Development Of Somatic Cell Nuclear Transfer Embryos Research Articles

MicroRNA-125b is a key epigenetic regulatory factor that promotes nuclear transfer reprogramming

Somatic cell nuclear transfer (SCNT)-mediated reprogramming is a rapid, efficient, and sophisticated process that reprograms differentiated somatic cells to a pluripotent state. However, many factors in this elaborate reprogramming process remain largely unknown. Here, we report that the microRNA (miR) miR-125b is an important component of SCNT-mediated reprogramming. Luciferase reporter assay, quantitative PCR, and Western blotting demonstrated that miR-125b directly binds the 3′-untranslated region of SUV39H1, encoding the histone-lysine N-methyltransferase SUV39H1, to down-regulate histone H3 lysine-9 tri-methylation (H3K9me3) in SCNT embryos. Furthermore, the miR-125b/SUV39H1 interaction induced loss of SUV39H1-mediated H3K9me3, caused heterochromatin relaxation, and promoted the development of SCNT embryos. Transcriptome analyses of SCNT blastomeres indicated that HNF1 homeobox B (HNF1B), a gene encoding a transcription factor downstream of and controlled by the miR-125b/SUV39H1 axis, is important for conferring developmental competence on preimplantation embryos. We conclude that miR-125b promotes SCNT-mediated nuclear reprogramming by targeting SUV39H1 to decrease the deposition of repressive H3K9me3 modifications.

Coexpression analysis identifies nuclear reprogramming barriers of somatic cell nuclear transfer embryos.

The success of cloned animal “Dolly Sheep” demonstrated the somatic cell nuclear transfer (SCNT) technique holds huge potentials for mammalian asexual reproduction. However, the extremely poor development of SCNT embryos indicates their molecular mechanism remain largely unexplored. Deciphering the spatiotemporal patterns of gene expression in SCNT embryos is a crucial step toward understanding the mechanisms associated with nuclear reprogramming. In this study, a valuable transcriptome recourse of SCNT embryos was firstly established, which derived from different inter-/intra donor cells. The gene co-expression analysis identified 26 cell-specific modules, and a series of regulatory pathways related to reprogramming barriers were further enriched. Compared to the intra-SCNT embryos, the inter-SCNT embryos underwent only complete partially reprogramming. As master genome trigger genes, the transcripts related to TFIID subunit, RNA polymerase and mediators were incomplete activated in inter-SCNT embryos. The inter-SCNT embryos only wasted the stored maternal mRNA of master regulators, but failed to activate their self-sustained pathway of RNA polymerases. The KDM family of epigenetic regulator also seriously delayed in inter-SCNT embryo reprogramming process. Our study provided new insight into understanding of the mechanisms of nuclear reprogramming.

MicroRNA-148a overexpression improves the early development of porcine somatic cell nuclear transfer embryos.

Incomplete epigenetic reprogramming of donor cell nuclei is one of the main contributors to the low efficiency of somatic cell nuclear transfer (SCNT). To improve the success of SCNT, somatic cell DNA methylation levels must be reduced to those levels found in totipotent embryonic cells. Recent studies have demonstrated that miR-148a can affect DNA methylation via DNMT1 modulation in various cancers. Therefore, the focus of this study was to examine the influence of miR-148a on DNA methylation in donor cells and in SCNT embryo development. Thus, a stable cell line overexpressing miR-148a was established and used to produce SCNT embryos. Upon examination, DNMT1 was found to be a miR-148a target in porcine fetal fibroblasts (PFF). Furthermore, miR-148a overexpression in PFFs significantly decreased DNMT1 expression and global DNA methylation levels (P < 0.05). Moreover, miRNA-148a expression levels in SCNT embryos were significantly lower at the 2-cell and 4-cell stages when compared to IVF and parthenogenetic embryos. The group overexpressing miRNA-148a also showed a significant increase in blastocyst formation and total cell numbers (P < 0.05). Additionally, miR-148a overexpression altered the immunofluorescence signal of 5-mC and H3K9ac, and enhanced pluripotent gene (Oct4 and Nanog) expression levels during embryo development. These results indicate that miR-148a overexpression enhances the developmental potential of SCNT embryos and modifies epigenetic status.

DOT1L inhibitor improves early development of porcine somatic cell nuclear transfer embryos.

Incomplete epigenetic reprogramming of the genome of donor cells causes poor early and full-term developmental efficiency of somatic cell nuclear transfer (SCNT) embryos. Previous research indicate that inhibition of the histone H3 K79 methyltransferase DOT1L, using a selective pharmacological inhibitor EPZ004777 (EPZ), significantly improved reprogramming efficiency during the generation of mouse induced pluripotent stem cells. However, the roles of DOT1L in porcine nuclear transfer-mediated cellular reprogramming are not yet known. Here we showed that DOT1L inhibition via 0.5 nM EPZ treatment for 12 or 24 h significantly enhanced the blastocyst rate of SCNT embryos and dramatically reduced the level of H3K79me2 during SCNT 1-cell embryonic development. Additionally, H3K79me2 level in the EPZ-treated SCNT embryos was similar to that in in vitro fertilized embryos, suggesting that DOT1L-mediated H3K79me2 is a reprogramming barrier to early development of porcine SCNT embryos. qRT-PCR analysis further demonstrated that DOT1L inactivation did not change the expression levels of DOT1L itself but increased the expression levels of POU5F1, LIN28, SOX2, CDX2 and GATA4 associated with pluripotency and early cell differentiation. In conclusion, DOT1L inhibitor improved early developmental efficiency of porcine SCNT embryos probably via inducing the increased expression of genes important for pluripotency and lineage specification.

IWP2 impairs the development of porcine somatic cell nuclear transfer embryos via Wnt signaling pathway inactivation.

Wnt signaling is critical in embryonic development and post-embryonic tissue homeostasis. The aim of the present study was to evaluate the expression levels of canonical Wnt signaling genes in porcine somatic cell nuclear transfer (SCNT) embryos. Quantitative polymerase chain reaction analysis was performed in porcine SCNT embryos, and the results indicated that the temporal expression patterns of canonical signaling genes were similar between in vivo and SCNT embryos from the 2-cell to the blastocyst stage. In addition, aberrant expression in a small number of Wnt signaling genes in SCNT embryos was identified. IWP2, an inhibitor of Wnt processing, was applied to the culture of SCNT embryos. The Wnt signaling pathway in the SCNT blastocysts may be inactivated via IWP2 treatment, reflecting the low expression levels of c-Myc and peroxisome proliferator-activated receptor δ. Furthermore, blastocyst hatching was damaged by IWP2 treatment. These findings indicate that the canonical Wnt signaling pathway is important for SCNT embryo development.

Effects of embryo-derived exosomes on the development of bovine cloned embryos.

The developmental competence of in vitro cultured (IVC) embryos is markedly lower than that of their in vivo counterparts, suggesting the need for optimization of IVC protocols. Embryo culture medium is routinely replaced three days after initial culture in bovine, however, whether this protocol is superior to continuous nonrenewal culture method under current conditions remains unclear. Using bovine somatic cell nuclear transfer (SCNT) embryos as the model, our results showed that compared with routine renewal treatment, nonrenewal culture system significantly improved blastocyst formation, blastocyst quality (increased total cell number, decreased stress and apoptosis, enhanced Oct-4 expression and ratio of ICM/TE), as well as following development to term. Existence and function of SCNT embryo-derived exosomes were then investigated to reveal the cause of impaired development induced by culture medium replacement. Exosomes were successfully isolated through differential centrifugation and identified by both electron microscopy and immunostaining against exosomal membrane marker CD9. Supplementation of extracted exosomes into freshly renewed medium significantly rescued not only blastocyst formation and quality (in vitro development), but also following growth to term (in vivo development). Notably, ratio of ICM/TE and calving rate were enhanced to a similar level as that in nonrenewal group. In conclusion, our results for the first time indicate that 1: bovine SCNT embryos can secrete exosomes into chemically defined culture medium during IVC; 2: secreted exosomes are essential for SCNT blastocyst formation, blastocyst quality, and following development to term; 3: removal of exosomes induced by culture medium replacement impairs SCNT embryo development, which can be avoided by nonrenewal culture procedure or markedly recovered by exosome supplementation.

Effects of Trichostatin A and PXD101 on the In Vitro Development of Mouse Somatic Cell Nuclear Transfer Embryos.

The low success rate of animal cloning by somatic cell nuclear transfer (SCNT) is believed to be associated with aberrant epigenetic nuclear reprogramming. It has been demonstrated that treatment with histone deacetylase inhibitors (HDACis) enhances developmental potential of SCNT embryos. Previous studies in many species revealed that treatment of SCNT embryos with trichostatin A (TSA)-an HDACi-significantly enhances the in vitro development of SCNT embryos. In this study, we compared two different SCNT protocols with TSA and investigate, for the first time, the effect of another new HDACi, PXD101 (belinostat), on in vitro development of mouse SCNT embryo. Rates of blastocyst development in mouse SCNT embryos treated with either 5 nM TSA during (6 hours) and after (4 hours) activation (39.1%) or with 50 nM PXD101 during (6 hours) and after (4 hours) activation (40.2%) were significantly higher than those of nontreated SCNT embryos (11.5%) and both treatments also significantly improved the subsequent establishment of NT-ESCs in comparison with the nontreated group (38.1% and 40.9% vs. 11.8%). In conclusion, we optimized the TSA concentration and treatment timing and, for the first time, investigated the effect of PXD101 on mouse development of SCNT embryos and establishment of NT-ESCs.

Ascorbic acid increases demethylation in somatic cell nuclear transfer embryos of the pig (Sus scrofa).

ObjectiveInvestigated the effect and mechanism of ascorbic acid on the development of porcine embryos produced by somatic cell nuclear transfer (SCNT).MethodsPorcine embryos were produced by SCNT and cultured in the presence or absence of ascorbic acid. Ten-eleven translocation 3 (TET3) in oocytes was knocked down by siRNA injection. After ascorbic acid treatment, reprogramming genes were analyzed by realtime reverse transcription-polymerase chain reaction (RT-PCR). Furthermore, relative 5-methylcytosine and 5-hydroxymethylcytosine content in pronucleus were detected by realtime PCR.ResultsAscorbic acid significantly increased the development of porcine embryos produced by SCNT. After SCNT, transcript levels of reprogramming genes, Pou5f1, Sox2, and Klf were significantly increased in blastocysts. Furthermore, ascorbic acid reduced 5-methylcytosine content in pronuclear embryos compared with the control group. Knock down of TET3 in porcine oocytes significantly prevents the demethylation of somatic cell nucleus after SCNT, even if in the presence of ascorbic acid.ConclusionAscorbic acid enhanced the development of porcine SCNT embryos via the increased TET3 mediated demethylation of somatic nucleus.

Scriptaid Upregulates Expression of Development-Related Genes, Inhibits Apoptosis, and Improves the Development of Somatic Cell Nuclear Transfer Mini-Pig Embryos.

The present study was undertaken to investigate the mechanisms by which Scriptaid treatment improves the developmental competence of somatic cell nuclear transfer (SCNT) mini-pig embryos in vitro. We found that treatment with 500 nmol/L Scriptaid for 15 hours significantly improved the development of mini-pig SCNT embryos. Compared with the control group, the blastocyst rate was higher (18.3% vs. 10.7%; p < 0.05). The acetylation level on H3K14 of the Scriptaid-treated group was higher compared with the control group in SCNT embryos at two-cell, four-cell, and blastocyst stages (p < 0.05). After Scriptaid treatment, histone deacetylase gene HDAC5 expression level was significantly decreased in four-cell embryos and blastocysts, while the expression levels of the embryos' development-related genes AKT, Oct4, and apoptosis inhibited gene PGC-1α were significantly increased in blastocysts (p < 0.05). The number of apoptotic cells per blastocyst in the Scriptaid-treated group was lower compared with the control group (p < 0.05). These results indicate that Scriptaid repressed HDCA5 gene expression, increased the acetylation level of H3K14, upregulated the expression of AKT, Oct4, and PGC-1α genes, improved embryos' development, and reduced apoptosis, which favors development of the SCNT mini-pig embryos to blastocysts.

The HDAC Inhibitor LAQ824 Enhances Epigenetic Reprogramming and In Vitro Development of Porcine SCNT Embryos

Background/Aims: Hypoacetylation caused by aberrant epigenetic nuclear reprogramming results in low efficiency of mammalian somatic cell nuclear transfer (SCNT). Many epigenetic remodeling drugs have been used in attempts to improve in vitro development of porcine SCNT embryos. In this study, we examined the effects of LAQ824, a structurally novel histone acetylase inhibitor, on the nuclear reprogramming and in vitro development of porcine SCNT embryos. Methods: LAQ824 treatment was supplemented during the culture of SCNT embryos. The reprogramming levels were measured by immunofluorescence and quantified by image J software. Relative expression levels of 18 genes were analyzed by quantitative real-time PCR. Results: 100 nM LAQ824 treatment of post-activation SCNT embryos for 24 h significantly improved the subsequent blastocyst formation rate. The LAQ824 treatment enhanced histone 3 lysine 9 (H3K9) levels, histone 4 lysine 12 (H4K12) levels, and reduced global DNA methylation levels as well as anti-5-methylcytosine (5-mC) at the pseudo-pronuclear and 2-cell stages. Furthermore, LAQ824 treatment positively regulated the mRNA expression of genes for histone acetylation (HAT1, HDAC1, 2, 3, and 6), DNA methylation (DNMT1, 3a and 3b), development (Pou5f1, Nanog, Sox2, and GLUT1) and apoptosis (Bax, Bcl2, Caspase 3 and Bak) in blastocysts. Conclusion: Optimum exposure (100 nM for 24 h) to LAQ824 post-activation improved the in vitro development of porcine SCNT embryos by enhancing levels of H3K9 and H4K12, reducing 5-mC, and regulating gene expression.

Birth of Cloned Microminipigs Derived from Somatic Cell Nuclear Transfer Embryos That Have Been Transiently Treated with Valproic Acid.

In our previous study, we found that treatment of miniature pig somatic cell nuclear transfer (SCNT) embryos with 4 mM valproic acid (VPA), a histone deacetylase inhibitor, for 48 hours after activation enhanced blastocyst formation rate and octamer-binding transcription factor-3/4 (Oct-3/4) gene expression at the late blastocyst stage; however, the production of viable cloned pups failed, when those VPA-treated SCNT embryos were transferred to recipients. This failure suggests that the present VPA treatment is suboptimal. In the present study, we explored the optimal conditions for VPA to have beneficial effects on the development of SCNT embryos. When miniature pig SCNT embryos were treated with 8 mM VPA for 24 hours after activation, both the rates of blastocyst formation and blastocysts expressing the Oct-3/4 gene were significantly (p < 0.05) improved. A similar increase in blastocyst formation was also observed when microminipig-derived cells were used as SCNT donors. Five cloned piglets were obtained after the transfer of 152 microminipig SCNT embryos that had been treated with 8 mM VPA for 24 hours. The results indicated that a short duration of treatment with VPA improves the development of both miniature pig and microminipig SCNT embryos, possibly via an enhanced reprogramming mechanism.

Tauroursodeoxycholic acid improves pre-implantation development of porcine SCNT embryo by endoplasmic reticulum stress inhibition

The aim of this study is to investigate whether endoplasmic reticulum (ER) stress attenuation could improve porcine somatic cell nuclear transfer (SCNT) embryo developmental competence. We treated porcine SCNT embryos with TUDCA (tauroursodeoxycholic acid, an inhibitor of ER stress) and/or TM (tunicamycin, an ER stress inducer), and examined embryonic developmental potential, embryo quality, the levels of ER stress markers (XBP1 protein and mRNA) and apoptosis-related-genes (BAX and BCL2 mRNA). Immunostaining detected X-box-binding protein (XBP1), a key gene regulator during ER stress, at all stages of SCNT embryo development. Embryo development analysis revealed that TUDCA treatment markedly increased (p<0.05) blastocyst formation rate, total cell number and inner cell mass (ICM) cell number compared to untreated control group. The TUDCA and TM groups showed significant alterations in XBP1 protein and XBP1-s mRNA levels compared to controls (lower and higher, respectively; p<0.05). Also, TUDCA treatment reduced oxidative stress by up-regulation of the antioxidant, GSH. TUNEL assay showed that TUDCA treatment significantly reduced apoptosis in porcine SCNT blastocysts confirmed by decreased pro-apoptotic BAX and increased anti-apoptotic BCL2 mRNA levels. Collectively, our results indicated that TUDCA can enhance the developmental potential of porcine SCNT embryos by attenuating ER-stress and reducing apoptosis.

Mitochondria-targeted DsRed2 protein expression during the early stage of bovine somatic cell nuclear transfer embryo development

Somatic cell nuclear transfer (SCNT) has been widely used as an efficient tool in biomedical research for the generation of transgenic animals from somatic cells with genetic modifications. Although remarkable advances in SCNT techniques have been reported in a variety of mammals, the cloning efficiency in domestic animals is still low due to the developmental defects of SCNT embryos. In particular, recent evidence has revealed that mitochondrial dysfunction is detected during the early development of SCNT embryos. However, there have been relatively few or no studies regarding the development of a system for evaluating mitochondrial behavior or dynamics. For the first time, in mitochondria of bovine SCNT embryos, we developed a method for the visualization of mitochondria and expression of fluorescence proteins. To express red fluorescence in mitochondria of cloned embryos, bovine ear skin fibroblasts, nuclear donor, were stably transfected with a vector carrying mitochondria-targeting DsRed2 gene tagged with V5 epitope (mito-DsRed2-V5 tag) using lentivirus-mediated gene transfer because of its ability to integrate in the cell genome and the potential for long-term transgene expression in the transduced cells and their dividing cells. From western blotting analysis of V5 tag protein using mitochondrial fraction and confocal microscopy of red fluorescence using SCNT embryos, we found that the mitochondrial expression of the mito-DsRed2 protein was detected until the blastocyst stage. In addition, according to image analysis, it may be suggested possible use of the system for visualization of mitochondrial localization and evaluation of mitochondrial behaviors or dynamics in early development of bovine SCNT embryos.

Iloprost supports early development of in vitro-produced porcine embryos through activation of the phosphatidylinositol 3-kinase/AKT signalling pathway

Despite evidence of the presence of prostaglandin (PG) I2 in mammalian oviducts, its role in early development of in vitro-produced (IVP) embryos is largely unknown. Thus, in the present study we examined the effects of iloprost, a PGI2 analogue, on the in vitro developmental competence of early porcine embryos and the underlying mechanism(s). To examine the effects of iloprost on the development rate of IVF embryos, iloprost was added to the in vitro culture (IVC) medium and cultured for 6 days. Supplementation of the IVC medium with iloprost significantly improved developmental parameters, such as blastocyst formation rate, the trophectoderm:inner cell mass ratio and cell survival in IVF and parthenogenetically activated (PA) embryos. In addition, post-blastulation development into the expanded blastocyst stage was improved in iloprost-treated groups compared with controls. Interestingly, the phosphatidylinositol 3-kinase (PI3K)/AKT signalling pathway was significantly activated by iloprost supplementation in a concentration-dependent manner (10-1000nM), and the beneficial effects of iloprost on the early development of porcine IVF and PA embryos was completely ablated by treatment with 2.5μM wortmannin, a PI3K/AKT signalling inhibitor. Importantly, expression of the PI3K/AKT signalling pathway was significantly reduced in somatic cell nuclear transfer (SCNT) compared with IVF embryos, and iloprost supported the early development of SCNT embryos, as was the case for IVF and PA embryos, suggesting a consistent effect of iloprost on the IVC of IVP porcine embryos. Together, these results indicate that iloprost can be a useful IVC supplement for production of IVP early porcine embryos with high developmental competence.

Effects of Insulin-like Growth Factor-1 on Development of Somatic Cell Cloned Bovine Embryos

The aim of this study was to assess the effect of insulin-like growth factor-1 (IGF-1) on the developmental competence of somatic cell nuclear transfer (SCNT) bovine embryos. First, the expression levels of IGF-1 receptor (IGF-1R) and IGF-1 in the oocytes and embryos of different developmental stages were examined. Then the effects of exogenous IGF-1 on the development of SCNT embryos were evaluated both in vitro and in vivo. The results showed that IGF-1 was not expressed in both IVF and SCNT embryos, whereas IGF-1R could be detected throughout the preimplantation stages in both protein and mRNA levels. Also, exogenous IGF-1 had no obvious impact on the developmental competence of IVF embryos. However, it could improve the developmental competence of SCNT embryos in terms of blastocyst developmental rate (31.3% vs. 43.2%, p < 0.05), total cell number (93.0 ± 9.9 vs. 101.0 ± 9.8, p < 0.05), ratio of inner cell mass (ICM) to trophectoderm (TE) (0.29 ± 0.006 vs. 0.39 ± 0.005, p < 0.05), and apoptosis index in day 7 blastocysts (2.5 ± 0.22 vs. 8.7 ± 0.41, p < 0.05) compared to the control group. Although no statistical difference in pregnancy rate and birth rate was observed after embryo transfer, there was an upward tendency in both examined terms in the IGF-1-supplemented group when compared with the control group. In conclusion, the present study showed that supplementing exogenous IGF-1 to the culture medium has an obvious positive effect on the development competence of SCNT embryos.

Placental developmental defects in cloned mammalian animals

The cloning technique, also called somatic cell nuclear transfer (SCNT), has been successfully established and gradually applied to various mammalian species. However, the developmental rate of SCNT mammalian embryos is very low, usually at 1% to 5%, which limits the application of SCNT. Placental developmental defects are considered as the main cause of SCNT embryo development inhibition. Almost all of SCNT-derived mammalian placentas exhibit various abnormalities, such as placental hyperplasia, vascular defects and umbilical cord malformation. Mechanistically, these abnormalities result from failure of establishment of correct epigenetic modification in the trophectoderm genome, which leads to erroneous expression of important genes for placenta development-related, particularly imprinted genes. Consequently, aberrant imprinted gene expression gives rise to placental morphologic abnormalities and functional defects, therefore decreases developmental competence of cloned embryos. Currently, although numerous methods that can improve the developmental ability of SCNT-derived embryos have been reported, most of them are unable to substantially enhance the success rate of SCNT due to failure to eliminate the placental development defects. In this review, we summarize placental abnormalities and imprinted gene expression in mammalian cloning, and propose directions for the future research aiming to improve the cloning efficiency.

Methyl-CpG-Binding Protein 2 Improves the Development of Mouse Somatic Cell Nuclear Transfer Embryos.

Methyl-CpG-binding domain proteins (MBPs) connect DNA methylation and histone modification, which are the key changes of somatic cell reprogramming. Methyl-CpG-binding protein 2 (MeCP2) was the first discovered MBP that has been extensively studied in the neurodevelopmental disorder Rett syndrome. However, a role for MeCP2 during cellular reprogramming associated with somatic cell nuclear transfer (SCNT) has not been examined. In this study, we discovered that MeCP2 expression was significantly lower in embryos generated by SCNT compared with those generated by intracytoplasmic sperm injection (ICSI). We genetically modified mouse embryonic fibroblasts (MEFs) to overexpress MeCP2 and serve as donor cells for nuclear transfer (NT) to investigate the effects of MeCP2 on preimplantation development of SCNT embryos. The blastocyst rate (35.71%) of MeCP2 overexpressed embryos (NT(+)) was significantly greater than in nontransgenic embryos (NT(-), 24.29%). Furthermore, immunofluorescence experiments revealed that 5-methylcytosine (5mC) was transferred to 5-hydroxymethylcytosine (5hmC) to a greater extent in NT(+) embryos than in NT(-) embryos. Real-time PCR evaluation of gene expression also showed that embryonic development-associated genes, such as Oct4 and Nanog, were significantly higher in the NT(+) group compared to the NT(-) group. Collectively, these results suggested that MeCP2 facilitated Tet3 activity, enhanced expression of pluripotency-related genes, and eventually improved the development of NT embryos. Finally, we performed chromatin immunoprecipitation to identify direct targets of MeCP2 and constructed a protein interaction network to elucidate several putative MeCP2 targets.

Supplementation with spermine during in vitro maturation of porcine oocytes improves early embryonic development after parthenogenetic activation and somatic cell nuclear transfer.

Spermine plays an important role in protection from reactive oxygen species (ROS) in bacteria, yeast, and mammalian cells, but there are few studies on the effects of spermine on porcine oocyte maturation and subsequent embryo development. The aim of this study was to determine the effects of spermine on in vitro maturation (IVM) of porcine oocytes and their developmental competence after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT). We evaluated nuclear maturation, intracellular glutathione (GSH), and ROS levels in oocytes, and their subsequent embryonic development, as well as gene expression in mature oocytes, cumulus cells, and PA blastocysts. After treatment with various concentrations of spermine in IVM culture medium, there was no significant difference in nuclear maturation rate. However, spermine treatment groups (10- 500 µM) showed significantly increased intracellular GSH levels and decreased ROS levels compared to the control ( < 0.05). Furthermore, 10 µM spermine supported significantly higher blastocyst formation rates after PA than the control group ( < 0.05). According to the optimal condition from the PA results, we investigated the effects of 10 µM spermine on SCNT, and it also significantly improved blastocyst formation rates compared with the control group ( < 0.05). In evaluating the effects of 10 µM spermine on gene expression, there was significantly lower expression of a proapoptotic gene () and higher expression of an antiapoptotic gene () in cumulus cells ( < 0.05). was increased in spermine-treated oocytes. Levels of transcription for and were significantly increased in PA blastocysts. In conclusion, 10 µM spermine supplementation during IVM improved the development of porcine PA and SCNT embryos by increasing intracellular GSH, scavenging ROS levels, and regulating gene expression.

Effect of Cell Cycle Interactions and Inhibition of Histone Deacetylases on Development of Porcine Embryos Produced by Nuclear Transfer.

The aim of this study was to evaluate if the positive effects of inhibiting histone deacetylase enzymes on cell reprogramming and development of somatic cell nuclear transfer (SCNT) embryos is affected by the cell cycle stage of nuclear donor cells and host oocytes at the time of embryo reconstruction. SCNT embryos were produced with metaphase II (MII) or telophase II (TII) cytoplasts and nuclear donor cells that were either at the G1-0 or G2/M stages. Embryos reconstructed with the different cell cycle combinations were treated or not with the histone deacetylase inhibitor (HDACi) Scriptaid for 15 h and then cultured in vitro for 7 days. Embryos reconstructed with MII-G1-0 and TII-G2/M developed to the blastocyst stage with a higher frequency compared to the other groups, confirming the importance of cell cycle interactions on cell reprogramming and SCNT embryo development. Treatment with HDACi improved development of SCNT embryos produced with MII but not TII cytoplasts, independently of the cell cycle stage of nuclear donor cells. These findings provide evidence that the positive effect of HDACi treatment on development of SCNT embryos depends upon cell cycle interactions between the host cytoplast and the nuclear donor cells.

Effects of DNA methyltransferase inhibitor RG108 on methylation in buffalo adult fibroblasts and subsequent embryonic development following somatic cell nuclear transfer.

Buffalo are characteristic livestock of the Guangxi Zhuang Autonomous Region of China, but their low reproductive capacity necessitates the use of somatic cell nuclear transfer (SCNT). We investigated the effects of RG108 on DNA methylation in buffalo adult fibroblasts, and on subsequent SCNT embryo development. RG108 treatment (0, 5, 10, 20, and 100 mM) had no effect on cell morphology, viability, or karyotype (2n = 48), and cell growth followed a typical "S" curve. Immunohistochemistry showed that relative DNA methylation gradually decreased as RG108 concentration increased, and was significantly lower in the 20 and 100 mM groups compared to the 0, 5, and 10 mM treatments (0.94 ± 0.03 and 0.92 ± 0.05 vs 1.0 ± 0.02, 0.98 ± 0.05, and 0.98 ± 0.09, respectively; P < 0.05). Quantitative polymerase chain reaction revealed that DNMT1 gene expression of fibroblasts administered 10, 20, and 100 mM RG108 was significantly lower than those in the 0 and 5 mM groups (0.2 ± 0.05, 0.18 ± 0.07, and 0.3 ± 0.09 vs 1.0 ± 0.12 and 1.4 ± 0.12, respectively; P < 0.05). Treatment with 20 mM RG108 resulted in the lowest expression levels. Fibroblasts incubated with 20 mM RG108 for 72 h were used as donor cells to generate SCNT embryos. A greater number of such embryos developed into blastocysts compared to the non-treated group (28.9 ± 3.9 vs 15.3 ± 3.4%; P < 0.05). RG108 treatment can modify DNA methylation in buffalo adult fibroblasts and promote development of subsequent SCNT embryos.