Background： Sequence-specific binding by transcription factors （TFs） plays a significant role in the selection and regulation of target genes. At the protein：DNA interface, amino acid side-chains construct a diver...Background： Sequence-specific binding by transcription factors （TFs） plays a significant role in the selection and regulation of target genes. At the protein：DNA interface, amino acid side-chains construct a diverse physicochemical network of specific and non-specific interactions, and seemingly subtle changes in amino acid identity at certain positions may dramatically impact TF：DNA binding. Variation of these specificity-determining residues （SDRs） is a major mechanism of functional divergence between TFs with strong structural or sequence homology. Methods： In this study, we employed a combination of high-throughput specificity profiling by SELEX and Spec-seq, structural modeling, and evolutionary analysis to probe the binding preferences of winged helix-turn-helix TFs belonging to the OmpR sub-family in Escherichia coil Results： We found that E. coli OmpR paralogs recognize tandem, variably spaced repeats composed of＂GT-A＂ or ＂GCT＂-containing half-sites. Some divergent sequence preferences observed within the ＂GT-A＂ mode correlate with amino acid similarity; conversely, ＂GCT＂-based motifs were observed for a subset of paralogs with low sequence homology. Direct specificity profiling of a subset of OmpR homologues （CpxR, RstA, and OmpR） as well as predicted ＂SDR-swap＂ variants revealed that individual SDRs may impact sequence preferences locally through direct contact with DNA bases or distally via the DNA backbone. Conclusions： Overall, our work provides evidence for a common structural code for sequence-specific wHTH：DNA interactions, and demonstrates that surprisingly modest residue changes can enable recognition of highly divergent sequence motifs. Further examination of SDR predictions will likely reveal additional mechanisms controlling the evolutionary divergence of this important class of transcriptional regulators.展开更多
目的:探讨T辅助细胞亚群Th1/Th2和Treg在非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)发病机制中的意义.方法:SD大鼠正常喂养1wk后,随机分为正常组(n=20)和高脂饮食组(n=20).正常组大鼠以普通饲料喂养,高脂饮食组以高...目的:探讨T辅助细胞亚群Th1/Th2和Treg在非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)发病机制中的意义.方法:SD大鼠正常喂养1wk后,随机分为正常组(n=20)和高脂饮食组(n=20).正常组大鼠以普通饲料喂养,高脂饮食组以高脂饲料喂养.实验第8、16周分批处死大鼠.观察肝组织的病理改变,荧光定量PCR方法检测肝脏TNF-a、IFN-γ、IL-4和Foxp3的基因表达.结果:高脂饮食8wk大鼠肝细胞脂肪变明显,无明显炎症改变,IFN-γ、IL-4在肝脏的基因表达与正常组比较无明显变化,TNF-α稍升高,但无统计学意义,Foxp3 mRNA的表达比正常组明显降低(ct值:26.12±0.69 vs 24.22±0.62,P<0.05).高脂饮食16wk大鼠脂肪肝明显,炎症明显,IFN-γ和TNF-α基因表达均显著升高(ct值:24.52±0.87 vs 29.94±1.44,24.31±1.13 vs 28.88±1.95,均P<0.05),IL-4与正常组相比较无明显变化,Foxp3基因表达较正常组和高脂饮食8wk时均显著降低(ct值:32.57±1.54 vs 24.29±1.08,26.12±0.69,P<0.05).结论:高脂饮食大鼠肝脏Foxp3和Treg表达减少可能是高脂饮食NAFLD发生发展的重要因素.IFN-γ和TNF-α的联合作用加重了肝脏的炎症损伤.展开更多
目的:探讨慢性乙型肝炎患者外周血CD4+CD25+T调节细胞(regulatory T cell,Treg)的变化及其意义.方法:采用流式细胞术对66例乙肝病毒(hepatitis B virus,HBV)感染者和19例健康对照者外周血CD4+CD25+Treg细胞进行检测,并观察CD4+CD25+Tre...目的:探讨慢性乙型肝炎患者外周血CD4+CD25+T调节细胞(regulatory T cell,Treg)的变化及其意义.方法:采用流式细胞术对66例乙肝病毒(hepatitis B virus,HBV)感染者和19例健康对照者外周血CD4+CD25+Treg细胞进行检测,并观察CD4+CD25+Treg细胞与患者总胆红素(total bilirubin,TBIL)、凝血酶原活动度(prothrombin activitv,PTA)和病毒复制指标HBV DNA水平的关系.免疫组化检测叉状头/翅膀状螺旋转录因子(forkhead/winged helix transcription factor,FOXP3)蛋白的表达水平.结果:慢性重型肝炎组CD4+CD25+Treg细胞(4.80±1.50)%分别高于慢性肝炎组(1.67±0.87)%、HBV携带者组(0.53±0.37)%和正常对照组(0.50±0.34)%,(P<0.01);慢性肝炎组与HBV携带者组和正常对照组相比有显著性差异(P<0.01);慢性重型乙型肝炎患者和慢性乙型肝炎患者FOXP3蛋白表达也相应增高,且与CD4+CD25+Treg细胞的变化相平行.CD4+CD25+Treg细胞的变化与TBIL的变化成正相关(r=0.43,P<0.01),与PTA的变化成负相关(r=-0.57,P<0.05),与HBV-DNA水平的变化没有相关性(r=0.22,P>0.05).结论:在慢性乙型肝炎发病过程中,CD4+CD25+Treg细胞水平相应增高,FOXP3蛋白变化与CD4+CD25+Treg细胞的改变相平行.展开更多
目的观察白斑颗粒Ⅰ号方对白癜风患者Foxp3 m RNA表达的影响,阐明白斑Ⅰ号方治疗白癜风的作用机制。方法白癜风患者60例,随机分为试验组和对照组各30例,健康对照组30例,采用RT-PCR方法检测各组PBMC中Foxp3 m RNA表达变化情况。结果白癜...目的观察白斑颗粒Ⅰ号方对白癜风患者Foxp3 m RNA表达的影响,阐明白斑Ⅰ号方治疗白癜风的作用机制。方法白癜风患者60例,随机分为试验组和对照组各30例,健康对照组30例,采用RT-PCR方法检测各组PBMC中Foxp3 m RNA表达变化情况。结果白癜风患者组Foxp3 m RNA水平低于健康对照组,差异有统计学意义(P<0.05);实验组治疗3个月后Foxp3 m RNA水平高于治疗前,差异有统计学意义(P<0.05);对照组治疗3个月后Foxp3 m RNA水平高于治疗前,差异有统计学意义(P<0.05);治疗3个月后,实验组治疗前后外周血Foxp3 m RNA升高值高于对照组治疗前后外周血Foxp3 m RNA升高值,差异有统计学意义(P<0.05)。结论白斑颗粒Ⅰ号可能通过上调调节T细胞功能,使PBMC Foxp3 m RNA恢复或接近正常水平达到治疗白癜风的目的。展开更多
文摘Background： Sequence-specific binding by transcription factors （TFs） plays a significant role in the selection and regulation of target genes. At the protein：DNA interface, amino acid side-chains construct a diverse physicochemical network of specific and non-specific interactions, and seemingly subtle changes in amino acid identity at certain positions may dramatically impact TF：DNA binding. Variation of these specificity-determining residues （SDRs） is a major mechanism of functional divergence between TFs with strong structural or sequence homology. Methods： In this study, we employed a combination of high-throughput specificity profiling by SELEX and Spec-seq, structural modeling, and evolutionary analysis to probe the binding preferences of winged helix-turn-helix TFs belonging to the OmpR sub-family in Escherichia coil Results： We found that E. coli OmpR paralogs recognize tandem, variably spaced repeats composed of＂GT-A＂ or ＂GCT＂-containing half-sites. Some divergent sequence preferences observed within the ＂GT-A＂ mode correlate with amino acid similarity; conversely, ＂GCT＂-based motifs were observed for a subset of paralogs with low sequence homology. Direct specificity profiling of a subset of OmpR homologues （CpxR, RstA, and OmpR） as well as predicted ＂SDR-swap＂ variants revealed that individual SDRs may impact sequence preferences locally through direct contact with DNA bases or distally via the DNA backbone. Conclusions： Overall, our work provides evidence for a common structural code for sequence-specific wHTH：DNA interactions, and demonstrates that surprisingly modest residue changes can enable recognition of highly divergent sequence motifs. Further examination of SDR predictions will likely reveal additional mechanisms controlling the evolutionary divergence of this important class of transcriptional regulators.
文摘目的:探讨T辅助细胞亚群Th1/Th2和Treg在非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)发病机制中的意义.方法:SD大鼠正常喂养1wk后,随机分为正常组(n=20)和高脂饮食组(n=20).正常组大鼠以普通饲料喂养,高脂饮食组以高脂饲料喂养.实验第8、16周分批处死大鼠.观察肝组织的病理改变,荧光定量PCR方法检测肝脏TNF-a、IFN-γ、IL-4和Foxp3的基因表达.结果:高脂饮食8wk大鼠肝细胞脂肪变明显,无明显炎症改变,IFN-γ、IL-4在肝脏的基因表达与正常组比较无明显变化,TNF-α稍升高,但无统计学意义,Foxp3 mRNA的表达比正常组明显降低(ct值:26.12±0.69 vs 24.22±0.62,P<0.05).高脂饮食16wk大鼠脂肪肝明显,炎症明显,IFN-γ和TNF-α基因表达均显著升高(ct值:24.52±0.87 vs 29.94±1.44,24.31±1.13 vs 28.88±1.95,均P<0.05),IL-4与正常组相比较无明显变化,Foxp3基因表达较正常组和高脂饮食8wk时均显著降低(ct值:32.57±1.54 vs 24.29±1.08,26.12±0.69,P<0.05).结论:高脂饮食大鼠肝脏Foxp3和Treg表达减少可能是高脂饮食NAFLD发生发展的重要因素.IFN-γ和TNF-α的联合作用加重了肝脏的炎症损伤.
文摘目的观察白斑颗粒Ⅰ号方对白癜风患者Foxp3 m RNA表达的影响,阐明白斑Ⅰ号方治疗白癜风的作用机制。方法白癜风患者60例,随机分为试验组和对照组各30例,健康对照组30例,采用RT-PCR方法检测各组PBMC中Foxp3 m RNA表达变化情况。结果白癜风患者组Foxp3 m RNA水平低于健康对照组,差异有统计学意义(P<0.05);实验组治疗3个月后Foxp3 m RNA水平高于治疗前,差异有统计学意义(P<0.05);对照组治疗3个月后Foxp3 m RNA水平高于治疗前,差异有统计学意义(P<0.05);治疗3个月后,实验组治疗前后外周血Foxp3 m RNA升高值高于对照组治疗前后外周血Foxp3 m RNA升高值,差异有统计学意义(P<0.05)。结论白斑颗粒Ⅰ号可能通过上调调节T细胞功能,使PBMC Foxp3 m RNA恢复或接近正常水平达到治疗白癜风的目的。
文摘目的从免疫逃逸角度探讨“扶正祛瘀”中药理冲汤对异种移植子宫肌瘤小鼠吲哚胺-2,3双加氧酶(IDO和叉头状螺旋转录因子3(Foxp3)表达的影响。方法采用完全随机分组法将32只CB-17 Scid雌性小鼠分为正常组、模型组、理冲汤组和阳性药组,每组8只。采用异种移植法制备子宫肌瘤动物模型;造模成功后,理冲汤组给予理冲汤,阳性药组给予米非司酮,正常组和模型组给予等量生理盐水,连续干预4周后进行组织样本采集。通过HE染色观察各组小鼠子宫平滑肌组织病理学改变;采用免疫印迹法检测各组小鼠子宫平滑肌组织中IDO表达含量;采用实时荧光定量PCR检测Foxp3 m RNA的表达含量。结果与模型组比较,理冲汤组小鼠子宫内膜及肌层增厚现象减轻,纤维组织含量较少;理冲汤组小鼠子宫平滑肌组织中IDO、Foxp3 mRNA表达含量较模型组明显降低(P<0.05或P<0.01)。结论理冲汤具有抑制子宫肌瘤发生发展的作用,其药理机制可能与阻断肿瘤免疫逃逸途径相关。
