基于报告基因和PPARγ信号通路的药物筛选模型的建立

目的　建立基于报告基因和PPARγ(peroxisomeprolif erator activatedreceptorγ)信号通路的药物筛选模型,用此模型筛选具有胰岛素增敏活性的小分子化合物。方法　五种细胞分别进行瞬时转染,将含有目的片段PPRE(peroxisomeproliferatorresponseelement)和报告基因荧光素酶(Luc)的质粒及表达PPARγ的质粒共转染到细胞中,通过测定荧光素酶活力来考察马来酸罗格列酮对PPARγ信号通路的影响,选取诱导表达倍数最高的细胞株建立模型。用其他类型核受体激动剂对此模型进行特异性考察。结果　293T细胞中,荧光素酶的表达受马来酸罗格列酮的诱导倍数最高,可达4 9倍,并呈现一定的剂量依赖关系,Z′因子为0 .72。而其他各类核受体激动剂的诱导表达率均在1倍左右。马来酸罗格列酮在转染剂量范围内无促进细胞增殖的作用。结论　马来酸罗格列酮对共转染报告基因质粒和表达PPARγ质粒的293T细胞Luc的表达具有较强的诱导作用,此模型具有较好的特异性和稳定性,适用于建立筛选PPARγ激动剂的高通量筛选模型。     

基于GADD153启动子的环境致癌物快速筛选系统研究

[目的]构建快速检测环境中痕量致癌物DNA损伤效应的重组人肝细胞株。[方法]构建含生长抑制与DNA损伤基因153(GADD153)启动子和萤光素酶报告基因的重组稳定转染人肝肿瘤HepG2细胞;发光检测不同致癌物对稳定转染细胞的DNA损伤效应;同时RT-PCR检测内源性GADD153mRNA的表达;彗星试验(Cometassay)检测DNA的损伤效应。[结果]稳定转染GADD153-LUC细胞株可检出多环芳烃、芳香胺、重金属、农药等已知环境致癌物以及实际水样中的含量。检测结果与彗星试验结果相比,大多数检测下限均低于彗星试验的检测限,其中对苯并芘、氯化镉和2-氨基芴的检测灵敏度分别高于彗星试验1000、300和100倍;对Aems试验不敏感的重金属、四氯化碳、氟化钠等重组细胞株具有较高的检测灵敏性。10μmol/L的氯化镉可诱导内源性GADD153mRNA和萤光素酶活性表达增加,相关分析表明两者具有良好的相关性(r2=0.9539)。[结论]重组细胞株GADD153-LUC细胞可快速检测环境中痕量污染物的DNA损伤效应。     

NGAL基因5′侧翼区转录调控元件的分段定位鉴定

目的 :对中性粒细胞明胶酶相关脂萼蛋白 (neutrophilgelatinase associatedlipocalin ,NGAL)基因 5′侧翼区的转录调控元件进行分段定位鉴定。方法 :以双荧光素酶报告基因检测系统检测NGAL基因 5′侧翼区 ( -14 3 1～ +84)转录调控元件与转录调控蛋白之间的相互作用。结果 :在NGAL基因 5′端 -945～ -65 8和 -65 7～ -4 172个区段发现了转录增强子元件与转录激活蛋白之间的相互作用 ,而在 -4 16～ -15 2区段则发现了转录沉默子元件与转录抑制蛋白之间的相互作用。结论 :在NGAL基因5′侧翼转录调控区可能至少存在着 2个转录增强子元件和 1个转录沉默子元件     

β-防御素-2荧光素酶报告基因载体及克罗恩突变体的构建

目的：构建人β-防御素-2（hBD-2）荧光素酶报告基因质粒及其克罗恩病（Crohn’s,CD）相关突变体,并检测其在人胚胎肾T细胞（HEK-293T）中的活化．方法：通过基因重组构建包含hBD-2启动子序列的报告基因质粒hBD-2—780-luc,再通过定点突变技术在启动子区（-233位点）引入变异点（G变为C）,构建突变体hBD-2-mut-luc;经酶切及测序验证后,将报告基因质粒和野生型NOD2／CARD15蛋白真核表达载体共转染到HEK一293T中,TNF—α刺激后测定双荧光素酶的表达．结果：酶切和测序证实,构建了重组体hBD-2-780-luc及其突变体hBD-2-mut—luc,两者均能表达荧光素酶活性,且明显高于空载体．结论：hBD-2报告基因质粒hBD-2-780-luc及其CD相关突变体hBD-2-mut—luc构建成功,并在细胞内活化表达荧光素酶．     

聚乙二醇化Exendin-4类似物受体亲和力测定方法的建立

基于荧光素酶报告基因法和本实验室前期构建的CHO-GLP-1R-CRE-Luc⁺检测模型细胞株,建立并优化了长效降糖多肽——聚乙二醇化Exendin-4类似物PE与GLP-1受体的亲和力测定方法,并对其进行了方法学验证。结果表明,当药物作用4 h,化学发光底物作用15 min,检测药物在5.7×10^-3~1.5×10³ nmol/L浓度区间内时,该检测方法的专属性和耐用性良好、准确度和精密度较高,符合《生物制品质量控制分析方法验证技术一般原则》的相关要求。本研究为该类GLP-1受体激动剂药物的快速评价与筛选奠定了基础。     

Luminopsins integrate opto- and chemogenetics by using physical and biological light sources for opsin activation

Luminopsins are fusion proteins of luciferase and opsin that allow interrogation of neuronal circuits at different temporal and spatial resolutions by choosing either extrinsic physical or intrinsic biological light for its activation. Building on previous development of fusions of wild-type Gaussia luciferase with channelrhodopsin, here we expanded the utility of luminopsins by fusing bright Gaussia luciferase variants with either channelrhodopsin to excite neurons (luminescent opsin, LMO) or a proton pump to inhibit neurons (inhibitory LMO, iLMO). These improved LMOs could reliably activate or silence neurons in vitro and in vivo. Expression of the improved LMO in hippocampal circuits not only enabled mapping of synaptic activation of CA1 neurons with fine spatiotemporal resolution but also could drive rhythmic circuit excitation over a large spatiotemporal scale. Furthermore, virus-mediated expression of either LMO or iLMO in the substantia nigra in vivo produced not only the expected bidirectional control of single unit activity but also opposing effects on circling behavior in response to systemic injection of a luciferase substrate. Thus, although preserving the ability to be activated by external light sources, LMOs expand the use of optogenetics by making the same opsins accessible to noninvasive, chemogenetic control, thereby allowing the same probe to manipulate neuronal activity over a range of spatial and temporal scales.Optogenetics, which offers precise temporal control of neuronal activity, has been used widely in experimental neuroscience. Although optogenetic probes are indispensable tools, conventionally their application in vivo requires invasive optical fiber implants and thus imposes significant limitations for clinical applications and for applications involving multiple brain regions (1). On the other hand, chemogenetics can modulate neuronal activity throughout the brain using a genetically targeted actuator when combined with a systemically administered small molecule. Although systemic injection of a small molecule is far less invasive than implantation of fiber optics, chemogenetics has its own limitations, such as slow response kinetics and dependence on G protein signaling, which potentially elicits unwanted secondary effects in target neurons (2).Combining the distinct advantages of opto- and chemogenetic approaches would create unprecedented opportunities for interrogation of neural circuits at a wide range of spatial scales. To allow manipulation of activity of dispersed neuronal populations using optogenetic probes without fiber-optic implants, we proposed a different approach where bioluminescence—biological light produced by enzymatic reaction between a protein, luciferase, and its diffusible substrate, luciferin—activates an opsin, which is tethered to the luciferase (3). After injection to the peripheral bloodstream, luciferin reaches a target in the brain because it crosses the blood–brain barrier (4). Light is generated by the luciferase and then activates the opsin, resulting in activation (in case of channelrhodopsins) or inhibition (in case of proton or chloride pumps) of the target neurons. Capitalizing on the major advantage of opsins as powerful generators of electrical current, our approach integrates opto- and chemogenetic methods by preserving conventional photoactivation of opsins where desired, while at the same time providing chemogenetic access to the same molecules, thus allowing manipulation of neuronal activity over a range of spatial and temporal scales in the same experimental animal.Initial proof-of-concept studies showed that Gaussia luciferase (GLuc)-emitted light is able to activate opsins when the two molecules are fused together (luminescent opsin or luminopsin, LMO) (3). Here we report a set of new LMOs, incorporating brighter versions of GLuc, with significantly improved performance. We found that the improved LMOs could modulate neuronal activity via bioluminescence in vitro, ex vivo, and in vivo and could elicit behaviors in freely moving mice.     

Plasmodium liver load following parenteral sporozoite administration in rodents

One of the bottlenecks in the development of a whole sporozoite malaria vaccine is the route and method of sporozoite administration. Immunization and challenge of human volunteers by mosquito bites is effective, but cannot be used as a vaccine. Intravenous immunization with sporozoites is effective in rodents and non-human primates, and being studied in humans, but is not yet used for licensed vaccines for infectious diseases. Intradermal and subcutaneous immunization regimens show a strong decrease in protective efficacy, which in rodents, is associated with a decreased degree of parasite liver infection during immunization. The objective of this study was to explore alternative routes of sporozoite administration to increase efficiency of liver infection. Using in vivo imaging, we found that IM injection of sporozoites resulted in a greater parasite liver load compared to ID and SC injection. The use of small inoculation volumes and multiple injections further increased the subsequent liver load. These observations were corroborated in a Plasmodium yoelii model using cryopreserved sporozoites administered ID. Our findings provide a rationale for the design of clinical trials to optimize needle and syringe administration of Plasmodium falciparum sporozoites.     

人脂联素基因启动子荧光素酶报告基因载体的构建

目的:克隆不同长度人脂联素基因(AD)启动子片段,构建含人AD启动子片段的荧光素酶报告基因载体并进行测序鉴定。方法:利用PCR技术从人全血基因组DNA中扩增出AD启动子片段,经纯化酶切后克隆入载体pGL-3 basic中,形成重组质粒,筛选阳性克隆进行测序,并与GenBank比对。结果:从人全血基因组DNA中PCR扩增得到1.1 kb和2.1 kb AD启动子片段,构建2种报告基因载体,将其命名为AD promoter1.1-pGL-3 basic和AD promoter2.1-pGL-3 basic,经测序证实所插入的目的片段与GenBank检索的人AD启动子序列99.6%匹配。结论:成功构建了含人AD启动子片段的报告基因载体。     

一种基于抗氧化反应元件的抗氧化药物筛选模型的制备

目的 利用抗氧化反应元件(ARE)调控荧光素酶(Luc)报告基因的表达水平,建立抗氧化药物筛选细胞模型.方法 构建由ARE调控Luc表达的重组质粒载体pARE-Luc-Neo,使用FuGENE@HD转染剂将重组质粒转染人胚肾上皮Hek293细胞,通过G418进行筛选,使用稀释法挑选阳性单克隆细胞,经抗氧化蛋白诱导剂TBHQ诱导,检测细胞中Luc的活性,筛选Luc高活性的单克隆细胞株.利用白藜芦醇和姜黄素评价阳性克隆的筛选效果,观察5个中药单体穿心莲内酯、隐丹参酮、水飞蓟素、苦参碱和虎杖苷在不同浓度(0、3.125、6.25、12.5、25、50、100μmol/L)时对Luc表达水平的影响.结果 通过检测Luc活性,筛选获得Hek293-ARE,该细胞中的Luc的表达水平受ARE调控,且在一定范围内与诱导剂的浓度呈相关性.穿心莲内酯、隐丹参酮与水飞蓟素有较好的诱导效果.结论 建立的抗氧化药物细胞筛选模型可有效地、高通量地用于抗氧化药物的初步筛选.