Sperm penetration at the maturing metaphase I stage can trigger oocyte activation in a mouse model.

Research Question: Can spermatozoa penetrate maturing metaphase I (MI) oocytes, and render subsequent development following conventional IVF in a mouse model?

Design: ICR mice were used in this study. Metaphase II (MII) cumulus-oocyte complexes (COC) harvested 15 h after injection of human chorionic gonadotrophin (HCG) were used for IVF as the control group (Group 1). In the treatment group (Group 2), maturing MI COC harvested 7 h after HCG injection were used for IVF.

The IMPDH cytoophidium couples metabolism and fetal development in mice.

The cytoophidium is an evolutionarily conserved subcellular structure formed by filamentous polymers of metabolic enzymes. In vertebrates, inosine monophosphate dehydrogenase (IMPDH), which catalyses the rate-limiting step in guanosine triphosphate (GTP) biosynthesis, is one of the best-known cytoophidium-forming enzymes. Formation of the cytoophidium has been proposed to alleviate the inhibition of IMPDH, thereby facilitating GTP production to support the rapid proliferation of certain cell types such as lymphocytes, cancer cells and pluripotent stem cells (PSCs).

ZSCAN4 interacts with PARP1 to promote DNA repair in mouse embryonic stem cells.

Background: In eukaryotic cells, DNA double strand breaks (DSB) are primarily repaired by canonical non-homologous end joining (c-NHEJ), homologous recombination (HR) and alternative NHEJ (alt-NHEJ). Zinc finger and SCAN domain containing 4 (ZSCAN4), sporadically expressed in 1-5% mouse embryonic stem cells (mESCs), is known to regulate genome stability by promoting HR.

Results: Here we show that ZSCAN4 promotes DNA repair by acting with Poly (ADP-ribose) polymerase 1 (PARP1), which is a key member of the alt-NHEJ pathway.

Podocalyxin-Like Protein 1 Regulates Pluripotency through the Cholesterol Biosynthesis Pathway.

Deciphering signaling mechanisms critical for the extended pluripotent stem cell (EPSC) state and primed pluripotency is necessary for understanding embryonic development. Here, a membrane protein, podocalyxin-like protein 1 (PODXL) as being essential for extended and primed pluripotency, is identified. Alteration of PODXL expression levels affects self-renewal, protein expression of c-MYC and telomerase, and induced pluripotent stem cell (iPSC) and EPSC colony formation.

Survival Motor Neuron Enhances Pluripotent Gene Expression and Facilitates Cell Reprogramming.

Survival motor neuron (SMN) plays important roles in snRNP assembly and mRNA splicing. Deficiency of SMN causes spinal muscular atrophy (SMA), a leading genetic disease causing childhood mortality. Previous studies have shown that SMN regulates stem cell self-renewal and pluripotency in and mouse and is abundantly expressed in mouse embryonic stem cells.

Molecular crowding facilitates bundling of IMPDH polymers and cytoophidium formation.

The cytoophidium is a unique type of membraneless compartment comprising of filamentous protein polymers. Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step of de novo GTP biosynthesis and plays critical roles in active cell metabolism. However, the molecular regulation of cytoophidium formation is poorly understood.

Effects of Recloning on the Telomere Lengths of Mouse Nuclear Transfer-Derived Embryonic Stem Cells.

Haploinsufficiency of genes that participate in telomere elongation and maintenance processes, such as telomerase RNA component () and telomere reverse transcriptase (), often leads to premature aging-related diseases such as dyskeratosis congenita and aplastic anemia. Previously, we reported that when mouse tail tip fibroblasts (TTFs) were used as donor cells for somatic cell nuclear transfer (SCNT, also known as cloning), the derivative embryonic stem cells (ntESCs) had elongated telomeres. In the present work, we are interested to know if an additional round of SCNT, or recloning, could lead to further elongation of telomeres.

Cruciform DNA Structures Act as Legible Templates for Accelerating Homologous Recombination in Transgenic Animals.

Inverted repeat (IR) DNA sequences compose cruciform structures. Some genetic disorders are the result of genome inversion or translocation by cruciform DNA structures. The present study examined whether exogenous DNA integration into the chromosomes of transgenic animals was related to cruciform DNA structures.

CTPS forms the cytoophidium in zebrafish.

Cytidine triphosphate synthase (CTPS) catalyzes the rate-limiting step of de novo CTP biosynthesis. An intracellular structure of CTPS, the cytoophidium, has been found in many organisms including prokaryotes and eukaryotes. Formation of the cytoophidium has been suggested to regulate the activity and stability of CTPS and may participate in certain physiological events.

IMPDH forms the cytoophidium in zebrafish.

Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step in de novo guanine nucleotide biosynthesis. Its activity is negatively regulated by the binding of GTP. IMPDH can form a membraneless subcellular structure termed the cytoophidium in response to certain changes in the metabolic status of the cell.

CTPS and IMPDH form cytoophidia in developmental thymocytes.

The cytoophidium, a filamentous structure formed by metabolic enzymes, has emerged as a novel regulatory machinery for certain proteins. The rate-limiting enzymes of de novo CTP and GTP synthesis, cytidine triphosphate synthase (CTPS) and inosine monophosphate dehydrogenase (IMPDH), are the most characterized cytoophidium-forming enzymes in mammalian models. Although the assembly of CTPS cytoophidia has been demonstrated in various organisms including multiple human cancers, a systemic survey for the presence of CTPS cytoophidia in mammalian tissues in normal physiological conditions has not yet been reported.

STAT3 Is an Upstream Regulator of in the Maternal-To-Zygotic Transition of Mouse Embryos.

The maternal-to-zygotic transition (MZT), which controls maternal signaling to synthesize zygotic gene products, promotes the preimplantation development of mouse zygotes to the two-cell stage. Our previous study reported that mouse granzyme g (Gzmg), a serine-type protease, is required for the MZT. In this study, we further identified the maternal factors that regulate the promoter activity in the zygote to the two-cell stage of mouse embryos.

Effects of Survival Motor Neuron Protein on Germ Cell Development in Mouse and Human.

Survival motor neuron (SMN) is ubiquitously expressed in many cell types and its encoding gene, survival motor neuron 1 gene (SMN1), is highly conserved in various species. SMN is involved in the assembly of RNA spliceosomes, which are important for pre-mRNA splicing. A severe neurogenic disease, spinal muscular atrophy (SMA), is caused by the loss or mutation of SMN1 that specifically occurred in humans.

SNAP29 mediates the assembly of histidine-induced CTP synthase filaments in proximity to the cytokeratin network.

Under metabolic stress, cellular components can assemble into distinct membraneless organelles for adaptation. One such example is cytidine 5'-triphosphate synthase (CTPS, for which there are CTPS1 and CTPS2 forms in mammals), which forms filamentous structures under glutamine deprivation. We have previously demonstrated that histidine (His)-mediated methylation regulates the formation of CTPS filaments to suppress enzymatic activity and preserve the CTPS protein under glutamine deprivation, which promotes cancer cell growth after stress alleviation.

Survival Motor Neuron Protein Participates in Mouse Germ Cell Development and Spermatogonium Maintenance.

The defective human survival motor neuron 1 (SMN1) gene leads to spinal muscular atrophy (SMA), the most common genetic cause of infant mortality. We previously reported that loss of SMN results in rapid differentiation of Drosophila germline stem cells and mouse embryonic stem cells (ESCs), indicating that SMN also plays important roles in germ cell development and stem cell biology. Here, we show that in healthy mice, SMN is highly expressed in the gonadal tissues, prepubertal spermatogonia, and adult spermatocytes, whereas low SMN expression is found in differentiated spermatid and sperm.

Compromised Chondrocyte Differentiation Capacity in TERC Knockout Mouse Embryonic Stem Cells Derived by Somatic Cell Nuclear Transfer.

Mammalian telomere lengths are primarily regulated by telomerase, consisting of a reverse transcriptase protein (TERT) and an RNA subunit (). We previously reported the generation of mouse and embryonic stem cells (ntESCs) by somatic cell nuclear transfer. In the present work, we investigated the germ layer development competence of , and wild-type () ntESCs.

Combining orthogonal CRISPR and CRISPRi systems for genome engineering and metabolic pathway modulation in Escherichia coli.

CRISPR utilizing Cas9 from Streptococcus pyogenes (SpCas9) and CRISPR interference (CRISPRi) employing catalytically inactive SpCas9 (SpdCas9) have gained popularity for Escherichia coli engineering. To integrate the SpdCas9-based CRISPRi module using CRISPR while avoiding mutual interference between SpCas9/SpdCas9 and their cognate single-guide RNA (sgRNA), this study aimed at exploring an alternative Cas nuclease orthogonal to SpCas9. We compared several Cas9 variants from different microorganisms such as Staphylococcus aureus (SaCas9) and Streptococcus thermophilius CRISPR1 (St1Cas9) as well as Cas12a derived from Francisella novicida (FnCas12a).

Histidine-Dependent Protein Methylation Is Required for Compartmentalization of CTP Synthase.

CTP synthase (CTPS) forms compartmentalized filaments in response to substrate availability and environmental nutrient status. However, the physiological role of filaments and mechanisms for filament assembly are not well understood. Here, we provide evidence that CTPS forms filaments in response to histidine influx during glutamine starvation.

Interfilament interaction between IMPDH and CTPS cytoophidia.

Inosine monophosphate dehydrogenase (IMPDH) and cytidine triphosphate synthase (CTPS) are two metabolic enzymes that perform rate-limiting steps in the de novo synthesis of purine and pyrimidine nucleotides, respectively. It has been shown that IMPDH and CTPS can comprise a filamentous macrostructure termed the cytoophidium, which may play a role in regulation of their catalytic activity. Although these two proteins may colocalise in the same cytoophidium, how they associate with one another is still elusive.

IMP/GTP balance modulates cytoophidium assembly and IMPDH activity.

Background: Inosine monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in de novo GTP biosynthesis, plays an important role in cell metabolism and proliferation. It has been demonstrated that IMPDH can aggregate into a macrostructure, termed the cytoophidium, in mammalian cells under a variety of conditions. However, the regulation and function of the cytoophidium are still elusive.

CTP synthase forms the cytoophidium in human hepatocellular carcinoma.

CTP synthase (CTPS) can aggregate into an intracellular macrostructure, the cytoophidium, in various organisms including human cells. Previous studies have shown that assembly of human CTPS cytoophidia may be correlated with the cellular metabolic status, and is able to promote the activity of CTPS. A correlation between the cytoophidium and cancer metabolism has been proposed but not yet been revealed.

Combining CRISPR and CRISPRi Systems for Metabolic Engineering of E. coli and 1,4-BDO Biosynthesis.

Biosynthesis of 1,4-butanediol (1,4-BDO) in E. coli requires an artificial pathway that involves six genes and time-consuming, iterative genome engineering. CRISPR is an effective gene editing tool, while CRISPR interference (CRISPRi) is repurposed for programmable gene suppression.

BMP8A sustains spermatogenesis by activating both SMAD1/5/8 and SMAD2/3 in spermatogonia.

Mutation in either of the genes encoding bone morphogenetic protein (BMP) 8A or 8B ( or ) causes postnatal depletion of spermatogonia in mice. We found that , but not , was expressed predominantly in the neonatal mouse spermatogonia. Although most BMPs induce activation of SMADs 1, 5, and 8 (SMAD1/5/8), but not SMADs 2 and 3 (SMAD2/3), we found that BMP8A induced signaling through both sets of transcription factors.