The P22 phage system is an intensely studied model system. Studies have ranged from biochemical analysis of basic life processes to the use of this phage for phage therapy. The phage tailspike protein (TSP) has itself...The P22 phage system is an intensely studied model system. Studies have ranged from biochemical analysis of basic life processes to the use of this phage for phage therapy. The phage tailspike protein (TSP) has itself been the subject of intensive studies over the past fifty years. The P22 TSP is essential for initiation of the infection process and instrumental as the last protein assembled onto the phage particle structure to complete its assembly. It has also been the subject for many structural studies including cryoelectron microscopic analysis and photophysical studies. It has been a model for in vivo and in vitro protein folding including analysis using P22 TSP temperature-sensitive for folding mutations (tsf). Recently the structure and function of the N-terminal domain (NTD), including some aspects of the structural stability of the P22 TSP NTD (aa1-aa108), are being genetically dissected. This report strongly supports the notion that two amino acids, not localized to the internal NTD dome stem, are important in the structural stability of the P22 TSP NTD.展开更多
Hepadnaviruses, including human hepatitis B virus （HBV）, replicate through reverse transcription of an RNA intermediate, the pregenomic RNA （pgRNA）. Despite this kinship to retroviruses, there are fundamental diff...Hepadnaviruses, including human hepatitis B virus （HBV）, replicate through reverse transcription of an RNA intermediate, the pregenomic RNA （pgRNA）. Despite this kinship to retroviruses, there are fundamental differences beyond the fact that hepadnavirions contain DNA instead of RNA. Most peculiar is the initiation of reverse transcription： it occurs by protein-priming, is strictly committed to using an RNA hairpin on the pgRNA, ε, as template, and depends on cellular chaperones; moreover, proper replication can apparently occur only in the specialized environment of intact nucleocapsids. This complexity has hampered an in-depth mechanistic understanding. The recent successful reconstitution in the test tube of active replication initiation complexes from purified components, for duck HBV （DHBV）, now allows for the analysis of the biochemistry of hepadnaviral replication at the molecular level. Here we review the current state of knowledge at all steps of the hepadnaviral genome replication cycle, with emphasis on new insights that turned up by the use of such cellfree systems. At this time, they can, unfortunately, not be complemented by three-dimensional structural information on the involved components. However, at least for the ~ RNA element such information is emerging, raising expectations that combining biophysics with biochemistry and genetics will soon provide a powerful integrated approach for solving the many outstanding questions. The ultimate, though most challenging goal, will be to visualize the hepadnaviral reverse transcriptase in the act of synthesizing DNA, which will also have strong implications for drug development.展开更多
After spinal cord injury, dysregulated miRNAs appear and can participate in inflammatory responses, as well as the inhibition of apoptosis and axon regeneration through multiple pathways. However, the functions of miR...After spinal cord injury, dysregulated miRNAs appear and can participate in inflammatory responses, as well as the inhibition of apoptosis and axon regeneration through multiple pathways. However, the functions of miRNAs in spinal cord ischemia-reperfusion injury progression remain unclear. miRCURY LNATM Arrays were used to analyze miRNA expression profiles of rats after 90 minutes of ischemia followed by reperfusion for 24 and 48 hours. Furthermore, subsequent construction of aberrantly expressed miRNA regulatory patterns involved cell survival, proliferation, and apoptosis. Remarkably, the mitogen-activated protein kinase(MAPK) signaling pathway was the most significantly enriched pathway among 24-and 48-hour groups. Bioinformatics analysis and quantitative reverse transcription polymerase chain reaction confirmed the persistent overexpression of miR-22-3 p in both groups. These results suggest that the aberrant miRNA regulatory network is possibly regulated MAPK signaling and continuously affects the physiological and biochemical status of cells, thus participating in the regulation of spinal cord ischemia-reperfusion injury. As such, miR-22-3 p may play sustained regulatory roles in spinal cord ischemia-reperfusion injury. All experimental procedures were approved by the Animal Ethics Committee of Jilin University, China [approval No. 2020(Research) 01].展开更多
目前,临床上治疗乙型肝炎病毒(Hepatitis B virus,HBV)导致的慢性乙肝药物存在应答率低、副作用大和耐药性等缺点,急需寻找抗病毒治疗的新靶点。HBV反转录过程中,反转录酶(P蛋白)和位于病毒前基因组RNA(Pregenome RNA,pgRNA)5′邻近的RN...目前,临床上治疗乙型肝炎病毒(Hepatitis B virus,HBV)导致的慢性乙肝药物存在应答率低、副作用大和耐药性等缺点,急需寻找抗病毒治疗的新靶点。HBV反转录过程中,反转录酶(P蛋白)和位于病毒前基因组RNA(Pregenome RNA,pgRNA)5′邻近的RNA包装信号(ε)的相互作用(又称P-ε相互作用)非常关键,该相互作用有宿主蛋白如热激蛋白的参与。P-ε复合物形成后,一方面引发反转录的启动,另一方面启动核衣壳的包装。目前封闭P-ε相互作用的策略主要有热激蛋白抑制剂、ε适配子和阻断P蛋白的化合物三个方面,其机制为针对性靶向P蛋白或者宿主蛋白,从而直接或间接地阻断P-ε相互作用。前期,我们首次体外筛选到干扰P-ε相互作用的适配子,体外实验及动物实验均证实,该类适配子强烈抑制HBV复制。总之,P-ε相互作用为抗乙肝研究的临床治疗提供了一个极具吸引力和应用前景的药物靶点,上述三种策略绕过或克服了目前临床上HBV对化疗药的耐药问题,具有较高的应用前景。展开更多
文摘The P22 phage system is an intensely studied model system. Studies have ranged from biochemical analysis of basic life processes to the use of this phage for phage therapy. The phage tailspike protein (TSP) has itself been the subject of intensive studies over the past fifty years. The P22 TSP is essential for initiation of the infection process and instrumental as the last protein assembled onto the phage particle structure to complete its assembly. It has also been the subject for many structural studies including cryoelectron microscopic analysis and photophysical studies. It has been a model for in vivo and in vitro protein folding including analysis using P22 TSP temperature-sensitive for folding mutations (tsf). Recently the structure and function of the N-terminal domain (NTD), including some aspects of the structural stability of the P22 TSP NTD (aa1-aa108), are being genetically dissected. This report strongly supports the notion that two amino acids, not localized to the internal NTD dome stem, are important in the structural stability of the P22 TSP NTD.
文摘Hepadnaviruses, including human hepatitis B virus （HBV）, replicate through reverse transcription of an RNA intermediate, the pregenomic RNA （pgRNA）. Despite this kinship to retroviruses, there are fundamental differences beyond the fact that hepadnavirions contain DNA instead of RNA. Most peculiar is the initiation of reverse transcription： it occurs by protein-priming, is strictly committed to using an RNA hairpin on the pgRNA, ε, as template, and depends on cellular chaperones; moreover, proper replication can apparently occur only in the specialized environment of intact nucleocapsids. This complexity has hampered an in-depth mechanistic understanding. The recent successful reconstitution in the test tube of active replication initiation complexes from purified components, for duck HBV （DHBV）, now allows for the analysis of the biochemistry of hepadnaviral replication at the molecular level. Here we review the current state of knowledge at all steps of the hepadnaviral genome replication cycle, with emphasis on new insights that turned up by the use of such cellfree systems. At this time, they can, unfortunately, not be complemented by three-dimensional structural information on the involved components. However, at least for the ~ RNA element such information is emerging, raising expectations that combining biophysics with biochemistry and genetics will soon provide a powerful integrated approach for solving the many outstanding questions. The ultimate, though most challenging goal, will be to visualize the hepadnaviral reverse transcriptase in the act of synthesizing DNA, which will also have strong implications for drug development.
基金supported by the National Natural Science Foundation of China,No.81350013(to XYY)。
文摘After spinal cord injury, dysregulated miRNAs appear and can participate in inflammatory responses, as well as the inhibition of apoptosis and axon regeneration through multiple pathways. However, the functions of miRNAs in spinal cord ischemia-reperfusion injury progression remain unclear. miRCURY LNATM Arrays were used to analyze miRNA expression profiles of rats after 90 minutes of ischemia followed by reperfusion for 24 and 48 hours. Furthermore, subsequent construction of aberrantly expressed miRNA regulatory patterns involved cell survival, proliferation, and apoptosis. Remarkably, the mitogen-activated protein kinase(MAPK) signaling pathway was the most significantly enriched pathway among 24-and 48-hour groups. Bioinformatics analysis and quantitative reverse transcription polymerase chain reaction confirmed the persistent overexpression of miR-22-3 p in both groups. These results suggest that the aberrant miRNA regulatory network is possibly regulated MAPK signaling and continuously affects the physiological and biochemical status of cells, thus participating in the regulation of spinal cord ischemia-reperfusion injury. As such, miR-22-3 p may play sustained regulatory roles in spinal cord ischemia-reperfusion injury. All experimental procedures were approved by the Animal Ethics Committee of Jilin University, China [approval No. 2020(Research) 01].
文摘目前,临床上治疗乙型肝炎病毒(Hepatitis B virus,HBV)导致的慢性乙肝药物存在应答率低、副作用大和耐药性等缺点,急需寻找抗病毒治疗的新靶点。HBV反转录过程中,反转录酶(P蛋白)和位于病毒前基因组RNA(Pregenome RNA,pgRNA)5′邻近的RNA包装信号(ε)的相互作用(又称P-ε相互作用)非常关键,该相互作用有宿主蛋白如热激蛋白的参与。P-ε复合物形成后,一方面引发反转录的启动,另一方面启动核衣壳的包装。目前封闭P-ε相互作用的策略主要有热激蛋白抑制剂、ε适配子和阻断P蛋白的化合物三个方面,其机制为针对性靶向P蛋白或者宿主蛋白,从而直接或间接地阻断P-ε相互作用。前期,我们首次体外筛选到干扰P-ε相互作用的适配子,体外实验及动物实验均证实,该类适配子强烈抑制HBV复制。总之,P-ε相互作用为抗乙肝研究的临床治疗提供了一个极具吸引力和应用前景的药物靶点,上述三种策略绕过或克服了目前临床上HBV对化疗药的耐药问题,具有较高的应用前景。
