[Show abstract][Hide abstract] ABSTRACT: Recently, reprogramming of somatic cells from a differentiated to pluripotent state by overexpression of specific external transcription factors has been accomplished. It has been widely speculated that an undifferentiated state may make donor cells more efficient for nuclear transfer. To test this hypothesis, we derived induced pluripotent stem cells (iPS cells) from several somatic cell lines: mouse embryonic fibroblast (MEF), adult tail tip fibroblast (TTF), and brain neural stem cells (NSCs). Three dimensional (3D)-fluorescent in situ hybridization (FISH) and quantitative-FISH (Q-FISH) were then used to evaluate constitutive (pericentric and telomeric) heterochromatin organization in these iPS cells and in their parental differentiated cells. Here, we show that important nuclear remodeling and telomeres rejuvenation occur in these iPS cells regardless of their parental origin. When we used these cells as donors for nuclear transfer, we produced live-born cloned mice at much higher rates with the iPS-induced cells than with the parental cell lines. Interestingly, we noticed that developmental potential after nuclear transfer could be correlated with telomere length of the donor cells. Altogether, our findings suggest that constitutive heterochromatin organization from differentiated somatic cells can be reprogrammed to the pluripotent state by induction of iPS cells, which in turn support nuclear transfer procedure quite efficiently.
Stem cells and development 06/2012; 21(16):3001-9. · 4.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several research groups have suggested that the embryonic-abembryonic (Em-Ab) axis in the mouse can be predicted by the first cleavage plane of the early embryo. Currently, it is not known whether this early patterning occurs in cloned embryos produced by nuclear transfer and whether it affects development to term. In this work, the relationship between the first cleavage plane and the Em-Ab axis was determined by the labeling of one blastomere in cloned mouse embryos at the 2-cell stage, followed by ex-vivo tracking until the blastocyst stage. The results demonstrate that approximately half of the cloned blastocysts had an Em-Ab axis perpendicular to the initial cleavage plane of the 2-cell stage. These embryos were classified as "orthogonal" and the remainder as "deviant". Additionally, we report here that cloned embryos were significantly more often orthogonal than their naturally fertilized counterparts and overexpressed Sox2. Orthogonal cloned embryos demonstrated a higher rate of post-implantation embryonic development than deviant embryos, but cloned pups did not all survive. These results reveal that the angular relationship between the Em-Ab axis and the first cleavage plane can influence later development and they support the hypothesis that proper early patterning of mammalian embryos is required after nuclear transfer.
[Show abstract][Hide abstract] ABSTRACT: Somatic cell nuclear transfer (SCNT) has been successfully used in many species to produce live cloned offspring, albeit with low efficiency. The low frequency of successful development has usually been ascribed to incomplete or inappropriate reprogramming of the transferred nuclear genome. Elucidating the genetic differences between normal fertilized and cloned embryos is key to understand the low efficiency of SCNT. Here, we show that expression of HSPC117, which encodes a hypothetical protein of unknown function, was absent or very low in cloned mouse blastocysts. To investigate the role of HSPC117 in embryo development, we knocked-down this gene in normal fertilized embryos using RNA interference. We assessed the post-implantation survival of HSPC117 knock-down embryos at 3 stages: E9 (prior to placenta formation); E12 (after the placenta was fully functional) and E19 (post-natal). Our results show that, although siRNA-treated in vivo fertilized/produced (IVP) embryos could develop to the blastocyst stage and implanted without any difference from control embryos, the knock-down embryos showed substantial fetal death, accompanied by placental blood clotting, at E12. Furthermore, comparison of HSPC117 expression in placentas of nuclear transfer (NT), intracytoplasmic sperm injection (ICSI) and IVP embryos confirmed that HSPC117 deficiency correlates well with failures in embryo development: all NT embryos with a fetus, as well as IVP and ICSI embryos, had normal placental HSPC117 expression while those NT embryos showing reduced or no expression of HSPC117 failed to form a fetus. In conclusion, we show that HSPC117 is an important gene for post-implantation development of embryos, and that HSPC117 deficiency leads to fetal abnormalities after implantation, especially following placental formation. We suggest that defects in HSPC117 expression may be an important contributing factor to loss of cloned NT embryos in vivo.
Biochemical and Biophysical Research Communications 07/2010; 397(3):407-12. · 2.28 Impact Factor