scholarly journals Endogenous Retroviruses Function as Gene Expression Regulatory Elements During Mammalian Pre-implantation Embryo Development

2019 ◽  
Vol 20 (3) ◽  
pp. 790 ◽  
Author(s):  
Bo Fu ◽  
Hong Ma ◽  
Di Liu
Keyword(s):  
Gene Expression ◽  
Embryo Development ◽  
Transcriptional Activation ◽  
Nuclear Transfer ◽  
Regulatory Elements ◽  
Endogenous Retroviruses ◽  
Maternal Control ◽  
Close Relationship ◽  
Genome Activation ◽  
Zygotic Genome

Pre-implantation embryo development encompasses several key developmental events, especially the activation of zygotic genome activation (ZGA)-related genes. Endogenous retroviruses (ERVs), which are regarded as “deleterious genomic parasites”, were previously considered to be “junk DNA”. However, it is now known that ERVs, with limited conservatism across species, mediate conserved developmental processes (e.g., ZGA). Transcriptional activation of ERVs occurs during the transition from maternal control to zygotic genome control, signifying ZGA. ERVs are versatile participants in rewiring gene expression networks during epigenetic reprogramming. Particularly, a subtle balance exists between ERV activation and ERV repression in host–virus interplay, which leads to stage-specific ERV expression during pre-implantation embryo development. A large portion of somatic cell nuclear transfer (SCNT) embryos display developmental arrest and ZGA failure during pre-implantation embryo development. Furthermore, because of the close relationship between ERV activation and ZGA, exploring the regulatory mechanism underlying ERV activation may also shed more light on the enigma of SCNT embryo development in model animals.

scholarly journals Somatic Cell Nuclear Transfer Embryos Show Massive Dysregulation of Genes Involved in Transcription Pathway

2020 ◽  
Author(s):  
Chunshen Long ◽  
Hanshuang Li ◽  
Xinru Li ◽  
Yongchun Zuo
Keyword(s):  
Embryo Development ◽  
Nuclear Transfer ◽  
Normal Embryo ◽  
Cloning Efficiency ◽  
Rna Seq ◽  
Activation Of Transcription ◽  
Potential Association ◽  
Gene Regulatory ◽  
Genome Activation ◽  
Zygotic Genome

AbstractTranscription is the most fundamental molecular event that occurs with zygotic genome activation (ZGA) during embryo development. However, the potential association between transcription pathways and low cloning efficiency of nuclear transfer (NT) embryos remains elusive. Here, we integrated a series of RNA-seq data on NT embryos to deciphering the molecular barriers of NT embryo development. Comparative transcriptome analysis indicated that incomplete activation of transcription pathways functions as a barrier for NT embryos. Then, the gene regulatory network (GRN) identified that crucial factors responsible for transcription play a coordinated role in epigenome erasure and pluripotency regulation during normal embryo development. But in NT embryos, massive genes involved in transcription pathways were varying degrees of inhibition. Our study therefore provides new insights into understanding the barriers to NT embryo reprogramming.

scholarly journals Transcriptional activation and repression by Fos are independent functions: the C terminus represses immediate-early gene expression via CArG elements.

1990 ◽  
Vol 10 (8) ◽  
pp. 4243-4255 ◽  
Author(s):  
D Gius ◽  
X M Cao ◽  
F J Rauscher ◽  
D R Cohen ◽  
T Curran ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Regulatory Element ◽  
Regulatory Elements ◽  
Early Gene ◽  
Immediate Early ◽  
Striking Similarity ◽  
Independent Functions

The Fos-Jun complex has been shown to activate transcription through the regulatory element known as the AP-1 binding site. We show that Fos down regulates several immediate-early genes (c-fos, Egr-1, and Egr-2) after mitogenic stimulation. Specifically, we demonstrate that the target for this repression is a sequence of the form CC(A/T)6GG, also known as a CArG box. Whereas Fos bound to the AP-1 site through a domain rich in basic amino acids and associated with Jun via a leucine zipper interaction, mutant Fos proteins lacking these structures were still capable of causing repression. Furthermore, Jun neither enhanced nor inhibited down regulation by Fos. Critical residues required for repression are located within the C-terminal 27 amino acids of c-Fos, since v-Fos and C-terminal truncations of c-Fos did not down regulate. In addition, transfer of 180 c-Fos C-terminal amino acids to Jun conferred upon it the ability to repress. Finally, Fra-1, a Fos-related protein which has striking similarity to Fos in its C-terminal 40 amino acids, also down regulated Egr-1 expression. Thus, Fos is a transcriptional regulator that can activate or repress gene expression by way of two separate functional domains that act on distinct regulatory elements.

scholarly journals Pluripotency factors select gene expression repertoire at Zygotic Genome Activation

2020 ◽  
Author(s):  
Meijiang Gao ◽  
Marina Veil ◽  
Marcus Rosenblatt ◽  
Anna Gebhard ◽  
Helge Hass ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Early Gene ◽  
Zebrafish Embryos ◽  
Fate Specification ◽  
Pluripotency Factors ◽  
Zygotic Transcription ◽  
Simultaneous Loss ◽  
Genome Activation ◽  
Zygotic Genome

AbstractAwakening of zygotic transcription in animal embryos relies on maternal pioneer transcription factors. The interplay of global and specific functions of these proteins remains poorly understood. Here, we analyzed nucleosome positioning, H3K27 acetylation, transcription, and gastrulation rates in zebrafish embryos lacking pluripotency factors Pou5f3 and Sox19b. We show that the bulk transcriptional onset does not require Sox19b and Pou5f3, but is sensitive to their balance. Pou5f3 docks H3K27ac on the enhancers of genes involved in gastrulation and ventral fate specification. Sox19b facilitates Pou5f3 access to one-third of these enhancers. The genes regulating mesendodermal and dorsal fates are primed for activation independently on Pou5f3 and Sox19b. Strikingly, the loss of either factor results in activation of silent enhancers; simultaneous loss of both leads to premature expression of differentiation genes. Our results uncover how independent activities of maternal Pou5f3 and Sox19b add up or antagonize to determine the early gene expression repertoire.

scholarly journals Inhibition of DRP1 Impedes Zygotic Genome Activation and Preimplantation Development in Mice

2021 ◽  
Vol 9 ◽  
Author(s):  
Yuanyuan Li ◽  
Ning-Hua Mei ◽  
Gui-Ping Cheng ◽  
Jing Yang ◽  
Li-Quan Zhou
Keyword(s):  
Embryo Development ◽  
Preimplantation Embryo ◽  
Preimplantation Embryos ◽  
Dependent Manner ◽  
Zygotic Genome Activation ◽  
Preimplantation Embryo Development ◽  
Cell Embryo ◽  
Embryo Stage ◽  
Genome Activation ◽  
Zygotic Genome

Mitochondrion plays an indispensable role during preimplantation embryo development. Dynamic-related protein 1 (DRP1) is critical for mitochondrial fission and controls oocyte maturation. However, its role in preimplantation embryo development is still lacking. In this study, we demonstrate that inhibition of DRP1 activity by mitochondrial division inhibitor-1, a small molecule reported to specifically inhibit DRP1 activity, can cause severe developmental arrest of preimplantation embryos in a dose-dependent manner in mice. Meanwhile, DRP1 inhibition resulted in mitochondrial dysfunction including decreased mitochondrial activity, loss of mitochondrial membrane potential, reduced mitochondrial copy number and inadequate ATP by disrupting both expression and activity of DRP1 and mitochondrial complex assembly, leading to excessive ROS production, severe DNA damage and cell cycle arrest at 2-cell embryo stage. Furthermore, reduced transcriptional and translational activity and altered histone modifications in DRP1-inhibited embryos contributed to impeded zygotic genome activation, which prevented early embryos from efficient development beyond 2-cell embryo stage. These results show that DRP1 inhibition has potential cytotoxic effects on mammalian reproduction, and DRP1 inhibitor should be used with caution when it is applied to treat diseases. Additionally, this study improves our understanding of the crosstalk between mitochondrial metabolism and zygotic genome activation.

scholarly journals HIV-1 infection activates endogenous retroviral promoters regulating antiviral gene expression

2020 ◽  
Vol 48 (19) ◽  
pp. 10890-10908
Author(s):  
Smitha Srinivasachar Badarinarayan ◽  
Irina Shcherbakova ◽  
Simon Langer ◽  
Lennart Koepke ◽  
Andrea Preising ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
Cd4 T Cells ◽  
Regulatory Elements ◽  
Human Cells ◽  
Endogenous Retroviruses ◽  
Transcription Start ◽  
Drive Gene ◽  
Antiviral Gene ◽  
Hiv 1

Abstract Although endogenous retroviruses (ERVs) are known to harbor cis-regulatory elements, their role in modulating cellular immune responses remains poorly understood. Using an RNA-seq approach, we show that several members of the ERV9 lineage, particularly LTR12C elements, are activated upon HIV-1 infection of primary CD4+ T cells. Intriguingly, HIV-1-induced ERVs harboring transcription start sites are primarily found in the vicinity of immunity genes. For example, HIV-1 infection activates LTR12C elements upstream of the interferon-inducible genes GBP2 and GBP5 that encode for broad-spectrum antiviral factors. Reporter assays demonstrated that these LTR12C elements drive gene expression in primary CD4+ T cells. In line with this, HIV-1 infection triggered the expression of a unique GBP2 transcript variant by activating a cryptic transcription start site within LTR12C. Furthermore, stimulation with HIV-1-induced cytokines increased GBP2 and GBP5 expression in human cells, but not in macaque cells that naturally lack the GBP5 gene and the LTR12C element upstream of GBP2. Finally, our findings suggest that GBP2 and GBP5 have already been active against ancient viral pathogens as they suppress the maturation of the extinct retrovirus HERV-K (HML-2). In summary, our findings uncover how human cells can exploit remnants of once-infectious retroviruses to regulate antiviral gene expression.

scholarly journals Combinatorial action of NF–Y and TALE at embryonic enhancers defines distinct gene expression programs during zygotic genome activation in zebrafish

2020 ◽  
Vol 459 (2) ◽  
pp. 161-180 ◽  
Author(s):  
William Stanney ◽  
Franck Ladam ◽  
Ian J. Donaldson ◽  
Teagan J. Parsons ◽  
René Maehr ◽  
...  
Keyword(s):  
Gene Expression ◽  
Zygotic Genome Activation ◽  
Distinct Gene ◽  
Genome Activation ◽  
Zygotic Genome

scholarly journals The control of transcriptional memory by stable mitotic bookmarking

2021 ◽  
Author(s):  
Maelle Bellec ◽  
Jeremy Dufourt ◽  
George Hunt ◽  
Helene Lenden-Hasse ◽  
Antonio Trullo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptional Activation ◽  
Expression Profiles ◽  
Large Fraction ◽  
Expression Patterns ◽  
Gene Expression Profiles ◽  
Mitotic Exit ◽  
Regulatory Sequences ◽  
Transcriptional Memory ◽  
Genome Activation

To maintain cellular identities during development, gene expression profiles must be faithfully propagated through cell generations. The reestablishment of gene expression patterns upon mitotic exit is thought to be mediated, in part, by mitotic bookmarking by transcription factors (TF). However, the mechanisms and functions of TF mitotic bookmarking during early embryogenesis remain poorly understood. In this study, taking advantage of the naturally synchronized mitoses of Drosophila early embryos, we provide evidence that the pioneer-like transcription factor GAF acts as stable mitotic bookmarker during zygotic genome activation. We report that GAF remains associated to a large fraction of its interphase targets including at cis-regulatory sequences of key developmental genes, with both active and repressive chromatin signatures. GAF mitotic targets are globally accessible during mitosis and are bookmarked via histone acetylation (H4K8ac). By monitoring the kinetics of transcriptional activation in living embryos, we provide evidence that GAF binding establishes competence for rapid activation upon mitotic exit.

scholarly journals Pleomorphic Adenoma Gene 1 Is Needed For Timely Zygotic Genome Activation and Early Embryo Development

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Elo Madissoon ◽  
Anastasios Damdimopoulos ◽  
Shintaro Katayama ◽  
Kaarel Krjutškov ◽  
Elisabet Einarsdottir ◽  
...  
Keyword(s):  
Pleomorphic Adenoma ◽  
Embryo Development ◽  
Early Embryo ◽  
Zygotic Genome Activation ◽  
Early Embryo Development ◽  
Genome Activation ◽  
Zygotic Genome

Presence of transcription regulatory elements within an intron of the virus-inducible murine TIMP gene

1988 ◽  
Vol 8 (8) ◽  
pp. 3227-3234
Author(s):  
B Coulombe ◽  
A Ponton ◽  
L Daigneault ◽  
B R Williams ◽  
D Skup
Keyword(s):  
Gene Expression ◽  
Transcriptional Activation ◽  
Phorbol Esters ◽  
Marker Gene ◽  
Constitutive Expression ◽  
Regulatory Elements ◽  
Functional Assay ◽  
Rnase Protection ◽  
Intron 1 ◽  
Timp Gene

The expression of the gene for the murine tissue inhibitor of metalloproteinases (TIMP) is induced in response to viruses, growth factors, and phorbol esters. In this report we show that the accumulation of TIMP mRNA after Newcastle disease virus induction is caused by transcriptional activation of the gene. Comparison of the sequences of cDNA and genomic clones along with RNase protection and primer extension analyses revealed that the murine TIMP gene possesses multiple cap sites and that the exon 1 consists exclusively of 5'-noncoding sequences. We observed that DNA regions analogous to those found upstream of the virus-inducible interferon genes are present within intron 1 of the TIMP gene. To investigate the possible role of TIMP intron 1 in gene expression, we used a functional assay based on the transfection of plasmids in which the DNA segment to be tested is placed in proximity to a marker gene driven by the heterologous herpes simplex virus thymidine kinase promoter. Our results indicate that TIMP intron 1 contains DNA sequence elements capable of modulating the activity of a heterologous promoter in two different ways: (i) by enhancing constitutive expression and (ii) by conferring virus inducibility. These results suggest that intron 1 may be involved in the transcriptional regulation of TIMP gene expression.

scholarly journals Transcriptional Activation of Arabidopsis Zygotes Is Required for Initial Cell Divisions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ping Kao ◽  
Michael D. Nodine
Keyword(s):  
Transcriptional Activation ◽  
Gene Products ◽  
Zygotic Genome Activation ◽  
Microscopy Technique ◽  
Early Embryos ◽  
Maternal To Zygotic Transition ◽  
Parental Gene ◽  
Active Transcription ◽  
Genome Activation ◽  
Zygotic Genome

AbstractCommonly referred to as the maternal-to-zygotic transition, the shift of developmental control from maternal-to-zygotic genomes is a key event during animal and plant embryogenesis. Together with the degradation of parental gene products, the increased transcriptional activities of the zygotic genome remodels the early embryonic transcriptome during this transition. Although evidence from multiple flowering plants suggests that zygotes become transcriptionally active soon after fertilization, the timing and developmental requirements of zygotic genome activation in Arabidopsis thaliana (Arabidopsis) remained a matter of debate until recently. In this report, we optimized an expansion microscopy technique for robust immunostaining of Arabidopsis ovules and seeds. This enabled the detection of marks indicative of active transcription in zygotes before the first cell division. Moreover, we employed a live-imaging culture system together with transcriptional inhibitors to demonstrate that such active transcription is physiologically required in zygotes and early embryos. Our results indicate that zygotic genome activation occurs soon after fertilization and is required for the initial zygotic divisions in Arabidopsis.

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