Methionine sulfoxide reductase (Msr) dysfunction in human brain disease

A preliminary metabolomics study of the database for biological samples of schizophrenia among Chinese ethnic minorities

BACKGROUND

Schizophrenia (SCZ) is a profound mental disorder with a multifactorial etiology, including genetics, environmental factors, and demographic influences such as ethnicity and geography. Among these, the studies of SCZ also shows racial and regional differences.

METHODS

We first established a database of biological samples for SCZ in China's ethnic minorities, followed by a serum metabolomic analysis of SCZ patients from various ethnic groups within the same region using the LC-HRMS platform.

RESULTS

Analysis identified 47 metabolites associated with SCZ, with 46 showing significant differences between Miao and Han SCZ patients. These metabolites, primarily fatty acids, amino acids, benzene, and derivatives, are involved in fatty acid metabolism pathways. Notably, L-Carnitine, L-Cystine, Aspartylphenylalanine, and Methionine sulfoxide demonstrated greater diagnostic efficacy in Miao SCZ patients compared to Han SCZ patients.

CONCLUSION

Preliminary findings suggest that there are differences in metabolic levels among SCZ patients of different ethnicities in the same region, offering insights for developing objective diagnostic or therapeutic monitoring strategies that incorporate ethnic considerations of SCZ.

Association of the methionine sulfoxide reductase A rs10903323 gene polymorphism with functional activity and oxidative modification of alpha-1-antitrypsin in COPD patients

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is multi-factorial disorder which results from environmental influences and genetic factors. We aimed to investigate whether methionine sulfoxide reductase A (MSRA) rs10903323 gene polymorphism is associated with COPD development and severity in Serbian adult population.

METHODS

The study included 155 patients with COPD and 134 healthy volunteers. Genotyping was determined performing home-made polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The difference between the inhibitory activities of normal and oxidized Alpha-1-Antitrypsin (A1AT) against elastase and trypsin was used for determination of Oxidized Alpha-1-Antitrypsin (OxyA1AT) (expressed as % and g/L). Functional activity of A1AT was presented as a specific inhibitor activity to elastase (SIA-Elastase, kU/g).

RESULTS

Frequencies of the genotypes AA, AG and GG were 80.0%, 20.0%, 0% in COPD patients and 80.5%, 18.5% and 1.5% in the control group, and there was no significant difference in genotype or allele distributions between groups. Serum level of A1AT (g/L) and OxyA1AT was significantly higher in COPD patients than in the control group, but functional activity of A1AT (SIA-Elastase) was significantly lower in COPD patients than in the control group. In COPD group, increased level of OxyA1AT was present in G allele carriers who were smokers relative to G allele carriers who were not smokers. In the smoker group of patients with severe and very severe COPD (GOLD3+4), significant increase in OxyA1AT level was present in G allele carriers compared to AA homozygotes.

CONCLUSION

These findings suggest that MSRA rs10903323 gene polymorphism is probably not a risk for COPD by itself but could represent a COPD modifier, since minor, G allele, is associated with an increased level of oxidized A1AT, indicating impaired ability of MSRA to repair oxidized A1AT in COPD-smokers, and in severe form of COPD.

Integrated analysis of the association between methionine cycle and risk of moyamoya disease

OBJECTIVE

The role of methionine (Met) cycle in the pathogenesis and progression of cardiovascular and cerebrovascular diseases has been established, but its association with moyamoya disease (MMD) has rarely been studied. This study aimed to analyze the levels of Met cycle-related metabolites and constructed a risk model to explore its association with the risk of MMD.

METHODS

In this prospective study, a total of 302 adult MMD patients and 88 age-matched healthy individuals were consecutively recruited. The serum levels of Met cycle-related metabolites were quantified by liquid chromatography-mass spectrometry (LC-MS). Participants were randomly divided into training set and testing set at a ratio of 1:1. The training set was used to construct the risk score model by LASSO regression. The association between Met cycle-related risk score and the risk of MMD was analyzed using logistic regression and assessed by ROC curves. The testing set was used for validation.

RESULTS

The levels of methionine sulfoxide and homocysteine were significantly increased, while the levels of betaine and choline were significantly decreased in MMD and its subtypes compared to healthy controls (p < 0.05 for all). The training set was used to construct the risk model and the risk score of each participant has been calculated. After adjusting for potential confounders, the risk score was independently associated with the risk of MMD and its subtypes (p < 0.05 for all). We then divided the participants into low-risk and high-risk groups, the high-risk score was significantly associated with the risk of MMD and its subtypes (p < 0.05 for all). The risk scores were further assessed as tertiles, the highest tertile was significantly associated with a higher risk of MMD and its subtypes compared to the lowest (p < 0.05 for all). The results were validated in the testing set.

CONCLUSION

This study has constructed and validated a risk model based on Met cycle-related metabolites, which was independently associated with the risk of MMD and its subtypes. The findings provided a new perspective on the risk evaluation and prevention of MMD.

Decoding DNA sequence-driven evolution of the human brain epigenome at cellular resolution

DNA-based evolutionary comparisons of regulatory genomic elements enable insight into functional changes, overcoming tissue inaccessibility. Here, we harnessed adult and fetal cortex single-cell ATAC-seq datasets to uncover DNA substitutions specific to the human and human-ancestral lineages within apes. We found that fetal microglia identity is evolutionarily divergent in all lineages, whereas other cell types are conserved. Using multiomic datasets, we further identified genes linked to multiple lineage-divergent gene regulatory elements and implicated biological pathways associated with these divergent features. We also uncovered patterns of transcription factor binding site evolution across lineages and identified expansion of bHLH-PAS factor targets in human-hominin lineages, and MEF2 factor targets in the ape lineage. Finally, conserved features were more enriched in brain disease variants, whereas there was no distinct enrichment on the human lineage compared to its ancestral lineages. Our study identifies major evolutionary patterns in the human brain epigenome at cellular resolution.

Association between methionine sulfoxide and risk of moyamoya disease

Objective

Methionine sulfoxide (MetO) has been identified as a risk factor for vascular diseases and was considered as an important indicator of oxidative stress. However, the effects of MetO and its association with moyamoya disease (MMD) remained unclear. Therefore, we performed this study to evaluate the association between serum MetO levels and the risk of MMD and its subtypes.

Methods

We eventually included consecutive 353 MMD patients and 88 healthy controls (HCs) with complete data from September 2020 to December 2021 in our analyzes. Serum levels of MetO were quantified using liquid chromatography-mass spectrometry (LC-MS) analysis. We evaluated the role of MetO in MMD using logistic regression models and confirmed by receiver-operating characteristic (ROC) curves and area under curve (AUC) values.

Results

We found that the levels of MetO were significantly higher in MMD and its subtypes than in HCs (p < 0.001 for all). After adjusting for traditional risk factors, serum MetO levels were significantly associated with the risk of MMD and its subtypes (p < 0.001 for all). We further divided the MetO levels into low and high groups, and the high MetO level was significantly associated with the risk of MMD and its subtypes (p < 0.05 for all). When MetO levels were assessed as quartiles, we found that the third (Q3) and fourth (Q4) MetO quartiles had a significantly increased risk of MMD compared with the lowest quartile (Q3, OR: 2.323, 95%CI: 1.088-4.959, p = 0.029; Q4, OR: 5.559, 95%CI: 2.088-14.805, p = 0.001).

Conclusion

In this study, we found that a high level of serum MetO was associated with an increased risk of MMD and its subtypes. Our study raised a novel perspective on the pathogenesis of MMD and suggested potential therapeutic targets.

Modulating antioxidant systems as a therapeutic approach to retinal degeneration

The human retina is facing a big challenge of reactive oxygen species (ROS) from endogenous and exogenous sources. Excessive ROS can cause damage to DNA, lipids, and proteins, triggering abnormal redox signaling, and ultimately lead to cell death. Thus, oxidative stress has been observed in inherited retinal diseases as a common hallmark. To counteract the detrimental effect of ROS, cells are equipped with various antioxidant defenses. In this review, we will focus on the antioxidant systems in the retina and how they can protect retina from oxidative stress. Both small antioxidants and antioxidant enzymes play a role in ROS removal. Particularly, the thioredoxin and glutaredoxin systems, as the major antioxidant systems in mammalian cells, exert functions in redox signaling regulation via modifying cysteines in proteins. In addition, the thioredoxin-like rod-derived cone viability factor (RdCVFL) and thioredoxin interacting protein (TXNIP) can modulate metabolism in photoreceptors and promote their survival. In conclusion, elevating the antioxidant capacity in retina is a promising therapy to curb the progress of inherited retinal degeneration.

An Intramolecular Charge Transfer-Förster Resonance Energy Transfer Integrated Unimolecular Platform for Two-Photon Ratiometric Fluorescence Sensing of Methionine Sulfoxide Reductases in Live-Neurons and Mouse Brain Tissues

Oxidative stress in organisms is a factor leading to a series of diseases including tumors and neurological disorders, while methionine sulfoxide reductases (Msrs) may provide an antioxidant and self-repair mechanism through redox cycles of methionine residues in proteins. Thus, it is important to understand the crucial role of Msrs in maintaining the redox homeostasis. However, it remains a great challenge for real-time and quantitative monitoring of Msrs in live systems due to the lack of appropriate sensing tools. Herein, a novel unimolecular platform integrating the intramolecular charge transfer (ICT) and Förster resonance energy transfer (FRET) dual mechanisms was successfully developed. By employing the highly specific Msrs-catalyzed reduction from the electron-withdrawing sulfoxide moiety in the probe to an electron-donating sulfide group, a synergistic ICT-FRET activation process was achieved, leading to a ratiometric fluorescence response toward Msrs with high selectivity, sensitivity, and accuracy. Moreover, benefiting from the favorable features, including mitochondria-targeting, near-infrared two-photon excitation, low cytotoxicity, good stability, and biocompatibility, the probe was successfully used for monitoring mitochondrial Msrs levels in live-neurons, and a positively correlated up-regulation of endogenous Msrs levels under O₂^•- stimulation was observed for the first time, confirming a Msrs-involved adaptive antioxidant mechanism in neurons. Furthermore, two-photon microscopic imaging of various regions in Alzheimer's disease (AD) mice brains revealed a down-regulated Msrs levels compared with that in normal brains, especially in the cornuammonis of the hippocampus region, which may in turn lead to an aggravation of AD pathogenesis due to the weakened antioxidant and self-repair capability of neurons.

Impacts of oxidants and antioxidants on the emergence and progression of Alzheimer's disease

The brain shows a high sensitivity to oxidative stress (OS). Thus, the maintenance of homeostasis of the brain regarding the reduction-oxidation (redox) situation is crucial for the regular function of the central nervous systems (CNS). The imbalance between the reactive oxygen species (ROS) and the cellular mechanism might lead to the emergence of OS, causing profound cell death as well as tissue damages and initiating neurodegenerative disorders (NDDs). Characterized by the cytoplasmic growth of neurofibrillary tangles and extracellular β-amyloid plaques, Alzheimer's disease (AD) is a complex NDD that causes dementia in adult life with severe manifestations. Nuclear factor erythroid 2-related factor 2 (NRF2) is a key transcription factor that regulates the functional expression of OS-related genes and the functionality of endogenous antioxidants. In the case of oxidative damage, NRF2 is transferred to the nucleus and attached to the antioxidant response element (ARE) that enhances the sequence to initiate transcription of the cell-protecting genes. This review articulates various mechanisms engaged with the generation of active and reactive species of endogenous and exogenous oxidants and focuses on the antioxidants as a body defense system regarding the NRF2-ARE signaling path in the CNS.

Variability in the antioxidant MSRA gene affects the psychopathology of patients with anorexia nervosa

The objective is to determine whether variability in the MSRA gene, related to obesity and several psychiatric conditions, may be relevant for psychopathological symptoms common in Anorexia Nervosa (AN) and/or for the susceptibility to the disorder. A total of 629 women (233 AN patients and 396 controls) were genotyped for 14 tag-SNPs. Psychometric evaluation was performed with the EDI-2 and SCL-90R questionnaires. Genetic associations were carried out by logistic regression controlling for age and adjusting for multiple comparisons (FDR method). Two tag-SNPs, rs11249969 and rs81442 (with a pairwise r2 value of 0.41), were associated with the global EDI-2 score, which measures EDI-related psychopathology (adjusted FDR-q = 0.02 and 0.04, respectively). Moreover, rs81442 significantly modulated all the scales of the SCL-90R test that evaluates general psychopathology (FDR-q values ranged from 4.1E-04 to 0.011). A sliding-window analysis using adjacent 3-SNP haplotypes revealed a proximal region of the MSRA gene spanning 187.8 Kbp whose variability deeply affected psychopathological symptoms of the AN patients. Depression was the symptom that showed the strongest association with any of the constructed haplotypes (FDR-q = 3.60E-06). No variants were found to be linked to AN risk or anthropometric parameters in patients or controls. Variability in the MSRA gene locus modulates psychopathology often presented by AN patients.

MsrB1 Promotes Proliferation and Invasion of Colorectal Cancer Cells via GSK-3β/β-catenin Signaling Axis

Methionine sulfoxide reductase B1 (MsrB1) can catalyze both free and protein-bound R-methionine sulfoxides (R-MetO) to methionine (Met). It has been reported that MsrB1 plays an important role in the development of HCC and human bone osteosarcoma. However, little is known about the functions of MsrB1 in human colorectal cancer (CRC). Herein, we detected MsrB1 expression level in CRC tissue and cell lines, and investigated the effect of MsrB1 knockdown on CRC phenotypes and possible mechanisms involved in. The results showed that MsrB1 was highly expressed in both CRC tissues and cell lines, and that cell proliferation, migration and invasion were significantly inhibited, but apoptosis was increased after MsrB1 knockdown in colorectal cancer HCT116 and RKO cell lines, compared to control siRNA group. In addition, E-cadherin protein level was increased, vimentin and Snail protein were greatly decreased after knockdown of MsrB1 in cells. Furthermore, pGSK-3β (Ser9) and β-catenin protein levels were reduced, the promoter activity of TCF/LEF construction was inhibited after MsrB1 knockdown in cells, suggesting that GSK-3β/β-catenin signaling axis was involved in the tumorigenesis of CRC. In conclusion, the oncogenic role and related mechanisms of MsrB1 in CRC discovered in our work determined the potential role of MsrB1 as a biomarker and may provide a new target for clinical therapy of CRC.

Nontargeted metabolomics-based mapping urinary metabolic fingerprints after exposure to acrylamide

Acrylamide classified as a probable carcinogen to humans is a high production volume chemical in industrial applications released to aquatic and environmental ecosystems, and also widely found in the thermal processing of starch-rich foods. To gain insight into the urinary metabolomics that may induce physiological responses stimulated by acrylamide, rats were orally administered with a single dose of 13C3-acrylamide (10 mg/kg bw) in the treatment group and urine samples were continuously collected every 2 h during the first 18 h and every 3 h during the period from 18 h to 36 h. A reliable nontargeted screening method for the analysis of urinary metabolomics in rats was developed using ultra-high performance liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry. All metabolites in urine of rats receiving isotope-labeled acrylamide were screened by validated orthogonal partial least squares-discriminant analyses compared to the animals in the control group, while exposure biomarkers were further confirmed according to the characteristic fragmentation rules and time-dependent profiles. Here we identified 2 new specific exposure biomarkers, named N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine-sulfoxide and N-acetyl-S-(2-carboxyl)-L-cysteine, compared to 4 currently acknowledged mercapturic acid adducts of acrylamide. In addition, our findings on analysis of acrylamide metabolic pathway and identification of exposure biomarkers confirmed that acrylamide could significantly affect energy metabolism and amino acid metabolism by the Kyoto Encyclopedia of Genes and Genomes pathway analysis for key metabolites. Homocysteine thiolactone and hypoxanthine may be potential biomarkers for the cardiotoxicity, while methionine sulfoxide, hippuric acid and melatonin may be specifically related to the neurotoxicity. Thus, the current study provided new evidence on the identification of emerging exposure biomarkers and specific signature metabolites related to the toxicity of acrylamide, and shed light on how acrylamide affected energy and amino acid metabolism by further mapping urinary metabolic fingerprints.

Differential Responses of Methionine Sulfoxide Reductases A and B to Anoxia and Oxidative Stress in the Freshwater Turtle Trachemys scripta

Oxidative stress has been acknowledged as a major factor in aging, senescence and neurodegenerative conditions. Mammalian models are susceptible to these stresses following the restoration of oxygen after anoxia; however, some organisms including the freshwater turtle Trachemys scripta can withstand repeated anoxia and reoxygenation without apparent pathology. T. scripta thus provides us with an alternate vertebrate model to investigate physiological mechanisms of neuroprotection. The objective of this study was to investigate the antioxidant methionine sulfoxide reductase system (Msr) in turtle neuronal tissue. We examined brain transcript and protein levels of MsrA and MsrB and examined the potential for the transcription factor FOXO3a to regulate the oxygen-responsive changes in Msr in vitro. We found that Msr mRNA and protein levels are differentially upregulated during anoxia and reoxygenation, and when cells were exposed to chemical oxidative stress. However, while MsrA and MsrB3 levels increased when cell cultures were exposed to chemical oxidative stress, this induction was not enhanced by treatment with epigallocatechin gallate (EGCG), which has previously been shown to enhance FOXO3a levels in the turtle. These results suggest that FOXO3a and Msr protect the cells from oxidative stress through different molecular pathways, and that both the Msr pathway and EGCG may be therapeutic targets to treat diseases related to oxidative damage.

Profiling Dopamine-Induced Oxidized Proteoforms of β-synuclein by Top-Down Mass Spectrometry

The formation of multiple proteoforms by post-translational modifications (PTMs) enables a single protein to acquire distinct functional roles in its biological context. Oxidation of methionine residues (Met) is a common PTM, involved in physiological (e.g., signaling) and pathological (e.g., oxidative stress) states. This PTM typically maps at multiple protein sites, generating a heterogeneous population of proteoforms with specific biophysical and biochemical properties. The identification and quantitation of the variety of oxidized proteoforms originated under a given condition is required to assess the exact molecular nature of the species responsible for the process under investigation. In this work, the binding and oxidation of human β-synuclein (BS) by dopamine (DA) has been explored. Native mass spectrometry (MS) has been employed to analyze the interaction of BS with DA. In a second step, top-down fragmentation of the intact protein from denaturing conditions has been performed to identify and quantify the distinct proteoforms generated by DA-induced oxidation. The analysis of isobaric proteoforms is approached by a combination of electron-transfer dissociation (ETD) at each extent of modification, quantitation of methionine-containing fragments and combinatorial analysis of the fragmentation products by multiple linear regression. This procedure represents a promising approach to systematic assessment of proteoforms variety and their relative abundance. The method can be adapted, in principle, to any protein containing any number of methionine residues, allowing for a full structural characterization of the protein oxidation states.

Unconventional Biocatalytic Approaches to the Synthesis of Chiral Sulfoxides

Sulfoxides are a class of organic compounds that find wide application in medicinal and organic chemistry. Several biocatalytic approaches have been developed to synthesise enantioenriched sulfoxides, mainly by exploiting oxidative enzymes. Recently, the use of reductive enzymes such as Msr and Dms has emerged as a new, alternative method to obtain enantiopure sulfoxides from racemic mixtures. In parallel, novel oxidative approaches, employing nonclassical solvents such as ionic liquids (ILs) and deep eutectic solvents (DESs), have been developed as greener and more sustainable biocatalytic synthetic pathways. This minireview aims highlights the recent advances made in the biocatalytic synthesis of enantioenriched sulfoxides by employing such unconventional approaches.

Oxidative-Antioxidant Imbalance and Impaired Glucose Metabolism in Schizophrenia

Schizophrenia is a neurodevelopmental disorder featuring chronic, complex neuropsychiatric features. The etiology and pathogenesis of schizophrenia are not fully understood. Oxidative-antioxidant imbalance is a potential determinant of schizophrenia. Oxidative, nitrosative, or sulfuric damage to enzymes of glycolysis and tricarboxylic acid cycle, as well as calcium transport and ATP biosynthesis might cause impaired bioenergetics function in the brain. This could explain the initial symptoms, such as the first psychotic episode and mild cognitive impairment. Another concept of the etiopathogenesis of schizophrenia is associated with impaired glucose metabolism and insulin resistance with the activation of the mTOR mitochondrial pathway, which may contribute to impaired neuronal development. Consequently, cognitive processes requiring ATP are compromised and dysfunctions in synaptic transmission lead to neuronal death, preceding changes in key brain areas. This review summarizes the role and mutual interactions of oxidative damage and impaired glucose metabolism as key factors affecting metabolic complications in schizophrenia. These observations may be a premise for novel potential therapeutic targets that will delay not only the onset of first symptoms but also the progression of schizophrenia and its complications.