Signal transducers and activators of transcription-3 (Stat3) plays a central role in interleukin-6 (IL-6)-mediated cell proliferation by inhibiting apoptosis in a variety of cell types. MicroRNA-21 (miRNA-21), a ubiquitous miRNA, acts as an anti-apoptotic factor that seems to be indirectly but strictly linked to Stat3. In order to determine whether the IL-6 induced Stat3 anti-apoptosis pathway is linked with miRNA-21, we first determined the effects of recombinant mouse IL-6 on Stat3 expression, mouse embryo viability, and the mRNA levels of apoptosis related genes and miRNA-21 during mouse embryo development in vitro. Addition of 10 or 100 ng/ml of recombinant IL-6 to the culture medium did not affect the developmental ability of 2-cell stage embryos into blastocysts. However, total cell number was significantly increased and apoptosis was reduced in blastocyst stage embryos cultured in the presence of 100 ng/ml of recombinant IL-6. Furthermore, addition of recombinant IL-6 to the culture medium significantly increased the copy numbers of anti-apoptotic miRNA-21, up-regulated Bcl2l1, and down-regulated casp3. Similarly, the injection of mature miRNA-21 into cells up-regulated Bcl2l1 and down-regulated casp3. These results suggest that the induction of the Stat3 anti-apoptotic pathway by IL-6 is linked to miRNA-21 expression, which possibly results in the regulation of cell apoptosis in early mouse embryo development.

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Abstract. The effects of two antioxidants, superoxide dismutase (SOD) and the flavonoid 3,4-dihydroxyflavone (DHF), on bovine embryo development in vitro were examined. Blastocyst development, total cell and inner cell mass (ICM) numbers, intracellular levels of reactive oxygen species (ROS), apoptotic indices and gene expression levels were examined before and after treatment of day 2 bovine embryos (≥2-4 cells) with various concentrations of 3,4-DHF or SOD for 6 days. Statistical analysis was performed using analysis of variance, with significance defined at the P<0.05 level. SOD had no significant effect on bovine embryo development at any tested concentration (control, 32.8%; 300 U/ ml, 33.9%; 600 U/ml, 24.2%). In contrast, 10 μM 3,4-DHF promoted higher blastocyst development (39.3%) than any other concentration (control, 26.7%; 1 μM, 30.3%; 50 μM, 29.5%; 100 μM, 20.5%). Compared with 300 U/ml SOD, 10 μM 3,4-DHF resulted in significantly higher blastocyst development (44.2%) (control, 31.5%; SOD 300 U/ml, 33.6%). Treatment with 3,4-DHF increased the ICM cell number and reduced intracellular ROS production and apoptotic cell numbers. When O2 tension was decreased from 20% (high tension) to 5% (low tension), embryo development rates were doubled regardless of 3,4-DHF treatment. Under high O2 tension, 10 μM 3,4-DHF treatment may render bovine embryo development similar to a low O2 tension environment. The best blastocyst development was obtained under low O2 tension plus 10 μM 3,4-DHF treatment. The relative expression levels of antioxidant (MnSOD), antiapoptotic (Survivin, Bax inhibitor) and growth-related genes (IFN-τ, Glut-5) were significantly increased after 3,4-DHF treatment, while the expression levels of oxidant (Sox) and apoptotic genes (Caspase-3 and Bax) were reduced. These results suggest that 3,4-DHF may promote the in vitro development of bovine embryos through its antioxidant and antiapoptotic effects.

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Induced pluripotent stem (iPS) cells are a new alternative for the development of patient-specific stem cells, and the aim of this study was to determine whether differences exist between the cellular and molecular profiles of iPS cells, generated using lentiviral vectors, compared to ES cells. The lentiviral infection efficiency differed according to the method of cell culture (adherent cells: 0.085%; suspended cells: 0.785%). Six iPS cell lines exhibited typical ES cell morphology and marker expression, but varied in their in vitro/in vivo differentiation ability. Global gene transcription analysis revealed that core pluripotency genes were expressed at lower levels in iPS cell lines compared to D3-ES cells (Pou5f1: Â1.6*2.2-fold, Sox2: Â2.58*10.0-fold, Eras: Â1.08*2.54-fold, Dppa5a: Â1.04*1.41-fold), while other genes showed higher expression in iPS cells (Lin28: Â1.43*2.33-fold; Dnmt3b: Â1.33*2.64-fold). This pattern was repeated in a survey of specific functional groups of genes (surface markers, cell death, JAK-STAT and P13K-AKT signaling pathways, endothelial, cardiovascular, and neurogenesis genes). Among the iPS cell lines examined, only two showed similar characteristics to ES cells. These results demonstrated that, in addition to cellular characterization, the numerical evaluation of gene expression using DNA microarrays might help to identify the stem cell stability and pluripotency of iPS cells.

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