Cysteine dioxygenase and taurine are essential for embryo implantation by involving in E2-ERα and P4-PR signaling in mouse

Methionine in embryonic development: metabolism, redox homeostasis, epigenetic modification and signaling pathway

Methionine, an essential sulfur-containing amino acid, plays a critical role in methyl metabolism, folate metabolism, polyamine synthesis, redox homeostasis maintenance, epigenetic modification and signaling pathway regulation, particularly during embryonic development. Animal and human studies have increasingly documented that methionine deficiency or excess can negatively impact metabolic processes, translation, epigenetics, and signaling pathways, with ultimate detrimental effects on pregnancy outcomes. However, the underlying mechanisms by which methionine precisely regulates epigenetic modifications and affects signaling pathways remain to be elucidated. In this review, we discuss methionine and the metabolism of its metabolites, the influence of folate-mediated carbon metabolism, redox reactions, DNA and RNA methylation, and histone modifications, as well as the mammalian rapamycin complex and silent information regulator 1-MYC signaling pathway. This review also summarizes our present understanding of the contribution of methionine to these processes, and current nutritional and pharmaceutical strategies for the prevention and treatment of developmental defects in embryos.

Taurine is essential for mouse uterine luminal fluid resorption during implantation window via the SCNN1A and AQP8 signaling†

Uterine fluid homeostasis during peri-implantation is crucial for successful embryo implantation. Taurine (Tau) plays a crucial role in regulating osmotic pressure and ion transport. However, the precise mechanisms underlying Tau-mediated regulation of uterine fluid homeostasis during peri-implantation in mice remain unclear. In this study, we generated a Tau-deficient mouse model by administering Tau-free diet to Csad knockout (Csad-/-) mice to block endogenous Tau synthesis and exogenous Tau absorption (Csad-/--Tau free). Our findings demonstrated that Csad-/--Tau free mice with diminished level of Tau exhibited decreased rates of embryo implantation and impaired fertility. Further analysis revealed that the expression of Scnn1a was down-regulated during the implantation window, while Aqp8 was upregulated in Csad-/--Tau free mice, leading to uterine luminal fluid retention and defects in luminal closure, resulting in failed embryo implantation. Additionally, it was also found that E2 inhibited uterine Csad expression and Tau synthesis, while P4 promoted them. Therefore, our findings suggest that ovarian steroid hormones regulate Csad expression and Tau synthesis, thereby affecting release and resorption of uterine luminal fluid, ultimately impacting embryo implantation success.

Improving pregnancy outcomes in patients with recurrent implantation failure: The power of RNA-seq-based endometrial receptivity testing

To evaluate whether RNA-seq-based endometrial receptivity testing (rsERT) can improve pregnancy outcomes in personalized frozen-thawed embryo transfer (pFET) during hormone replacement therapy (HRT) cycles among patients with recurrent implantation failure (RIF). We conducted a retrospective cohort study involving 98 RIF patients undergoing HRT for FET. The experimental group consisted of 58 patients who underwent pFET after rsERT, while the control group included 40 patients who refused rsERT and underwent conventional ET. We recorded and examined the subsequent pregnancy outcomes from all cycles. The results of rsERT revealed that 67.24% of the experimental group were out of the "window of implantation" (WOI), with all cases showing a delay. The HCG-positive rate, implantation rate, and clinical pregnancy rate (CPR) in the experimental group were significantly higher than those in the control group, at 75.86% versus 50.00% (P = .030), 56.38% versus 31.43% (P = .002), and 68.97% versus 47.50% (P = .033), respectively. Our study demonstrated that utilizing rsERT technology to guide pFET in HRT cycles significantly enhances implantation and CPRs in RIF patients. Importantly, our findings confirm the effectiveness of rsERT technology and establish a scientific rationale for personalized reproductive medical interventions.

Cloning, bioinformatics analysis and expression of the cysteine dioxygenase type 1 (CDO1) gene in domestic yak

Introduction

The CDO1 gene is an important gene in the taurine synthesis pathway and has been observed to have high expression in ovaries of female mammals. This study aims to explore the conservation of CDO1 gene in domestic yaks, as well as to examine the fundamental characteristics of CDO1 gene and its expression in female yaks.

Methods

Ovarian samples were collected from yaks in the follicular phase, luteal phase and gestation period in this experiment, and their total RNA and protein were extracted. Then Polymerase Chain Reaction (PCR) and bioinformatics online software were used to clone and analyze the CDO1 gene. The relative expression of CDO1 in yak ovaries was detected by Quantitative Real-time PCR (RT-qPCR) and Western blotting. The distribution and localization of CDO1 protein in ovary were detected by immunohistochemistry.

Results

We have successfully cloned the coding region of CDO1 gene in yak. The results showed that the CDS region of CDO1 gene was 603 bp, encoding 200 amino acids, and was a relatively stable hydrophilic protein. CDO1 is relatively conservative in species evolution. The protein encoded by CDO1 gene does not have a signaling peptide or a transmembrane structure. It is a protein that is not involved in transmembrane transport and is mainly located in the cytoplasm. The secondary structure of the protein is dominated by the random coil. CDO1 is estimated to interact with 10 proteins. The results of RT-qPCR and Western blotting showed that the CDO1 gene exhibited the highest expression in the ovary during the luteal phase and the lowest expression in the ovary during the follicular phase (P < 0.01). The results of immunohistochemistry showed that CDO1 was mainly expressed in granular cells, theca cells and lutein cells of ovarian tissue.

Conclusion

These results suggest that the CDO1 gene has undergone minimal evolutionary changes during the course of animal evolution. The results provide a reference for further investigation of the function of CDO1 gene in reproduction and production in yaks.

Taurine Alleviates Experimental Colitis by Enhancing Intestinal Barrier Function and Inhibiting Inflammatory Response through TLR4/NF-κB Signaling

Taurine (Tau) is a semiessential amino acid in mammals with preventive and therapeutic effects on several intestinal disorders. However, the exact function of taurine in ulcerative colitis (UC) is still largely unclear. In this study, we used two taurine-deficient mouse models (CSAD-/- and TauT-/- mice) to explore the influence of taurine on the progression of UC in both dextran sulfate sodium (DSS)-induced colitis and LPS-stimulated Caco-2 cells. We found that cysteine sulfinic acid decarboxylase (CSAD) and taurine transporter (TauT) expressions and taurine levels were markedly reduced in colonic tissues of mice treated with DSS. The CSAD and TauT knockouts exacerbated DSS-induced clinical symptoms and pathological damage and aggravated the intestinal barrier dysfunction and the colonic mucosal inflammatory response. Conversely, taurine pretreatment enhanced the intestinal barrier functions by increasing goblet cells and upregulating tight junction protein expression. Importantly, taurine bound with TLR4 and inhibited the TLR4/NF-κB pathway, ultimately reducing proinflammatory factors (TNF-α and IL-6) and oxidative stress. Our findings highlight the essential role of taurine in maintaining the intestinal barrier integrity and inhibiting intestinal inflammation, indicating that taurine is a promising supplement for colitis treatment.

Taurine promotes insulin synthesis by enhancing Isl-1 expression through miR-7a/RAF1/ERK1/2 pathway

It has been well established that the circulating taurine affects the insulin synthesis in pancreatic islet β-cells, whereas miR-7a and LIM-homeodomain transcription factor Isl-1 are important intracellular factors regulating insulin transcription and synthesis. However, it still remains unknown whether taurine regulates insulin synthesis by affecting miR-7a and/or Isl-1 expressions in mouse pancreatic islet β-cells. The present study was thus proposed to identify the effects of taurine on the expressions of miR-7a and/or Isl-1 and their relations to insulin synthesis in mouse pancreatic islet β-cells by using miR-7a2 knockout (KO) and taurine transporter (TauT) KO mouse models and the related in vitro experiments. The results demonstrated that taurine supplement significantly decreased the pancreas miR-7a expression, but sharply upregulated the pancreas Isl-1 and insulin expressions, and serum insulin levels. However, the enhanced effects of taurine on Isl-1 expression and insulin synthesis were mitigated in the TauT KO and miR-7a2 KO mice. In addition, our results confirmed that taurine markedly increased pancreas RAF1 and ERK1/2 expressions. Collectively, the present study firstly demonstrates that taurine regulates insulin synthesis through TauT/miR-7a/RAF1/ERK1/2/Isl-1 signaling pathway, which are crucial for our understanding the mechanisms of taurine affecting insulin synthesis, and also potential for establishing the therapeutic strategies for diabetes and the diseases related to metabolism.

Identification of a novel enzyme and the regulation of key enzymes in mammalian taurine synthesis

Taurine has many pharmacological roles on various tissues. The maintenance of abundant taurine content in the mammalian body through endogenous synthesis, in addition to exogenous intake, is the essential factor for morphological and functional maintenances in most tissues. The synthesis of taurine from sulfur-containing amino acids is influenced by various factors. Previous literature findings indicate the influence of the intake of proteins and sulfur-containing amino acids on the activity of the rate-limiting enzymes cysteine dioxygenase and cysteine sulfinate decarboxylase. In addition, the regulation of the activity and expression of taurine-synthesis enzymes by hormones, bile acids, and inflammatory cytokines through nuclear receptors have been reported in liver and reproductive tissues. Furthermore, flavin-containing monooxygenase subtype 1 was recently identified as the taurine-synthesis enzyme that converts hypotaurine to taurine. This review introduces the novel taurine synthesis enzyme and the nuclear receptor-associated regulation of key enzymes in taurine synthesis.