BACKGROUND: Retinoid X receptor(RXR) plays a central role in the regulation of intracellular receptor signaling pathways. The activation of RXR has protective effect on H2O2-induced apoptosis of H9c2 ventricular cells...BACKGROUND: Retinoid X receptor(RXR) plays a central role in the regulation of intracellular receptor signaling pathways. The activation of RXR has protective effect on H2O2-induced apoptosis of H9c2 ventricular cells in rats. But the protective effect and mechanism of activating RXR in cardiomyocytes against hypoxia/reoxygenation(H/R)-induced oxidative iniury are still unclear.METHODS: The model of H/R injury was established through hypoxia for 2 hours and reoxygenation for 4 hours in H9c2 cardiomyocytes of rats. 9-cis-retinoic acid(9-cis RA) was obtained as an RXR agonist, and HX531 as an RXR antagonist. Cultured cardiomyocytes were randomly divided into four groups: sham group, H/R group, H/R+9-cis RA-pretreated group(100 nmol/L 9-cis RA), and H/R+9-cis RA+HX531-pretreated group(2.5 μmol/L HX531). The cell viability was measured by MTT, apoptosis rate of cardiomyocytes by flow cytometry analysis, and mitochondrial membrane potential(ΔΨm) by JC-1 fluorescent probe, and protein expressions of Bcl-2, Bax and cleaved caspase-9 with Western blotting. All measurement data were expressed as mean±standard deviation, and analyzed using one-way ANOVA and the Dunnett test. Differences were considered signif icant when P was <0.05.RESULTS: Pretreatment with RXR agonist enhanced cell viability, reduced apoptosis ratio, and stabled ΔΨm. Dot blotting experiments showed that under H/R stress conditions, Bcl-2 protein level decreased, while Bax and cleaved caspase-9 were increased. 9-cis RA administration before H/R stress prevented these effects, but the protective effects of activating RXR on cardiomyocytes against H/R induced oxidative injury were abolished when pretreated with RXR pan-antagonist HX531.CONCLUSION: The activation of RXR has protective effects against H/R injury in H9c2 cardiomyocytes of rats through attenuating signaling pathway of mitochondria apoptosis.展开更多
Some adult vertebrate species,such as newts,axolotls and zebrafish,have the ability to regenerate their central nervous system（CNS）.However,the factors that establish a permissive CNS environment for correct morphol...Some adult vertebrate species,such as newts,axolotls and zebrafish,have the ability to regenerate their central nervous system（CNS）.However,the factors that establish a permissive CNS environment for correct morphological and functional regeneration in these species are not well understood.Recent evidence supports a role for retinoid signaling in the intrinsic ability of neurons,in these regeneration-competent species,to regrow after CNS injury.Previously,we demonstrated that a specific retinoic acid receptor（RAR）subtype,RARβ,mediates the effects of endogenous retinoic acid（RA）on neuronal growth and guidance in the adult newt CNS after injury.Here,we now examine the expression of the retinoid X receptor RXRα（a potential heterodimeric transcriptional regulator with RARβ）,in newt tail and spinal cord regeneration.We show that at 21 days post-amputation（dpa）,RXRαis expressed at temporally distinct periods and in non-overlapping spatial domains compared to RARβ.Whereas RARβprotein levels increase,RXRαproteins level decrease by 21 dpa.A selective agonist for RXR,SR11237,prevents both this downregulation of RXRαand upregulation of RARβand inhibits tail and caudal spinal cord regeneration.Moreover,treatment with a selective antagonist for RARβ,LE135,inhibits regeneration with the same morphological consequences as treatment with SR11237.Interestingly,LE135 treatment also inhibits the normal downregulation of RXRαin tail and spinal cord tissues at 21 dpa.These results reveal a previously unidentified,indirect regulatory feedback loop between these two receptor subtypes in regulating the regeneration of tail and spinal cord tissues in this regeneration-competent newt.展开更多
All-trans retinoic acid (ATRA) triggers a wide range of effects on vertebrate development by regulating cell proliferation, differentiation, and apoptosis. ATRA activates retinoic acid receptors (RARs) which heterodim...All-trans retinoic acid (ATRA) triggers a wide range of effects on vertebrate development by regulating cell proliferation, differentiation, and apoptosis. ATRA activates retinoic acid receptors (RARs) which heterodimerize with retinoid X receptors (RXRs). RAR/RXR heterodimers function as ATRA-dependent transcriptional regulators by binding to retinoic acid response elements (RAREs). To identify RAR/RXR heterodimer-binding sites in the human genome, we performed a modified yeast one-hybrid assays and identified 193 RAR/RXR heterodimer-binding fragments in the human genome. The putative target genes included genes involved in development process and cell differentiation. Gel mobility shift assays indicated that 160 putative RAREs could directly interact with the RAR/RXR heterodimer. Moreover, 19 functional regulatory single nucleotide polymorphisms (rSNPs) on the RAR/RXR-binding sequences were identified by analyzing the difference in the DNA-binding affinities. These results provide insights into the molecular mechanisms underlying the physiological and pathological actions of RAR/RXR heterodimers.展开更多
A novel meroterpenoid,named meroterpenthiazole A(1),was isolated from the deep-sea-derived Penicillium allii-sativi.Its structure was established by extensive spectroscopic and computational methods.Meroterpenthiazole...A novel meroterpenoid,named meroterpenthiazole A(1),was isolated from the deep-sea-derived Penicillium allii-sativi.Its structure was established by extensive spectroscopic and computational methods.Meroterpenthiazole A bears a rare benzothiazole moiety in nature.Compound 1 significantly inhibited retinoid X receptor(RXR)-α transcriptional effect(K_(D)=12.3 μmol/L) through a novel binding mechanism.展开更多
There is increasing evidence of estrogenic activities of source waters and drinking waters in China based on estrogen receptors(ERs) testing.However,relating such activities to retinoid X receptors(RXRs) in both drink...There is increasing evidence of estrogenic activities of source waters and drinking waters in China based on estrogen receptors(ERs) testing.However,relating such activities to retinoid X receptors(RXRs) in both drinking and source waters are lacking.To rectify this situation,we assessed 23 source water samples from six major river systems in China.We also collected samples at various stages of water processing from three drinking water treatment plants(DWTPs) using a two-hybrid RXR yeast assay with and without metabolism.No RXR agonistic activity was observed,but significant antagonistic activity was detected in all sample extracts.The RXR antagonistic activities of source water sample extracts ranged from 15.2% to 57.8% without metabolism and 11.5% to 68.3% with metabolism,respectively.In the drinking water treatment processes,RXR antagonistic activities without metabolism and with metabolism of up to 31.4% and 37.5% were removed,respectively.Nevertheless,the remaining RXR antagonists in treated drinking water from these source waters could still be harmful to human health.To the best of our knowledge,the occurrence of in vitro RXR disruption activities in source and drinking water has not been previously reported in China.Therefore,an attempt was made to conduct detailed studies investigating RXR disrupting activities and their possible risks in source and drinking water.展开更多
目的:观察阿托伐他汀(Atorv)对链脲佐菌素(STZ)诱导的糖尿病高脂喂养载脂蛋白E敲除(apolipoprotein E knockout,ApoE-/-)小鼠动脉粥样硬化的影响,探讨阿托伐他汀在糖尿病合并高脂饮食条件下对抗动脉粥样硬化的机制。方法:C57小鼠8只作...目的:观察阿托伐他汀(Atorv)对链脲佐菌素(STZ)诱导的糖尿病高脂喂养载脂蛋白E敲除(apolipoprotein E knockout,ApoE-/-)小鼠动脉粥样硬化的影响,探讨阿托伐他汀在糖尿病合并高脂饮食条件下对抗动脉粥样硬化的机制。方法:C57小鼠8只作为对照,34只高脂喂养的ApoE-/-小鼠随机分为3组:ApoE-/-组、STZ-ApoE-/-组和STZ-ApoE-/-+Atorv组。STZ腹腔注射建立糖尿病动物模型,测定小鼠空腹血糖、血脂水平,HE染色图像分析测定胸主动脉斑块面积;免疫杂交检测主动脉及细胞内NADPH氧化酶亚基gp91phox蛋白水平;Fenton反应Griess显色法测定血清及胸主动脉匀浆上清液活性氧(ROS)水平。I型胶原酶消化法培养人脐静脉内皮细胞(HUVECs),流式细胞术检测内皮细胞内ROS的水平,光泽精分析法测定NADPH氧化酶活性。采用干扰RNA和质粒转染的方法评价类视黄醇X受体α(RXRα)在Atorv抑制氧化应激中的作用。结果:(1)与C57组相比,ApoE-/-组小鼠胸主动脉斑块面积显著增加[(215.88±34.19)μm2vs 0μm2,P<0.01],2组间空腹血糖水平无显著差异,血清甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、血清及胸主动脉ROS、胸主动脉gp91phox表达水平显著缩小(P<0.05);(2)与ApoE-/-组相比,STZ-ApoE-/-组胸主动脉斑块面积进一步增加[(314.13±35.72)μm2vs(215.88±34.19)μm2,P<0.05],血糖水平升高,血清TC、LDL-C、血清及胸主动脉ROS、胸主动脉gp91phox水平进一步增加(P<0.05);(3)与STZ-ApoE-/-组相比,STZ-ApoE-/-+Atorv组胸主动脉粥样斑块面积显著降低[(217.47±24.56)μm2vs(314.13±35.72)μm2,P<0.05],血糖、血清TG、HDL、TC、和LDL-C无显著变化,血清及胸主动脉ROS、胸主动脉gp91phox水平亦显著降低(P<0.05);(4)高糖(25 mmol/L)干预后,HUVECs内ROS含量、gp91phox蛋白水平及NADPH氧化酶活性明显增加(P<0.05),阿托伐他汀(10-8~10-6mol/L)显著降低高糖环境下HUVECs胞内ROS含量、gp91phox表达及NADPH氧化酶活性,且具有浓度依赖性;(5)将RXRαsiRNA转染至HUVECs之后,阿托伐他汀(10-6mol/L)对高糖环境下ROS生成及NADPH氧化酶活性的抑制效应显著减弱,RXRα质粒转染使RXRα过表达后,阿托伐他汀(10-6mol/L)抑制ROS生成及NADPH氧化酶活性的作用明显增强(P<0.05)。结论:阿托伐他汀通过抑制高糖环境下机体的氧化应激反应对抗动脉粥样硬化;核受体RXRα介导阿托伐他汀的抗氧化应激效应。展开更多
大黄素(emodin)对多种肿瘤细胞有较强的抑制增殖和诱导凋亡的作用,但其作用机制尚不清楚。本研究通过配体-受体竞争结合实验以及报告基因检测了大黄素对维甲酸X受体(retinoid X receptor alpha,RXRα)的结合和转录活性的调控,并研究了...大黄素(emodin)对多种肿瘤细胞有较强的抑制增殖和诱导凋亡的作用,但其作用机制尚不清楚。本研究通过配体-受体竞争结合实验以及报告基因检测了大黄素对维甲酸X受体(retinoid X receptor alpha,RXRα)的结合和转录活性的调控,并研究了大黄素对肺癌细胞H460和肝癌细胞SMMC-7721生长和凋亡的作用。结果发现,大黄素对两种癌细胞有很强的抑制增殖作用,加入RXRα的天然配体9-顺式视黄酸(9-cis-retinoid acid,9-cis-RA)共同处理可显著缓解这种抑制作用。大黄素能浓度依赖地引起两种癌细胞系的凋亡,使细胞核出现碎裂和染色质浓染。报告基因实验发现大黄素对RXRα同源和异源二聚体的转录激活有显著抑制作用。体外的配体竞争结合实验发现,大黄素不直接结合RXRα的配体结合区。蛋白质免疫印迹实验发现,大黄素不影响RXRα的蛋白表达。结果提示,大黄素具有诱导肺癌细胞H460和肝癌细胞SMMC-7721凋亡和抑制细胞生长的作用,大黄素抑制9-cis-RA对RXR转录激活作用以及9-cis-RA具有一定程度拮抗大黄素对肺癌细胞H460和肝癌细胞SMMC-7721的生长抑制作用,提示大黄素的抗癌作用可能与细胞内RXR的功能有关,并以RXR转录非依赖性的方式起作用。配体竞争结合实验结果提示大黄素可能间接作用于RXR。展开更多
基金supported by grants from the National Natural Science Foundation of China(81270282,81070176,30600242,81170192,81200163)Wenzhou Science Technology Bureau Foundation(Y20100010)Education Foundation of Zhejiang Province(Y200906376)
文摘BACKGROUND: Retinoid X receptor(RXR) plays a central role in the regulation of intracellular receptor signaling pathways. The activation of RXR has protective effect on H2O2-induced apoptosis of H9c2 ventricular cells in rats. But the protective effect and mechanism of activating RXR in cardiomyocytes against hypoxia/reoxygenation(H/R)-induced oxidative iniury are still unclear.METHODS: The model of H/R injury was established through hypoxia for 2 hours and reoxygenation for 4 hours in H9c2 cardiomyocytes of rats. 9-cis-retinoic acid(9-cis RA) was obtained as an RXR agonist, and HX531 as an RXR antagonist. Cultured cardiomyocytes were randomly divided into four groups: sham group, H/R group, H/R+9-cis RA-pretreated group(100 nmol/L 9-cis RA), and H/R+9-cis RA+HX531-pretreated group(2.5 μmol/L HX531). The cell viability was measured by MTT, apoptosis rate of cardiomyocytes by flow cytometry analysis, and mitochondrial membrane potential(ΔΨm) by JC-1 fluorescent probe, and protein expressions of Bcl-2, Bax and cleaved caspase-9 with Western blotting. All measurement data were expressed as mean±standard deviation, and analyzed using one-way ANOVA and the Dunnett test. Differences were considered signif icant when P was <0.05.RESULTS: Pretreatment with RXR agonist enhanced cell viability, reduced apoptosis ratio, and stabled ΔΨm. Dot blotting experiments showed that under H/R stress conditions, Bcl-2 protein level decreased, while Bax and cleaved caspase-9 were increased. 9-cis RA administration before H/R stress prevented these effects, but the protective effects of activating RXR on cardiomyocytes against H/R induced oxidative injury were abolished when pretreated with RXR pan-antagonist HX531.CONCLUSION: The activation of RXR has protective effects against H/R injury in H9c2 cardiomyocytes of rats through attenuating signaling pathway of mitochondria apoptosis.
基金supported by Natural Sciences and Engineering Council of Canada Discovery Grant to RLC and GES
文摘Some adult vertebrate species,such as newts,axolotls and zebrafish,have the ability to regenerate their central nervous system（CNS）.However,the factors that establish a permissive CNS environment for correct morphological and functional regeneration in these species are not well understood.Recent evidence supports a role for retinoid signaling in the intrinsic ability of neurons,in these regeneration-competent species,to regrow after CNS injury.Previously,we demonstrated that a specific retinoic acid receptor（RAR）subtype,RARβ,mediates the effects of endogenous retinoic acid（RA）on neuronal growth and guidance in the adult newt CNS after injury.Here,we now examine the expression of the retinoid X receptor RXRα（a potential heterodimeric transcriptional regulator with RARβ）,in newt tail and spinal cord regeneration.We show that at 21 days post-amputation（dpa）,RXRαis expressed at temporally distinct periods and in non-overlapping spatial domains compared to RARβ.Whereas RARβprotein levels increase,RXRαproteins level decrease by 21 dpa.A selective agonist for RXR,SR11237,prevents both this downregulation of RXRαand upregulation of RARβand inhibits tail and caudal spinal cord regeneration.Moreover,treatment with a selective antagonist for RARβ,LE135,inhibits regeneration with the same morphological consequences as treatment with SR11237.Interestingly,LE135 treatment also inhibits the normal downregulation of RXRαin tail and spinal cord tissues at 21 dpa.These results reveal a previously unidentified,indirect regulatory feedback loop between these two receptor subtypes in regulating the regeneration of tail and spinal cord tissues in this regeneration-competent newt.
文摘All-trans retinoic acid (ATRA) triggers a wide range of effects on vertebrate development by regulating cell proliferation, differentiation, and apoptosis. ATRA activates retinoic acid receptors (RARs) which heterodimerize with retinoid X receptors (RXRs). RAR/RXR heterodimers function as ATRA-dependent transcriptional regulators by binding to retinoic acid response elements (RAREs). To identify RAR/RXR heterodimer-binding sites in the human genome, we performed a modified yeast one-hybrid assays and identified 193 RAR/RXR heterodimer-binding fragments in the human genome. The putative target genes included genes involved in development process and cell differentiation. Gel mobility shift assays indicated that 160 putative RAREs could directly interact with the RAR/RXR heterodimer. Moreover, 19 functional regulatory single nucleotide polymorphisms (rSNPs) on the RAR/RXR-binding sequences were identified by analyzing the difference in the DNA-binding affinities. These results provide insights into the molecular mechanisms underlying the physiological and pathological actions of RAR/RXR heterodimers.
基金supported by the National Natural Science Foundation of China (No. 22177143)the COMRA program (No. DY135-B2–08)。
文摘A novel meroterpenoid,named meroterpenthiazole A(1),was isolated from the deep-sea-derived Penicillium allii-sativi.Its structure was established by extensive spectroscopic and computational methods.Meroterpenthiazole A bears a rare benzothiazole moiety in nature.Compound 1 significantly inhibited retinoid X receptor(RXR)-α transcriptional effect(K_(D)=12.3 μmol/L) through a novel binding mechanism.
基金supported by the Environmental Protection National Commonweal Research Project (200909040)International Scientific and Technological Cooperation Projects by the Ministry of Science and Technology of China (2009DFA91920)
文摘There is increasing evidence of estrogenic activities of source waters and drinking waters in China based on estrogen receptors(ERs) testing.However,relating such activities to retinoid X receptors(RXRs) in both drinking and source waters are lacking.To rectify this situation,we assessed 23 source water samples from six major river systems in China.We also collected samples at various stages of water processing from three drinking water treatment plants(DWTPs) using a two-hybrid RXR yeast assay with and without metabolism.No RXR agonistic activity was observed,but significant antagonistic activity was detected in all sample extracts.The RXR antagonistic activities of source water sample extracts ranged from 15.2% to 57.8% without metabolism and 11.5% to 68.3% with metabolism,respectively.In the drinking water treatment processes,RXR antagonistic activities without metabolism and with metabolism of up to 31.4% and 37.5% were removed,respectively.Nevertheless,the remaining RXR antagonists in treated drinking water from these source waters could still be harmful to human health.To the best of our knowledge,the occurrence of in vitro RXR disruption activities in source and drinking water has not been previously reported in China.Therefore,an attempt was made to conduct detailed studies investigating RXR disrupting activities and their possible risks in source and drinking water.
文摘目的:观察阿托伐他汀(Atorv)对链脲佐菌素(STZ)诱导的糖尿病高脂喂养载脂蛋白E敲除(apolipoprotein E knockout,ApoE-/-)小鼠动脉粥样硬化的影响,探讨阿托伐他汀在糖尿病合并高脂饮食条件下对抗动脉粥样硬化的机制。方法:C57小鼠8只作为对照,34只高脂喂养的ApoE-/-小鼠随机分为3组:ApoE-/-组、STZ-ApoE-/-组和STZ-ApoE-/-+Atorv组。STZ腹腔注射建立糖尿病动物模型,测定小鼠空腹血糖、血脂水平,HE染色图像分析测定胸主动脉斑块面积;免疫杂交检测主动脉及细胞内NADPH氧化酶亚基gp91phox蛋白水平;Fenton反应Griess显色法测定血清及胸主动脉匀浆上清液活性氧(ROS)水平。I型胶原酶消化法培养人脐静脉内皮细胞(HUVECs),流式细胞术检测内皮细胞内ROS的水平,光泽精分析法测定NADPH氧化酶活性。采用干扰RNA和质粒转染的方法评价类视黄醇X受体α(RXRα)在Atorv抑制氧化应激中的作用。结果:(1)与C57组相比,ApoE-/-组小鼠胸主动脉斑块面积显著增加[(215.88±34.19)μm2vs 0μm2,P<0.01],2组间空腹血糖水平无显著差异,血清甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、血清及胸主动脉ROS、胸主动脉gp91phox表达水平显著缩小(P<0.05);(2)与ApoE-/-组相比,STZ-ApoE-/-组胸主动脉斑块面积进一步增加[(314.13±35.72)μm2vs(215.88±34.19)μm2,P<0.05],血糖水平升高,血清TC、LDL-C、血清及胸主动脉ROS、胸主动脉gp91phox水平进一步增加(P<0.05);(3)与STZ-ApoE-/-组相比,STZ-ApoE-/-+Atorv组胸主动脉粥样斑块面积显著降低[(217.47±24.56)μm2vs(314.13±35.72)μm2,P<0.05],血糖、血清TG、HDL、TC、和LDL-C无显著变化,血清及胸主动脉ROS、胸主动脉gp91phox水平亦显著降低(P<0.05);(4)高糖(25 mmol/L)干预后,HUVECs内ROS含量、gp91phox蛋白水平及NADPH氧化酶活性明显增加(P<0.05),阿托伐他汀(10-8~10-6mol/L)显著降低高糖环境下HUVECs胞内ROS含量、gp91phox表达及NADPH氧化酶活性,且具有浓度依赖性;(5)将RXRαsiRNA转染至HUVECs之后,阿托伐他汀(10-6mol/L)对高糖环境下ROS生成及NADPH氧化酶活性的抑制效应显著减弱,RXRα质粒转染使RXRα过表达后,阿托伐他汀(10-6mol/L)抑制ROS生成及NADPH氧化酶活性的作用明显增强(P<0.05)。结论:阿托伐他汀通过抑制高糖环境下机体的氧化应激反应对抗动脉粥样硬化;核受体RXRα介导阿托伐他汀的抗氧化应激效应。
文摘大黄素(emodin)对多种肿瘤细胞有较强的抑制增殖和诱导凋亡的作用,但其作用机制尚不清楚。本研究通过配体-受体竞争结合实验以及报告基因检测了大黄素对维甲酸X受体(retinoid X receptor alpha,RXRα)的结合和转录活性的调控,并研究了大黄素对肺癌细胞H460和肝癌细胞SMMC-7721生长和凋亡的作用。结果发现,大黄素对两种癌细胞有很强的抑制增殖作用,加入RXRα的天然配体9-顺式视黄酸(9-cis-retinoid acid,9-cis-RA)共同处理可显著缓解这种抑制作用。大黄素能浓度依赖地引起两种癌细胞系的凋亡,使细胞核出现碎裂和染色质浓染。报告基因实验发现大黄素对RXRα同源和异源二聚体的转录激活有显著抑制作用。体外的配体竞争结合实验发现,大黄素不直接结合RXRα的配体结合区。蛋白质免疫印迹实验发现,大黄素不影响RXRα的蛋白表达。结果提示,大黄素具有诱导肺癌细胞H460和肝癌细胞SMMC-7721凋亡和抑制细胞生长的作用,大黄素抑制9-cis-RA对RXR转录激活作用以及9-cis-RA具有一定程度拮抗大黄素对肺癌细胞H460和肝癌细胞SMMC-7721的生长抑制作用,提示大黄素的抗癌作用可能与细胞内RXR的功能有关,并以RXR转录非依赖性的方式起作用。配体竞争结合实验结果提示大黄素可能间接作用于RXR。
