Levels of base excision repair proteins in CD4+ T cells in patients with systemic lupus erythematosus / 中南大学学报(医学版)

OBJECTIVES@#Systemic lupus erythematosus (SLE) is a multi-systemic disease with the unknown pathogenic mechanism. DNA demethylation is involved in SLE pathogenesis. Growth arrest and DNA damage inducible 45 alpha (Gadd45a) takes part in the process of DNA demethylation. Gadd45a is a DNA repair-related protein. This study aims to investigate the expressions of some proteins [including activation-induced cytidine deaminase (AID), thymine DNA glycosylase (TDG), and methyl-CpG-binding domain protein 4 (MBD4)] involving in base excision repair (BER) process in CD4+ T cells in patients with SLE, and to analyze the correlations between the above BER proteins and lupus disease.@*METHODS@#From January 2019 to September 2020, 12 SLE patients and 12 healthy controls were recruited from Second Xiangya Hospital of Central South University. Peripheral blood mononuclear cells (PBMCs) were separated by Ficoll-Hypaque density gradient centrifugation and then CD4+ T cells were isolated via positive selection using Miltenyi beads. We measured the messenger RNA (mRNA) and protein expressions of AID, TDG, and MBD4 by real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blotting, respectively.@*RESULTS@#In contrast to controls, in SLE CD4+ T cells, the mRNA and protein expressions of AID were elevated (P=0.003, P=0.022, respectively); TDG protein expression was increased (P=0.017); and MBD4 protein level was reduced (P<0.001). No visible distinctions was found in the mRNA expressions of either TDG or MBD4 between the 2 groups (both P>0.05). The mRNA and protein expressions of AID and the protein levels of TDG were positively correlated with SLE disease activity index (SLEDAI). And the mRNA and protein expressions of MBD4 were negatively correlated with SLEDAI.@*CONCLUSIONS@#In SLE CD4+ T cells, the increased expressions of AID and TDG and the decreased MBD4 expression may participate in SLE pathogenic mechanism.

Clinical characteristics of acute myeloid leukemia patients with TET2 gene mutation and effects of TET2 mutation on therapeutic efficacy and prognosis / 白血病·淋巴瘤

Objective:To investigate clinical features of adult patients with acute myeloid leukemia (AML) with TET2 gene mutation and effects of TET2 mutation on therapeutic efficacy and prognosis.Methods:A total of 123 newly diagnosed adult AML patients (except for acute promyelocytic leukemia) admitted to Jining No.1 People's Hospital from March 2017 to April 2021 were selected. Mutations of 24 AML-related genes including TET2 mutation were detected by using second-generation sequencing technology. Patients were divided into two groups according to the presence of TET2 mutation: TET2 mutation group and TET2 wild type group. The differences in clinicopathological characteristics, short-term efficacy and survival of both groups were compared.Results:Among 123 patients, TET2 mutation was detected in 28 cases (22.8%). Compared with TET2 wild type group, the patients were older [(59±15) years vs.(49±16) years, t = 2.984, P = 0.003], French-American-British (FAB) Corporative Group M 4 and M 5 subtypes were more common [75.0% (21/28) vs. 51.6% (49/95), χ2 = 4.838, P = 0.028], and the positive rate of CD34 in AML patients was lower in TET2 mutation group [46.4% (13/28) vs.72.6% (69/95), χ2 = 6.685, P = 0.010]. Moreover, TET2 mutation was more likely to be accompanied with ZRSR2 mutation [10.7% (3/28) vs. 1.1% (1/95), P = 0.037] and NPM1 mutation [35.7% (10/28) vs.17.9% (17/95), χ2 = 4.008, P = 0.045], but less likely to be accompanied with IDH1/2 mutation [0 vs.17.9% (17/95), P = 0.012]. However, there were no statistically significant differences in gender, peripheral blood leukocyte count at initial diagnosis, hemoglobin level, platelet count, bone marrow blasts ratio, cytogenetics and the European LeukemiaNet (ELN) risk stratification between the two groups (all P>0.05). In addition, there were no significant differences in the overall response rate (ORR) of 1 cycle chemotherapy [75.0% (12/16) vs. 66.7% (42/63), χ2 = 0.410, P = 0.522] and demethylation therapy [66.7% (4/6) vs. 44.4% (8/18), P = 0.640]. The difference in overall survival (OS) of both groups was not statistically significant [median OS time: 23 months (95% CI 5-41 months) vs. 35 months (95% CI 18-52 months, P = 0.498]. Conclusions:In AML patients, TET2 mutation is associated with advanced age, M 4 and M 5 subtypes, and low expression of CD34 on AML blasts. TET2 mutation is commonly accompanied by ZRSR2 and NPM1 mutation, but not IDH1 or IDH2 mutation. TET2 mutation may have no significant effects on therapeutic efficacy and survival in the whole cohort of AML patients without risk stratification.

The function and regulation of TET2 in innate immunity and inflammation

TET2, a member of ten-eleven translocation (TET) family as α-ketoglutarate- and Fe

Effects of 5-azacytidine on DNA methylation and index components in patchouliol-type Pogostemon cablin / 中国中药杂志

This study aims to explore the relationship of DNA methylation with the contents of the index components as well as the growth and development of Pogostemon cablin. The demethylation reagent 5-azacytidine(5-azaC) was used to treat the tissue culture seedlings of patchouliol-type P. cablin. High performance liquid chromatography was employed to evaluate the changes of DNA methy-lation in P. cablin, and GC-MS to detect the contents of index components in P.cablin. The agronomic characters of P.cablin were measured using the common methods. The results showcased that DNA methylation of P.cablin was significantly reduced by 5-azaC in a concentration-dependent manner. Thirty days after treatment with 5-azaC at different concentrations, the content of patchouli alcohol changed slightly; compared with that in the control group, the content of pogostone in 50 μmol·L~(-1) and 100 μmol·L~(-1) 5-azaC groups was significantly up-regulated. The 100 μmol·L~(-1) 5-azaC group had the largest differences in contents of pogostone and patchouli alcohol compared with the control group, followed by the 50 μmol·L~(-1) 5-azaC group. Ninety days after disinhibition, the content of pogostone in the treatment group was significantly increased and the content of patchouli alcohol was significantly decreased. In addition, 5-azaC significantly inhibited the growth and development of P.cablin in a dose-dependent manner. These results indicate that DNA methylation regulates the biosynthesis of the index components in patchouliol-type P.cablin and proper demethylation can directly promote the synthesis of pogostone and indirectly affect the accumulation of patchouli alcohol.

Research progress of histone lysine demethylase KDM5A in tumors / 肿瘤

Histone methylation is one of the important research contents of epigenetics. Methylation of histones is dynamically regulated by histone methylase and histone demethylase. Histone lysine (K) demethylase 5A (KDM5A) is an important member in the histone demethylase family, which can specifically remove the dimethyl and trimethyl from the 4th lysine of histone H3 (H3K4me2/3), thus mediating gene silencing and regulating cell function. KDM5A can directly or indirectly maintain tumor cell dryness, inhibit cell metabolism and differentiation, promote tumor cell proliferation, metastasis and drug resistance, so it is closely related to the occurrence, development and drug resistance of various tumors. KDM5A may become a new potential target for the diagnosis and treatment of tumors.

Role of TET3-induced DNA demethylation in methane-induced up-regulation of Nrf2 expression in rat spinal cord neurons subjected to oxygen-glucose deprivation and restoration injury / 中华麻醉学杂志

Objective To evaluate the role of TET3-induced DNA demethylation in methane-in-duced up-regulation of nuclear factor-erythroid 2-related factor 2 ( Nrf2) expression in rat spinal cord neu-rons subjected to oxygen-glucose deprivation and restoration ( OGD∕R) injury. Methods The primarily cultured spinal cord neurons of rats were seeded in 6-well plates at a density of 1×105 cells∕ml and divided into 5 groups ( n=48 each) using a random number table method: control group ( group C) , group OGD∕R, methane group (group M), methane plus TET3-siRNA group (group M+siTET3) and methane plus negative siRNA group (group M+siCon). The medium was replaced with glucose- and serum-free Earle's salt solution, and the neurons were exposed to 5％ CO2-95％N2 in an incubator for 2 h followed by routine culture to establish the model of OGD∕R. In group M, 200μl methane-saturated saline ( final concentration of methane 1. 8 mmol∕L) was added at oxygen-glucose restoration. TET3-siRNA 100 pmol∕L and negative siRNA 100 pmol∕L were added at 24 h before oxygen-glucose restoration to perform transfection in M+siTET3 and M+siCon groups, respectively. At 12 h of oxygen-glucose restoration, the neuronal survival rate, release rate of lactic dehydrogenase ( LDH) and apoptotic rate of neurons were measured, and the ex-pression of TET3 and Nrf2 protein and mRNA was detected by Western blot and fluorescent quantitative re-al-time polymerase chain reaction, respectively, and contents of superoxide dismutase (SOD), catalase ( CAT) and malonaldehyde ( MDA) were measured by enzyme-linked immunosorbent assay. Neuronal DNA was extracted for determination of methylation and hydroxymethylation rates of DNA ( by enzyme-linked im-munosorbent assay) and methylation of CpG island in Nrf2 gene promoter ( by fluorescent real-time methyla-tion specific polymerase chain reaction). Results Compared with group C, the survival rate of neurons was significantly decreased, the release rate of LDH and apoptotic rate were increased in group OGD∕R ( P<0. 01) . Compared with OGD∕R, the survival rate of neurons was significantly increased, the release rate of LDH and apoptotic rate were decreased, the expression of TET3 and Nrf2 protein and mRNA was up-regula-ted, DNA hydroxymethylation rate and contents of SOD and CAT were increased, and the DNA and Nrf2 promoter methylation rates and MDA content were decreased in group M ( P<0. 05 or 0. 01) . Compared with group M, the neuronal survival rate was significantly decreased, the release rate of LDH and apoptotic rate were increased, the expression of TET3 and Nrf2 protein and mRNA was down-regulated, the DNA hydroxymethylation rate and contents of SOD and CAT were decreased, and the DNA and Nrf2 promoter methylation rates and MDA content were increased in group M+siTET3 ( P<0. 05 or 0. 01) , and no signifi-cant change was found in the parameters mentioned above in group M+siCon ( P>0. 05) . Conclusion The mechanism by which methane up-regulates Nrf2 expression in rat spinal cord neurons subjected to OGD∕R injury is related to activating TET3 and promoting DNA demethylation in Nrf2 promoter.

Tet: novel anti-tumor drug target based on DNA demethylation / 上海交通大学学报（医学版）

Tet (ten-eleven translocation) proteins belong to α-ketoglutaric acid (α-KG or 2-OG) and Fe2+ dependent dioxygenases. Tets are found to be involved in the unique mammalian DNA active demethylation process by specifically oxidizing the methyl group of 5-methylcytosine (5mC) in mammalian genome, and play critical roles in gene regulation in early embryonic development and stem cell differentiation via regulating the dynamic balance distribution of 5mC. Abnormal expression and function of Tets are closely associated with various hematological malignances, including myelodysplastic syndrome, chronic myelomonocytic leukemia, and acute lymphoblastic leukemia, as well as solid tumors. Hence, Tets and Tets-mediated DNA demethylation are novel anti-tumor drug targets. Investigation of biological function and catalytic mechanism of Tets is helpful for further understanding mechanisms of tumor incidence and development relevant to DNA demethylation pathway and can provide reference for developing new anti-tumor targeted drugs.

Progress in TET enzymes and their intermediate products / 中国病理生理杂志

DNA methylation is an important epigenetic modification mode , which plays a crucial role in gene expression , genome stability and development .DNA methylation is catalyzed and maintained in cell proliferation by the family of DNA methyltransferases.The ten-eleven translocation (TET) enzymes oxidize 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC).Here, we briefly describe the TET enzymes and their role in cancer , and the distribution , the role and detection method of those three oxidation products of cytosine in genome .

Role of DNA methylation in regulation of osteogenic differentiation of stem cells / 华西口腔医学杂志

DNA methylation and demethylation are two important mechanisms of epigenetics, which is important in the study of cell differentiation, proliferation, and senescence. During osteogenic differentiation of stem cells, the expression of osteogenic specific genes and demethylated promoters is upregulated, whereas the expression of pluripotent genes and hypermethylated promoters is downregulated. The dynamic changes and balance between DNA methylation and demethylation are important for the coordination of gene expression and the inhibition of improper phenotypes. Abnormal changes in the methylation modification mechanism in osteogenic differentiation not only affect the normal function of stem cells but are also associated with the occurrence and development of many common skeletal diseases. This paper reviews the new progress of DNA methylation and demethylation in regulating osteogenic differentiation. The possible skeletal diseases caused by abnormal DNA methylation are also presented.