Effects of cytochalasin B on DNA methylation and histone modification in parthenogenetically activated porcine embryos

Cyclophosphamide reduces gene transcriptional activity and embryo in vitro development by inhibiting NF-κB expression through decreasing AcH4K12

Cyclophosphamide (CTX), a widely used chemotherapeutic agent for cancer treatment, has been associated with long-term toxicity and detrimental effects on oocytes and ovaries, resulting in female reproductive dysfunction. This study aimed to investigate the potential impact of CTX on in vitro maturation (IVM) injury of porcine oocytes and subsequent embryonic development, as well as its effects on epigenetic modification and gene activation during early embryonic development. The results demonstrated that CTX treatment caused aberrant spindle structure and mitochondrial dysfunction during oocyte maturation, inducing DNA damage and early apoptosis, which consequently disrupted meiotic maturation. Indeed, CTX significantly reduced the in vitro developmental capacity of porcine embryos, and induced DNA damage and apoptosis in in vitro fertilization (IVF) blastocysts. Importantly, CTX induced abnormal histone modification of AcH4K12 in early porcine embryos. Moreover, addition of LBH589 before zygotic genome activation (ZGA) effectively increased AcH4K12 levels and restored the protein expression of NF-κB, which can effectively enhance the in vitro developmental potential of IVF embryos. The DNA damage and apoptosis induced by CTX compromised the quality of the blastocysts, which were recovered by supplementation with LBH589. This restoration was accompanied by down-regulation of BAX mRNA expression and up-regulation of BCL2, POU5F1, SOX2 and SOD1 mRNA expression. These findings indicated that CTX caused abnormal histone modification of AcH4K12 in early porcine embryos and reduced the protein expression of NF-κB, a key regulator of early embryo development, which may block subsequent ZGA processes.

LncRNA affects epigenetic reprogramming of porcine embryo development by regulating global epigenetic modification and the downstream gene SIN3A

The study of preimplantation development is of great significance to reproductive biology and regenerative medicine. With the development of high-throughput deep sequencing technology, it has been found that lncRNAs play a very important role in the regulation of embryonic development. In this study, key lncRNAs that regulate embryonic development were screened by analyzing the expression pattern of lncRNAs in porcine in vivo fertilization (IVV) embryos. By knocking down lncRNA expression in in vitro fertilization (IVF) embryos, we investigated its function and mechanism of regulating embryonic development. The results showed that the expression pattern of lncRNA was consistent with the time of gene activation. The lncRNAs were highly expressed in the 4-cell to blastocyst stage but barely expressed in the oocytes and 2-cell stage. So we speculated this part of lncRNAs may regulate gene expression. The lncRNA LOC102165808 (named lncT because the gene near this lncRNA is TFAP2C) was one of them. The knockdown (KD) of lncT inhibited embryonic development, resulting in decreased H3K4me3, H3K4me2, and H3K9me3, and increased DNA methylation. Meanwhile, RNAseq showed SIN3A was the top decreased gene in lncT-KD embryos. There was a severe blastocyst formation defect in SIN3A-KD embryos. Both lncT and SIN3A could affect NANOG and induce more cell apoptosis. In conclusion, the knockdown of lncT inhibits embryonic development by regulating H3K4me3, H3K4me2, DNA methylation, pluripotency gene, and apoptosis, and SIN3A is one of the downstream genes of lncT in regulating embryonic development.

Effects of dimethyl sulfoxide (DMSO) on DNA methylation and histone modification in parthenogenetically activated porcine embryos

Epigenetic mechanisms play an important role in oogenesis and early embryo development in mammals. Dimethyl sulfoxide (DMSO) is frequently used as a solvent in biological studies and as a vehicle for drug therapy. Recent studies suggest that DMSO detrimentally affects porcine embryonic development, yet the mechanism of the process in parthenogenetically activated porcine embryos has not been reported. In this study, we found that treatment of embryos with 1.5% DMSO significantly decreased the cleavage and blastocyst rates, total cell number of blastocysts and the anti-apoptotic gene BCL-2 transcription level; however, the percentage of apoptotic cells and the expression levels of the pro-apoptotic gene BAX were not changed. Treatment with DMSO significantly decreased the expression levels of DNMT1 , DNMT3a , DNMT3b , TET1 , TET2 , TET3 , KMT2C , MLL2 and SETD3 in most of the stages of embryonic development and increased 5-mC signals, while the staining intensity for 5-hmC had no change in porcine preimplantation embryos from 2-cell to the blastocyst stages. Meanwhile, DMSO decreased the level of H3K4me3 during the development of parthenogenetically activated porcine embryos. After treatment with DMSO, expression levels of the pluripotency-related genes POU5F1 and NANOG decreased significantly (P <0.01), whereas the imprinted gene H19 did not change (P >0.05). In conclusion, these results suggest that DMSO can affect genome-wide DNA methylation and histone modification by regulating the expression of epigenetic modification enzymes, and DMSO also influences the expression level of pluripotent genes. These dysregulations lead to defects in embryonic development.

Cycloleucine negatively regulates porcine oocyte maturation and embryo development by modulating N6-methyladenosine and histone modifications

Maturation of oocytes and early embryo development are regulated precisely by numerous factors at transcriptional and posttranslational levels through precise mechanisms. N6-methyladenosine (m⁶A) is the most common modification in mRNA which regulates RNA metabolism and gene expression. However, the role of RNA m⁶A on porcine oocyte maturation and early embryogenesis is largely unknown. Here, we found that oocytes treated with cycloleucine (CL), an RNA m⁶A inhibitor, express impaired cumulus expansion, increased production of reactive oxygen species (ROS) in the mitochondria, and delayed maturation of oocytes by disrupting spindle organization and chromosome alignment. Also, CL halted the development of embryos at the 4-cell stage and resulted in low-quality blastocysts. Furthermore, CL treatment decreased the RNA m⁶A, H3K4me3, and H3K9me3 levels, but increased the acetylation level of H4K16 during parthenogenetic embryonic development in pigs. Single-cell RNA-seq (scRNA-seq) analysis further revealed that CL treatment dramatically up-regulated the expression of metabolism-related genes (SLC16A1, and MAIG3 etc.) and maternal related genes, including BTG4, WEE2, and BMP15 among others, at the blastocyst stage. Taken together, inhibition of RNA m⁶A by CL impaired meiosis of oocytes and early embryonic development of porcine via RNA m⁶A methylation, histone modifications, and altering the expression of metabolism-related genes in blastocysts.

Helicobacter pylori regulates ILK to influence autophagy through Rac1 and RhoA signaling pathways in gastric epithelial cells

The ability of Helicobacter pylori to manipulate host autophagy is an important pathogenic mechanism. We found an inverse correlation between the expression of ILK and the autophagy marker protein LC3B in H. pylori-positive human samples, H. pylori-infected mice models and H. pylori-infected GES-1 cell lines. When the ILK-knockdown GES-1 cells were infected by H. pylori, CagA were significantly degraded, autophagosomes accumulation and autolysosomes formation were significantly increased, and LC3B protein levels and ratio of LC3BII to LC3BI were also remarkably upregulated. And chloroquine treatment increased LC3B levels in ILK-knockdown GES-1 cells. The expression levels of both Rac1 and RhoA were downregulated in GES-1 cells after H. pylori infection and were decreased in ILK-knockdown GES-1 cells. The mRNA and protein levels of PAK1, MLC, and LIMK were significantly decreased and cofilin mRNA and protein levels were significantly increased in GES-1 cells treated with the Rac1 inhibitor NSC 23766. The mRNA and protein levels of ROCK1, ROCK2, MLC, and LIMK1 were significantly reduced and cofilin mRNA and protein levels were significantly increased in GES-1 cells treated with the RhoA inhibitor CCG-1423. F-actin was significantly reduced in Rac1- or RhoA-inhibited GES-1 cells. F-actin depolymerization induced autophagosomes accumulation, autolysosomes formation, and the increase of LC3B levels in GES-1 cells. Therefore, these findings revealed that ILK could serve as a novel regulator to affect Rac1/PAK1 and RhoA/ROCKs signaling pathways, thereby influencing H. pylori-induced autophagy.

DNA methylation regulated by ascorbic acids in yak preimplantation embryo helps to improve blastocyst quality

DNA methylation as an important, essential epigenetic modification is critical for the successful development of mammalian embryos. In recent years, the important role of ascorbic acid (AA) as an irreplaceable cofactor for epigenetic regulation has been confirmed. However, the effect of AA on DNA methylation in preimplantation embryo development of plateau yak remains unknown. In this study, we explored whether AA can help regulates DNA methylation in yak preimplantation embryos to improve the blastocyst quality. First, our results indicate that the preimplantation of the yak still follows the classical pattern of DNA demethylation and remethylation, however, remethylation occurs in the blastocyst stage. Second, the unique expression pattern of the ten-eleven translocation enzyme (TET3) in the cytoplasm plays a key role in the demethylation mechanism. Third, in the blastocyst stage, the pluripotency gene CDX2 promoter region was in a hypomethylated state, and the POU5F1, SOX2, and NANOG promoter regions were in moderate methylation states. In addition, treatment with 50 μg/ml AA mainly improved the expression levels of DNMT1, DNMT3a, and TET3, ensured the establishment, maintenance and transition of 5-methylcytosine. After AA treatment, the methylation level of the pluripotency genes NANOG promoter regions was significantly reduced, and the mRNA transcript abundance of the pluripotency genes NANOG, POU5F1, and CDX2 was upregulated. In conclusion, our findings suggest that AA could increase blastocyst cell numbers by regulating DNA methylation of yak preimplantation embryos .