DPPA3 facilitates genome-wide DNA demethylation in mouse primordial germ cells

BACKGROUND

Genome-wide DNA demethylation occurs in mammalian primordial germ cells (PGCs) as part of the epigenetic reprogramming important for gametogenesis and resetting the epigenetic information for totipotency. Dppa3 (also known as Stella or Pgc7) is highly expressed in mouse PGCs and oocytes and encodes a factor essential for female fertility. It prevents excessive DNA methylation in oocytes and ensures proper gene expression in preimplantation embryos: however, its role in PGCs is largely unexplored. In the present study, we investigated whether or not DPPA3 has an impact on CG methylation/demethylation in mouse PGCs.

RESULTS

We show that DPPA3 plays a role in genome-wide demethylation in PGCs even before sex differentiation. Dppa3 knockout female PGCs show aberrant hypermethylation, most predominantly at H3K9me3-marked retrotransposons, which persists up to the fully-grown oocyte stage. DPPA3 works downstream of PRDM14, a master regulator of epigenetic reprogramming in embryonic stem cells and PGCs, and independently of TET1, an enzyme that hydroxylates 5-methylcytosine.

CONCLUSIONS

The results suggest that DPPA3 facilitates DNA demethylation through a replication-coupled passive mechanism in PGCs. Our study identifies DPPA3 as a novel epigenetic reprogramming factor in mouse PGCs.

Epigenetic plasticity safeguards heterochromatin configuration in mammals

Heterochromatin is a key architectural feature of eukaryotic chromosomes critical for cell type-specific gene expression and genome stability. In the mammalian nucleus, heterochromatin segregates from transcriptionally active genomic regions and exists in large, condensed, and inactive nuclear compartments. However, the mechanisms underlying the spatial organization of heterochromatin need to be better understood. Histone H3 lysine 9 trimethylation (H3K9me3) and lysine 27 trimethylation (H3K27me3) are two major epigenetic modifications that enrich constitutive and facultative heterochromatin, respectively. Mammals have at least five H3K9 methyltransferases (SUV39H1, SUV39H2, SETDB1, G9a and GLP) and two H3K27 methyltransferases (EZH1 and EZH2). In this study, we addressed the role of H3K9 and H3K27 methylation in heterochromatin organization using a combination of mutant cells for five H3K9 methyltransferases and an EZH1/2 dual inhibitor, DS3201. We showed that H3K27me3, which is normally segregated from H3K9me3, was redistributed to regions targeted by H3K9me3 after the loss of H3K9 methylation and that the loss of both H3K9 and H3K27 methylation resulted in impaired condensation and spatial organization of heterochromatin. Our data demonstrate that the H3K27me3 pathway safeguards heterochromatin organization after the loss of H3K9 methylation in mammalian cells.

Conservation and divergence of canonical and non-canonical imprinting in murids

BACKGROUND

Genomic imprinting affects gene expression in a parent-of-origin manner and has a profound impact on complex traits including growth and behavior. While the rat is widely used to model human pathophysiology, few imprinted genes have been identified in this murid. To systematically identify imprinted genes and genomic imprints in the rat, we use low input methods for genome-wide analyses of gene expression and DNA methylation to profile embryonic and extraembryonic tissues at allele-specific resolution.

RESULTS

We identify 14 and 26 imprinted genes in these tissues, respectively, with 10 of these genes imprinted in both tissues. Comparative analyses with mouse reveal that orthologous imprinted gene expression and associated canonical DNA methylation imprints are conserved in the embryo proper of the Muridae family. However, only 3 paternally expressed imprinted genes are conserved in the extraembryonic tissue of murids, all of which are associated with non-canonical H3K27me3 imprints. The discovery of 8 novel non-canonical imprinted genes unique to the rat is consistent with more rapid evolution of extraembryonic imprinting. Meta-analysis of novel imprinted genes reveals multiple mechanisms by which species-specific imprinted expression may be established, including H3K27me3 deposition in the oocyte, the appearance of ZFP57 binding motifs, and the insertion of endogenous retroviral promoters.

CONCLUSIONS

In summary, we provide an expanded list of imprinted loci in the rat, reveal the extent of conservation of imprinted gene expression, and identify potential mechanisms responsible for the evolution of species-specific imprinting.

Noncanonical imprinting: intergenerational epigenetic inheritance mediated by Polycomb complexes

Genomic imprinting is illustrative of intergenerational epigenetic inheritance. The passage of parental genomes into the embryo is accompanied by epigenetic modifications, resulting in imprinted monoallelic gene expression in mammals. Some imprinted genes are regulated by maternal inheritance of H3K27me3, which is termed noncanonical imprinting. Noncanonical imprinting is established by Polycomb repressive complexes during oogenesis and maintained in preimplantation embryos and extraembryonic tissues, including the placenta. Recent studies of noncanonical imprinting have contributed to our understanding of chromatin regulation in oocytes and early embryos, imprinted X-chromosome inactivation, secondary differentially DNA-methylated regions, and the anomalies of cloned mice. Here, I summarize the current knowledge of noncanonical imprinting and remark on analogous mechanisms in invertebrates and plants.

RIB induced reactions: Studying astrophysical reactions with low-energy RI beam at CRIB

Astrophysical reactions involving radioactive isotopes (RI) often play an important role in high-temperature stellar environments. The experimental studies on the reaction rates for those are still limited mainly due to the technical difficulties in producing high-quality RI beams. A direct measurement of those reactions would be still challenging in many cases, however, we can make a reliable evaluation of the reaction rates by an indirect method or by studying the resonance prorerties. Here we ntroduce recent examples of experimental studies on such RI-involving astrophysical reactions, performed at Center for Nuclear Study, the University of Tokyo, using the low-energy RI beam separator CRIB. One is for the neutron-induced destruction reactions of 7Be in the Big-Bang nucleosynthesis, and the other is the study on the 22Mg(α, p) reaction relevant in X-ray bursts, which was performed with the resonant scattering method from the inverse reaction channel.

Low-Input CUT&RUN for Mouse Oocytes and Preimplantation Embryos

Cleavage Under Target & Release Using Nuclease (CUT&RUN) enables the detection of DNA regions that are bound by a protein of interest. This method is suitable for low-input materials because of the absence of an immunoprecipitation step. However, it sometimes fails when applying it to fragile cells, such as mouse oocytes. Here we describe our low-input CUT&RUN protocol optimized for mouse oocyte and preimplantation embryo samples in which the primary antibody and protein A-MNase binding steps are completed before the cells are bound to Concanavalin A-coated magnetic beads. This modification prevents crush of oocytes and early embryos and unwanted loss of chromatin during CUT&RUN procedures.

Transcriptomic signatures in trophectoderm and inner cell mass of human blastocysts classified according to developmental potential, maternal age and morphology

Selection of high-quality embryos is important to achieve successful pregnancy in assisted reproductive technology (ART). Recently, it has been debated whether RNA-sequencing (RNA-Seq) should be applied to ART to predict embryo quality. However, information on genes that can serve as markers for pregnant expectancy is limited. Furthermore, there is no information on which transcriptome of trophectoderm (TE) or inner cell mass (ICM) is more highly correlated with pregnant expectancy. Here, we performed RNA-Seq analysis of TE and ICM of human blastocysts, the pregnancy expectation of which was retrospectively determined using the clinical outcomes of 1,890 cases of frozen-thawed blastocyst transfer. We identified genes that were correlated with the expected pregnancy rate in ICM and TE, respectively, with a larger number of genes identified in TE than in ICM. Downregulated genes in the TE of blastocysts that were estimated to have lower expectation of pregnancy included tight junction-related genes such as CXADR and ATP1B1, which have been implicated in peri-implantation development. Moreover, we identified dozens of differentially expressed genes by regrouping the blastocysts based on the maternal age and the Gardner score. Additionally, we showed that aneuploidy estimation using RNA-Seq datasets does not correlate with pregnancy expectation. Thus, our study provides an expanded list of candidate genes for the prediction of pregnancy in human blastocyst embryos.

Data-driven control for multi-rate multi-input/single-output systems

For the next generation of manufacturing, represented by Industrie 4.0, a multi-input controller is designed directly from controlled data, without using the mathematical plant model, where the ratio between the D/A conversion of multiple inputs and the A/D conversion of a single output is non-uniquely. With the proposed method, the fixed-structured controller is optimally designed by solving a model reference problem using one-shot data. Furthermore, to eliminate inter-sample ripples emerged by input oscillation, the deviation of the control inputs is also evaluated using the proposed method. As a result, a non-ripple data-driven controller is achieved. Numerical examples show that the proposed multi-rate data-driven method is superior than the conventional single-rate method.

P-138 Transcriptomic signatures in trophectoderm and inner cell mass of human blastocysts with expected pregnancy rates

Study question

Is it possible to identify the molecular factors that contribute to the implantation potential of blastocysts?

Summary answer

Genes correlated with expected pregnancy rate in trophectoderm (TE) and inner cell mass (ICM) respectively were identified, and aneuploidy alone couldn’t predict the pregnancy expectation.

What is known already

The selection of suitable embryos for transfer is critical for achieving successful pregnancy outcomes in assisted reproductive technology (ART). Although pre-implantation genetic testing for aneuploidy (PGT-A) as well as morphological and chronological evaluation of embryos, have been conducted in clinical practice, they do not fully guarantee successful pregnancy. Recently, transcriptional events in early human embryonic development have been analyzed using RNA-sequencing (RNA-seq) and researchers are attempting to apply this information to ART.

Study design, size, duration

To determine the correlation between blastocyst evaluation and pregnancy rate, we retrospectively analyzed 1,890 cases underwent frozen-thawed blastocyst transfer from March 2018 to December 2020. A total of 13 blastocysts that were cryopreserved for clinical use between February 2011 and September 2018, then scheduled for disposal and with consented for research, were subjected to RNA-seq without distinguishing between conventional in vitro fertilization (c-IVF) and intracytoplasmic sperm injection (ICSI).

Participants/materials, setting, methods

Blastocysts were donated by infertile couples undergoing c-IVF or ICSI cycles at the Yamashita Shonan Yume Clinic with informed consent under ethical approval. TE and ICM cells were collected from blastocysts by using a micromanipulator and then subjected to RNA-seq. Gene expression analysis and digital karyotyping using RNA-seq were performed simultaneously for TE and ICM cells, respectively. One-way analysis of variance, chi-square test and Tukey's multiple comparison test were used for this study.

Main results and the role of chance

Blastocysts were classified into three groups to correlate with pregnancy rates based on the diameter of the blastocyst and the time to reach this size: those taking less than 130 h to reach a diameter of > 170 μm (Group 1, n = 676), those taking more than 140 h to reach a diameter of < 180 μm (Group 2, n = 158), and the rest (Group 3, n = 1,056). The pregnancy rates of Groups 1, 2 and 3 were 59.0%, 16.5%, and 34.2%, respectively (p < 0.01). Assessing the differences in overall transcripts correlated between Group 1 (n = 5), Group 2 (n = 4), and Group 3 (n = 4), 26 and 67 differentially expressed genes (DEGs) were identified in ICM and TE cells, respectively. Importantly, downregulated genes in TE of blastocysts with lower expectation of pregnancy included tight junction-related genes, such as CXADR, CLDN10, and ATP1B1, which were implicated in peri-implantation development. Digital karyotyping revealed karyotypic abnormalities and mosaicism in all groups with no common abnormalities observed, suggesting that aneuploidy alone cannot predict the pregnancy expectation.

Limitations, reasons for caution

Although 93 genes potentially related to implantation have been identified, it is still unclear how these genes are involved in implantation. In vitro implantation models using human embryos and artificial embryos currently under development are expected to contribute to the elucidation of the functions of these genes.

Wider implications of the findings

Our results provide reliable candidates for genes that could allow for non-invasive selection of high-quality blastocysts for ART and add to the knowledge base of transcriptional events in human peri-implantation development.

Trial registration number

not applicable

Integrative analysis of scRNA-seq and scATAC-seq revealed transit-amplifying thymic epithelial cells expressing autoimmune regulator

Medullary thymic epithelial cells (mTECs) are critical for self-tolerance induction in T cells via promiscuous expression of tissue-specific antigens (TSAs), which are controlled by the transcriptional regulator, AIRE. Whereas AIRE-expressing (Aire⁺) mTECs undergo constant turnover in the adult thymus, mechanisms underlying differentiation of postnatal mTECs remain to be discovered. Integrative analysis of single-cell assays for transposase-accessible chromatin (scATAC-seq) and single-cell RNA sequencing (scRNA-seq) suggested the presence of proliferating mTECs with a specific chromatin structure, which express high levels of Aire and co-stimulatory molecules, CD80 (Aire⁺CD80^hi). Proliferating Aire⁺CD80^hi mTECs detected using Fucci technology express a minimal number of Aire-dependent TSAs and are converted into quiescent Aire⁺CD80^hi mTECs expressing high levels of TSAs after a transit amplification. These data provide evidence for the existence of transit-amplifying Aire⁺mTEC precursors during the Aire⁺mTEC differentiation process of the postnatal thymus.

Noncanonical imprinting sustains embryonic development and restrains placental overgrowth

In this study, Matoba et al. use a combinatorial maternal KO of Xist, a noncanonical imprinted gene whose LOI causes aberrant transient maternal X-chromosome inactivation (XCI) at preimplantation, and show that prevention of the transient maternal XCI greatly restores the development of Eed matKO embryos. Their findings provide evidence that Xist imprinting sustains embryonic development and that autosomal noncanonical imprinting restrains placental overgrowth.

Genomic imprinting regulates parental origin-dependent monoallelic gene expression. It is mediated by either germline differential methylation of DNA (canonical imprinting) or oocyte-derived H3K27me3 (noncanonical imprinting) in mice. Depletion of Eed, an essential component of Polycomb repressive complex 2, results in genome-wide loss of H3K27me3 in oocytes, which causes loss of noncanonical imprinting (LOI) in embryos. Although Eed maternal KO (matKO) embryos show partial lethality after implantation, it is unknown whether LOI itself contributes to the developmental phenotypes of these embryos, which makes it unclear whether noncanonical imprinting is developmentally relevant. Here, by combinatorial matKO of Xist, a noncanonical imprinted gene whose LOI causes aberrant transient maternal X-chromosome inactivation (XCI) at preimplantation, we show that prevention of the transient maternal XCI greatly restores the development of Eed matKO embryos. Moreover, we found that the placentae of Eed matKO embryos are remarkably enlarged in a manner independent of Xist LOI. Heterozygous deletion screening of individual autosomal noncanonical imprinted genes suggests that LOI of the Sfmbt2 miRNA cluster chromosome 2 miRNA cluster (C2MC), solute carrier family 38 member 4 (Slc38a4), and Gm32885 contributes to the placental enlargement. Taken together, our study provides evidence that Xist imprinting sustains embryonic development and that autosomal noncanonical imprinting restrains placental overgrowth.

Experimental studies on astrophysical reactions at the low-energy RI beam separator CRIB

Experimental studies on astrophysical reactions involving radioactive isotopes (RI) often accompany technical challenges. Studies on such nuclear reactions have been conducted at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study, the University of Tokyo. We discuss two cases of astrophysical reaction studies at CRIB; one is for the 7Be+n reactions which may affect the primordial 7Li abundance in the Big-Bang nucleosynthesis, and the other is for the 22Mg(α, p) reaction relevantin X-raybursts.

Formation of α clusters in dilute neutron-rich matter

The surface of neutron-rich heavy nuclei, with a neutron skin created by excess neutrons, provides an important terrestrial model system to study dilute neutron-rich matter. By using quasi-free α cluster-knockout reactions, we obtained direct experimental evidence for the formation of α clusters at the surface of neutron-rich tin isotopes. The observed monotonous decrease of the reaction cross sections with increasing mass number, in excellent agreement with the theoretical prediction, implies a tight interplay between α-cluster formation and the neutron skin. This result, in turn, calls for a revision of the correlation between the neutron-skin thickness and the density dependence of the symmetry energy, which is essential for understanding neutron stars. Our result also provides a natural explanation for the origin of α particles in α decay.

Low-noise radio over graded-index plastic optical fiber

We developed a graded-index plastic optical fiber (GI POF) that enables lower-noise radio frequency (RF) transmission than conventional multimode fibers for short-distance household applications (<100m). It is shown that reflection noise degrades RF transmission, regardless of the carrier frequency, through the spurious generation that accompanies the RF modulation of a vertical-cavity surface-emitting laser. The GI POF with distinctive mode coupling, which is closely related to its microscopic polymer structure, suppresses noise and spurious generation to improve transmission quality. Our low-noise radio-over-GI-POF technology will offer significant advantages for optical wiring systems for broadcast and communication in small- and medium-scale buildings.

Combined Impact of Physical Frailty and Social Isolation on Rate of Falls in Older Adults

OBJECTIVES

The aim of this study was to examine the impact of the combination of physical frailty and social isolation on falling in community-dwelling older adults.

DESIGN

A cross-sectional study of data obtained at registration in a randomized control trial.

SETTING

Community-based study of participants recruited from Toyota, Japan.

PARTICIPANTS

380 community-dwelling older adults (47.9% women, mean age = 72.3 ± 4.6 years).

MEASUREMENTS

Participants were categorized as non-frail or pre-frail/frail based on the Fried frailty criteria (slowness, weakness, exhaustion, low activity, and weight loss). Social isolation was examined using the Lubben Social Network Scale (LSNS-6), and scores lower than 12 points indicated social isolation. Participants were divided into four groups depending on pre-frail/frail status and social isolation, and experiences of multiple falls over the past year were compared between the groups.

RESULTS

Participants were classified into robust (n = 193), physical frailty (PF; n = 108), social isolation (SI; n = 43), and PF with SI (PF+SI; n = 36) groups. A total of 38 (10.0%) participants reported multiple falls. Logistic regression analysis showed that PF and SI groups were not independently associated with falling (PF: OR 1.64, 95% CI 0.65-4.16, SI: OR 2.25, 95% CI 0.77-6.58), while PF+SI group was significantly associated with falling compared with the robust group (OR 3.06, 95% CI 1.00-9.34, p = 0.049) after controlling for confounding factors.

CONCLUSION

Our findings support the assertion that coexistence with physical frailty and social isolation were associated with falling in the older adults.

Loss of Ikbkap/Elp1 in mouse oocytes causes spindle disorganization, developmental defects in preimplantation embryos and impaired female fertility

Elongator complexes are well known to be involved in a wide variety of cellular processes; however, their functions in mammalian oocytes have not been characterized. Here, we demonstrated in mice that specific deletion of one of the core subunits, Ikbkap/Elp1, in oocytes resulted in spindle defects and chromosome disorganization without affecting folliculogenesis. In accordance with these findings, we observed that Ikbkap mutant female mice are subfertile. Further analyses uncovered that kinetochore–microtubule attachments are severely compromised in Ikbkap-deficient oocytes. Moreover, we revealed that Ikbkap modulates the acetylation status of α-tubulin in oocytes, which may at least in part mediate the meiotic phenotypes described above by affecting microtubule dynamics and kinetochore function. Finally, we showed that embryos derived from Ikbkap-deficient oocytes exhibit an increased frequency of aneuploidy, digyny, progressive delays in preimplantation development, and severe degeneration before reaching the blastocyst stage. In summary, we identify Ikbkap as an important player in regulating oocyte meiosis by modulating tubulin acetylation for chromosome/spindle organization.

Reprogramming of Chromatin Accessibility in Somatic Cell Nuclear Transfer Is DNA Replication Independent

Mammalian oocytes have the ability to reset the transcriptional program of differentiated somatic cells into that of totipotent embryos through somatic cell nuclear transfer (SCNT). However, the mechanisms underlying SCNT-mediated reprogramming are largely unknown. To understand the mechanisms governing chromatin reprogramming during SCNT, we profiled DNase I hypersensitive sites (DHSs) in donor cumulus cells and one-cell stage SCNT embryos. To our surprise, the chromatin accessibility landscape of the donor cells is drastically changed to recapitulate that of the in vitro fertilization (IVF)-derived zygotes within 12 hr. Interestingly, this DHS reprogramming takes place even in the presence of a DNA replication inhibitor, suggesting that SCNT-mediated DHS reprogramming is independent of DNA replication. Thus, this study not only reveals the rapid and drastic nature of the changes in chromatin accessibility through SCNT but also establishes a DNA replication-independent model for studying cellular reprogramming.

Allelic H3K27me3 to allelic DNA methylation switch maintains noncanonical imprinting in extraembryonic cells

Faithful maintenance of genomic imprinting is essential for mammalian development. While germline DNA methylation-dependent (canonical) imprinting is relatively stable during development, the recently found oocyte-derived H3K27me3-mediated noncanonical imprinting is mostly transient in early embryos, with some genes important for placental development maintaining imprinted expression in the extraembryonic lineage. How these noncanonical imprinted genes maintain their extraembryonic-specific imprinting is unknown. Here, we report that maintenance of noncanonical imprinting requires maternal allele-specific de novo DNA methylation [i.e., somatic differentially methylated regions (DMRs)] at implantation. The somatic DMRs are located at the gene promoters, with paternal allele-specific H3K4me3 established during preimplantation development. Genetic manipulation revealed that both maternal EED and zygotic DNMT3A/3B are required for establishing somatic DMRs and maintaining noncanonical imprinting. Thus, our study not only reveals the mechanism underlying noncanonical imprinting maintenance but also sheds light on how histone modifications in oocytes may shape somatic DMRs in postimplantation embryos.

Acyl-CoA synthetase 6 regulates long-chain polyunsaturated fatty acid composition of membrane phospholipids in spermatids and supports normal spermatogenic processes in mice

Long-chain polyunsaturated fatty acids (LCPUFAs), such as docosahexaenoic acid (DHA, 22:6) and docosapentaenoic acid (DPA, 22:5), have versatile physiologic functions. Studies have suggested that DHA and DPA are beneficial for maintaining sperm quality. However, their mechanisms of action are still unclear because of the poor understanding of DHA/DPA metabolism in the testis. DHA and DPA are mainly stored as LCPUFA-containing phospholipids and support normal spermatogenesis. Long-chain acyl-conenzyme A (CoA) synthetase (ACSL) 6 is an enzyme that preferentially converts LCPUFA into LCPUFA-CoA. Here, we report that ACSL6 knockout (KO) mice display severe male infertility due to attenuated sperm numbers and function. ACSL6 is highly expressed in differentiating spermatids, and ACSL6 KO mice have reduced LCPUFA-containing phospholipids in their spermatids. Delayed sperm release and apoptosis of differentiated spermatids were observed in these mice. The results of this study indicate that ACSL6 contributes to the local accumulation of DHA- and DPA-containing phospholipids in spermatids to support normal spermatogenesis.—Shishikura, K., Kuroha, S., Matsueda, S., Iseki, H., Matsui, T., Inoue, A., Arita, M. Acyl-CoA synthetase 6 regulates long-chain polyunsaturated fatty acid composition of membrane phospholipids in spermatids and supports normal spermatogenic processes in mice.

P5320Reduction in high-sensitivity C-reactive protein by pitavastatin was associated with improved outcomes in Japanese patients with stable coronary artery disease: results from REAL-CAD study

Background

The effect of statins on lowering high sensitivity C-reactive protein (hs-CRP) as well as low density lipoprotein cholesterol (LDL-C) has been associated with reduced risk for cardiovascular events in patients with elevated hs-CRP. However, it remains unclear whether this statin effect applies to low-risk patients with stable coronary artery disease (CAD). In this pre-specified sub-study within the REAL-CAD trial, we explored the association between achieved LDL-C/hs-CRP levels and cardiovascular events in Japanese patients with stable CAD who were treated with pitavastatin 1 mg or 4 mg/day.

Methods

The REAL-CAD trial randomly allocated 13,054 patients with stable CAD to pitavastatin 1 mg or 4 mg/day. LDL-C and hs-CRP were measured at baseline and at 6 months after randomization. We excluded those patients without 6-month data and those with endpoint events before 6 months (N=1915). The primary endpoint of the study was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal ischemic stroke, or unstable angina requiring emergency hospitalization. Outcomes were assessed by landmark analysis beyond 6 months among 4 groups that were configured based on LDL-C (median) and hs-CRP (median) targets: achieving neither target, achieving LDL-C target only, achieving hs-CRP target only, and achieving both targets. Data were adjusted for baseline characteristics including age, gender, diabetes and baseline values of LDL-C and hs-CRP.

Results

Median LDL-C and hs-CRP levels were 88 mg/dL and 0.52 mg/L at baseline and 80 mg/dL and 0.48 mg/L after 6 months, respectively. There was no correlation between the change in LDL-C and hs-CRP levels from baseline to 6 months (correlation coefficient: 0.009, P=0.331). Of the 11,677 patients included in the study, 25.1% (N=2799) achieved both LDL-C and hs-CRP targets, 25.3% (N=2282) met neither target, 24.8% (N=2765) met only the hs-CRP target, and 24.7% (N=2753) met only the LDL-C target. Risk of primary endpoint occurrence was significantly lower in those achieving either or both targets than in those meeting neither target (Figure A). In the subgroup analysis stratified by the randomized dose of pitavastatin, the risk for the primary endpoint was significantly lower in patients achieving both targets in both the 1mg and 4 mg arms, and in patients achieving only hs-CRP target in the 1 mg arm (Figure B, C).

Figure 1

Conclusions

In this subanalysis of the REAL-CAD trial, the hs-CRP lowering effect of pitavastatin was independent from LDL-C lowering. Lower achieved hs-CRP was associated with lower risk for cardiovascular events in Japanese patients with stable CAD.

Acknowledgement/Funding

Public Health Research Foundation, The company manufacturing the study drug (Kowa Pharmaceutical Co Ltd) was one of the entities providing financial s

Unconventional plastic optical fiber design for very short multimode fiber link

We introduce a graded-index plastic optical fiber (GI POF) design for very short-distance household applications, in which the transmission quality is predominantly determined by system noise rather than the loss and bandwidth. The developed GI POF has strong mode coupling with low accompanying scattering loss, which is closely related to the specific microscopic heterogeneities in the core material. Such characteristic mode coupling significantly decreases reflection noise, improving the transmission quality compared with silica GI multimode fiber (MMF) for lengths below 30 m. Moreover, in the GI POF link, the transmission quality tends to improve with increasing fiber length, despite the increased loss and decreased bandwidth. This feature suggests that the system noise can be controlled by the microscopic heterogeneous properties of the GI POF for a very short MMF link, where the fiber loss and bandwidth are sufficiently low and high, respectively. This unconventional concept for optical-fiber design can advance fiber-optic communication in emerging applications in households located near optical network terminals.

Maternal Eed knockout causes loss of H3K27me3 imprinting and random X inactivation in the extraembryonic cells

In this study, Inoue et al. investigated the regulatory mechanisms and functions of the maternal H3K27me3 mechanism. They found that maternal Eed, an essential component of the Polycomb group complex 2 (PRC2), is required for establishing H3K27me3 imprinting, and their results also reveal unique XCI dynamics in the absence of Xist imprinting.

Genomic imprinting is essential for mammalian development. Recent studies have revealed that maternal histone H3 Lys27 trimethylation (H3K27me3) can mediate DNA methylation-independent genomic imprinting. However, the regulatory mechanisms and functions of this new imprinting mechanism are largely unknown. Here we demonstrate that maternal Eed, an essential component of the Polycomb group complex 2 (PRC2), is required for establishing H3K27me3 imprinting. We found that all H3K27me3-imprinted genes, including Xist, lose their imprinted expression in Eed maternal knockout (matKO) embryos, resulting in male-biased lethality. Surprisingly, although maternal X-chromosome inactivation (XmCI) occurs in Eed matKO embryos at preimplantation due to loss of Xist imprinting, it is resolved at peri-implantation. Ultimately, both X chromosomes are reactivated in the embryonic cell lineage prior to random XCI, and only a single X chromosome undergoes random XCI in the extraembryonic cell lineage. Thus, our study not only demonstrates an essential role of Eed in H3K27me3 imprinting establishment but also reveals a unique XCI dynamic in the absence of Xist imprinting.

Evidence for prevalent Z = 6 magic number in neutron-rich carbon isotopes

The nuclear shell structure, which originates in the nearly independent motion of nucleons in an average potential, provides an important guide for our understanding of nuclear structure and the underlying nuclear forces. Its most remarkable fingerprint is the existence of the so-called magic numbers of protons and neutrons associated with extra stability. Although the introduction of a phenomenological spin-orbit (SO) coupling force in 1949 helped in explaining the magic numbers, its origins are still open questions. Here, we present experimental evidence for the smallest SO-originated magic number (subshell closure) at the proton number six in 13-20C obtained from systematic analysis of point-proton distribution radii, electromagnetic transition rates and atomic masses of light nuclei. Performing ab initio calculations on 14,15C, we show that the observed proton distribution radii and subshell closure can be explained by the state-of-the-art nuclear theory with chiral nucleon-nucleon and three-nucleon forces, which are rooted in the quantum chromodynamics.

Transcriptional activation of transposable elements in mouse zygotes is independent of Tet3-mediated 5-methylcytosine oxidation

This corrects the article DOI: 10.1038/cr.2012.160.

Study of the contribution of the 7Be(d, p) reaction to the 7Li problem in the Big-Bang Nucleosynthesis

Our research goal is to measure the 7Be(d, p) reaction to shed light on the 7Li problem in the Big-Bang Nucleosynthesis. We are developing an unstable 7Be target for a high-resolution measurement of the 7Be(d, p)8Be reaction. We plan to compare two methods to producethe 7Be target: (1) Activation method, and (2) Implantation method. We performed an activation methodexperiment at the Van de Graaff at Osaka University, and obtained the cross-section data. A second experiment to obtain more accurate data will take place at the Tandem Electrostatic Accelerator, Kobe University. We have also made a 7Be target with implantation method at CRIB, Center for Nuclear Study, Univer-sity of Tokyo. An experiment to measure the (d, p) reaction with the implanted target is scheduled for 2018 at Japan Atomic Energy Agency, tandem facility.

Genomic imprinting of Xist by maternal H3K27me3

In this study, Inoue et al. investigated the mechanism underlying Xist imprinting in female mammals. They demonstrate that the Xist locus is coated with a broad H3K27me3 domain that is established during oocyte growth and persists through preimplantation development in mice, thus identifying maternal H3K27me3 as the imprinting mark of Xist.

Maternal imprinting at the Xist gene is essential to achieve paternal allele-specific imprinted X-chromosome inactivation (XCI) in female mammals. However, the mechanism underlying Xist imprinting is unclear. Here we show that the Xist locus is coated with a broad H3K27me3 domain that is established during oocyte growth and persists through preimplantation development in mice. Loss of maternal H3K27me3 induces maternal Xist expression and maternal XCI in preimplantation embryos. Our study thus identifies maternal H3K27me3 as the imprinting mark of Xist.

Clinical and functional significance of STEAP4-splice variant in CD14+ monocytes in patients with rheumatoid arthritis

Tumour necrosis factor alpha (TNF)-α-induced adipose-related protein (TIARP) is a negative regulator of inflammation in arthritis model mice. In humans, six-transmembrane epithelial antigen of prostate 4 (STEAP4) (human counterpart of TIARP) is also expressed in CD14⁺ monocytes from patients with rheumatoid arthritis (RA). Recently, highly levels of exon 3-spliced variant STEAP4 (v-STEAP4) expression have been observed in porcine lung. The aim of this study is to elucidate the expression and functional role of v-STEAP4, comparing it with that of STEAP4, in the pathogenesis of arthritis. We identified v-STEAP4 in CD14⁺ cells. The expression of STEAP4 and v-STEAP4 was higher in patients with RA than in healthy participants. We also found that STEAP4 and v-STEAP4 were correlated positively with C-reactive protein and that their expression was decreased after treatment with an interleukin (IL)-6 antagonist in patients with RA. To investigate further the role of STEAP4 and v-STEAP4, we produced STEAP4 and v-STEAP4 over-expressing human monocytic cell lines (THP-1) for functional analysis. In the v-STEAP4 over-expressing cells, the production of IL-6 was suppressed significantly, but TNF-α was increased significantly through lipopolysaccharide (LPS) stimulation. Immunoblot analysis revealed that phosphorylated (p-)nuclear factor kappa B (NF-κB) was increased after LPS stimulation and degradation of nuclear factor kappa B inhibitor alpha (IκBα) was sustained, whereas p-signal transducer and activator of transcription 3 (STAT-3) was decreased with v-STEAP4. We identified specific up-regulation of v-STEAP4 in RA monocytes. V-STEAP4 might play a crucial role in the production of TNF-α and IL-6 through NF-κB and STAT-3 pathways, resulting in the generation of RA.

Maternal H3K27me3 controls DNA methylation-independent imprinting

Mammalian sperm and oocytes have different epigenetic landscapes and are organized in different fashion. Following fertilization, the initially distinct parental epigenomes become largely equalized with the exception of certain loci including imprinting control regions (ICRs). How parental chromatin becomes equalized and how ICRs escape from this reprogramming is largely unknown. Here we profiled parental allele-specific DNase I hypersensitive sites (DHSs) in mouse zygotes and morula embryos, and investigated the epigenetic mechanisms underlying allelic DHSs. Integrated analyses of DNA methylome and H3K27me3 ChIP-seq data sets revealed 76 genes with paternal allele-specific DHSs that are devoid of DNA methylation but harbor maternal allele-specific H3K27me3. Interestingly, these genes are paternally expressed in preimplantation embryos, and ectopic removal of H3K27me3 induces maternal allele expression. H3K27me3-dependent imprinting is largely lost in the embryonic cell lineage, but at least 5 genes maintain their imprinting in the extra-embryonic cell lineage. The 5 genes include all previously identified DNA methylation-independent imprinted autosomal genes. Thus, our study identifies maternal H3K27me3 as a DNA methylation-independent imprinting mechanism.

Novel Heating-Induced Reversion during Crystallization of Al-based Glassy Alloys

Thermal stability and crystallization of three multicomponent glassy alloys, Al₈₆Y₇Ni₅Co₁Fe_0.5Pd_0.5, Al₈₅Y₈Ni₅Co₁Fe_0.5Pd_0.5 and Al₈₄Y₉Ni₄Co_1.5Fe_0.5Pd₁, were examined to assess the ability to form the mixture of amorphous (am) and fcc-aluminum (α-Al) phases. On heating, the glass transition into the supercooled liquid is shown by the 85Al and 84Al glasses. The crystallization sequences are [am] → [am + α-Al] → [α-Al + compounds] for the 86Al and 85Al alloys, and [am] → [am + α-Al + cubic Al_xM_y (M = Y, Ni, Co, Fe, Pd)] → [am + α-Al] → [α-Al + Al₃Y + Al₉(Co, Ni)₂ + unknown phase] for the 84Al alloy. The glass transition appears even for the 85Al alloy where the primary phase is α-Al. The heating-induced reversion from [am + α-Al + multicomponent Al_xM_y] to [am + α-Al] for the 84Al alloy is abnormal, not previously observed in crystallization of glassy alloys, and seems to originate from instability of the metastable Al_xM_y compound, in which significant inhomogeneous strain is caused by the mixture of solute elements. This novel reversion phenomenon is encouraging for obtaining the [am + α-Al] mixture over a wide range of high temperature effective for the formation of Al-based high-strength nanostructured bulk alloys by warm working.

Simultaneous mapping of active DNA demethylation and sister chromatid exchange in single cells

To understand mammalian active DNA demethylation, various methods have been developed to map the genomic distribution of the demethylation intermediates 5-formylcysotine (5fC) and 5-carboxylcytosine (5caC). However, the majority of these methods requires a large number of cells to begin with. In this study, we describe low-input methylase-assisted bisulfite sequencing (liMAB-seq ) and single-cell MAB-seq (scMAB-seq), capable of profiling 5fC and 5caC at genome scale using ∼100 cells and single cells, respectively. liMAB-seq analysis of preimplantation embryos reveals the oxidation of 5mC to 5fC/5caC and the positive correlation between chromatin accessibility and processivity of ten-eleven translocation (TET) enzymes. scMAB-seq captures the cell-to-cell heterogeneity of 5fC and 5caC and reveals the strand-biased distribution of 5fC and 5caC. scMAB-seq also allows the simultaneous high-resolution mapping of sister chromatid exchange (SCE), facilitating the study of this type of genomic rearrangement. Therefore, our study not only establishes new methods for the genomic mapping of active DNA demethylation using limited numbers of cells or single cells but also demonstrates the utilities of the methods in different biological contexts.

Establishing Chromatin Regulatory Landscape during Mouse Preimplantation Development

How the chromatin regulatory landscape in the inner cell mass cells is established from differentially packaged sperm and egg genomes during preimplantation development is unknown. Here, we develop a low-input DNase I sequencing (liDNase-seq) method that allows us to generate maps of DNase I-hypersensitive site (DHS) of mouse preimplantation embryos from 1-cell to morula stage. The DHS landscape is progressively established with a drastic increase at the 8-cell stage. Paternal chromatin accessibility is quickly reprogrammed after fertilization to the level similar to maternal chromatin, while imprinted genes exhibit allelic accessibility bias. We demonstrate that transcription factor Nfya contributes to zygotic genome activation and DHS formation at the 2-cell stage and that Oct4 contributes to the DHSs gained at the 8-cell stage. Our study reveals the dynamic chromatin regulatory landscape during early development and identifies key transcription factors important for DHS establishment in mammalian embryos.