Gene expression profiles in mouse cumulus cells derived from in vitro matured oocytes with and without blastocyst formation

The potential effect of melatonin on in vitro oocyte maturation and embryo development in animals

Melatonin is a hormone mainly secreted by the pineal gland during the circadian cycle, with low levels during the daytime and prominent levels during the night. It is involved in numerous physiological functions including the immune system, circadian rhythm, reproduction, fertilization, and embryo development. In addition, melatonin exerts anti-inflammatory and antioxidant effects inside the body by scavenging reactive oxygen and reactive nitrogen species, increasing antioxidant defenses, and blocking the transcription factors of pro-inflammatory cytokines. Its protective activity has been reported to be effective in various reproductive biotechnological processes, including in vitro maturation (IVM), embryo development, and survival rates. In this comprehensive review, our objective is to summarize and debate the potential mechanism and impact of melatonin on oocyte maturation and embryo development through various developmental routes in different mammalian species.

Induction of mouse totipotent stem cells by a defined chemical cocktail

In mice, only the zygotes and blastomeres from 2-cell embryos are authentic totipotent stem cells (TotiSCs) capable of producing all the differentiated cells in both embryonic and extraembryonic tissues and forming an entire organism1. However, it remains unknown whether and how totipotent stem cells can be established in vitro in the absence of germline cells. Here we demonstrate the induction and long-term maintenance of TotiSCs from mouse pluripotent stem cells using a combination of three small molecules: the retinoic acid analogue TTNPB, 1-azakenpaullone and the kinase blocker WS6. The resulting chemically induced totipotent stem cells (ciTotiSCs), resembled mouse totipotent 2-cell embryo cells at the transcriptome, epigenome and metabolome levels. In addition, ciTotiSCs exhibited bidirectional developmental potentials and were able to produce both embryonic and extraembryonic cells in vitro and in teratoma. Furthermore, following injection into 8-cell embryos, ciTotiSCs contributed to both embryonic and extraembryonic lineages with high efficiency. Our chemical approach to totipotent stem cell induction and maintenance provides a defined in vitro system for manipulating and developing understanding of the totipotent state and the development of multicellular organisms from non-germline cells.

Comprehensive Analysis of Differentially Expressed CircRNAs in the Ovaries of Low- and High-Fertility Sheep

CircRNAs are essential in regulating follicle growth and development and the female reproductive system at multiple levels. However, the molecular mechanism by which circRNAs regulate reproduction in sheep is unclear and requires further exploration. In this study, RNA sequencing was performed to reveal the circRNA expression profiles in the ovaries of Cele black sheep and Hetian sheep during estrus. Analysis of the number of circRNAs in their host genes revealed that 5031 genes could produce 20,835 circRNAs. Among the differentially expressed circRNAs (DEcircRNA), 75 were upregulated, and 105 were downregulated. Functional enrichment analysis showed that the host genes of DEcircRNA were involved in several pathways, including the MAPK and Hippo signaling pathway. In addition, we constructed a subnetwork of competitive endogenous RNA (ceRNA) containing 4 mRNAs, 4 microRNAs (miRNAs), and 10 circRNAs, potentially related to follicle development. Functional circRNAs (e.g., novel_circ_0003851, novel_circ_0015526, novel_circ_0008117) were found to act as ceRNAs for follicle growth and development-related mRNAs (CUEDC1, KPNB1, ZFPM2) by sponging functional miRNAs (miR-29a, miR-29b, miR-17-5p). Finally, through an RNA pull-down assay, oar-miR-125b was selected and confirmed as the target miRNA of novel-circ-0041512. We analyzed the overall expression of circRNAs in sheep ovaries. Further, we explored the potential mechanisms underlying the circRNA functions, providing a theoretical basis for the genetic progress of reproductive traits in sheep.

LGR4 cooperates with PrPc to endow the stemness of colorectal cancer stem cells contributing to tumorigenesis and liver metastasis

Cancer stem cells (CSCs) are a subpopulation of cancer cells that drive tumour progression and metastasis. Anti-CSC strategies represent new targets for cancer therapies. However, CSCs are highly plastic and heterogeneous, making validation and targeting difficult without bona fide markers that define their identity, especially in a clinical setting. Here, we report that a leucine-rich repeat containing G protein-coupled receptor 4 (LGR4) cooperates with CD44 and PrPc; the latter contributes significantly to metastatic capacity and defines the stemness characteristics of colorectal CSCs. CD44⁺PrPc⁺LGR4⁺ cells effectively developed into organoids and, when transplanted, generated orthotopic and metastatic tumours. Importantly, targeting LGR4 and PrPc with lentiviral shRNAs inhibited organoid development and the growth of orthotopic tumours by inhibiting Wnt/β-catenin signalling. Thus, our study offers a novel therapeutic strategy that simultaneously targets CSC stemness and metastatic properties.

Next-Generation Sequencing Reveals Downregulation of the Wnt Signaling Pathway in Human Dysmature Cumulus Cells as a Hallmark for Evaluating Oocyte Quality

Background: Dysmature cumulus cells are lower fertilization rates and abnormalities in embryonic development compared to maturation cumulus cells. Morphological evaluation of cumulus–oocyte complexes (COCs) considered the possibility that differences may also be found in gene expression. Purpose: To identify hallmarks for evaluating oocyte quality by investigating gene expression patterns in human cumulus cells surrounding oocytes. Methods: Cumulus cells were obtained from the cumulus–oocyte complex of infertile women treated with assisted reproductive technology. Based on maturity level, the cumulus cells were classified into two categories, i.e., dysmature cumulus cell (DCC) and maturation cumulus cell. DCCs were subjected to gene expression analysis using next-generation sequencing and compared with COCs that are in the process of maturation as controls. Results: The expression levels of genes involved in the Wnt signal/β-catenin pathway were significantly reduced in DCCs compared with those in control cells. Moreover, the expression levels of genes involved in multiple pathways associated with apoptosis were also significantly reduced compared with those in control cells. Conclusions: DCCs showed significant decreases in apoptosis- and Wnt/β-catenin signaling-associated gene expression. DCCs could be classified by morphological evaluation, and the method described in this study may be useful as an oocyte quality estimation tool.

PPARγ and RhoBTB1 in hypertension

PURPOSE OF REVIEW

This review provides an up-to-date understanding of how peroxisome proliferator activated receptor γ (PPARγ) exerts its cardioprotective effect in the vasculature through its activation of novel PPARγ target genes in endothelium and vascular smooth muscle.

RECENT FINDINGS

In vascular endothelial cells, PPARγ plays a protective role by increasing nitric oxide bioavailability and preventing oxidative stress. RBP7 is a PPARγ target gene enriched in vascular endothelial cells, which is likely to form a positive feedback loop with PPARγ. In vascular smooth muscle cells, PPARγ antagonizes the renin-angiotensin system, maintains vascular integrity, suppresses vasoconstriction, and promotes vasodilation through distinct pathways. Rho-related BTB domain containing protein 1 (RhoBTB1) is a novel PPARγ gene target in vascular smooth muscle cells that mediates the protective effect of PPARγ by serving as a substrate adaptor between the Cullin-3 RING ubiquitin ligase and phosphodiesterase 5, thus restraining its activity through ubiquitination and proteasomal degradation.

SUMMARY

In the vasculature, PPARγ exerts its cardioprotective effect through its transcriptional activity in endothelium and vascular smooth muscle. From the understanding of PPARγ's transcription targets in those pathways, novel hypertension therapy target(s) will emerge.

Genome-wide association study using haplotype alleles for the evaluation of reproductive traits in Nelore cattle

Zebu cattle (Bos taurus indicus) are highly adapted to tropical regions. However, females reach puberty after taurine heifers, which affects the economic efficiency of beef cattle breeding in the tropical regions. The aims of this study were to establish associations between the haplotype alleles of the bovine genome and age at first calving (AFC) in the Nelore cattle, and to identify the genes and quantitative trait loci (QTL) related to this phenotype. A total of 2,273 Nelore cattle (995 males and 1,278 females) genotyped using the Illumina BovineHD BeadChip were used in the current study. The association analysis included females with valid first calving records as well as open heifers. Linkage disequilibrium (LD) analysis among the markers was performed using blocks of 5, 10, and 15 markers, which were determined by sliding windows shifting one marker at a time. Then, the haplotype block size to be used in the association study was chosen based on the highest r² average among the SNPs in the block. The five HapAlleles most strongly associated with the trait (top five) were considered as significant associations. The results of the analysis revealed four genomic regions related to AFC, which overlapped with 20 QTL of the reproductive traits reported previously. Furthermore, there were 19 genes related to reproduction in those regions. In conclusion, the use of haplotypes allowed the detection of chromosomal regions associated with AFC in Nelore cattle, and provided the basis for elucidating the mechanisms underlying this trait.

Enhancement of the efficiency of oocyte vitrification through regulation of histone deacetylase 6 expression

OBJECTIVE

Successful oocyte vitrification (OV) is critical for cryopreservation of the oocytes from female patients with infertility, polycystic ovaries, and gynecologic cancers. Recent evidence suggests that relatively low levels of histone acetylation are critical for maintenance of the maturation capacity of cryopreserved oocytes. However, previous studies have only demonstrated a key role of histone deacetylases (HDAC) 1 and 2 in the cryopreservation of oocytes.

METHODS

In this study, we investigated the role of HDAC6 in these settings. We found that mouse oocytes with low HDAC6 levels decreased survival rate, cleavage rate, and blastocyst rate after OV. Bioinformatics analyses were used to predict HDAC6-targeting microRNAs (miRNAs), while the functional binding of miRNAs to HDAC6 mRNA was evaluated by a dual luciferase reporter assay.

RESULTS

Among all HDAC6-targeting miRNAs, we detected expression of miR-558, miR-527, and miR-762 in mouse oocytes. Specifically, we found that only miR-762 significantly inhibited protein translation of HDAC6 via binding to the 3'-UTR of the HDAC6 mRNA. Transfection of oocytes with HDAC6 or antisense of miR-762 significantly increased the survival rate, the cleavage rate, and blastocyst rate after OV.

CONCLUSION

As a result, our data suggest that induction of HDAC6 levels by miR-762 suppression may improve the current protocol for OV.