scholarly journals Epigenetic regulation of the histone-to-protamine transition during spermiogenesis

Reproduction ◽  
2016 ◽  
Vol 151 (5) ◽  
pp. R55-R70 ◽  
Author(s):  
Jianqiang Bao ◽  
Mark T Bedford
Keyword(s):  
Transcription Factors ◽  
Germ Cells ◽  
Transition Process ◽  
Histone Variants ◽  
Motile Sperm ◽  
Male Germ Cells ◽  
The Core ◽  
Developmental Program ◽  
Core Histones ◽  
Epigenetic Regulators

Abstract In mammals, male germ cells differentiate from haploid round spermatids to flagella-containing motile sperm in a process called spermiogenesis. This process is distinct from somatic cell differentiation in that the majority of the core histones are replaced sequentially, first by transition proteins and then by protamines, facilitating chromatin hyper-compaction. This histone-to-protamine transition process represents an excellent model for the investigation of how epigenetic regulators interact with each other to remodel chromatin architecture. Although early work in the field highlighted the critical roles of testis-specific transcription factors in controlling the haploid-specific developmental program, recent studies underscore the essential functions of epigenetic players involved in the dramatic genome remodeling that takes place during wholesale histone replacement. In this review, we discuss recent advances in our understanding of how epigenetic players, such as histone variants and histone writers/readers/erasers, rewire the haploid spermatid genome to facilitate histone substitution by protamines in mammals.

scholarly journals Identification and Characterization of the Genes Encoding the Core Histones and Histone Variants of Neurospora crassa

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 961-973 ◽  
Author(s):  
Shan M Hays ◽  
Johanna Swanson ◽  
Eric U Selker
Keyword(s):  
Neurospora Crassa ◽  
Histone Variants ◽  
Null Alleles ◽  
Histone Genes ◽  
Histone H4 ◽  
Coding Regions ◽  
The Core ◽  
Genomic Arrangement ◽  
Genes Encoding ◽  
Core Histones

Abstract We have identified and characterized the complete complement of genes encoding the core histones of Neurospora crassa. In addition to the previously identified pair of genes that encode histones H3 and H4 (hH3 and hH4-1), we identified a second histone H4 gene (hH4-2), a divergently transcribed pair of genes that encode H2A and H2B (hH2A and hH2B), a homolog of the F/Z family of H2A variants (hH2Az), a homolog of the H3 variant CSE4 from Saccharomyces cerevisiae (hH3v), and a highly diverged H4 variant (hH4v) not described in other species. The hH4-1 and hH4-2 genes, which are 96% identical in their coding regions and encode identical proteins, were inactivated independently. Strains with inactivating mutations in either gene were phenotypically wild type, in terms of growth rates and fertility, but the double mutants were inviable. As expected, we were unable to isolate null alleles of hH2A, hH2B, or hH3. The genomic arrangement of the histone and histone variant genes was determined. hH2Az and the hH3-hH4-1 gene pair are on LG IIR, with hH2Az centromere-proximal to hH3-hH4-1 and hH3 centromere-proximal to hH4-1. hH3v and hH4-2 are on LG IIIR with hH3v centromere-proximal to hH4-2. hH4v is on LG IVR and the hH2A-hH2B pair is located immediately right of the LG VII centromere, with hH2A centromere-proximal to hH2B. Except for the centromere-distal gene in the pairs, all of the histone genes are transcribed toward the centromere. Phylogenetic analysis of the N. crassa histone genes places them in the Euascomycota lineage. In contrast to the general case in eukaryotes, histone genes in euascomycetes are few in number and contain introns. This may be a reflection of the evolution of the RIP (repeat-induced point mutation) and MIP (methylation induced premeiotically) processes that detect sizable duplications and silence associated genes.

Histone Variants: The Nexus of Developmental Decisions and Epigenetic Memory

2020 ◽  
Vol 54 (1) ◽  
pp. 121-149 ◽  
Author(s):  
Benjamin Loppin ◽  
Frédéric Berger
Keyword(s):  
Cell Differentiation ◽  
Cell Fate ◽  
Histone Variants ◽  
Epigenetic Memory ◽  
The Core ◽  
Nucleosome Dynamics ◽  
Nucleosome Structure ◽  
Core Histones ◽  
And Function ◽  
The Impact

Nucleosome dynamics and properties are central to all forms of genomic activities. Among the core histones, H3 variants play a pivotal role in modulating nucleosome structure and function. Here, we focus on the impact of H3 variants on various facets of development. The deposition of the replicative H3 variant following DNA replication is essential for the transmission of the epigenomic information encoded in posttranscriptional modifications. Through this process, replicative H3 maintains cell fate while, in contrast, the replacement H3.3 variant opposes cell differentiation during early embryogenesis. In later steps of development, H3.3 and specialized H3 variants are emerging as new, important regulators of terminal cell differentiation, including neurons and gametes. The specific pathways that regulate the dynamics of the deposition of H3.3 are paramount during reprogramming events that drive zygotic activation and the initiation of a new cycle of development.

scholarly journals Short Histone H2A Variants: Small in Stature but not in Function

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 867 ◽  
Author(s):  
Xuanzhao Jiang ◽  
Tatiana A. Soboleva ◽  
David J. Tremethick
Keyword(s):  
Chromatin Structure ◽  
Biochemical Composition ◽  
Histone Variants ◽  
Histone H2a ◽  
The Core ◽  
Unique Protein ◽  
Core Histones ◽  
The Brain ◽  
Fundamental Mechanism ◽  
The Way

The dynamic packaging of DNA into chromatin regulates all aspects of genome function by altering the accessibility of DNA and by providing docking pads to proteins that copy, repair and express the genome. Different epigenetic-based mechanisms have been described that alter the way DNA is organised into chromatin, but one fundamental mechanism alters the biochemical composition of a nucleosome by substituting one or more of the core histones with their variant forms. Of the core histones, the largest number of histone variants belong to the H2A class. The most divergent class is the designated “short H2A variants” (H2A.B, H2A.L, H2A.P and H2A.Q), so termed because they lack a H2A C-terminal tail. These histone variants appeared late in evolution in eutherian mammals and are lineage-specific, being expressed in the testis (and, in the case of H2A.B, also in the brain). To date, most information about the function of these peculiar histone variants has come from studies on the H2A.B and H2A.L family in mice. In this review, we describe their unique protein characteristics, their impact on chromatin structure, and their known functions plus other possible, even non-chromatin, roles in an attempt to understand why these peculiar histone variants evolved in the first place.

Further characterization of the posttranslational modifications of core histones in response to heat and arsenite stress in Drosophila

1986 ◽  
Vol 64 (8) ◽  
pp. 750-757 ◽  
Author(s):  
Richard Desrosiers ◽  
Robert M. Tanguay
Keyword(s):  
Heat Shock ◽  
Posttranslational Modifications ◽  
Gel Electrophoresis ◽  
Cultured Cells ◽  
Histone Variants ◽  
Two Dimensional ◽  
Two Dimensional Gel Electrophoresis ◽  
Nonhistone Protein ◽  
The Core ◽  
Core Histones

The effects of a heat shock or arsenite treatment on the methylation and acetylation of core histones have been investigated in Drosophila cultured cells. The decrease in H3 methylation, which is observed during a heat shock, is not a demethylation process, but results from methylation arrest. Two-dimensional gel electrophoresis leaves no ambiguity concerning the identity of H2B as a methylated protein, since H2B and D2, a nuclear nonhistone protein, which comigrate on one-dimensional gels, are well separated on these gels. Two-dimensional gel electrophoresis in the presence of Triton X-100 resolves each of the core histones into multiple forms resulting from posttranslational modifications. There are apparently, however, no histone variants in cultured Drosophila cells. At 23 °C, the various forms of the core histones resolved on two-dimensional gels are methylated. Under heat-shock or arsenite treatment, the methylation of all forms of H3 is decreased, while that of the various forms of H2B increases. These stress conditions also induce a generalized diminution in the acetylation of all forms of core histones. In the course of a heat shock, the synthesis of H2B is increased and this newly synthesized histone remains unacetylated during the shock. These changes in the patterns of core histone methylation and acetylation may be correlated with the reorganization of gene activity brought about by the heat shock.

scholarly journals Identifying Novel Transcriptional Regulators with Circadian Expression

2015 ◽  
Vol 36 (4) ◽  
pp. 545-558 ◽  
Author(s):  
Sandra Schick ◽  
Kolja Becker ◽  
Sudhir Thakurela ◽  
David Fournier ◽  
Mareike Hildegard Hampel ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Regulatory Networks ◽  
Time Course ◽  
Noncoding Rnas ◽  
High Coverage ◽  
The Core ◽  
Circadian Expression ◽  
Clock Network ◽  
Mouse Tissues ◽  
Epigenetic Regulators

Organisms adapt their physiology and behavior to the 24-h day-night cycle to which they are exposed. On a cellular level, this is regulated by intrinsic transcriptional-translational feedback loops that are important for maintaining the circadian rhythm. These loops are organized by members of the core clock network, which further regulate transcription of downstream genes, resulting in their circadian expression. Despite progress in understanding circadian gene expression, only a few players involved in circadian transcriptional regulation, including transcription factors, epigenetic regulators, and long noncoding RNAs, are known. Aiming to discover such genes, we performed a high-coverage transcriptome analysis of a circadian time course in murine fibroblast cells. In combination with a newly developed algorithm, we identified many transcription factors, epigenetic regulators, and long intergenic noncoding RNAs that are cyclically expressed. In addition, a number of these genes also showed circadian expression in mouse tissues. Furthermore, the knockdown of one such factor, Zfp28, influenced the core clock network. Mathematical modeling was able to predict putative regulator-effector interactions between the identified circadian genes and may help for investigations into the gene regulatory networks underlying circadian rhythms.

scholarly journals Eukaryotic core histone diversification in light of the histone doublet and DNA topo II genes of Marseilleviridae

2015 ◽  
Author(s):  
Albert J Erives
Keyword(s):  
Topoisomerase Ii ◽  
Domain Architecture ◽  
Histone Variants ◽  
Core Histone ◽  
Histone Fold ◽  
The Core ◽  
Core Histones ◽  
Topo Ii ◽  
Phylogenomic Analyses ◽  
Linear Chromosomes

While eukaryotic and archaean genomes encode the histone fold domain, only eukaryotes encode the core histones H2A, H2B, H3, and H4. Core histones assemble into a hetero-octamer rather than the homo-tetramer of Archaea. Thus it was unexpected that core histone “doublets” were identified in the cytoplasmic replication factories of the Marseilleviridae (MV), one family of Nucleo-Cytoplasmic Large DNA Viruses (NCLDV). Here we analyze the core histone doublet genes from all known Marseilleviridae genomes and show that they encode obligate H2B-H2A and H4-H3 dimers of likely proto-eukaryotic origin. Each MV core histone moiety forms a sister clade to a eukaryotic core histone clade inclusive of canonical core histone paralogs, suggesting that MV core histone moieties diverged prior to eukaryotic neofunctionalizations associated with paired linear chromosomes and variant histone octamer assembly. We also show that all MV genomes encode a eukaryote-like DNA topoisomerase II enzyme that forms a clade that is sister to the eukaryotic clade. As DNA topo II influences histone deposition and chromatin compaction and is the second most abundant nuclear protein after histones, we suggest MV genes underlie a proto-chromatinized replisome that diverged prior to diversification of eukaryotic core histone variants. Thus, combined domain architecture and phylogenomic analyses suggest that a primitive origin for MV chromatin genes is a more parsimonious explanation than horizontal gene transfers + gene fusions + long-branch attraction constrained to each core histone clade. These results imply that core histones were utilized ancestrally in viral DNA compaction, protection from host endonucleases, and/or other unknown processes associated with NCLDV-like progenitors.

scholarly journals Reproductive Isolation and Morphogenetic Evolution in Drosophila Analyzed by Breakage of Ethological Barriers

Genetics ◽  
1997 ◽  
Vol 147 (1) ◽  
pp. 231-242 ◽  
Author(s):  
Lucas Sánchez ◽  
Pedro Santamaria
Keyword(s):  
Reproductive Isolation ◽  
Germ Cells ◽  
Morphological Analysis ◽  
Seminal Fluid ◽  
Germ Line ◽  
Regulatory Gene ◽  
Motile Sperm ◽  
Male And Female ◽  
Drosophila Yakuba

Abstract This article reports the breaking of ethological barriers through the constitution of soma-germ line chimeras between species of the melanogaster subgroup of Drosophila, which are ethologically isolated. Female Drosophila yakuba and D. teissieri germ cells in a D. melanogaster ovary produced functional oocytes that, when fertilized by D. melanogaster sperm, gave rise to sterile yakuba-melanogaster andteissieri-melanogaster male and female hybrids. However, the erecta-melanogaster and orena-melanogaster hybrids were lethal, since female D. erecta and D. orena germ cells in a D. melanogaster ovary failed to form oocytes with the capacity to develop normally. This failure appears to be caused by an altered interaction between the melanogaster soma and the erecta and orena germ lines. Germ cells of D. teissieri and D. orena in a D. melanogaster testis produced motile sperm that was not stored in D. melanogaster females. This might be due to incompatibility between the teissieri and orena sperm and the melanogaster seminal fluid. A morphological analysis of the terminalia of yakuba-melanogaster and teissieri-melanogaster hybrids was performed. The effect on the terminalia of teissieri-melanogaster hybrids of a mutation in doublesex, a regulatory gene that controls the development of the terminalia, was also investigated.

scholarly journals NANOS2 suppresses the cell cycle by repressing mTORC1 activators in embryonic male germ cells

iScience ◽  
2021 ◽  
pp. 102890
Author(s):  
Ryuki Shimada ◽  
Hiroko Koike ◽  
Takamasa Hirano ◽  
Yuzuru Kato ◽  
Yumiko Saga
Keyword(s):  
Cell Cycle ◽  
Germ Cells ◽  
Male Germ Cells
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