Low Levels Of Methionine Research Articles

Sulfur metabolism under stress: Oxidized glutathione inhibits methionine biosynthesis by destabilizing the enzyme cystathionine γ-synthase.

Cysteine is the precursor for the biosynthesis of glutathione, a key stress-protective metabolite, and methionine, which is imperative for cell growth and protein synthesis. The exact mechanism that governs the routing of cysteine toward glutathione or methionine during stresses remains unclear. Our study reveals that under oxidative stress, methionine and glutathione compete for cysteine and that the increased oxidized glutathione (GSSG) levels under stress hinder methionine biosynthesis. Moreover, we find that inhibition occurs as GSSG binds to and accelerates the degradation of cystathionine γ-synthase, a key enzyme in the methionine synthesis pathway. Consequently, this leads to a reduction in the flux toward methionine-derived metabolites and redirects cysteine utilization toward glutathione, thereby enhancing plant protection. Our study suggests a novel regulatory feedback loop involving glutathione, methionine, and cysteine, shedding light on the plant stress response and the adaptive rerouting of cysteine. These findings offer new insights into the intricate balance of growth and protection in plants and its impact on their nutritional value due to low methionine levels under stress.

Improvement of glucose metabolism in middle-aged mice on a high-fat diet by whole-grain highland barley is related to low methionine levels

Methionine restriction (MR) is an effective dietary strategy to regulate energy metabolism and alleviate oxidative stress and inflammation in the body, especially in the middle-aged and elderly population. However, the high methionine content of meat products makes this dietary strategy impossible to combine with protein supplementation and MR. Highland barley (HB), a low-methionine cereal, not only provides the body with protein but also has improved glucose metabolism and antioxidant and anti-inflammatory properties. Therefore, this study evaluated the feasibility of HB as a source of methionine-restricted dietary protein and the potential mechanisms. Middle-aged C57BL/6J mice were fed a control diet (CON), a high-fat diet (HFD), a whole-grain HB high-fat diet (HBHF), or a HBHF + methionine diet (HBHFmet) for 25 weeks. The results showed that the HBHF could keep the body weight, fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), blood lipids, inflammation, and oxidative stress of HFD mice at normal levels. Compared with the HFD groups, HBHF inhibited pancreatic cell apoptosis and improved insulin secretion while improving hepatic and skeletal muscle glucose metabolism. However, these efficacies were attenuated in HBHFmet group mice. These findings suggest that HBHF has an MR strategy.

The Association of the Essential Amino Acids Lysine, Methionine, and Threonine with Clinical Outcomes in Patients at Nutritional Risk: Secondary Analysis of a Randomized Clinical Trial.

Lysine, methionine, and threonine are essential amino acids with vital functions for muscle and connective tissue health, metabolic balance, and the immune system. During illness, the demand for these amino acids typically increases, which puts patients at risk for deficiencies with harmful clinical consequences. In a secondary analysis of the Effect of Early Nutritional Support on Frailty, Functional Outcomes, and Recovery of Malnourished Medical Inpatients Trial (EFFORT), which compared individualized nutritional support to usual care nutrition in patients at nutritional risk, we investigated the prognostic impact of the lysine, methionine, and threonine metabolism. We had complete clinical and amino acid data in 237 patients, 58 of whom reached the primary endpoint of death at 30 days. In a model adjusted for comorbidities, sex, nutritional risk, and trial intervention, low plasma methionine levels were associated with 30-day mortality (adjusted HR 1.98 [95% CI 1.16 to 3.36], p = 0.01) and with a decline in functional status (adjusted OR 2.06 [95% CI 1.06 to 4.01], p = 0.03). The results for lysine and threonine did not show statistically significant differences regarding clinical outcomes. These findings suggest that low levels of methionine may be critical during hospitalization among patients at nutritional risk. Further studies should investigate the effect of supplementation of methionine in this patient group to improve outcomes.

Case presentation: a severe case of cobalamin c deficiency presenting with nephrotic syndrome, malignant hypertension and hemolytic anemia

BackgroundThe etiology of nephrotic syndrome can vary, with underlying metabolic diseases being a potential factor. Cobalamin C (cblC) defect is an autosomal recessive inborn error of metabolism caused by mutations in the MMACHC gene, resulting in impaired vitamin B12 processing. While cblC defect typically manifests with hematological and neurological symptoms, renal involvement is increasingly recognized but remains rare.Case PresentationWe describe a 7-month-old male patient presenting with fatigue and edema. His initial laboratory findings showed anemia, thrombocytopenia, hypoalbuminemia and proteinuria. Further examinations reveals hemolysis in peripheral blood smear. During his follow up respiratory distress due to pleural effusion in the right hemithorax was noticed. And fluid leakage to the third spaces supported a diagnosis of nephrotic syndrome. The patient’s condition deteriorated, leading to intensive care admission due to, hypertensive crisis, and respiratory distress. High total plasma homocysteine and low methionine levels raised suspicion of cobalamin metabolism disorders. Genetic testing confirmed biallelic MMACHC gene mutations, establishing the diagnosis of cblC defect. Treatment with hydroxycobalamin, folic acid, and betaine led to remarkable clinical improvement.Discussion/ConclusionThis case underscores the significance of recognizing metabolic disorders like cblC defect in atypical presentations of nephrotic syndrome. Early diagnosis and comprehensive management are vital to prevent irreversible renal damage. While cblC defects are more commonly associated with atypical hemolytic uremic syndrome, this case highlights the importance of considering cobalamin defects in the differential diagnosis of nephrotic syndrome, especially when associated with accompanying findings such as hemolysis. Our case, which has one of the highest homocysteine levels reported in the literature, emphasizes this situation again.

Novel compound heterozygous mutations of MTHFR Gene in a Chinese family with homocystinuria due to MTHFR deficiency

BackgroundHomocystinuria due to methylenetetrahydrofolate reductase (MTHFR) deficiency is a rare autosomal recessive disorder. The purpose of this study is to expand the mutation site of the MTHFR gene and provide genetic counseling for this family.MethodsA couple came to our hospital for pre-pregnancy genetic counseling. We collected the family history and detailed clinical information, then performed whole-exome sequencing, and analyzed the pathogenicity of the candidate mutations.ResultsWe found that the father of the proband had homocystinuria, the proband and his brother had low blood methionine levels at birth, and the brain MRI showed brain dysplasia. The third fetus was found to have a broadened triangle of the bilateral ventricle at 19 weeks of pregnancy. The compound heterozygous variants of c.602 A > C (p.His201Pro) and c.1316T > C (p.Leu439Pro) of the MTHFR gene in the first three fetuses were found by whole-exome sequencing. The heterozygous c.602 A > C variant of the MTHFR gene is a novel missense variant that has been submitted to the ClinVar with Variation ID 992,662.ConclusionIn consideration of the clinical phenotype, family history, and result of genetic testing, we speculated that both patients may have homocystinuria due to MTHFR deficiency. Homocystinuria due to MTHFR deficiency caused by compound heterozygous mutations composed of the MTHFR gene in this family may be associated with cerebral atrophy and cerebral dysplasia. The novel compound heterozygous mutations broaden the mutation spectrum of the MTHFR gene and enhance the application of genetic counseling and carrier screening in rare diseases.

Methionine regulates self-renewal, pluripotency, and cell death of GIC through cholesterol—rRNA axis

BackgroundGlioma-initiating cells (GICs) are the source of glioma cells that can self-renew, have pluripotency, and are treatment-resistant, so are the starting point for relapse and eventual death despite multimodality therapy. L-[methyl-11C] methionine PET has observed high accumulation at the time of recurrence, it is important to understand the mechanism of tumor cell activation caused by the reorganization of methionine metabolism. MethodsWe cultured cells in methionine-deprived culture medium for comprehensive analysis. Based on the obtained results, the possible target molecules were chemically inhibited and the respective markers were analyzed.ResultsMethionine depletion markedly decreased proliferation and increased cell death of GICs. Decreased S-adenosyl-methionine, which is synthesized intracellularly by catalyzed by methionine adenosyltransferase using methionine, triggered the following: (i) global DNA demethylation, (ii) hyper-methylation of signaling pathways regulating pluripotency of stem cells, (iii) decreased expression of the core-genes and pluripotent markers of stem cells including FOXM1, SOX2, SOX4, PROM1, and OLIG2, (iv) decreased cholesterol synthesis and increased excretion mainly through decreased SREBF2, and (v) down-regulation of the large subunit of ribosomal protein configured 28S and ACA43, small nucleolar RNA guiding the pseudouridylation of 28S rRNA, which is essential for translation. In addition, inhibition of cholesterol synthesis with statin resulted in a phenotype similar to that of methionine depletion and decreases in stem cell markers and small nucleolar RNA ACA43. Moreover, suppression of FOXM1 decreased stem cell markers such as SOX4 and PROM1. The gene expression profile for cholesterol production was obtained from the Ivy Glioblastoma Atlas Project database and compared between tumor cells with relatively low methionine levels in areas of pseudopalisading arrangement around necrosis and tumor cells in the infiltrating region, showing that cells in the infiltrating region have higher capacity to produce cholesterol.ConclusionsMethionine metabolism is closely related with self-renewal, pluripotency, and cell death in GICs through modification of cholesterol biosynthesis, especially in the SREBF2-FOXM1 and ACA43 axis with modification of rRNA.

Linkage of methionine addiction, histone lysine hypermethylation, and malignancy

SummaryMethionine addiction, found in all types of cancer investigated, is because of the overuse of methionine by cancer cells for excess transmethylation reactions. In the present study, we compared the histone H3 lysine-methylation status and degree of malignancy between methionine-addicted cancer cells and their isogenic methionine-independent revertants, selected by their growth in low concentration of methionine. The methionine-independent revertans can grow on low levels of methionine or independently of exogenous methionine using methionine precursors, as do normal cells. In the methionine-independent revertants, the excess levels of trimethylated histone H3 lysine marks found in the methionine-addicted parental cancer cells were reduced or lost, and their tumorigenicity and experimental metastatic potential in nude mice were also highly reduced. Methionine addiction of cancer is linked with malignancy and hypermethylation of histone H3 lysines. The results of the present study thus provide a unique framework to further understand a fundamental basis of malignancy.

CBMS-10 Methionine metabolism closely related with self-renew, pluripotency and cell death in GICs through modification of cholesterol biosynthesis and ribosomal RNA

Glioma initiating cells (GICs) are the source of glioma cells that have the ability to self-renew and pluripotency, which are treatment-resistant, starting point for relapse and eventual death despite multimodality therapy. Since high accumulation is observed in 11cMet-PET at the time of recurrence, it is important to understand the mechanism of tumor cell activation caused by the reorganization of methionine metabolism. We cultured cells in methionine-deprived culture medium and performed a comprehensive analysis, and found that methionine depletion markedly decreased proliferation and increasing cell death of GICs. Decreased SAM, which is synthesized intracellularly catalyzed by methionine adenosyltransferase (MAT) using methionine, triggered the following: (i) global DNA demethylation, (ii) hyper-methylation of signaling pathways regulating pluripotentcy of stem cells, (iii) decreased expression of the core-genes and pluripotent marker of stem cells including FOXM1, SOX2, SOX4, PROM1 and OLIG2, (iv) decreased cholesterol synthesis and increased excretion mainly through decreased SREBF2 (v) down-regulation of the large subunit of ribosomal protein configured 28S and ACA43, snoRNA guiding the pseudouridylation of 28S ribosomal RNA, which has crucial role for translation. In addition, inhibition of cholesterol synthesis with statin resulted in a phenotype similar to that of methionine removal and a decrease in stem cell markers and snoRNA ACA43. Moreover, suppression of FOXM1 decreased stem cell markers such as SOX4 and PROM1. The gene expression profile for cholesterol production was obtained from the Ivy Glioblastoma Atlas Project (IVYGAP) database and compared between tumour cells with relatively low methionine levels in area of pseudopalisading arrangement around necrosis and tumour cells in the infiltrating region, showing that cells cells in the infiltrating region have a higher capacity to produce cholesterol. Taken together, methionine metabolism closely related with self-renew, pluripotency and cell death in GICs through modification of cholesterol biosynthesis: especially SREBF2-FOXM1 and ACA43 axis with modification of ribosomal RNA.

Fish Protein and Its Derivatives: Functionality, Biotechnology and Health Effects

Animal derived proteins provide the essential amino acid requirements of a healthy diet. Among animal proteins, fish proteins have a well-balanced amino acid composition that are imperative for beneficial synthesizing and utilizing proteins in the body. Lack or low levels of any amino acid reduce the other amino acid utilization proportionately. This is why plant-derived proteins are potentially at a disadvantage for use in the body since they have relatively low levels of the essential amino acids methionine and lysine. Health studies have revealed that fish protein is suggested as a weight-loss diet to obese patients.

Fish Protein and Its Derivatives: Functionality, Biotechnology and Health Effects

Animal derived proteins provide the essential amino acid requirements of a healthy diet. Among animal proteins, fish proteins have a well-balanced amino acid composition that are imperative for beneficial synthesizing and utilizing proteins in the body. Lack or low levels of any amino acid reduce the other amino acid utilization proportionately. This is why plant-derived proteins are potentially at a disadvantage for use in the body since they have relatively low levels of the essential amino acids methionine and lysine. Health studies have revealed that fish protein is suggested as a weight-loss diet to obese patients.

The impact of general anesthesia on methionine metabolism during cardiopulmonary bypass

It has been found out that methylation of nucleic acids, proteins and low-molecular substrates is necessary to renew cellular structures, their restoration and cytoprotection. Methionine plays the most important role in this process but whether its metabolism changes during anesthesia and how different anesthetics affect it, has not yet been studied. The objective : to study the metabolism of methionine during cardiopulmonary bypass when the direct myocardial revascularization is performed and the impact of the anesthetics used (propofol, desflurane, and sevoflurane) on methionine metabolism. Subjects and methods : 74 patients who underwent surgery due to coronary heart disease with cardiopulmonary bypass were enrolled in the study. The patients were divided into three groups by the anesthetic used (desflurane, sevoflurane, propofol). Levels of methionine, homocysteine, cysteine, and taurine were tested in the blood collected from veins and jugular vein before the aorta clamping and after the release of clamps. Results . In all three groups, lower levels of methionine and a higher level of homocysteine were observed after the release of clamps from the aorta, especially in the jugular vein. The most significant consumption of methionine was noted when propofol was used. In the same group, the exocytic release of homocysteine into the blood and the formation of cysteine were significantly lower. No significant difference was observed in the effect of desflurane and sevoflurane on methylation. Conclusion . During the anoxia, the consumption of methionine increases significantly but the intensity of demethylation/remethylation depends on the anesthetics used during anesthesia. The most significant decrease in the level of methionine as well as the remethylation of homocysteine into methionine occurs with the use of propofol, rather than inhalation anesthetics which may be a consequence of desflurane and sevoflurane cytoprotective properties.

The Level of Methionine Residues in Storage Proteins Is the Main Limiting Factor of Protein-Bound-Methionine Accumulation in Arabidopsis Seeds.

The low level of methionine, an essential sulfur-containing amino acid, limits the nutritional quality of seeds. Two main factors can control the level of protein-bound methionine: the level of free methionine that limits protein accumulation and the methionine residues inside the storage proteins. To reveal the main limiting factor, we generated transgenic Arabidopsis thaliana seed-specific plants expressing the methionine-rich sunflower seed storage (SSA) protein (A1/A2). The contents of protein-bound methionine in the water-soluble protein fraction that includes the SSA in A1/A2 were 5.3- and 10.5-fold, respectively, compared to control, an empty vector (EV). This suggests that free methionine can support this accumulation. To elucidate if the level of free methionine could be increased further in the protein-bound methionine, these lines were crossed with previously characterized plants having higher levels of free methionine in seeds (called SSE). The progenies of the crosses (A1S, A2S) exhibited the highest level of protein-bound methionine, but this level did not differ significantly from A2, suggesting that all the methionine residues of A2 were filled with methionine. It also suggests that the content of methionine residues in the storage proteins is the main limiting factor. The results also proposed that the storage proteins can change their content in response to high levels of free methionine or SSA. This was assumed since the water-soluble protein fraction was highest in A1S/A2S as well as in SSE compared to EV and A1/A2. By using these seeds, we also aimed at gaining more knowledge about the link between high free methionine and the levels of metabolites that usually accumulate during abiotic stresses. This putative connection was derived from a previous analysis of SSE. The results of metabolic profiling showed that the levels of 29 and 20 out of the 56 metabolites were significantly higher in SSE and A1, respectively, that had higher level of free methionine, compared A1S/A2S, which had lower free methionine levels. This suggests a strong link between high free methionine and the accumulation of stress-associated metabolites.

Bioconversion of chitin and concomitant production of chitinase and N-acetylglucosamine by novel Achromobacter xylosoxidans isolated from shrimp waste disposal area

Marine pollution is a significant issue in recent decades, with the increase in industries and their waste harming the environment and ecosystems. Notably, the rise in shellfish industries contributes to tons of shellfish waste composed of up to 58% chitin. Chitin, the second most ample polymer next to cellulose, is insoluble and resistant to degradation. It requires chemical-based treatment or enzymatic hydrolysis to cleave the chitin polymers. The chemical-based treatment can lead to environmental pollution, so to solve this problem, enzymatic hydrolysis is the best option. Moreover, the resulting biopolymer by-products can be used to boost the fish immune system and also as drug delivery agents. Many marine microbial strains have chitinase producing ability. Nevertheless, we still lack an economical and highly stable chitinase enzyme for use in the industrial sector. So we isolate a novel marine bacterial strain Achromobacter xylosoxidans from the shrimp waste disposal site using chitin minimal medium. Placket–Burman and central composite design statistical models for culture condition optimisation predicted a 464.2 U/ml of chitinase production. The culture conditions were optimised for maximum chitinase production recording up to 467 U/ml. This chitinase from the A. xylosoxidans was 100% active at an optimum temperature of 45 °C (withstand up to 55 °C) and pH 8 with 80% stability. The HPLC analysis of chitinase degraded shellfish waste reveals a major amino acid profile composition—arginine, lysine, aspartic acid, alanine, threonine and low levels of isoleucine and methionine. These chitinase degraded products and by-products can be used as supplements in the aquaculture industry.

4006 Methionine Dependence in Cancer: From Metabolic Phenotype to Therapy

OBJECTIVES/GOALS: Methionine dependence was described 45 years ago as an increased reliance on an exogenous supply of the essential amino acid methionine in most cancer cells compared to normal cells. Methionine depletion, using either synthetic diets or the enzyme methioninase, potentiates the effects of chemotherapy and radiotherapy in tumor-bearing animal models. Two main obstacles prevent methionine dependence from integrating the clinical treatment of cancer. The first is the weight loss associated with methionine depletion therapy, increasing the risk of cachexia in patients. The second is the stubborn absence of a mechanism to explain the inability of cancer cells to adapt to low methionine levels. METHODS/STUDY POPULATION: To address these two obstacles, we are using an immunocompetent murine model of metastatic melanoma to compare the effects of complete methionine deprivation with a moderate, 75-80% methionine restriction similar to the one used to increase lifespan in animal models. In an effort to identify a mechanism of action, we also performed a proteomic screen of two melanoma cell lines divergent for methionine dependence under methionine stress. RESULTS/ANTICIPATED RESULTS: We recently showed that methionine restriction is sufficient to provide gains in treating local and metastatic lesions in vivo, without weight loss. We observed few differences in pathway activation between the two cell lines in response to methionine stress, despite proliferation being cut by half in the methionine dependent cell line. We expect that subcellular translocation events may provide further information on the molecular bases of methionine dependence. DISCUSSION/SIGNIFICANCE OF IMPACT: A moderate restriction in methionine is sufficient to recapitulate the benefits of methionine depletion in cancer, without weight loss. The mechanism behind this effect remains unknown. This work contributes towards the integration of methionine dependence into clinical practice and the discovery of novel drug targets.

Methylene Tetrahydrofolate Reductase Deficiency.

5,10-Methylene-tetrahydrofolate reductase (MTHFR) deficiency is a rare, autosomal recessive, metabolic disorder of folate metabolism, which affects homocysteine remethylation. Elevated homocysteine with normal or low methionine level is the key to diagnosis. Early recognition and treatment with betaine, has been shown to improve the survival and neurological outcomes. The authors report five Indian patients from three unrelated families, with MTHFR deficiency to emphasize the importance of early recognition and initiation of specific treatment.

Association of Homocysteine, Methionine, and MTHFR 677C>T Polymorphism With Rate of Cardiovascular Multimorbidity Development in Older Adults in Sweden

Strong evidence links high total serum homocysteine (tHcy) and low methionine (Met) levels with higher risk of ischemic disease, but other cardiovascular (CV) diseases may also be associated with their pleiotropic effects. To investigate the association of serum concentrations of tHcy and Met with the rate of CV multimorbidity development in older adults and to explore the role of methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism in this association. The Swedish National Study on Aging and Care in Kungsholmen is a cohort study of randomly selected individuals aged 60 years or older. The present study included data on 1969 individuals with complete information and without CV diseases at baseline, collected from the baseline examination (2001-2004) to the fourth follow-up (2013-2016). Data analysis was conducted from January to May 2019. Concentrations of tHcy and Met were measured from nonfasting venous blood samples. The Met:tHcy ratio was considered a possible indicator of methylation activity. MTHFR status was dichotomized as any T carriers vs noncarriers. The number of CV diseases at each wave was ascertained based on medical interviews and records, laboratory test results, and drug data. Linear mixed models were used to study the association of baseline tHcy and Met levels and the rate of CV multimorbidity development, adjusting for sociodemographic characteristics, CV risk factors, chronic disease burden, and drug use. Of 1969 participants, most were women (1261 [64.0%]), with a mean (SD) age of 70.9 (9.8) years; 1703 participants (86.6%) had at least a high school level of education. Baseline measurements of serum tHcy, Met, and the Met:tHcy ratio were associated with the rate of CV disease accumulation (tHcy: β = 0.023 per year; 95% CI, 0.015 to 0.030; P < .001; Met: β = -0.007 per year; 95% CI, -0.013 to -0.001; P = .02; Met:tHcy ratio: β = -0.017 per year; 95% CI, -0.023 to -0.011; P < .001). The association between low Met concentrations and the rate of CV multimorbidity development was restricted to the group with CT/TT alleles of MTHFR (β = 0.023 per year; 95% CI, 0.006 to 0.041; P = .009). Results remained largely significant when individual CV diseases were removed from the total count 1 at a time (eg, ischemic heart disease, tHcy: β = 0.023 per year; 95% CI, 0.013 to 0.027; P < .001; Met: β = -0.006 per year; 95% CI, -0.011 to -0.0003; P = .04; Met:tHcy ratio: β = -0.015 per year; 95% CI, -0.020 to -0.009; P < .001). In this study, high tHcy and low Met levels were associated with faster CV multimorbidity development in older age. The interactive association of Met concentrations and MTHFR polymorphism, together with the association found for the Met:tHcy ratio, point toward the relevance of impaired methylation in the pathogenesis of CV aging.

Effects of lysine and methionine in a low crude protein diet on the growth performance and gene expression of immunity genes in broilers

Globally, the poultry industry is 1 of the most advanced livestock industries. Feed contributes to the biggest proportion (65–70%) of the production cost. Most feed ingredients in Malaysia are imported, which contributes to the high food bill annually, and alternative feed formulation may help decrease the cost of poultry feed. Feed formulation are improved to efficiently meet the dietary requirements of the broilers and 1 of the ways is by reducing the level of crude protein in the diet while supplementing essential amino acids. In this study, the effects of methionine and lysine, which are the 2 most limiting amino acids in the chicken diet, were supplemented in a low crude protein diet, and its effects on the growth and expression of immunity genes such as MUC2, SLC, GAL6, and LEAP-2 were studied. A total of 300 Cobb500 broilers were tested with 10 different dietary treatments. Experimental treatment diets consist of high, standard, and low levels of methionine and lysine in the diet with reduced crude protein. The control group consists of diet with standard levels of lysine, methionine, and crude protein as recommended for Cobb500 broilers. Ribonucleic acid was extracted from the jejunum, spleen, and liver for gene expression analysis which was performed with real-time polymerase chain reaction using SYBR Green chemistry. Results of the growth performance at 6 wk showed improved feed conversion ratio when lysine was increased by 0.2% in a low crude protein diet at 1.96 ± 0.11. Gene expression of MUC2 gene in the jejunum showed a significant increase across all experimental diets with the treatment with higher lysine in low crude protein diet with the highest increase of 3.8 times as compared with the control diet. The other genes expressed in the spleen and liver were mostly downregulated. It was concluded that supplementation of high lysine with standard methionine in a low crude protein diet performed better in terms of lowest feed conversion ratio and high upregulation of MUC2 gene.

The effect of different dietary ratios of lysine and arginine in diets with high or low methionine levels on oxidative and epigenetic DNA damage, the gene expression of tight junction proteins and selected metabolic parameters in Clostridium perfringens-challenged turkeys

Two experiments were performed to investigate the effect of different ratios of arginine (Arg) to lysine (Lys) in diets with low (30% Lys; Experiment 1) and high (45% Lys; Experiment 2) methionine (Met) levels on selected metabolic parameters, oxidative and epigenetic DNA damage, and the mechanisms underlying intestinal barrier integrity in turkeys challenged with Clostridium perfringens. In each experiment, 108 one-day-old Hybrid Converter female turkeys were placed in 6 pens (18 birds per pen) and reared for 42 days. At 34, 36 and 37 days of age, half of the birds were subjected to C. perfringens challenge. A 3 × 2 factorial design with three levels of Arg relative to Lys (90, 100 and 110%; Arg90, Arg100 and Arg110, respectively) and C. perfringens infection (−, +) was employed. Challenging birds with C. perfringens increased lipid oxidation and the oxidation and methylation of DNA of intestinal mucosa, and down-regulated the activities of DNA-repairing enzymes. Neither the dietary treatment nor the challenge affected the markers of liver function or metabolism. Arg110 diets with the high Met level induced DNA oxidation and methylation whereas these processes were downregulated in birds fed Arg90 diets. The results indicate that Arg90 diets with high Met levels have a beneficial influence on the indicators of intestinal barrier integrity in turkeys with necrotic enteritis (NE). Despite the analyzed amino acid ratios interacted with the systems responsible for the maintenance of gut integrity in the host organism, this dietary intervention probably enabled birds to cope with NE.

HP1s modulate the S-Adenosyl Methionine synthesis pathway in liver cancer cells.

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer in adults. Among the altered pathways leading to HCC, an increasing role is attributed to abnormal epigenetic regulation. Members of the Heterochromatin Protein (HP1) 1 family are key players in chromatin organisation, acting as docking sites for chromatin modifiers. Here, we inactivated HP1α in HepG2 human liver carcinoma cells and showed that HP1α participated in cell proliferation. HP1α-depleted cells have a global decrease in DNA methylation and consequently a perturbed chromatin organisation, as exemplified by the reactivation of transcription at centromeric and pericentromeric regions, eventhough the protein levels of chromatin writers depositing methylation marks, such as EZH2, SETDB1, SUV39H1, G9A and DNMT3A remained unaltered. This decrease was attributed mainly to a low S-Adenosyl Methionine (SAM) level, a cofactor involved in methylation processes. Furthermore, we showed that this decrease was due to a modification in the Methionine adenosyl transferase 2A RNA (MAT2A) level, which modifies the ratio of MAT1A/MAT2A, two enzymes that generate SAM. Importantly, HP1α reintroduction into HP1α-depleted cells restored the MAT2A protein to its initial level. Finally, we demonstrated that this transcriptional deregulation of MAT2A in HP1α-depleted cells relied on a lack of recruitment of HP1β and HP1γ to MAT2A promoter where an improper non-CpG methylation site was promoted in the vicinity of the transcription start site where HP1β and HP1γ bound. Altogether, these results highlight an unanticipated link between HP1 and the SAM synthesis pathway, and emphasise emerging functions of HP1s as sensors of some aspects of liver cell metabolism.

Supplementation of diets with Brazil nut powder can meet dietary methionine requirement of organic broiler chickens

Synthetic amino acids are not permitted in organic feeds by the National Organic Standard Board (NOSB) in the USA. However, low levels of methionine (Met) are permitted, and the NOSB recommends 0.1% synthetic Met for broilers. Inadequate level of dietary methionine poses concerns pertaining to health and welfare of broilers, as these limitations lead to possible Met deficiency. This research examined the effects of complete replacement of synthetic DL-methionine (DLM) by Brazil nut powder in a 100% organic diet. Eight hundred Ross 308 chicks were hatched and randomly divided into 4 treatments with 4 replicates of 50 chicks and raised for 56 days. Treatments included birds fed a conventional diet and raised organically (Conv_Org), NOSB diet raised organically (NOSB_Org), 100% organic diet and raised organically (Org_Org), and a conventional diet raised conventionally (Conv_Conv). Body weight at 56 days were 3960, 3995, 3981, and 3676 g for Conv_Org, NOSB_Org, Org_Org, and Conv_Conv, respectively. Body weights of the Conv_Conv group were lower (P < 0.05) than the other treatments. The FCR (0–8 weeks) of Org_Org treatment was lower (P < 0.05) than the NOSB diet. The birds on the NOSB diet had increased feed intake perhaps to compensate for the deficiency in Met. The NOSB diet may not sufficiently meet the requirement of broiler chickens even when raised with access to pasture. There were no differences in carcass yield and composition in any treatment. We conclude that Brazil nut powder is a viable substitute for DLM in organically raised broilers, as there were no differences in growth and carcass yield and improved FCR when compared to current NOSB recommended diet.