scholarly journals Parental Conflicting Role Mediates Regulation of The Chromatin Structure in The Mouse Zygote

2021 ◽  
Author(s):  
Masatoshi Ooga ◽  
Rei Inoue ◽  
Sayaka Wakayama ◽  
Satoshi Kamimura ◽  
Teruhiko Wakayama
Keyword(s):  
Germ Cells ◽  
Chromatin Structure ◽  
Fluorescence Recovery After Photobleaching ◽  
Underlying Mechanism ◽  
Formation Mechanisms ◽  
Chromatin Compaction ◽  
Relaxation Factor ◽  
Mouse Zygote ◽  
Chromatin Relaxation ◽  
Conflicting Role

Abstract Parental pronuclei (PN) are asymmetrical in several points but the underlying mechanism for this is still unclear. Recently, a theory has been become broadly accepted that sperm are more than mere vehicles to carry the paternal haploid genome into oocytes. Here, in order to reveal the formation mechanisms for parental asymmetrically relaxed chromatin structure in zygotes, we investigated histone mobility in parthenogenetic-, androgenic-, ROSI-, ELSI-, tICSI-, and ICSI-zygotes with several numbers of PNs with the use of zygotic fluorescence recovery after photobleaching, a method previous established by our group. The results showed that sperm played a role to cause chromatin compaction in both parental PNs. Interestingly, during spermiogenesis, male germ cells acquired this ability and its resistance. On the other hand, oocytes harbored chromatin relaxation ability. Furthermore, the chromatin relaxation factor was competed for between PNs. Thus, these results indicated that the parental asymmetrically relaxed chromatin structure was established as a result of a competition between the PNs for the chromatin relaxation factor that opposed the chromatin compaction effect by sperm. Together, it was suggested that parental germ cells cooperated for their just arisen newborn zygotes by playing a distinct role in the regulation of chromatin structure.

scholarly journals Thawing boar semen in the presence of seminal plasma improves motility, modifies subpopulation patterns and reduces chromatin alterations

2017 ◽  
Vol 29 (8) ◽  
pp. 1576 ◽  
Author(s):  
Rocío Fernández-Gago ◽  
Manuel Álvarez-Rodríguez ◽  
Marta E. Alonso ◽  
J. Ramiro González ◽  
Beatriz Alegre ◽  
...  
Keyword(s):  
Seminal Plasma ◽  
Chromatin Structure ◽  
Sperm Chromatin ◽  
Chromatin Compaction ◽  
Sperm Analysis ◽  
Positive Effects ◽  
Fragmentation Index ◽  
Non Linear ◽  
Boar Semen ◽  
Dna Fragmentation Index

Seminal plasma could have positive effects on boar semen after thawing. In the present study we investigated changes in the motility and chromatin structure in spermatozoa over 4 h incubation (37°C) of boar semen thawed in the presence of 0%, 10% or 50% seminal plasma from good-fertility boars. Cryopreserved doses were used from seven males, three of which were identified as susceptible to post-thawing chromatin alterations. Motility was analysed by computer-aided sperm analysis every hour, and data were used in a two-step clustering, yielding three subpopulations of spermatozoa (slow non-linear, fast non-linear, fast linear). Chromatin structure was analysed using a sperm chromatin structure assay and flow cytometry to determine the DNA fragmentation index (%DFI) as a percentage, the standard deviation of the DFI (SD-DFI) and the percentage of high DNA stainability (%HDS), indicating chromatin compaction. Thawing without seminal plasma resulted in a rapid loss of motility, whereas seminal plasma helped maintain motility throughout the incubation period and preserved the subpopulation comprising fast and linear spermatozoa. The incidence of chromatin alterations was very low in samples from non-susceptible males, whereas samples from males susceptible to post-thawing chromatin alterations exhibited marked alterations in %DFI and %HDS. Seminal plasma partly prevented these alterations in samples from susceptible males. Overall, 50% seminal plasma was the most efficient concentration to protect motility and chromatin. Some changes were concomitant with physiological events reported previously (e.g., semen thawed with 50% seminal plasma increased the production of reactive oxygen species and yielded higher fertility after AI). Thawing in the presence of seminal plasma could be particularly useful in the case of samples susceptible to post-thawing chromatin damage.

scholarly journals DNA methylation affects nuclear organization, histone modifications, and linker histone binding but not chromatin compaction

2007 ◽  
Vol 177 (3) ◽  
pp. 401-411 ◽  
Author(s):  
Nick Gilbert ◽  
Inga Thomson ◽  
Shelagh Boyle ◽  
James Allan ◽  
Bernard Ramsahoye ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Chromatin Structure ◽  
Nuclear Organization ◽  
Chromatin Condensation ◽  
Embryonic Stem ◽  
Pericentric Heterochromatin ◽  
Epigenetic Mark ◽  
Linker Histones ◽  
Chromatin Compaction ◽  
Nucleosome Structure

DNA methylation has been implicated in chromatin condensation and nuclear organization, especially at sites of constitutive heterochromatin. How this is mediated has not been clear. In this study, using mutant mouse embryonic stem cells completely lacking in DNA methylation, we show that DNA methylation affects nuclear organization and nucleosome structure but not chromatin compaction. In the absence of DNA methylation, there is increased nuclear clustering of pericentric heterochromatin and extensive changes in primary chromatin structure. Global levels of histone H3 methylation and acetylation are altered, and there is a decrease in the mobility of linker histones. However, the compaction of both bulk chromatin and heterochromatin, as assayed by nuclease digestion and sucrose gradient sedimentation, is unaltered by the loss of DNA methylation. This study shows how the complete loss of a major epigenetic mark can have an impact on unexpected levels of chromatin structure and nuclear organization and provides evidence for a novel link between DNA methylation and linker histones in the regulation of chromatin structure.

scholarly journals Role of HP1β during spermatogenesis and DNA replication

2019 ◽  
Author(s):  
Vijaya Charaka ◽  
Anjana Tiwari ◽  
Raj K Pandita ◽  
Clayton R Hunt ◽  
Tej K. Pandita
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Germ Cells ◽  
Chromatin Condensation ◽  
Genomic Stability ◽  
Replication Forks ◽  
Chromatin Protein ◽  
Male Germ Cells ◽  
Chromatin Compaction

AbstractMaintaining genomic stability in a continually dividing cell population requires accurate DNA repair, especially in male germ cells. Repair and replication protein access to DNA, however, is complicated by chromatin compaction. The HP1β chromatin protein, encoded by Cbx1, is associated with chromatin condensation but its role in meiosis is not clear. To investigate the role of Cbx1 in male germ cells, we generated testis specific Cbx1 deficient transgenic mice by crossing Cbx1flox/flox (Cbx1f/f) mice with Stra8 Cre+/− mice. Loss of Cbx1 in testes adversely affected sperm maturation and Cbx1 deletion increased seminiferous tubule degeneration and basal level DNA damage., We observed that Cbx1−/− MEF cells displayed reduced resolution of stalled DNA replication forks as well as decreased fork restart, indicating defective DNA synthesis. Taken together, these results suggest that loss of Cbx1 in growing cells leads to DNA replication defects and associated DNA damage that impact cell survival.

scholarly journals Novel nuclear role of HDAC6 in prognosis and therapeutic target for colorectal cancer

2020 ◽  
Author(s):  
Daniel J. García-Domínguez ◽  
Lourdes Hontecillas-Prieto ◽  
Maciej Kaliszczak ◽  
Miaomiao He ◽  
Miguel Angel Burguillos ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Histone Acetylation ◽  
Chromatin Structure ◽  
Therapeutic Target ◽  
Gene Array ◽  
Disease Free Survival ◽  
Wide Range ◽  
Cancer Types ◽  
Chromatin Relaxation

AbstractHistone deacetylase 6 (HDAC6) inhibition is a potential treatment of a wide range of cancer types via the acetylation of diverse proteins in the cytoplasm. However, the regulation of histone acetylation and the maintenance of higher-order chromatin structure remains unidentified. Here, we investigated the effect of selective inhibition of HDAC6 by histone acetylation, chromatin relaxation assays, co-immunoprecipitation, acetylome peptide array and in vivo RNA microarray. Our data shows that nuclear HDAC6 physically interacts with the Histone 4 lysine 12 residue, and that HDAC6 inhibition increases acetylation specifically at this residue in several cancer types. Inhibition induces major chromatin structure modulation, but has no equivalent effect on knockout HDAC6-/- MEF cells. We identified several novel HDAC6-deacetylated substrates and high expression of HDAC6 in colorectal cancer (CRC) tissue association with reduced levels of H4K12ac and independent of the key CRC driver mutations, but positively associated with EGFR expression. Furthermore, in vivo HDAC6 inhibition induces significant tumor regression in a CRC xenograft mice model with significant changes in the expression of functional nuclear genes. We also demonstrated that a DNA damaging agent in combination with selective HDAC6 inhibition is effective and acts synergistically, inducing chromatin relaxation and increased cell death in CRC cells. CRC tissues (Normal versus tumor; n=58 matched pairs) together with TCGA data analysis of 467 CRC patients showed that high HDAC6 expression is associated with metastasis, overall and disease-free survival, and is an independent risk factor of CRC stage progression. Our findings designate a new role for nuclear HDAC6 both in cancer prognosis and as a new therapeutic target for CRC and other types of cancer.HighlightHistone deacetylases 6 activity; Chromatin relaxation; Histone modifications; Gene array; DOX: doxorubicin; OXA: oxaliplatin; 5-FU: fluorouracil; Ac: acetylation; MNase: Micrococal nuclease.

scholarly journals Hatched and starved: Two chromatin compaction mechanisms join forces to silence germ cell genome

2021 ◽  
Vol 220 (9) ◽  
Author(s):  
Ana Karina Morao ◽  
Sevinc Ercan
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Nutrient Availability ◽  
Food Shortage ◽  
Chromatin Compaction ◽  
C Elegans ◽  
Cell Genome

Animals evolved in environments with variable nutrient availability and one form of adaptation is the delay of reproduction in food shortage conditions. Belew et al. (2021. J. Cell Biol.https://doi.org/10.1083/jcb.202009197) report that in the nematode C. elegans, starvation-induced transcriptional quiescence in germ cells is achieved through a pathway that combines two well-known chromatin compaction mechanisms.

scholarly journals The DNA Binding and Catalytic Domains of Poly(ADP-Ribose) Polymerase 1 Cooperate in the Regulation of Chromatin Structure and Transcription

2007 ◽  
Vol 27 (21) ◽  
pp. 7475-7485 ◽  
Author(s):  
David A. Wacker ◽  
Donald D. Ruhl ◽  
Ehsan H. Balagamwala ◽  
Kristine M. Hope ◽  
Tong Zhang ◽  
...  
Keyword(s):  
Dna Binding ◽  
Enzymatic Activity ◽  
Chromatin Structure ◽  
Transcriptional Repression ◽  
Catalytic Domain ◽  
Vitro Assay ◽  
Chromatin Compaction ◽  
Amino Terminal ◽  
Nucleosome Binding ◽  
Parp 1

ABSTRACT We explored the mechanisms of chromatin compaction and transcriptional regulation by poly(ADP-ribose) polymerase 1 (PARP-1), a nucleosome-binding protein with an NAD+-dependent enzymatic activity. By using atomic force microscopy and a complementary set of biochemical assays with reconstituted chromatin, we showed that PARP-1 promotes the localized compaction of chromatin into supranucleosomal structures in a manner independent of the amino-terminal tails of core histones. In addition, we defined the domains of PARP-1 required for nucleosome binding, chromatin compaction, and transcriptional repression. Our results indicate that the DNA binding domain (DBD) of PARP-1 is necessary and sufficient for binding to nucleosomes, yet the DBD alone is unable to promote chromatin compaction and only partially represses RNA polymerase II-dependent transcription in an in vitro assay with chromatin templates (∼50% of the repression observed with wild-type PARP-1). Furthermore, our results show that the catalytic domain of PARP-1, which does not bind nucleosomes on its own, cooperates with the DBD to promote chromatin compaction and efficient transcriptional repression in a manner independent of its enzymatic activity. Collectively, our results have revealed a novel function for the catalytic domain in chromatin compaction. In addition, they show that the DBD and catalytic domain cooperate to regulate chromatin structure and chromatin-dependent transcription, providing mechanistic insights into how these domains contribute to the chromatin-dependent functions of PARP-1.

The epigenetic tracks of aging

2014 ◽  
Vol 395 (11) ◽  
pp. 1307-1314 ◽  
Author(s):  
Carola Ingrid Weidner ◽  
Wolfgang Wagner
Keyword(s):  
Dna Methylation ◽  
Chromatin Structure ◽  
Underlying Mechanism ◽  
Histone Code ◽  
Chronological Age ◽  
Epigenetic Alterations ◽  
Biological Functions ◽  
Age Related ◽  
Random Defects ◽  
Dnam Level

Abstract Aging is associated with the deterioration of biological functions, which is either caused by accumulation of random defects or mediated by a controlled process. This article provides an overview of age-associated epigenetic alterations in the histone code, DNA-methylation (DNAm) pattern, and chromatin structure. In particular, age-related DNAm changes are highly reproducible at specific sites in the genome. The DNAm level at few CpGs facilitates estimation of chronological age and there is evidence that such predictions are indicative for biological age. Overall, aging appears to be associated with a tightly regulated epigenetic process, but the underlying mechanism remains to be elucidated.

scholarly journals Differential effects of c-Src and c-Yes on the endocytic vesicle-mediated trafficking events at the Sertoli cell blood-testis barrier: an in vitro study

2014 ◽  
Vol 307 (7) ◽  
pp. E553-E562 ◽  
Author(s):  
Xiang Xiao ◽  
Dolores D. Mruk ◽  
Elissa W. P. Wong ◽  
Will M. Lee ◽  
Daishu Han ◽  
...  
Keyword(s):  
Sertoli Cell ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Protein Trafficking ◽  
In Vitro Study ◽  
Underlying Mechanism ◽  
Endocytic Vesicle ◽  
Immunological Barrier ◽  
Blood Testis Barrier

The blood-testis barrier (BTB) is one of the tightest blood-tissue barriers in the mammalian body. However, it undergoes cyclic restructuring during the epithelial cycle of spermatogenesis in which the “old” BTB located above the preleptotene spermatocytes being transported across the immunological barrier is “disassembled,” whereas the “new” BTB found behind these germ cells is rapidly “reassembled,” i.e., mediated by endocytic vesicle-mediated protein trafficking events. Thus, the immunological barrier is maintained when preleptotene spermatocytes connected in clones via intercellular bridges are transported across the BTB. Yet the underlying mechanism(s) in particular the involving regulatory molecules that coordinate these events remains unknown. We hypothesized that c-Src and c-Yes might work in contrasting roles in endocytic vesicle-mediated trafficking, serving as molecular switches, to effectively disassemble and reassemble the old and the new BTB, respectively, to facilitate preleptotene spermatocyte transport across the BTB. Following siRNA-mediated specific knockdown of c-Src or c-Yes in Sertoli cells, we utilized biochemical assays to assess the changes in protein endocytosis, recycling, degradation and phagocytosis. c-Yes was found to promote endocytosed integral membrane BTB proteins to the pathway of transcytosis and recycling so that internalized proteins could be effectively used to assemble new BTB from the disassembling old BTB, whereas c-Src promotes endocytosed Sertoli cell BTB proteins to endosome-mediated protein degradation for the degeneration of the old BTB. By using fluorescence beads mimicking apoptotic germ cells, Sertoli cells were found to engulf beads via c-Src-mediated phagocytosis. A hypothetical model that serves as the framework for future investigation is thus proposed.

scholarly journals FANCJ couples replication past natural fork barriers with maintenance of chromatin structure

2013 ◽  
Vol 201 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Rebekka A. Schwab ◽  
Jadwiga Nieminuszczy ◽  
Kazuo Shin-ya ◽  
Wojciech Niedzwiedz
Keyword(s):  
Dna Repair ◽  
Chromatin Structure ◽  
Replication Fork ◽  
Essential Role ◽  
Chromatin Compaction ◽  
Specific Manner ◽  
In Trans ◽  
Fork Stalling ◽  
Defective Dna Repair ◽  
Lagging Strand

Defective DNA repair causes Fanconi anemia (FA), a rare childhood cancer–predisposing syndrome. At least 15 genes are known to be mutated in FA; however, their role in DNA repair remains unclear. Here, we show that the FANCJ helicase promotes DNA replication in trans by counteracting fork stalling on replication barriers, such as G4 quadruplex structures. Accordingly, stabilization of G4 quadruplexes in ΔFANCJ cells restricts fork movements, uncouples leading- and lagging-strand synthesis and generates small single-stranded DNA gaps behind the fork. Unexpectedly, we also discovered that FANCJ suppresses heterochromatin spreading by coupling fork movement through replication barriers with maintenance of chromatin structure. We propose that FANCJ plays an essential role in counteracting chromatin compaction associated with unscheduled replication fork stalling and restart, and suppresses tumorigenesis, at least partially, in this replication-specific manner.

scholarly journals The Dynamic Influence of Linker Histone Saturation within the Poly-Nucleosome Array

2020 ◽  
Author(s):  
Dustin C. Woods ◽  
Francisco Rodríguez-Ropero ◽  
Jeff Wereszczynski
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Long Range ◽  
Chromatin Structure ◽  
Linker Histone ◽  
Linker Histones ◽  
Chromatin Compaction ◽  
Chromatin Fibers ◽  
Dynamics Simulations ◽  
Nucleosome Arrays

AbstractLinker histones bind to nucleosomes and modify chromatin structure and dynamics as a means of epigenetic regulation. Biophysical studies have shown that chromatin fibers can adopt a plethora of conformations with varying levels of compaction. Linker histone condensation, and its specific binding disposition, has been associated with directly tuning this ensemble of states. However, the atomistic dynamics and quantification of this mechanism remains poorly understood. Here, we present molecular dynamics simulations of octa-nucleosome arrays, based on a cryo-EM structure of the 30-nm chromatin fiber, with and without the globular domains of the H1 linker histone to determine how they influence fiber structures and dynamics. Results show that when bound, linker histones inhibit DNA flexibility and stabilize repeating tetra-nucleosomal units, giving rise to increased chromatin compaction. Furthermore, upon the removal of H1, there is a significant destabilization of this compact structure as the fiber adopts less strained and untwisted states. Interestingly, linker DNA sampling in the octa-nucleosome is exaggerated compared to its mono-nucleosome counterparts, suggesting that chromatin architecture plays a significant role in DNA strain even in the absence of linker histones. Moreover, H1-bound states are shown to have increased stiffness within tetra-nucleosomes, but not between them. This increased stiffness leads to stronger long-range correlations within the fiber, which may result in the propagation of epigenetic signals over longer spatial ranges. These simulations highlight the effects of linker histone binding on the internal dynamics and global structure of poly-nucleosome arrays, while providing physical insight into a mechanism of chromatin compaction.SignificanceLinker histones dynamically bind to DNA in chromatin fibers and serve as epigentic regulators. However, the extent to which they influence the gamut of chromatin architecture is still not well understood. Using molecular dynamics simulations, we studied compact octa-nucleosome arrays with and without the H1 linker histone to better understand the mechanisms dictating the structure of the chromatin fiber. Inclusion of H1 results in stabilization of the compact chromatin structure, while its removal results in a major conformational change towards an untwisted ladder-like state. The increased rigidity and correlations within the H1-bound array suggests that H1-saturated chromatin fibers are better suited to transferring long-range epigentic information.

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