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Neurodevelopment and neuronal function are modulated by multiple factors including environment,genetics and epigenetics.As a post-translational modification,N-glycosylation is catalyzed by glycosyltransferase and involves in diverse biological processes.N-glycosylation is abundant in neuronal system,regulates the development and maturation of synapse,and inflammatory response of glial cells.The dysregulation of N-glycosylation induces neurological disorders including Alzheimer's disease,congenital disorders of glycosylation,schizophrenia and epilepsy.In the present review,we have summarized the progresses of N-glycosylation in regulating neuronal and astrocytic function,and its roles in neurological disorders and related mechanisms.
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Pancreatic cancer is among the most malignant cancers, and thus early intervention is the key to better survival outcomes. However, no methods have been derived that can reliably identify early precursors of development into malignancy. Therefore, it is urgent to discover early molecular changes during pancreatic tumorigenesis. As aberrant glycosylation is closely associated with cancer progression, numerous efforts have been made to mine glycosylation changes as biomarkers for diagnosis; however, detailed glycoproteomic information, especially site-specific N-glycosylation changes in pancreatic cancer with and without drug treatment, needs to be further explored. Herein, we used comprehensive solid-phase chemoenzymatic glycoproteomics to analyze glycans, glycosites, and intact glycopeptides in pancreatic cancer cells and patient sera. The profiling of N-glycans in cancer cells revealed an increase in the secreted glycoproteins from the primary tumor of MIA PaCa-2 cells, whereas human sera, which contain many secreted glycoproteins, had significant changes of glycans at their specific glycosites. These results indicated the potential role for tumor-specific glycosylation as disease biomarkers. We also found that AMG-510, a small molecule inhibitor against Kirsten rat sarcoma viral oncogene homolog (KRAS) G12C mutation, profoundly reduced the glycosylation level in MIA PaCa-2 cells, suggesting that KRAS plays a role in the cellular glycosylation process, and thus glycosylation inhibition contributes to the anti-tumor effect of AMG-510.
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Humans , Glycosylation , Pancreatic Neoplasms/pathology , Adenocarcinoma , Proto-Oncogene Proteins p21(ras)/metabolism , Glycoproteins , Mass Spectrometry , Biomarkers/metabolism , PolysaccharidesABSTRACT
O-linked N-acetylglucosamine glycosylation (O-GlcNAcylation) is a protein post- translational protein formed by O-linked acetylglucosamine and serine/threonine residues on intracellular proteins. O-GlcNAc glycosylation modification is ubiquitous in the brain and is closely related to transcription, translation and protein homeostasis. O-GlcNAc glycosylation modification is involved in the occurrence and development of various neurological degenerative diseases, but its regulatory mechanism remains unclear. This paper reviews the relationship between O-GlcNAc glycosylation modification and neurological degenerative diseases.
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Endo-beta-N-acetylglucosaminidase (ENGase) is widely distributed in various organisms. The first reported ENGase activity was detected in Diplococcus pneumoniae in 1971. The protein (Endo D) was purified and its peptide sequence was determined in 1974. Three ENGases (Endo F1-F3) were discovered in Flavobacterium meningosepticum from 1982 to 1993. After that, the activity was detected from different species of bacteria, yeast, fungal, plant, mice, human, etc. Multiple ENGases were detected in some species, such as Arabidopsis thaliana and Trichoderma atroviride. The first preliminary crystallographic analysis of ENGase was conducted in 1994. But to date, only a few ENGases structures have been obtained, and the structure of human ENGase is still missing. The currently identified ENGases were distributed in the GH18 or GH85 families in Carbohydrate-Active enZyme (CAZy) database. GH18 ENGase only has hydrolytic activity, but GH85 ENGase has both hydrolytic and transglycosylation activity. Although ENGases of the two families have similar (β/α)8-TIM barrel structures, the active sites are slightly different. ENGase is an effective tool for glycan detection andglycan editing. Biochemically, ENGase can specifically hydrolyze β‑1,4 glycosidic bond between the twoN-acetylglucosamines (GlcNAc) on core pentasaccharide presented on glycopeptides and/or glycoproteins. Different ENGases may have different substrate specificity. The hydrolysis products are oligosaccharide chains and a GlcNAc or glycopeptides or glycoproteins with a GlcNAc. Conditionally, it can use the two products to produce a new glycopeptides or glycoprotein. Although ENGase is a common presentation in cell, its biological function remains unclear. Accumulated evidences demonstrated that ENGase is a none essential gene for living and a key regulator for differentiation. No ENGase gene was detected in the genomes of Saccharomyces cerevisiae and three other yeast species. Its expression was extremely low in lung. As glycoproteins are not produced by prokaryotic cells, a role for nutrition and/or microbial-host interaction was predicted for bacterium produced enzymes. In the embryonic lethality phenotype of the Ngly1-deficient mice can be partially rescued by Engase knockout, suggesting down regulation of Engase might be a solution for stress induced adaptation. Potential impacts of ENGase regulation on health and disease were presented. Rabeprazole, a drug used for stomach pain as a proton inhibitor, was identified as an inhibitor for ENGase. ENGases have been applied in vitro to produce antibodies with a designated glycan. The two step reactions were achieved by a pair of ENGase dominated for hydrolysis of substrate glycoprotein and synthesis of new glycoprotein with a free glycan of designed structure, respectively. In addition, ENGase was also been used in cell surface glycan editing. New application scenarios and new detection methods for glycobiological engineering are quickly opened up by the two functions of ENGase, especially in antibody remodeling and antibody drug conjugates. The discovery, distribution, structure property, enzymatic characteristics and recent researches in topical model organisms of ENGase were reviewed in this paper. Possible biological functions and mechanisms of ENGase, including differentiation, digestion of glycoproteins for nutrition and stress responding were hypothesised. In addition, the role of ENGase in glycan editing and synthetic biology was discussed. We hope this paper may provide insights for ENGase research and lay a solid foundation for applied and translational glycomics.
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Protein as the allergens could lead to allergy. In addition, a widespread class of allergens were known as glycans of N-glycoprotein. N-glycoprotein contained oligosaccharide linked by covalent bonds with protein. Recently,studies implicated that allergy was associated with glycans of heterologous N-glycoprotein found in food, inhalants, insect toxins, etc. The N-glycan structure of N-glycoprotein allergen has exerted an influence on the binding between allergens and IgE, while the recognition and presentation of allergens by antigen-presenting cells (APCs) were also affected. Some researches showed thatN-glycan structure of allergen was remodeled by N-glycosidase, such as cFase I, gpcXylase, as binding of allergen and IgE partly decreased. Thus, allergic problems caused by N-glycoproteins could potentially be solved by modifying or altering the structure ofN-glycoprotein allergens, addressing the root of the issue. Mechanism of N-glycans associated allergy could also be elaborated through glycosylation enzymes, alterations of host glycosylation. This article hopes to provide a separate insight for glycoimmunology perspective, and an alternative strategy for clinical prevention or therapy of allergic diseases.
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Objective To investigate the expression of(glutathione S-Transferase Omega-1,GSTO1)in cervical cancer tissue and its correlation with patient survival time,and to explore the impact of GSTO1 N-glycosylation on proliferation,migration,invasion,and epithelial-mesenchymal transition of cervical cancer.Methods By using immunohistochemistry,the expression levels of GSTO1 in tumor cells of 82 cervical cancer patients were detected,and the correlation between GSTO1 expression and clinical pathological features was analyzed.Kaplan-Meier meth-od was used to plot survival curves and evaluate the impact of GSTO1 expression in cervical cancer tissues on pa-tient survival time.Univariate and multivariate Cox regression analyses were performed to assess the independent prognostic factors influencing cervical cancer prognosis.The NetNGlyc 1.0 Server database predicted potential N-glycosylation modification sites of GSTO1(Asn55,Asnl35,Asn190).The cervical cancer cells(HeLa)were transfected with GSTO1 N-glycosylation site mutation vectors at positions 55,135,and 190,as well as GSTO1 wild-type vector and empty vector.Stable transfected cells were selected using puromycin.Western blot experi-ments were performed to assess the effectiveness of lentiviral interference.The effects of GSTO1 N-glycosylation site mutations on proliferation,migration,and invasion of HeLa cells were evaluated using EdU proliferation assay,wound healing assay,and Transwell assay.The effect of GSTO1 N-glycosylation site mutations on the epithelial-mesenchymal transition of HeLa cells was detected using the Western blot experiment.Results Immunohistochem-istry results revealed high expression of GSTO1 in cervical cancer tissues.The expression rate of GSTO1 was signifi-cantly higher in cervical cancer tissues with deep stromal invision≥1/2,lymphovascular space invasion,and lymph node metastasis(P<0.05).Moreover,high expression of GSTO1 was associated with poorer overall surviv-al.After N-glycosylation site-specific mutation of GSTO1,the cell count of proliferation,migration,and invasion in HeLa cells significantly decreased(P<0.05).The Western blot results showed that N-glycosylation site mutation of GSTO1 significantly inhibited the epithelial-mesenchymal transition of HeLa cells.Conclusion The expression of GSTO1 in cervical cancer tissues is associated with stromal infiltration depth,lymphovascular space invasion and lymph node metastasis,and it is also correlated with shorter patient survival time.Site-specific mutations in GSTO1 N-glycosylation significantly inhibit the proliferation,migration and epitheli al-mesenchymal transition of HeLa cells.
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Objective To investigate the effect of tonifying kidney and promoting pharynx prescription on IgA nephropathy model rats and the mechanism of regulating the TLR4 signaling pathway.Methods After SD rats were randomly divided into groups,the rat model of IgA nephropathy was replicated.After the medication,urinary RBC,UTP,blood creatinine,urea nitrogen,renal tissue TLR4,MyD88,NF-κB,MCP-1 expression,C1GALT1 and cosmoc mRNA expression in peripheral blood,TLR4,NF-κB and IL-6 in serum were observed.Results ①Compared with the blank group,urinary RBC,UTP,and renal tissue TLR4,MyD88 and NF-κB,MCP-1 expression,C1GALT1 and cosmoc mRNA expression in peripheral blood,TLR4,NF-κB and IL-6 in serum increased in the model group(P<0.05).②Compared with the model group,UTP,urinary RBC,renal tissue TLR4,MyD88 and NF-κB,MCP-1 expression,C1GALT1 and cosmoc mRNA expression in peripheral blood,the content of TLR4 and NF-κB,IL-6 were decreased(P<0.05)in tonifying kidney and promoting pharynx prescription group;There was no significant change in renal function.Conclusions ①The tonifying kidney and promoting pharynx prescription can effectively reduce hematuria and proteinuria in rats with IgA nephropathy.②The tonifying kidney and promoting pharynx prescription can reduce renal injury by improving the immune response mediated by TLR4 Signal transduction system induced by mucosal infection and reducing abnormal glycosylation IgA1 by adjusting key enzyme C1GalT1 and molecular companion Cosmc in IgA1 glycosylation process.
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Mannose phosphate isomerase-congenital disorders of glycosylation (MPI-CDG) is a treatable congenital genetic metabolic disease caused by the pathogenic variation of the gene encoding MPI.It is mainly manifested as diarrhea, hepatomegaly, hypoglycemia, and coagulation dysfunction.This review described the pathogenesis, clinical manifestations, genotypes, diagnosis, treatment and management of MPI-CDG, aiming to enhance the understanding of MPI-CDG.
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Abstract We aimed to characterize the clinical spectrum of patients diagnosed with SRD5A3-CDG, a subtype of congenital disorders of glycosylation (CDG) due to variants in the steroid 5a-reductase type 3 (SRD5A3) gene. It presents with multi-systemic involvement including neurological disability, dermatologic abnormalities, and ophthalmological defects. We conducted a cross-sectional study of children (n=6, ages 4-16 years) with a confirmed diagnosis of SRD5A3-CDG (c.57G>A, p.W19X). Families completed a detailed medical history questionnaire, two quality of life measures, and an adaptive behavior scale. Prevalent clinical features in our cohort included visual impairment (6/6), developmental delay (6/6), nystagmus (5/6), retinal dystrophy (4/6), and hypotonia (3/6). The Vineland Adaptive Behavior Scales demonstrated deficits across all functional domains (Composite Mean 36.17 ± 26.88), although one child did not show significant deficits. The QI-Disability Form demonstrated a mean total score of 64.8 (±12.7), and the PedsQL-Family Impact Module demonstrated a mean total score of 56.5 (±31.5). Vineland composite scores did not correlate with levels of disability captured by the QI-Disability Form (Pearson Correlation range -0.63 to +0.69, p>0.05 on all subscales). Ultimately, despite genotypic homogeneity, there is notable variability in adaptive functioning and quality of life among affected children that does not correlate with age.
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Abstract Congenital muscular dystrophies (CMDs) are inherited, progressive and heterogeneous muscle disorders. A group of CMDs are dystroglycanopathies, also called α-dystroglycanopathies, where there is an abnormal glycosylation of protein α-dystroglycan. Hypoglycosylation of α-DG results in different severities of congenital muscular dystrophies and they present with progressive muscle weakness and loss of motor functions. This article first focuses on the CMDs, their classification according to the observed symptoms or the protein involved in the resulting phenotype. We then focus on dystroglycanopathies, the importance of its correct O-glycosylation of the α-dystroglycan given its important structural function, considering the enzymes involved in said glycosylation and the phenotypes that can result, to finally address current therapeutics for these diseases with the aim of increasing current knowledge.
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In carbohydrate chemistry, the stereoselective synthesis of 1,2-cis-glycosides remains a formidable challenge. This complexity is comparable to the synthesis of 1,2-cis-β-D-mannosides, primarily due to the adverse anomeric and Δ-2 effects. Over the past decades, to attain β-stereoselectivity in D-rhamnosylation, researchers have devised numerous direct and indirect methodologies, including the hydrogen-bond-mediated aglycone delivery (HAD) method, the synthesis of β-D-mannoside paired with C6 deoxygenation, and the combined approach of 1,2-trans-glycosylation and C2 epimerization. This review elaborates on the advancements in β-D-rhamnosylation and its implications for the total synthesis of tiacumicin B and other physiologically relevant glycans.
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Glycosides , Mannosides , Glycosylation , StereoisomerismABSTRACT
@#Objective To optimize the expression of recombinant human growth hormone-Fc(rhGH-Fc)fusion protein in CHO cells in order to obtain better glycosylation ratio and lower content of highmannose.Methods CHO cells expressing rhGH-Fc were cultured in a 7 L bioreactor.The glycosylation modifications of rhGH-Fc were adjusted by improving the composition of feeding media(using three commercial media:Gly-1:EX-CELL Glycosylation Adjust,Gly-2:SHEFF-CHO PLUS PG ACF and Gly-3:EfficientFeed C + AGT Supplement & GlycanTune C + Total Feed),and the glycosylation type and proportion of the target proteins were analyzed by mass spectrometry.Results The G0F(main glycosylation types:G0,G1 and G2;F:fucose)of Gly-1,Gly-2 and Gly-3 were 32.89%,58.66% and 33.28%,the G1F were 31.39%,18.03%and 34.90%,and the G2F were 31.39%,18.03% and 34.90%,respectively.Gly-1 and Gly-3 made the target protein contain less G0F while more G2F;Gly-3 feeding scheme-showed less high mannose modification than the other two schemes.Conclusion Gly-1 medium changed the glycosylation modification from G0F to G1F and G2F,while Gly-2 medium changed that from G2F and G1F to G0F.However,Gly-3 medium changed the glycosylation modification from G0F to G1F and G2F,and the contentof high mannose was less than 5%,which may have a better effect on modifying glycosylation type and proportion of the target protein.
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Phosphomannomutase 2 deficiency is the most common form of N-glycosylation disorders and is also known as phosphomannomutase 2-congenital disorder of glycosylation (PMM2-CDG). It is an autosomal recessive disease with multi-system involvements and is caused by mutations in the PMM2 gene (OMIM: 601785), with varying severities in individuals. At present, there is still no specific therapy for PMM2-CDG, and early identification, early diagnosis, and early treatment can effectively prolong the life span of pediatric patients. This article reviews the advances in the diagnosis and treatment of PMM2-CDG.
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Humans , Child , Congenital Disorders of Glycosylation/therapy , MutationABSTRACT
Galectin-3 (Gal-3) belongs to the galectin family and is specific in binding β-galactoside. Through its C-terminal domain, Gal-3 binds to the galactoside group of the glycosylated insulin receptor (IR) and inhibits IR signaling pathway, which leads to the insulin resistance. Thus, Gal-3 is a potential therapeutic target for the treatment of insulin resistance and type 2 diabetes. Here we report a simple Gal-3 screening model based on the property that Gal-3 binds to the galactoside. We expressed and purified human Gal-3 in Escherichia coli (E.coli), and labeled it with fluorescein isothiocyanate (FITC) in vitro. After incubating FITC labeled Gal-3 (Gal-3-FITC) with PANC-1 cells, which express glycosylated membrane protein, PANC-1 cells started to show green fluorescent signal due to the Gal-3-FITC binding to the glycosylated membrane protein. Gal-3 inhibitor disrupts the binding of Gal-3-FITC and PANC1 cells, subsequently leads to the decrease of the fluorescent signal in PANC-1 cells. We can evaluate the inhibitory efficiency of Gal-3 inhibitors through measurement of the fluorescent signal. Further studies show this model is simple, stable, and repeatable with a Z' factor between 0.7 and 0.85. In sum, we have successfully established an in vitro high-throughput screening model for Gal-3 inhibitors.
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This study aimed to assess the hypoglycemic activity, and in vitro inhibition of α-glucosidase, inhibition of the advanced glycation end products (AGEs), and total antioxidant capacity were used to clarify its bioactivity. Furthermore, the potential hypoglycemic active chemical constituents in the aqueous extract of Osmanthus fragrans var. thunbergii flower were characterized using high performance liquid chromatography-electrospray ionization-quadruple time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS) method. The result showed that in vitro inhibition of α-glucosidase of the extract (IC50 = 2.11 ± 0.26 mg·mL-1) were similar to acarbose (IC50 = 2.88 ± 0.32 mg·mL-1), and it inhibited the AGEs formation and the total antioxidant capacity in a certain extent. Based on the MS fragmentation pathway analysis of reference chemical acteoside contained in this extract, and related references, 73 constituents were tentatively identified from the aqueous extract of Osmanthus fragrans var. thunbergii flower, including 58 phenylethanoids, 8 caffeoylquinic acids, 1 flavonoid vicenin-2, and 6 common organic chemicals in plant. Furthermore, 8 unknown alkaloids were characterized in this work. Among of these chemicals, 61 phenylethanoids were supposed to be detected for the first time. In conclusion, this work disclosed the potential hypoglycemic active constituents of Osmanthus fragrans var. thunbergii flower.
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@#N-linked glycosylation is a common post-translational modification on proteins, which exhibits the same macro-heterogeneity of modification site as other small molecule modifications (such as methylation, acetylation, phosphorylation), i.e., the amino acid sequence of a protein has multiple putative modification sites. However, compared to small molecule modifications with single structures, N-glycosylation modification have tens of thousands of structures from multiple structural dimensions such as different monosaccharide compositions, sequence structures, linking structures, isomerism, and three-dimensional conformation.This results in additional micro-heterogeneity of modification site of N-glycosylation, i.e., the same N-glycosylation site can be modified with different glycans with a certain stoichiometric ratio.N-glycosylation modification regulates the structure and function of N-glycoproteins in a site- and structure-specific manner, and differential expression of N-glycosylation under disease conditions needs to be characterized through site- and structure-specific quantitative analysis.This article mainly introduces the latest development of mass spectrometry-based site- and structure-specific quantitative N-glycoproteomics and its applications in biomedical fields.
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@#Glycosylation of proteins, one of the most prevalent and complex post-translational modifications occurring in nature, plays a crucial role in regulating protein net charge, conformation, binding properties and, ultimately, biological function.Traditional structural techniques are not amenable for glycoproteins due to the inherent heterogeneity of oligosaccharides.With the advances in analytical technique, mass spectrometry displays an increasingly crucial role in elucidating the structure of glycoproteins.Mass spectrometry-based proteomic technique can dissect the chemical composition and site information of low-abundance glycosylation at the peptide level.Instead, native mass spectrometry (nMS) can analyze intact glycoproteins while maintaining the information for glycan heterogeneity, and the insights into the regulatory effects of glycosylation on protein higher order structures and interactions with other proteins or ligands.As a representative structural mass spectrometry tool, ion mobility-based nMS strategy is powered by its conformer-resolving capability and by the feasibility of conformer manipulation through collision-induced unfolding.Consequently, native IM-MS analysis can provide rich information of dynamic protein conformations, allowing for the rapid identification and differentiation of protein isoforms in an unprecedented manner.In this review, we briefly introduced two emerging native IM-MS analytical modes, dynamic conformer-resolving mode and glycoform-resolving mode.Besides, we also discussed the recent progress of conformational and topological characterization of intact glycoproteins with three typical model systems based on two above-mentioned emerging modes of native IM-MS.
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Objective:To summarize the clinical manifestations, gene variations, diagnosis and treatment of 3 cases with SLC35A2 variations characterized by congenital glycosylation disorder Ⅱm (CDG Ⅱm). Methods:A total of 3 patients admitted to the Department of Pediatrics of Xiangya Hospital of Central South University in China from 2018 to 2020 were examined in detail. The studies till January 2022 were searched with key words of "congenital disorders of glycosylation Ⅱm", " SLC35A2" and "CDG Ⅱm" in both English and Chinese in the databases of China National Knowledge Infrast Ructure (CNKI), Wanfang, Online Mendelian Inheritance in Man and PubMed, and the clinical manifestations, genetic variation, treatments and prognosis of patients with SLC35A2 mutation were summarized. Results:The patients all presented with intractable infantile spasm and global developmental delay, onset in infancy. A variety of antiepileptic treatments had temporary and partial efficacy. Otherwise, proband 2 and 3 presented with abnormal glutamic-pyruvic transaminase and increased platelets. Funduscopy showed dysplasia of the retinal pigment epithelium in both eyes, and they both received D-galactose treatment. A total of 22 relevant case reports, including 99 patients, were collected. The 99 patients all were heterozygous mutations, and a total of 75 different variation sites were reported. The clinical manifestations were characterized by global developmental delay or mental retardation ( n=89), epileptic seizure ( n=75), hypotonia ( n=57), facial deformity ( n=57), skeletal abnormality ( n=50), visual impairment ( n=42), elevated glutamic-pyruvic transaminase ( n=31), gastrointestinal symptoms ( n=28), skin deformity ( n=26), microcephaly ( n=23) and congenital heart disease ( n=12). Craniocerebral magnetic resonance imaging may be normal in the early stage. With age, magnetic resonance imaging may show abnormal white matter signals, brain atrophy, dysplasia of corpus callosum, delayed myelination, enlargement of lateral ventricle, brain stem atrophy and so on. Studies have shown that galactose treatment may be effective. Conclusions:SLC35A2 variants lead to CDG Ⅱm, whose clinical manifestations mainly include epileptic encephalopathy and global developmental delay. Multiple antiepileptic therapies can temporarily or partially control seizures, while oral galactose may improve the clinical symptoms, showing its prospect as a dietary therapy.
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Farnesoid X receptor (FXR) is a nuclear receptor activated by bile acid that is involved in regulating gene expression related to bile acid, fat, glucose, and amino acid metabolism. The activity of FXR is regulated by a variety of post-translational modifications. Common post-translational modifications of FXR include O-GlcNAcylation, phosphorylation, acetylation, sumoylation, methylation, etc. These post-translational modifications may affect FXR binding of DNA and ligand, heterodimerization, and subcellular localization, and may specifically regulate downstream gene transcription and expression. Different post-translational modifications can lead to changes in FXR stability and biological function, which are closely related to the occurrence of diseases. This paper aims to review the post-translational modification of FXR in the past five years and the mechanisms involved in disease regulation, to explore the effects of post-translational modification on the physiological function of FXR and to provide a theoretical basis for mechanism research targeting FXR.
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Neuropathic pain is a common chronic pain that affects human health worldwide. As an important mediator of excitatory conduction in neurons, ion channels are important targets for mechanism research and drug research in this field. T-type calcium channel(Cav3) can be activated transiently when neurons are close to the resting potential of -70 mV, resulting in a transient Ca