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Gastrointestinal (GI) sequelae, such as vomiting, hyperacidity, dysphagia, dysmotility, and diarrhea, are nearly universal among patients with nephropathic cystinosis. These complications result from disease processes (e.g., kidney disease, cystine crystal accumulation in the GI tract) and side effects of treatments (e.g., cysteamine, immunosuppressive therapy). GI involvement can negatively impact patient well-being and jeopardize disease outcomes by compromising drug absorption and patient adherence to the strict treatment regimen required to manage cystinosis. Given improved life expectancy due to advances in kidney transplantation and the transformative impact of cystine-depleting therapy, nephrologists are increasingly focused on addressing extra-renal complications and quality of life in patients with cystinosis. However, there is a lack of clinical data and guidance to inform GI-related monitoring, interventions, and referrals by nephrologists. Various publications have examined the prevalence and pathophysiology of selected GI complications in cystinosis, but none have summarized the full picture or provided guidance based on the literature and expert experience. We aim to comprehensively review GI sequelae associated with cystinosis and its treatments and to discuss approaches for monitoring and managing these complications, including the involvement of gastroenterology and other disciplines. [ABSTRACT FROM AUTHOR]

Abstract Background The metabolic reprogramming of amino acids is critical for cancer cell growth and survival. Notably, intracellular accumulation of cysteine is often observed in various cancers, suggesting its potential role in alleviating the oxidative stress associated with rapid proliferation. The liver is the primary organ for cysteine biosynthesis, but much remains unknown about the metabolic alterations of cysteine and their mechanisms in hepatocellular carcinoma cells. Methods RNA-seq data from patients with hepatocarcinoma were analyzed using the TNMplot database. The underlying mechanism of the oncogenic alteration of cysteine metabolism was studied in mice implanted with BNL 1ME A.7 R.1 hepatocarcinoma. Results Database analysis of patients with hepatocellular carcinoma revealed that the expression of enzymes involved in de novo cysteine synthesis was down-regulated accompanying with increased expression of the cystine uptake transporter xCT. Similar alterations in gene expression have also been observed in a syngeneic mouse model of hepatocarcinoma. The enhanced expression of DNA methyltransferase in murine hepatocarcinoma cells caused methylation of the upstream regions of cysteine synthesis genes, thereby repressing their expression. Conversely, suppression of de novo cysteine synthesis in healthy liver cells induced xCT expression by up-regulating the oxidative-stress response factor NRF2, indicating that reduced de novo cysteine synthesis repulsively increases cystine uptake via enhanced xCT expression, leading to intracellular cysteine accumulation. Furthermore, the pharmacological inhibition of xCT activity decreased intracellular cysteine levels and suppressed hepatocarcinoma tumor growth in mice. Conclusions Our findings indicate an underlying mechanism of the oncogenic alteration of cysteine metabolism in hepatocarcinoma and highlight the efficacy of alteration of cysteine metabolism as a viable therapeutic target in cancer.

Background: The metabolic reprogramming of amino acids is critical for cancer cell growth and survival. Notably, intracellular accumulation of cysteine is often observed in various cancers, suggesting its potential role in alleviating the oxidative stress associated with rapid proliferation. The liver is the primary organ for cysteine biosynthesis, but much remains unknown about the metabolic alterations of cysteine and their mechanisms in hepatocellular carcinoma cells. Methods: RNA-seq data from patients with hepatocarcinoma were analyzed using the TNMplot database. The underlying mechanism of the oncogenic alteration of cysteine metabolism was studied in mice implanted with BNL 1ME A.7 R.1 hepatocarcinoma. Results: Database analysis of patients with hepatocellular carcinoma revealed that the expression of enzymes involved in de novo cysteine synthesis was down-regulated accompanying with increased expression of the cystine uptake transporter xCT. Similar alterations in gene expression have also been observed in a syngeneic mouse model of hepatocarcinoma. The enhanced expression of DNA methyltransferase in murine hepatocarcinoma cells caused methylation of the upstream regions of cysteine synthesis genes, thereby repressing their expression. Conversely, suppression of de novo cysteine synthesis in healthy liver cells induced xCT expression by up-regulating the oxidative-stress response factor NRF2, indicating that reduced de novo cysteine synthesis repulsively increases cystine uptake via enhanced xCT expression, leading to intracellular cysteine accumulation. Furthermore, the pharmacological inhibition of xCT activity decreased intracellular cysteine levels and suppressed hepatocarcinoma tumor growth in mice. Conclusions: Our findings indicate an underlying mechanism of the oncogenic alteration of cysteine metabolism in hepatocarcinoma and highlight the efficacy of alteration of cysteine metabolism as a viable therapeutic target in cancer. [ABSTRACT FROM AUTHOR]

Cystinosis is a rare autosomal recessive disease with an incidence 1 per 100,000–200,000 live births. It is caused by pathogenic variants of the cystinosin (CTNS) gene that lead to impaired cystine transport from lysosomes to cystosol, resulting in cystine accumulation in lysosomes and subsequent cellular dysfunction. The initial manifestation, cystine accumulation in proximal tubular cells (PTCs), causes renal Fanconi syndrome, which presents with proximal renal tubular acidosis and generalized dysfunction of the proximal tubule, including the presence of polyuria, glycosuria, phosphaturia, aminoaciduria, tubular proteinuria, growth retardation, and rickets. Eventually, glomerular involvement, glomerular proteinuria, focal segmental glomerulosclerosis (FSGS), and progression to kidney failure occur. Although the kidneys are the first organs affected, and play a key role in morbidity and mortality, extrarenal multiorgan involvement can occur in patients with cystinosis, which is seen not only in adults but in early ages in untreated patients, patients with insufficient treatment, and in those that don't comply with treatment. The treatment of cystinosis consists of supportive treatment for Fanconi syndrome, and specific lifelong cystine-depleting therapy using oral cysteamine. There is strong evidence that as early as possible, initiation and ongoing appropriate therapy with cysteamine are essential for delaying the progression to kidney failure, end-organ damage, and extrarenal involvement. The present review aimed to evaluate the extra renal complications of cystinosis. [ABSTRACT FROM AUTHOR]

In the initial stages of Alopecia Areata (AA), the predominance of hair breakage or exclamation mark hairs serves as vital indicators of disease activity. These signs are non-invasive and are commonly employed in dermatoscopic examinations. Despite their clinical salience, the underlying etiology precipitating this hair breakage remains largely uncharted territory. Our exhaustive review of the existing literature points to a pivotal role for cysteine—a key amino acid central to hair growth—in these mechanisms. This review will probe and deliberate upon the implications of aberrant cysteine metabolism in the pathogenesis of AA. It will examine the potential intersections of cysteine metabolism with autophagy, ferroptosis, immunity, and psychiatric manifestations associated with AA. Such exploration could illuminate new facets of the disease's pathophysiology, potentially paving the way for innovative therapeutic strategies. [ABSTRACT FROM AUTHOR]

Background: Secreted protein acidic and rich in cysteine (SPARC) has been shown to modulate aggressive behavior in several benign and malignant tumors. Little is known about SPARC expression in odontogenic keratocyst (OKC), an odontogenic cyst with an aggressive nature. To the best of our knowledge, only one study has been investigated the expression of this protein in OKCs. This study aimed to characterize SPARC expression in OKCs. Additionally, to determine whether SPARC is associated with aggressive behavior in OKCs, SPARC expression in OKCs was compared with radicular cysts (RCs), dentigerous cysts (DCs) and calcifying odontogenic cysts (COCs). These odontogenic cysts showed no or less aggressive behavior. Methods: SPARC expression was evaluated in 38 OKCs, 39 RCs, 35 DCs and 14 COCs using immunohistochemistry. The percentages of positive cells and the intensities of immunostaining in the epithelial lining and the cystic wall were evaluated and scored. Results: Generally, OKCs showed similar staining patterns to RCs, DCs and COCs. In the epithelial lining, SPARC was not detected, except for ghost cells in all COCs. In the cystic wall, the majority of positive cells were fibroblasts. Compared between 4 groups of odontogenic cysts, SPARC expression in OKCs was significantly higher than those of RCs (P < 0.001), DCs (P < 0.001) and COCs (P = 0.001). Conclusions: A significant increase of SPARC expression in OKCs compared with RCs, DCs and COCs suggests that SPARC may play a role in the aggressive behavior of OKCs. [ABSTRACT FROM AUTHOR]

Background: Osteoarthritis (OA) is a chronic and low-grade inflammatory disease associated with metabolism disorder and multiple cell death types in the synovial tissues. Sulfur metabolism has not been studied in OA. Methods: First, we calculated the single sample gene set enrichment analysis score of sulfur metabolism-associated annotations (i.e., cysteine metabolism process, regulation of sulfur metabolism process, and disulfidptosis) between healthy and synovial samples from patients with OA. Sulfur metabolism-related differentially expressed genes (DEGs) were analyzed in OA. Least absolute shrinkage and selection operator COX regression were used to identify the sulfur metabolism-associated gene signature for diagnosing OA. Correlation and immune cell deconvolution analyses were used to explore the correlated functions and cell specificity of the signature gene, TM9SF2. TM9SF2's effect on the phagocytosis of macrophages M2 was analyzed by coculturing macrophages with IgG-coated beads or apoptotic Jurkat cells. Results: A diagnostic six gene signature (i.e., MTHFD1, PDK4, TM9SF2, POU4F1, HOXA2, NCKAP1) was identified based on the ten DEGs, validated using GSE12021 and GSE1919 datasets. TM9SF2 was upregulated in the synovial tissues of OA at both mRNA and protein levels. The relationship between TM9SF2 and several functional annotations, such as antigen processing and presentation, lysosome, phagosome, Fcγ-mediated phagocytosis, and tyrosine metabolism, was identified. TM9SF2 and macrophages M2 were significantly correlated. After silencing TM9SF2 in THP-1-derived macrophages M2, a significantly reduced phagocytosis and attenuated activation of PLC-γ1 were observed. Conclusion: A sulfur metabolism-associated six-gene signature for OA diagnosis was constructed and upregulation of the phagocytosis-associated gene, TM9SF2, was identified. The findings are expected to deepen our understanding of the molecular mechanism underlying OA development and be used as potential therapeutic targets. [ABSTRACT FROM AUTHOR]

Lung cancer is a lethal disease with no truly efficient therapeutic management despite the progresses, and metabolic profiling can be a way of stratifying patients who may benefit from new therapies. The present study is dedicated to profiling cysteine metabolic pathways in NSCLC cell lines and tumor samples. This was carried out by analyzing hydrogen sulfide (H2S) and ATP levels, examining mRNA and protein expression patterns of cysteine catabolic enzymes and transporters, and conducting metabolomics analysis using nuclear magnetic resonance (NMR) spectroscopy. Selenium–chrysin (SeChry) was tested as a therapeutic alternative with the aim of having an effect on cysteine catabolism and showed promising results. NSCLC cell lines presented different cysteine metabolic patterns, with A549 and H292 presenting a higher reliance on cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) to maintain H2S levels, while the PC-9 cell line presented an adaptive behavior based on the use of mercaptopyruvate sulfurtransferase (MST) and cysteine dioxygenase (CDO1), both contributing to the role of cysteine as a pyruvate source. The analyses of human lung tumor samples corroborated this variability in profiles, meaning that the expression of certain genes may be informative in defining prognosis and new targets. Heterogeneity points out individual profiles, and the identification of new targets among metabolic players is a step forward in cancer management toward personalized medicine. [ABSTRACT FROM AUTHOR]

Simple Summary: The expression of the cysteine–glutamate cotransporter, system xc−, is increased in cancer cells across many cancer types. Imaging system xc− provides new insights into tumour behaviour. The radiotracer (4S)-4-(3-[18F]Fluoropropyl)-L-glutamic acid (18F-FSPG) is specifically transported by system xc−, allowing for a non-invasive method of measuring this transporter's activity. This review summarises the data available on the use of 18F-FSPG in human cancer patients, exploring its advantages and disadvantages, and suggests possible future uses of 18F-FSPG in the assessment of early treatment response and treatment resistance. System xc− is upregulated in cancer cells and can be imaged using novel radiotracers, most commonly with (4S)-4-(3-[18F]fluoropropyl)-L-glutamic acid (18F-FSPG). The aim of this review was to summarise the use of 18F-FSPG in humans, explore the benefits and limitations of 18F-FSPG, and assess the potential for further use of 18F-FSPG in cancer patients. To date, ten papers have described the use of 18F-FSPG in human cancers. These studies involved small numbers of patients (range 1–26) and assessed the use of 18F-FSPG as a general oncological diagnostic agent across different cancer types. These clinical trials were contrasting in their findings, limiting the scope of 18F-FSPG PET/CT as a purely diagnostic agent, primarily due to heterogeneity of 18F-FSPG retention both between cancer types and patients. Despite these limitations, a potential further application for 18F-FSPG is in the assessment of early treatment response and prediction of treatment resistance. Animal models of cancer have shown that changes in 18F-FSPG retention following effective therapy precede glycolytic changes, as indicated by 18F-FDG, and changes in tumour volume, as measured by CT. If these results could be replicated in human clinical trials, imaging with 18F-FSPG PET/CT would offer an exciting route towards addressing the currently unmet clinical needs of treatment resistance prediction and early imaging assessment of therapy response. [ABSTRACT FROM AUTHOR]

In plastids, conversion of light energy into ATP relies on cytochrome f, a key electron carrier with a heme covalently attached to a CXXCH motif. Covalent heme attachment requires reduction of the disulfide-bonded CXXCH by CCS5 and CCS4. CCS5 receives electrons from the oxidoreductase CCDA, while CCS4 is a protein of unknown function. In Chlamydomonas reinhardtii, loss of CCS4 or CCS5 yields a partial cytochrome f assembly defect. Here, we report that the ccs4ccs5 double mutant displays a synthetic photosynthetic defect characterized by a complete loss of holocytochrome f assembly. This defect is chemically corrected by reducing agents, confirming the placement of CCS4 and CCS5 in a reducing pathway. CCS4-like proteins occur in the green lineage, and we show that HCF153, a distant ortholog from Arabidopsis thaliana, can substitute for Chlamydomonas CCS4. Dominant suppressor mutations mapping to the CCS4 gene were identified in photosynthetic revertants of the ccs4ccs5 mutants. The suppressor mutations yield changes in the stroma-facing domain of CCS4 that restore holocytochrome f assembly above the residual levels detected in ccs5. Because the CCDA protein accumulation is decreased specifically in the ccs4 mutant, we hypothesize the suppressor mutations enhance the supply of reducing power through CCDA in the absence of CCS5. We discuss the operation of a CCS5-dependent and a CCS5-independent pathway controlling the redox status of the heme-binding cysteines of apocytochrome f. Reduction of a disulfide formed between the heme-linking cysteines of apoforms of c-type cytochromes in the thylakoid lumen requires the provision of reducing power from stroma to apocytochrome c via thiol-disulfide exchange. Reducing power is supplied through two different pathways, pathways 1 and 2, with CCDA and CCS4 being common components to both pathways. In pathway 1, CCS5 directly reduces the disulfide-bonded heme-binding site. In pathway 2, one or several yet-to-be identified protein(s) (X) reduce(s) the disulfide. CCS4 functions in stabilizing CCDA. In the absence of CCS5, gain-offunction mutations altering the C terminus of CCS4 enhance the delivery of reducing power via CCDA to the unknown reductase(s) (X), underscoring the functional importance of the soluble domain in CCS4 (indicated by a yellow star). This domain might act by recruiting the stromal reductant to CCDA or control the reactivity of the redox-active cysteines in CCDA by providing an ideal chemical microenvironment for efficient thiol-disulfide exchange. [ABSTRACT FROM AUTHOR]

Objective We describe a family with a novel mutation in the TNF Receptor Superfamily Member 1A (TNFRSF1A) gene causing TNF receptor–associated periodic syndrome (TRAPS) with renal AA amyloidosis. Methods Case series of affected family members. We further investigated the plasma metabolome of these patients in comparison with healthy controls using mass spectrometry. Results In all symptomatic family members, we detected the previously undescribed variant c.332A>G (p.Q111R) in the TNFRSF1A gene. Canakinumab proved an effective treatment option leading to remission in all treated patients. One patient with suspected renal amyloidosis showed near normalization of proteinuria under treatment. Analysis of the metabolome revealed 31 metabolic compounds to be upregulated and 35 compounds to be downregulated compared with healthy controls. The most dysregulated metabolites belonged to pathways identified as arginine biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis, and cysteine and methionine metabolism. Interestingly, the metabolic changes observed in all three TRAPS patients seemed independent of treatment with canakinumab and subsequent remission. Conclusion We present a novel mutation in the TNFRSF1A gene associated with amyloidosis. Canakinumab is an effective treatment for individuals with this new likely pathogenic variant. Alterations in the metabolome were most prominent in the pathways related to arginine biosynthesis, tryptophan metabolism, and metabolism of cysteine and methionine, and seemed to be unaffected by treatment with canakinumab. Further investigation is needed to determine the role of these metabolomic changes in the pathophysiology of TRAPS. [ABSTRACT FROM AUTHOR]

Purpose: The rise of female breast cancer has created a significant global public health issue that requires effective solutions. Disulfidptosis, a recently identified form of cell death characterized by an excessive accumulation of disulfides, has unique initiatory and regulatory mechanisms. The formation of disulfide bonds is a metabolic event typically associated with cysteines. This study aims to explore the potential of the affinity between cysteine metabolism and disulfidptosis in risk stratification for breast invasive carcinoma (BRCA). Methods: We used correlation analysis to decipher co-relation genes between cysteine metabolism and disulfidptosis (CMDCRGs). Both LASSO regression analysis and multivariate Cox regression analysis were employed to construct the prognostic signature. Additionally, we conducted investigations concerning subtype identification, functional enhancement, mutation landscape, immune infiltration, drug prioritization, and single-cell analysis. Results: We developed and validated a six-gene prognostic signature as an independent prognostic predictor for BRCA. The prognostic nomogram, based on risk score, demonstrated a favorable capability in predicting survival outcomes. We identified distinct gene mutations, functional enhancements, and immune infiltration patterns between the two risk groups. Four clusters of drugs were predicted as potentially effective for patients in the low-risk group. We identified seven cell clusters within the tumor microenvironment of breast cancer, and RPL27A was found to be widely expressed in this environment. Conclusion: Multidimensional analyses confirmed the clinical utility of the cysteine metabolism-disulfidptosis affinity-based signature in risk stratification and guiding personalized treatment for patients with BRCA. [ABSTRACT FROM AUTHOR]

Sarcopenia is an age-related, involuntary loss of skeletal muscle mass and strength. Alzheimer’s disease (AD) is the most common cause of dementia in elderly adults. To date, no effective cures for sarcopenia and AD are available. Physical and cognitive impairments are two major causes of disability in the elderly population, which severely decrease their quality of life and increase their economic burden. Clinically, sarcopenia is strongly associated with AD. However, the underlying factors for this association remain unknown. Mechanistic studies on muscle–brain crosstalk during cognitive impairment might shed light on new insights and novel therapeutic approaches for combating cognitive decline and AD. In this review, we summarize the latest studies emphasizing the association between sarcopenia and cognitive impairment. The underlying mechanisms involved in muscle–brain crosstalk and the potential implications of such crosstalk are discussed. Finally, future directions for drug development to improve age-related cognitive impairment and AD-related cognitive dysfunction are also explored. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the association between redox status in erythrocytes and skeletal muscle with dietary nutrient intake and markers of physical fitness and habitual physical activity (PA). Methods: Forty-five young physically active men were assessed for body composition, dietary nutrient intake, muscle strength, cardiorespiratory capacity and habitual PA. Blood and muscle samples were collected to estimate selected redox biomarkers. Partial correlation analysis was used to evaluate the independent relationship of each factor with redox biomarkers. Results: Dietary cysteine intake was positively correlated (p < 0.001) with both erythrocyte (r = 0.697) and muscle GSH (0.654, p < 0.001), erythrocyte reduced/oxidized glutathione ratio (GSH/GSSG) (r = 0.530, p = 0.001) and glutathione reductase (GR) activity (r = 0.352, p = 0.030) and inversely correlated with erythrocyte protein carbonyls (PC) levels (r = − 0.325; p = 0.046). Knee extensors eccentric peak torque was positively correlated with GR activity (r = 0.355; p = 0.031) while, one-repetition maximum in back squat exercise was positively correlated with erythrocyte GSH/GSSG ratio (r = 0.401; p = 0.014) and inversely correlated with erythrocyte GSSG and PC (r = − 0.441, p = 0.006; r = − 0.413, p = 0.011 respectively). Glutathione peroxidase (GPx) activity was positively correlated with step count (r = 0.520; p < 0.001), light (r = 0.406; p = 0.008), moderate (r = 0.417; p = 0.006), moderate-to-vigorous (r = 0.475; p = 0.001), vigorous (r = 0.352; p = 0.022) and very vigorous (r = 0.326; p = 0.035) PA. Muscle GSSG inversely correlated with light PA (r = − 0.353; p = 0.022). Conclusion: These results indicate that dietary cysteine intake may be a critical element for the regulation of glutathione metabolism and redox status in two different tissues pinpointing the independent significance of cysteine for optimal redox regulation. Musculoskeletal fitness and PA levels may be predictors of skeletal muscle, but not erythrocyte, antioxidant capacity. Trial registration: Registry: ClinicalTrials.gov, identifier: NCT03711838, date of registration: October 19, 2018. [ABSTRACT FROM AUTHOR]

Lung cancer is a lethal disease with no truly efficient therapeutic management despite the progresses, and metabolic profiling can be a way of stratifying patients who may benefit from new therapies. The present study is dedicated to profiling cysteine metabolic pathways in NSCLC cell lines and tumor samples. This was carried out by analyzing hydrogen sulfide (H2S) and ATP levels, examining mRNA and protein expression patterns of cysteine catabolic enzymes and transporters, and conducting metabolomics analysis using nuclear magnetic resonance (NMR) spectroscopy. Selenium–chrysin (SeChry) was tested as a therapeutic alternative with the aim of having an effect on cysteine catabolism and showed promising results. NSCLC cell lines presented different cysteine metabolic patterns, with A549 and H292 presenting a higher reliance on cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) to maintain H2S levels, while the PC-9 cell line presented an adaptive behavior based on the use of mercaptopyruvate sulfurtransferase (MST) and cysteine dioxygenase (CDO1), both contributing to the role of cysteine as a pyruvate source. The analyses of human lung tumor samples corroborated this variability in profiles, meaning that the expression of certain genes may be informative in defining prognosis and new targets. Heterogeneity points out individual profiles, and the identification of new targets among metabolic players is a step forward in cancer management toward personalized medicine.

Background. Baichanting (BCT),a traditional Chinese medicine prescription, is a combination of Acanthopanax senticosus, Paeonia lactiflora, and Uncaria three herbs, which has the effect of benefiting the kidney and calming the liver. The study was aimed at investigating the protective effect of BCT against Parkinson's disease using an integrated strategy of network pharmacology and brain metabolomics. Materials and Methods. By integrating network pharmacology with metabolomic research, the protective effect of BCT against PD was investigated using a transgenic mouse model for α-synuclein. The metabolite level and gene level components of BCT that might be anti-PD were separated out. Indicators of behavior and pharmacodynamics were employed to gauge the effectiveness of BCT on PD in the preliminary stages. Network pharmacology, which may be the target of BCT, screened the active substances and target genes. The use of metabolomics to identify potential biomarkers of PD, and then through network pharmacology and metabolic pathways to determine their regulatory enzymes and regulatory genes, improve the pathway mechanism of the disease, has important guiding significance for the in-depth study of the pathogenesis of PD. Results. 101 putative target genes were identified by the network pharmacology analysis in relation to the treatment of PD with BCT. According to the functional enrichment analysis, the proposed mechanism was primarily related to the transport of neurotransmitters, the metabolism of arachidonic acid, dopamine, and alpha-amino acids, as well as the transport of dopamine and the negative regulation of amino acid transport. 25 distinct endogenous metabolites were shown to be potential biomarkers for the BCT for treating PD based on metabolomics. These metabolites were mostly implicated in the important methionine and cysteine, tyrosine, histidine, and arginine and proline metabolic pathways. These results somewhat agreed with those of the network pharmacology analysis. Conclusions. In conclusion, this study showed that BCT could delay the occurrence and development of PD by improving the brain metabolic disorder of α-Syn mice, which revealed the mechanism of BCT through multitarget and multipathway treatment, and provided a new explanation for the mechanism of anti-PD action. Our research, on the other hand, demonstrated that the network pharmacology-integrated metabolomics approach was a potent tool for discovering the active ingredients and mechanisms underlying the pharmacological effects of traditional Chinese medicine. [ABSTRACT FROM AUTHOR]

Cysteinyl leukotrienes (CysLTs) are inflammatory lipid mediators that play a central role in the pathophysiology of several inflammatory diseases. Recently, there has been an increased interest in determining how these lipid mediators orchestrate tumour development and metastasis through promoting a pro-tumour micro-environment. Up-regulation of CysLTs receptors and CysLTs production is found in a number of cancers and has been associated with increased tumorigenesis. Understanding the molecular mechanisms underlying the role of CysLTs and their receptors in cancer progression will help investigate the potential of targeting CysLTs signalling for anti-cancer therapy. This review gives an overview of the biological effects of CysLTs and their receptors, along with current knowledge of their regulation and expression. It also provides a recent update on the molecular mechanisms that have been postulated to explain their role in tumorigenesis and on the potential of anti-CysLTs in the treatment of cancer. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of cystathionine β-synthase (CBS) on the proliferation of lung adenocarcinoma A549 cells through the AKT/cyclin D1 pathway and its molecular mechanism. Methods: Expression of CBS and AKT/cyclinD1-related proteins in lung adenocarcinoma tissues was analyzed by cBioPortal database. The CBS expression in collected lung adenocarcinoma tissues from Chinese patients was verified by immunofluorescence method. WB assay was performed to detect the expression of cysteine metabolism and AKT/cyclin D1 pathway-related proteins in A549 cells and their transplanted tumors, and CBS DNA methylation sequencing was performed to detect the effect of its methylation on CBS mRNA expression in lung cancer cells. The pCW57.1-myrAKT plasmid was co-transfected with RNA interference control plasmid pGIPZ-CBS-nc-shRNA, interference plasmid pGIPZ-CBS-shNRA1 and pGIPZ-CBS-shNRA2, respectively, into A549 cells, which were further sub-divided into DOX+ and DOX- groups. The colony formation ability of A549 cells in each group after transfection was examined by cell colony formation assay. The effect of overexpression of CBS on the growth of transplanted tumors was examined by CBSwtA549 cell- and CBSI278TA549 celltransplanted tumor assay, and AzMC fluorescence staining and immunohistochemistry were used to detect H2S levels and Ki-67 positivity in transplanted tumor tissues, respectively. Results: Both database analysis and tissue specimens showed that CBS was lowly expressed in lung adenocarcinoma tissues compared with para-cancerous tissues (all P<0.01); CBS protein was lowly expressed in A549, SKMES1 and NCIH460 cells compared with SV-40 cells (all P<0.01), while p-AKT and cyclin D1 protein levels were highly expressed (all P<0.01). Overexpression of AKT in A549 cells significantly promoted the formation of cell colonies (P<0.01), and knockdown of CBS on this basis further promoted the formation of cell colonies (all P<0.01). Transplantation tumor experiments showed that CBS, RB and P21 protein expression was elevated, H2S level was increased, tumor volume was decreased and Ki-67 positivity was reduced in the DOX+ CBSWT group compared with those in the DOX- CBSWT group (all P<0.01); CBS expression was elevated in the DOX+ CBSI278T group compared with the DOX-CBSI278T group (P<0.01), but the changes in H2S level and transplantation tumor volume were not significant. Conclusions: CBS is lowly expressed in lung adenocarcinoma tissues and A549 cells, while the AKT/cyclinD1 pathway is activated. Overexpression or knockdown of CBS can inhibit or promote the growth of A549 cells and their transplanted tumors, and CBS and AKT/cyclin D1 pathway-related proteins may be the potential targets and markers for lung adenocarcinoma. [ABSTRACT FROM AUTHOR]

Objective: Obesity contributes to the dysfunction of salivary gland. To explore the specific underlying mechanism for obesity‐induced hyposalivation, a model for high‐fat diet‐induced obese (DIO) mice were constructed to analyze long non‐coding RNAs (lncRNAs) and messenger RNAs (mRNAs) expression profiles. Methods: The DIO group and control group were fed a diet containing 60 kcal% fat and a normal chow diet for 16 weeks respectively. Microarray analyses were performed to detect the expression profiles of lncRNA and mRNA in submandibular gland tissues from control group mice and DIO mice. Gene ontology, kyoto encyclopedia of genes and genomes, protein–protein interaction, coding‐non‐coding gene co‐expression, transcription factors and competing endogenous RNA analyses were performed to examine the function of differentially expressed genes. Results: Microarray analyses identified that 624 lncRNAs, along with 297 mRNAs were differentially expressed. Bioinformatic analyses revealed that "complement and coagulation cascades," "glutathione metabolism," "cysteine and methionine metabolism," and "estrogen signaling pathway" were significantly associated with candidate lncRNAs. Transcription factors analysis on candidate lncRNAs revealed several genes such as tribbles pseudokinase 3 may play regulatory roles. Conclusions: Our results revealed the expression profiles of lncRNAs and mRNAs and provided new insights into the mechanism of obesity‐induced hyposalivation using bioinformatic analyses. [ABSTRACT FROM AUTHOR]

Metabolic dysfunction-associated steatotic liver disease (MASLD) remains a rapidly growing global health burden. Here, we report that the nonessential amino acid (NEAA) transporter SLC7A11 plays a key role in MASLD. In patients with MASLD, we found high expression levels of SLC7A11 that were correlated directly with clinical grade. Using both loss-of-function and gain-of-function genetic models, we found that Slc7a11 deficiency accelerated MASLD progression via classic cystine/cysteine deficiency-induced ferroptosis, while serine deficiency and a resulting impairment in de novo cysteine production were attributed to ferroptosis-induced MASLD progression in mice overexpressing hepatic Slc7a11. Consistent with these findings, we found that both serine supplementation and blocking ferroptosis significantly alleviated MASLD, and the serum serine/glutamate ratio was significantly lower in these preclinical disease models, suggesting that it might serve as a prognostic biomarker for MASLD in patients. These findings indicate that defects in NEAA metabolism are involved in the progression of MASLD and that serine deficiency-triggered ferroptosis may provide a therapeutic target for its treatment., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

By identifying distance constraints, chemical cross-linking coupled with mass spectrometry (CX-MS) can be a powerful complementary technique to other structural methods by interrogating macromolecular protein complexes under native-like conditions. In this study, we developed a CX-MS approach to identify the sites of chemical cross-linking from a single targeted location within the human α1 glycine receptor (α1 GlyR) in its apo state. The human α1 GlyR belongs to the family of pentameric ligand-gated ion channel receptors that function in fast neurotransmission. A single chemically reactive cysteine was reintroduced into a Cys null α1 GlyR construct at position 41 within the extracellular domain of human α1 homomeric GlyR overexpressed in a baculoviral system. After purification and reconstitution into vesicles, methanethiosulfonate-benzophenone-alkyne, a heterotrifunctional cross-linker, was site specifically attached to Cys41 via disulfide bond formation. The resting receptor was then subjected to UV photocross-linking. Afterward, monomeric and oligomeric α1 GlyR bands from SDS-PAGE gels were trypsinized and analyzed by tandem MS in bottom-up studies. Dozens of intrasubunit and intersubunit sites of α1 GlyR cross-linking were differentiated and identified from single gel bands of purified protein, showing the utility of this experimental approach to identify a diverse array of distance constraints of the α1 GlyR in its resting state. These studies highlight CX-MS as an experimental approach to identify chemical cross-links within full-length integral membrane protein assemblies in a native-like lipid environment., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

The sugar-binding receptor mincle stimulates macrophages when it encounters surface glycans on pathogens, such as trehalose dimycolate glycolipid in the outer membrane of mycobacteria. Binding of oligosaccharide ligands to the extracellular C-type carbohydrate-recognition domain (CRD) in mincle initiates intracellular signaling through the common Fc receptor γ (FcRγ) adapter molecule associated with mincle. One potential mechanism for initiation of signaling involves clustering of receptors, so it is important to understand the oligomeric state of mincle. Affinity purification of mincle from transfected mammalian cells has been used to show that mincle exists as a pre-formed, disulfide-linked dimer. Deletion of cysteine residues and chemical crosslinking further demonstrate that the dimers of mincle are stabilized by a disulfide bond between cysteine residues in the neck sequence that links the CRD to the membrane. In contrast, cysteine residues in the transmembrane region of mincle are not required for dimer formation or association with FcRγ. A protocol has been developed for efficient production of a disulfide-linked extracellular domain fragment of mincle in a bacterial expression system by appending synthetic dimerization domains to guide dimer formation in the absence of the membrane anchor., (© The Author(s) 2024. Published by Oxford University Press.)

α-Cyanostilbene represents one of the easily functionalized aggregation-induced emission (AIE) scaffolds. It has been widely adopted for the construction of fluorescent materials for broad applications. Here, we further expanded the utilization of α-cyanostilbene derivatives for the detection of hypoxia or proteostasis imbalance in live cells. Four different amine containing donors were introduced to construct α-cyanostilbene derivatives (R-ASC) with donor-acceptor scaffolds. Equipped with the cysteine (Cys) reactive group, maleimide (MI), R-ASC-MI shows fluorescence turn-on property upon binding with unfolded proteins in vitro and in live cells under proteostatic stress. By virtue of R-ASC-MI, the level of unfolded protein loads in cells can be quantified by flow cytometry, or visualized under microscope. Furthermore, we also characterized the performance of R-ASC-NO 2 , synthetic precursors of R-ASC-MI, in cellular hypoxia. R-ASC-NO 2 revealed upregulated activities of nitroreductase, as well as increased hydrophobicity in live cells, under either chemical (NaN 3 ) induced or atmospheric (1 % O 2 ) hypoxia. Together, the advantages of easy modification and high signal-to-noise ratio of new α-cyanostilbene derivatives reported in this work highlight the great potential of α-cyanostilbene in constructing functional biosensors and many other domains., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

Iron-based nanozymes, recognized for their biocompatibility and peroxidase-like activities, hold promise as catalysts in tumor therapy. However, their concurrent catalase-like activity undermines therapeutic efficacy by converting hydrogen peroxide in tumor tissues into oxygen, thus diminishing hydroxyl radical production. Addressing this challenge, this study introduces the hemin-cysteine-Fe (HCFe) nanozyme, which exhibits exclusive peroxidase-like activity. Constructed through a supramolecular assembly approach involving Fmoc-L-cysteine, heme, and Fe²⁺ coordination, HCFe distinctly incorporates heme and [Fe-S] within its active center. Sulfur coordination to the central Fe atom of Hemin is crucial in modulating the catalytic preference of the HCFe nanozyme towards peroxidase-like activity. This unique mechanism distinguishes HCFe from other bifunctional iron-based nanozymes, enhancing its catalytic selectivity even beyond that of natural peroxidases. This selective activity allows HCFe to significantly elevate ROS production and exert cytotoxic effects, especially against cisplatin-resistant esophageal squamous cell carcinoma (ESCC) cells and their xenografts in female mice when combined with cisplatin. These findings underscore HCFe's potential as a crucial component in multimodal cancer therapy, notably in augmenting chemotherapy efficacy., Competing Interests: Competing interests: The authors have declared that no competing interest exists., (© 2024. The Author(s).)

Hydrogen sulfide (H2S) played a pivotal role in the early evolution of life on Earth before the predominance of atmospheric oxygen. The legacy of a persistent role for H2S in life's processes recently emerged through its discovery in modern biochemistry as an endogenous cellular signalling modulator involved in numerous biological processes. One major mechanism through which H2S signals is protein cysteine persulfidation, an oxidative post-translational modification. In recent years, chemoproteomic technologies have been developed to allow the global scanning of protein persulfidation targets in mammalian cells and tissues, providing a powerful tool to elucidate the broader impact of altered H2S in organismal physiological health and human disease states. While hundreds of proteins were confirmed to be persulfidated by global persulfidome methodologies, the targeting of specific proteins of interest and the investigation of further mechanistic studies are still underdeveloped due to a lack of stringent specificity of the methods and the inherent instability of persulfides. This review provides an overview of the processes of endogenous H2S production, oxidation, and signalling and highlights the application and limitations of current persulfidation labelling approaches for investigation of this important evolutionarily conserved biological switch for protein function., (© 2024 The Author(s).)

In proteomics, postproline cleaving enzymes (PPCEs), such as Aspergillus niger prolyl endopeptidase ( An PEP) and neprosin, complement proteolytic tools because proline is a stop site for many proteases. But while aiming at using An PEP in online proteolysis, we found that this enzyme also displayed specificity to reduced cysteine. By LC-MS/MS, we systematically analyzed An PEP sources and conditions that could affect this cleavage preference. Postcysteine cleavage was blocked by cysteine modifications, including disulfide bond formation, oxidation, and alkylation. The last modification explains why this activity has remained undetected so far. In the same experimental paradigm, neprosin mimicked this cleavage specificity. Based on these findings, PPCEs cleavage preferences should be redefined from post-Pro/Ala to post-Pro/Ala/Cys. Moreover, this evidence demands reconsidering PPCEs applications, whether cleaving Cys-rich proteins or assessing Cys status in proteins, and calls for revisiting the proposed enzymatic mechanism of these proteases.

Intensive agricultural practices impact the health and nutrition of pollinators like honey bees ( Apis mellifera ). Rapeseed ( Brassica napus L.) is widely cultivated, providing diverse nutrients and phytochemicals, including S -methyl-L-cysteine sulfoxide (SMCSO). While the nutritional impact of rapeseed on bees is known, SMCSO's effects remain unexplored. We examined SMCSO and its related metabolites-3-methylthiolactic acid sulfoxide and N -acetyl -S -methyl-L-cysteine sulfoxide-analysing their seasonal fluctuations, colony variations and distribution in body parts. Our findings showed that these compounds in bee gut vary among colonies, possibly due to the dietary preferences, and are highly concentrated in bodies during the summer. They are distributed differently within bee bodies, with higher concentrations in the abdomens of foragers compared with nurses. Administration of SMCSO in a laboratory setting showed no immediate toxic effects but significantly boosted bees' antioxidant capacity. Long-term administration decreased bee body weight, particularly in the thorax and head, and altered amino acid metabolism. SMCSO is found in the nectar and pollen of rapeseed flowers and highly accumulates in rapeseed honey compared with other types of honey. This study reveals the dual impact of SMCSO on bee health, providing a basis for further ecological and physiological research to enhance bee health and colony sustainability.

The experimental challenges posed by integral membrane proteins hinder molecular understanding of transmembrane signaling mechanisms. Here, we exploited protein crosslinking assays in living cells to follow conformational and dynamic stimulus signals in Tsr, the Escherichia coli serine chemoreceptor. Tsr mediates serine chemotaxis by integrating transmembrane serine-binding inputs with adaptational modifications of a methylation helix bundle to regulate a signaling kinase at the cytoplasmic tip of the receptor molecule. We created cysteine replacements at Tsr residues adjacent to hydrophobic packing faces of the bundle helices and crosslinked them with a cell-permeable, bifunctional thiol-reagent. We identified an extensively crosslinked dynamic junction midway through the methylation helix bundle that seemed uniquely poised to respond to serine signals. We explored its role in mediating signaling shifts between different packing arrangements of the bundle helices by measuring crosslinking in receptor molecules with apposed pairs of cysteine reporters in each subunit and assessing their signaling behaviors with an in vivo kinase assay. In the absence of serine, the bundle helices evinced compact kinase-ON packing arrangements; in the presence of serine, the dynamic junction destabilized adjacent bundle segments and shifted the bundle to an expanded, less stable kinase-OFF helix-packing arrangement. AlphaFold models of kinase-active Tsr showed a prominent bulge and kink at the dynamic junction that might antagonize stable structure at the receptor tip. Serine stimuli might inhibit kinase activity by shifting the bundle to a less stably-packed conformation that relaxes structural strain at the receptor tip, thereby allowing it to stabilize and freeze kinase activity., (© 2024 The Author(s). Protein Science published by Wiley Periodicals LLC on behalf of The Protein Society.)

In this study, we investigated formation of the complex between glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and actin and the possibility of nitrosyl group transfer between GAPDH and actin. A complex of GAPDH with beta-actin was isolated from lysates of HEK293T cells using immunoprecipitation with antibodies against GAPDH or against beta-actin. The treatment of the cells with H 2 O 2 or NO donor did not affect the formation of the complex. Investigation of the interaction between purified GAPDH and muscle alpha-actin showed that GAPDH interacts better with globular (G-) actin than with fibrillary actin, and oxidation/reduction of GAPDH does not affect this interaction. S-nitrosylated GAPDH (GAPDH-SNO) was partially reactivated in the presence of G-actin, which was accompanied by denitrosylation of GAPDH and sulfenation of G-actin. The sulfenated cysteine residue in G-actin was identified by MALDI-TOF MS analysis as C-terminal Cys374. Based on the properties of nitrosothiols, we assume that the cysteine-sulfenic acid in actin is a product of spontaneous hydrolysis of S-nitrosylated cysteine residue. The obtained results suggest that Cys374 in actin is S-nitrosylated during the incubation with GAPDH-SNO (transnitrosylation reaction). The transfer of the NO-group from GAPDH-SNO to the C-terminal Cys374 of actin suggests that upon interaction with GAPDH, the C-terminus of actin is located in the active center of GAPDH in the proximity to the catalytic Cys152. It is possible that the ability of GAPDH-SNO to nitrosylate actin contributes to the redox regulation of actin-controlled signaling pathways., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Autographa californica nucleopolyhedrovirus orf89 (vp39) encodes the major capsid protein VP39. Multiple alignments of protein sequences showed that VP39 has 8 conserved cysteine (Cys) residues. Cysteine residues play an important role in proper function of a protein. To determine the importance of these conserved cysteine residues for virus proliferation, a series of recombinant viruses harboring VP39-Cys mutants were constructed. Viral growth curves and transmission electron microscopy showed that mutation of Cys29, Cys132, Cys169, Cys229, or Cys232 of VP39 to alanine did not affect budded virion production; however, the mutation of Cys18, Cys36, or Cys49 to alanine resulted in interruption of capsid assembly. Co-immunoprecipitation assays showed that mutations of these 8 cysteines individually or simultaneously had no effect on self-association of VP39. Immunofluorescence analysis by confocal microscopy revealed that the subcellular localization of VP39 with mutations in Cys18, Cys36 or Cys49 was exclusively distributed in the cytoplasm of a cell regardless of virus infection or not, while the wild-type VP39 or the VP39 carrying mutations in Cys29, Cys132, Cys169, Cys229, or Cys232 was distributed throughout the cytoplasm and the nucleus. Our results demonstrated that Cys18, Cys36, and Cys49 are essential for the proper localization of VP39, which is a prerequisite for successful nucleocapsid assembly of the virus., Competing Interests: Declarations Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: D-amino acids are being recognized as important molecules in mammals with function. This is a first identification of endogenous D-cysteine in mammalian pancreas., Methods: Using a novel stereospecific bioluminescent assay, chiral chromatography, enzyme kinetics and a transgenic mouse model we identify endogenous D-cysteine. We elucidate its function in two mice models of type 1 diabetes (STZ and NOD), and in tests of Glucose Stimulated Insulin Secretion in isolated mouse and human islets and INS-1 832/13 cell line., Results and Discussion: D-cysteine is synthesized by serine racemase (SR) and SR -/- mice produce 6-10 fold higher levels of insulin in the pancreas and plasma including higher glycogen and ketone bodies in the liver. The excess insulin is stored as amyloid in secretory vesicles and exosomes. In glucose stimulated insulin secretion in mouse and human islets, equimolar amount of D-cysteine showed higher inhibition of insulin secretion compared to D-serine, another closely related stereoisomer synthesized by SR. In mouse models of diabetes (Streptozotocin (STZ) and Non Obese Diabetes (NOD) and human pancreas, the diabetic state showed increased expression of D-cysteine compared to D-serine followed by increased expression of SR. SR -/- mice show decreased cAMP in the pancreas, lower DNA methyltransferase enzymatic and promoter activities followed by reduced phosphorylation of CREB (S133), resulting in decreased methylation of the Ins1 promoter. D-cysteine is efficiently metabolized by D-amino acid oxidase and transported by ASCT2 and Asc1. Dietary supplementation with methyl donors restored the high insulin levels and low DNMT enzymatic activity in SR -/- mice., Conclusions: Our data show that endogenous D-cysteine in the mammalian pancreas is a regulator of insulin secretion., Competing Interests: Declaration of competing interest Authors declare no conflict of interest., (Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Porphyromonas gingivalis is a keystone pathogen in periodontitis, and Streptococcus sanguinis is an abundant oral commensal bacterium associated with periodontal health. However, the interaction between P. gingivalis and S. sanguinis remains obscure. Here, we established a strategy for high-throughput measurement of the cell number of P. gingivalis in the coculture with S. sanguinis by detecting the concentration of hydrogen sulfate. The interaction between P. gingivalis and over 2000 S. sanguinis single-gene mutants was characterized using this strategy, and several interaction-associated genes in S. sanguinis were determined by detecting more P. gingivalis cells in the coculture with matched S. sanguinis mutants. Three S. sanguinis interaction-associated genes were predicted to be responsible for cysteine metabolism, and the supplementation of exogenous L-cysteine promoted the cell number of P. gingivalis in the coculture with S. sanguinis. Thus, exogenous L-cysteine and the compromised cysteine metabolism in S. sanguinis enhanced the growth of P. gingivalis in the existence of S. sanguinis. Additionally, the interaction between P. gingivalis and other Streptococcus spp. was examined, and S. pneumoniae was the only streptococci that had no inhibition on the cell number of P. gingivalis. In total, this study established a new strategy for high-throughput screening of the interaction between Streptococcus and P. gingivalis and discovered a set of genes in S. sanguinis that impacted the interaction. The influence of exogenous L-cysteine on the interaction between P. gingivalis and S. sanguinis in the oral cavity needs further investigation., (© 2024 The Author(s). Molecular Oral Microbiology published by John Wiley & Sons Ltd.)

Parkinson's disease (PD), the most prevalent type of parkinsonism, is a progressive neurodegenerative condition marked by several non-motor and motor symptoms. PD is thought to have a complex aetiology that includes a combination of age, genetic predisposition, and environmental factors. Increased expression of α-synuclein (α-Syn) protein is central to the evolvement of neuropathology in this devastating disorder, but the potential of ribose-cysteine and levodopa in abating pathophysiologic changes in PD model is unknown. Crosses were set up between flies conditionally expressing a pathological variant of human α-Syn (UAS-α-Syn) and those expressing GAL4 in neurons (elav-GAL4) to generate offspring referred to as PD flies. Flies were randomly assigned to five groups ( n  = 40) from the total population of flies, with each group having five replicates. Groups of PD flies were treated with either 500 mg/kg ribose-cysteine diet, 250 mg/kg levodopa diet, or a combination of the two compounds for 21 days, whereas the control group (w 1118 ) and the PD group were exposed to a diet without ribose-cysteine or levodopa. In addition to various biochemical and neurochemical assays, longevity, larval motility, and gravitaxis assays were carried out. Locomotive capability, lifespan, fecundity, antioxidant state, and neurotransmitter systems were all significantly ( p  < 0.05) compromised by overexpression of α-Syn. However, flies treated both ribose cysteine and levodopa showed an overall marked improvement in motor functions, lifespan, fecundity, antioxidant status, and neurotransmitter system functions. In conclusion, ribose-cysteine and levodopa, both singly and in combination, potentiated a therapeutic effect on alpha-synuclein transgenic Drosophila melanogaster models of Parkinsonism.

C-terminal α-amidated peptides are attractive therapeutic targets, but preparative methods to access amidated pharmaceuticals are limited both on lab and manufacturing-scale. Here we report a straightforward and scalable approach to the C-terminal α-amidation of peptides and proteins from cysteine-extended polypeptide precursors. This amidation protocol consists of three highly efficient steps: 1) selective cysteine thiol substitution with a photolabel, 2) photoinduced decarboxylative elimination and 3) enamide cleavage by simple acidolysis or inverse electron demand Diels-Alder reaction. We provide a blueprint for applying this protocol to the semi-recombinant production of therapeutically relevant targets where gram scale C-terminal α-amidation is achieved in a photoflow reactor on a recombinantly prepared peptide YY analogue and a GLP-1/amylin co-agonist precursor peptide. Robust performance of this reaction cascade in flow highlights the potential of this chemistry to enable amidated drug leads to enter development that would not be viable on commercial scale using existing technology., Competing Interests: Competing interests: All authors except S. C. W. are employees and minor shareholders of Novo Nordisk A/S. D.H., F.W., W.F.J.H., S.C.W., B.M.W., N.C., A.R.M., M.R.H are co-inventors of a patent application (WO23105074A1) describing photochemically enabled amidations., (© 2024. The Author(s).)

Formation and breakage of disulfide bridges strongly impacts folding and activity of proteins. Thioredoxin 1 (TrxA) is a small, conserved enzyme that reduces disulfide bonds in the bacterial cytosol. In this study, we provide an example of the emergence of a chaperone role for TrxA, which is independent of redox catalysis. We show that the activity of the secreted bacterial ADP-ribosyltransferase (ART) toxin TreX, which does not contain any cysteines, is dependent on TrxA. TreX binds to the reduced form of TrxA via its carboxy-terminal extension to form a soluble and active complex. Structural studies revealed that TreX-like toxins are homologous to Scabin-like ART toxins which possess cysteine residues and form disulfide bridges at the position that superimposes the TrxA binding site in TreX. Our study therefore suggests that thioredoxin 1 evolved alternative functions by maintaining the interaction with cysteine-free substrates., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

The effects of sequential cold extrusion and cysteine (Cys) treatment on the rheological characteristics and in vitro digestibility of whey protein isolate (WPI) were researched in this work. Cold extrusion and Cys treatment increased the apparent viscosity, shear stress, Péclet number, and viscoelasticity of WPI. Furthermore, the emulsifying activity index enhanced in the order of WPI, Cys-treated WPI (Cys-WPI), cold-extruded WPI (CWPI), and extrusion-Cys treated WPI (Cys-CWPI). The emulsion stability index of Cys-CWPI was increased by 29.69% higher than that of WPI. Besides, the α-glucosidase inhibitory rate and xanthine oxidase inhibitory activity in the digests of Cys-CWPI were markedly increased compared with digests of WPI. The synergism of cold extrusion and Cys provides an effective approach for the application of whey protein-based thickeners and emulsifiers; meanwhile, its digestive products may assist in the development of hypoglycemic and uric acid-lowering foods.

Interleukin (IL)-1 family cytokines are essential for host defense at epithelial barriers. The IL-1 family member IL-33 was recently linked to stress granules (SGs). Formation of SGs and other biomolecular condensates is promoted by proteins containing low-complexity regions (LCRs). Computational analysis predicts LCRs in six of the 11 IL-1 family members. Among these, IL-38 contains a long LCR including two amyloid cores. IL-38 localizes to intracellular granules in keratinocytes under oxidative stress (OS) and forms OS-induced amyloid aggregates in cells and in vitro. Interestingly, soluble and aggregated IL-38 are released from keratinocytes in an exosome-enriched extracellular vesicle fraction. Disulfide-bond mapping, in silico modeling, and mutational analysis suggest that oxidation-sensitive cysteines act as redox switches to alter IL-38 conformation and promote its aggregation. Finally, the presence of IL-38 granules in human epidermis facing environmental OS suggests that oxidation-induced amyloidogenesis, as an intrinsic property of IL-38, supports barrier function., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

The challenge of understanding the interaction between trace elements and microbial life is critical for assessing environmental and ecological impacts. Nevertheless, cysteine (Cys), a low molecular weight thiol substance prevalent in the ecosystem, is able to influence the fate of certain trace elements, which increases the complexity of the interaction between trace elements and microorganisms. Therefore, we chose Cys, selenite and the model methanogenic archaeon Methanosarcina acetivorans C2A as research targets, and comprehensively explored the intricate role of Cys in modulating the biological effects of selenite on M. acetivorans C2A in terms of population growth, methane production and oxidative stress. Our results demonstrate that Cys significantly exacerbates the inhibitory effects of selenite on growth and methane production in M. acetivorans C2A. This increased toxicity is linked to heightened membrane permeability and oxidative stress, with a marked upregulation in reactive oxygen species and changes in NADPH levels. Transcriptomic analysis reveals alterations in genes associated with transmembrane transport and methanogenesis. Intriguingly, we also observed a potential interaction between selenite and phosphate transmembrane transporters, suggesting a novel pathway for selenite entry into cells. These findings highlight the complex interplay between trace elements and microbial processes, with significant implications for understanding environmental risks and developing remediation strategies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Ferroptosis, a regulated form of cell death dependent on reactive oxygen species (ROS), is characterized by iron accumulation and lethal lipid peroxidation. Mitochondria serve as the primary source of ROS and thus play a crucial role in ferroptosis initiation and execution. This study highlights the role of mitochondrial ROS and the significance of voltage-dependent anion channel 1 (VDAC1) oligomerization in ferroptosis induced by cysteine deprivation or ferroptosis-inducer RSL3. Our results demonstrate that the mitochondria-targeted antioxidants MitoQ and MitoT effectively block ferroptosis induction and that dysfunction of complex III of the mitochondrial electron transport chain contributes to ferroptosis induction. Pharmacological inhibitors that target VDAC1 oligomerization have emerged as potent suppressors of ferroptosis that reduce mitochondrial ROS production. These findings underscore the critical involvement of mitochondrial ROS production via complex III of the electron transport chain and the essential role of VDAC1 oligomerization in ferroptosis induced by cysteine deprivation or RSL3. This study deepens our understanding of the intricate molecular networks governing ferroptosis and provides insights into the development of novel therapeutic strategies targeting dysregulated cell death pathways., (© 2024. The Author(s).)

Enhancer of zeste homolog 2 (EZH2), a key protein implicated in various cancers including hepatocellular carcinoma (HCC), is recognized for its association with epigenetic dysregulation and pathogenesis. Despite clinical explorations into EZH2-targeting therapies, the mechanisms underlying its role in gene suppression in HCC have remained largely unexplored. Here, we integrate epigenomic and transcriptomic analyses to uncover the transcriptional landscape modulated by selective EZH2 inhibition in HCC. By reanalyzing transcriptomic data of HCC patients, we demonstrate that EZH2 overexpression correlates with poor patient survival. Treatment with the EZH2 inhibitor tazemetostat restored expression of genes involved in cysteine-methionine metabolism and lipid homeostasis, while suppressing angiogenesis and oxidative stress-related genes. Mechanistically, we demonstrate EZH2-mediated H3K27me3 enrichment at cis-regulatory elements of transsulfuration pathway genes, which is reversed upon inhibition, leading to increased chromatin accessibility. Among 16 EZH2-targeted candidate genes, BHMT and CDO1 were notably correlated with poor HCC prognosis. Tazemetostat treatment of HCC cells increased BHMT and CDO1 expression while reducing levels of ferroptosis markers FSP1, NFS1, and SLC7A11. Functionally, EZH2 inhibition dose-dependently reduced cell viability and increased lipid peroxidation in HCC cells. Our findings reveal a novel epigenetic mechanism controlling lipid peroxidation and ferroptosis susceptibility in HCC, providing a rationale for exploring EZH2-targeted therapies in this malignancy., (© 2024. The Author(s).)

The major histocompatibility complex class I antigen presentation pathways play pivotal roles in orchestrating immune responses. Recent studies have begun to explore the therapeutic potential of cysteines within the immunopeptidome, such as the use of covalent ligands to generate haptenated peptide neoepitopes for immunotherapy. In this work, we report a platform for mapping reactive cysteines on MHC-I-bound peptide antigens. We develop cell-impermeable sulfonated maleimide probes capable of capturing reactive cysteines on these antigens. Using these probes in chemoproteomic experiments, we discover that cysteines on MHC-I-bound antigens exhibit various degrees of reactivity. Moreover, interferon-gamma stimulation enhances the reactivity of cysteines at position 8 of 9-mer MHC-I-bound antigens. Finally, we demonstrate that targeting reactive cysteines on MHC-I-bound antigens with a maleimide-conjugated Fc-binding cyclic peptide contributes to the induction of antibody-dependent cellular phagocytosis., (© 2024. The Author(s).)

The enzymatically regioselective catalyzed incorporation of cysteine sulfoxide into histidine generates physiologically important antioxidants such as ergothioneine and ovothiol. In this issue of Structure, Ireland et al. 1 report the crystal structure of EgtB-IV, which provides insights into the convergent evolution of sulfoxide synthase., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Pioneer transcription factors (TFs) bind to and open closed chromatin, facilitating engagement by other regulatory factors involved in gene activation or repression. Chemical probes are lacking for pioneer TFs, which has hindered their mechanistic investigation in cells. Here, we report the chemical proteomic discovery of electrophilic compounds that stereoselectively and site-specifically bind the pioneer TF forkhead box protein A1 (FOXA1) at a cysteine (C258) within the forkhead DNA-binding domain. We show that these covalent ligands react with FOXA1 in a DNA-dependent manner and rapidly remodel its pioneer activity in prostate cancer cells reflected in redistribution of FOXA1 binding across the genome and directionally correlated changes in chromatin accessibility. Motif analysis supports a mechanism where the ligands relax the canonical DNA-binding preference of FOXA1 by strengthening interactions with suboptimal sequences in predicted proximity to C258. Our findings reveal a striking plasticity underpinning the pioneering function of FOXA1 that can be controlled by small molecules., Competing Interests: Declaration of interests B.F.C. is a scientific advisor to Vividion Therapeutics. M.A.E. holds equity in Nexo Therapeutics and serves on their scientific advisory board., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In yeast, control of sulfur amino acid metabolism relies upon Met4, a transcription factor that activates the expression of a network of enzymes responsible for the biosynthesis of cysteine and methionine. In times of sulfur abundance, the activity of Met4 is repressed via ubiquitination by the SCFMet30 E3 ubiquitin ligase, but the mechanism by which the F-box protein Met30 senses sulfur status to tune its E3 ligase activity remains unresolved. Herein, we show that Met30 responds to flux through the trans-sulfuration pathway to regulate the MET gene transcriptional program. In particular, Met30 is responsive to the biological gas hydrogen sulfide, which is sufficient to induce ubiquitination of Met4 in vivo. Additionally, we identify important cysteine residues in Met30's WD-40 repeat region that sense the availability of sulfur in the cell. Our findings reveal how SCFMet30 dynamically senses the flow of sulfur metabolites through the trans-sulfuration pathway to regulate the synthesis of these special amino acids., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America.)

Heavy metals, including Hg 2+ , Cr 6+ and Cd 2+ , have always been a major issue in environmental pollution, leading to abnormal changes in the levels of biologically active molecules including Cys in plants, seriously affecting all aspects of the growth and development of plants. This makes it essential to develop a simple and practical method to study the potential impact of heavy metals on plants. In this paper, our research group has developed near-infrared fluorescent probe WRM-S, which has the advantages of fast response, sensitivity to Cys, and successfully applying it to cells and zebrafish. Moreover, it combined the close relationship between heavy metal stress on plants and Cys, using Cys as the detection target, monitoring the internal environment changes of two plants under Hg 2+ , Cr 6+ , and Cd 2+ stress in the environment, and then conducting 3D imaging. The results indicated that the probe has strong penetration ability in plant tissues, and revealed abnormal changes in plant Cys levels caused by heavy metal stress-induced cellular oxidative stress or cytotoxicity. Thus, the in-situ imaging detection of this probe provides a direction for the physiological dynamics research of plant environmental stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Endogenous H 2 S has been proposed to be a universal defense mechanism against different antibiotics. Here, we studied the role of H 2 S transiently generated during ciprofloxacin (CF) treatment in M9 minimal medium with sulfate or produced by E. coli when fed with cystine. The cysM and mstA mutants did not produce H 2 S, while gshA generated more H 2 S in response to ciprofloxacin in cystine-free media. All mutants showed a reduced ability to maintain cysteine homeostasis under these conditions. We found no relationship between H 2 S generation, cysteine concentration and sensitivity to ciprofloxacin. Excess cysteine, which occurred during E. coli growth in cystine-fed media, triggered continuous H 2 S production, accelerated glutathione synthesis and cysteine export. This was accompanied by a twofold increase in ciprofloxacin tolerance in all strains except gshA, whose sensitivity increased 5-8-fold at high CF doses, indicating the importance of GSH in restoring the intracellular redox situation during growth in cystine-fed media., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

ADAM17 sheds EGFR/erbB ligands and triggers oncogenic pathways that lead to the progression of solid tumors. We targeted the ADAM17 disintegrin and cysteine rich domain region (D+C) to generate a panel of single-chain antibody fragments (scFvs) that selectively bind to the D or C domains of ADAM17, but not of ADAM10 or ADAM19. From the panel, we selected one scFv, referred to as C12, based on its high binding affinity towards the target, and re-formatted it to a full IgG for further studies. High-resolution cryo-electron microscopy studies documented that the mAb binds to the ADAM17 C-domain that in ADAM proteases, notably ADAM10 and ADAM17, is known to impart substrate-specificity. The C12 mAb significantly inhibited EGFR phosphorylation in cancer cell lines by hindering the cleavage of EGFR ligands tethered to the cell surface. This inhibition provides a mechanism for potential anti-tumor effects, and indeed C12 diminished the viability of a variety of EGFR-expressing cancer cell lines. Cell-based ELISA studies revealed that C12 preferentially bound to activated ADAM17 present on tumor cells, as compared to the autoinhibited ADAM17 that is the predominant form on HEK293 and other non-tumor cells. C12 also exhibited tumor growth inhibition in an ovarian cancer xenograft mouse model. Consistent with its selective tumor cell binding in vitro, radioimmuno PET (positron emission tomography) imaging with 89 Zr-DFO-C12 in mouse xenograft models confirmed tumoral accumulation of the C12 mAb., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Malignant cells exhibit a high demand for amino acids to sustain their abnormal proliferation. Particularly, the intracellular accumulation of cysteine is often observed in cancer cells. Previous studies have shown that deprivation of intracellular cysteine in cancer cells results in the accumulation of lipid peroxides in the plasma membrane and induction of ferroptotic cell death, indicating that cysteine plays a critical role in the suppression of ferroptosis. Herein, we found that the oncogenic accumulation of cysteine also contributes to cancer cell proliferation by promoting the cell cycle progression, which is independent of its suppressive effect on ferroptosis. The growth ability of four types of cancer cells, including murine hepatocarcinoma cells, but not of primary hepatocytes, were dependent on the exogenous supply of cysteine. Deprivation of intracellular cysteine in cancer cells induced cell cycle arrest at the G0/G1 phase, accompanied by a decrease in the expression of cyclin D1 and D2 proteins. The cysteine deprivation-induced decrease in D-type cyclin expression was associated with the upregulation of eukaryotic translation initiation factor 4E binding protein 1, which represses the translation of cyclin D1 and D2 proteins by binding to eukaryotic translation initiation factor 4E. Similar results were observed in hepatocarcinoma cells treated with erastin, an inhibitor of cystine/glutamate antiporter, xCT. These findings reveal an unappreciated role of cysteine in regulating the growth of malignant cancer cells and deepen our understanding of the cytotoxic effect of xCT inhibitor to prevent cancer cell proliferation., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Mass spectrometry-based sample multiplexing with isobaric tags permits the development of high-throughput and precise quantitative biological assays with proteome-wide coverage and minimal missing values. Here, we nearly doubled the multiplexing capability of the TMTpro reagent set to a 35-plex through the incorporation of one deuterium isotope into the reporter group. Substituting deuterium frequently results in suboptimal peak coelution, which can compromise the accuracy of reporter ion-based quantification. To counteract the deuterium effect on quantitation, we implemented a strategy that necessitated the segregation of nondeuterium and deuterium-containing channels into distinct subplexes during normalization procedures, with reassembly through a common bridge channel. This multiplexing strategy of "design independent sub-plexes but acquire together" (DISAT) was used to compare protein expression differences between human cell lines and in a cysteine-profiling (i.e., chemoproteomics) experiment to identify compounds binding to cysteine-113 of Pin1.