OBOX regulates mouse zygotic genome activation and early development.

Zygotic genome activation (ZGA) activates the quiescent genome to enable the maternal-to-zygotic transition1,2. However, the identity of transcription factors that underlie mammalian ZGA in vivo remains elusive. Here we show that OBOX, a PRD-like homeobox domain transcription factor family (OBOX1-OBOX8)3-5, are key regulators of mouse ZGA. Mice deficient for maternally transcribed Obox1/2/5/7 and zygotically expressed Obox3/4 had a two-cell to four-cell arrest, accompanied by impaired ZGA. The Obox knockout defects could be rescued by restoring either maternal and zygotic OBOX, which suggests that maternal and zygotic OBOX redundantly support embryonic development. Chromatin-binding analysis showed that Obox knockout preferentially affected OBOX-binding targets. Mechanistically, OBOX facilitated the 'preconfiguration' of RNA polymerase II, as the polymerase relocated from the initial one-cell binding targets to ZGA gene promoters and distal enhancers. Impaired polymerase II preconfiguration in Obox mutants was accompanied by defective ZGA and chromatin accessibility transition, as well as aberrant activation of one-cell polymerase II targets. Finally, ectopic expression of OBOX activated ZGA genes and MERVL repeats in mouse embryonic stem cells. These data thus demonstrate that OBOX regulates mouse ZGA and early embryogenesis.

Polycomb Group Proteins Regulate Chromatin Architecture in Mouse Oocytes and Early Embryos.

In mammals, chromatin organization undergoes drastic reorganization during oocyte development. However, the dynamics of three-dimensional chromatin structure in this process is poorly characterized. Using low-input Hi-C (genome-wide chromatin conformation capture), we found that a unique chromatin organization gradually appears during mouse oocyte growth. Oocytes at late stages show self-interacting, cohesin-independent compartmental domains marked by H3K27me3, therefore termed Polycomb-associating domains (PADs). PADs and inter-PAD (iPAD) regions form compartment-like structures with strong inter-domain interactions among nearby PADs. PADs disassemble upon meiotic resumption from diplotene arrest but briefly reappear on the maternal genome after fertilization. Upon maternal depletion of Eed, PADs are largely intact in oocytes, but their reestablishment after fertilization is compromised. By contrast, depletion of Polycomb repressive complex 1 (PRC1) proteins attenuates PADs in oocytes, which is associated with substantial gene de-repression in PADs. These data reveal a critical role of Polycomb in regulating chromatin architecture during mammalian oocyte growth and early development.

The landscape of RNA Pol II binding reveals a stepwise transition during ZGA.

Zygotic genome activation (ZGA) is the first transcription event in life1. However, it is unclear how RNA polymerase is engaged in initiating ZGA in mammals. Here, by developing small-scale Tn5-assisted chromatin cleavage with sequencing (Stacc-seq), we investigated the landscapes of RNA polymerase II (Pol II) binding in mouse embryos. We found that Pol II undergoes 'loading', 'pre-configuration', and 'production' during the transition from minor ZGA to major ZGA. After fertilization, Pol II is preferentially loaded to CG-rich promoters and accessible distal regions in one-cell embryos (loading), in part shaped by the inherited parental epigenome. Pol II then initiates relocation to future gene targets before genome activation (pre-configuration), where it later engages in full transcription elongation upon major ZGA (production). Pol II also maintains low poising at inactive promoters after major ZGA until the blastocyst stage, coinciding with the loss of promoter epigenetic silencing factors. Notably, inhibition of minor ZGA impairs the Pol II pre-configuration and embryonic development, accompanied by aberrant retention of Pol II and ectopic expression of one-cell targets upon major ZGA. Hence, stepwise transition of Pol II occurs when mammalian life begins, and minor ZGA has a key role in the pre-configuration of transcription machinery and chromatin for genome activation.

Pregnancy and obstetric outcomes of dichorionic triamniotic triplet pregnancies with selective foetal reduction after assisted reproductive technology.

BACKGROUND: It is generally beneficial and recommended that dichorionic triamniotic (DCTA) triplet pregnancies be reduced to monochorionic (MC) twin or singleton pregnancies after assisted reproductive technology (ART). However, some infertile couples still have a firm desire to retain twins. For this reason, the best foetal reduction strategies need to be available for infertile couples and clinicians. Given that data on the elective reduction of DCTA triplet pregnancies to twin pregnancies are scarce, we investigated the outcomes of elective reduction of DCTA triplet pregnancies through the retrospective analysis of previous data. METHOD: Patients with DCTA triplet pregnancies who underwent elective foetal reduction between January 2012 and June 2020 were recruited. A total of 67 eligible patients with DCTA triplet pregnancies were divided into two groups: a DCTA-to-dichorionic diamniotic (DCDA) twin group (n = 38) and a DCTA-to-monochorionic diamniotic (MCDA) twin group (n = 29); the basic clinical data of the two groups were collected for comparison. RESULTS: Compared with the DCDA-to-MCDA twin group, the DCTA-to-DCDA twin group had lower rates of complete miscarriage (7.89% versus 31.03%, p = 0.014), early complete miscarriage (5.26% versus 24.14%, p = 0.034), late preterm birth (25.71% versus 65.00%, p = 0.009) and very low birth weight (0 versus 11.11%, p = 0.025). In addition, the DCTA-to-DCDA twin group had higher rates of full-term delivery (65.71% versus 25.00%, p = 0.005), survival (92.11% versus 68.97%, p = 0.023), and taking the babies home (92.11% versus 68.97%, p = 0.023) than did the DCTA-to-MCDA twin group. In terms of neonatal outcomes, a significantly greater gestational age (38.06 ± 2.39 versus 36.28 ± 2.30, p = 0.009), average birth weight (3020.77 ± 497.33 versus 2401.39 ± 570.48, p < 0.001), weight of twins (2746.47 ± 339.64 versus 2251.56 ± 391.26, p < 0.001), weight of the larger neonate (2832.94 ± 320.58 versus 2376.25 ± 349.95, p < 0.001) and weight of the smaller neonate (2660.00 ± 345.34 versus 2126.88 ± 400.93, p < 0.001) was observed in the DCTA-to-DCDA twin group compared to the DCTA-to-MCDA twin group. CONCLUSION: The DCTA-to-DCDA twin group had better pregnancy and neonatal outcomes than the DCTA-to-MCDA twin group. This reduction approach may be beneficial for patients with dichorionic triamniotic triplet pregnancies who have a strong desire to have DCDA twins.

Resetting Epigenetic Memory by Reprogramming of Histone Modifications in Mammals.

Polycomb group proteins and the related histone modification H3K27me3 can maintain the silencing of key developmental regulators and provide cellular memory. However, how such an epigenetic state is reprogrammed and inherited between generations is poorly understood. Using an ultra-sensitive approach, STAR ChIP-seq, we investigated H3K27me3 across 14 developmental stages along mouse gametogenesis and early development. Interestingly, highly pervasive H3K27me3 is found in regions depleted of transcription and DNA methylation in oocytes. Unexpectedly, we observed extensive loss of promoter H3K27me3 at Hox and other developmental genes upon fertilization. This is accompanied by global erasure of sperm H3K27me3 but inheritance of distal H3K27me3 from oocytes. The resulting allele-specific H3K27me3 patterns persist to blastocysts before being converted to canonical forms in postimplantation embryos, where both H3K4me3/H3K27me3 bivalent promoter marks are restored at developmental genes. Together, these data revealed widespread resetting of epigenetic memory and striking plasticity of epigenome during gametogenesis and early development.

Pregnancy outcomes of monochorionic diamniotic and dichorionic diamniotic twin pregnancies conceived by assisted reproductive technology and conceived naturally: a study based on chorionic comparison.

OBJECTIVE: To evaluate monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin pregnancies conceived by assisted reproductive technology (ART) and conceived naturally. METHODS: We retrospectively analyzed the data on twin pregnancies conceived by ART from January 2015 to January 2022,and compared pregnancy outcomes of MCDA and DCDA twins conceived by ART with those of MCDA and DCDA twins conceived naturally, pregnancy outcomes between MCDA and DCDA twins conceived by ART, and pregnancy outcomes of DCT and TCT pregnancies reduced to DCDA pregnancies with those of DCDA pregnancies conceived naturally. RESULT: MCDA pregnancies conceived by ART accounted for 4.21% of the total pregnancies conceived by ART and 43.81% of the total MCDA pregnancies. DCDA pregnancies conceived by ART accounted for 95.79% of the total pregnancies conceived by ART and 93.26% of the total DCDA pregnancies. Women with MCDA pregnancies conceived by ART had a higher premature delivery rate, lower neonatal weights, a higher placenta previa rate, and a lower twin survival rate than those with MCDA pregnancies conceived naturally (all p < 0.05). Women with DCDA pregnancies conceived naturally had lower rates of preterm birth, higher neonatal weights, and higher twin survival rates than women with DCDA pregnancies conceived by ART and those with DCT and TCT pregnancies reduced to DCDA pregnancies (all p < 0.05). CONCLUSION: Our study confirms that the pregnancy outcomes of MCDA pregnancies conceived by ART are worse than those of MCDA pregnancies conceived naturally. Similarly, the pregnancy outcomes of naturally-conceived DCDA pregnancies are better than those of DCDA pregnancies conceived by ART and DCT and TCT pregnancies reduced to DCDA pregnancies.

Allelic reprogramming of the histone modification H3K4me3 in early mammalian development.

Histone modifications are fundamental epigenetic regulators that control many crucial cellular processes. However, whether these marks can be passed on from mammalian gametes to the next generation is a long-standing question that remains unanswered. Here, by developing a highly sensitive approach, STAR ChIP-seq, we provide a panoramic view of the landscape of H3K4me3, a histone hallmark for transcription initiation, from developing gametes to post-implantation embryos. We find that upon fertilization, extensive reprogramming occurs on the paternal genome, as H3K4me3 peaks are depleted in zygotes but are readily observed after major zygotic genome activation at the late two-cell stage. On the maternal genome, we unexpectedly find a non-canonical form of H3K4me3 (ncH3K4me3) in full-grown and mature oocytes, which exists as broad peaks at promoters and a large number of distal loci. Such broad H3K4me3 peaks are in contrast to the typical sharp H3K4me3 peaks restricted to CpG-rich regions of promoters. Notably, ncH3K4me3 in oocytes overlaps almost exclusively with partially methylated DNA domains. It is then inherited in pre-implantation embryos, before being erased in the late two-cell embryos, when canonical H3K4me3 starts to be established. The removal of ncH3K4me3 requires zygotic transcription but is independent of DNA replication-mediated passive dilution. Finally, downregulation of H3K4me3 in full-grown oocytes by overexpression of the H3K4me3 demethylase KDM5B is associated with defects in genome silencing. Taken together, these data unveil inheritance and highly dynamic reprogramming of the epigenome in early mammalian development.

A homozygous missense mutation in TBPL2 is associated with oocyte maturation arrest and degeneration.

The genetic causes in most of patients with oocyte maturation arrest remain largely unknown. In this study, we identified a homozygous missense mutation (c.895T>C; p.C299R) in TBPL2 (TATA box binding protein like 2) in two infertile sisters with oocyte maturation arrest and degeneration from a consanguineous family by whole-exome sequencing. The TBPL2 mutation is rare and pathogenic, and impaired the transcription initiation function of the protein. Our results showed that TBPL2 mutation might be associated with female infertility due to oocyte maturation arrest and degeneration.

No significant long-term complications from inadvertent exposure to gonadotropin-releasing hormone agonist during early pregnancy in mothers and offspring: a retrospective analysis.

BACKGROUND: Administration of gonadotropin-releasing hormone agonist (GnRH-a) in the luteal phase is commonly used for pituitary suppression during in vitro fertilisation (IVF). There is an ineluctable risk of inadvertent exposure of spontaneous pregnancy to GnRH-a. However, little is known about the pregnancy complications and repregnancy outcomes of the affected women and the neurodevelopmental outcomes of the GnRH-a-exposed children. METHODS: Retrospective analysis was used to determine obstetric and repregnancy outcomes after natural conception in 114 women who naturally conceived while receiving GnRH-a during their early pregnancy over the past 17 years. The GnRH-a-exposed children were evaluated to determine their neonatal characteristics and long-term neurodevelopmental outcomes. The outcomes were compared to those of relevant age-matched control groups. RESULTS: Sixty-five women had 66 live births. The neonatal health outcomes and the incidence of maternal complications were similar in the GnRH-a-exposed and control groups. Thirty-one GnRH-a-exposed children, aged 2-8 years, were available for investigation of neurodevelopment. Except for one case of autism spectrum disorder, the full-scale intelligence quotient score was within the normal range and similar to that of the control group. Most mothers with successful pregnancies and about one-third of the women who had spontaneous abortions were subsequently able to conceive naturally again. IVF is recommended for repregnancy in women who have experienced ectopic pregnancies. CONCLUSIONS: Accidental exposure to GnRH-a in early pregnancy might be safe. Reproductive treatment suggestions for repregnancy should be made with consideration of the outcomes of the previously GnRH-a-exposed spontaneous pregnancy.

Maternal BCAS2 protects genomic integrity in mouse early embryonic development.

Mammalian early embryos maintain accurate genome integrity for proper development within a programmed timeline despite constant assaults on their DNA by replication, DNA demethylation and genetic defects transmitted from germ cells. However, how genome integrity is safeguarded during mammalian early embryonic development remains unclear. BCAS2 (breast carcinoma amplified sequence 2), a core component of the PRP19 complex involved in pre-mRNA splicing, plays an important role in the DNA damage response through the RPA complex, a key regulator in the maintenance of genome integrity. Currently, the physiological role of BCAS2 in mammals is unknown. We now report that BCAS2 responds to endogenous and exogenous DNA damage in mouse zygotes. Maternal depletion of BCAS2 compromises the DNA damage response in early embryos, leading to developmental arrest at the two- to four-cell stage accompanied by the accumulation of damaged DNA and micronuclei. Furthermore, BCAS2 mutants that are unable to bind RPA1 fail in DNA repair during the zygotic stage. In addition, phosphorylated RPA2 cannot localise to the DNA damage sites in mouse zygotes with disrupted maternal BCAS2. These data suggest that BCAS2 might function through the RPA complex during DNA repair in zygotes. Together, our results reveal that maternal BCAS2 maintains the genome integrity of early embryos and is essential for female mouse fertility.

Sex Hormone Metabolism and Threatened Abortion.

BACKGROUND The aim of this study was to evaluate changes in sex hormone metabolism in patients with threatened miscarriage. MATERIAL AND METHODS We recruited 73 women in early pregnancy (6-8 weeks of gestation) and divided them into the following 2 groups based on whether they had vaginal bleeding: group A (n=34), the threatened abortion group; and group B (n=39), the normal pregnancy group. Human chorionic gonadotrophin (hCG), estradiol (E2), progesterone (P4), and testosterone (T) serum levels were tested and sex hormone metabolites in the urine were detected using gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). As the control, data for sex hormones and their metabolites were obtained in normal women of childbearing age without pregnancy (group C: n=23). RESULTS E2 and T serum levels were lower in women with threatened miscarriage (group A). Estrone (E1), E2, estriol (E3), 16α-hydroxyestrone (16α-OHE1), 4-methoxyestrone (4-MeOE1), 2-hydroxyestradiol (2-OHE2), and 4-methoxyestradiol (4-MeOE2) levels were significantly lower in group A (P=0.001, 0.003, 0.009, 0.001, 0.012, 0.032, and 0.047, respectively.). Urine levels of dehydroepiandrosterone (DHEA), androstenedione (A2), and the metabolite of (A2) were also significantly lower in group A (P=0.007, 0.009, and 0.011, respectively). The 2-OHE1/E1, 4-OHE1/E1, 2-MeOE1/E1, and 2-MeOE2/E2 ratios were lower in group B, whereas the 2-OHE2/E2, 4-OHE2/E2, and 4-MeOE2/E2 ratios were dramatically lower in all pregnant women (groups A and B) than in group C. CONCLUSIONS Deficiency in DHEA and abnormal levels of sex hormone metabolites may cause a reduction in the activity of estrogens in women with threatened abortion. These alterations may result in bleeding during the first trimester of pregnancy.

Dehydroepiandrosterone plus climen supplementation shows better effects than dehydroepiandrosterone alone on infertility patients with diminished ovarian reserve of low-FSH level undergoing in-vitro fertilization cycles: a randomized controlled trial.

BACKGROUND: This study aimed to assess the effect of dehydroepiandrosterone (DHEA) plus climen (estradiol valerate and cyproterone acetate drug combination) on infertility patients with diminished ovarian reserve (DOR) and to determine if the combination of DHEA plus climen is superior to DHEA alone in improving ovarian response. METHODS: A total of 124 women were randomized into the DHEA group (n = 64) and the DHEA plus climen group (n = 60) for 12 weeks before being subjected to in-vitro fertilization (IVF) cycles. To investigate if there is a FSH-related difference on the effect of the addition of climen, the DHEA group and the DHEA plus climen group were further divided into four subgroups according to a basal FSH level cut-off of 10 mIU/ml. We performed a comparison of Day 3 blood samples before and after treatment and IVF outcome parameters, including AMH, FSH, E2, AFC, oocytes retrieved, MII oocyte numbers, embryo numbers and accumulated embryo scores. RESULTS: After 12 weeks of pretreatment, the DHEA plus climen group demonstrated a significantly higher level of AMH (P = 0.001) and a significantly lower level of FSH (P = 0.001) compared with the DHEA group. When the two groups were divided into four subgroups based on the FSH cut-off of 10 mIU/mL, a significant increase of AMH (P = 0.034) was found in the high-FSH DHEA plus climen group, whereas there was no significant difference in the high-FSH DHEA group (P = 0.322). A significantly higher accumulated score of embryos was observed in the low-FSH DHEA plus climen group compared with the low-FSH DHEA group (P = 0.034). CONCLUSIONS: These observations suggest that patients with DOR of a low-FSH level might benefit more from DHEA plus climen supplementation than from DHEA supplementation alone.

Lineage regulators TFAP2C and NR5A2 function as bipotency activators in totipotent embryos.

During the first lineage segregation, a mammalian totipotent embryo differentiates into the inner cell mass (ICM) and trophectoderm (TE). However, how transcription factors (TFs) regulate this earliest cell-fate decision in vivo remains elusive, with their regulomes primarily inferred from cultured cells. Here, we investigated the TF regulomes during the first lineage specification in early mouse embryos, spanning the pre-initiation, initiation, commitment, and maintenance phases. Unexpectedly, we found that TFAP2C, a trophoblast regulator, bound and activated both early TE and inner cell mass (ICM) genes at the totipotent (two- to eight-cell) stages ('bipotency activation'). Tfap2c deficiency caused downregulation of early ICM genes, including Nanog, Nr5a2, and Tdgf1, and early TE genes, including Tfeb and Itgb5, in eight-cell embryos. Transcription defects in both ICM and TE lineages were also found in blastocysts, accompanied by increased apoptosis and reduced cell numbers in ICMs. Upon trophoblast commitment, TFAP2C left early ICM genes but acquired binding to late TE genes in blastocysts, where it co-bound with CDX2, and later to extra-embryonic ectoderm (ExE) genes, where it cooperatively co-occupied with the former ICM regulator SOX2. Finally, 'bipotency activation' in totipotent embryos also applied to a pluripotency regulator NR5A2, which similarly bound and activated both ICM and TE lineage genes at the eight-cell stage. These data reveal a unique transcription circuity of totipotency underpinned by highly adaptable lineage regulators.

Pregnancy incidence and associated risk factors of dichorionic triamniotic triplet under assisted reproduction: A large sample of clinical data analysis.

Background: Dichorionic triamniotic (DCTA) triplet pregnancies are rare in spontaneous pregnancy. The aim was to characterize the incidence and risk factors of DCTA triplet pregnancies after assisted reproductive technology (ART). Methods: A retrospective analysis of 10,289 patients, including 3,429 fresh embryo transfer (ET) cycle and 6,860 frozen ET cycle, was performed from January 2015 to June 2020. The effect of different ART parameters on the incidence of DCTA triplet pregnancies was evaluated by multivariate logistic regression analyses. Results: Among all clinical pregnancies after ART, the incidence of DCTA was 1.24%. 1.22% occurred in the fresh ET cycle, while 1.25% occurred in the frozen ET cycle. The number of ET and cycle type has no effect on the occurrence of DCTA triplet pregnancies (p = 0.987; p = 0.056, respectively). There were significant differences in DCTA triplet pregnancies rate among receiving intracytoplasmic sperm injection (ICSI) and receiving in vitro fertilization (IVF) [1.92% vs. 1.02%, p < 0.001, OR = 0.461, 95% confidence interval (CI) 0.315-0.673], blastocyst transfer (BT) versus cleavage-ET (1.66% vs. 0.57%, P < 0.001, OR = 0.329, 95% CI 0.315-0.673), and maternal age ≥ 35 years versus maternal age < 35 years (1.00% vs. 1.30%, P = 0.040, OR = 1.773, 95% CI 1.025-3.066). Based on the regression analysis of cycle type, DCTA triplet pregnancies rate was higher in maternal age < 35 years than in maternal age ≥ 35 years (1.35% vs. 0.97%, P < 0.001, OR = 5.266, 95% CI 2.184-12.701), BT versus cleavage-ET (1.47% vs. 0.94%; P = 0.006, OR = 0.346, 95% CI 0.163-0.735), and receiving ICSI was higher than receiving IVF (3.82% vs. 0.78%, p < 0.001, OR = 0.085, 95% CI 0.039-0.189) in fresh ET cycle. However, DCTA triplet pregnancies rate did not show difference in maternal age, insemination methods, and number of ET, and only BT was found to be associated with a higher DCTA triplet pregnancies rate in the frozen ET cycle (1.73% vs. 0.30%, p < 0.001, OR = 0.179, 95% CI 0.083-0.389). Conclusion: The prevalence of DCTA triplet pregnancies has increased after ART. Maternal age < 35 years, BT, and receiving ICSI are risk factors for DCTA triplet pregnancies, also in fresh ET cycle. However, in frozen ET cycle, BT is an independent risk factor for increased DCTA triplet pregnancies rate.

Maternal TDP-43 interacts with RNA Pol II and regulates zygotic genome activation.

Zygotic genome activation (ZGA) is essential for early embryonic development. However, the regulation of ZGA remains elusive in mammals. Here we report that a maternal factor TDP-43, a nuclear transactive response DNA-binding protein, regulates ZGA through RNA Pol II and is essential for mouse early embryogenesis. Maternal TDP-43 translocates from the cytoplasm into the nucleus at the early two-cell stage when minor to major ZGA transition occurs. Genetic deletion of maternal TDP-43 results in mouse early embryos arrested at the two-cell stage. TDP-43 co-occupies with RNA Pol II as large foci in the nucleus and also at the promoters of ZGA genes at the late two-cell stage. Biochemical evidence indicates that TDP-43 binds Polr2a and Cyclin T1. Depletion of maternal TDP-43 caused the loss of Pol II foci and reduced Pol II binding on chromatin at major ZGA genes, accompanied by defective ZGA. Collectively, our results suggest that maternal TDP-43 is critical for mouse early embryonic development, in part through facilitating the correct RNA Pol II configuration and zygotic genome activation.

Evolutionary epigenomic analyses in mammalian early embryos reveal species-specific innovations and conserved principles of imprinting.

While mouse remains the most popular model, the conservation of parental-to-embryonic epigenetic transition across mammals is poorly defined. Through analysis of oocytes and early embryos in human, bovine, porcine, rat, and mouse, we revealed remarkable species-specific innovations as no single animal model fully recapitulates the human epigenetic transition. In rodent oocytes, transcription-dependent DNA methylation allows methylation of maternal imprints but not intergenic paternal imprints. Unexpectedly, prevalent DNA hypermethylation, paralleled by H3K36me2/3, also occurs in nontranscribed regions in porcine and bovine oocytes, except for megabase-long "CpG continents (CGCs)" where imprinting control regions preferentially reside. Broad H3K4me3 and H3K27me3 domains exist in nonhuman oocytes, yet only rodent H3K27me3 survives beyond genome activation. Coincidently, regulatory elements preferentially evade H3K27me3 in rodent oocytes, and failure to do so causes aberrant embryonic gene repression. Hence, the diverse mammalian innovations of parental-to-embryonic transition center on a delicate "to-methylate-or-not" balance in establishing imprints while protecting other regulatory regions.

Formative pluripotent stem cells show features of epiblast cells poised for gastrulation.

The pluripotency of mammalian early and late epiblast could be recapitulated by naïve embryonic stem cells (ESCs) and primed epiblast stem cells (EpiSCs), respectively. However, these two states of pluripotency may not be sufficient to reflect the full complexity and developmental potency of the epiblast during mammalian early development. Here we report the establishment of self-renewing formative pluripotent stem cells (fPSCs) which manifest features of epiblast cells poised for gastrulation. fPSCs can be established from different mouse ESCs, pre-/early-gastrula epiblasts and induced PSCs. Similar to pre-/early-gastrula epiblasts, fPSCs show the transcriptomic features of formative pluripotency, which are distinct from naïve ESCs and primed EpiSCs. fPSCs show the unique epigenetic states of E6.5 epiblast, including the super-bivalency of a large set of developmental genes. Just like epiblast cells immediately before gastrulation, fPSCs can efficiently differentiate into three germ layers and primordial germ cells (PGCs) in vitro. Thus, fPSCs highlight the feasibility of using PSCs to explore the development of mammalian epiblast.

A novel homozygous nonsense ZP1 variant causes human female infertility associated with empty follicle syndrome (EFS).

BACKGROUND: Empty follicle syndrome (EFS) is a rare but severe condition in which no oocyte is recovered in female patients undergoing in vitro fertilization (IVF) after sufficient ovarian response to hormonal trigger. Accumulating evidence highlights the genetic basis of EFS occurrence. METHODS: In this study, we report a patient with primary infertility showing the characteristics of EFS from a consanguineous family. Under the treatment of assisted reproductive technique (ART), no oocyte was retrieved following the aspiration of mature follicles. Through whole-exome sequencing (WES), we discovered a novel recessively transmitted mutation in ZP1 (c.769 C>T, p. Q257*). RESULTS: In vitro Co-immunoprecipitation assays showed that mutant ZP1 protein failed to interact with either ZP2 or ZP3, which explains the degenerated oocytes in the patient with EFS. CONCLUSION: Together, our data further expand the spectrum of ZP1 mutations that are associated with human EFS and thus provide novel insight into the diagnosis of EFS patients.

Epigenomic analysis of gastrulation identifies a unique chromatin state for primed pluripotency.

Around implantation, the epiblast (Epi) transits from naïve to primed pluripotency, before giving rise to the three germ layers. How chromatin is reconfigured during this developmental window remains poorly understood. We performed a genome-wide investigation of chromatin landscapes during this period. We find that enhancers in ectoderm are already pre-accessible in embryonic day 6.5 (E6.5) Epi when cells enter a primed pluripotent state. Unexpectedly, strong trimethylation of histone H3 at lysine 4 (H3K4me3) emerges at developmental gene promoters in E6.5 Epi and positively correlates with H3K27me3, thus establishing bivalency. These genes also show enhanced spatial interactions. Both the strong bivalency and spatial clustering are virtually absent in preimplantation embryos and are markedly reduced in fate-committed lineages. Finally, we show that KMT2B is essential for establishing bivalent H3K4me3 at E6.5 but becomes partially dispensable later. Its deficiency leads to impaired activation of developmental genes and subsequent embryonic lethality. Thus, our data characterize lineage-specific chromatin reconfiguration and a unique chromatin state for primed pluripotency.

Clinical outcomes following long GnRHa ovarian stimulation with highly purified human menopausal gonadotropin plus rFSH or rFSH in patients undergoing in vitro fertilization-embryo transfer: a multi-center randomized controlled trial.

BACKGROUND: This clinical trial aimed to compare the clinical efficacy of highly purified human menopausal gonadotropin (HP-HMG) plus recombinant human follicle-stimulating hormone (rFSH) versus rFSH alone on controlled ovarian stimulation (COS) in vitro fertilization-embryo transfer (IVF-ET). METHODS: A total of 610 women underwent long gonadotropin-releasing hormone (GnRH) agonist protocol for IVF treatment. The subjects were randomized into 2 groups: HP-HMG + rFSH group (n=305) and rFSH group (n=305). The main outcome was the progesterone (P) level on the day of HCG injection. RESULTS: There was no significant difference in terms of the demographic and baseline characters between the two groups. In rFSH group, the P level on the day of HCG trigger were significantly higher than that of HP-HMG+rFSH group (4.3±2.2 vs. 3.8±1.7 nmol/L, P<0.001). The fertilization rate in rFSH group was significantly lower than that of HP-HMG + rFSH group (69.2% vs. 73.9%, P<0.001). Simultaneously, the percentage of cycles with fresh embryo transfer in rFSH group was also significantly lower than that of HP-HMG + rFSH group (49.6% vs. 57.5%, P=0.007). However, there was no difference in terms of cleavage rate, implantation rate, clinical pregnancy rate and ovarian hyperstimulation syndrome (OHSS) rate between two groups. CONCLUSIONS: The use of combined HP-HMG with FSH may be superior to rFSH alone in stimulating the ovary in normal responders undergoing IVF treatment. Furthermore, the further prospective studies with large sample are still needed to confirm the study.