Arginine Regulates Zygotic Genome Activation in Porcine Embryos through Promoting Polyamine Synthesis☆

Background:Arginine has a positive effect on preimplantation development in pigs. However, the exact mechanism by which arginine promotes embryonic development to the blastocyst stage is not undefined. Here, single-cell RNA-sequencing technology was applied to porcine in vivo pre-implantation embryos from zygote to morula to determine transcription patterns of arginine metabolism-related genes during preimplantation embryonic development.Results:Transcriptome sequencing showed that arginine metabolism-related genes clearly changed from the 2-cell stage to the 4-cell stage, where zygotic genome activation (ZGA) occurred in porcine embryos. Further analysis of the correlation between arginine metabolism and ZGA shows that arginine metabolism-related genes are significantly correlated with key ZGA genes such as ZSCAN4, DPPA2 and EIF1A, indicating that arginine metabolism may be an indicator of porcine ZGA. To explore the correlation between arginine metabolism and ZGA, embryos cultured in the medium that removes all the amino acids, proteins and pyruvate in the PZM3 medium were employed to generate the ZGA blocked embryo model. The 4-cell arrest rate significantly increased at 72 h after activation, indicating impeded embryonic development. Meanwhile, results of immunofluorescent staining showed that the expression of SIRT1 protein during ZGA was significantly inhibited. Results of quantitative PCR showed that the expression of zygotic genes (ZSCAN4, DPPA2 and EIF1A) was significantly decreased. The above results indicate that the ZGA blocked embryo model was successfully established. Adding of arginine recovered embryonic development, SIRT1 and zygotic genes expression levels and initiated the ZGA. In addition, ROS content significantly increased when ZGA was blocked, and the GSH, ATP and lipid droplet content significantly decreased. After the addition of arginine in the block group, the ROS content significantly decreased, and the GSH, ATP and lipid droplet content significantly increased. Moreover, the ornithine decarboxylase (ODC) inhibitor difluoromethylornithine (DFMO) and arginine were added to the block group at the same time, and the effect of arginine was found to be inhibited. Conclusions: Arginine is essential for ZGA in porcine embryos. Arginine contributes to porcine ZGA by promoting polyamine synthesis in porcine embryos.

Arginine and Arginases Modulate Metabolism, Tumor Microenvironment and Prostate Cancer Progression

Arginine availability and activation of arginine-related pathways at cancer sites have profound effects on the tumor microenvironment, far beyond their well-known role in the hepatic urea cycle. Arginine metabolism impacts not only malignant cells but also the surrounding immune cells behavior, modulating growth, survival, and immunosurveillance mechanisms, either through an arginase-mediated effect on polyamines and proline synthesis, or by the arginine/nitric oxide pathway in tumor cells, antitumor T-cells, myeloid-derived suppressor cells, and macrophages. This review presents evidence concerning the impact of arginine metabolism and arginase activity in the prostate cancer microenvironment, highlighting the recent advances in immunotherapy, which might be relevant for prostate cancer. Even though further research is required, arginine deprivation may represent a novel antimetabolite strategy for the treatment of arginine-dependent prostate cancer.

The Role of Arginine Metabolism in Oral Tongue Squamous Cell Carcinoma

Early diagnosis and treatment do not prevent the high morbidity and poor prognosis of oral tongue squamous cell carcinoma (TSCC). Earlier studies have shown that ARG1 signaling is deregulated in TSCC. Here, we investigated the complexity of ARG1 metabolism in this cancer subsite to appreciate the therapeutic potential of this potential biological vulnerability. Various functional studies show that ARG1 overexpression in oral cancer cells inhibits cell proliferation and invasion compared with controls. Further, RNA-sequencing revealed numerous differentially expressed genes (DEGs) and associated networks were dysregulated by ARG1 overexpression, including hypoxia-inducible factor (HIFα) signaling, the natural killer cell signaling pathway and interferon signaling. Our work provides a foundation for understanding the mechanism of action of disrupted arginine metabolism in oral tongue squamous cell carcinoma. This may impact the community for developing further therapeutic approaches.

Dysregulated Arginine Metabolism in Young Patients with Chronic Persistent Asthma and in Human Bronchial Epithelial Cells

Background: Recent metabolomics studies have found circulatory metabolism alterations in patients with asthma, indicating that altered metabolites played a significant role in asthma. However, the regulatory mechanisms in asthma, especially in young chronic persistent asthma remain underexplored. Methods: In this study, a prospective cohort of 162 patients diagnosed of asthma admitted to the First Affiliated Hospital of Xi’an Jiaotong University from January 2018 to December 2019 was used to perform a nested case-control study. Among them, we included 30 patients with chronic persistent asthma between 20 to 35 years old; 30 health control with evenly distributed age and sex were then recruited. Nontargeted metabolomics was applied to identify serum metabolic profiles and altered metabolic pathways. Results: In vitro, human bronchial epithelial cells (HBECs) line BEAS-2B with the addition of L-citrulline and/or asymmetric dimethylarginine (ADMA) model was utilized and the concentrations of nitric oxide (NO) metabolites were tested to evaluate the therapeutic potential of L-citrulline. The young patients with chronic persistent asthma displayed dysregulated serum metabolic profiles, especially enriched in arginine metabolism. The ratio of L-citrulline to ornithine is associated with blood eosinophil count. In vitro, adding L-citrulline could reverse ADMA-mediated reduction of NOx at lower L-arginine concentration (25 μM), but was ineffective in the higher L-arginine concentration (100 μM) media. Conclusions: The arginine metabolism balance is of vital importance during the pathogenesis and progression of chronic asthma. L-citrulline could be a powerful approach to restore airway NO production, potentially exhibiting therapeutic benefits among young patients with chronic asthma.

Evaluation of Anti-Inflammatory Effects of Celery Leaf and Stem Extracts in LPS-Induced RAW 264.7 Cells Using Nitric Oxide Assay and LC-MS Based Metabolomics

The present work demonstrated and compared the anti-inflammatory effects of celery leaf (CLE) and stem (CSE) extracts. LC-MS-based metabolomics were an effective approach to achieve the biomarker identification and pathway elucidation associated with the reduction in inflammatory responses. The celery extracts suppressed LPS-induced NO production in RAW 264.7 cells, and CLE was five times more effective than CSE. Distinct differences were revealed between the control and celery-treated samples among the 24 characteristic metabolites that were identified. In celery-treated LPS cells, reversals of intracellular (citrulline, proline, creatine) and extracellular (citrulline, lysine) metabolites revealed that the therapeutic outcomes were closely linked to arginine metabolism. Reversals of metabolites when treated with CLE (aspartate, proline) indicated targeted effects on the TCA and urea cycles, while, in the case of CSE (histidine, glucose), the glycolysis and the pentose phosphate pathways were implicated. Subsequently, apigenin and bergapten in CLE were identified as potential biomarkers mediating the anti-inflammatory response.

Arginine metabolism and nitric oxide turnover in the ZSF1 animal model for heart failure with preserved ejection fraction

Endothelial dysfunction and altered nitric oxide (NO) metabolism are considered causal factors in heart failure with preserved ejection fraction (HFpEF). NO synthase activity depends on the availability of arginine and its derivatives. Thus, we analyzed arginine, associated metabolites, arginine-metabolizing enzymes and NO turnover in 20-week-old female healthy lean (L-ZSF1) and obese ZSF1 rats (O-ZSF1) with HFpEF. Serum, urine and lysates of liver, kidney and heart were analyzed. There were significantly lower lysine (− 28%), arginine (− 31%), homoarginine (− 72%) and nitrite (− 32%) levels in serum of O-ZSF1 rats. Ornithine (+ 60%) and citrulline (+ 20%) levels were higher. Similar results were found in the heart. Expression of arginine consuming enzymes in liver and kidney was unchanged. Instead, we observed a 5.8-fold higher arginase 1 expression, presumably of granulocyte origin, in serum and > fourfold increased cardiac macrophage invasion in O-ZSF1. We conclude that inflammatory cells in blood and heart consume arginine and probably homoarginine via arginase 1 and inducible NO synthase and release ornithine and citrulline. In combination with evidence for decreased NO turnover in O-ZSF1 rats, we assume lower arginine bioavailability to endothelial NO synthase.

Lactiplantibacillus plantarum Reduced Renal Calcium Oxalate Stones by Regulating Arginine Metabolism in Gut Microbiota

Renal calcium oxalate (CaOx) stones are a common kidney disease. There are few methods for reducing the formation of these stones. However, the potential of probiotics for reducing renal stones has received increasing interest. We previously isolated a strain of Lactiplantibacillus plantarum N-1 from traditional cheese in China. This study aimed to investigate the effects of N-1 on renal CaOx crystal deposition. Thirty rats were randomly allocated to three groups: control group (ddH2O by gavage), model group [ddH2O by gavage and 1% ethylene glycol (EG) in drinking water], and Lactiplantibacillus group (N-1 by gavage and 1% EG in drinking water). After 4 weeks, compared with the model group, the group treated with N-1 exhibited significantly reduced renal crystals (P < 0.05). In the ileum and caecum, the relative abundances of Lactobacillus and Eubacterium ventriosum were higher in the control group, and those of Ruminococcaceae UCG 007 and Rikenellaceae RC9 were higher in the N-1-supplemented group. In contrast, the relative abundances of Staphylococcus, Corynebacterium 1, Jeotgalicoccus, Psychrobacter, and Aerococcus were higher in the model group. We also predicted that the arginase level would be higher in the ileal microbiota of the model group than in the N-1-supplemented group with PICRUSt2. The arginase activity was higher, while the level of arginine was lower in the ileal contents of the model group than in the N-1-supplemented group. The arginine level in the blood was also higher in the N-1-supplemented group than in the model group. In vitro studies showed that exposure to arginine could reduce CaOx crystal adhesion to renal epithelial HK-2 cells. Our findings highlighted the important role of N-1 in reducing renal CaOx crystals by regulating arginine metabolism in the gut microbiota. Probiotics containing L. plantarum N-1 may be potential therapies for preventing renal CaOx stones.

Changes of L-Arginine Metabolism in Rat`S Colon Mucosa Under the Conditions of COX/LOX Inhibition and Acute Stress Action

Introduction. L-arginine is a semi-essential amino acid and a precursor of many biologically active compounds. Polyamines and NO produced from L-arginine take part in the regulation of biochemical processes in colon mucosa. Emotional stress, nonsteroidal anti-inflammatory drugs (NSAIDs) and their combined action can change the activity of L-arginine metabolizing enzymes. The aim of this study was to investigate the single action of NSAIDs with different mechanisms of action and their combination with acute stress on L-arginine metabolism in colon mucosa of rats. Methods. Animals were divided into 8 groups: control group (1), administration of nonselective, COX-2 selective and dual COX-2/5-LOX inhibitors (groups 2-4), acute stress group (5), administration of same NSAIDs as in groups 2-4 under the conditions of acute stress (groups 6-8). The activity of iNOS, cNOS, arginase, concentration of L-arginine, nitrite and nitrate was measured in colon mucosa. Results. Nonselective COX inhibition by naproxen caused the increase in iNOS and decrease in cNOS activity in colon mucosa. Both COX-2 (celecoxib) and dual COX-2/5-LOX (2A5DHT) inhibitors enhanced cNOS and arginase acting in combination with acute stress. The concentration of L-arginine remained unchanged in most of the groups, but combination of dual COX-2/5-LOX inhibitor and acute stress raised this parameter.