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Jeong-Woo Kwon, Nam-Hyung Kim and Inchul Choi

Coxsackie virus and adenovirus receptor (CXADR) is a member of the immunoglobulin superfamily as well as a member of the junctional adhesion molecule family of adhesion receptor. In human pre-implantation embryos, CXADR was detected and co-localized with tight junction (TJ) proteins on the membrane of the trophectoderm. However, its physiological roles were not elucidated in terms of blastocyst formation. Here, we reported expression patterns and biological functions of CXADR in porcine pre-implantation embryos. The transcripts of CXADR were detected at all stages of pre-implantation. Particularly, its expression dramatically increased and preferentially localized at the edge of cell–cell contacts, rather than in the nucleus from the eight-cell stage onwards. CXADR expression was knocked down (KD) by microinjecting double-stranded RNA into one-cell parthenotes. The vast majority of CXADR KD embryos failed to develop to the blastocyst stage, and a few developed KD blastocysts did not expand fully. Analysis of adherens junction (AJ)- and TJ-associated genes/proteins using qRT-PCR, immunocytochemistry and assessment of TJ permeability using FITC-dextran uptake assay revealed that the developmental failure and relatively small cavities are attributed to the defects of TJ assembly. In summary, CXADR is necessary for the AJ and TJ assembly/biogenesis during pre-implantation development.

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Xiang-Shun Cui, Yu-Jeong Jeong, Hwa-Young Lee, Sun-Hong Cheon and Nam-Hyung Kim

This study was conducted to determine the effects of polyvinyl alcohol (PVA), fetal bovine serum (FBS) and bovine serum albumin (BSA) on blastocoel formation, total cell number, apoptosis and Bcl-xL and Bak gene expression in porcine presumptive diploid parthenotes developing in vitro. The addition of 0.4% BSA to the culture medium enhanced the development of 2-cell or late 4-cell stage parthenotes to the blastocyst stage (P < 0.01) while FBS decreased the incidence of blastocoel formation. FBS also reduced the frequency of blastocysts developed from both 2-cell (P < 0.001) and late 4-cell (P < 0.05) embryos and increased the percentage of blastocysts undergoing apoptosis (P < 0.001). The relative abundance of Bcl-xL mRNA in presumptive diploid parthenotes in the control, PVA- and BSA-supplemented medium was similar to that of in vivo-derived embryos, but was significantly higher than in parthenotes cultured with FBS supplement (P < 0.05). Bak mRNA significantly increased at the blastocyst stage in FBS-supplemented cells (P < 0.01). These results suggest that apoptosis-related gene expression is significantly affected by FBS, and that this may result in alteration of apoptosis and embryo viability of porcine embryos developing in vitro.

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Zhe-Long Jin, Xing-Hui Shen, Liang Shuang, Jeong-woo Kwon, Min-Jeong Seong and Nam-Hyung Kim

Homologous recombination (HR) plays a critical role in facilitating replication fork progression when the polymerase complex encounters a blocking DNA lesion, and it also serves as the primary mechanism for error-free DNA repair of double-stranded breaks. DNA repair protein RAD51 homolog 1 (RAD51) plays a central role in HR. However, the role of RAD51 during porcine early embryo development is unknown. In the present study, we examined whether RAD51 is involved in the regulation of early embryonic development of porcine parthenotes. We found that inhibition of RAD51 delayed cleavage and ceased development before the blastocyst stage. Disrupting RAD51 activity with RNAi or an inhibitor induces sustained DNA damage, as demonstrated by the formation of distinct γH2AX foci in nuclei of four-cell embryos. Inhibiting RAD51 triggers a DNA damage checkpoint by activating the ataxia telangiectasia mutated (ATM)–p53–p21 pathway. Furthermore, RAD51 inhibition caused apoptosis, reactive oxygen species accumulation, abnormal mitochondrial distribution and decreased pluripotent gene expression in blastocysts. Thus, our results indicate that RAD51 is required for proper porcine parthenogenetic activation (PA) embryo development.

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Na-Ra Han, Chan-Lee Park, Na-Rae Kim, Hee-Yun Kim, Myoung-Schook Yoou, Sun-Young Nam, Phil-Dong Moon, Hyun-Ja Jeong and Hyung-Min Kim

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Na-Ra Han, Chan-Lee Park, Na-Rae Kim, Hee-Yun Kim, Myoung-Schook Yoou, Sun-Young Nam, Phil-Dong Moon, Hyun-Ja Jeong and Hyung-Min Kim

Menopause is a significant physiological phase that occurs as women's ovaries stop producing ovum and the production of estrogen declines. Human placenta and some amino acids are known to improve menopausal symptoms. In this study, we investigated that porcine placenta extract (PPE) and arginine (Arg), a main amino acid of PPE, would have estrogenic activities in ovariectomized (OVX) mice as a menopause mouse model, human breast cancer cell line (MCF-7) cells, and human osteoblast cell line (MG-63) cells. PPE or Arg significantly inhibited the body weight and increased the vagina weight compared to the OVX mice. PPE or Arg ameliorated the vaginal atrophy in the OVX mice. The levels of 17β-estradiol and the activities of alkaline phosphatase (ALP) were significantly increased by PPE or Arg in the serum of OVX mice. Trabecular bone parameters such as bone mineral density and porosity were also improved by PPE or Arg in the OVX mice. In the MCF-7 and MG-63 cells, PPE or Arg significantly increased the cell proliferation, estrogen receptor β mRNA expression, and estrogen-response elements luciferase activity. Finally, PPE or Arg increased the activations of ALP and extracellular signal-regulated kinase 1/2 in the MG-63 cells. These results indicate that PPE or Arg would have estrogenic and osteoblastic activity. Therefore, PPE or Arg may be useful as new pharmacological tools for treating menopausal symptoms including osteoporosis.

Free Korean abstract: A Korean translation of this abstract is freely available at http://www.reproduction-online.org/content/150/3/173/suppl/DC1.