During early embryo development, Oct-4 is an important transcription factor for the early differentiation. The present study was first examined methylation status in distal enhancer and promoter region of Oct-4 during mouse pre-implantation embryo development. In oocyte and sperm, high methylation was observed in both distal and proximal of promoter in Oct-4. Following fertilization, relatively high methylation level remained until 8-cell stage embryos, but decreased at the morula and blastocyst stage. Specific gene knock down of Oct-4 by siRNA injection into zygote induced higher methylation rates of both distal and proximal region ofpromoter of Oct-4. These results suggest a functional link between the DNA methylation status of distal and promoter region in the Oct-4 gene and the gene sequence-specific transcriptional silencing by exogenous siRNA injection during mouse pre- implantation embryos.

Transforming growth factor-β (TGF-β) has been shown to have a positive effect on in vitro fertilization (IVF) and has been reported to stimulate meiosis at follicular level in variety of species. The study was designed to determine the expression patterns of TGF-β1, TGF-β receptors type Ⅰ, Ⅱ and Smads gene in bovine oocytes and embryos. TGF-β1 and their receptors were observed in the unfertilized oocytes. TGF-β1 and type Ⅱ receptor were not expressed at the blastocyst stage, however, only type I receptor was exclusively observed at the same stage. The blastocyst stage, in particular, showed high levels of mRNA expression patterns containing a TGF-β type Ⅰ receptor. The mRNA expression pattern of Smad 2 at all stages of embryonic development was similar in all respect with TGF-β1 type I receptor. On the contrary, Smad 3 and 4 were expressed with high and low level mRNA at the blastocyst stage. In conclusion, it is suggested that TGF-β signaling may be regarded as an important entity during the preimplantation embryo development.

Autophagy is an evolutionarily conserved lysosomal pathway for degrading cytoplasmic proteins, macromolecules, and organelles, in addition to recycling protein and ATP synthesis. Although programmed cell death (PCD) is very important during embryogenesis, the mechanism underlying the dynamic development during this process remains largely unknown. In order to obtain insights into autophagy and it's relation with apoptosis in early embryo development, we first evaluated LC3 gene expression levels in mouse embryos developing in vitro. qRT-PCR revealed high expression levels from 1- to 4 cell stage embryo, and then expression decreased during morula and blastocyst formation. Indirect immunocytochemistry showed protein synthesis of LC3 in these stage embryos. Introducing of autophagy inhibitor, 3-MA (2mM) significantly decreased both developmental rate (54.85±11.0%) and total cell number (n=71±8), but increased apoptosis rate (5.68± 1.9%) at the blastocyst. Real time RT-PCR confirmed reduced expression of selected autophagy related genes, including ULK1, Atg4A, B, C, D, Atg5, Atg8, Gabarap, Atg9A, B and Atg16L. Treatment of autophagy inducer, rapamycin (50 ng/㎖) increased both mRNA expression and protein synthesis of LC3 and apoptosis rate (16.11±3.42%), but decreased developmental rates (50.16±9.78) and total cell numbers (n=60±7) as compared to control developmental rate (70.74±12.9%), Total cell number (89.8±9) and apoptotic cell death (1.11±0.7%). These results suggest that autophagy is related with apoptosis in mouse embryo, which possibly give a role for early development.

Mitochondria are important regulators of both apoptosis and autophagy. One of the triggers for mitochondrial-mediated apoptosis is the production of reactive oxygen species (ROS), which include hydrogen peroxide, superoxide, hydroxyl radical, nitric oxide, and peroxynitrite. Recently, several studies have indicated that ROS may also be involved in the induction of autophagy. In the present study, we used H2O2 to induce mitochondrial stress and examined apoptotic- and autophagic-related gene expression and observed LC3 protein (autophagosome presence marker) expression in porcine parthenotes developing in vitro. In porcine four-cell parthenotes cultured for 5 days in NCSU37 medium containing 0.4% BSA, the developmental rate and mitochondrial distribution did not differ from that of the group supplemented with 100 μM H2O2 but significantly decreased in the group supplemented with 500 μM H2O2 (P<0.05). Transmission electron microscopy (TEM) indicated that whereas normal shaped mitochondria were observed in blastocysts from the control group, abnormal mitochondria (mitophagy) and autophagic vacuoles were observed in blastocysts from the group that received 500 μM H2O2. Furthermore, addition of H2O2 (100 μM and 500 μM) decreased cell numbers (P<0.05) and increased both apoptosis (P<0.05) and LC3 protein expression in the blastocysts. Real time RT-PCR showed that H2O2 significantly decreased mRNA expression of anti-apoptotic gene Bcl-xL but increased pro-apoptotic genes, Caspase 3 (Casp3) and Bak, and autophagy-related genes, microtubule-associated protein 1 light chain 3 (Map1lc3b) and lysosomal-associated membrane protein 2 (Lamp2). However, the addition of H2O2 had no effect on mRNA expression levels in nuclear DNA-encoded mitochondrial-related genes, cytochrome oxidase (Cox) 5a, Cox5b, and Cox6b1, but decreased mitochondrial DNA-encoded genes, D-loop (Dloop) and cytochrome b (Cytb), in blastocysts. These results suggest that H2O2 leads to mitochondrial dysfunction that results in apoptosis and autophagy, which is possibly related to porcine early embryo development.

Spc25 is a component of the Ndc80 complex which consists of Ndc80, Nuf2, Spc24, and Spc25. Previous work has shown that Spc25 is involved in regulation of kinetochore microtubule attachment, localization of Ndc80, and the spindle assembly checkpoint in mitosis. The role of Spc25 in meiosis remains unknown. Here, we report its expression, localization and functions in mouse oocyte meiosis. The Spc25 mRNA level gradually increased from the GV to MI stage, but decreased by MII during mouse oocyte meiotic maturation. Immunofluorescent staining showed that Spc25 was restricted to the germinal vesicle, and associated with chromosomes during all stages after GVBD. Overexpression of Spc25 resulted in oocyte meiotic arrest, chromosome misalignment and spindle disruption. Conversely, Spc25 RNAi resulted in precocious polar body extrusion and caused severe chromosome misalignment and aberrant spindle formation. Spc25 RNAi affected Ndc80 localization, but Ndc80 RNAi did not affect Spc25 localization.Survivin MO caused Ndc80 dispersion but did not affect localization of Spc25. Our data suggest that Spc25 is required for chromosome alignment, spindle formation, and spindle checkpoint activity through the regulation of Ndc80, but that Spc25 function is independent of survivin during meiosis.

수정에 의한 배 발생은 정자가 난자 내로 침입하여 정자와 난자의 반수체 핵질이 융합되고 이어 유사분열로 이어지는 과정에서 시작된다. 하지만 수정 및 초기 배 발생 동안 자웅 핵질과 난 세포질 구성 요소 상호간의 작용기전에 관해서는 명확히 알려져 있지 않은 부분이 많다. 수정보조기법인 세포질 내 정자 직접 주입법의 개발은 남성불임치료에 혁신적인 기술로 자리잡고 있을 뿐만 아니라 포유동물의 수정과정을 이해하는데 많은 도움을 주고 있다. 핵치환에 의한 복제동