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Fukushima HS, Ikeda T, Ikeda S, Takeda H. Cell cycle length governs heterochromatin reprogramming during early development in non-mammalian vertebrates. EMBO Rep 2024; 25:3300-3323. [PMID: 38943003 PMCID: PMC11315934 DOI: 10.1038/s44319-024-00188-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 06/06/2024] [Accepted: 06/12/2024] [Indexed: 06/30/2024] Open
Abstract
Heterochromatin marks such as H3K9me3 undergo global erasure and re-establishment after fertilization, and the proper reprogramming of H3K9me3 is essential for early development. Despite the widely conserved dynamics of heterochromatin reprogramming in invertebrates and non-mammalian vertebrates, previous studies have shown that the underlying mechanisms may differ between species. Here, we investigate the molecular mechanism of H3K9me3 dynamics in medaka (Japanese killifish, Oryzias latipes) as a non-mammalian vertebrate model, and show that rapid cell cycle during cleavage stages causes DNA replication-dependent passive erasure of H3K9me3. We also find that cell cycle slowing, toward the mid-blastula transition, permits increasing nuclear accumulation of H3K9me3 histone methyltransferase Setdb1, leading to the onset of H3K9me3 re-accumulation. We further demonstrate that cell cycle length in early development also governs H3K9me3 reprogramming in zebrafish and Xenopus laevis. Together with the previous studies in invertebrates, we propose that a cell cycle length-dependent mechanism for both global erasure and re-accumulation of H3K9me3 is conserved among rapid-cleavage species of non-mammalian vertebrates and invertebrates such as Drosophila, C. elegans, Xenopus and teleost fish.
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Affiliation(s)
- Hiroto S Fukushima
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.
- Center for Integrative Medical Sciences, RIKEN, Yokohama, 230-0045, Japan.
| | - Takafumi Ikeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan
- Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto, 603-8555, Japan
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, 603-8555, Japan
| | - Shinra Ikeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Hiroyuki Takeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, 603-8555, Japan.
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2
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Bhatt AD, Brown MG, Wackford AB, Shindo Y, Amodeo AA. Local nuclear to cytoplasmic ratio regulates chaperone-dependent H3 variant incorporation during zygotic genome activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.15.603602. [PMID: 39071352 PMCID: PMC11275841 DOI: 10.1101/2024.07.15.603602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Early embryos often have relatively unstructured chromatin that lacks active and inactive domains typical of differentiated cells. In many species, these regulatory domains are established during zygotic genome activation (ZGA). In Drosophila, ZGA occurs after 13 fast, reductive, syncytial nuclear divisions during which the nuclear to cytoplasmic (N/C) ratio grows exponentially. These divisions incorporate maternally-loaded, cytoplasmic pools of histones into chromatin. Previous work found that chromatin incorporation of replication-coupled histone H3 decreases while its variant H3.3 increases in the cell cycles leading up to ZGA. In other cell types, H3.3 is associated with sites of active transcription as well as heterochromatin, suggesting a link between H3.3 incorporation and ZGA. Here, we examine the factors that contribute to H3.3 incorporation at ZGA. We identify a more rapid decrease in the nuclear availability of H3 than H3.3 over the final pre-ZGA cycles. We also observe an N/C ratio-dependent increase in H3.3 incorporation in mutant embryos with non-uniform local N/C ratios. We find that chaperone binding, not gene expression, controls incorporation patterns using H3/H3.3 chimeric proteins at the endogenous H3.3A locus. We test the specificity of the H3.3 chaperone pathways for H3.3 incorporation using Hira (H3.3 chaperone) mutant embryos. Overall, we propose a model in which local N/C ratios and specific chaperone binding regulate differential incorporation of H3.3 during ZGA.
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Affiliation(s)
- Anusha D. Bhatt
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Madeleine G. Brown
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Aurora B. Wackford
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Yuki Shindo
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Amanda A. Amodeo
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
- Lead contact
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3
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Fang F, Chen D, Basharat AR, Poulos W, Wang Q, Cibelli JB, Liu X, Sun L. Quantitative proteomics reveals the dynamic proteome landscape of zebrafish embryos during the maternal-to-zygotic transition. iScience 2024; 27:109944. [PMID: 38784018 PMCID: PMC11111832 DOI: 10.1016/j.isci.2024.109944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 08/23/2023] [Accepted: 05/06/2024] [Indexed: 05/25/2024] Open
Abstract
Maternal-to-zygotic transition (MZT) is central to early embryogenesis. However, its underlying molecular mechanisms are still not well described. Here, we revealed the expression dynamics of 5,000 proteins across four stages of zebrafish embryos during MZT, representing one of the most systematic surveys of proteome landscape of the zebrafish embryos during MZT. Nearly 700 proteins were differentially expressed and were divided into six clusters according to their expression patterns. The proteome expression profiles accurately reflect the main events that happen during the MZT, i.e., zygotic genome activation (ZGA), clearance of maternal mRNAs, and initiation of cellular differentiation and organogenesis. MZT is modulated by many proteins at multiple levels in a collaborative fashion, i.e., transcription factors, histones, histone-modifying enzymes, RNA helicases, and P-body proteins. Significant discrepancies were discovered between zebrafish proteome and transcriptome profiles during the MZT. The proteome dynamics database will be a valuable resource for bettering our understanding of MZT.
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Affiliation(s)
- Fei Fang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
| | - Daoyang Chen
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
| | - Abdul Rehman Basharat
- Department of BioHealth Informatics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - William Poulos
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - Qianyi Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
| | - Jose B. Cibelli
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824, USA
| | - Xiaowen Liu
- Deming Department of Medicine, School of Medicine, Tulane University, 1441 Canal Street, New Orleans, LA 70112, USA
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
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4
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Brantley S, Di Talia S. The maternal-to-zygotic transition. Curr Biol 2024; 34:R519-R523. [PMID: 38834020 DOI: 10.1016/j.cub.2024.04.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Rapid cleavage divisions and the transition from maternal to zygotic control of gene expression are the hallmarks of early embryonic development in most species. Early development in insects, fish and amphibians is characterized by several short cell cycles with no gap phases, necessary for the rapid production of cells prior to patterning and morphogenesis. Maternal mRNAs and proteins loaded into the egg during oogenesis are essential to drive these rapid early divisions. Once the function of these maternal inputs is complete, the maternal-to-zygotic transition (MZT) marks the handover of developmental control to the gene products synthesized from the zygotic genome. The MZT requires three major events: the removal of a subset of maternal mRNAs, the initiation of zygotic transcription, and the remodeling of the cell cycle. In each species, the MZT occurs at a highly reproducible time during development due to a series of feedback mechanisms that tightly couple these three processes. Dissecting these feedback mechanisms and their spatiotemporal control will be essential to understanding the control of the MZT. In this primer, we outline the mechanisms that govern the major events of the MZT across species and highlight the role of feedback mechanisms that ensure the MZT is precisely timed and orchestrated.
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Affiliation(s)
- Susanna Brantley
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27705, USA
| | - Stefano Di Talia
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27705, USA.
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5
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Yu Y, Wang S, Wang Z, Gao R, Lee J. Arabidopsis thaliana: a powerful model organism to explore histone modifications and their upstream regulations. Epigenetics 2023; 18:2211362. [PMID: 37196184 DOI: 10.1080/15592294.2023.2211362] [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: 11/24/2022] [Revised: 04/07/2023] [Accepted: 04/28/2023] [Indexed: 05/19/2023] Open
Abstract
Histones are subjected to extensive covalent modifications that affect inter-nucleosomal interactions as well as alter chromatin structure and DNA accessibility. Through switching the corresponding histone modifications, the level of transcription and diverse downstream biological processes can be regulated. Although animal systems are widely used in studying histone modifications, the signalling processes that occur outside the nucleus prior to histone modifications have not been well understood due to the limitations including non viable mutants, partial lethality, and infertility of survivors. Here, we review the benefits of using Arabidopsis thaliana as the model organism to study histone modifications and their upstream regulations. Similarities among histones and key histone modifiers such as the Polycomb group (PcG) and Trithorax group (TrxG) in Drosophila, Human, and Arabidopsis are examined. Furthermore, prolonged cold-induced vernalization system has been well-studied and revealed the relationship between the controllable environment input (duration of vernalization), its chromatin modifications of FLOWERING LOCUS C (FLC), following gene expression, and the corresponding phenotypes. Such evidence suggests that research on Arabidopsis can bring insights into incomplete signalling pathways outside of the histone box, which can be achieved through viable reverse genetic screenings based on the phenotypes instead of direct monitoring of histone modifications among individual mutants. The potential upstream regulators in Arabidopsis can provide cues or directions for animal research based on the similarities between them.
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Affiliation(s)
- Yang Yu
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu, China
| | - Sihan Wang
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu, China
| | - Ziqin Wang
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu, China
| | - Renwei Gao
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu, China
| | - Joohyun Lee
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu, China
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6
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Chaubal A, Waldern JM, Taylor C, Laederach A, Marzluff WF, Duronio RJ. Coordinated expression of replication-dependent histone genes from multiple loci promotes histone homeostasis in Drosophila. Mol Biol Cell 2023; 34:ar118. [PMID: 37647143 PMCID: PMC10846616 DOI: 10.1091/mbc.e22-11-0532] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 08/07/2023] [Accepted: 08/24/2023] [Indexed: 09/01/2023] Open
Abstract
Production of large amounts of histone proteins during S phase is critical for proper chromatin formation and genome integrity. This process is achieved in part by the presence of multiple copies of replication dependent (RD) histone genes that occur in one or more clusters in metazoan genomes. In addition, RD histone gene clusters are associated with a specialized nuclear body, the histone locus body (HLB), which facilitates efficient transcription and 3' end-processing of RD histone mRNA. How all five RD histone genes within these clusters are coordinately regulated such that neither too few nor too many histones are produced, a process referred to as histone homeostasis, is not fully understood. Here, we explored the mechanisms of coordinate regulation between multiple RD histone loci in Drosophila melanogaster and Drosophila virilis. We provide evidence for functional competition between endogenous and ectopic transgenic histone arrays located at different chromosomal locations in D. melanogaster that helps maintain proper histone mRNA levels. Consistent with this model, in both species we found that individual histone gene arrays can independently assemble an HLB that results in active histone transcription. Our findings suggest a role for HLB assembly in coordinating RD histone gene expression to maintain histone homeostasis.
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Affiliation(s)
- Ashlesha Chaubal
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599
| | - Justin M. Waldern
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Colin Taylor
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Alain Laederach
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
| | - William F. Marzluff
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599
| | - Robert J. Duronio
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
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7
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Murphy PJ, Berger F. The chromatin source-sink hypothesis: a shared mode of chromatin-mediated regulations. Development 2023; 150:dev201989. [PMID: 38771301 PMCID: PMC10629678 DOI: 10.1242/dev.201989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 09/12/2023] [Indexed: 11/05/2023]
Abstract
We propose that several chromatin-mediated regulatory processes are dominated by source-sink relationships in which factors operate as 'sources' to produce or provide a resource and compete with each other to occupy separate 'sinks'. In this model, large portions of genomic DNA operate as 'sinks', which are filled by 'sources', such as available histone variants, covalent modifications to histones, the readers of these modifications and non-coding RNAs. Competing occupation for the sinks by different sources leads to distinct states of genomic equilibrium in differentiated cells. During dynamic developmental events, such as sexual reproduction, we propose that dramatic and rapid reconfiguration of source-sink relationships modifies chromatin states. We envision that re-routing of sources could occur by altering the dimensions of the sink, by reconfiguration of existing sink occupation or by varying the size of the source, providing a central mechanism to explain a plethora of epigenetic phenomena, which contribute to phenotypic variegation, zygotic genome activation and nucleolar dominance.
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Affiliation(s)
- Patrick J. Murphy
- University of Rochester, Department of Biomedical Genetics and Department of Biology, 601 Elmwood Ave., Rochester NY 14620, USA
| | - Frédéric Berger
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter; Dr. Bohr-Gasse 3, 1030 Vienna, Austria
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8
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Harrison MM, Marsh AJ, Rushlow CA. Setting the stage for development: the maternal-to-zygotic transition in Drosophila. Genetics 2023; 225:iyad142. [PMID: 37616526 PMCID: PMC10550319 DOI: 10.1093/genetics/iyad142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 07/18/2023] [Indexed: 08/26/2023] Open
Abstract
The zygote has a daunting task ahead of itself; it must develop from a single cell (fertilized egg) into a fully functioning adult with a multitude of different cell types. In the beginning, the zygote has help from its mother, in the form of gene products deposited into the egg, but eventually, it must rely on its own resources to proceed through development. The transfer of developmental control from the mother to the embryo is called the maternal-to-zygotic transition (MZT). All animals undergo this transition, which is defined by two main processes-the degradation of maternal RNAs and the synthesis of new RNAs from the zygote's own genome. Here, we review the regulation of the MZT in Drosophila, but given the broad conservation of this essential process, much of the regulation is shared among metazoans.
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Affiliation(s)
- Melissa M Harrison
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706USA
| | - Audrey J Marsh
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706USA
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9
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Yamamoto T, Kinoshita K, Hirano T. Elasticity control of entangled chromosomes: Crosstalk between condensin complexes and nucleosomes. Biophys J 2023; 122:3869-3881. [PMID: 37571823 PMCID: PMC10560673 DOI: 10.1016/j.bpj.2023.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/18/2023] [Accepted: 08/08/2023] [Indexed: 08/13/2023] Open
Abstract
Condensin-mediated loop extrusion is now considered as the main driving force of mitotic chromosome assembly. Recent experiments have shown, however, that a class of mutant condensin complexes deficient in loop extrusion can assemble chromosome-like structures in Xenopus egg extracts, although these structures are somewhat different from those assembled by wild-type condensin complexes. In the absence of topoisomerase II (topo II), the mutant condensin complexes produce an unusual round-shaped structure termed a bean, which consists of a DNA-dense central core surrounded by a DNA-sparse halo. The mutant condensin complexes accumulate in the core, whereas histones are more concentrated in the halo than in the core. We consider that this peculiar structure serves as a model system to study how DNA entanglements, nucleosomes, and condensin functionally crosstalk with each other. To gain insight into how the bean structure is formed, here we construct a theoretical model. Our theory predicts that the core is formed by attractive interactions between mutant condensin complexes, whereas the halo is stabilized by the energy reduction through the selective accumulation of nucleosomes. The formation of the halo increases the elastic free energy due to the DNA entanglement in the core, but the latter free energy is compensated by condensin complexes that suppress the assembly of nucleosomes.
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Affiliation(s)
- Tetsuya Yamamoto
- Institute for Chemical Reaction Design and Discovery (ICReDD), Hokkaido University, Sapporo, Hokkaido, Japan.
| | | | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan
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10
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Zhou CY, Heald R. Principles of genome activation in the early embryo. Curr Opin Genet Dev 2023; 81:102062. [PMID: 37339553 DOI: 10.1016/j.gde.2023.102062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/17/2023] [Accepted: 05/18/2023] [Indexed: 06/22/2023]
Abstract
A major hurdle in an embryo's life is the initiation of its own transcriptional program, a process termed Zygotic Genome Activation (ZGA). In many species, ZGA is intricately timed, with bulk transcription initiating at the end of a series of reductive cell divisions when cell cycle duration increases. At the same time, major changes in genome architecture give rise to chromatin states that are permissive to RNA polymerase II activity. Yet, we still do not understand the series of events that trigger gene expression at the right time and in the correct sequence. Here we discuss new discoveries that deepen our understanding of how zygotic genes are primed for transcription, and how these events are regulated by the cell cycle and nuclear import. Finally, we speculate on the evolutionary basis of ZGA timing as an exciting future direction for the field.
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Affiliation(s)
- Coral Y Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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11
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Ayers TN, Nicotra ML, Lee MT. Parallels and contrasts between the cnidarian and bilaterian maternal-to-zygotic transition are revealed in Hydractinia embryos. PLoS Genet 2023; 19:e1010845. [PMID: 37440598 PMCID: PMC10368294 DOI: 10.1371/journal.pgen.1010845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/25/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
Embryogenesis requires coordinated gene regulatory activities early on that establish the trajectory of subsequent development, during a period called the maternal-to-zygotic transition (MZT). The MZT comprises transcriptional activation of the embryonic genome and post-transcriptional regulation of egg-inherited maternal mRNA. Investigation into the MZT in animals has focused almost exclusively on bilaterians, which include all classical models such as flies, worms, sea urchin, and vertebrates, thus limiting our capacity to understand the gene regulatory paradigms uniting the MZT across all animals. Here, we elucidate the MZT of a non-bilaterian, the cnidarian Hydractinia symbiolongicarpus. Using parallel poly(A)-selected and non poly(A)-dependent RNA-seq approaches, we find that the Hydractinia MZT is composed of regulatory activities similar to many bilaterians, including cytoplasmic readenylation of maternally contributed mRNA, delayed genome activation, and separate phases of maternal mRNA deadenylation and degradation that likely depend on both maternally and zygotically encoded clearance factors, including microRNAs. But we also observe massive upregulation of histone genes and an expanded repertoire of predicted H4K20 methyltransferases, aspects thus far particular to the Hydractinia MZT and potentially underlying a novel mode of early embryonic chromatin regulation. Thus, similar regulatory strategies with taxon-specific elaboration underlie the MZT in both bilaterian and non-bilaterian embryos, providing insight into how an essential developmental transition may have arisen in ancestral animals.
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Affiliation(s)
- Taylor N. Ayers
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh Pennsylvania, United States of America
| | - Matthew L. Nicotra
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Miler T. Lee
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh Pennsylvania, United States of America
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12
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Ayers TN, Nicotra ML, Lee MT. Parallels and contrasts between the cnidarian and bilaterian maternal-to-zygotic transition are revealed in Hydractinia embryos. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.09.540083. [PMID: 37214839 PMCID: PMC10197650 DOI: 10.1101/2023.05.09.540083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Embryogenesis requires coordinated gene regulatory activities early on that establish the trajectory of subsequent development, during a period called the maternal-to-zygotic transition (MZT). The MZT comprises transcriptional activation of the embryonic genome and post-transcriptional regulation of egg-inherited maternal mRNA. Investigation into the MZT in animals has focused almost exclusively on bilaterians, which include all classical models such as flies, worms, sea urchin, and vertebrates, thus limiting our capacity to understand the gene regulatory paradigms uniting the MZT across all animals. Here, we elucidate the MZT of a non-bilaterian, the cnidarian Hydractinia symbiolongicarpus . Using parallel poly(A)-selected and non poly(A)-dependent RNA-seq approaches, we find that the Hydractinia MZT is composed of regulatory activities analogous to many bilaterians, including cytoplasmic readenylation of maternally contributed mRNA, delayed genome activation, and separate phases of maternal mRNA deadenylation and degradation that likely depend on both maternally and zygotically encoded clearance factors, including microRNAs. But we also observe massive upregulation of histone genes and an expanded repertoire of predicted H4K20 methyltransferases, aspects thus far unique to the Hydractinia MZT and potentially underlying a novel mode of early embryonic chromatin regulation. Thus, similar regulatory strategies with taxon-specific elaboration underlie the MZT in both bilaterian and non-bilaterian embryos, providing insight into how an essential developmental transition may have arisen in ancestral animals.
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Affiliation(s)
- Taylor N. Ayers
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh PA 15213 U.S.A
| | - Matthew L. Nicotra
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA 15261 U.S.A
| | - Miler T. Lee
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh PA 15213 U.S.A
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13
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Zhou CY, Dekker B, Liu Z, Cabrera H, Ryan J, Dekker J, Heald R. Mitotic chromosomes scale to nuclear-cytoplasmic ratio and cell size in Xenopus. eLife 2023; 12:e84360. [PMID: 37096661 PMCID: PMC10260010 DOI: 10.7554/elife.84360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 04/21/2023] [Indexed: 04/26/2023] Open
Abstract
During the rapid and reductive cleavage divisions of early embryogenesis, subcellular structures such as the nucleus and mitotic spindle scale to decreasing cell size. Mitotic chromosomes also decrease in size during development, presumably to scale coordinately with mitotic spindles, but the underlying mechanisms are unclear. Here we combine in vivo and in vitro approaches using eggs and embryos from the frog Xenopus laevis to show that mitotic chromosome scaling is mechanistically distinct from other forms of subcellular scaling. We found that mitotic chromosomes scale continuously with cell, spindle, and nuclear size in vivo. However, unlike for spindles and nuclei, mitotic chromosome size cannot be reset by cytoplasmic factors from earlier developmental stages. In vitro, increasing nuclear-cytoplasmic (N/C) ratio is sufficient to recapitulate mitotic chromosome scaling, but not nuclear or spindle scaling, through differential loading of maternal factors during interphase. An additional pathway involving importin α scales mitotic chromosomes to cell surface area/volume ratio (SA/V) during metaphase. Finally, single-chromosome immunofluorescence and Hi-C data suggest that mitotic chromosomes shrink during embryogenesis through decreased recruitment of condensin I, resulting in major rearrangements of DNA loop architecture to accommodate the same amount of DNA on a shorter chromosome axis. Together, our findings demonstrate how mitotic chromosome size is set by spatially and temporally distinct developmental cues in the early embryo.
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Affiliation(s)
- Coral Y Zhou
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Bastiaan Dekker
- Department of Systems Biology, University of Massachusetts Medical SchoolWorcesterUnited States
| | - Ziyuan Liu
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Hilda Cabrera
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Joel Ryan
- Advanced BioImaging Facility, McGill UniversityMontrealCanada
| | - Job Dekker
- Department of Systems Biology, University of Massachusetts Medical SchoolWorcesterUnited States
- Howard Hughes Medical InstituteChevy ChaseUnited States
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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14
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Du Q, Peng F, Xiong Q, Xu K, Yang KY, Wang M, Wu Z, Li S, Cheng X, Rao X, Wang Y, Tsui SKW, Zeng X. Genomic Analysis of Amphioxus Reveals a Wide Range of Fragments Homologous to Viral Sequences. Viruses 2023; 15:v15040909. [PMID: 37112889 PMCID: PMC10145014 DOI: 10.3390/v15040909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/11/2023] [Accepted: 03/28/2023] [Indexed: 04/05/2023] Open
Abstract
Amphioxus species are considered living fossils and are important in the evolutionary study of chordates and vertebrates. To explore viral homologous sequences, a high-quality annotated genome of the Beihai amphioxus (Branchiostoma belcheri beihai) was examined using virus sequence queries. In this study, 347 homologous fragments (HFs) of viruses were identified in the genome of B. belcheri beihai, of which most were observed on 21 genome assembly scaffolds. HFs were preferentially located within protein-coding genes, particularly in their CDS regions and promoters. A range of amphioxus genes with a high frequency of HFs is proposed, including histone-related genes that are homologous to the Histone H4 or Histone H2B domains of viruses. Together, this comprehensive analysis of viral HFs provides insights into the neglected role of viral integration in the evolution of amphioxus.
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Affiliation(s)
- Qiao Du
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Fang Peng
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Qing Xiong
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong, Hong Kong, China
| | - Kejin Xu
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Kevin Yi Yang
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong, Hong Kong, China
| | - Mingqiang Wang
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zhitian Wu
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Shanying Li
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiaorui Cheng
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Xinjie Rao
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Yuyouye Wang
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Stephen Kwok-Wing Tsui
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong, Hong Kong, China
| | - Xi Zeng
- Agricultural Bioinformatics Key Laboratory of Hubei Province and 3D Genomics Research Centre, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
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15
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Olivetta M, Dudin O. The nuclear-to-cytoplasmic ratio drives cellularization in the close animal relative Sphaeroforma arctica. Curr Biol 2023; 33:1597-1605.e3. [PMID: 36996815 DOI: 10.1016/j.cub.2023.03.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/17/2023] [Accepted: 03/07/2023] [Indexed: 03/31/2023]
Abstract
The ratio of nuclear content to cytoplasmic volume (N/C ratio) is a key regulator driving the maternal-to-zygotic transition in most animal embryos. Altering this ratio often impacts zygotic genome activation and deregulates the timing and outcome of embryogenesis.1,2,3 Despite being ubiquitous across animals, little is known about when the N/C ratio evolved to control multicellular development. Such capacity either originated with the emergence of animal multicellularity or was co-opted from the mechanisms present in unicellular organisms.4 An effective strategy to tackle this question is to investigate the close relatives of animals exhibiting life cycles with transient multicellular stages.5 Among these are ichthyosporeans, a lineage of protists undergoing coenocytic development followed by cellularization and cell release.6,7,8 During cellularization, a transient multicellular stage resembling animal epithelia is generated, offering a unique opportunity to examine whether the N/C ratio regulates multicellular development. Here, we use time-lapse microscopy to characterize how the N/C ratio affects the life cycle of the best-studied ichthyosporean model, Sphaeroforma arctica. We uncover that the last stages of cellularization coincide with a significant increase in the N/C ratio. Increasing the N/C ratio by reducing the coenocytic volume accelerates cellularization, whereas decreasing the N/C ratio by lowering the nuclear content halts it. Moreover, centrifugation and pharmacological inhibitor experiments suggest that the N/C ratio is locally sensed at the cortex and relies on phosphatase activity. Altogether, our results show that the N/C ratio drives cellularization in S. arctica, suggesting that its capacity to control multicellular development predates animal emergence.
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16
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Hadzhiev Y, Wheatley L, Cooper L, Ansaloni F, Whalley C, Chen Z, Finaurini S, Gustincich S, Sanges R, Burgess S, Beggs A, Müller F. The miR-430 locus with extreme promoter density forms a transcription body during the minor wave of zygotic genome activation. Dev Cell 2023; 58:155-170.e8. [PMID: 36693321 PMCID: PMC9904021 DOI: 10.1016/j.devcel.2022.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 08/10/2022] [Accepted: 12/16/2022] [Indexed: 01/24/2023]
Abstract
In anamniote embryos, the major wave of zygotic genome activation starts during the mid-blastula transition. However, some genes escape global genome repression, are activated substantially earlier, and contribute to the minor wave of genome activation. The mechanisms underlying the minor wave of genome activation are little understood. We explored the genomic organization and cis-regulatory mechanisms of a transcription body, in which the minor wave of genome activation is first detected in zebrafish. We identified the miR-430 cluster as having excessive copy number and the highest density of Pol-II-transcribed promoters in the genome, and this is required for forming the transcription body. However, this transcription body is not essential for, nor does it encompasse, minor wave transcription globally. Instead, distinct minor-wave-specific promoter architecture suggests that promoter-autonomous mechanisms regulate the minor wave of genome activation. The minor-wave-specific features also suggest distinct transcription initiation mechanisms between the minor and major waves of genome activation.
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Affiliation(s)
- Yavor Hadzhiev
- Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Lucy Wheatley
- Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Ledean Cooper
- Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Federico Ansaloni
- Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK; Area of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy; Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), 16163 Genoa, Italy
| | - Celina Whalley
- Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Zhelin Chen
- South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-2152, USA
| | - Sara Finaurini
- Area of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy
| | - Stefano Gustincich
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), 16163 Genoa, Italy
| | - Remo Sanges
- Area of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy; Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), 16163 Genoa, Italy
| | - Shawn Burgess
- Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-2152, USA
| | - Andrew Beggs
- Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Ferenc Müller
- Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK.
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17
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Kuznetsova K, Chabot NM, Ugolini M, Wu E, Lalit M, Oda H, Sato Y, Kimura H, Jug F, Vastenhouw NL. Nanog organizes transcription bodies. Curr Biol 2023; 33:164-173.e5. [PMID: 36476751 DOI: 10.1016/j.cub.2022.11.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 09/21/2022] [Accepted: 11/07/2022] [Indexed: 12/12/2022]
Abstract
The localization of transcriptional activity in specialized transcription bodies is a hallmark of gene expression in eukaryotic cells.1-3 How proteins of the transcriptional machinery come together to form such bodies, however, is unclear. Here, we take advantage of two large, isolated, and long-lived transcription bodies that reproducibly form during early zebrafish embryogenesis to characterize the dynamics of transcription body formation. Once formed, these transcription bodies are enriched for initiating and elongating RNA polymerase II, as well as the transcription factors Nanog and Sox19b. Analyzing the events leading up to transcription, we find that Nanog and Sox19b cluster prior to transcription. The clustering of transcription factors is sequential; Nanog clusters first, and this is required for the clustering of Sox19b and the initiation of transcription. Mutant analysis revealed that both the DNA-binding domain as well as one of the two intrinsically disordered regions of Nanog are required to organize the two bodies of transcriptional activity. Taken together, our data suggest that the clustering of transcription factors dictates the formation of transcription bodies.
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Affiliation(s)
- Ksenia Kuznetsova
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Noémie M Chabot
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Center for Integrative Genomics, University of Lausanne, Quartier Sorge, 1015 Lausanne, Switzerland
| | - Martino Ugolini
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Center for Integrative Genomics, University of Lausanne, Quartier Sorge, 1015 Lausanne, Switzerland
| | - Edlyn Wu
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Center for Integrative Genomics, University of Lausanne, Quartier Sorge, 1015 Lausanne, Switzerland
| | - Manan Lalit
- Center for Systems Biology Dresden, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Haruka Oda
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Yuko Sato
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Florian Jug
- Center for Systems Biology Dresden, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Fondazione Human Technopole, Viale Rita Levi-Montalcini 1, Area MIND, 20157 Milano, Italy
| | - Nadine L Vastenhouw
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Center for Integrative Genomics, University of Lausanne, Quartier Sorge, 1015 Lausanne, Switzerland.
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18
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Cell-type specific profiling of histone post-translational modifications in the adult mouse striatum. Nat Commun 2022; 13:7720. [PMID: 36513652 PMCID: PMC9747932 DOI: 10.1038/s41467-022-35384-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 11/25/2022] [Indexed: 12/15/2022] Open
Abstract
Epigenetic gene regulation in the heterogeneous brain remains challenging to decipher with current strategies. Bulk tissue analysis from pooled subjects reflects the average of cell-type specific changes across cell-types and individuals, which obscures causal relationships between epigenetic modifications, regulation of gene expression, and complex pathology. To address these limitations, we optimized a hybrid protocol, ICuRuS, for the isolation of nuclei tagged in specific cell-types and histone post translational modification profiling from the striatum of a single mouse. We combined affinity-based isolation of the medium spiny neuron subtypes, Adenosine 2a Receptor or Dopamine Receptor D1, with cleavage of histone-DNA complexes using an antibody-targeted micrococcal nuclease to release DNA complexes for paired end sequencing. Unlike fluorescence activated cell sorting paired with chromatin immunoprecipitation, ICuRuS allowed for robust epigenetic profiling at cell-type specific resolution. Our analysis provides a framework to understand combinatorial relationships between neuronal-subtype-specific epigenetic modifications and gene expression.
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19
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Balachandra S, Sarkar S, Amodeo AA. The Nuclear-to-Cytoplasmic Ratio: Coupling DNA Content to Cell Size, Cell Cycle, and Biosynthetic Capacity. Annu Rev Genet 2022; 56:165-185. [PMID: 35977407 PMCID: PMC10165727 DOI: 10.1146/annurev-genet-080320-030537] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Though cell size varies between different cells and across species, the nuclear-to-cytoplasmic (N/C) ratio is largely maintained across species and within cell types. A cell maintains a relatively constant N/C ratio by coupling DNA content, nuclear size, and cell size. We explore how cells couple cell division and growth to DNA content. In some cases, cells use DNA as a molecular yardstick to control the availability of cell cycle regulators. In other cases, DNA sets a limit for biosynthetic capacity. Developmentally programmed variations in the N/C ratio for a given cell type suggest that a specific N/C ratio is required to respond to given physiological demands. Recent observations connecting decreased N/C ratios with cellular senescence indicate that maintaining the proper N/C ratio is essential for proper cellular functioning. Together, these findings suggest a causative, not simply correlative, role for the N/C ratio in regulating cell growth and cell cycle progression.
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Affiliation(s)
- Shruthi Balachandra
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA; ,
| | - Sharanya Sarkar
- Department of Microbiology and Immunology, Dartmouth College, Hanover, New Hampshire, USA;
| | - Amanda A Amodeo
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA; ,
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20
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Pluta R, Aragón E, Prescott NA, Ruiz L, Mees RA, Baginski B, Flood JR, Martin-Malpartida P, Massagué J, David Y, Macias MJ. Molecular basis for DNA recognition by the maternal pioneer transcription factor FoxH1. Nat Commun 2022; 13:7279. [PMID: 36435807 PMCID: PMC9701222 DOI: 10.1038/s41467-022-34925-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 11/10/2022] [Indexed: 11/28/2022] Open
Abstract
Forkhead box H1 (FoxH1) is an essential maternal pioneer factor during embryonic development that binds to specific GG/GT-containing DNA target sequences. Here we have determined high-resolution structures of three FoxH1 proteins (from human, frog and fish species) and four DNAs to clarify the way in which FoxH1 binds to these sites. We found that the protein-DNA interactions extend to both the minor and major DNA grooves and are thus almost twice as extensive as those of other FOX family members. Moreover, we identified two specific amino acid changes in FoxH1 that allowed the recognition of GG/GT motifs. Consistent with the pioneer factor activity of FoxH1, we found that its affinity for nucleosomal DNA is even higher than for linear DNA fragments. The structures reported herein illustrate how FoxH1 binding to distinct DNA sites provides specificity and avoids cross-regulation by other FOX proteins that also operate during the maternal-zygotic transition and select canonical forkhead sites.
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Affiliation(s)
- Radoslaw Pluta
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Eric Aragón
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Nicholas A Prescott
- Tri-Institutional PhD Program in Chemical Biology, New York, NY, USA
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Lidia Ruiz
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Rebeca A Mees
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Blazej Baginski
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Julia R Flood
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Pau Martin-Malpartida
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Joan Massagué
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Yael David
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
- Department of Pharmacology, Weill Cornell Medicine, New York, NY, 10065, USA
- Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Maria J Macias
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, Barcelona, 08010, Spain.
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21
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Differential nuclear import sets the timing of protein access to the embryonic genome. Nat Commun 2022; 13:5887. [PMID: 36202846 PMCID: PMC9537182 DOI: 10.1038/s41467-022-33429-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 09/16/2022] [Indexed: 02/02/2023] Open
Abstract
The development of a fertilized egg to an embryo requires the proper temporal control of gene expression. During cell differentiation, timing is often controlled via cascades of transcription factors (TFs). However, in early development, transcription is often inactive, and many TF levels stay constant, suggesting that alternative mechanisms govern the observed rapid and ordered onset of gene expression. Here, we find that in early embryonic development access of maternally deposited nuclear proteins to the genome is temporally ordered via importin affinities, thereby timing the expression of downstream targets. We quantify changes in the nuclear proteome during early development and find that nuclear proteins, such as TFs and RNA polymerases, enter the nucleus sequentially. Moreover, we find that the timing of nuclear proteins' access to the genome corresponds to the timing of downstream gene activation. We show that the affinity of proteins to importin is a major determinant in the timing of protein entry into embryonic nuclei. Thus, we propose a mechanism by which embryos encode the timing of gene expression in early development via biochemical affinities. This process could be critical for embryos to organize themselves before deploying the regulatory cascades that control cell identities.
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22
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Zhao Y, Vartak SV, Conte A, Wang X, Garcia DA, Stevens E, Kyoung Jung S, Kieffer-Kwon KR, Vian L, Stodola T, Moris F, Chopp L, Preite S, Schwartzberg PL, Kulinski JM, Olivera A, Harly C, Bhandoola A, Heuston EF, Bodine DM, Urrutia R, Upadhyaya A, Weirauch MT, Hager G, Casellas R. "Stripe" transcription factors provide accessibility to co-binding partners in mammalian genomes. Mol Cell 2022; 82:3398-3411.e11. [PMID: 35863348 PMCID: PMC9481673 DOI: 10.1016/j.molcel.2022.06.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 04/06/2022] [Accepted: 06/22/2022] [Indexed: 10/17/2022]
Abstract
Regulatory elements activate promoters by recruiting transcription factors (TFs) to specific motifs. Notably, TF-DNA interactions often depend on cooperativity with colocalized partners, suggesting an underlying cis-regulatory syntax. To explore TF cooperativity in mammals, we analyze ∼500 mouse and human primary cells by combining an atlas of TF motifs, footprints, ChIP-seq, transcriptomes, and accessibility. We uncover two TF groups that colocalize with most expressed factors, forming stripes in hierarchical clustering maps. The first group includes lineage-determining factors that occupy DNA elements broadly, consistent with their key role in tissue-specific transcription. The second one, dubbed universal stripe factors (USFs), comprises ∼30 SP, KLF, EGR, and ZBTB family members that recognize overlapping GC-rich sequences in all tissues analyzed. Knockouts and single-molecule tracking reveal that USFs impart accessibility to colocalized partners and increase their residence time. Mammalian cells have thus evolved a TF superfamily with overlapping DNA binding that facilitate chromatin accessibility.
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Affiliation(s)
- Yongbing Zhao
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA.
| | - Supriya V Vartak
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - Andrea Conte
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - Xiang Wang
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - David A Garcia
- Laboratory of Receptor Biology and Gene Expression, NCI, NIH, Bethesda, MD 20893, USA; Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Evan Stevens
- Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - Seol Kyoung Jung
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | | | - Laura Vian
- Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - Timothy Stodola
- Genomic Sciences and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Francisco Moris
- EntreChem S.L., Vivero Ciencias de la Salud, 33011 Oviedo, Spain
| | - Laura Chopp
- Laboratory of Immune Cell Biology, NCI, NIH, Bethesda, MD 20892, USA
| | - Silvia Preite
- Laboratory of Immune System Biology, NIAID, NIH, Bethesda, MD 20892, USA
| | | | - Joseph M Kulinski
- Mast cell Biology Section, Laboratory of Allergic Diseases, NIAID, NIH, Bethesda, MD 20892, USA
| | - Ana Olivera
- Mast cell Biology Section, Laboratory of Allergic Diseases, NIAID, NIH, Bethesda, MD 20892, USA
| | - Christelle Harly
- Laboratory of Genome Integrity, NCI, NIH, Bethesda, MD 20892, USA
| | | | | | - David M Bodine
- Genetics and Molecular Biology Branch, NHGRI, NIH, Bethesda, MD 20892, USA
| | - Raul Urrutia
- Genomic Sciences and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Matthew T Weirauch
- Divisions of Biomedical Informatics and Developmental Biology, Center for Autoimmune Genomics and Etiology (CAGE), Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Gordon Hager
- Laboratory of Receptor Biology and Gene Expression, NCI, NIH, Bethesda, MD 20893, USA
| | - Rafael Casellas
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA.
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23
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Larson ED, Komori H, Fitzpatrick ZA, Krabbenhoft SD, Lee CY, Harrison M. Premature translation of the Drosophila zygotic genome activator Zelda is not sufficient to precociously activate gene expression. G3 (BETHESDA, MD.) 2022; 12:6649735. [PMID: 35876878 PMCID: PMC9434156 DOI: 10.1093/g3journal/jkac159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 06/15/2022] [Indexed: 05/22/2023]
Abstract
Following fertilization, the unified germ cells rapidly transition to a totipotent embryo. Maternally deposited mRNAs encode the proteins necessary for this reprogramming as the zygotic genome remains transcriptionally quiescent during the initial stages of development. The transcription factors required to activate the zygotic genome are among these maternally deposited mRNAs and are robustly translated following fertilization. In Drosophila, the mRNA encoding Zelda, the major activator of the zygotic genome, is not translated until 1 h after fertilization. Here we demonstrate that zelda translation is repressed in the early embryo by the TRIM-NHL protein Brain tumor (BRAT). BRAT also regulates Zelda levels in the larval neuroblast lineage. In the embryo, BRAT-mediated translational repression is regulated by the Pan Gu kinase, which is triggered by egg activation. The Pan Gu kinase phosphorylates translational regulators, suggesting that Pan Gu kinase activity alleviates translational repression of zelda by BRAT and coupling translation of zelda with that of other regulators of early embryonic development. Using the premature translation of zelda in embryos lacking BRAT activity, we showed that early translation of a zygotic genome activator is not sufficient to drive precocious gene expression. Instead, Zelda-target genes showed increased expression at the time they are normally activated. We propose that transition through early development requires the integration of multiple processes, including the slowing of the nuclear division cycle and activation of the zygotic genome. These processes are coordinately controlled by Pan Gu kinase-mediated regulation of translation.
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Affiliation(s)
- Elizabeth D Larson
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hideyuki Komori
- Department of Cell and Developmental Biology and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Zoe A Fitzpatrick
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Samuel D Krabbenhoft
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Cheng-Yu Lee
- Department of Cell and Developmental Biology and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Melissa Harrison
- Corresponding author: Department of Biomolecular Chemistry, University of Wisconsin-Madison, 440 Henry Mall, 6204B Biochemical Sciences Building, Madison, WI 53706, USA.
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24
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Hu R, Xu Y, Han B, Chen Y, Li W, Guan G, Hu P, Zhou Y, Xu Q, Chen L. MiR-202-3p determines embryo viability during mid-blastula transition. Front Cell Dev Biol 2022; 10:897826. [PMID: 36003151 PMCID: PMC9393261 DOI: 10.3389/fcell.2022.897826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 07/13/2022] [Indexed: 11/13/2022] Open
Abstract
Developmental growth is an intricate process involving the coordinated regulation of the expression of various genes, and microRNAs (miRNAs) play crucial roles in diverse processes throughout animal development. The mid-blastula transition (MBT) is a developmental milestone when maternal RNAs are cleared and the zygotic genome programmed asynchronous cell division begins to drive embryogenesis. While mechanisms underlying MBT have been intensively revealed, factors regulating cell proliferation at the transition remain largely unknown. We report here a microRNA, miR-202-3p to be a key factor that determines embryonic fate during MBT in zebrafish. A miR-202-3p antagomir specifically terminated embryo development at the mid-blastula stage. In vivo deletion of the miR-202 locus recapitulated the fatal phenotypes, which were rescued only by miR-202-3p or its precursor. Transcriptome comparison revealed >250 RNAs including both maternal and zygotic origins were dysregulated at MBT in the miR-202−/− embryos, corresponding with arrays of homeostatic disorders leading to massive apoptosis. A trio of genes: nfkbiaa, perp and mgll, known to be intimately involved with cell proliferation and survival, were identified as direct targets of miR-202-3p. Importantly, over- or under-expression of any of the trio led to developmental delay or termination at the blastula or gastrula stages. Furthermore, nfkbiaa and perp were shown to inter-regulate each other. Thus, miR-202-3p mediates a regulatory network whose components interact closely during MBT to determine embryonic viability and development.
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Affiliation(s)
- Ruiqin Hu
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Yanna Xu
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Bingshe Han
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Yi Chen
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Wenhao Li
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Guijun Guan
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Peng Hu
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Yan Zhou
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Qianghua Xu
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, College of Marine Science, Shanghai Ocean University, Shanghai, China
| | - Liangbiao Chen
- International Joint Research Centre for Marine Biosciences (Ministry of Science and Technology), College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Ministry of Education) and International Research Centre for Marine Biosciences, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
- *Correspondence: Liangbiao Chen,
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25
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Talbert PB, Armache KJ, Henikoff S. Viral histones: pickpocket's prize or primordial progenitor? Epigenetics Chromatin 2022; 15:21. [PMID: 35624484 PMCID: PMC9145170 DOI: 10.1186/s13072-022-00454-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/19/2022] [Indexed: 12/12/2022] Open
Abstract
The common histones H2A, H2B, H3, and H4 are the characteristic components of eukaryotic nucleosomes, which function to wrap DNA and compact the genome as well as to regulate access to DNA for transcription and replication in all eukaryotes. In the past two decades, histones have also been found to be encoded in some DNA viruses, where their functions and properties are largely unknown, though recently histones from two related viruses have been shown to form nucleosome-like structures in vitro. Viral histones can be highly similar to eukaryotic histones in primary sequence, suggesting they have been recently picked up from eukaryotic hosts, or they can be radically divergent in primary sequence and may occur as conjoined histone doublets, triplets, or quadruplets, suggesting ancient origins prior to the divergence of modern eukaryotes. Here, we review what is known of viral histones and discuss their possible origins and functions. We consider how the viral life cycle may affect their properties and histories, and reflect on the possible roles of viruses in the origin of the nucleus of modern eukaryotic cells.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute and Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Seattle, WA, 98109, USA
| | - Karim-Jean Armache
- Skirball Institute of Biomolecular Medicine, Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, 550 First Ave, New York, NY, 10016, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute and Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Seattle, WA, 98109, USA.
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26
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Ranjan R, Snedeker J, Wooten M, Chu C, Bracero S, Mouton T, Chen X. Differential condensation of sister chromatids acts with Cdc6 to ensure asynchronous S-phase entry in Drosophila male germline stem cell lineage. Dev Cell 2022; 57:1102-1118.e7. [PMID: 35483360 PMCID: PMC9134767 DOI: 10.1016/j.devcel.2022.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 01/16/2022] [Accepted: 04/05/2022] [Indexed: 01/06/2023]
Abstract
During Drosophila melanogaster male germline stem cell (GSC) asymmetric division, preexisting old versus newly synthesized histones H3 and H4 are asymmetrically inherited. However, the biological outcomes of this phenomenon have remained unclear. Here, we tracked old and new histones throughout the GSC cell cycle through the use of high spatial and temporal resolution microscopy. We found unique features that differ between old and new histone-enriched sister chromatids, including differences in nucleosome density, chromosomal condensation, and H3 Ser10 phosphorylation. These distinct chromosomal features lead to their differential association with Cdc6, a pre-replication complex component, and subsequent asynchronous DNA replication initiation in the resulting daughter cells. Disruption of asymmetric histone inheritance abolishes differential Cdc6 association and asynchronous S-phase entry, demonstrating that histone asymmetry acts upstream of these critical cell-cycle progression events. Furthermore, disruption of these GSC-specific chromatin features leads to GSC defects, indicating a connection between histone inheritance, cell-cycle progression, and cell fate determination.
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Affiliation(s)
- Rajesh Ranjan
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Jonathan Snedeker
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Matthew Wooten
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Carolina Chu
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sabrina Bracero
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Taylar Mouton
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Xin Chen
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
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27
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Shindo Y, Brown MG, Amodeo AA. Versatile roles for histones in early development. Curr Opin Cell Biol 2022; 75:102069. [PMID: 35279563 PMCID: PMC9064922 DOI: 10.1016/j.ceb.2022.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/30/2022] [Accepted: 02/04/2022] [Indexed: 11/28/2022]
Abstract
The nuclear environment changes dramatically over the course of early development. Histones are core chromatin components that play critical roles in regulating gene expression and nuclear architecture. Additionally, the embryos of many species, including Drosophila, Zebrafish, and Xenopus use the availability of maternally deposited histones to time critical early embryonic events including cell cycle slowing and zygotic genome activation. Here, we review recent insights into how histones control early development. We first discuss the regulation of chromatin functions through interaction of histones and transcription factors, incorporation of variant histones, and histone post-translational modifications. We also highlight emerging roles for histones as developmental regulators independent of chromatin association.
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Affiliation(s)
- Yuki Shindo
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
| | - Madeleine G Brown
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Amanda A Amodeo
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
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28
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Razmi K, Patil JG. Primordial Germ Cell Development in the Poeciliid, Gambusia holbrooki, Reveals Shared Features Between Lecithotrophs and Matrotrophs. Front Cell Dev Biol 2022; 10:793498. [PMID: 35300414 PMCID: PMC8920993 DOI: 10.3389/fcell.2022.793498] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 01/03/2022] [Indexed: 12/02/2022] Open
Abstract
Metazoans exhibit two modes of primordial germ cell (PGC) specification that are interspersed across taxa. However, the evolutionary link between the two modes and the reproductive strategies of lecithotrophy and matrotrophy is poorly understood. As a first step to understand this, the spatio-temporal expression of teleostean germ plasm markers was investigated in Gambusia holbrooki, a poecilid with shared lecitho- and matrotrophy. A group of germ plasm components was detected in the ovum suggesting maternal inheritance mode of PGC specification. However, the strictly zygotic activation of dnd-β and nanos1 occurred relatively early, reminiscent of models with induction mode (e.g., mice). The PGC clustering, migration and colonisation patterns of G. holbrooki resembled those of zebrafish, medaka and mice at blastula, gastrula and somitogenesis, respectively—recapitulating features of advancing evolutionary nodes with progressive developmental stages. Moreover, the expression domains of PGC markers in G. holbrooki were either specific to teleost (vasa expression in developing PGCs), murine models (dnd spliced variants) or shared between the two taxa (germline and somatic expression of piwi and nanos1). Collectively, the results suggest that the reproductive developmental adaptations may reflect a transition from lecithotrophy to matrotrophy.
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Affiliation(s)
- Komeil Razmi
- Laboratory of Molecular Biology, Fisheries and Aquaculture Centre, Institute for Marine and Antarctic Studies, University of Tasmania, Taroona, TAS, Australia
| | - Jawahar G Patil
- Laboratory of Molecular Biology, Fisheries and Aquaculture Centre, Institute for Marine and Antarctic Studies, University of Tasmania, Taroona, TAS, Australia
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29
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Miao L, Tang Y, Bonneau AR, Chan SH, Kojima ML, Pownall ME, Vejnar CE, Gao F, Krishnaswamy S, Hendry CE, Giraldez AJ. The landscape of pioneer factor activity reveals the mechanisms of chromatin reprogramming and genome activation. Mol Cell 2022; 82:986-1002.e9. [PMID: 35182480 PMCID: PMC9327391 DOI: 10.1016/j.molcel.2022.01.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 01/25/2022] [Accepted: 01/26/2022] [Indexed: 10/19/2022]
Abstract
Upon fertilization, embryos undergo chromatin reprogramming and genome activation; however, the mechanisms that regulate these processes are poorly understood. Here, we generated a triple mutant for Nanog, Pou5f3, and Sox19b (NPS) in zebrafish and found that NPS pioneer chromatin opening at >50% of active enhancers. NPS regulate acetylation across core histones at enhancers and promoters, and their function in gene activation can be bypassed by recruiting histone acetyltransferase to individual genes. NPS pioneer chromatin opening individually, redundantly, or additively depending on sequence context, and we show that high nucleosome occupancy facilitates NPS pioneering activity. Nucleosome position varies based on the input of different transcription factors (TFs), providing a flexible platform to modulate pioneering activity. Altogether, our results illuminate the sequence of events during genome activation and offer a conceptual framework to understand how pioneer factors interpret the genome and integrate different TF inputs across cell types and developmental transitions.
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Affiliation(s)
- Liyun Miao
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA.
| | - Yin Tang
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Ashley R Bonneau
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Shun Hang Chan
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Mina L Kojima
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Mark E Pownall
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Charles E Vejnar
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Feng Gao
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Smita Krishnaswamy
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Computer Science, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Caroline E Hendry
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Antonio J Giraldez
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA; Yale Stem Cell Center, Yale University School of Medicine, New Haven, CT 06510, USA; Yale Cancer Center, Yale University School of Medicine, New Haven, CT 06510, USA.
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30
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Pluripotency factors determine gene expression repertoire at zygotic genome activation. Nat Commun 2022; 13:788. [PMID: 35145080 PMCID: PMC8831532 DOI: 10.1038/s41467-022-28434-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 01/24/2022] [Indexed: 12/28/2022] Open
Abstract
Awakening 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 analyze chromatin accessibility and time-resolved transcription in single and double mutant zebrafish embryos lacking pluripotency factors Pou5f3 and Sox19b. We show that two factors modify chromatin in a largely independent manner. We distinguish four types of direct enhancers by differential requirements for Pou5f3 or Sox19b. We demonstrate that changes in chromatin accessibility of enhancers underlie the changes in zygotic expression repertoire in the double mutants. Pou5f3 or Sox19b promote chromatin accessibility of enhancers linked to the genes involved in gastrulation and ventral fate specification. The genes regulating mesendodermal and dorsal fates are primed for activation independently of Pou5f3 and Sox19b. Strikingly, simultaneous loss of Pou5f3 and Sox19b leads to premature expression of genes, involved in regulation of organogenesis and differentiation. Zygotic genome activation in zebrafish relies on pluripotency transcription factors Pou5f3 and Sox19b. Here the authors investigate how these factors interact in vivo by analyzing the changes in chromatin state and time-resolved transcription in Pou5f3 and Sox19b single and double mutant embryos.
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31
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Mircea M, Semrau S. How a cell decides its own fate: a single-cell view of molecular mechanisms and dynamics of cell-type specification. Biochem Soc Trans 2021; 49:2509-2525. [PMID: 34854897 PMCID: PMC8786291 DOI: 10.1042/bst20210135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/06/2021] [Accepted: 11/08/2021] [Indexed: 12/13/2022]
Abstract
On its path from a fertilized egg to one of the many cell types in a multicellular organism, a cell turns the blank canvas of its early embryonic state into a molecular profile fine-tuned to achieve a vital organismal function. This remarkable transformation emerges from the interplay between dynamically changing external signals, the cell's internal, variable state, and tremendously complex molecular machinery; we are only beginning to understand. Recently developed single-cell omics techniques have started to provide an unprecedented, comprehensive view of the molecular changes during cell-type specification and promise to reveal the underlying gene regulatory mechanism. The exponentially increasing amount of quantitative molecular data being created at the moment is slated to inform predictive, mathematical models. Such models can suggest novel ways to manipulate cell types experimentally, which has important biomedical applications. This review is meant to give the reader a starting point to participate in this exciting phase of molecular developmental biology. We first introduce some of the principal molecular players involved in cell-type specification and discuss the important organizing ability of biomolecular condensates, which has been discovered recently. We then review some of the most important single-cell omics methods and relevant findings they produced. We devote special attention to the dynamics of the molecular changes and discuss methods to measure them, most importantly lineage tracing. Finally, we introduce a conceptual framework that connects all molecular agents in a mathematical model and helps us make sense of the experimental data.
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Affiliation(s)
- Maria Mircea
- Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - Stefan Semrau
- Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
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32
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Histone variant H2A.Z regulates zygotic genome activation. Nat Commun 2021; 12:7002. [PMID: 34853314 PMCID: PMC8636486 DOI: 10.1038/s41467-021-27125-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/28/2021] [Indexed: 12/13/2022] Open
Abstract
During embryogenesis, the genome shifts from transcriptionally quiescent to extensively active in a process known as Zygotic Genome Activation (ZGA). In Drosophila, the pioneer factor Zelda is known to be essential for the progression of development; still, it regulates the activation of only a small subset of genes at ZGA. However, thousands of genes do not require Zelda, suggesting that other mechanisms exist. By conducting GRO-seq, HiC and ChIP-seq in Drosophila embryos, we demonstrate that up to 65% of zygotically activated genes are enriched for the histone variant H2A.Z. H2A.Z enrichment precedes ZGA and RNA Polymerase II loading onto chromatin. In vivo knockdown of maternally contributed Domino, a histone chaperone and ATPase, reduces H2A.Z deposition at transcription start sites, causes global downregulation of housekeeping genes at ZGA, and compromises the establishment of the 3D chromatin structure. We infer that H2A.Z is essential for the de novo establishment of transcriptional programs during ZGA via chromatin reorganization. During embryogenesis, the genome becomes transcriptionally active in a process known as zygotic genome activation (ZGA); how ZGA is initiated is still an open question. Here the authors show histone variant H2A.Z deposition precedes RNA polymerase II binding on chromatin, before ZGA. H2A.Z loss causes transcriptional downregulation of ZGA genes and leads to changes in the 3D genome organization.
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33
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Pancholi A, Klingberg T, Zhang W, Prizak R, Mamontova I, Noa A, Sobucki M, Kobitski AY, Nienhaus GU, Zaburdaev V, Hilbert L. RNA polymerase II clusters form in line with surface condensation on regulatory chromatin. Mol Syst Biol 2021; 17:e10272. [PMID: 34569155 PMCID: PMC8474054 DOI: 10.15252/msb.202110272] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 08/26/2021] [Accepted: 09/10/2021] [Indexed: 12/15/2022] Open
Abstract
It is essential for cells to control which genes are transcribed into RNA. In eukaryotes, two major control points are recruitment of RNA polymerase II (Pol II) into a paused state, and subsequent pause release toward transcription. Pol II recruitment and pause release occur in association with macromolecular clusters, which were proposed to be formed by a liquid-liquid phase separation mechanism. How such a phase separation mechanism relates to the interaction of Pol II with DNA during recruitment and transcription, however, remains poorly understood. Here, we use live and super-resolution microscopy in zebrafish embryos to reveal Pol II clusters with a large variety of shapes, which can be explained by a theoretical model in which regulatory chromatin regions provide surfaces for liquid-phase condensation at concentrations that are too low for canonical liquid-liquid phase separation. Model simulations and chemical perturbation experiments indicate that recruited Pol II contributes to the formation of these surface-associated condensates, whereas elongating Pol II is excluded from these condensates and thereby drives their unfolding.
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Affiliation(s)
- Agnieszka Pancholi
- Zoological InstituteDepartment of Systems Biology and BioinformaticsKarlsruhe Institute of TechnologyKarlsruheGermany
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Tim Klingberg
- Department of BiologyFriedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
- Max‐Planck‐Zentrum für Physik und MedizinErlangenGermany
| | - Weichun Zhang
- Institute of Applied PhysicsKarlsruhe Institute of TechnologyKarlsruheGermany
- Institute of NanotechnologyKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Roshan Prizak
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Irina Mamontova
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Amra Noa
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Marcel Sobucki
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Andrei Yu Kobitski
- Institute of Applied PhysicsKarlsruhe Institute of TechnologyKarlsruheGermany
| | - Gerd Ulrich Nienhaus
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
- Institute of Applied PhysicsKarlsruhe Institute of TechnologyKarlsruheGermany
- Institute of NanotechnologyKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
- Department of PhysicsUniversity of Illinois at Urbana‐ChampaignUrbanaILUSA
| | - Vasily Zaburdaev
- Department of BiologyFriedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
- Max‐Planck‐Zentrum für Physik und MedizinErlangenGermany
| | - Lennart Hilbert
- Zoological InstituteDepartment of Systems Biology and BioinformaticsKarlsruhe Institute of TechnologyKarlsruheGermany
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
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34
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Cell division geometries as central organizers of early embryo development. Semin Cell Dev Biol 2021; 130:3-11. [PMID: 34419349 DOI: 10.1016/j.semcdb.2021.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/08/2021] [Indexed: 11/24/2022]
Abstract
Early cellular patterning is a critical step of embryonic development that determines the proper progression of morphogenesis in all metazoans. It relies on a series of rapid reductive divisions occurring simultaneously with the specification of the fate of different subsets of cells. Multiple species developmental strategies emerged in the form of a unique cleavage pattern with stereotyped division geometries. Cleavage geometries have long been associated to the emergence of canonical developmental features such as cell cycle asynchrony, zygotic genome activation and fate specification. Yet, the direct causal role of division positioning on blastomere cell behavior remain partially understood. Oriented and/or asymmetric divisions define blastomere cell sizes, contacts and positions, with potential immediate impact on cellular decisions, lineage specification and morphogenesis. Division positions also instruct daughter cells polarity, mechanics and geometries, thereby influencing subsequent division events, in an emergent interplay that may pattern early embryos independently of firm deterministic genetic programs. We here review the recent literature which helped to delineate mechanisms and functions of division positioning in early embryos.
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35
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Jukam D, Kapoor RR, Straight AF, Skotheim JM. The DNA-to-cytoplasm ratio broadly activates zygotic gene expression in Xenopus. Curr Biol 2021; 31:4269-4281.e8. [PMID: 34388374 DOI: 10.1016/j.cub.2021.07.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/13/2021] [Accepted: 07/14/2021] [Indexed: 10/20/2022]
Abstract
In multicellular animals, the first major event after fertilization is the switch from maternal to zygotic control of development. During this transition, zygotic gene transcription is broadly activated in an otherwise quiescent genome in a process known as zygotic genome activation (ZGA). In fast-developing embryos, ZGA often overlaps with the slowing of initially synchronous cell divisions at the mid-blastula transition (MBT). Initial studies of the MBT led to the nuclear-to-cytoplasmic ratio model where MBT timing is regulated by the exponentially increasing amounts of some nuclear component "N" titrated against a fixed cytoplasmic component "C." However, more recent experiments have been interpreted to suggest that ZGA is independent of the N/C ratio. To determine the role of the N/C ratio in ZGA, we generated Xenopus frog embryos with ∼3-fold differences in genomic DNA (i.e., N) by using X. tropicalis sperm to fertilize X. laevis eggs with or without their maternal genome. Resulting embryos have otherwise identical X. tropicalis genome template amounts, embryo sizes, and X. laevis maternal environments. We generated transcriptomic time series across the MBT in both conditions and used X. tropicalis paternally derived mRNA to identify a high-confidence set of exclusively zygotic transcripts. Both ZGA and the increase in cell-cycle duration are delayed in embryos with ∼3-fold less DNA per cell. Thus, DNA is an important component of the N/C ratio, which is a critical regulator of zygotic genome activation in Xenopus embryos.
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Affiliation(s)
- David Jukam
- Department of Biology, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Rishabh R Kapoor
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Aaron F Straight
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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Claude KL, Bureik D, Chatzitheodoridou D, Adarska P, Singh A, Schmoller KM. Transcription coordinates histone amounts and genome content. Nat Commun 2021; 12:4202. [PMID: 34244507 PMCID: PMC8270936 DOI: 10.1038/s41467-021-24451-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 06/18/2021] [Indexed: 02/06/2023] Open
Abstract
Biochemical reactions typically depend on the concentrations of the molecules involved, and cell survival therefore critically depends on the concentration of proteins. To maintain constant protein concentrations during cell growth, global mRNA and protein synthesis rates are tightly linked to cell volume. While such regulation is appropriate for most proteins, certain cellular structures do not scale with cell volume. The most striking example of this is the genomic DNA, which doubles during the cell cycle and increases with ploidy, but is independent of cell volume. Here, we show that the amount of histone proteins is coupled to the DNA content, even though mRNA and protein synthesis globally increase with cell volume. As a consequence, and in contrast to the global trend, histone concentrations decrease with cell volume but increase with ploidy. We find that this distinct coordination of histone homeostasis and genome content is already achieved at the transcript level, and is an intrinsic property of histone promoters that does not require direct feedback mechanisms. Mathematical modeling and histone promoter truncations reveal a simple and generalizable mechanism to control the cell volume- and ploidy-dependence of a given gene through the balance of the initiation and elongation rates.
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Affiliation(s)
- Kora-Lee Claude
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Daniela Bureik
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany
| | | | - Petia Adarska
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Abhyudai Singh
- Department of Electrical & Computer Engineering, University of Delaware, Newark, DE, USA
| | - Kurt M Schmoller
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany.
- German Center for Diabetes Research (DZD), Neuherberg, Germany.
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Abstract
Understanding the mechanisms of embryonic cell cycles is a central goal of developmental biology, as the regulation of the cell cycle must be closely coordinated with other events during early embryogenesis. Quantitative imaging approaches have recently begun to reveal how the cell cycle oscillator is controlled in space and time, and how it is integrated with mechanical signals to drive morphogenesis. Here, we discuss how the Drosophila embryo has served as an excellent model for addressing the molecular and physical mechanisms of embryonic cell cycles, with comparisons to other model systems to highlight conserved and species-specific mechanisms. We describe how the rapid cleavage divisions characteristic of most metazoan embryos require chemical waves and cytoplasmic flows to coordinate morphogenesis across the large expanse of the embryo. We also outline how, in the late cleavage divisions, the cell cycle is inter-regulated with the activation of gene expression to ensure a reliable maternal-to-zygotic transition. Finally, we discuss how precise transcriptional regulation of the timing of mitosis ensures that tissue morphogenesis and cell proliferation are tightly controlled during gastrulation.
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Affiliation(s)
| | - Stefano Di Talia
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27705, USA
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38
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Liu B, Zhao H, Wu K, Großhans J. Temporal Gradients Controlling Embryonic Cell Cycle. BIOLOGY 2021; 10:biology10060513. [PMID: 34207742 PMCID: PMC8228447 DOI: 10.3390/biology10060513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/05/2021] [Accepted: 06/07/2021] [Indexed: 12/17/2022]
Abstract
Simple Summary Embryonic cells sense temporal gradients of regulatory signals to determine whether and when to proceed or remodel the cell cycle. Such a control mechanism is allowed to accurately link the cell cycle with the developmental program, including cell differentiation, morphogenesis, and gene expression. The mid-blastula transition has been a paradigm for timing in early embryogenesis in frog, fish, and fly, among others. It has been argued for decades now if the events associated with the mid-blastula transition, i.e., the onset of zygotic gene expression, remodeling of the cell cycle, and morphological changes, are determined by a control mechanism or by absolute time. Recent studies indicate that multiple independent signals and mechanisms contribute to the timing of these different processes. Here, we focus on the mechanisms for cell cycle remodeling, specifically in Drosophila, which relies on gradual changes of the signal over time. We discuss pathways for checkpoint activation, decay of Cdc25 protein levels, as well as depletion of deoxyribonucleotide metabolites and histone proteins. The gradual changes of these signals are linked to Cdk1 activity by readout mechanisms involving thresholds. Abstract Cell proliferation in early embryos by rapid cell cycles and its abrupt pause after a stereotypic number of divisions present an attractive system to study the timing mechanism in general and its coordination with developmental progression. In animals with large eggs, such as Xenopus, zebrafish, or Drosophila, 11–13 very fast and synchronous cycles are followed by a pause or slowdown of the cell cycle. The stage when the cell cycle is remodeled falls together with changes in cell behavior and activation of the zygotic genome and is often referred to as mid-blastula transition. The number of fast embryonic cell cycles represents a clear and binary readout of timing. Several factors controlling the cell cycle undergo dynamics and gradual changes in activity or concentration and thus may serve as temporal gradients. Recent studies have revealed that the gradual loss of Cdc25 protein, gradual depletion of free deoxyribonucleotide metabolites, or gradual depletion of free histone proteins impinge on Cdk1 activity in a threshold-like manner. In this review, we will highlight with a focus on Drosophila studies our current understanding and recent findings on the generation and readout of these temporal gradients, as well as their position within the regulatory network of the embryonic cell cycle.
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Affiliation(s)
- Boyang Liu
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan 250012, China; (B.L.); (H.Z.); (K.W.)
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan 250012, China
| | - Han Zhao
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan 250012, China; (B.L.); (H.Z.); (K.W.)
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan 250012, China
| | - Keliang Wu
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan 250012, China; (B.L.); (H.Z.); (K.W.)
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan 250012, China
| | - Jörg Großhans
- Department of Biology, Philipps University, 35043 Marburg, Germany
- Correspondence:
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Modeling the role for nuclear import dynamics in the early embryonic cell cycle. Biophys J 2021; 120:4277-4286. [PMID: 34022240 DOI: 10.1016/j.bpj.2021.05.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/22/2021] [Accepted: 05/06/2021] [Indexed: 11/21/2022] Open
Abstract
Nuclear composition determines nuclear function. The early embryos of many species begin life with large pools of maternally provided components that become rapidly imported into an increasing number of nuclei as the cells undergo repeated cleavage divisions. Because early cell cycles are too fast for nuclei to achieve steady-state nucleocytoplasmic partitioning, the composition of cleavage stage nuclei is likely dominated by nuclear import. The end of the rapid cleavage stage and onset of major zygotic transcription, known as the mid-blastula transition (MBT), is controlled by the ratio of nuclei/cytoplasm, indicating that changes in nuclear composition likely mediate MBT timing. Here, we explore how different nuclear import regimes can affect protein accumulation in the nucleus in the early Drosophila embryo. We find that nuclear import differs dramatically for a general nuclear cargo (NLS (nuclear localization signal)-mRFP) and a proposed MBT regulator (histone H3). We show that nuclear import rates of NLS-mRFP in a given nucleus remain relatively unchanged throughout the cleavage cycles, whereas those of H3 halve with each cycle. We model these two distinct modes of nuclear import as "nucleus-limited" and "import-limited" and examine how the two different modes can contribute to different protein accumulation dynamics. Finally, we incorporate these distinct modes of nuclear import into a model for cell-cycle regulation at the MBT and find that the import-limited H3 dynamics contribute to increased robustness and allow for stepwise cell-cycle slowing at the MBT.
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Shindo Y, Amodeo AA. Excess histone H3 is a competitive Chk1 inhibitor that controls cell-cycle remodeling in the early Drosophila embryo. Curr Biol 2021; 31:2633-2642.e6. [PMID: 33848457 DOI: 10.1016/j.cub.2021.03.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/08/2021] [Accepted: 03/10/2021] [Indexed: 12/31/2022]
Abstract
The DNA damage checkpoint is crucial to protect genome integrity.1,2 However, the early embryos of many metazoans sacrifice this safeguard to allow for rapid cleavage divisions that are required for speedy development. At the mid-blastula transition (MBT), embryos switch from rapid cleavage divisions to slower, patterned divisions with the addition of gap phases and acquisition of DNA damage checkpoints. The timing of the MBT is dependent on the nuclear-to-cytoplasmic (N/C ratio)3-7 and the activation of the checkpoint kinase, Chk1.8-17 How Chk1 activity is coupled to the N/C ratio has remained poorly understood. Here, we show that dynamic changes in histone H3 availability in response to the increasing N/C ratio control Chk1 activity and thus time the MBT in the Drosophila embryo. We show that excess H3 in the early cycles interferes with cell-cycle slowing independent of chromatin incorporation. We find that the N-terminal tail of H3 acts as a competitive inhibitor of Chk1 in vitro and reduces Chk1 activity in vivo. Using a H3-tail mutant that has reduced Chk1 inhibitor activity, we show that the amount of available Chk1 sites in the H3 pool controls the dynamics of cell-cycle progression. Mathematical modeling quantitatively supports a mechanism where titration of H3 during early cleavage cycles regulates Chk1-dependent cell-cycle slowing. This study defines Chk1 regulation by H3 as a key mechanism that coordinates cell-cycle remodeling with developmental progression.
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Affiliation(s)
- Yuki Shindo
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Amanda A Amodeo
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
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41
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Liu S, Deng X, Bai L. Developmental toxicity and transcriptome analysis of zebrafish (Danio rerio) embryos following exposure to chiral herbicide safener benoxacor. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 761:143273. [PMID: 33190894 DOI: 10.1016/j.scitotenv.2020.143273] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/17/2020] [Accepted: 10/22/2020] [Indexed: 06/11/2023]
Abstract
Benoxacor, a chiral herbicide safener for S-metolachlor, has been detected in streams. However, the potential risk this poses to aquatic ecosystems is not clear. This study used zebrafish (Danio rerio) embryos as a model to assess the enantioselective toxicity of benoxacor and its effects on biological activity and development from 2 h to 96 h post-fertilization (hpf). Results showed that benoxacor had negative effects on hatchability, malformations, and mortality. Compared to either individual enantiomer, embryos exposed to Rac-benoxacor had higher acute and developmental toxicities, glutathione S-transferase (GST) and glutathione peroxidase (GPx) enzyme activities, and nrf 2 expression levels. They also had lower superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR) enzyme activity and krt 17, tbx 16, osx, cat, bcl 2, bax, and ifn expression levels. High-throughput RNA sequencing revealed that Rac-benoxacor had a greater effect on gene regulation than either enantiomer. Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses demonstrated that changes in oxidoreductase activity, cellular lipid metabolic process, and catalytic activity related genes may be due to the enantioselective effects of benoxacor isomers. These results suggest that the ecotoxicology data and safety knowledge about the effects of chiral benoxacor on zebrafish should be considered in future environmental risk evaluation.
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Affiliation(s)
- Sihong Liu
- Key Laboratory for Biology and Control of Weeds, Biotechnology Research Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China; Long Ping Branch, Graduate School of Hunan University, Changsha 410125, China
| | - Xile Deng
- Key Laboratory for Biology and Control of Weeds, Biotechnology Research Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China.
| | - Lianyang Bai
- Key Laboratory for Biology and Control of Weeds, Biotechnology Research Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China; Long Ping Branch, Graduate School of Hunan University, Changsha 410125, China.
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42
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Abstract
In eukaryotes, DNA is packed inside the cell nucleus in the form of chromatin, which consists of DNA, proteins such as histones, and RNA. Euchromatin, which is permissive for transcription, is spatially organized into transcriptionally inactive domains interspersed with pockets of transcriptional activity. While transcription and RNA have been implicated in euchromatin organization, it remains unclear how their interplay forms and maintains transcription pockets. Here we combine theory and experiment to analyze the dynamics of euchromatin organization as pluripotent zebrafish cells exit mitosis and begin transcription. We show that accumulation of RNA induces formation of transcription pockets which displace transcriptionally inactive chromatin. We propose that the accumulating RNA recruits RNA-binding proteins that together tend to separate from transcriptionally inactive euchromatin. Full phase separation is prevented because RNA remains tethered to transcribed euchromatin through RNA polymerases. Instead, smaller scale microphases emerge that do not grow further and form the typical pattern of euchromatin organization.
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Abstract
In the past several decades, the establishment of in vitro models of pluripotency has ushered in a golden era for developmental and stem cell biology. Research in this arena has led to profound insights into the regulatory features that shape early embryonic development. Nevertheless, an integrative theory of the epigenetic principles that govern the pluripotent nucleus remains elusive. Here, we summarize the epigenetic characteristics that define the pluripotent state. We cover what is currently known about the epigenome of pluripotent stem cells and reflect on the use of embryonic stem cells as an experimental system. In addition, we highlight insights from super-resolution microscopy, which have advanced our understanding of the form and function of chromatin, particularly its role in establishing the characteristically "open chromatin" of pluripotent nuclei. Further, we discuss the rapid improvements in 3C-based methods, which have given us a means to investigate the 3D spatial organization of the pluripotent genome. This has aided the adaptation of prior notions of a "pluripotent molecular circuitry" into a more holistic model, where hotspots of co-interacting domains correspond with the accumulation of pluripotency-associated factors. Finally, we relate these earlier hypotheses to an emerging model of phase separation, which posits that a biophysical mechanism may presuppose the formation of a pluripotent-state-defining transcriptional program.
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Affiliation(s)
| | - Eran Meshorer
- Department of Genetics, the Institute of Life Sciences
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel 9190400
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44
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Abstract
The fertilized frog egg contains all the materials needed to initiate development of a new organism, including stored RNAs and proteins deposited during oogenesis, thus the earliest stages of development do not require transcription. The onset of transcription from the zygotic genome marks the first genetic switch activating the gene regulatory network that programs embryonic development. Zygotic genome activation occurs after an initial phase of transcriptional quiescence that continues until the midblastula stage, a period called the midblastula transition, which was first identified in Xenopus. Activation of transcription is programmed by maternally supplied factors and is regulated at multiple levels. A similar switch exists in most animals and is of great interest both to developmental biologists and to those interested in understanding nuclear reprogramming. Here we review in detail our knowledge on this major switch in transcription in Xenopus and place recent discoveries in the context of a decades old problem.
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45
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Chen H, Qian W, Good MC. Integrating cellular dimensions with cell differentiation during early development. Curr Opin Cell Biol 2020; 67:109-117. [PMID: 33152556 DOI: 10.1016/j.ceb.2020.08.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 07/14/2020] [Accepted: 08/03/2020] [Indexed: 11/25/2022]
Abstract
Early embryo development is characterized by alteration of cellular dimensions and fating of blastomeres. An emerging concept is that cell size and shape drive cellular differentiation during early embryogenesis in a variety of model organisms. In this review, we summarize recent advances that elucidate the contribution of the physical dimensions of a cell to major embryonic transitions and cell fate specification in vivo. We also highlight techniques and newly evolving methods for manipulating the sizes and shapes of cells and whole embryos in situ and ex vivo. Finally, we provide an outlook for addressing fundamental questions in the field and more broadly uncovering how changes to cell size control decision making in a variety of biological contexts.
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Affiliation(s)
- Hui Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Wenchao Qian
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew C Good
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA.
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46
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Malousi A, Andreou AZ, Kouidou S. In silico structural analysis of sequences containing 5-hydroxymethylcytosine reveals its potential as binding regulator for development, ageing and cancer-related transcription factors. Epigenetics 2020; 16:503-518. [PMID: 32752914 DOI: 10.1080/15592294.2020.1805693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The presence of 5-hydroxymethyl cytosine in DNA has been previously associated with ageing. Using in silico analysis of normal liver samples we presently observed that in 5-hydroxymethyl cytosine sequences, DNA methylation is dependent on the co-presence of G-quadruplexes and palindromes. This association exhibits discrete patterns depending on G-quadruplex and palindrome densities. DNase-Seq data show that 5-hydroxymethyl cytosine sequences are common among liver nucleosomes (p < 2.2x10-16) and threefold more frequent than nucleosome sequences. Nucleosomes lacking palindromes and potential G-quadruplexes are rare in vivo (1%) and nucleosome occupancy potential decreases with increasing G-quadruplexes. Palindrome distribution is similar to that previously reported in nucleosomes. In low and mixed complexity sequences 5-hydroxymethyl cytosine is frequently located next to three elements: G-quadruplexes or imperfect G-quadruplexes with CpGs, or unstable hairpin loops (TCCCAY6TGGGA) mostly located in antisense strands or finally A-/T-rich segments near these motifs. The high frequencies and selective distribution of pentamer sequences (including TCCCA, TGGGA) probably indicate the positive contribution of 5-hydroxymethyl cytosine to stabilize the formation of structures unstable in the absence of this cytosine modification. Common motifs identified in all total 5-hydroxymethyl cytosine-containing sequences exhibit high homology to recognition sites of several transcription factor families: homeobox, factors involved in growth, mortality/ageing, cancer, neuronal function, vision, and reproduction. We conclude that cytosine hydroxymethylation could play a role in the recognition of sequences with G-quadruplexes/palindromes by forming epigenetically regulated DNA 'springs' and governing expansions or compressions recognized by different transcription factors or stabilizing nucleosomes. The balance of these epigenetic elements is lost in hepatocellular carcinoma.
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Affiliation(s)
- Andigoni Malousi
- Lab. of Biological Chemistry, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Sofia Kouidou
- Lab. of Biological Chemistry, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
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47
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Paraiso KD, Blitz IL, Coley M, Cheung J, Sudou N, Taira M, Cho KWY. Endodermal Maternal Transcription Factors Establish Super-Enhancers during Zygotic Genome Activation. Cell Rep 2020; 27:2962-2977.e5. [PMID: 31167141 PMCID: PMC6610736 DOI: 10.1016/j.celrep.2019.05.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 03/30/2019] [Accepted: 05/01/2019] [Indexed: 01/06/2023] Open
Abstract
Elucidation of the sequence of events underlying the dynamic interaction
between transcription factors and chromatin states is essential. Maternal
transcription factors function at the top of the regulatory hierarchy to specify
the primary germ layers at the onset of zygotic genome activation (ZGA). We
focus on the formation of endoderm progenitor cells and examine the interactions
between maternal transcription factors and chromatin state changes underlying
the cell specification process. Endoderm-specific factors Otx1 and Vegt together
with Foxh1 orchestrate endoderm formation by coordinated binding to select
regulatory regions. These interactions occur before the deposition of enhancer
histone marks around the regulatory regions, and these TFs recruit RNA
polymerase II, regulate enhancer activity, and establish super-enhancers
associated with important endodermal genes. Therefore, maternal transcription
factors Otx1, Vegt, and Foxh1 combinatorially regulate the activity of
super-enhancers, which in turn activate key lineage-specifying genes during
ZGA. How do maternal transcription factors interact with chromatin regions to
coordinate the endodermal gene regulatory program? Paraiso et al. demonstrate
that combinatorial binding of maternal Otx1, Vegt, and Foxh1 to select enhancers
and super-enhancers in the genome controls endodermal cell fate specification
during zygotic gene activation.
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Affiliation(s)
- Kitt D Paraiso
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA; Center for Complex Biological Systems, University of California, Irvine, CA, USA
| | - Ira L Blitz
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Masani Coley
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Jessica Cheung
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA
| | - Norihiro Sudou
- Department of Anatomy, Tokyo Women's Medical University, Tokyo, Japan
| | - Masanori Taira
- Department of Biological Sciences, Chuo University, Tokyo, Japan
| | - Ken W Y Cho
- Department of Developmental and Cell Biology, University of California, Irvine, CA, USA; Center for Complex Biological Systems, University of California, Irvine, CA, USA.
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48
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Karpukhina A, Vassetzky Y. DUX4, a Zygotic Genome Activator, Is Involved in Oncogenesis and Genetic Diseases. Russ J Dev Biol 2020. [DOI: 10.1134/s1062360420030078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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49
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Cavalieri V. Histones, Their Variants and Post-translational Modifications in Zebrafish Development. Front Cell Dev Biol 2020; 8:456. [PMID: 32582716 PMCID: PMC7289917 DOI: 10.3389/fcell.2020.00456] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 05/15/2020] [Indexed: 01/01/2023] Open
Abstract
Complex multi-cellular organisms are shaped starting from a single-celled zygote, owing to elaborate developmental programs. These programs involve several layers of regulation to orchestrate the establishment of progressively diverging cell type-specific gene expression patterns. In this scenario, epigenetic modifications of chromatin are central in influencing spatiotemporal patterns of gene transcription. In fact, it is generally recognized that epigenetic changes of chromatin states impact on the accessibility of genomic DNA to regulatory proteins. Several lines of evidence highlighted that zebrafish is an excellent vertebrate model for research purposes in the field of developmental epigenetics. In this review, I focus on the dynamic roles recently emerged for histone post-translational modifications (PTMs), histone modifying enzymes, histone variants and histone themselves in the coordination between the precise execution of transcriptional programs and developmental progression in zebrafish. In particular, I first outline a synopsis of the current state of knowledge in this field during early embryogenesis. Then, I present a survey of histone-based epigenetic mechanisms occurring throughout morphogenesis, with a stronger emphasis on cardiac formation. Undoubtedly, the issues addressed in this review take on particular importance in the emerging field of comparative biology of epigenetics, as well as in translational research.
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Affiliation(s)
- Vincenzo Cavalieri
- Laboratory of Molecular Biology and Functional Genomics, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Palermo, Italy.,Zebrafish Laboratory, Advanced Technologies Network (ATeN) Center, University of Palermo, Palermo, Italy
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50
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Akdogan-Ozdilek B, Duval KL, Goll MG. Chromatin dynamics at the maternal to zygotic transition: recent advances from the zebrafish model. F1000Res 2020; 9. [PMID: 32528656 PMCID: PMC7262572 DOI: 10.12688/f1000research.21809.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/17/2020] [Indexed: 01/02/2023] Open
Abstract
Early animal development is characterized by intense reorganization of the embryonic genome, including large-scale changes in chromatin structure and in the DNA and histone modifications that help shape this structure. Particularly profound shifts in the chromatin landscape are associated with the maternal-to-zygotic transition, when the zygotic genome is first transcribed and maternally loaded transcripts are degraded. The accessibility of the early zebrafish embryo facilitates the interrogation of chromatin during this critical window of development, making it an important model for early chromatin regulation. Here, we review our current understanding of chromatin dynamics during early zebrafish development, highlighting new advances as well as similarities and differences between early chromatin regulation in zebrafish and other species.
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Affiliation(s)
| | | | - Mary G Goll
- Department of Genetics, University of Georgia, Athens, GA, USA
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