OBJECTIVE To identify the mechanisms by which the formyl peptide receptor 2(FPR2)mediates both inflammatory and anti-inflammatory signaling in an agonist-dependent manner.METHODS Cells expressing FPR2 were incubated w...OBJECTIVE To identify the mechanisms by which the formyl peptide receptor 2(FPR2)mediates both inflammatory and anti-inflammatory signaling in an agonist-dependent manner.METHODS Cells expressing FPR2 were incubated with weak agonists,Aβ42 and Ac2-26,before stimulation with a strong agonist,WKYMVm.Calcium mobilization,c AMP inhibition and MAP kinase activation were measured.Intramolecular FRET were determined using FPR2 constructs with an ECFP attached to the C-terminus and a Fl As H binding motif embedded in the first or third intracellular loop(IL1 or IL3,respectively).RESULTS Aβ42 did not induce significant Ca^(2+) mobilization,but positively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction in a dose-variable manner within a narrow range of ligand concentrations.Treating FPR2-expressing cells with Ac2-26,a peptide with anti-inflammatory activity,negatively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction.Intramolecular FRET assay showed that stimulation of the receptor constructs with Aβ42 brought the C-terminal domain closer to IL1 but away from IL3.An opposite conformational change was induced by Ac2-26.The FPR2 conformation induced by Aβ42 corresponded to enhanced ERK phosphorylation and attenuated p38 MAPK phosphorylation,whereas Ac2-26 induced FPR2 conformational change corresponding to elevated p38 MAPK phosphorylation and reduced ERK phosphorylation.CONCLUSION Aβ42 and Ac2-26 induce different conformational changes in FPR2.These findings provide a structural basis for FPR2 mediation of inflammatory vs anti-inflammatory functions and identify a type of receptor modulation that differs from the classic positive and negative allosteric modulation.展开更多
有学者提出了一种在压缩语音编码过程中进行QIM(Quantization Index Modulation)隐写的方法.该方法可用于在G.729A压缩语音流中高隐蔽性地嵌入秘密信息,研究其隐写分析方法很有必要.本文首先分析了QIM隐写对G.729A码流造成的显著性特征...有学者提出了一种在压缩语音编码过程中进行QIM(Quantization Index Modulation)隐写的方法.该方法可用于在G.729A压缩语音流中高隐蔽性地嵌入秘密信息,研究其隐写分析方法很有必要.本文首先分析了QIM隐写对G.729A码流造成的显著性特征变化,发现该种隐写将使码流中LPC滤波器的量化索引(码字)发生转移,并导致码字分布的不均衡性及相关性特性发生改变.本文设计了统计模型,实现了对码字分布特性的量化特征抽取;结合支持向量机,本文构造了用于隐写检测的集成分类器系统.实验结果显示本文方法能够在低于30ms的时间内,获得超过98%的检测准确率,实现了对QIM隐写的快速有效检测.展开更多
G蛋白偶联受体(G protein coupled receptors,GPCR)是目前研究最广泛的药物靶标蛋白.超过30%的已上市药物以GPCR为靶点.这一重要的跨膜蛋白家族及其分子结构和功能一直是各大制药公司和学术界的研究热点.近年来,GPCR X射线衍射晶体学方...G蛋白偶联受体(G protein coupled receptors,GPCR)是目前研究最广泛的药物靶标蛋白.超过30%的已上市药物以GPCR为靶点.这一重要的跨膜蛋白家族及其分子结构和功能一直是各大制药公司和学术界的研究热点.近年来,GPCR X射线衍射晶体学方面取得了重大突破,已有30多个A类GPCR的高分辨率结构得到了解析.这为基于结构的药物设计和GPCR功能研究提供了结构依据,以及新的药物靶点和药物设计策略.利用这些结构,计算机模拟方法也在GPCR的结构和功能研究中得到了广泛应用,并在过去几年中取得了一些突破性的成果.这些研究进展深化了对GPCR的动态结构、配体识别和激活机制等方面的理解.简要回顾近年来对A类GPCR的结构和功能研究方面的最新进展,并特别对计算机辅助药物设计和分子模拟在这方面的应用进行重点讨论.展开更多
基金supported by National Natural Science Foundation of China(31470856 to RDY)the Science and Technology Development Fund of Macao(FDCT 072/2015/A2)the University of Macao(SRG2015-00047-ICMS-QRCM)
文摘OBJECTIVE To identify the mechanisms by which the formyl peptide receptor 2(FPR2)mediates both inflammatory and anti-inflammatory signaling in an agonist-dependent manner.METHODS Cells expressing FPR2 were incubated with weak agonists,Aβ42 and Ac2-26,before stimulation with a strong agonist,WKYMVm.Calcium mobilization,c AMP inhibition and MAP kinase activation were measured.Intramolecular FRET were determined using FPR2 constructs with an ECFP attached to the C-terminus and a Fl As H binding motif embedded in the first or third intracellular loop(IL1 or IL3,respectively).RESULTS Aβ42 did not induce significant Ca^(2+) mobilization,but positively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction in a dose-variable manner within a narrow range of ligand concentrations.Treating FPR2-expressing cells with Ac2-26,a peptide with anti-inflammatory activity,negatively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction.Intramolecular FRET assay showed that stimulation of the receptor constructs with Aβ42 brought the C-terminal domain closer to IL1 but away from IL3.An opposite conformational change was induced by Ac2-26.The FPR2 conformation induced by Aβ42 corresponded to enhanced ERK phosphorylation and attenuated p38 MAPK phosphorylation,whereas Ac2-26 induced FPR2 conformational change corresponding to elevated p38 MAPK phosphorylation and reduced ERK phosphorylation.CONCLUSION Aβ42 and Ac2-26 induce different conformational changes in FPR2.These findings provide a structural basis for FPR2 mediation of inflammatory vs anti-inflammatory functions and identify a type of receptor modulation that differs from the classic positive and negative allosteric modulation.
文摘有学者提出了一种在压缩语音编码过程中进行QIM(Quantization Index Modulation)隐写的方法.该方法可用于在G.729A压缩语音流中高隐蔽性地嵌入秘密信息,研究其隐写分析方法很有必要.本文首先分析了QIM隐写对G.729A码流造成的显著性特征变化,发现该种隐写将使码流中LPC滤波器的量化索引(码字)发生转移,并导致码字分布的不均衡性及相关性特性发生改变.本文设计了统计模型,实现了对码字分布特性的量化特征抽取;结合支持向量机,本文构造了用于隐写检测的集成分类器系统.实验结果显示本文方法能够在低于30ms的时间内,获得超过98%的检测准确率,实现了对QIM隐写的快速有效检测.
文摘G蛋白偶联受体(G protein coupled receptors,GPCR)是目前研究最广泛的药物靶标蛋白.超过30%的已上市药物以GPCR为靶点.这一重要的跨膜蛋白家族及其分子结构和功能一直是各大制药公司和学术界的研究热点.近年来,GPCR X射线衍射晶体学方面取得了重大突破,已有30多个A类GPCR的高分辨率结构得到了解析.这为基于结构的药物设计和GPCR功能研究提供了结构依据,以及新的药物靶点和药物设计策略.利用这些结构,计算机模拟方法也在GPCR的结构和功能研究中得到了广泛应用,并在过去几年中取得了一些突破性的成果.这些研究进展深化了对GPCR的动态结构、配体识别和激活机制等方面的理解.简要回顾近年来对A类GPCR的结构和功能研究方面的最新进展,并特别对计算机辅助药物设计和分子模拟在这方面的应用进行重点讨论.
