scholarly journals Large-scale DNA demethylation occurs in proliferating ovarian granulosa cells during mouse follicular development

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Tomoko Kawai ◽  
JoAnne S. Richards ◽  
Masayuki Shimada
Keyword(s):  
Dna Methylation ◽  
Granulosa Cell ◽  
Granulosa Cells ◽  
Dna Methyltransferase ◽  
Large Scale ◽  
Follicular Development ◽  
Dna Structure ◽  
Dna Demethylation ◽  
Promoter Regions ◽  
Equine Chorionic Gonadotropin

AbstractDuring ovarian follicular development, granulosa cells proliferate and progressively differentiate to support oocyte maturation and ovulation. To determine the underlying links between proliferation and differentiation in granulosa cells, we determined changes in 1) the expression of genes regulating DNA methylation and 2) DNA methylation patterns, histone acetylation levels and genomic DNA structure. In response to equine chorionic gonadotropin (eCG), granulosa cell proliferation increased, DNA methyltransferase (DNMT1) significantly decreased and Tet methylcytosine dioxygenase 2 (TET2) significantly increased in S-phase granulosa cells. Comprehensive MeDIP-seq analyses documented that eCG treatment decreased methylation of promoter regions in approximately 40% of the genes in granulosa cells. The expression of specific demethylated genes was significantly increased in association with specific histone modifications and changes in DNA structure. These epigenetic processes were suppressed by a cell cycle inhibitor. Based on these results, we propose that the timing of sequential epigenetic events is essential for progressive, stepwise changes in granulosa cell differentiation.

scholarly journals AKT is involved in granulosa cell autophagy regulation via mTOR signaling during rat follicular development and atresia

Reproduction ◽  
2014 ◽  
Vol 147 (1) ◽  
pp. 73-80 ◽  
Author(s):  
JongYeob Choi ◽  
MinWha Jo ◽  
EunYoung Lee ◽  
DooSeok Choi
Keyword(s):  
Cell Death ◽  
Granulosa Cell ◽  
Granulosa Cells ◽  
Apoptotic Cell ◽  
Follicular Development ◽  
Negative Regulator ◽  
Metabolic Clearance ◽  
Akt Inhibitor ◽  
Western Blots

In this study, we examined whether granulosa cell autophagy during follicular development and atresia was regulated by the class I phosphoinositide-3 kinase/protein kinase B (AKT) pathway, which is known to control the activity of mammalian target of rapamycin (mTOR), a major negative regulator of autophagy. Ovaries and granulosa cells were obtained using an established gonadotropin-primed immature rat model that induces follicular development and atresia. Autophagy was evaluated by measuring the expression level of microtubule-associated protein light chain 3-II (LC3-II) using western blots and immunohistochemistry. The activity of AKT and mTOR was also examined by observing the phosphorylation of AKT and ribosomal protein S6 kinase (S6K) respectively. After gonadotropin injection, LC3-II expression was suppressed and phosphorylation of AKT and S6K increased in rat granulosa cells. By contrast, gonadotropin withdrawal by metabolic clearance promoted LC3-II expression and decreased phosphorylation of AKT and S6K. In addition,in-vitroFSH treatment of rat granulosa cells also indicated inhibition of LC3-II expression accompanied by a marked increase in phosphorylation of AKT and S6K. Inhibition of AKT phosphorylation using AKT inhibitor VIII suppressed FSH-mediated phosphorylation of S6K, followed by an increase in LC3-II expression. Furthermore, co-treatment with FSH and AKT inhibitor increased the levels of apoptosis and cell death of granulosa cells compared with the single treatment with FSH. Taken together, our findings indicated that AKT-mediated activation of mTOR suppresses granulosa cell autophagy during follicular development and is involved in the regulation of apoptotic cell death.

scholarly journals Fetal and Neonatal Exposure to the Endocrine Disruptor Methoxychlor Causes Epigenetic Alterations in Adult Ovarian Genes

Endocrinology ◽  
2009 ◽  
Vol 150 (10) ◽  
pp. 4681-4691 ◽  
Author(s):  
Aparna Mahakali Zama ◽  
Mehmet Uzumcu
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
Ovarian Function ◽  
Endocrine Disrupting Chemicals ◽  
Neonatal Exposure ◽  
Dna Hypermethylation ◽  
Promoter Regions ◽  
Altered Expression ◽  
Arbitrarily Primed Pcr ◽  
Methylation Patterns

Abstract Exposure to endocrine-disrupting chemicals during development could alter the epigenetic programming of the genome and result in adult-onset disease. Methoxychlor (MXC) and its metabolites possess estrogenic, antiestrogenic, and antiandrogenic activities. Previous studies showed that fetal/neonatal exposure to MXC caused adult ovarian dysfunction due to altered expression of key ovarian genes including estrogen receptor (ER)-β, which was down-regulated, whereas ERα was unaffected. The objective of the current study was to evaluate changes in global and gene-specific methylation patterns in adult ovaries associated with the observed defects. Rats were exposed to MXC (20 μg/kg·d or 100 mg/kg·d) between embryonic d 19 and postnatal d 7. We performed DNA methylation analysis of the known promoters of ERα and ERβ genes in postnatal d 50–60 ovaries using bisulfite sequencing and methylation-specific PCRs. Developmental exposure to MXC led to significant hypermethylation in the ERβ promoter regions (P < 0.05), whereas the ERα promoter was unaffected. We assessed global DNA methylation changes using methylation-sensitive arbitrarily primed PCR and identified 10 genes that were hypermethylated in ovaries from exposed rats. To determine whether the MXC-induced methylation changes were associated with increased DNA methyltransferase (DNMT) levels, we measured the expression levels of Dnmt3a, Dnmt3b, and Dnmt3l using semiquantitative RT-PCR. Whereas Dnmt3a and Dnmt3l were unchanged, Dnmt3b expression was stimulated in ovaries of the 100 mg/kg MXC group (P < 0.05), suggesting that increased DNMT3B may cause DNA hypermethylation in the ovary. Overall, these data suggest that transient exposure to MXC during fetal and neonatal development affects adult ovarian function via altered methylation patterns.

scholarly journals Identification of transcription termination defects at DNA hypomethylated transcription termination sites in DNA methyltransferase 3a-deficient vertebrates.

2021 ◽  
Author(s):  
Masaki Shirai ◽  
Takuya Nara ◽  
Haruko Takahashi ◽  
Kazuya Takayama ◽  
Yuan Chen ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
De Novo ◽  
Es Cells ◽  
Transcription Termination ◽  
Promoter Regions ◽  
Zebrafish Model ◽  
Body Regions ◽  
Chimeric Transcripts ◽  
Dna Methyltransferase 3A

CpG methylation in genomic DNA is well known as a repressive epigenetic marker in eukaryotic transcription, and DNA methylation of the promoter regions is correlated with silencing of gene expression. In contrast to the promoter regions, the function of DNA methylation during transcription termination remains to be elucidated. A recent study has revealed that mouse DNA methyltransferase 3a (Dnmt3a) mainly functions in de novo methylation in the promoter and gene body regions (including transcription termination sites (TTSs)) during development. To investigate the relationship between DNA methylation overlapping the TTSs and transcription termination, we employed two strategies: informatic analysis using already deposited datasets of Dnmt3a-/- mouse cells and the zebrafish model system. Bioinformatic analysis using methylome and transcriptome data showed that hypomethylated differentially methylated regions overlapping the TTSs were associated with increased read counts and chimeric transcripts downstream of TTSs in Dnmt3a-/- Agouti-related protein neurons, but not in Dnmt3a-/- ES cells and MEFs. We experimentally detected increased read-through and chimeric transcripts downstream of hypomethylated TTSs in zebrafish maternal-zygotic dnmt3aa-/- mutants. This study is the first to identify transcription termination defects in DNA hypomethylated TTSs in Dnmt3a-/- vertebrates.

scholarly journals Unraveling the functional role of DNA methylation using targeted DNA demethylation by steric blockage of DNA methyltransferase with CRISPR/dCas9

2020 ◽  
Author(s):  
Daniel M. Sapozhnikov ◽  
Moshe Szyf
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Promoter Region ◽  
Dna Methyltransferase ◽  
Dna Demethylation ◽  
New Method ◽  
Inducible Promoters ◽  
Specific Targeting ◽  
Main Effect

AbstractAlthough associations between DNA methylation and gene expression were established four decades ago, the causal role of DNA methylation in gene expression remains unresolved. Different strategies to address this question were developed; however, all are confounded and fail to disentangle cause and effect. We developed here a highly effective new method using only deltaCas9(dCas9):gRNA site-specific targeting to physically block DNA methylation at specific targets in the absence of a confounding flexibly-tethered enzymatic activity, enabling examination of the role of DNA methylation per se in living cells. We show that the extensive induction of gene expression achieved by TET/dCas9-based targeting vectors is confounded by DNA methylation-independent activities, inflating the role of DNA methylation in the promoter region. Using our new method, we show that in several inducible promoters, the main effect of DNA methylation is silencing basal promoter activity. Thus, the effect of demethylation of the promoter region in these genes is small, while induction of gene expression by different inducers is large and DNA methylation independent. In contrast, targeting demethylation to the pathologically silenced FMR1 gene targets robust induction of gene expression. We also found that standard CRISPR/Cas9 knockout generates a broad unmethylated region around the deletion, which might confound interpretation of CRISPR/Cas9 gene depletion studies. In summary, this new method could be used to reveal the true extent, nature, and diverse contribution to gene regulation of DNA methylation at different regions.

Effects of ten–eleven translocation 1 (Tet1) on DNA methylation and gene expression in chicken primordial germ cells

2019 ◽  
Vol 31 (3) ◽  
pp. 509 ◽  
Author(s):  
Minli Yu ◽  
Dongfeng Li ◽  
Wanyan Cao ◽  
Xiaolu Chen ◽  
Wenxing Du
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Germ Cells ◽  
Dna Methyltransferase ◽  
Primordial Germ Cells ◽  
Dna Demethylation ◽  
Caveolin 1 ◽  
Expression Of Genes ◽  
Deleted In Azoospermia

Ten–eleven translocation 1 (Tet1) is involved in DNA demethylation in primordial germ cells (PGCs); however, the precise regulatory mechanism remains unclear. In the present study the dynamics of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) in developing PGCs and the role of Tet1 in PGC demethylation were analysed. Results show that 5mC levels dropped significantly after embryonic Day 4 (E4) and 5hmC levels increased reaching a peak at E5–E5.5. Interestingly, TET1 protein was highly expressed during E5 to E5.5, which showed a consistent trend with 5hmC. The expression of pluripotency-associated genes (Nanog, PouV and SRY-box 2 (Sox2)) and germ cell-specific genes (caveolin 1 (Cav1), piwi-like RNA-mediated gene silencing 1 (Piwi1) and deleted in azoospermia-like (Dazl)) was upregulated after E5, whereas the expression of genes from the DNA methyltransferase family was decreased. Moreover, the Dazl gene was highly methylated in early PGCs and then gradually hypomethylated. Knockdown of Tet1 showed impaired survival and proliferation of PGCs, as well as increased 5mC levels and reduced 5hmC levels. Further analysis showed that knockdown of Tet1 led to elevated DNA methylation levels of Dazl and downregulated gene expression including Dazl. Thus, this study reveals the dynamic epigenetic reprogramming of chicken PGCs invivo and the molecular mechanism of Tet1 in regulating genomic DNA demethylation and hypomethylation of Dazl during PGC development.

scholarly journals Continuous Zebularine Treatment Effectively Sustains Demethylation in Human Bladder Cancer Cells

2004 ◽  
Vol 24 (3) ◽  
pp. 1270-1278 ◽  
Author(s):  
Jonathan C. Cheng ◽  
Daniel J. Weisenberger ◽  
Felicidad A. Gonzales ◽  
Gangning Liang ◽  
Guo-Liang Xu ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
Promoter Regions ◽  
Bladder Cancer Cells ◽  
Continuous Application ◽  
Aberrant Dna Methylation ◽  
Human Bladder Cancer Cells ◽  
Partial Depletion

ABSTRACT During tumorigenesis, tumor suppressor and cancer-related genes are commonly silenced by aberrant DNA methylation in their promoter regions. Recently, we reported that zebularine [1-(β-d-ribofuranosyl)-1,2-dihydropyrimidin-2-one] acts as an inhibitor of DNA methylation and exhibits chemical stability and minimal cytotoxicity both in vitro and in vivo. Here we show that continuous application of zebularine to T24 cells induces and maintains p16 gene expression and sustains demethylation of the 5′ region for over 40 days, preventing remethylation. In addition, continuous zebularine treatment effectively and globally demethylated various hypermethylated regions, especially CpG-poor regions. The drug caused a complete depletion of extractable DNA methyltransferase 1 (DNMT1) and partial depletion of DNMT3a and DNMT3b3. Last, sequential treatment with 5-aza-2′-deoxycytidine followed by zebularine hindered the remethylation of the p16 5′ region and gene resilencing, suggesting the possible combination use of both drugs as a potential anticancer regimen.

Title: Promoter Methylation of Selected Genes and Response to Azacitidine (AZ) Therapy in Patients with Non-BCR-ABL Myeloproliferative Disorders (MPDs)

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4625-4625
Author(s):  
Nicholas Achille ◽  
Laura Michaelis ◽  
Scott E. Smith ◽  
Eliza Germano ◽  
Nancy J. Zeleznik-Le ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Promoter Methylation ◽  
Research Funding ◽  
Dna Methyltransferase ◽  
Methylation Status ◽  
Cpg Islands ◽  
Myeloproliferative Disorders ◽  
Response To Treatment ◽  
Promoter Regions ◽  
Days Of Therapy

Abstract Abstract 4625 Background: Gene silencing via methylation of CpG islands in the promoter regions of many genes but specifically of APAF1, p15INK4B, p16INK4A, RARB, and CDH1 appears to play a role in pathogenesis of myeloid malignancies. Azacitidine (AZ) causes demethylation by inhibiting DNA methyltransferase and has already been shown to be an effective therapy for myelodysplastic syndromes. The demethylation induced by AZ is detectable in about 48 hours and increases significantly after 5 days of therapy. After that, the effect tends to plateau. Methods: We initiated a Phase 2 study of patients with non-BCR-ABL MPDs to determine clinical response to AZ therapy and correlate it with promoter DNA methylation and gene re-expression. The protocol was approved by the institutional IRB. Patients received AZ 75mg/m2 s/c for days 1–7 and repeated every 28 days for a minimum of 4 cycles. Responders were allowed to continue treatment until disease progression. Pretreatment and D 7 peripheral blood samples were analyzed for promoter methylation status and expression of the 5 genes mentioned above. Bisulfite conversion of DNA was followed by quantitative PCR using primers specific for methylated or for unmethylated promoter regions. For gene re-expression analysis, quantitative RT-PCR was performed with RNA isolated from the same patient samples and the same time points as the DNA methylation analyses. Results: Seven patients were enrolled before the study closed due to lack of accrual. The diagnoses were: Myelofibrosis (MF) 4, essential thrombocythemia 1, unclassified MPD with dysplasia 2. One patient with MF and one with unclassified MPD responded, the latter with normalization of marrow karyotype. Both responses were accompanied by significant decrease in APAF1 promoter methylation and surprisingly, an increase in promoter methylation of RARB. In three of the non-responders, APAF1 methylation increased. In patients with decreased Apaf1 methylation, a statistically significant increase in mRNA expression was observed. Conclusions: Within its limitations, this small trial shows that the methylation status of selected genes, particularly of APAF1 and RARB (inversely) is associated with response to treatment with azacitidine in patients with MPDs. In non-responders, Apaf1 methylation appears to increase. A larger study will be necessary to confirm these preliminary observations. Disclosures: Smith: Seattle Genetics, Inc.: Research Funding; Cephalon: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Spectrum: Consultancy; GSK: Speakers Bureau. Nand:Celgene Corporation: Research Funding.

Genetic or Pharmacological Reductions in DNA Methylation Selectively Inhibit Peripheral T-Cell Lymphomagenesis.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2760-2760
Author(s):  
Jennifer J. Trowbridge ◽  
Mingjie Li ◽  
Charles W.M. Roberts ◽  
Stuart H. Orkin
Keyword(s):  
Dna Methylation ◽  
T Cells ◽  
T Cell ◽  
Myeloid Leukemia ◽  
Dna Methyltransferase ◽  
Cell Lymphoma ◽  
Dna Demethylation ◽  
T Cell Lymphoma ◽  
Demethylating Agents ◽  
Dna Methylation Inhibitors

Abstract Abstract 2760 The significance of mutations in components of the DNA methylation machinery in blood cancer has become a topic of intense investigation. Unlike genetic modifications, the reversible nature of DNA methylation and other epigenetic changes makes them attractive therapeutic targets. Very recently, mutations in the DNA methyltransferase DNMT3A and the DNA demethylase TET2 were identified in human peripheral T cell lymphoma (PTCL) [1]. These findings provided a novel link between the development and progression of PTCL with deregulation of DNA methylation processes. Importantly, this finding also extended the few known mutations associated with both T-cell lymphoma and myeloid leukemia. Our previous work identified acute sensitivity of MLL-AF9–induced myeloid leukemia (AML) to DNA demethylation through loss or haploinsufficiency of the DNA methyltransferase Dnmt1 [2]. Here, we investigated the sensitivity of PTCL to DNA demethylation. Lymphoma was induced in mice by inactivation of Snf5, a core subunit of the SWI/SNF chromatin remodeling complex, driven by CD4Cre (CD4Cre-Snf52lox). Inactivation of Snf5 leads to rapid onset of mature CD8+ PTCL with a median survival of 10 weeks of age. Strikingly, loss of Dnmt1 in this model (CD4Cre-Snf52lox-Dnmt12lox) completely abrogated development of lymphoma. Furthermore, haploinsufficiency of Dnmt1 was sufficient to increase event-free survival to 13 weeks of age (p=0.0008). Loss or haploinsufficiency of Dnmt1 did not impact normal T cell development in the thymus with the exception of a modest reduction in CD8+ CD44hi memory T cells. Based on the selective response of PTCL to reduced levels of Dnmt1 and DNA methylation, we screened a panel of pharmacological DNA demethylating agents for efficacy in PTCL. We found three putative DNA methylation inhibitors; the nucleoside inhibitor zebularine and non-nucleoside inhibitors RG108 and procainamide, which inhibited proliferation of primary murine PTCL in vitro. These inhibitors were effective at doses that did not restrict the proliferation of normal CD8+ T cells. When these inhibitors were evaluated for efficacy in vivo, both zebularine and procainamide were found to inhibit growth of primary murine PTCL. Together, these results suggest that therapy of PTCL with DNA methylation inhibitors or other DNA demethylating agents may achieve a favorable therapeutic index. Further, these results support the concept of a shared competitive advantage of myeloid leukemia and T-cell lymphoma in carrying mutations in the DNA methylation machinery. [1] Couronne L et al., NEJM, 2012, 366:95-6; [2] Trowbridge et al., Genes Dev, 2012, 26:344-9. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The Phytoestrogen Quercetin Impairs Steroidogenesis and Angiogenesis in Swine Granulosa Cells In Vitro

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Sujen Eleonora Santini ◽  
Giuseppina Basini ◽  
Simona Bussolati ◽  
Francesca Grasselli
Keyword(s):  
Granulosa Cell ◽  
Granulosa Cells ◽  
Follicular Development ◽  
Redox Status ◽  
Negative Influence ◽  
Animal Nutrition ◽  
Follicle Development ◽  
Vascular Endothelial ◽  
Endothelial Growth Factor

Experimental evidence documents that nutritional phytoestrogens may interact with reproductive functions but the exact mechanism of action is still controversial. Since quercetin is one of the main flavonoids in livestock nutrition, we evaluated its possible effects on cultured swine granulosa cell proliferation, steroidogenesis, and redox status. Moreover, since angiogenesis is essential for follicle development, the effect of the flavonoid on Vascular Endothelial Growth Factor output by granulosa cells was also taken into account. Our data evidence that quercetin does not affect granulosa cell growth while it inhibits progesterone production and modifies estradiol production in a dose-related manner. Additionally, the flavonoid interferes with the angiogenic process by inhibiting VEGF production as well as by altering redox status. Since steroidogenesis and angiogenesis are strictly involved in follicular development, these findings appear particularly relevant, pointing out a possible negative influence of quercetin on ovarian physiology. Therefore, the possible reproductive impact of the flavonoid should be carefully considered in animal nutrition.

Oocyte-secreted factros regulate granulosa cell steroidogenesis

Zygote ◽  
1996 ◽  
Vol 4 (04) ◽  
pp. 317-321 ◽  
Author(s):  
Barbara C. Vanderhyden
Keyword(s):  
Cell Proliferation ◽  
Germ Cell ◽  
Granulosa Cell ◽  
Granulosa Cells ◽  
Follicular Fluid ◽  
Follicular Development ◽  
Inhibitory Factor ◽  
Preovulatory Follicles ◽  
Loss Of Contact

Investigations of strains of mice defective in germ cell development have revealed the importance of oocytes for the initial stages of folliculogenesis (Pellaset al., 1991; Huanget al., 1993). Various aspects of follicular development are dependent upon and/or influenced by the presence of oocytes, including granulosa cell proliferation (Vanderhydenet al., 1990, 1992) and cumulus expansion (Buccioneet al., 1990; Salustriet al., 1990; Vanderhydenet al., 1990; Vanderhyden, 1993). We are investigating the possibility that oocytes influence one of the primary functions of granulosa cells: steroidogenesis. In many species, granulosa cells removed from preovulatory follicles luteinisein vitro(Channinget al., 1982), presumably due to loss of contact with follicular luteinisation inhibitory factor(s). Indeed, follicular fluid can prevent granulosa cell luteinisationin vitro(Ledwitz-Rigbyet al., 1977). Follicular fluid, however, may simply be the medium for transport of factors secreted by oocytes to regulate granulosa cell activities.

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