scholarly journals Biparental contributions of the H2A.B histone variant control embryonic development in mice

PLoS Biology ◽  
2020 ◽  
Vol 18 (12) ◽  
pp. e3001001
Author(s):  
Antoine Molaro ◽  
Anna J. Wood ◽  
Derek Janssens ◽  
Selina M. Kindelay ◽  
Michael T. Eickbush ◽  
...  

Histone variants expand chromatin functions in eukaryote genomes. H2A.B genes are testis-expressed short histone H2A variants that arose in placental mammals. Their biological functions remain largely unknown. To investigate their function, we generated a knockout (KO) model that disrupts all 3 H2A.B genes in mice. We show that H2A.B KO males have globally altered chromatin structure in postmeiotic germ cells. Yet, they do not show impaired spermatogenesis or testis function. Instead, we find that H2A.B plays a crucial role postfertilization. Crosses between H2A.B KO males and females yield embryos with lower viability and reduced size. Using a series of genetic crosses that separate parental and zygotic contributions, we show that the H2A.B status of both the father and mother, but not of the zygote, affects embryonic viability and growth during gestation. We conclude that H2A.B is a novel parental-effect gene, establishing a role for short H2A histone variants in mammalian development. We posit that parental antagonism over embryonic growth drove the origin and ongoing diversification of short histone H2A variants in placental mammals.


Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 867 ◽  
Author(s):  
Xuanzhao Jiang ◽  
Tatiana A. Soboleva ◽  
David J. Tremethick

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.



2009 ◽  
Vol 87 (1) ◽  
pp. 35-50 ◽  
Author(s):  
Mohammed Altaf ◽  
Andréanne Auger ◽  
Marcela Covic ◽  
Jacques Côté

The organization of the eukaryotic genome into chromatin makes it inaccessible to the factors required for gene transcription and DNA replication, recombination, and repair. In addition to histone-modifying enzymes and ATP-dependent chromatin remodeling complexes, which play key roles in regulating many nuclear processes by altering the chromatin structure, cells have developed a mechanism of modulating chromatin structure by incorporating histone variants. These variants are incorporated into specific regions of the genome throughout the cell cycle. H2A.Z, which is an evolutionarily conserved H2A variant, performs several seemingly unrelated and even contrary functions. Another H2A variant, H2A.X, plays a very important role in the cellular response to DNA damage. This review summarizes the recent developments in our understanding of the role of H2A.Z and H2A.X in the regulation of chromatin structure and function, focusing on their functional links with chromatin modifying and remodeling complexes.



2006 ◽  
Vol 27 (3) ◽  
pp. 1146-1157 ◽  
Author(s):  
Chantal Kress ◽  
Carole Gautier-Courteille ◽  
H. Beverley Osborne ◽  
Charles Babinet ◽  
Luc Paillard

ABSTRACT CUG-BP1/CELF1 is a multifunctional RNA-binding protein involved in the regulation of alternative splicing and translation. To elucidate its role in mammalian development, we produced mice in which the Cugbp1 gene was inactivated by homologous recombination. These Cugbp1 − / − mice were viable, although a significant portion of them did not survive after the first few days of life. They displayed growth retardation, and most Cugbp1 − / − males and females exhibited impaired fertility. Male infertility was more thoroughly investigated. Histological examination of testes from Cugbp1 − / − males showed an arrest of spermatogenesis that occurred at step 7 of spermiogenesis, before spermatid elongation begins, and an increased apoptosis. A quantitative reverse transcriptase PCR analysis showed a decrease of all the germ cell markers tested but not of Sertoli and Leydig markers, suggesting a general decrease in germ cell number. In wild-type testes, CUG-BP1 is expressed in germ cells from spermatogonia to round spermatids and also in Sertoli and Leydig cells. These findings demonstrate that CUG-BP1 is required for completion of spermatogenesis.



2005 ◽  
Vol 25 (23) ◽  
pp. 10639-10651 ◽  
Author(s):  
Mitsuru Okuwaki ◽  
Kohsuke Kato ◽  
Hideto Shimahara ◽  
Shin-ichi Tate ◽  
Kyosuke Nagata

ABSTRACT Histone variants play important roles in the maintenance and regulation of the chromatin structure. In order to characterize the biochemical properties of the chromatin structure containing histone variants, we investigated the dynamic status of nucleosome core particles (NCPs) that were assembled with recombinant histones. We found that in the presence of nucleosome assembly protein I (NAP-I), a histone chaperone, H2A-Barr body deficient (H2A.Bbd) confers the most flexible nucleosome structure among the mammalian histone H2A variants known thus far. NAP-I mediated the efficient assembly and disassembly of the H2A.Bbd-H2B dimers from NCPs. This reaction was accomplished more efficiently when the NCPs contained H3.3, a histone H3 variant known to be localized in the active chromatin, than when the NCPs contained the canonical H3. These observations indicate that the histone variants H2A.Bbd and H3.3 are involved in the formation and maintenance of the active chromatin structure. We also observed that acidic histone binding proteins, TAF-I/SET and B23.1, demonstrated dimer assembly and disassembly activity, but the efficiency of their activity was considerably lower than that of NAP-I. Thus, both the acidic nature of NAP-I and its other functional structure(s) may be essential to mediate the assembly and disassembly of the dimers in NCPs.



2005 ◽  
Vol 83 (4) ◽  
pp. 505-515 ◽  
Author(s):  
Andra Li ◽  
José M Eirín-López ◽  
Juan Ausió

During the last decade, chromatin research has been focusing on the role of histone variability as a modulator of chromatin structure and function. Histone variability can be the result of either post-translational modifications or intrinsic variation at the primary structure level: histone variants. In this review, we center our attention on one of the most extensively characterized of such histone variants in recent years, histone H2AX. The molecular phylogeny of this variant seems to have run in parallel with that of the major canonical somatic H2A1 in eukaryotes. Functionally, H2AX appears to be mainly associated with maintaining the genome integrity by participating in the repair of the double-stranded DNA breaks exogenously introduced by environmental damage (ionizing radiation, chemicals) or in the process of homologous recombination during meiosis. At the structural level, these processes involve the phosphorylation of serine at the SQE motif, which is present at the very end of the C-terminal domain of H2AX, and possibly other PTMs, some of which have recently started to be defined. We discuss a model to account for how these H2AX PTMs in conjunction with chromatin remodeling complexes (such as INO80 and SWRI) can modify chromatin structure (remodeling) to support the DNA unraveling ultimately required for DNA repair.Key words: H2AX, DNA repair, double-stranded DNA breaks, phosphorylation.



2020 ◽  
Vol 477 (17) ◽  
pp. 3367-3386
Author(s):  
Yan Huang ◽  
Yaxin Dai ◽  
Zheng Zhou

Histone chaperones include a wide variety of proteins which associate with histones and regulate chromatin structure. The classic H2A–H2B type of histone chaperones, and the chromatin remodeling complex components possessing H2A–H2B chaperone activity, show a broad range of structures and functions. Rapid progress in the structural and functional study of H2A–H2B chaperones extends our knowledge about the epigenetic regulation of chromatin. In this review, we summarize the most recent advances in the understanding of the structure and function of H2A–H2B chaperones that interact with either canonical or variant H2A–H2B dimers. We discuss the current knowledge of the H2A–H2B chaperones, which present no preference for canonical and variant H2A–H2B dimers, describing how they interact with H2A–H2B to fulfill their functions. We also review recent advances of H2A variant-specific chaperones, demarcating how they achieve specific recognition for histone variant H2A.Z and how these interactions regulate chromatin structure by nucleosome editing. We highlight the universal mechanism underlying H2A–H2B dimers recognition by a large variety of histone chaperones. These findings will shed insight into the biological impacts of histone chaperone, chromatin remodeling complex, and histone variants in chromatin regulation.



Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 659
Author(s):  
Sebastiano Giallongo ◽  
Oriana Lo Re ◽  
Gabriela Lochmanová ◽  
Luca Parca ◽  
Francesco Petrizzelli ◽  
...  

Background: Gene expression in eukaryotic cells can be governed by histone variants, which replace replication-coupled histones, conferring unique chromatin properties. MacroH2A1 is a histone H2A variant containing a domain highly similar to H2A and a large non-histone (macro) domain. MacroH2A1, in turn, is present in two alternatively exon-spliced isoforms: macroH2A1.1 and macroH2A1.2, which regulate cell plasticity and proliferation in a remarkably distinct manner. The N-terminal and the C-terminal tails of H2A histones stem from the nucleosome core structure and can be target sites for several post-translational modifications (PTMs). MacroH2A1.1 and macroH2A1.2 isoforms differ only in a few amino acids and their ability to bind NAD-derived metabolites, a property allegedly conferring their different functions in vivo. Some of the modifications on the macroH2A1 variant have been identified, such as phosphorylation (T129, S138) and methylation (K18, K123, K239). However, no study to our knowledge has analyzed extensively, and in parallel, the PTM pattern of macroH2A1.1 and macroH2A1.2 in the same experimental setting, which could facilitate the understanding of their distinct biological functions in health and disease. Methods: We used a mass spectrometry-based approach to identify the sites for phosphorylation, acetylation, and methylation in green fluorescent protein (GFP)-tagged macroH2A1.1 and macroH2A1.2 expressed in human hepatoma cells. The impact of selected PTMs on macroH2A1.1 and macroH2A1.2 structure and function are demonstrated using computational analyses. Results: We identified K7 as a new acetylation site in both macroH2A1 isoforms. Quantitative comparison of histone marks between the two isoforms revealed significant differences in the levels of phosphorylated T129 and S170. Our computational analysis provided evidence that the phosphorylation status in the intrinsically disordered linker region in macroH2A1 isoforms might represent a key regulatory element contributing to their distinct biological responses. Conclusions: Taken together, our results report different PTMs on the two macroH2A1 splicing isoforms as responsible for their distinct features and distribution in the cell.



1996 ◽  
Vol 16 (8) ◽  
pp. 4305-4311 ◽  
Author(s):  
X Liu ◽  
B Li ◽  
GorovskyMA

Although variants have been identified for every class of histone, their functions remain unknown. We have been studying the histone H2A variant hv1 in the ciliated protozoan Tetrahymena thermophila. Sequence analysis indicates that hv1 belongs to the H2A.F/Z type of histone variants. On the basis of the high degree of evolutionary conservation of this class of histones, they are proposed to have one or more distinct and essential functions that cannot be performed by their major H2A counterparts. Considerable evidence supports the hypothesis that the hv1 protein in T. thermophila and hv1-like proteins in other eukaryotes are associated with active chromatin. In T. thermophila, simple mass transformation and gene replacement techniques have recently become available. In this report, we demonstrate that either the HTA1 gene or the HTA2 gene, encoding the major H2As, can be completely replaced by disrupted genes in the polyploid, transcriptionally active macronucleus, indicating that neither of the two genes is essential. However, only some of the HTA3 genes encoding hv1 can be replaced by disrupted genes, indicating that the H2A.F/Z type variants have an essential function that cannot be performed by the major H2A genes. Thus, an essential gene in T. thermophila can be defined by the fact that it can be partially, but not completely, eliminated from the polyploid macronucleus. To our knowledge, this study represents the first use of gene disruption technology to study core histone gene function in any organism other than yeast and the first demonstration of an essential gene in T. thermophila using these methods. When a rescuing plasmid carrying a wild-type HTA3 gene was introduced into the T. thermophila cells, the endogenous chromosomal HTA3 could be completely replaced, defining a gene replacement strategy that can be used to analyze the function of essential genes.



1984 ◽  
Vol 44 (2) ◽  
pp. 219-224 ◽  
Author(s):  
Ursula Mittwoch ◽  
Shantha Mahadevaiah ◽  
Leslie A. Setterfield

SUMMARYTwo male-sterile chromosome anomalies, the insertion Is(7; 1)40H and the tertiary trisomy, Ts(512)31H, were found to be associated with reduced ovarian volumes in immature females. Together with the reciprocal translocation, T(11; 19)42H, in which this effect was described previously, reduced ovaries have been found in all three male-sterile chromosome anomalies investigated so far, suggesting that ovarian involvement is likely to be common in these conditions. Assuming that the smaller ovarian size reflects a reduction in the number of oocytes, it is suggested that male-sterile chromosome anomalies may exert basically similar deleterious effects on meiotic germ cells in males and females, the difference in outcome being due to cell-physiological differences between spermatocytes and oocytes and to the small number of surviving oocytes required for fertility in females.



2003 ◽  
Vol 81 (3) ◽  
pp. 131-140 ◽  
Author(s):  
John D Lewis ◽  
D Wade Abbott ◽  
Juan Ausió

The process of meiosis reduces a diploid cell to four haploid gametes and is accompanied by extensive recombination. Thus, the dynamics of chromatin during meiosis are significantly different than in mitotic cells. As spermatogenesis progresses, there is a widespread reorganization of the haploid genome followed by extensive DNA compaction. It has become increasingly clear that the dynamic composition of chromatin plays a critical role in the activities of enzymes and processes that act upon it. Therefore, an analysis of the role of histone variants and modifications in these processes may shed light upon the mechanisms involved and the control of chromatin structure in general. Histone variants such as histone H3.3, H2AX, and macroH2A appear to play key roles in the various stages of spermiogenesis, in addition to the specifically modulated acetylation of histone H4 (acH4), ubiquitination of histones H2A and H2B (uH2A, uH2B), and phosphorylation of histone H3 (H3p). This review will examine recent discoveries concerning the role of histone modifications and variants during meiosis and spermatogenesis.Key words: histone variants, histone modifications, chromatin structure, meiosis.



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