Gata4 blocks somatic cell reprogramming by directly repressing Nanog.

Somatic cells can be reprogrammed to induced pluripotent stem (iPS) cells by ectopic expression of the four factors Oct4, Klf4, Sox2, and Myc. Here, we investigated the role of Gata4 in the reprogramming process and present evidence for a negative role of this family of transcription factors in the induction of pluripotency. Coexpression of Gata4 with Oct4, Klf4, and Sox2 with or without Myc in mouse embryonic fibroblasts greatly impaired reprogramming and endogenous Nanog expression. The lack of Nanog upregulation was associated with a blockade in the transition from the initiation phase of reprogramming to the full pluripotent state characteristic of iPS cells. Addition of Nanog to the reprogramming cocktail blocked the deleterious effects observed with Gata4 expression. Downregulation of endogenous Gata4 by short hairpin RNAs during reprogramming both accelerated and increased the efficiency of the process and augmented the mRNA levels of endogenous Nanog. Using comparative genomics, we identified a consensus binding site for Gata factors in an evolutionary conserved region located 9 kb upstream of the Nanog gene. Using chromatin immunoprecipitation, gel retardation, and luciferase assays, we found that Gata4 bound to this region and inhibited Nanog transcription in mouse embryonic stem cells. Overall, our results describe for first time the negative effect of Gata4 in the reprogramming of somatic cells and highlight the role of Gata factors in the transcriptional networks that control cell lineage choices in the early embryo.

[Pregnancy outcome and the status of the newborn infant after ICSI at La Conception Hospital in Marseille]. / Evolution des grossesses et état des enfants à la naissance après ICSI à l'hôpital de La Conception à Marseille.

OBJECTIVE: To evaluate obstetric outcome of pregnancies and pediatric follow-up of children born after ICSI procedure. MATERIAL AND METHOD: Prospective study from october 1994 to September 1998 in medical assisted procreations center in La Conception hospital in Marseilles. Three hundred forty-two couples undergoing ICSI procedures. INTERVENTIONS: analysis of pregnancy rates, prematurity rates, obstetric outcome and frequency of congenital malformations. RESULTS: One hundred seventy-eight pregnancies have been obtained with 111 children. Multiple pregnancy rate arise 29.7%. The average term at birth in the singleton pregnancies (38.7 weeks) is higher than in the twins (35.7 weeks). The prematurity rate of delivery before 35 weeks of gestation is about 9.6%. Seven of 111 neonates was born with a congenital malformation, no cardiovascular one. One of boys presents a bilateral cryptorchidism with severe bilateral hypotrophy. CONCLUSIONS: Our results are similar with those of others teams. Congenital malformation rates is near rates reported in others studies. However, no bilateral cryptorchidism with bilateral severe hypotrophy has been yet reported in literature.

[Morphological aspect of embryos obtained after fertilization in vitro for male factor or ICSI]. / Aspect morphologique des embryons obtenus après une fécondation in vitro pour indication masculine ou ICSI.

OBJECTIVE: In order to study the eventual impact on fertilization and embryo characteristics of the microinjection procedure we compared the quality of the embryos obtained by ICSI with those of in vitro fertilization with male factors (MF IVF). MATERIAL AND METHODS: One hundred thirty-four cycles of IVF treatment (group 1) were selected with oligoasthenozoospermia according to WHO criteria with a total number of motile spermatozoa between 500,000 and 1 million. One thousand eighty-eight mature oocytes and 486 embryos were obtained. One hundred forty-three cycles of intracytoplasmic sperm injection (group 2) were performed in couples whose in vitro fertilization was imparticable because of extreme sperm impairment. One thousand one hundred forty-seven mature oocytes were injected and 626 embryos were obtained. RESULTS: In group 1, the pregnancy rate per embryo transfer and the implantation rate were respectively 22.7% and 12.3%. In group 2, the pregnancy rate per embryo transfer was 37.1% and the implantation rate was 17%. The statistical analysis of the embryos obtained in the two different groups did not demonstrate any difference in the distribution of the more regular and less fragmented embryos (group A) and those of the more irregular and fragmented embryos (group B). No statistical difference was demonstrated in the chronology of the division of these embryos (groups 1 and 2). CONCLUSION: The pregnancy rate by cycle and by transfer reported by ICSI (p < 0.003 and p < 0.015 respectively) could be related to a significantly higher mean number of transferred embryos (2.65 vs 2.02) in probable relation with a higher cleavage rate (p < 0.00001).

[Quality of embryos in unexplained sterility]. / Qualité des embryons dans les stérilités inexpliquées.

In our study, the rate of pregnancy by transfer and puncture was not significantly different in unexplained and in tubal infertility, but the mean number of transferred embryos was significantly higher in the first group. To explain these data, we compared the quality of embryos in 32 punctures realized among 29 women with unexplained infertility and in 171 punctures planned among 156 women with tubal infertility. The percentage of embryos with 4 or more blastomeres was significantly lower in the unexplained infertility group than in the pure tubal infertility group.

[Intraperitoneal insemination]. / Inséminations intrapéritonéales.

Intra-perineal insemination is a technique used in assisted reproduction. The principle is to stimulate the ovaries, to obtain the partner's sperm and to prepare it by similar techniques to those used in in-vitro fertilization so that the sperm can be placed near the ovaries in the Pouch of Douglas by a direct puncture of the posterior vaginal fornix without using anaesthesia. The woman's pelvis has to be absolutely normal. This technique is useful in cases of unexplained sterility, cervical sterility and inadequate sperm function.