[Intervention effect of Erchen Decoction on methionine and choline deficient diet-induced non-alcoholic steatohepatitis in mice].

This study investigated the effect of Erchen Decoction(ECD) on the prevention of non-alcoholic steatohepatitis(NASH) in mice and explored its possible mechanism, so as to provide scientific data for the clinical application of ECD in the prevention of NASH. C57BL/6 male mice were randomly divided into normal group(methionine and choline supplement, MCS), model group(methionine and choline deficient, MCD), low-dose ECD group(ECD＿L, 6 g·kg~(-1)), medium-dose ECD group(ECD＿M, 12 g·kg~(-1)), and high-dose ECD group(ECD＿H, 24 g·kg~(-1)), with eight mice in each group. The MCS group was fed with an MCS diet, and the other groups were fed with an MCD diet. The mice in each group were given corresponding diets, but the drug intervention group was given low-, medium-, and high-dose ECD(10 mL·kg~(-1)·d~(-1)) by intragastric administration for six weeks on the basis of MCD diet feeding, and the mice could eat and drink freely during the whole experiment. At the end of the experiment, mice were fasted overnight(12 h) and were anesthetized with 20% urethane. Thereafter, the blood and liver tissue were collected. The serum was used to detect the levels of alanine aminotransferase(ALT), aspartate aminotransaminase(AST), interleukin-1ß(IL-1ß), interleukin-6(IL-6), interleukin-10(IL-10), and tumor necrosis factor-α(TNF-α). Liver tissue was processed by hematoxylin-eosin(HE) staining and used for hepatic histological analysis and detection of the expression levels of genes and proteins related to nuclear factor erythroid 2-related factor 2/glutathione peroxidase 4(Nrf2/GPX4) pathway by real-time quantitative reverse transcriptase-polymerase chain reaction(RT-qPCR) and Western blot analysis, respectively. The results showed that compared with the MCS group, the MCD group showed higher serum ALT and AST levels; the HE staining exhibited fat vacuoles and obvious inflammatory cell infiltration in liver tissue; serum IL-1ß, IL-6, and TNF-α levels were significantly increased, and the serum IL-10 level was significantly decreased. The mRNA expressions of fatty acid synthase(FASN), monocyte chemoattractant protein-1(MCP-1), and IL-1ß in liver tissue were significantly up-regulated, while those of GPX4, Nrf2, and NAD(P)H:quinine oxidoreductase(NQO1) were significantly down-regulated. Compared with the MCD group, the serum ALT and AST levels of ECD＿M and ECD＿H groups were significantly decreased, and the AST level in the ECD＿L group was significantly decreased. The number of fat vacuoles and the degree of inflammatory cell infiltration in liver tissue were improved; serum IL-1ß, IL-6, and TNF-α levels were significantly decreased, but the serum IL-10 level was significantly increased only in the ECD＿H group. The mRNA expressions of FASN, MCP-1, and IL-1ß in liver tissue were significantly down-regulated, and those of GPX4 and NQO1 were significantly up-regulated. The mRNA expressions of Nrf2 in ECD＿M and ECD＿H groups were significantly up-regulated. Western blot results showed that compared with the MCD group, the protein expression levels of Nrf2 and GPX4 in each group were significantly increased after ECD administration, and the protein expression level of FASN was significantly decreased; the protein expression of NQO1 was increased in ECD＿M and ECD＿H groups. In summary, ECD can reduce hepatic lipid accumulation, oxidative stress, liver inflammation, and liver injury in NASH mice, which may be related to the activation of the Nrf2/GPX4 pathway.

Measuring bioavailability, utilization, and excretion of rumen-protected lysine in lactating cows using an isotope technique.

Supplementing a diet with rumen-protected amino acids (AAs) is a common feeding strategy for efficient production. For a cost-effective use of rumen-protected AA, the accurate bioavailability of rumen-protected amino acids should be known and their metabolism after absorption needs to be well understood. The current study determined the bioavailability, absorption, utilization, and excretion of rumen-protected Lys (RP-Lys). Four ruminally cannulated cows in a 4 × 4 Latin square design (12 d for diet adaptation; 5 or 6 d for total collections) received the following treatments: L0, a basal diet; L25, the basal diet and L-Lys infused into the abomasum to provide 25.9 g/d L-Lys; L50, the basal diet and L-Lys infused into the abomasum to provide 51.8 g/d L-Lys; and RPL, the basal diet supplemented with 105 g/d (as-is) of RP-Lys to provide 26.7 g of digestible Lys. During the last 5 or 6 d in each period, 15N-Lys (0.38 g/d) was infused into the abomasum for all cows to label the pool of AA, and the total collection of milk, urine, and feces were conducted. 15N enrichment of samples on d 4 and 5 were used to calculate the bioavailability and Lys metabolism. We used a model containing a fast AA turnover (≤ 5 d) and slow AA turnover pool (> 5 d) to calculate fluxes of Lys. The Lys flux to the fast AA turnover pool (absorbed Lys + Lys from the slow AA turnover pool to fast AA turnover pool) was calculated using 15N enrichment of milk Lys. The flux of Lys from the fast AA turnover pool to milk and urine was calculated using 15N transfer into milk and urine. Then, absorbed Lys was estimated by the sum of Lys flux to milk and urine assuming no net utilization of Lys by body tissues. Duodenal Lys flow was estimated by 15N enrichment of fecal Lys. The bioavailability of RP-Lys was calculated from duodenal Lys flows and Lys absorption for RPL. Increasing Lys supply from L25 to L50 increased Lys utilization for milk by 9 g/d but also increased urinary excretion by 10 g/d. For RPL, absorbed Lys was estimated to be 136 g/d where 28 g of absorbed Lys originated from RP-Lys. In conclusion, 68% of bioavailability was obtained for RP-Lys. The Lys provided from RP-Lys was not only utilized for milk protein (48%) but also excreted in urine (20%) after oxidation.

Relative biological efficacy of methionine hydroxy analogue-free acid compared to dl-methionine in the broiler chickens.

BACKGROUND: In the broiler's diets based on corn-soya bean meal, methionine (Met) and cystine (Cys), known as sulphur amino acids (SAAs), are the first limiting indispensable amino acids because of their limited presence, which are supplemented with different synthetic sources. Evaluation of the biological effectiveness of these sources can be important in their correct replacement, especially in the starter and growth diets. OBJECTIVES: The current study was done to assess the relative biological efficacy (RBE) of liquid Met hydroxy analogue-free acid (MHA-FA) in comparison with dl-Met (dl-Met) based on broiler performance traits at different levels of digestible SAA in the 1-11 (starter) and 11-25 (grower) days of age periods. METHODS: Two experiments were developed with treatments consisting of a basal diet without Met addition that met the nutrient and energy requirements of broilers with the exception of SAAs (Met + Cys) and five increasing Met doses for both sources (dl-Met and/or MHA-FA), resulting in digestible SAA concentrations from 0.62% to 1.02% of diet in the starter period (Trial 1) and 0.59% to 0.94% of diet in the grower period (Trial 2). The multi-linear regression model and slope ratio method were employed to calculate the RBE of MHA-FA compared with dl-Met for measured variables. RESULTS: In both experiments, the results obtained during the starter and grower periods with the different Met supplementations show significant growth responses to digestible SAAs levels. By increasing dietary dl-Met and/or MHA-FA levels, the growth performance traits and immune responses were improved (quadratic; p < 0.05). The RBE of MHA-FA compared to dl-Met on an equimolar basis was estimated 66%-89% (59%-79% on a weight-to-weight basis). CONCLUSIONS: It is concluded that the RBE of MHA-FA in comparison with dl-Met depends on broiler chicken age and what attribute is being evaluated.

A novel methionine nanoparticle in broiler chickens: Bioavailability and requirements.

This bioassay evaluated the bioavailability (RBV) of a novel nanoparticle of methionine (nano-Met) relative to DL-methionine (DL-Met), and estimated methionine requirements for both sources in starting broilers. Five supplemental levels (0.05, 0.10, 0.15, 0.20, and 0.25% of diet) of DL-Met or nano-Met were added to a basal diet containing 0.35% standardized ileal digestible (SID) methionine to create 11 experimental diets, including a basal diet and 10 experimental diets containing 0.40, 0.45, 0.50, 0.55, and 0.60% SID-Met, respectively. A total of 825 one-day-old male Ross 308 birds were randomly assigned to 11 treatments with 5 pen replicates and 15 birds each. Body weight gain (BWG), breast meat yield (BMY), and thigh meat yield (TMY) increased (P < 0.001) while feed conversion ratio (FCR) and malondialdehyde (MDA) concentration in meat samples decreased (P < 0.001) with increasing dietary methionine. Based on the slope-ratio method, the RBV of nano-Met relative to DL-Met for BWG, FCR, and TMY were 102 (48-155%; R2 = 0.71), 134 (68-201%; R2 = 0.77), and 110% (27-193%; R2 = 0.55), respectively. Considering the statistical accuracy of the spline models, the estimated values of DL-Met for maximum BWG and nano-Met for maximum TMY were 0.578% and 0.561%, respectively, which were statistically higher than those recommended for commercial settings. The highest effect size of supplemental methionine was on MDA (ƞ2p = 0.924), followed by FCR (ƞ2p = 0.578), BMY (ƞ2p = 0.575), BWG (ƞ2p = 0.430), and TMY (ƞ2p = 0.332), suggesting the potent antioxidant properties of methionine. Our findings suggest that reducing the particle size of DL-Met to nanoparticles could be a promising strategy to enhance the efficiency of methionine supplementation in broilers, an idea that requires further investigation in future research.

Methionyl-Methionine Dipeptide Enhances Mammogenesis and Lactogenesis by Suppressing the Expression of a Novel Long Noncoding RNA MGPNCR to Inhibit eIF4B Dephosphorylation.

Previous research has demonstrated that in pregnant mice deficient in l-methionine (Met), the mixture of the dipeptide l-methionyl-l-methionine (Met-Met) with Met was more effective than Met alone in promoting mammogenesis and lactogenesis. This study aimed to investigate the role of a novel long noncoding RNA (lncRNA), named mammary gland proliferation-associated lncRNA (MGPNCR), in these processes. Transcriptomic analysis of mammary tissues from Met-deficient mice, supplemented either with a Met-Met/Met mixture or with Met alone, revealed significantly higher MGPNCR expression in the Met group compared to the mixture group, a finding recapitulated in a mammary epithelial cell model. Our findings suggested that MGPNCR hindered mammogenesis and milk protein synthesis by binding to eukaryotic initiation factor 4B (eIF4B). This interaction promoted the dephosphorylation of eIF4B at serine-422 by enhancing its association with protein phosphatase 2A (PP2A). Our study sheds light on the regulatory mechanisms of lncRNA-mediated dipeptide effects on mammary cell proliferation and milk protein synthesis. These insights underscore the potential benefits of utilizing dipeptides to improve milk protein in animals and potentially in humans.

Systemic intracellular analysis for balancing complex biosynthesis in a transcriptionally deregulated Escherichia coli l-Methionine producer.

l-Methionine (l-Met) has gained remarkable interest due to its multifaceted and versatile applications in the fields of nutrition, pharmaceuticals and clinical practice. In this study, the fluxes of the challenging l-Met biosynthesis in the producer strain Escherichia coli (E. coli) DM2853 were fine-tuned to enable improved l-Met production. The potential bottlenecks identified in sulfur assimilation and l-Met synthesis downstream of O-succinyl-l-homoserine (OSHS) were addressed by overexpressing glutaredoxin 1 (grxA), thiosulfate sulfurtransferase (pspE) and O-succinylhomoserine lyase (metB). Although deemed as a straightforward target for improving glucose-to-Met conversion, the yields remained at approximately 12%-13% (g/g). Instead, intracellular l-Met pools increased by up to four-fold with accelerated kinetics. Overexpression of the Met exporter ygaZH may serve as a proper valve for releasing the rising internal Met pressure. Interestingly, the export kinetics revealed maximum saturated export rates already at low growth rates. This scenario is particularly advantageous for large-scale fermentation when product formation is ideally uncoupled from biomass formation to achieve maximum performance within the technical limits of large-scale bioreactors.

Methionine Supplementation Alleviates the Germ Cell Apoptosis Increased by Maternal Caffeine Intake in a C. elegans Model.

Caffeine (1,3,7-trimethylxanthine) is a widely consumed bioactive substance worldwide. Our recent study showed that a reduction in both reproduction and yolk protein production (vitellogenesis) caused by caffeine intake were improved by vitamin B12 supplementation, which is an essential co-factor in methionine metabolism. In the current study, we investigated the role of methionine in the reproduction of caffeine-ingested animals (CIAs). We assessed the effect of methionine metabolism on CIAs and found that caffeine intake decreased both methionine levels and essential enzymes related to the methionine cycle. Furthermore, we found that the caffeine-induced impairment of methionine metabolism decreased vitellogenesis and increased germ cell apoptosis in an LIN-35/RB-dependent manner. Interestingly, the increased germ cell apoptosis was restored to normal levels by methionine supplementation in CIAs. These results indicate that methionine supplementation plays a beneficial role in germ cell health and offspring development by regulating vitellogenesis.

The Development of LAT1 Efflux Agonists as Mechanistic Probes of Cellular Amino Acid Stress.

Amino acid restriction induces cellular stress and cells often respond via the induction of autophagy. Autophagy or 'self-eating' enables the recycling of proteins and provides the essential amino acids needed for cell survival. Of the naturally occurring amino acids, methionine restriction has pleiotropic effects on cells because methionine also contributes to the intracellular methyl pools required for epigenetic controls as well as polyamine biosynthesis. In this report, we describe the chemical synthesis of four diastereomers of a methionine depletion agent and demonstrate how controlled methionine efflux from cells significantly reduces intracellular methionine, S-adenosylmethionine (SAM), S-adenosyl homocysteine (SAH), and polyamine levels. We also demonstrate that human pancreatic cancer cells respond via a lipid signaling pathway to induce autophagy. The methionine depletion agent causes the large amino acid transporter 1 (LAT1) to preferentially work in reverse and export the cell's methionine (and leucine) stores. The four diastereomers of the lead methionine/leucine depletion agent were synthesized and evaluated for their ability to (a) efflux 3H-leucine from cells, (b) dock to LAT1 in silico, (c) modulate intracellular SAM, SAH, and phosphatidylethanolamine (PE) pools, and (d) induce the formation of the autophagy-associated LC3-II marker. The ability to modulate the intracellular concentration of methionine regardless of exogenous methionine supply provides new molecular tools to better understand cancer response pathways. This information can then be used to design improved therapeutics that target downstream methionine-dependent processes like polyamines.

Piperine alleviates nonalcoholic steatohepatitis by inhibiting NF-κB-mediated hepatocyte pyroptosis.

PURPOSE: Nonalcoholic steatohepatitis (NASH) is the progressive form of nonalcoholic fatty liver disease (NAFLD), which has a high risk of cirrhosis, liver failure, and hepatocellular carcinoma. Piperine (Pip) is an extract of plants with powerful anti-inflammatory effects, however, the function of Pip in NASH remains elusive. Here, we aim to explore the role of Pip in NASH and to find the possible mechanisms. METHODS: Methionine and choline-deficient (MCD) diets were used to induce steatohepatitis, methionine- and choline-sufficient (MCS) diets were used as the control. After Pip treatment, H&E staining, Oil Red O staining, hepatic triglyceride (TG) content and F4/80 expression were performed to analysis liver steatosis and inflammation; Masson's staining, COL1A1 and α-SMA were detected liver fibrosis. Lipopolysaccharide (LPS) -treated AML12 cells were used to as the cell model to induce pyroptosis. Then, pyroptosis-related proteins, IL-1ß and LDH release were detected in vivo and in vitro. Finally, NF-κB inhibitor, BAY11-7082, was used to further demonstrate the mechanism of Pip in NASH. RESULTS: The study found that Pip alleviated liver steatosis, inflammation, hepatocyte injury, and fibrosis in mice fed with MCD diets. Moreover, the pyroptosis markers (NLRP3, ASC, caspase-1 p20, and GSDMD), IL-1ß and LDH release were decreased by Pip treatment. NF-κB activation was suppressed by Pip treatment and pyroptosis-related proteins were down regulated by BAY11-7082. CONCLUSION: Pip ameliorates NASH progression, and the therapeutical effect was associated with inhibition of hepatocyte pyroptosis induced by NF-κB.

Si-Wu-Tang attenuates hepatocyte PANoptosis and M1 polarization of macrophages in non-alcoholic fatty liver disease by influencing the intercellular transfer of mtDNA.

ETHNOPHARMACOLOGICAL RELEVANCE: Non-alcoholic fatty liver disease (NAFLD) represents a burgeoning challenge for public health with potential progression to malignant liver diseases. PANoptosis, an avant-garde conceptualization of cell deaths, is closely associated with mitochondrial damage and linked to multiple liver disorders. Si-Wu-Tang (SWT), a traditional Chinese herbal prescription renowned for regulating blood-related disorders and ameliorating gynecological and hepatic diseases, has been demonstrated to alleviate liver fibrosis by regulating bile acid metabolism and immune responses. AIM OF THE STUDY: However, the mechanisms by which mtDNA is released from PANoptotic hepatocytes, triggering macrophage activation and hepatitis and whether this process can be reversed by SWT remain unclear. MATERIALS AND METHODS: Here, sophisticated RNA-sequencing complemented by molecular approaches were applied to explore the underlying mechanism of SWT against NAFLD in methionine/choline-deficient diet (MCD)-induced mice and relative in vitro models. RESULTS: We revealed that SWT profoundly repaired mitochondrial dysfunction, blocked mitochondrial permeability transition and mtDNA released to the cytoplasm, subsequently reversing hepatocyte PANoptosis and macrophage polarization both in MCD-stimulated mice and in vitro. Mechanically, loaded lipids dramatically promoted the opening of mPTP and oligomerization of VDAC2 to orchestrate mtDNA release, which was combined with ZBP1 to promote hepatocyte PANoptosis and also taken by macrophages to trigger M1 polarization via the FSTL1 and PKM2 combination. SWT effectively blocked NOXA signaling and reversed all these detrimental outcomes. CONCLUSION: Our findings show that SWT protects against hepatitis-mediated hepatocyte PANoptosis and macrophage M1 polarization by influencing intrahepatic synthesis, release and intercellular transfer of mtDNA, suggesting a potential therapeutic strategy for ameliorating NAFLD.

KLF10/CBS increases the sensitivity of gastric carcinoma cells to methionine restriction by promoting sulfur transfer pathway.

Gastric cancer metastasis is a major cause of poor prognosis. Our previous research showed that methionine restriction (MR) lowers the invasiveness and motility of gastric carcinoma. In this study, we investigated the particular mechanisms of MR on gastric carcinoma metastasis. In vitro, gastric carcinoma cells (AGS, SNU-5, MKN7, KATO III, SNU-1, and MKN45) were grown in an MR medium for 24 h. In vivo, BALB/c mice were given a methionine-free (Met-) diet. Transwell assays were used to investigate cell invasion and migration. The amounts of Krüppel like factor 10 (KLF10) and cystathionine ß-synthase (CBS) were determined using quantitative real-time PCR and Western blot. To determine the relationship between KLF10 and CBS, chromatin immunoprecipitation and a dual-luciferase reporter experiment were used. Hematoxylin-eosin staining was used to detect lung metastasis. Liquid chromatography-mass spectrometry was used to determine cystathionine content. MR therapy had varying effects on the invasion and migration of gastric carcinoma cells AGS, SNU-5, MKN7, KATO III, SNU-1, and MKN45. KLF10 was highly expressed in AGS cells but poorly expressed in KATO III cells. KLF10 improved MR's ability to prevent gastric carcinoma cell invasion and migration. In addition, KLF10 may interact with CBS, facilitating transcription. Further detection revealed that inhibiting the KLF10/CBS-mediated trans-sulfur pathway lowered Met-'s inhibitory effect on lung metastasis development. KLF10 transcription activated CBS, accelerated the trans-sulfur pathway, and increased gastric carcinoma cells' susceptibility to MR.

Escherichia coli possessing the dihydroxyacetone phosphate shunt utilize 5'-deoxynucleosides for growth.

All organisms utilize S-adenosyl-l-methionine (SAM) as a key co-substrate for the methylation of biological molecules, the synthesis of polyamines, and radical SAM reactions. When these processes occur, 5'-deoxy-nucleosides are formed as byproducts such as S-adenosyl-l-homocysteine, 5'-methylthioadenosine (MTA), and 5'-deoxyadenosine (5dAdo). A prevalent pathway found in bacteria for the metabolism of MTA and 5dAdo is the dihydroxyacetone phosphate (DHAP) shunt, which converts these compounds into dihydroxyacetone phosphate and 2-methylthioacetaldehyde or acetaldehyde, respectively. Previous work in other organisms has shown that the DHAP shunt can enable methionine synthesis from MTA or serve as an MTA and 5dAdo detoxification pathway. Rather, the DHAP shunt in Escherichia coli ATCC 25922, when introduced into E. coli K-12, enables the use of 5dAdo and MTA as a carbon source for growth. When MTA is the substrate, the sulfur component is not significantly recycled back to methionine but rather accumulates as 2-methylthioethanol, which is slowly oxidized non-enzymatically under aerobic conditions. The DHAP shunt in ATCC 25922 is active under oxic and anoxic conditions. Growth using 5-deoxy-d-ribose was observed during aerobic respiration and anaerobic respiration with Trimethylamine N-oxide (TMAO), but not during fermentation or respiration with nitrate. This suggests the DHAP shunt may only be relevant for extraintestinal pathogenic E. coli lineages with the DHAP shunt that inhabit oxic or TMAO-rich extraintestinal environments. This reveals a heretofore overlooked role of the DHAP shunt in carbon and energy metabolism from ubiquitous SAM utilization byproducts and suggests a similar role may occur in other pathogenic and non-pathogenic bacteria with the DHAP shunt. IMPORTANCE: The acquisition and utilization of organic compounds that serve as growth substrates are essential for Escherichia coli to grow and multiply. Ubiquitous enzymatic reactions involving S-adenosyl-l-methionine as a co-substrate by all organisms result in the formation of the 5'-deoxy-nucleoside byproducts, 5'-methylthioadenosine and 5'-deoxyadenosine. All E. coli possess a conserved nucleosidase that cleaves these 5'-deoxy-nucleosides into 5-deoxy-pentose sugars for adenine salvage. The DHAP shunt pathway is found in some extraintestinal pathogenic E. coli, but its function in E. coli possessing it has remained unknown. This study reveals that the DHAP shunt enables the utilization of 5'-deoxy-nucleosides and 5-deoxy-pentose sugars as growth substrates in E. coli strains with the pathway during aerobic respiration and anaerobic respiration with TMAO, but not fermentative growth. This provides an insight into the diversity of sugar compounds accessible by E. coli with the DHAP shunt and suggests that the DHAP shunt is primarily relevant in oxic or TMAO-rich extraintestinal environments.

Highly chromophoric fluorescent-labeled methionyl-initiator tRNAs applicable in living cells.

Fluorescent initiator tRNAs (tRNAi) play a crucial role in studying protein synthesis, yet generating highly fluorescent tRNAi complexes remains challenging. We present an optimized strategy to effectively generate highly fluorescent initiator-tRNA complexes in living cells. Our strategy allows the generation of Fluo-Met-tRNAiMet complexes. These complexes can have highly chromogenic N-terminal labeling. For generating such complexes, we use either purified fluorescent methionine (PFM) or non-purified fluorescently labeled methionine (NPFM). Furthermore, PFM promotes the active generation of endogenous tRNAi in cells, leading to highly efficient Fluo-Met-tRNAiMet complexes. Finally, PFM-tRNAiMet complexes also facilitate the visualization of native fluorescently labeled Tat binding to beads. This demonstrates the potential of our approach to advance precision protein engineering and biotechnology applications.

[Optimization of the fermentative production of L-methionine by engineered Escherichia coli].

As the only essential amino acid containing elemental sulphur, L-methionine has important physiological and biochemical functions in living organisms. However, the fermentative production of L-methionine has not met the requirements of industrial production because of its low production level. In this paper, the fermentation process of an efficient L-methionine producing strain E. coli W3110ΔIJAHFEBC trc-fliY trc-malY/PAM glyA-22 metF constructed previously was systematically optimized. Based on the optimal initial glucose concentration, the effects of different fed-batch fermentation processes, including DO-Stat, pH-Stat, controlling residual sugar control at different level and feeding glucose with constant rate, on L-methionine fermentation were studied. It was found that the control of glucose concentration greatly affected the fermentation process. Subsequently, an optimal fed-batch fermentation process was developed, where the L-methionine titer was increased to 31.71 g/L, the highest yield reported to date, while the fermentation time was shortened to 68 h. Meanwhile, a fermentation kinetics model under the optimal fed-batch fermentation conditions was established, which fitted well with the biosynthesis process of L-methionine. This study may facilitate further development of the fermentative production of L-methionine.

A review on L-methioninase in cancer therapy: Precision targeting, advancements and diverse applications for a promising future.

Cancer remains a global health challenge, demanding novel therapeutic options due to the debilitating side effects of conventional treatments on healthy tissues. The review highlights the potential of L-methioninase, a pyridoxal-5-phosphate (PLP)-dependent enzyme, as a promising avenue in alternative cancer therapy. L-methioninase offers a unique advantage, its ability to selectively target and inhibit the growth of cancer cells without harming healthy cells. This selectivity arises because tumor cells lack an essential enzyme called methionine synthase, which healthy cells use to make the vital amino acid L-methionine. Several sources harbor L-methioninase, including bacteria, fungi, plants, and protozoa. Future research efforts can explore and exploit this diverse range of sources to improve the therapeutic potential of L-methioninase in the fight against cancer. Despite challenges, research actively explores microbial L-methioninase for its anticancer potential. This review examines the enzyme's side effects, advancements in combination therapies, recombinant technologies, polymer conjugation and novel delivery methods like nanoparticles, while highlighting the success of oral administration in preclinical trials. Beyond its promising role in cancer therapy, L-methioninase holds potential applications in food science, antioxidants, and various health concerns like diabetes, cardiovascular issues, and neurodegenerative diseases. This review provides a piece of current knowledge and future prospects of L-methioninase, exploring its diverse therapeutic potential.

The luxS deletion reduces the spoilage ability of Shewanella putrefaciens: An analysis focusing on quorum sensing and activated methyl cycle.

The luxS mutant strains of Shewanella putrefaciens (SHP) were constructed to investigate the regulations of gene luxS in spoilage ability. The potential regulations of AI-2 quorum sensing (QS) system and activated methyl cycle (AMC) were studied by analyzing the supplementation roles of key circulating substances mediated via luxS, including S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), methionine (Met), homocysteine (Hcy) and 4,5-dihydroxy-2,3-pentanedione (DPD). Growth experiments revealed that the luxS deletion led to certain growth limitations of SHP, which were associated with culture medium and exogenous additives. Meanwhile, the decreased biofilm formation and diminished hydrogen sulfide (H2S) production capacity of SHP were observed after luxS deletion. The relatively lower total volatile base nitrogen (TVB-N) contents and higher sensory scores of fish homogenate with luxS mutant strain inoculation also indicated the weaker spoilage-inducing effects after luxS deletion. However, these deficiencies could be offset with the exogenous supply of circulating substances mentioned above. Our findings suggested that the luxS deletion would reduce the spoilage ability of SHP, which was potentially attributed to the disorder of AMC and AI-2 QS system.

Enhanced synthesis of S-adenosyl-L-methionine through combinatorial metabolic engineering and Bayesian optimization in Saccharomyces cerevisiae.

S-Adenosyl-L-methionine (SAM) is a substrate for many enzyme-catalyzed reactions and provides methyl groups in numerous biological methylations, and thus has vast applications in the agriculture and medical field. Saccharomyces cerevisiae has been engineered as a platform with significant potential for producing SAM, but the current production has room for improvement. Thus, a method that consists of a series of metabolic engineering strategies was established in this study. These strategies included enhancing SAM synthesis, increasing ATP supply, down-regulating SAM metabolism, and down-regulating competing pathway. After combinatorial metabolic engineering, Bayesian optimization was conducted on the obtained strain C262P6S to optimize the fermentation medium. A final yield of 2972.8 mg·L-1 at 36 h with 29.7% of the L-Met conversion rate in the shake flask was achieved, which was 26.3 times higher than that of its parent strain and the highest reported production in the shake flask to date. This paper establishes a feasible foundation for the construction of SAM-producing strains using metabolic engineering strategies and demonstrates the effectiveness of Bayesian optimization in optimizing fermentation medium to enhance the generation of SAM.

Radical S-adenosyl methionine domain-containing 2, a potential target of D-tryptophan in asthma treatment, regulates T helper cell type 1/2 balance.

Asthma is a common chronic respiratory disease. D-tryptophan (D-TRP) can inhibit allergic airway inflammation and T helper cell type 2 (Th2) immune response. RNA-sequencing results have indicated that radical S-adenosyl methionine domain-containing 2 (RSAD2) might be a potential molecular target of D-TRP in asthma treatment. Herein, we established a mouse model of asthma using ovalbumin (OVA) via intraperitoneal injection and inhalational challenge. Gain- and loss-of-function studies of RSAD2 were performed in mice following the intratracheal delivery of lentiviral vectors (3 × 106 TU/mL). Naïve CD-4+ T cells were isolated from the spleen and used to explore the effects of RSAD2 on Th2 cell differentiation. RSAD2 expression was higher in the asthma group than in the control group. RSAD2 knockdown alleviated inflammatory cell infiltration and reduced the number of goblet cells. Low RSAD2 expression decreased the levels of IgE, IL-25, IL-33, and TSLP, and it reduced the number of inflammatory cells in the bronchoalveolar lavage fluid. RSAD2 silencing suppressed Th2-related cytokine levels (such as IL-4, IL-5, and IL-13) and increased Th1-related cytokine levels (such as IFN-γ). Additionally, RSAD2 knockdown inhibited the phosphorylation of JAK1, JAK3, and STAT6, and downregulated GATA-3 expression. RSAD2 overexpression increased inflammatory cell infiltration and mucus secretion in the lung tissues of mice pretreated with D-TRP. D-TRP pretreatment reduced OVA-specific IgE content and IL-4 and IL-5 levels, and it increased the IFN-γ levels; however, RSAD2 overexpression reversed these effects. In conclusion, RSAD2 knockdown can mitigate OVA-induced asthma by regulating the Th2 immune response via JAK/STAT6 pathway inhibition.

Methionine secreted by tumor-associated pericytes supports cancer stem cells in clear cell renal carcinoma.

Here, we identify a subset of vascular pericytes, defined by expression of platelet-derived growth factor receptor beta (PDGFR-ß) and G-protein-coupled receptor 91 (GPR91), that promote tumorigenesis and tyrosine kinase inhibitors (TKIs) resistance by functioning as the primary methionine source for cancer stem cells (CSCs) in clear cell renal cell carcinoma (ccRCC). Tumor-cell-derived succinate binds to GPR91 on pericyte to activate autophagy for methionine production. CSCs use methionine to create stabilizing N6-methyladenosine in ATPase-family-AAA-domain-containing 2 (ATAD2) mRNA, and the resulting ATAD2 protein complexes with SRY-box transcription factor 9 to assemble super enhancers and thereby dictate its target genes that feature prominently in CSCs. Targeting PDGFR-ß+GPR91+ pericytes with specific GRP91 antagonists reduce intratumoral methionine level, eliminate CSCs, and enhance TKIs sensitivity. These results unraveled the mechanisms by which PDGFR-ß+GPR91+ pericytes provide supportive niche for CSCs and could be used to develop targets for treating ccRCC.

Apical papilla stem cell-derived exosomes regulate lipid metabolism and alleviate inflammation in the MCD-induced mouse NASH model.

Stem cells from the apical papilla(SCAPs) exhibit remarkable tissue repair capabilities, demonstrate anti-inflammatory and pro-angiogenic effects, positioning them as promising assets in the realm of regenerative medicine. Recently, the focus has shifted towards exosomes derived from stem cells, perceived as safer alternatives while retaining comparable physiological functions. This study delves into the therapeutic implications of exosomes derived from SCAPs in the methionine-choline-deficient (MCD) diet-induced mice non-alcoholic steatohepatitis (NASH) model. We extracted exosomes from SCAPs. During the last two weeks of the MCD diet, mice were intravenously administered SCAPs-derived exosomes at two distinct concentrations (50 µg/mouse and 100 µg/mouse) biweekly. Thorough examinations of physiological and biochemical indicators were performed to meticulously evaluate the impact of exosomes derived from SCAPs on the advancement of NASH in mice induced by MCD diet. This findings revealed significant reductions in body weight loss and liver damage induced by the MCD diet following exosomes treatment. Moreover, hepatic fat accumulation was notably alleviated. Mechanistically, the treatment with exosomes led to an upregulation of phosphorylated adenosine monophosphate-activated protein kinase (p-AMPK) levels in the liver, enhancing hepatic fatty acid oxidation and transporter gene expression while inhibiting genes associated with fatty acid synthesis. Additionally, exosomes treatment increased the transcription levels of key liver mitochondrial marker proteins and the essential mitochondrial biogenesis factor. Furthermore, the levels of serum inflammatory factors and hepatic tissue inflammatory factor mRNA expression were significantly reduced, likely due to the anti-inflammatory phenotype induced by exosomes in macrophages. The above conclusion suggests that SCAPs-exosomes can improve NASH.