DNA Methylation Patterns Are Appropriately Established in the Sperm of Bulls Generated by Somatic Cell Nuclear Transfer

2011 ◽  
Vol 13 (2) ◽  
pp. 171-177 ◽  
Author(s):  
Christine Couldrey ◽  
David N. Wells ◽  
Rita S. F. Lee
2009 ◽  
Vol 21 (1) ◽  
pp. 113 ◽  
Author(s):  
C. Couldrey ◽  
M. P. Green ◽  
D. N. Wells ◽  
R. S. F. Lee

Cloning of domestic animals by somatic cell nuclear transfer (SCNT) has permitted the rescue of valuable genetics and has the potential to allow rapid dissemination of desirable traits in production animals through the use of cloned sires. Whilst cloned animals may show developmental deviations and aberrant DNA methylation suggestive of incomplete nuclear reprogramming, it is widely accepted that their offspring are normal, as any aberrant epigenetic marks are believed to be corrected on passage of the genome through the germline. We assessed the extent of reprogramming by comparing DNA methylation patterns in sperm of SCNT bulls (n = 4) with sperm from bulls generated by AI (n = 5) and with the nuclear donor somatic cells (adult skin fibroblasts). The genomic regions examined were 3 repetitive sequences (satellites 1, 2, and alpha) and CpG islands in 5 genes [HAND1, LIT1, MASH2, IGF2, Dickkopf-1(DKK-1)]. Semen was collected from 16-month-old bulls and assessed for volume, sperm number, morphology, and motility. DNA was extracted from washed sperm and somatic donor cells, bisulfite-treated and processed for quantification of CpG methylation using the Sequenom MassArray system. Methylation levels at individual CpG sites/groups of CpGs were compared between sample groups using the t-test with pooled variances. No apparent difference was detected in semen characteristics between SCNT and AI bulls. Sperm DNA methylation levels were very low in single copy genes with the exception of the CpG island in IGF2, which has previously been shown to be completely methylated in sperm. At all genomic regions examined, each CpG site or CpG groups were methylated to different levels, and each region had a distinctive profile, which was almost invariant between individual sperm samples from either the SCNT or AI bulls. In all sites examined, there were no significant differences in methylation profiles between sperm from SCNT and AI bulls. In contrast, DNA methylation profiles were significantly different between SCNT bull sperm and the donor cells. The exception was the CpG island in MASH2, which was essentially unmethylated in both. For the 3 satellite sequences along with LIT1, HAND1, and to a lesser extent, the DKK-1 region, DNA was significantly less methylated in sperm than in the donor cells. Only IGF2 was significantly more methylated in SCNT and AI sperm than in the donor cells at 10/25 CpG sites (P < 0.02). The results indicate that gametes from SCNT bulls had different epigenotypes from the donor somatic cells. This is the first molecular evidence that donor cell genomes have been reprogrammed in these SCNT bulls and that after going through the germline had acquired DNA methylation profiles that were similar to AI-derived bulls. It also suggests that any epigenetic aberrations that SCNT bulls may harbor are unlikely to be passed on to their offspring through their gametes. Supported by FRST contract C10X0311.


2018 ◽  
Vol 50 (4) ◽  
pp. 1376-1397 ◽  
Author(s):  
Yanhui Zhai ◽  
Zhiren Zhang ◽  
Hao Yu ◽  
Li Su ◽  
Gang Yao ◽  
...  

Background/Aims: DNA methylation and histone modifications are essential epigenetic marks that can significantly affect the mammalian somatic cell nuclear transfer (SCNT) embryo development. However, the mechanisms by which the DNA methylation affects the epigenetic reprogramming have not been fully elucidated. Methods: In our study, we used quantitative polymerase chain reaction (qPCR), Western blotting, immunofluorescence staining (IF) and sodium bisulfite genomic sequencing to examine the effects of RG108, a DNA methyltransferase inhibitor (DNMTi), on the dynamic pattern of DNA methylation and histone modifications in porcine SCNT embryos and investigate the mechanism by which the epigenome status of donor cells’ affects SCNT embryos development and the crosstalk between epigenetic signals. Results: Our results showed that active DNA demethylation was enhanced by the significantly improving expression levels of TET1, TET2, TET3 and 5hmC, and passive DNA demethylation was promoted by the remarkably inhibitory expression levels of DNMT1, DNMT3A and 5mC in embryos constructed from the fetal fibroblasts (FFs) treated with RG108 (RG-SCNT embryos) compared to the levels in embryos from control FFs (FF-SCNT embryos). The signal intensity of histone H3 lysine 4 trimethylation (H3K4me3) and histone H3 lysine 9 acetylation (H3K9Ac) was significantly increased and the expression levels of H3K4 methyltransferases were more than 2-fold higher expression in RG-SCNT embryos. RG-SCNT embryos had significantly higher cleavage and blastocyst rates (69.3±1.4%, and 24.72±2.3%, respectively) than FF-SCNT embryos (60.1±2.4% and 18.38±1.9%, respectively). Conclusion: Dynamic changes in DNA methylation caused by RG108 result in dynamic alterations in the patterns of H3K4me3, H3K9Ac and histone H3 lysine 9 trimethylation (H3K9me3), which leads to the activation of embryonic genome and epigenetic modification enzymes associated with H3K4 methylation, and contributes to reconstructing normal epigenetic modifications and improving the developmental efficiency of porcine SCNT embryos.


2015 ◽  
Vol 17 (5) ◽  
pp. 404-414 ◽  
Author(s):  
Hongliang Sun ◽  
Fenghua Lu ◽  
Peng Zhu ◽  
Xiaohua Liu ◽  
Mingming Tian ◽  
...  

2007 ◽  
Vol 75 (2) ◽  
pp. 250-264 ◽  
Author(s):  
Aaron J. Bonk ◽  
Rongfeng Li ◽  
Liangxue Lai ◽  
Yanhong Hao ◽  
Zhonghua Liu ◽  
...  

2008 ◽  
Vol 53 (13) ◽  
pp. 1996-2001 ◽  
Author(s):  
Jie Chen ◽  
DongJie Li ◽  
YanQin Liu ◽  
Cui Zhang ◽  
YunPing Dai ◽  
...  

2019 ◽  
Vol 31 (1) ◽  
pp. 148
Author(s):  
Y. H. Zhai ◽  
X. L. An ◽  
Z. R. Zhang ◽  
S. Zhang ◽  
Z. Y. Li

During fertilization, the parental genome undergoes extensive demethylation. Global DNA demethylation is a hallmark of epigenetic reprogramming. Embryos engage non-canonical DNA methylation maintenance mechanisms to ensure inheritance of exceptional germline features. However, the mechanisms ensuring demethylation resistance in light of global reprogramming remain poorly understood. TRIM28 is a maternal-effect factor that controls genomic imprinting during early embryonic reprogramming. In this study, cytoplasmic injections of siRNA were performed into oocytes matured in vitro for 26h to interfere with the expression of TRIM28 in oocytes. The injected oocytes were continually matured in vitro until 42h and used to construct somatic cell nuclear transfer (SCNT) embryos. During 2-cell to blastocyst stages, the expression of development-related genes (NANOG, POU5F1, CDX2, BAX, and BCL2), maternal imprinting genes (IGF2, DIO3, PLAGL1, and DLK1), paternal imprinting genes (H19 and PEG3), TRIM28-recruitment complex-associated genes (ZFP57, PGC7, SETDB1, and DNMT), and epigenetic chromatin modification enzymes were detected by quantitative PCR in the constructed TRIM28-interfered SCNT embryos. The DNA methylation levels in the promoter regions of the imprinted genes (H19 and IGF2) and chromatin repeats (PRE-1 and SATELLITE) were analysed by sodium bisulfite genomic sequencing. The results showed that the TRIM28-interfered SCNT embryos had significantly lower cleavage and blastocyst rates (53.9±3.4% and 12.1±4.3%, respectively) than those in control SCNT embryos (64.8±2.7% and 18.8±1.9%, respectively). The expression levels of development-related genes (NANOG and POU5F1) and TRIM28-recruited transcriptional repression complex-associated genes (PGC7, ZFP57, and DNMT1) in the 4-cell stage were significantly reduced (P&lt;0.05). The imprinted genes were significantly up-regulated (P&lt;0.05) from the 2-cell to blastocyst stage in constructed TRIM28-interfered SCNT embryos, except H19 at the 2-cell and blastocyst stage decreased remarkably (P&lt;0.05). The DNA methylation levels of IGF2 decreased 2-fold from the 2-cell to blastocyst stage in TRIM28-interfered SCNT embryos. The PRE-1 and SATELLITE had a remarkably lower (P&lt;0.05) methylation levels in the TRIM28-interfered 2-cell embryos than in control SCNT embryos. The cluster analysis showed some of the chromatin modification enzymes had abnormal expression in the TRIM28-interfered SCNT embryos, especially in the 8-cell stage, where 48 enzymes were significantly decreased (P&lt;0.05). The down-regulation enzymes were mainly clustered in the histone H3K4 methyl transferase and histone acetylase. These results indicate that down-regulation of maternal TRIM28 breaks the steady-state of genomic methylation at a particular locus of the imprinted gene, disrupts the expression of imprinted gene and epigenetic modifications enzymes, and is detrimental to normal development of SCNT embryos. Maternal TRIM28 is needed in maintaining a stable state of genomic methylation and epigenetic modification state during SCNT embryo development.


2011 ◽  
Vol 13 (4) ◽  
pp. 307-314 ◽  
Author(s):  
Fei Gao ◽  
Shengting Li ◽  
Lin Lin ◽  
Jian Li ◽  
Yonglun Luo ◽  
...  

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