Analysis of metabolite differences between South Korean and Chinese yellow goosefish (Lophius litulon) using capillary electrophoresis time-of-flight mass spectrometry.

The yellow goosefish is a benthic fish that belongs to the family Lophiidae and order Lophiiformes and is distributed in the Yellow and East China Seas. This study aimed to distinguish between yellow goosefish from different geographical origins by analyzing their metabolites. Capillary electrophoresis time-of-flight mass spectrometry was used to analyze metabolite profiles in the muscle tissues of yellow goosefish to distinguish between Korean and Chinese yellow goosefish. In total, 271 putative metabolites were extracted using 50% acetonitrile in water. Principal component analysis and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to distinguish different geographical origins using the metabolite profiles obtained. The R2 and Q2 values of the OPLS-DA model were 0.856 and 0.695, respectively, indicating that the model was well-fitted and had good predictability. The heat map revealed that nucleic acid and amino compounds differed between the Korean and Chinese fish, and the variable importance in the projection scores obtained from OPLS-DA showed that there were geographical differences in the primary metabolites (5'-methylthioadenosine, adenosine, uridine 5-diphosphate, guanosine 5-diphosphate, urea, homocarnosine, O-acetylcarnitine, cycloleucine, cycloleucine S-adenosylmethionine, S-adenosylhomocysteine, ethanolamine, myo-inositol 1-phosphate), which were identified as potential candidate biomarkers.

Mettl3 Mediated m6A Methylation Involved in Epithelial-Mesenchymal Transition by Targeting SOCS3/STAT3/SNAI1 in Cigarette Smoking-Induced COPD.

Purpose: Persistent inflammation and epithelial-mesenchymal transition are essential pathophysiological processes in chronic obstructive pulmonary disease (COPD) and involve airway remodeling. m6A methylation modification was discovered to play an important role in various diseases. Nevertheless, the regulatory role of m6A methylation has not yet been investigated in cigarette smoking-induced COPD. The study aims to explore the regulatory role of m6A methylation in cigarette smoking-induced COPD. Patients and Methods: In this study, two Gene Expression Omnibus (GEO) datasets were first utilized to analyze the expression profiles of m6A RNA methylation regulators in COPD. We then established a cell model of COPD by exposing human bronchial epithelial cells (HBECs) to cigarette smoke extract (CSE) in vitro and detected the expression of m6A writer Mettl3 and EMT phenotype markers. RNA interference, cycloleucine, RT-qPCR, western blot, MeRIP-sequencing, and cell migration assay were performed to investigate the potential effect of Mettl3 on the EMT process in CSE-induced HBECs. Results: Our results showed that Mettl3 expression was significantly elevated in cigarette smoking-induced COPD patients and in a cellular model of COPD. Furthermore, Mettl3 silence and cycloleucine treatment inhibited the EMT process of HBECs caused by CSE. Mechanically, Mettl3 silence weakens the m6A methylation of SOCS3 mRNA to enhance the protein expression of SOCS3, inhibiting CSE-induced SOCS3/STAT3/SNAI1 signaling and EMT processes in HBECs. Conclusion: Our study inferred that Mettl3-mediated m6A RNA methylation modification modulates CSE-induced EMT by targeting SOCS3 mRNA and ultimately serves as a crucial regulator in the emergence of COPD. This conclusion reinforces the regulatory role of m6A methylation in COPD.

Effects of exogenous glycine betaine and cycloleucine on photosynthetic capacity, amino acid composition, and hormone metabolism in Solanum melongena L.

Although exogenous glycine betaine (GB) and cycloleucine (Cyc) have been reported to affect animal cell metabolism, their effects on plant growth and development have not been studied extensively. Different concentrations of exogenous glycine betaine (20, 40, and 60 mmol L-1) and cycloleucine (10, 20, and 40 mmol L-1), with 0 mmol L-1 as control, were used to investigate the effects of foliar spraying of betaine and cycloleucine on growth, photosynthesis, chlorophyll fluorescence, Calvin cycle pathway, abaxial leaf burr morphology, endogenous hormones, and amino acid content in eggplant. We found that 40 mmol L-1 glycine betaine had the best effect on plant growth and development; it increased the fresh and dry weight of plants, increased the density of abaxial leaf hairs, increased the net photosynthetic rate and Calvin cycle key enzyme activity of leaves, had an elevating effect on chlorophyll fluorescence parameters, increased endogenous indoleacetic acid (IAA) content and decreased abscisic acid (ABA) content, and increased glutamate, serine, aspartate, and phenylalanine contents. However, cycloleucine significantly inhibited plant growth; plant apical dominance disappeared, plant height and dry and fresh weights decreased significantly, the development of abaxial leaf hairs was hindered, the net photosynthetic rate and Calvin cycle key enzyme activities were inhibited, the endogenous hormones IAA and ABA content decreased, and the conversion and utilization of glutamate, arginine, threonine, and glycine were affected. Combined with the experimental results and plant growth phenotypes, 20 mmol L-1 cycloleucine significantly inhibited plant growth. In conclusion, 40 mmol L-1 glycine betaine and 20 mmol L-1 cycloleucine had different regulatory effects on plant growth and development.

Acetaminophen changes the RNA m6A levels and m6A-related proteins expression in IL-1ß-treated chondrocyte cells.

BACKGROUND: Acetaminophen is commonly recommended for the early analgesia of osteoarthritis. However, the molecular mechanism by which it acts remains unknown. The aim of this study is to investigate the effect of acetaminophen on inflammation and extracellular matrix degradation in human chondrocytes, and the possible molecular mechanisms involved in its effect. METHODS: The normal chondrocyte cell line C28/I2 was treated with interleukin-1ß to mimic the inflammatory state. Acetaminophen and the methylation inhibitor (cycloleucine) were used to treat interleukin-1ß-induced C28/I2 cells. The expression of RNA N6-methyladenosine -related proteins was detected by RT-qPCR and western blot. The total RNA N6-methyladenosine level was measured by dot blot analysis and enzyme linked immunosorbent assay. The levels of interleukin-6, interleukin-8 and anti-tumor necrosis factor-α were measured by enzyme linked immunosorbent assay. The extracellular matrix synthesis and degradation were examined by western blot. RESULTS: After interleukin-1ß stimulated C28/I2 cells, the intracellular RNA N6-methyladenosine level increased, and the expression of regulatory proteins also changed, mainly including the increased expression of methyltransferase like 3 and the downregulated expression of AlkB family member 5. The use of cycloleucine inhibited interleukin-1ß-induced inflammation and extracellular matrix degradation by inhibiting RNA N6-methyladenosine modification. In contrast, acetaminophen treatment counteracted interleukin-1ß-induced changes in RNA N6-methyladenosine levels and regulatory protein expression. Furthermore, acetaminophen treatment of interleukin-1ß-induced C28/I2 cells inhibited the secretion of interleukin-6, interleukin-8 and anti-tumor necrosis factor-α, down-regulated the expression of matrix metalloproteinase-13 and Collagen X, and up-regulated the expression of collagen II and aggrecan. In addition, AlkB family member 5 overexpression activated interleukin-1ß-induced chondrocyte viability and suppressed inflammation and extracellular matrix degradation. CONCLUSION: Acetaminophen affects inflammatory factors secretion and extracellular matrix synthesis of human chondrocytes by regulating RNA N6-methyladenosine level and N6-methyladenosine-related protein expression. Stimulation of the normal chondrocyte cell line C28/I2 with the cytokine IL-1ß (10 µM) mimics the inflammatory state in vitro. Acetaminophen (Ace, 50 µg/mL) changes the m6A related proteins expression and the total RNA m6A levels in IL-1ß-treated chondrocyte cells. Furthermore, regulation of RNA m6A levels (by methylation inhibitor Cyc and/or Ace) affects IL-1ß-induced inflammatory cytokines secretion and extracellular matrix synthesis in C28/I2 cells.

Transcriptome analysis of the inhibitory effect of cycloleucine on myogenesis.

N6-Methyladenosine (m6A) has been reported to involve and play an important role in various biological activities but seldom in poultry myogenesis. Cycloleucine usually functions as a nucleic acid methylation inhibitor, the inhibition efficiency of cycloleucine at the m6A level and corresponding dynamic changes of poultry muscle cells remain unknown. In this study, we aim to find out the effect of cycloleucine on the total N6-Methyladenosine level and its molecular mechanism for regulating myogenesis. A total of 745 differentially expressed genes (DEGs) were obtained by 10 mM, 20 mM, and 30 mM of cycloleucine treatment compared with 0 mM treatment. DEGs in 10 mM cycloleucine were significantly enriched in the biological process of skeletal muscle and satellite cell proliferation and differentiation, DEGs in 20 and 30 mM cycloleucine were enriched in some metabolic and biosynthetic processes. The trend analysis showed that 85% of all DEGs were significantly clustered into 4 files, among them 59% DEGs were dose-dependent and 26% were dose-independent, 52% DEGs were in downtrend and 33% DEGs were in uptrend. Also, the cycloleucine treatment could trigger cell cycle arrest in the G1 phase and depress myoblast cell proliferation and inhibit myotube formation. In conclusion, cycloleucine could continuously reduce the m6A level of myoblast cells, depress myoblast cell proliferation and inhibit myotube formation.

Cycloleucine negatively regulates porcine oocyte maturation and embryo development by modulating N6-methyladenosine and histone modifications.

Maturation of oocytes and early embryo development are regulated precisely by numerous factors at transcriptional and posttranslational levels through precise mechanisms. N6-methyladenosine (m6A) is the most common modification in mRNA which regulates RNA metabolism and gene expression. However, the role of RNA m6A on porcine oocyte maturation and early embryogenesis is largely unknown. Here, we found that oocytes treated with cycloleucine (CL), an RNA m6A inhibitor, express impaired cumulus expansion, increased production of reactive oxygen species (ROS) in the mitochondria, and delayed maturation of oocytes by disrupting spindle organization and chromosome alignment. Also, CL halted the development of embryos at the 4-cell stage and resulted in low-quality blastocysts. Furthermore, CL treatment decreased the RNA m6A, H3K4me3, and H3K9me3 levels, but increased the acetylation level of H4K16 during parthenogenetic embryonic development in pigs. Single-cell RNA-seq (scRNA-seq) analysis further revealed that CL treatment dramatically up-regulated the expression of metabolism-related genes (SLC16A1, and MAIG3 etc.) and maternal related genes, including BTG4, WEE2, and BMP15 among others, at the blastocyst stage. Taken together, inhibition of RNA m6A by CL impaired meiosis of oocytes and early embryonic development of porcine via RNA m6A methylation, histone modifications, and altering the expression of metabolism-related genes in blastocysts.

Molecular Umbrella as a Nanocarrier for Antifungals.

A molecular umbrella composed of two O-sulfated cholic acid residues was applied for the construction of conjugates with cispentacin, containing a "trimethyl lock" (TML) or o-dithiobenzylcarbamoyl moiety as a cleavable linker. Three out of five conjugates demonstrated antifungal in vitro activity against C. albicans and C. glabrata but not against C. krusei, with MIC90 values in the 0.22-0.99 mM range and were not hemolytic. Antifungal activity of the most active conjugate 24c, containing the TML-pimelate linker, was comparable to that of intact cispentacin. A structural analogue of 24c, containing the Nap-NH2 fluorescent probe, was accumulated in Candida cells, and TML-containing conjugates were cleaved in cell-free extract of C. albicans cells. These results suggest that a molecular umbrella can be successfully applied as a nanocarrier for the construction of cleavable antifungal conjugates.

Towards Foldameric Miniproteins: A Helix-Turn-Helix Motif.

Numerous beta-amino acid containing peptides forming secondary structures have been already described, however the design of higher-order structures remains poorly explored. The methodology allowing construction of sequence patterns containing few rigid secondary element was proposed and experimentally validated. On the basis of 9/10/9/12-helix containing cis-2-aminocyclopentanecarboxylic acid (cis-ACPC) residues arranged in an ααßß sequence pattern, a conformationally stable helix-turn-helix structure was designed. The connection between two helices was also constructed using cis-ACPC residues. Five examples of designed peptides were obtained and analyzed using circular dichroism and nuclear magnetic resonance spectroscopy, which confirmed the assumed way of folding. The NMR structure was calculated for the peptide with the highest number of non-sequential contacts.

Triple-Methyl Blockade With Recombinant Methioninase, Cycloleucine, and Azacitidine Arrests a Pancreatic Cancer Patient-Derived Orthotopic Xenograft Model.

OBJECTIVES: Methionine addiction is a fundamental and general hallmark of cancer caused by enhanced methyl flux. In the present study, we effected a novel methionine-methylation blockade to target a patient-derived orthotopic xenograft model of pancreatic cancer. METHODS: The pancreatic cancer patient-derived orthotopic xenograft mouse models were randomized into 6 groups of 8 mice each and treated for 2 weeks: untreated control; azacitidine; oral recombinant methioninase (o-rMETase); o-rMETase plus cycloleucine; o-rMETase plus cycloleucine plus azacitidine (triple-methyl blockade therapy); and gemcitabine (positive control). RESULTS: Triple-methyl blockade therapy arrested tumor growth (mean relative tumor volume, 1.03 [standard deviation, 0.36]) and was significantly more effective compared with azacitidine (P = 0.0001); o-rMETase (P = 0.007); or o-rMETase plus cycloleucine (P = 0.04). Gemcitabine alone also inhibited but did not arrest tumor growth (mean relative tumor volume, 1.50 [standard deviation, 0.30]). The percentage of cancer cells that were negative for 5-methylcytosine staining in immunohistochemistry, indicating reduction of DNA methylation, increased with triple-methyl blockade therapy (37.5%), compared with gemcitabine (1.8%); o-rMETase (2.8%); azacitidine (9.0%); or o-rMETase plus cycloleucine (10.6%). CONCLUSIONS: This new concept of triple-methyl blockade therapy has clinical potential for pancreatic cancer, which is currently a recalcitrant disease.

Systematic 'foldamerization' of peptide inhibiting p53-MDM2/X interactions by the incorporation of trans- or cis-2-aminocyclopentanecarboxylic acid residues.

A 'foldamerization' strategy for the discovery of biologically active peptide is evaluated using as an example the peptides that inhibit the p53-MDM2/X interactions. Application of a peptide scan with two constrained ß-residue of trans and cis stereochemistry indicated a substitution pattern that leads to active molecules with enhanced conformational stability and high resistance to proteolysis. This procedure led to the discovery of a peptide that showed subnanomolar inhibition of the p53-MDM2 interaction (Ki = 0.4 nM) with resistance to proteolysis enhanced by ca. two orders of magnitude. Crystallographic analysis and molecular modelling allowed for understanding of these peptide-protein interactions at the molecular level.

Effects of Cycloleucine in the Nucleus Accumbens Septi on the Elevated plus Maze Test in Rats.

INTRODUCTION: In recent years, an important number of studies have emphasized the psychopharmacological actions of cycloleucine (1-aminocyclopentanecarboxylic acid) acting on the NR1 subunit (glycine allosteric site) of NMDA (N-methyl-D-aspartic acid) receptor. We studied the effects of its injection in an anxiety test. METHODS: The elevated plus maze test was used. Male rats bilaterally cannulated into the nucleus accumbens septi (NAS) were employed. Rats were divided into 5 groups that received either 1 µL injections of saline or cycloleucine (0.5, 1, 2, or 4 µg) 15 min before testing. RESULTS: Time spent in the open arm was significantly increased by cycloleucine treatment with all doses (1 and 2 µg, p < 0.05; 0.5 and 4 µg, p < 0.01), like number of extreme arrivals (0.5 and 1 µg, p < 0.05; 2 µg, p < 0.01; and 4 µg, p < 0.001). Open arm entries were increased by the highest dose only (4 µg, p < 0.01). DISCUSSION/CONCLUSION: Present results show no difference between all doses in the time spent in the open arm, suggesting an indirect, noncompetitive action of the drug. The increase in extreme arrivals and open arm entries suggests a dose influence in these parameters. We conclude that cycloleucine influence on the NMDA receptors within NAS leads to anxiolytic-like effects and behavioral disinhibition, which once more confirms the involvement of NAS in anxiety processing.

Synthesis, in vitro biological activity and docking of new analogs of BIM-23052 containing unnatural amino acids.

Somatostatin (SST) is an endogenous cyclic tetradecapeptide hormone that exerts multiple biological activities via a family of five receptors. BIM-23052 (DC-23-99) D-Phe-Phe-Phe-D-Trp-Lys-Thr-Phe-Thr-NH2 is a linear SST analog with established in vitro GH-inhibitory activity and high affinity to sstr5, sstr3 and sstr2. The different SSTR subtypes are expressed in different tissues and in some tumor cells. Based on this finding, a series of new analogs of BIM-23052 with expected antitumor activity have been synthesized. The Thr at position 6 in BIM-23052 was replaced by the conformationally hindered Tle, Aib, Ac5c and Ac6c of the new analogs. The peptides were synthesized by standard solid-phase peptide chemistry methods, Fmoc strategy. The cytotoxic effects of the compounds were tested in vitro against a panel of tumor cell lines: HT-29, MDA-MB-23, Hep-G2, HeLa and the normal human diploid cell line Lep-3. All five somatostatin receptor subtypes were modeled and docking was performed to determine the binding affinity of the analogs. The new peptides exhibited different concentration-dependent antiproliferative effect on the tumor cell lines after 24 h of treatment. The compound 3B (Aib6) demonstrated the most pronounced antiproliferative effects on HepG-2 cells with the IC50 = 0.01349 nM. Docking confirmed that all compounds bind well to SST receptors with preference to sstr3 and sstr5, which is most probably the reason for the observed biological effects.

Identification of the Amipurimycin Gene Cluster Yields Insight into the Biosynthesis of C9 Sugar Nucleoside Antibiotics.

Feeding studies indicate a possible synthetic pattern for the N-terminal cis-aminocyclopentane carboxylic acid (ACPC) and suggest an unusual source of the high-carbon sugar skeleton of amipurimycin (APM). The biosynthetic gene cluster of APM was identified and confirmed by in vivo experiments. A C9 core intermediate was discovered from null mutants of ACPC pathway, and an ATP-grasp enzyme (ApmA8) was reconstituted in vitro for ACPC loading. Our observations allow a first proposal of the APM biosynthetic pathway.

Ablation of TRPV1 Elevates Nocturnal Blood Pressure in Western Diet-fed Mice.

BACKGROUND: This study tested the hypothesis that genetically ablation of transient receptor potential vanilloid type 1 (TRPV1) exacerbates impairment of baroreflex in mice fed a western diet (WD) and leads to distinct diurnal and nocturnal blood pressure patterns. METHODS: TRPV1 gene knockout (TRPV1-/-) and wild-type (WT) mice were given a WD or normal diet (CON) for 4 months. RESULTS: Capsaicin, a selective TRPV1 agonist, increased ipsilateral afferent renal nerve activity in WT but not TRPV1-/- mice. The sensitivity of renal sympathetic nerve activity and heart rate responses to baroreflex were reduced in TRPV1-/--CON and WT-WD and further decreased in TRPV1-/--WD compared to the WT-CON group. Urinary norepinephrine and serum insulin and leptin at day and night were increased in WT-WD and TRPV1-/--WD, with further elevation at night in TRPV1-/--WD. WD intake increased leptin, IL-6, and TNF-α in adipose tissue, and TNF-α antagonist III, R-7050, decreased leptin in TRPV1-/--WD. The urinary albumin level was higher in TRPV1-/--WD than WT-WD. Blood pressure was not different during daytime among all groups, but increased at night in the TRPV1-/--WD group compared with other groups. CONCLUSIONS: TRPV1 ablation leads to elevated nocturnal but not diurnal blood pressure, which is probably attributed to further enhancement of sympathetic drives at night.

Reduced nucleic acid methylation impairs meiotic maturation and developmental potency of pig oocytes.

Oocyte meiosis is a complex process coordinated by multiple endocrinal and molecular circuits. Recently, N6-methyladenosine (m6A) epigenetic modification on RNA is revealed to be important for meiotic maturation. However, the molecular mechanism of how m6A modification exerts its effect on oocyte maturation is largely unknown. Here, we showed that endogenous m6A writers (Mettl3 and Wtap) and eraser (Fto) elevated their transcript levels during meiotic maturation of pig oocytes. From germinal vesicle (GV) to metaphase II (MII) stages, global m6A level significantly increased, and existed mostly in ooplasm. Methyl donor (betaine, 16 mM) treatment of porcine cumulus-oocyte complexes (COCs) during in vitro maturation (IVM) significantly boosted nucleic acid m6A level within oocytes, but unchanged meiotic process and oocyte subsequent development. By contrast, methylation inhibitor (cycloleucine, 20 mM) reduced nucleic acid m6A level, and significantly decreased the germinal vesicle breakdown (GVBD) rate, the extrusion rate of the first polar body, and the cleavage and blastocyst rates of parthenotes. In addition, in cycloleucine-treated oocytes Wtap increased but Lin28 decreased their abundances significantly, along with the higher incidence of spindle defects and chromosome misalignment. Furthermore, pT161-CDK1 protein level in pig oocytes was confirmed to be decreased after cycloleucine treatment for 24 h. Taken together, chemical induced reduction of nucleic acid m6A methylation during pig oocyte meiosis could impair meiotic maturation and subsequent development potency, possibly through down-regulating pluripotency marker Lin28 mRNA abundance and disturbing MPF-regulated chromosome/spindle organization.

Insights into the structural features and stability of peptide nucleic acid with a D-prolyl-2-aminocyclopentane carboxylic acid backbone that binds to DNA and RNA.

Peptide nucleic acid (PNA) is a powerful biomolecule with a wide variety of important applications. In this work, the molecular structures and binding affinity of PNA with a D-prolyl-2-aminocyclopentane carboxylic acid backbone (acpcPNA) that binds to both DNA and RNA were studied using molecular dynamics simulations. The simulated structures of acpcPNA-DNA and acpcPNA-RNA duplexes more closely resembled the typical structures of B-DNA and A-RNA than the corresponding duplexes of aegPNA. The calculated binding free energies are in good agreement with the experimental results that the acpcPNA-DNA duplex is more stable than the acpcPNA-RNA duplex regardless of the base sequences. The results provide further insights in the relationship between structure and stability of this unique PNA system.

Environmental Effects Determine the Structure of Potential ß-Amino Acid Based Foldamers.

This work shows that hybrid peptides formed by alternating trans-2-aminocyclopentanecarboxylic acid (trans-ACPC) and trans-2-aminocyclohexanecarboxylic acid (trans-ACHC) do not fold in the solvents typically used in the study of their homo-oligomers. Only when the peptides are assayed in SDS micelles are the predicted helical structures obtained. This indicates that the environment could play an equally important role (as the backbone stereochemistry) in determining their fold, possibly by providing a sequestered environment.

FTO reduces mitochondria and promotes hepatic fat accumulation through RNA demethylation.

Fat mass and obesity-associated protein (FTO) is a RNA demethylase, whether FTO regulates fat metabolism through its demethylation is unclear. The results of this study confirmed that N6-methyladenosine (m6 A) is associated with fat accumulation both in vivo and in vitro. The data showed that FTO down-regulated m6 A levels, decreased mitochondrial content, and increased triglyceride (TG) deposition. However, an FTO (R316A) mutant lacking demethylation activity could not regulate mitochondria and TG content, indicating that FTO affects mitochondrial content and fat metabolism by modulating m6 A levels in hepatocytes. In addition, the regulatory roles of cycloleucine (methylation inhibitor) and betaine (methyl donor) could regulate m6 A levels and fat deposition. This work clarified that the demethylation function of FTO plays an essential role in the fat metabolism of hepatocytes and links the epigenetic modification of RNA with fat deposition, thereby providing a new target (m6 A) for regulation of hepatic fat metabolism.

Evaluation of ß-Amino Acid Replacements in Protein Loops: Effects on Conformational Stability and Structure.

ß-Amino acids have a backbone that is expanded by one carbon atom relative to α-amino acids, and ß residues have been investigated as subunits in protein-like molecules that adopt discrete and predictable conformations. Two classes of ß residue have been widely explored in the context of generating α-helix-like conformations: ß3 -amino acids, which are homologous to α-amino acids and bear a side chain on the backbone carbon adjacent to nitrogen, and residues constrained by a five-membered ring, such the one derived from trans-2-aminocyclopentanecarboxylic acid (ACPC). Substitution of α residues with their ß3  homologues within an α-helix-forming sequence generally causes a decrease in conformational stability. Use of a ring-constrained ß residue, however, can offset the destabilizing effect of αâ†’ß substitution. Here we extend the study of αâ†’ß substitutions, involving both ß3 and ACPC residues, to short loops within a small tertiary motif. We start from previously reported variants of the Pin1 WW domain that contain a two-, three-, or four-residue ß-hairpin loop, and we evaluate αâ†’ß replacements at each loop position for each variant. By referral to the ϕ,ψ angles of the native structure, one can choose a stereochemically appropriate ACPC residue. Use of such logically chosen ACPC residues enhances conformational stability in several cases. Crystal structures of three ß-containing Pin1 WW domain variants show that a native-like tertiary structure is maintained in each case.

Serine alleviates oxidative stress via supporting glutathione synthesis and methionine cycle in mice.

SCOPE: Serine lies at the central node linking biosynthetic flux from glycolysis to glutathione synthesis and one-carbon metabolic cycle which are closely related to antioxidant capacity. The present study was conducted to determine the effects of serine supplementation on oxidative stress and its relative mechanisms. METHODS AND RESULTS: Diquat treatment was performed to induce oxidative stress in mice and primary hepatocytes. The results showed that hepatic glutathione anti-oxidant systems were impaired and reactive oxygen species and homocysteine were increased in diquat-induced mice and hepatocytes, while such disadvantageous changes were diminished by serine supplementation both in vivo and in vitro. However, when cystathionine ß-synthase expression was inhibited by interference RNA in hepatocytes, the effects of serine supplementation on the improvement of glutathione synthesis and the alleviation of oxidative stress were diminished. Moreover, when hepatocytes were treated with cycloleucine, an inhibitor of methionine adenosyltransferase, the effects of serine supplementation on the improvement of methionine cycle and the alleviation of DNA hypomethylation and oxidative stress were also diminished. CONCLUSION: Our results indicated that serine supplementation alleviated oxidative stress via supporting glutathione synthesis and methionine cycle, mostly by condensing with homocysteine to synthesize cysteine and providing one-carbon units for homocysteine remethylation.