The catalytic core of DEMETER guides active DNA demethylation in <i>Arabidopsis</i>

Zhang, Changqing,Hung, Yu-Hung,Rim, Hyun Jung,Zhang, Dapeng,Frost, Jennifer M.,Shin, Hosub,Jang, Hosung,Liu, Fang,Xiao, Wenyan,Iyer, Lakshminarayan M.,Aravind, L.,Zhang, Xiang-Qian,Fischer, Robert L. National Academy of Sciences 2019 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.116 No.35

<P><B>Significance</B></P><P>Flowering plants reproduce via a unique double-fertilization event, producing the zygote and the nutritive endosperm. The genome of the central cell, the precursor of the endosperm, undergoes extensive demethylation prior to fertilization. This epigenetic reconfiguration, directed by the DEMETER (DME) glycosylase at thousands of loci in <I>Arabidopsis</I>, differentiates the epigenetic landscapes of parental genomes and establishes parent of origin-specific expression of many imprinted genes in endosperm essential for seed development. However, how DME is targeted to various locations remains unknown. Here we show that the multidomain DME is organized into 2 functional regions: the C-terminal region, which guides localization and catalysis, and the N-terminal region, which likely recruits chromatin remodelers to facilitate demethylation within heterochromatin.</P><P>The <I>Arabidopsis</I> DEMETER (DME) DNA glycosylase demethylates the maternal genome in the central cell prior to fertilization and is essential for seed viability. DME preferentially targets small transposons that flank coding genes, influencing their expression and initiating plant gene imprinting. DME also targets intergenic and heterochromatic regions, but how it is recruited to these differing chromatin landscapes is unknown. The C-terminal half of DME consists of 3 conserved regions required for catalysis in vitro. We show that this catalytic core guides active demethylation at endogenous targets, rescuing <I>dme</I> developmental and genomic hypermethylation phenotypes. However, without the N terminus, heterochromatin demethylation is significantly impeded, and abundant CG-methylated genic sequences are ectopically demethylated. Comparative analysis revealed that the conserved DME N-terminal domains are present only in flowering plants, whereas the domain architecture of DME-like proteins in nonvascular plants mainly resembles the catalytic core, suggesting that it might represent the ancestral form of the 5mC DNA glycosylase found in plant lineages. We propose a bipartite model for DME protein action and suggest that the DME N terminus was acquired late during land plant evolution to improve specificity and facilitate demethylation at heterochromatin targets.</P>

Four active monomers from Moutan Cortex exert inhibitory effects against oxidative stress by activating Nrf2/Keap1 signaling pathway

Baoshun Zhang,Deqing Yu,Nanxuan Luo,Changqing Yang,Yurong Zhu 대한생리학회-대한약리학회 2020 The Korean Journal of Physiology & Pharmacology Vol.24 No.5

Paeonol, quercetin, β-sitosterol, and gallic acid extracted from Moutan Cortex had been reported to possess anti-oxidative, anti-inflammatory, and antitumor activities. This work aimed to illustrate the potential anti-oxidative mechanism of monomers in human liver hepatocellular carcinoma (HepG2) cells-induced by hydrogen peroxide (H₂O₂) and to evaluate whether the hepatoprotective effect of monomers was independence or synergy in mice stimulated by carbon tetrachloride (CCl₄). Monomers protected against oxidative stress in HepG2 cells in a doseresponse manner by inhibiting the generation of reactive oxygen species, increasing total antioxidant capacity, catalase and superoxide dismutase (SOD) activities, and activating the antioxidative pathway of nuclear factor E2-related factor 2/Kelchlike ECH-associated protein 1 (Nrf2/Keap1) signaling pathway. We found that the in vitro antioxidant capacities of paeonol and quercetin were better than those of -sitosterol and gallic acid. Furthermore, paeonol apparently diminished the levels of alanine transaminase and aspartate aminotransferase, augmented the contents of glutathione and SOD, promoted the expressions of Nrf2 and heme oxygenase-1 proteins in mice stimulated by CCl₄. In HepG2 cells, paeonol, quercetin, β-sitosterol, and gallic acid play a defensive role against H₂O₂-induced oxidative stress through activating Nrf2/Keap1 pathway, indicating that these monomers have anti-oxidative properties. Totally, paeonol and quercetin exerted anti-oxidative and hepatoprotective effects, which is independent rather than synergy.

Antioxidant and hepatoprotective activity of kaempferol 3-O-b-D- (2,6-di-O-a-L-rhamnopyranosyl)galactopyronoside against carbon tetrachloride-induced liver injury in mice

Yanqing Zang,Dongjie Zhang,Changqing Yu,Chenghao Jin,Kiharu Igarashi 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.4

This study aims to investigate the antioxidant and hepatoprotective effects of kaempferol 3-O-b-D- (2,6- di-O-a-L-rhamnopyranosyl)galactopyronoside (KG) isolated from unripe soybean leaves. Carbon tetrachloride (CCl4)-induced hepatotoxic ddY mice were used in the study. The mice were divided into three groups, namely the control group, the CCl4 group (CCl4, CCl4 injected), and the KG group (KG, CCl4 injected with KG administration). Hepatic injury markers of serum and liver were analyzed. The results show that serum ALT, AST activities, hepatic glutathione, superoxide dismutase, catalase, and glutathione peroxidase activities were normalized in mice pretreated with KG. Furthermore, the liver thiobarbituric acid reactive substances levels were found to be improved by pretreatment with KG, indicating that KG is available to alleviate liver injury, this may be due to its antioxidant properties. This study suggests that unripe soy leaves could be used as functional food materials.

Coupled irradiation-thermal-mechanical analysis of the solid-state core in a heat pipe cooled reactor

Yugao Ma,Jiusong Liu,Hongxing Yu,Changqing Tian,Shanfang Huang,Jian Deng,Xiaoming Chai,Yu Liu,Xiaoqiang He 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.6

The solid-state core of a heat pipe cooled reactor operates at high temperatures over 1000 K withthermal and irradiation-induced expansion during burnup. The expansion changes the gap thicknessbetween the solid components and the material properties, and may even cause the gap closure, whichthen significantly influences the thermal and mechanical characteristics of the reactor core. This studydeveloped an irradiation behavior model for HPRTRAN, a heat pipe reactor system analysis code, tointroduce the irradiation effects such as swelling and creep. The megawatt heat pipe reactor MegaPowerwas chosen as an application case. The coupled irradiation-thermal-mechanical model was developed tosimulate the irradiation effects on the heat transfer and stresses of the whole reactor core. The resultsshow that the irradiation deformation effect is significant, with the irradiation-induced strains up to2.82% for fuel and 0.30% for monolith at the end of the reactor lifetime. The peak temperatures during thelifetime are 1027:3 K for the fuel and 956:2 K for monolith. The gap closure enhances the heat transferbut caused high stresses exceeding the yield strength in the monolith

Glucocorticoid-induced expansion of classical monocytes contributes to bone loss

Liu Pei,Gao Youshui,Luo Pengbo,Yu Hongping,Guo Shang,Liu Fuyun,Gao Junjie,Xu Jianzhong,Wang Shengdian,Zhang Changqing 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Classical monocytes are commonly involved in the innate inflammatory response and are the progenitors of osteoclasts. Excess endogenous glucocorticoids (GCs) can increase the levels of classical monocytes in blood and bone marrow. The role of this cell population in high-dose exogenous GC-induced osteoporosis (GIOP) remains to be elucidated. In this study, GIOP was established in rats and mice by daily methylprednisolone injection, and monocyte subsets were analyzed by flow cytometry. We demonstrated that classical monocytes accumulate in bone marrow during GIOP. Similarly, the monocyte proportion among bone marrow nucleated cells was also increased in patients with steroid treatment history. We sorted classical monocytes and analyzed their transcriptional profile in response to GCs by RNA sequencing. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that classical monocytes isolated from GC-treated rats exhibited osteoclast differentiation potential. Deletion of classical monocytes by clodronate liposome treatment prevented GIOP via inhibition of osteoclastogenesis and restoration of CD31HiendomucinHi vessels. Regarding the molecular mechanism, classical monocytes express high levels of glucocorticoid receptors. In vitro treatment with GCs increased both the percentage and absolute number of monocytes and promoted their proliferation. In summary, classical monocytes mediated GC-induced bone loss and are a potential target for therapeutic intervention in GIOP treatment.

Assessment of the Cytotoxic and Apoptotic Effects of Chaetominine in a Human Leukemia Cell Line

Jing-Yun Yao,Ruihua Jiao,Changqing Liu,Yupeng Zhang,Wan-Guo Yu,Yan-Hua Lu,Renxiang Tan 한국응용약물학회 2016 Biomolecules & Therapeutics(구 응용약물학회지) Vol.24 No.2

Chaetominine is a quinazoline alkaloid originating from the endophytic fungus Aspergillus fumigatus CY018. In this study, we showed evidence that chaetominine has cytotoxic and apoptotic effects on human leukemia K562 cells and investigated the pathway involved in chaetominine-induced apoptosis in detail. Chaetominine inhibited K562 cell growth, with an IC50 value of 35 nM, but showed little inhibitory effect on the growth of human peripheral blood mononuclear cells. The high apoptosis rates, morphological apoptotic features, and DNA fragmentation caused by chaetominine indicated that the cytotoxicity was partially caused by its pro-apoptotic effect. Under chaetominine treatment, the Bax/Bcl-2 ratio was upregulated (from 0.3 to 8), which was followed by a decrease in mitochondrial membrane potential, release of cytochrome c from mitochondria into the cytosol, and stimulation of Apaf-1. Furthermore, activation of caspase-9 and caspase-3, which are the main executers of the apoptotic process, was observed. These results demonstrated that chaetominine induced cell apoptosis via the mitochondrial pathway. Chaetominine inhibited K562 cell growth and induced apoptotic cell death through the intrinsic pathway, which suggests that chaetominine might be a promising therapeutic for leukemia.

Assessment of the Cytotoxic and Apoptotic Effects of Chaetominine in a Human Leukemia Cell Line

Yao, Jingyun,Jiao, Ruihua,Liu, Changqing,Zhang, Yupeng,Yu, Wanguo,Lu, Yanhua,Tan, Renxiang The Korean Society of Applied Pharmacology 2016 Biomolecules & Therapeutics(구 응용약물학회지) Vol.24 No.2

Chaetominine is a quinazoline alkaloid originating from the endophytic fungus Aspergillus fumigatus CY018. In this study, we showed evidence that chaetominine has cytotoxic and apoptotic effects on human leukemia K562 cells and investigated the pathway involved in chaetominine-induced apoptosis in detail. Chaetominine inhibited K562 cell growth, with an $IC_{50}$ value of 35 nM, but showed little inhibitory effect on the growth of human peripheral blood mononuclear cells. The high apoptosis rates, morphological apoptotic features, and DNA fragmentation caused by chaetominine indicated that the cytotoxicity was partially caused by its pro-apoptotic effect. Under chaetominine treatment, the Bax/Bcl-2 ratio was upregulated (from 0.3 to 8), which was followed by a decrease in mitochondrial membrane potential, release of cytochrome c from mitochondria into the cytosol, and stimulation of Apaf-1. Furthermore, activation of caspase-9 and caspase-3, which are the main executers of the apoptotic process, was observed. These results demonstrated that chaetominine induced cell apoptosis via the mitochondrial pathway. Chaetominine inhibited K562 cell growth and induced apoptotic cell death through the intrinsic pathway, which suggests that chaetominine might be a promising therapeutic for leukemia.

Radiation Dose Reduction and Surgical Efficiency Improvement in Endoscopic Transforaminal Lumbar Interbody Fusion Assisted by Intraoperative O-arm Navigation: A Retrospective Observational Study

Junfeng Gong,Xinle Huang,Liwen Luo,Huan Liu,Hao Wu,Ying Tan,Changqing Li,Yu Tang,Yue Zhou 대한척추신경외과학회 2022 Neurospine Vol.19 No.2

Objective: Endoscopic transforaminal lumbar interbody fusion (Endo-TLIF) has gained increasing popularity among spine surgeons. However, with the use of fluoroscopy, intraoperative radiation exposure remains a major concern. Here, we aim to introduce Endo-TLIF assisted by O-arm-based navigation and compare the results between O-arm navigation and fluoroscopy groups. Methods: Sixty-four patients were retrospectively analyzed from May 2019 to September 2020; the nonnavigation group comprised 34 patients, and the navigation group comprised 30 patients. Data on radiation dose, blood loss, postoperative drains, surgery time, complications, and length of hospital stay (LOS) were collected. Clinical outcomes were evaluated from postoperative data such as fusion rate, Oswestry Disability Index (ODI), and visual analogue scale (VAS). Radiation dose and surgery time were selected as primary outcomes; the others were second outcomes. Results: All patients were followed up for at least 12 months. No significant differences were detected in intraoperative hemorrhage, postoperative drains, hospital LOS, or complications between the 2 groups. The radiation dose was significantly lower in the navigation group compared with the nonnavigation group. The time of cannula placement and pedicle screw fixation was significantly reduced in the navigation group. No significant differences were detected between the clinical outcomes in the 2 groups (VAS and ODI scores). Conclusion: The present study demonstrates that O-arm-assisted Endo-TLIF is efficient and safe. Compared with fluoroscopy, O-arm navigation could reduce the radiation exposure and surgical time in Endo-TLIF surgery, with similar clinical outcomes. However, the higher doses exposed to patients remains a negative effect of this technology.