Mechanism of DNA methylation-mediated downregulation of O6-methylguanine-DNA methyltransferase in cartilage injury of Kashin-Beck disease.

OBJECTIVE: Kashin-Beck disease (KBD) is an endemic osteoarthropathy, in which excessive apoptosis of chondrocytes occurs. O6-methylguanine-DNA methyltransferase (MGMT), a DNA damage repair gene, plays an important role in apoptosis, but the mechanism is unclear in KBD cartilage injury. This study was to investigate the expression and promoter methylation of MGMT in KBD patients and its role in DNA damage and apoptosis of chondrocytes. METHODS: MGMT mRNA and protein level were detected by quantitative real-time PCR and immunohistochemistry. Demethylation of MGMT was carried out using 5-Aza-2'-deoxycytidine, and the methylation level of MGMT promoter was measured by quantitative methylation specific PCR. Next, small hairpin RNA was used to knockdown the expression of MGMT. Cell viability, apoptosis and DNA damage were determined by MTT assay, flow cytometry, Hoechst 33342 staining and alkaline comet assay following T-2 toxin and selenium treatment. RESULTS: MGMT protein expression and mRNA levels were decreased (P = 0.02, P = 0.007) and promoter methylation was increased (P = 0.008) in KBD patients. Meanwhile, MGMT level was upregulated by 5-Aza-2'-deoxycytidine in chondrocytes (P = 0.0002). DNA damage and apoptosis rates were increased in MGMT-silenced chondrocytes (all P < 0.0001). Furthermore, DNA damage and apoptosis were increased in chondrocytes treated with T-2 toxin (all P < 0.0001), but were decreased after selenium treatment (P < 0.0001, P = 0.01). Decreased mRNA level and increased methylation of MGMT were found in the T-2 toxin group (P = 0.005, P = 0.002), while selenium reversed it (P = 0.02, P = 0.004). CONCLUSIONS: MGMT might play a crucial part in the pathogenesis of KBD cartilage injury, which could provide a therapeutic target for KBD.

An eQTL variant of ALDH1A2 is associated with Kashin-Beck disease in Chinese population.

INTRODUCTION: The aims of the study were to investigate the relationship between aldehyde dehydrogenase 1 family member A2 (ALDH1A2) and Kashin-Beck disease (KBD), explore the effects of the rs3204689 polymorphism and methylation status on the expression levels of ALDH1A2, and further clarify the pathogenesis of KBD. MATERIALS AND METHODS: The genotype of ALDH1A2 rs3204689 was detected by PCR-RFLP in 103 KBD patients and 109 healthy controls in the whole blood. The mRNA level of ALDH1A2 was measured by qRT-PCR, and the protein expression was detected using IHC staining and Western blotting. The MSP-PCR was used to identify the ALDH1A2 methylation level. RESULTS: There were significant differences in G/G, G/C, and C/C frequencies of ALDH1A2 rs3204689 between the KBD and control groups (χ2 = 7.113, P = 0.029); the minor allele G of ALDH1A2 was associated with the risk of KBD (χ2 = 5.984, P = 0.014). The mRNA and protein levels of ALDH1A2 were increased in the whole blood and cartilage of KBD patients compared with the controls (P = 0.049, P < 0.0001, P = 0.019). Meanwhile, a statistically significant difference was observed between G/G, G/C and C/C genotype on mRNA expression (P = 0.039). The methylation level of the ALDH1A2 gene promoter region showed no significant difference between the KBD and control groups (χ2 = 0.317, P = 0.573). CONCLUSION: Our case-control study indicates that the common variant rs3204689 near ALDH1A2 is associated with KBD in Chinese population. The risk allele G of rs3204689 is statistically linked to the high expression of ALDH1A2, which is up-regulated in the cartilage and whole blood of KBD patients. Our findings suggest a potential role of ALDH1A2 in the pathogenesis of KBD.

Crosstalk between CpG Methylation and Polymorphisms (CpG-SNPs) in the Promotor Region of DIO2 in Kashin-Beck Disease.

Objective This study was designed to determine the methylation profile of four CpGs and the genotypes of two CpG-SNPs located in promoter region of DIO2 in patients with Kashin-Beck disease (KBD). We also analyzed the interaction between the CpGs methylations and CpG-SNPs. Methods Whole blood specimens were collected from 16 KBD patients and 16 healthy subjects. Four CpGs and two CpG-SNPs in the promoter regions of DIO2 were detected using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The CpGs methylation levels were compared between samples from KBD patients and healthy subjects. The methylation levels were also analyzed in KBD patients with different CpG-SNP genotypes. Results The mRNA expression of DIO2 in whole blood of KBD patients was significnatly lower than in healthy controls (P <0.05). The methylation levels of DIO2-1_CpG_3 in KBD patients were significantly higher than those in healthy controls (P <0.05). The methylation levels of four CpGs were not significantly different between KBD patients and healthy controls. The methylation level of DIO2-1_CpG_3 in the promoter region of DIO2 in KBD patients with GA/AA genotype was significantly higher than that of KBD patients with GG genotype (P <0.05). Conclusion The methylation level of DIO2 increases in KBD patients. Similar trends exist in KBD carriers of variant genotypes of CpG-SNPs DIO2 rs955849187.

[Expression and Regulatory Mechanism of Autophagy-related Genes in Synovial Tissues of Patients with Rheumatoid Arthritis].

Objective To investigate the expression regulation of autophagy-related genes(ATG)and the mechanism of autophagy in rheumatoid arthritis(RA).Methods The differentially expressed genes(DEG)of RA were identified from GSE55235 and GSE55457,on the basis of which the differentially expressed autophagy-related genes(DE-ATG)were selected from the Human Autophagy Database.STRING 11.0 and GeneMANIA were used to establish protein-protein interaction networks.Further,the transcription factor-gene-miRNA co-expression network was established via NetworkAnalyst and Cytoscape.Finally,receiver operating characteristic(ROC)curve and DrugBank were employed to evaluate the efficacy of the predicted biomarkers and the performance of drugs targeting DE-ATG.GraphPad Prism 8.2.1 and R 4.0.3 were used for statistical analysis and graphics.Results A total of 485 DEG were enriched in signaling pathways such as T cell activation,hormone regulation,osteoclast differentiation,RA,and chemokines.Eleven DE-ATG regulated the expression of RUNX1,TP53,SOX2,and hsa-mir-155-5p in synovial tissues of RA patients and were involved in the response to environmental factors such as 2,3,7,8-tetrachlorodibenzodioxin and silicon dioxide.The ROC curve analysis identified the DE-ATG with good sensitivity and specificity,such as MYC,MAPK8,CDKN1A,and TNFSF10,which can be used to distinguish certain phenotypes and serve as novel biomarkers for RA.Conclusions In RA,down-regulated DE-ATG expression may promote apoptosis and lysis of chondrocytes.The identified novel biomarkers provides new ideas and methods for diagnosing and treating RA.The establishment of transcription factor-miRNA-gene co-expression network provides direct evidence for dissecting synovial inflammation and articular cartilage destruction.

Effects of methylation of deiodinase 3 gene on gene expression and severity of Kashin-Beck disease.

Kashin-Beck disease (KBD) is a complex endemic osteoarthropathy, which mainly occurs in the northeast to southwest China. Iodothyronine deiodinases 3 (DIO3) is one of the selenoproteins, which is closely related to bone metabolism and unclear to KBD. This study aims to investigate the role and associated mechanisms of methylation and expression of DIO3 with disease severity in patients with KBD. We performed a bioinformatics analysis first to identify the biological mechanisms involved in selenoproteins. The methylation status of the DIO3 gene and DIO3 gene expression, as well as DIO3-related regulatory genes in patients with KBD, were analyzed. We found that 15 CpG sites of six selenoproteins were hypomethylated with 5-azacytidine treatment. DIO3 hypermethylation was associated with an increased risk of KBD and may lead to downregulation of DIO3 gene expression as well as be an indicator of the severity of KBD, which may provide a new insight for gene-environment correlations and interactions in etiology and pathogenesis of KBD.

Potential candidate biomarkers associated with osteoarthritis: Evidence from a comprehensive network and pathway analysis.

Osteoarthritis (OA) is one of the most common forms of arthritis world widely. Some key genes and diagnostic markers have been reported due to the development of modern molecular biology technologies. However, the etiology and pathogenesis of OA remains unknown. In this study, an integrated network and pathway analysis towards the biological function of OA-associated genes was conducted to provide valuable information to further explore the etiology and pathogenesis of OA. A total of 2,548 genes which reported a statistically significant association with OA were screened. An integrated network and pathway analysis was performed to identify the pathways and genes most associated to OA. Moreover, OA-specific protein-protein interaction (PPI) network was constructed by cytocluster based on the Molecular Complex Detection Algorithm (MCODE) to screen its candidate biomarkers. Quantitative real-time polymerase chain reaction was used to confirm the expression levels and to validate the results of MCODE cluster analysis by six genes. The pathway networks suggested that extracellular matrix (ECM) organization, collagen degradation and collagen formation showed important associations with OA. In top two PPI clusters, 61 of the OA-associated genes were included in the OA-specific PPI network, which also included 23 candidate genes that are likely to be highly associated with OA based on MCODE clusters. Analysis of mRNA showed that the expression levels of COL9A1, COL9A2, ITGA3, COL9A3, ITGA2, and LAMA1 in the peripheral blood mononuclear cells of OA patients were significantly lower than those of the normal controls (p<0.005). To our knowledge, this is the first comprehensive and systematic report based on OA-related genes demonstrating that the functional destruction of collagen in cartilage may be a very important contributing factor to OA. Quantitative detection of collagen synthesis may be of great help in early identification and prediction of OA. Maintaining the quality and quantity of collagen can be a potential target for clinical treatment of OA in the future practice.

Analysis of gene expression and methylation datasets identified ADAMTS9, FKBP5, and PFKBF3 as biomarkers for osteoarthritis.

BACKGROUND: Osteoarthritis (OA) is a kind of chronic osteoarthropathy and degenerative joint disease. Epigenetic regulation in the gene expression dynamics has become increasingly important in OA. We performed a combined analysis of two types of microarray datasets (gene expression and DNA methylation) to identify methylation-based key biomarkers to provide a better understanding of molecular biological mechanisms of OA. METHODS: We obtained two expression profiling datasets (GSE55235, GSE55457) and one DNA methylation profiling data set (GSE63695) from the Gene Expression Omnibus. First, differentially expressed genes (DEGs) between patients with OA and controls were identified using the Limma package in R(v3.4.4). Then, function enrichment analysis of DEGs was performed using a DAVID database. For DNA methylation datasets, ChAMP methylation analysis package was used to identify differential methylation genes (DMGs). Finally, a comprehensive analysis of DEGs and DMGs was conducted to identify genes that exhibited differential expression and methylation simultaneously. RESULTS: We identified 112 DEGs and 2,896 DMGs in patients with OA compared with controls. Functional analysis of DEGs obtained that inflammatory responses, immune responses, and positive regulation of apoptosis, tumor necrosis factor (TNF) signaling pathway, and osteoclast differentiation may be involved in the pathogenesis of OA. Cross-analysis revealed 26 genes that exhibited differential expression and methylation in OA. Among them, ADAMTS9, FKBP5, and PFKBF3 were identified as valuable methylation-based biomarkers for OA. CONCLUSION: In summary, our study identified different molecular features between patients with OA and controls. This may provide new clues for clarifying the pathogenetic mechanisms of OA.

Epidemic pattern of hand-foot-and-mouth disease in Xi'an, China from 2008 through 2015.

BACKGROUND: Hand, foot and mouth disease (HFMD) is an infectious disease caused by enteroviruses that has a severely impair for those high incidence countries such as China.The current study aimed to investigate the epidemic pattern of HFMD by time and region in Northwestern China. METHODS: All reported HFMD cases from 2008 to 2015 were collected from local Disease Control and Prevention.The HFMD was diagnosed in accordance with the guidebook provided by the National Health and Family Planning Commission of the People's Republic of China. RESULTS: A total of 154,869 cases of probable HFMD were reported. The overall incidence of HFMD has been increased from 91.68 per 100/000 in 2008 to 335.64 per 100/000 in 2015.The case mortality is decreased from 0.014 per100/000 to 0.011 per 100/000 during the time period. Most HFMD (93.82%) occurred in children younger than 5 years. The seasonal peak of HFMD infections occurred in April-July and September-November and Central regions of Xi'an city were the major locations of the clusters (incidence rate 245.75/100,000; relative risk 1.19, P < 0.01). EVA71 was the predominant enterovirus serotype, accounting for 50.0% of all reported HFMD cases since 2011.The most susceptible group infected by HFMD was children younger than 5 years, especially boys. CONCLUSIONS: Incidence of HFMD has been increasing in the past few years, however, the case fatality is decreasing. Season and region shall be considered as influence factors in the prevention of HFMD.

The expression of ERK and JNK in patients with an endemic osteochondropathy, Kashin-Beck disease.

Kashin-Beck disease (KBD) is a chronic, endemic osteochondropathy. Its etiopathogenesis is still obscure until now. Epidemiological observation has shown that low selenium play a crucial role in the pathogenesis of KBD. Extracellular signal-regulated kinases (ERKs) and C-Jun N-terminal kinase (JNK), members of the mitogen-activated protein kinase (MAPK) superfamily, play an important role in cell proliferation and differentiation. Nuclear factor-ĸB (NF-ĸB), an important signaling mediator for inflammatory and immune responses, is involved in the regulation of osteoclastogenesis. In the present study, we investigated the expression of ERK and JNK signal molecular, as well as nuclear factor-ĸB in the pathogenesis of Kashin-Beck disease, evaluated the effect of selenium on ERK signal pathway. The expression levels of ERK and JNK signal pathway, as well as nuclear factor-ĸB were investigated for 218 patients and 209 controls by immunoblot analysis in whole blood. Evaluated the effect of selenium on ERK signal pathway by Na2SeO3 treatment. The protein levels of pRaf-1, pMek1/2 and pErk1/2 decreased significantly in KBD patients, p-JNK and NF-ĸB increased in KBD patients. Furthermore, Na2SeO3 treatment improved the reduction of proteins in ERK signal pathway. These findings indicated that ERK and JNK signaling pathways, as well as the expression level of NF-κB signaling molecular are important contributor to the pathogenesis of KBD. Selenium stimulates the phosphorylation of the ERK signaling pathway.

Effects of sodium selenite on c-Jun N-terminal kinase signalling pathway induced by oxidative stress in human chondrocytes and c-Jun N-terminal kinase expression in patients with Kashin-Beck disease, an endemic osteoarthritis.

The c-Jun N-terminal kinases (JNK) are members of the mitogen-activated protein kinase family and are activated by environmental stress. Se plays an important role in the biological pathways by forming selenoprotein. Selenoproteins have been shown to exhibit a variety of biological functions including antioxidant functions and maintaining cellular redox balance, and compromise of such important proteins would lead to oxidative stress and apoptosis. We examined the expression levels of JNK in Kashin-Beck disease (KBD) patients, tested the potential protective effects of sodium selenite on tert-butyl hydroperoxide (tBHP)-induced oxidative injury and apoptosis in human chondrocytes as well as its underlying mechanism in this study. We produced an oxidative damage model induced by tBHP in C28/I2 human chondrocytes to test the essential anti-apoptosis effects of Se in vitro. The results indicated that the expression level of phosphorylated JNK was significantly increased in KBD patients. Cell apoptosis was increased and molecule expressions of the JNK signalling pathway were activated in the tBHP-injured chondrocytes. Na2SeO3 protected against tBHP-induced oxidative stress and apoptosis in cells by increasing cell viability, reducing reactive oxygen species generation, increasing Glutathione peroxidase (GPx) activity and down-regulating the JNK pathway. These results demonstrate that apoptosis induced by tBHP in chondrocytes might be mediated via up-regulation of the JNK pathway; Na2SeO3 has an effect of anti-apoptosis by down-regulating the JNK signalling pathway.

Expression of m6A Methylation Regulator in Osteoarthritis and Its Prognostic Markers.

OBJECTIVE: Osteoarthritis (OA) is a multifactorial disorder, in which genetic factors are strongly associated with its development. However, the pathogenesis of OA is still unclear, and recently it has been observed that epigenetic modifications are also involved in the pathogenesis of OA. This study aims to study the potential role of m6A-related genes in the occurrence and development of OA. DESIGN: We downloaded the OA expression profile data (GSE55235) from the Gene Expression Omnibus database. First, function enrichment analysis of 17 representative m6A methylation regulatory factors was performed using the DAVID database and Metascape online tool. Then, we analyzed the expression of 17 m6A methylation regulatory factors in OA and the correlation between regulatory factors using Perl software. Finally, receiver operating characteristic (ROC) curve analysis and the area under the ROC curve were used to evaluate the diagnostic effectiveness of m6A-related genes for discriminating patients with OA and healthy. RESULTS: We first identified that 12 of the 17 genes were differentially expressed in OA. ALKBH1, EIF3, IGF2BP3, WTAP, and YTHDC1 were associated with early diagnosis and prognosis of OA. CONCLUSIONS: m6A RNA methylation regulator factors are key players in the progression of OA and have potential role in the stratification of prognosis and the formulation of treatment strategies.

The Role of Selenium-Mediated Notch/Hes1 Signaling Pathway in Kashin-Beck Disease Patients and Cartilage Injury Models.

Kashin-Beck disease (KBD) is a nutrition-related osteoarthropathy, and selenium (Se) deficiency is an environmental risk factor for KBD. Notch/Hes1 signaling pathway plays a vital role in regulating cartilage, but its exact mechanisms in KBD remain unknown. The Se contents were determined using the hydride atomic fluorescence spectrometry assay technique, and the mRNA levels were detected via quantitative real-time PCR. The chondrocyte injury models were established by Se deficiency and tert-butyl hydroperoxide (tBHP), respectively; apoptosis and necrosis rates were detected using Hoechst 33,342/PI and Annexin V-FITC/PI. The results showed that the Se levels in the flour of KBD areas were lower than that of the non-KBD areas, and the Se levels in the plasma of KBD patients were lower than that of the controls. The expressions of Notch1, Jagged1, and Hes1 were higher in the whole blood of KBD patients than those of the controls, and Notch1 was negatively correlated with the expression of BCL2, while was positively correlated with BAX. In injury, chondrocytes induced by low Se and tBHP, the expression of Notch1, Jagged1, and Hes1 increased, apoptosis and necrosis rates increased in Se deficiency and tBHP groups, while Se supplementation reversed it. Decreased plasma Se in KBD patients may be related to low dietary Se. Se deficiency might be involved in the pathological process of KBD by activating the Notch/Hes1 signaling pathway to induce excessive apoptosis of chondrocytes, the activation of Notch/Hes1 promotes oxidative injury, and Se supplementation could reverse it. The importance of Notch/Hes1 signaling pathway in KBD development will provide a new potential target for KBD.

Dysregulation of Transcription Profile of Selenoprotein in Patients with Kashin-Beck Disease and Its Effect on Se Deficiency-Induced Chondrocyte Apoptosis.

Kashin-Beck disease (KBD) is a chronic, degenerative osteoarthropathy related to selenium (Se) deficiency. Se participates in the synthesis of selenoprotein in the form of selenocysteine. In total, 25 selenoproteins, encoded by 25 genes, are currently found in humans; however, the effects of selenoprotein genes on chondrocyte apoptosis, particularly in apoptosis-related genes, remain poorly elucidated. Therefore, in the current study, the expression of selenoprotein genes and apoptosis-related genes were determined by RT-qPCR in patients and chondrocytes and the correlations between them were analyzed using Pearson and Spearman's rank correlation, and the chondrocyte apoptosis rate was detected by Annexin V-FITC/PI. The results showed that the mRNA levels of 17 selenoprotein genes were downregulated, whereas two genes were upregulated in patients with KBD. The BAX/BCL2 ratio and the mRNA levels of BAX and P53 were increased, but the mRNA levels of BCL2 and NF-κB p65 were decreased in patients with KBD. The mRNA levels of GPX2, GPX3, DIO1, TXNRD1, TXNRD3, and SPS2 were most closely associated with apoptosis-related genes in patients with KBD. Moreover, in the Se deficiency group, the mRNA levels of GPX3, DIO1, and TXNRD1 were downregulated and GPX activity was decreased, but the late apoptosis rate, the mRNA levels of BAX and P53, and the BAX/BCL2 ratio were increased; the opposite trend was observed in the Se supplement group. Collectively, these results indicate that selenoprotein transcription profile is dysregulated in patients with KBD. Furthermore, the expression of GPX3, DIO1, and TXNRD1 genes might be involved in the development of chondrocyte apoptosis by affecting antioxidant capacity.

Gene and prognostic value of N6-methyladenosine (m6A) modification regulatory factors in lung adenocarcinoma.

Lung cancer is the leading cause of death worldwide, and its incidence continues to increase. The treatment of lung cancer is related to the subtypes and stages of cancer, but the therapeutic effect is still unsatisfactory. We found that 10 of the 13 genes were differentially expressed in lung cancer, YTHDF1, RBM15, HNRNPC, KIAA1429, METTL3 and YTHDF2 are high expression while METTL14, ZC3H13, FTO and WTAP are low expression. HNRNPC and METTL3 genes were associated with the risk and prognosis of LUAD and could regard as biomarkers for early diagnosis and treatment, which provides a theoretical basis for LUAD.

CpG methylation of the GPX3 promoter in patients with Kashin-Beck Disease potentially promotes chondrocyte apoptosis.

OBJECTIVE: To determine the methylation levels of CpGs in the GPX3 promoter region and explore their potential effects on the apoptosis of chondrocytes. METHODS: Blood specimens were collected from 32 participants; 16 KBD patients and 16 healthy subjects. Twenty-five CpGs in the promoter region of GPX3 were identified and detected by MALDI-TOF-MS. Methylation levels of CpGs were compared between KBD patients and healthy subjects as well as among the KBD patients with different degrees. C28/I2 human chondrocytes were treated with tBHP and Na2SeO3. Apoptosis in chondrocytes was examined under a fluorescence microscope. RESULTS: The methylation levels of GPX3-1_CpG_11 and GPX3-1_CpG_16 in KBD patients were significantly higher than those of healthy subjects (P < 0.05). The methylation levels of the other CpGs were not significantly different between the two groups (P > 0.05). The methylation level of GPX3-1_CpG_24 in KBD patients was significantly higher than those of healthy subjects (P < 0.05). MSP-PCR analysis indicated that the methylation rate of KBD group (9.41%) was significantly higher than that of healthy subjects (1.18%), and that GPX3 DNA methylation increased the risk of acquiring KBD 8 fold (OR = 8.000, 95% CI: 1.023-62.580); The mRNA expression of GPX3 in whole blood of KBD patients was lower than that of healthy subjects (P＜0.05); Compared with the control group, GPX3, GPX1 and GPX4 mRNA level of the tertbutyl hydroperoxide injury group decreased significantly (P < 0.05), after supplementation with Na2SeO3. The rate of chondrocytes apoptosis was decreased with the increasing of GPX3 and GPX4 mRNA levels (P＜0.05) and GPX3 mRNA showed a similar trend without statistically significant (P＞0.05). CONCLUSION: The methylation patterns of CpGs in GPX3 varied in KBD patients. The experiments indicated that the increased methylation of CpGs within the GPX3 promoter may down-regulate the expression of GPX3, thereby reducing the antioxidant function of GPX3 and promoting chondrocyte apoptosis, both of which accelerates the occurrence of KBD. We therefore propose a new understanding of GPX3's potential epigenetic and genetic mechanisms that contribute to KBD.

Patients with Osteoarthritis and Kashin-Beck Disease Display Distinct CpG Methylation Profiles in the DIO2, GPX3, and TXRND1 Promoter Regions.

OBJECTIVE: We aimed to analyze deoxycytidine-deoxyguanosine dinucleotide (CpGs) methylation profiles in DIO2, GPX3, and TXNRD1 promoter regions in osteoarthritis (OA) and Kashin-Beck disease (KBD) patients. METHODS: Blood samples were collected from 16 primary OA patients and corresponding 16 healthy individuals and analyzed for methylations in the CpGs of DIO2, GPX3, and TXNRD1 promoter regions using MALDI-TOF-MS. The methylation profiles of these regions were then compared between OA and KBD patients. RESULTS: DIO2-1_CpG_2 and DIO2-1_CpG_3 methylations were significantly lower in OA than KBD patients (P < 0.05). A similar trend was observed for GPX3-1_CpG_4, GPX3-1_CpG_7, GPX3-1_CpG_8.9.10, GPX3-1_CpG_13.14.15 and GPX3-1_CpG_16 (P < 0.05) as well as TXNRD1-1_CpG_1 and TXNRD1-1_CpG_2 methylation between OA and KBD patients (P < 0.05). However, there was no difference in methylation levels of other CpGs between the 2 groups (P > 0.05). CONCLUSION: OA and KBD patients display distinct methylation profiles in the CpG sites of DIO2, GPX3, and TXNRD1 promoter regions. These findings provide a strong background and new perspective for future studies on mechanisms underlying epigenetic regulation of selenoprotein genes associated with OA and KBD diseases.

Selenoprotein P gene r25191g/a polymorphism and quantification of selenoprotein P mRNA level in patients with Kashin-Beck disease.

Kashin-Beck disease (KBD) is an endemic and deformable osteoarthrosis. Epidemiological study has revealed that lower Se level is the principal environmental factor in the pathogenesis of KBD. Selenoprotein P (SEPP1) is a special selenoprotein, which is the primary form of Se in vivo. Our aim was to investigate the putative association of SEPP1 r25191g/a single nucleotide polymorphism (SNP) with KBD risk and the SEPP1 transcriptional levels in whole blood and articular cartilage tissue of KBD cases and controls, respectively. One hundred and sixty-seven cases with KBD and 166 control subjects from Shaanxi province of China were included in the present study. The detection of SNP r25191g/a in the 3' untranslated region was performed using an efficient technique, tetra-primer amplification refractory mutation system PCR. A quantitative analysis of SEPP1 mRNA in KBD and control groups by real-time PCR was also performed. The present results show no significant difference in genotype and allele distribution of SNP r25191g/a between individuals with KBD and controls (P = 0·279 and 0·428, respectively). There was also no association between SNP r25191g/a and risk of KBD (OR 1·153; 95 % CI 0·533, 2·496). However, the frequency of the rare genotype AG of SNP r25191g/a was significantly lower in Chinese population than in the Caucasians. It was shown that the SEPP1 mRNA expression in whole blood was lower in KBD patients than in the control group (0·149-fold, P < 0·001), but that it was much higher in articular cartilage tissue (4·53-fold, P = 0·012). Our aim was to lay a foundation for us to further study the association between the pathogenesis of KBD and SEPP1.

Identification of differentially expressed and methylated genes associated with rheumatoid arthritis based on network.

Rheumatoid arthritis (RA) is a multi-systemic inflammatory autoimmune disease involving peripheral joints, and the pathogenesis is not clear. Studies showed that DNA methylation and expression might also be involved in the pathogenesis of RA. This study integrated three expression profile datasets (GSE55235, GSE12021, and GSE55457) and one methylation profile dataset GSE111942 to elucidate the potential essential candidate genes and pathways in RA. Differentially expressed genes (DEGs) and differentially methylation genes (DMGs) were identified by R programming software, using Limma package and ChAMP package, respectively. DAVID performed gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs. Functional annotation and construction of a protein-protein interaction (PPI) network and the Molecular Complex Detection Algorithm (MCODE) were analysed by STRING and Cystoscope, respectively. Then the connection analysis of DEGs and DMGs was carried out, and further to analyse the relationship between methylation and gene expression, aiming to screen out the potential genes. In this study, 288 DEGs and 228 DMGs were identified, and the majority of DEGs were up-regulated. Enrichment analysis represented that DEGs mainly involved immune response and participated in the Cytokine-cytokine receptor interaction signal pathway. 282 nodes were identified from DEGs PPI network and MCODE, filtering the most significant 2 modules, 23 core node genes were identified and most of them are involved in the T cell receptor signalling pathway and chemokine-mediated signalling pathway. Cross-analysis revealed 4 genes [KNTC1 (cg 01277763), LRRC8D (cg 07600884), DHRS9 (cg 05961700), and UCP2 (cg 05205664)] that exhibited differential expression and methylation in RA simultaneously. Therefore, the four genes could be used as the target for RA.

Dystrophin glycoprotein complex-associated Gbetagamma subunits activate phosphatidylinositol-3-kinase/Akt signaling in skeletal muscle in a laminin-dependent manner.

Previously, we showed that laminin-binding to the dystrophin glycoprotein complex (DGC) of skeletal muscle causes a heterotrimeric G-protein (Galphabetagamma) to bind, changing the activation state of the Gsalpha subunit. Others have shown that laminin-binding to the DGC also leads to Akt activation. Gbetagamma, released when Gsalpha is activated, is known to bind phosphatidylinositol-3-kinase (PI3K), which activates Akt in other cells. Here, we investigate whether muscle Akt activation results from Gbetagamma, using immunoprecipitation and immunoblotting, and purified Gbetagamma. In the presence of laminin, PI3K-binding to the DGC increases and Akt becomes phosphorylated and activated (pAkt), and glycogen synthase kinase is phosphorylated. Antibodies, which specifically block laminin-binding to alpha-dystroglycan, prevent PI3K-binding to the DGC. Purified bovine brain Gbetagamma also caused PI3K and Akt activation. These results show that DGC-Gbetagamma is binding PI3K and activating pAkt in a laminin-dependent manner. Mdx mice, which have greatly diminished amounts of DGC proteins, display elevated pAkt signaling and increased expression of integrin beta1 compared to normal muscle. This integrin binds laminin, Gbetagamma, and PI3K. Collectively, these suggest that PI3K is an important target for the Gbetagamma, which normally binds to DGC syntrophin, and activates PI3K/Akt signaling. Disruption of the DGC in mdx mouse is causing dis-regulation of the laminin-DGC-Gbetagamma-PI3K-Akt signaling and is likely to be important to the pathogenesis of muscular dystrophy. Upregulating integrin beta1 expression and activating the PI3K/Akt pathway in muscular dystrophy may partially compensate for the loss of the DGC. The results suggest new therapeutic approaches to muscle disease.

[Expression of PI3K/Akt signal pathway in acute myocardial ischemia].

OBJECTIVE: To explore the influence of the PI3K/Akt-mediated signal pathway in acute myocardial ischemia (AMI) rats, the expression of pAkt, Akt, Caspase3 and p38 in myocardium and somatic muscles of AMI rats were detected. METHODS: The rats model of AMI were established by peritoneal injecting isoprinosine (ISO), and were detected by electrocardiogram and haemodynamics. The expressions of pAkt, Caspase3 and p38 in somatic muscles and cardiac muscles of AMI and normal rats were detected by Dot blot hybridization and Western blot. RESULTS: In contrast with normal rats, electrocardiogram of AMI rats showed a lower displacement of ST segment (> or = 0.1 mv). The expression of pAkt, Caspase3 and p38 were higher than those in normal rats (P < 0.05). No apparent changes were observed in expression of Akt (P = 0.477). CONCLUSION: Expressions of pAkt, Akt and correlated apoptosis molecule Caspase3 and p38 in cardiac and somatic muscles of AMI rats were higher than those in normal rats. No apparent changes were observed in expression of Akt.