Nobuhiro Suzumori

Nobox is a homeobox-encoding gene preferentially expressed in primordial and growing oocytes

To identify novel genes involved in early mammalian folliculogenesis, we used the Unigene collection of mouse cDNA libraries to identify unique expressed sequence tags in a newborn mouse ovary cDNA library. Nobox (newborn ovary homeobox-encoding gene) was one of several genes identified by in silico (electronic database) subtraction. We cloned the mouse Nobox cDNA and characterized its genomic organization. The gene spans 14kb and is encoded by eight exons. The Nobox gene maps to proximal chromosome 6 in the mouse, and we identified a portion of the human gene encoding a NOBOX homolog which resides at a syntenic position on chromosome 7q35. Reverse transcriptase polymerase chain reaction and Northern blot analyses show that Nobox is preferentially expressed in the ovary at high levels. In situ hybridization analysis demonstrates that Nobox mRNA is present in primordial and growing oocytes. Nobox is one of the first homeobox-encoding genes preferentially expressed during mammalian folliculogenesis.

Abnormal embryonic karyotype is the most frequent cause of recurrent miscarriage

BACKGROUND We previously found that a normal karyotype in a previous miscarriage is a predictor of subsequent miscarriage. However, the prevalence of recurrent miscarriage caused by an abnormal embryonic karyotype has not yet been reported, since embryonic karyotype is not typically analyzed during conventional examinations. METHODS A total of 482 patients who underwent both embryonic karyotype determination and conventional examinations for recurrent miscarriage were enrolled in this study. The distribution of the causes and the live birth rate for each cause were examined. RESULTS The total percentage of subjects in whom conventional causes of recurrent miscarriage could be detected was 29.5%. The prevalence of the abnormal embryonic karyotype was 41.1% in the subjects in whom no conventional causes of miscarriage could be identified. The prevalence of recurrent miscarriage of truly unexplained cause, that is, of subjects without conventional causes in whom the embryonic karyotype was ascertained to be normal, was 24.5%. Among the patients in whom the first determination revealed an abnormal embryonic karyotype, 76.2% (32/42) showed an abnormal embryonic karyotype in the repeat determination as well. The cumulative live birth rate (71.9%) in women with recurrent miscarriages caused by the abnormal embryonic karyotype was significantly higher than that (44.7%) in women with recurrent miscarriages associated with the embryonal euploidy. CONCLUSION An abnormal embryonic karyotype was found to represent the commonest cause of recurrent miscarriage, and the percentage of cases with recurrent miscarriage of truly unexplained cause was limited to 24.5%.The two groups should be distinguished for both clinical and research purposes.

RFPL4 interacts with oocyte proteins of the ubiquitin-proteasome degradation pathway.

Oocyte meiosis and early mitotic divisions in developing embryos rely on the timely production of cell cycle regulators and their clearance via proteasomal degradation. Ret Finger Protein-Like 4 (Rfpl4), encoding a RING finger-like protein with a B30.2 domain, was discovered during an in silico search for germ cell-specific genes. To study the expression and functions of RFPL4 protein, we performed immunolocalizations and used yeast two-hybrid and other protein–protein interaction assays. Immunohistochemistry and immunofluorescence showed that RFPL4 accumulates in all growing oocytes and quickly disappears during early embryonic cleavage. We used a yeast two-hybrid model to demonstrate that RFPL4 interacts with the E2 ubiquitin-conjugating enzyme HR6A, proteasome subunit β type 1, ubiquitin B, as well as a degradation target protein, cyclin B1. Coimmunoprecipitation analyses of in vitro translated proteins and extracts of transiently cotransfected Chinese hamster ovary (CHO)-K1 cells confirmed these findings. We conclude that, like many RING-finger containing proteins, RFPL4 is an E3 ubiquitin ligase. The specificity of its expression and these interactions suggest that RFPL4 targets cyclin B1 for proteasomal degradation, a key aspect of oocyte cell cycle control during meiosis and the crucial oocyte-to-embryo transition to mitosis.

Genetic Factors as a Cause of Miscarriage

Aneuploidy in the conceptus or fetus, occurs in 5-10% of all pregnancies and is a common reproductive problem in humans. Most aneuploid conceptuses die in utero, resulting in early pregnancy loss. Causes of recurrent miscarriage may include abnormal chromosomes in either partner, particularly translocations, antiphospholipid antibodies and uterine anomalies. Chromosomal aberrations in parents are a major pre-disposing factor and causative of abortion if carried over to the embryo. The transmission rate in the embryo can be speculated to be about 50%. Embryo morphology, developmental rates, and maternal age are correlated with chromosomal abnormalities. Translocation in either partner is one of the most important causes of recurrent miscarriage and the prognosis of subsequent pregnancy in couples with abnormal embryonic karyotype is poorer than that in couples with normal chromosome karyotypes. As for parents whose karyotypes are normal, the frequency of normal embryonic karyotypes significantly increases with the number of previous abortions and a normal karyotype in a previous pregnancy is a predictor of subsequent miscarriage. Recently, many kinds of genetic polymorphisms have also been found to be associated with recurrent miscarriages. In contrast, preimplantation genetic diagnosis for aneuploidy screening is sometimes performed in patients with unexplained recurrent miscarriages. We review genetic factors as a cause of miscarriage.

No association of C677T methylenetetrahydrofolate reductase and an endothelial nitric oxide synthase polymorphism with recurrent pregnancy loss

Problem:  It is controversial whether polymorphisms of methylenetetrahydrofolate reductase (MTHFR) and the endothelial nitric oxide synthase (eNOS) are associated with recurrent pregnancy loss.

Candidate Genes for Premature Ovarian Failure

Premature ovarian failure (POF) is defined as the cessation of ovarian function under the age of 40 years and is characterized by amenorrhea, hypoestrogenism, and elevated serum gonadotropin concentrations. POF affects 1% of all women and occurs in approximately 0.1% before the age of 30 years. To date, mutations associated with POF have been identified in a small number of genes, including those encoding inhibin alpha (INHA), the FSH receptor and the LH/chorio gonadotrophin receptor. Germ cell specific genes such as Gdf9, Bmp15, and Rfpl4 may also play important roles in human oogenesis. Transcription factors that regulate oocyte gene expression in animal models and include Nobox, Taf4b, Figla, Lhx8, Sohlh1 and Sohlh2 are likely to be key mediators of fertility in humans. In this review, after summarizing the general background on human POF, we focus on insights gained from the animal models with regards to mammalian folliculogenesis. Studies in animal models provide new candidate genes for ovarian failure in humans.

Uterine anomaly and recurrent pregnancy loss.

Women with recurrent pregnancy loss have a 3.2 to 6.9% likelihood of having a major uterine anomaly and a 1.0 to 16.9% chance of having an arcuate uterus. Bicornuate and septate uterine have a negative impact on reproductive outcomes and are associated with subsequent euploid miscarriage. The impact of an arcuate uterus on pregnancy outcome remains unclear. There are no definitive criteria to distinguish among the arcuate, septate, and bicornuate uteri. The American Fertility Society classification of Müllerian anomalies is the most common standardized classification of uterine anomalies. According to estimates, 65 to 85% of patients with bicornuate or septate uteri have a successful pregnancy outcome after metroplasty. However, 59.5% of the patients with such anomalies have a successful subsequent pregnancy without surgery, with a cumulative live birthrate of 78.0%. There is no case-control study to compare live birthrates in women who had surgery compared with those who did not. Strict criteria to distinguish between the bicornuate and septate uterus should be established. Further study is needed to confirm the benefits of metroplasty.

Peripheral natural killer cell activity as a predictor of recurrent pregnancy loss: a large cohort study.

OBJECTIVE To determine the predictive value of preconceptional peripheral blood natural killer (pNK) cell activity in patients with recurrent pregnancy loss (RPL). DESIGN Cohort study. SETTING University department. PATIENT(S) A total of 552 patients with a history of two to six consecutive miscarriages. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) The predictive value of preconceptional pNK cell activity for subsequent miscarriage was analyzed using multivariable logistic regression analysis, with age, number of previous miscarriages, and presence/absence of previous live births and bed rest as covariates. RESULT(S) Age and number of previous miscarriages, but not high pNK cell activity, were found to be independent risk factors for a subsequent miscarriage. No effect of bed rest and previous live birth on the likelihood of live birth was observed (odds ratios 1.28 [95% confidence interval 0.81-2.02] and 0.91 [0.52-1.59], respectively). CONCLUSION(S) Elevated pNK cell activity was found to not be an independent risk factor for subsequent miscarriage. Clinicians should not measure the plasma NK activity as a systematic recurrent pregnancy loss examination, because its clinical significance is yet to be established.

Paternal uniparental disomy 14 and related disorders: Placental gene expression analyses and histological examinations

Although recent studies in patients with paternal uniparental disomy 14 [upd(14)pat] and other conditions affecting the chromosome 14q32.2 imprinted region have successfully identified underlying epigenetic factors involved in the development of upd(14)pat phenotype, several matters, including regulatory mechanism(s) for RTL1 expression, imprinting status of DIO3 and placental histological characteristics, remain to be elucidated. We therefore performed molecular studies using fresh placental samples from two patients with upd(14)pat. We observed that RTL1 expression level was about five times higher in the placental samples of the two patients than in control placental samples, whereas DIO3 expression level was similar between the placental samples of the two patients and the control placental samples. We next performed histological studies using the above fresh placental samples and formalin-fixed and paraffin-embedded placental samples obtained from a patient with a maternally derived microdeletion involving DLK1, the-IG-DMR, the MEG3-DMR and MEG3. Terminal villi were associated with swollen vascular endothelial cells and hypertrophic pericytes, together with narrowed capillary lumens. DLK1, RTL1 and DIO3 proteins were specifically identified in vascular endothelial cells and pericytes, and the degree of protein staining was well correlated with the expression dosage of corresponding genes. These results suggest that RTL1as-encoded microRNA functions as a repressor of RTL1 expression, and argue against DIO3 being a paternally expressed gene. Furthermore, it is inferred that DLK1, DIO3 and, specially, RTL1 proteins, play a pivotal role in the development of vascular endothelial cells and pericytes.

Conservative treatment by angiographic artery embolization of an 11-week cervical pregnancy after a period of heavy bleeding

OBJECTIVE To describe a rare case of conservative treatment of an 11-week cervical pregnancy after a period of heavy bleeding. DESIGN Case report. SETTING A university hospital. PATIENT(S) A 33-year-old woman was admitted to our hospital for treatment of a cervical pregnancy. Two-and-a-half years thereafter, she gave birth to a healthy baby by vaginal delivery at 38 weeks of gestation. INTERVENTION(S) Systemic methotrexate treatment, ligation of descending branches of uterine arteries, cervical cerclage, and unilateral internal iliac artery embolization. MAIN OUTCOME MEASURE(S) Transvaginal ultrasound, magnetic resonance imaging, and arteriography findings. RESULT(S) The patient was successfully treated with unilateral internal iliac artery embolization on the same side as the pregnancy in the 11th gestational week. CONCLUSION(S) After failed methotrexate and vessel ligation in cervical pregnancy, unilateral internal iliac artery embolization is an effective and conservative treatment that allows preservation of reproduction potential.