrary, tetraploid embryos normally develop into blastocysts, and embryonic stem cells can be established from tetraploid blastocysts in mice. Thus, polyploidization does not seem to be so harmful during preimplantation development. However, the mechanisms by which early mammalian development accepts polyploidization are still poorly understood. In this study, we aimed to elucidate the effect of polyploidization on early mammalian development and to further comprehend its tolerability using hyperpolyploid embryos produced by artificial, repetitive whole genome duplication. Therefore, we successfully established several types of polyploid embryos (tetraploid, octaploid, and hexadecaploid), produced using repeated electrofusion of two-cell embryos in mice, and studied their developmental potential in vitro. We demonstrated that all types of these polyploid embryos maintained the ability to develop to the blastocyst stage, which implies that mammalian cells might have basic cellular functions in implanted embryos, despite polyploidization. However, the inner cell mass was absent in the hexadecaploid blastocysts. To complement the total cells in blastocysts, a fused hexadecaploid embryo was produced by aggregating a number of hexadecaploid embryos. The results indicated that the fused hexadecaploid embryo finally recovered pluripotent cells in blastocysts. Thus, our findings suggested that early mammalian embryos may have the tolerability and higher plasticity to adapt to hyperpolyploidization for blastocyst formation, despite intense alteration of the genome volume.

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