Tet-on诱导表达c-myc和SV40Tag的转基因小鼠肿瘤模型

目的研究Tet-on诱导表达c-myc和SV40Tag小鼠肿瘤模型的肿瘤发生和基因表达情况,探讨c-myc基因的作用。方法用pTRE2-c-myc单阳性转基因小鼠和Tet-on、pTRE2-SV40Tag双阳性转基因小鼠交配,后代检测得到Tet-onp、TRE2-SV40Tag、pTRE2-c-myc三阳性转基因小鼠,经强力霉素诱导一段时间以后,观察肿瘤的发生;通过RT-PCR、病理组织切片和磁共振等方法对肿瘤的发生部位和时相进行研究。结果Tet-on、pTRE2-SV40Tag、pTRE2-c-myc三阳性转基因小鼠①经诱导后发生肿瘤,且发瘤率和发瘤时间高于和短于Tet-on、pTRE2-SV40Tag双阳性转基因小鼠;②c-myc和SV40Tag基因在表达部位上有所不同。结论c-myc和SV40Tag基因同时表达与SV40Tag基因单独表达时相比,肿瘤发生明显增强,提示c-myc基因与肿瘤的发生有着密切关系。     

乙型肝炎病毒X基因转基因小鼠模型的建立及其应用研究进展

主要介绍了乙型肝炎病毒X基因转基因小鼠模型的建立,及其在HBx的反式激活作用和肝细胞癌等方面的研究进展。     

Pin1在皮肤组织中的表达以及可诱导转基因小鼠模型的建立

目的观察Pin1在皮肤中的表达情况,构建Pin1在皮肤中可诱导表达的转基因小鼠模型。方法将小鼠Pin1基因克隆到改造过的可与Myc标签蛋白融合的p TRE2载体中,并将线性化的DNA通过显微注射的方式构建TRE-Pin1小鼠。结果成功获得TRE-Pin1转基因首建鼠,该小鼠与上皮特异的K14-rt TA转基因小鼠配繁,获得Pin1在皮肤上皮特异性可诱导表达的双转基因鼠;通过将多西霉素(又名强力霉素,Doxycycline)加入饮水的方式诱导Pin1基因的表达,并通过Western blot,免疫组织化学等方式证明了Pin1蛋白在皮肤上皮中能特异性地过表达。我们还发现内源的Pin1在皮肤中主要表达于上皮细胞。结论成功构建了Pin1在皮肤中可诱导表达的转基因小鼠模型,为后续研究Pin1在皮肤中的功能奠定基础。     

肝癌转基因小鼠模型的应用研究进展北大核心CSCD

肝细胞癌是全球范围内的恶性肿瘤,由于其进展迅速、易于复发转移,早期诊断和有效治疗一直是临床难题,对于肝癌的发病机制也亟待进一步阐明。利用基因工程手段构建的肝癌转基因小鼠模型,为肝癌发病机制研究和药物筛选提供了宝贵的研究材料。结合经典研究与近年进展,对常用肝癌转基因小鼠模型的构建方法、模型特点、特别是应用研究状况进行了分类介绍,并展望了未来发展的方向。     

阿尔兹海默症转基因小鼠模型研究进展及评价

随着世界人口的老龄化,阿尔兹海默症已经成为严重威胁老年人健康的主要疾病之一,研究并建立可靠的阿尔兹海默症动物模型对于探明疾病的病因、发病机制及防治药物的开发均具有重要意义。本文就目前使用最为广泛和研究最为深入的转基因小鼠模型的病理、行为学变化特点及其在阿尔兹海默症研究中的应用和发现作一介绍。     

组织特异RNAi转基因小鼠模型的构建

RNAi是一种行之有效的基因沉默的新方法,被广泛地应用于基因功能的研究、疾病的治疗以及新型疫苗的研制等领域.本研究通过原核显微注射干扰载体的方法制备转基因小鼠.选用皮肤组织特异表达的人源角蛋白14（K14）基因启动子（2000bp）作为表达载体启动子,成功地驱动融合表达载体EGFP-shRNA进行干扰片段前体的转录,进而生成成熟的干扰片段,靶向小鼠BMP4基因使其发生沉默.所得到的转基因小鼠及其杂交后代经PCR和Southern杂交鉴定,结果表明外源基因准确无误地整合到小鼠基因组.Northern杂交结果证明,小干扰RNA在皮肤组织中有较高水平的表达,在肺和肠组织中有较低水平的表达.研究结果表明,利用PolⅡ型（K14）启动子驱动shRNA融合转录本的表达,在特定组织高表达siRNA,从而达到抑制特定组织目的基因表达的技术路线是可行的.同时为利用K14启动子进行毛囊相关基因干扰研究积累了基础数据,为制备组织特异抑制基因表达的转基因大家畜提供了一个参考方法.     

人类疾病转基因小鼠模型在基因治疗研究中的作用

基因治疗一度红红火火,激起公众极大的期望。但是初期试验远不如预期的好。科研人员理智地认识到目前阶段应把研究重点放在更基础的基因结构与功能、基因表达调控及基因载体构建研究等方面。建立人类疾病相关转基因小鼠模型是开展上述研究的一个重要基础,将为基因治疗的临床实施奠定坚实的基础 。     

四环素调控SV40Tag转基因小鼠模型的建立

目的构建四环素调控的SV40T转基因小鼠模型。方法同时显微注射外源基因p205-rtTA-C3和pTRE-Tag至FVB小鼠原核,注射受精卵移植到同期发情的假孕受体出生个体,经PCR和Southern检测获得阳性转基因小鼠。结果经PCR结合Southern检测得到rtTA和Tag双阳性转基因小鼠一只,rtTA单阳性两只和Tag单阳性一只。结论通过饮水给与四环素的双阳性小鼠可在卵巢中检测到Tag mRNA的表达。     

转基因小鼠在肿瘤研究中的应用

将可能激发肿瘤的基因导入小鼠受精卵,已制备了许多具有癌症倾向的小鼠系。这些小鼠能使人在整体水平系统研究不同癌基因在细胞分化、增殖中的作用以及在肿瘤发生中癌基因间的协同作用。同时,这些小鼠具有对病毒和化学致癌物敏感的倾向,因而为潜在致癌原测试,治疗和预防肿瘤药物的筛选提供了很有价值的研究模型。 过去20年,用分子克隆和基因转移等手段,将癌基因导入特定细胞以研究癌基因在细胞转化过程中的作用机制,取得了可喜进展。     

Generation and Characterization of a Transgenic Zebrafish Expressing the Reverse Tetracycline Transactivator

Conditional expression of a target gene during zebrafish development is a powerful approach to elucidate gene functions. The tetracycline-controlled systems have been successfully used in the modulation of gene expression in mammalian cells, but few lines of zebrafish carrying these systems are currently available. In this study, we had generated a stable transgenic zebrafish line that ubiquitously expressed the second-generation of reverse Tet transactivator （rtTA-M2）. Southern blotting analysis and high-throughput genome sequencing verifed that a single copy of rtTA-M2 gene had stably integrated into the zebrafish genome. After induction with doxycycline （Dox）, a strong green fluorescent protein （GFP） was seen in rtTA-transgenic eggs injected with pTRE--EGFP plasmids. The fluorescent signal gradually decreased after the withdrawal of Dox and disappeared. However, leaky expression of GFP was undetectable before Dox- induction. Additionally, transgenic embryos expressing rtTA-M2 exhibited no obvious defects in morphological phenotypes, hatching behavior and expression patterns of developmental marker genes, suggesting that rtTA-M2 had little effect on the development of transgenic zebrafish. Moreover, expressed Dickkopf-1 （DKK1） in pTRE-DKKl-injected embryos led to alterations in the expression of marker genes associated with Wnt signaling. Thus, this rtTA-transgenic zebrafish can be utilized to dissect functions of genes in a temporal manner.     

一种高效的单质粒模式四环素诱导表达系统的构建

现有的四环素诱导调控系统基于两个单独的质粒分别表达反式结合蛋白和外源基因.其缺点是在建立转基因定量表达动物模型时,需要制备和维持两个动物品系,再进行杂交才有可能获得双转基因后代,步骤繁琐,难度较大.针对上述缺陷,本研究尝试将反式蛋白rtTA表达框和低背景响应元件Ptight组装到同一个载体上,构建为严谨型单载体模式的诱导表达系统pTRE-Tight-rtTA,并通过两种报告基因的表达对其调控活性进行了研究.含有荧光素酶和绿色荧光蛋白的pTRE-Tight-rtTA-Luc和pTRE-Tight-rtTA-EGFP报告载体分别转染猪肾PK15细胞并经强力霉素处理,均可成功诱导报告基因的定量表达.在等摩尔转染条件下,单载体系统的诱导效率明显高于双载体系统（Dox-1 000 ng,10 倍;Dox-10 000 ng,8 倍）.该诱导型单载体系统的成功构建为外源基因的定量表达提供了新手段,为转基因定量表达动物模型的研究提供了新策略.     

时空表达可控的转基因动物模型调控体系的研究

目的在血管内皮细胞建立时空表达可控的转基因动物模型调控体系。方法培育两个配套的转基因动物品系,利用组织专一性启动子确保转基因表达的空间专一性,利用四环素诱导系统对转基因表达在时间上实施调控。结果将血管内皮细胞特异性表达的VE cadherin基因启动子与人工融合的转录因子tTA基因连接,建立转基因小鼠品系VE cadherin:tTA;将tetoperon的启动子与myrAkt1连接,建立转基因小鼠品系TET:myrAkt1。两系鼠杂交的子代,筛选的阳性纯合子,能可控性地在血管内皮细胞特异性表达目的基因Akt1PKB。结论利用VE cadherin基因启动子和tet off诱导表达系统,可以达到在时间上和空间上都能人为控制目的基因在血管内皮细胞上特异性表达的目的。     

A Transgenic Mouse Model with Inducible Tyrosinase Gene Expression Using the Tetracycline (Tet‐on) System Allows Regulated Rescue of Abnormal Chiasmatic Projections Found in Albinism

Congenital defects in retinal pigmentation, as in oculocutaneous albinism Type I (OCA1), where tyrosinase is defective, result in visual abnormalities affecting the retina and pathways into the brain. Transgenic animals expressing a functional tyrosinase gene on an albino genetic background display a correction of all these abnormalities, implicating a functional role for tyrosinase in normal retinal development. To address the function of tyrosinase in the development of the mammalian visual system, we have generated a transgenic mouse model with inducible expression of the tyrosinase gene using the tetracycline (TET‐ON) system. We have produced two types of transgenic mice: first, mice expressing the transactivator rtTA chimeric protein under the control of mouse tyrosinase promoter and its locus control region (LCR), and; second, transgenic mice expressing a mouse tyrosinase cDNA construct driven by a minimal promoter inducible by rtTA in the presence of doxycycline. Inducible experiments have been carried out with selected double transgenic mouse lines. Tyrosinase expression has been induced from early embryo development and its impact assessed with histological and biochemical methods in heterozygous and homozygous double transgenic individuals. We have found an increase of tyrosinase activity in the eyes of induced animals, compared with littermate controls. However, there was significant variability in the activation of this gene, as reported in analogous experiments. In spite of this, we could observe corrected uncrossed chiasmatic pathways, decreased in albinism, in animals induced from their first gestational week. These mice could be instrumental in revealing the role of tyrosinase in mammalian visual development.     

阿尔茨海默病转基因小鼠的特点和应用

建立动物模型的目的是在实验动物身上复制人类疾病的模型,用于研究人类疾病的病因、发病、病理变化以及疾病的预防和治疗。目前尚无理想的阿尔茨海默病（Alzheimer’s disease,AD）动物模型,AD实验动物模型的滞后在很大程度上制约了AD治疗药物的筛选。随着AD病因和发病机制研究的不断深入,更完善的AD动物模型也在陆续出现。近年来出现的转基因动物模型属于AD的病因模型,但也不能完整复制出AD的所有特征。最大的缺憾在于缺乏神经原纤维缠结（neurofibrillary tangles,NFTs）和在某些转基因模型中（尤其是单转基因模型）无广泛的神经元丢失。虽然用免疫组化方法检测到tau蛋白,但从未发现成对螺旋纤丝（paired helical filaments,PHF）。     

Variability of Inducible Expression across the Hematopoietic System of Tetracycline Transactivator Transgenic Mice

The tetracycline (tet)-regulated expression system allows for the inducible overexpression of protein-coding genes, or inducible gene knockdown based on expression of short hairpin RNAs (shRNAs). The system is widely used in mice, however it requires robust expression of a tet transactivator protein (tTA or rtTA) in the cell type of interest. Here we used an in vivo tet-regulated fluorescent reporter approach to characterise inducible gene/shRNA expression across a range of hematopoietic cell types of several commonly used transgenic tet transactivator mouse strains. We find that even in strains where the tet transactivator is expressed from a nominally ubiquitous promoter, the efficiency of tet-regulated expression can be highly variable between hematopoietic lineages and between differentiation stages within a lineage. In some cases tet-regulated reporter expression differs markedly between cells within a discrete, immunophenotypically defined population, suggesting mosaic transactivator expression. A recently developed CAG-rtTA3 transgenic mouse displays intense and efficient reporter expression in most blood cell types, establishing this strain as a highly effective tool for probing hematopoietic development and disease. These findings have important implications for interpreting tet-regulated hematopoietic phenotypes in mice, and identify mouse strains that provide optimal tet-regulated expression in particular hematopoietic progenitor cell types and mature blood lineages.     

24-脱氢胆固醇还原酶基因转基因小鼠血生化指标分析

目的建立全身表达24-脱氢胆固醇还原酶基因（Dhcr24）转基因小鼠动物模型,研究该基因过表达对小鼠代谢的影响。方法RT-PCR法克隆小鼠Dhcr24基因,把该基因插入CMV启动子下游,构建转基因表达载体,通过显微注射法建立Dhcr24转基因小鼠。PCR鉴定Dhcr24转基因小鼠的基因型,RT-PCR和Western Blot检测基因表达水平,血生化检测仪检测转基因小鼠血生化指标的改变。结果建立了2个不同表达水平的Dhcr24转基因小鼠品系,转入的Dhcr24基因在肝和脾组织中的表达高于内源的Dhcr24。血生化检测证实：乳酸脱氢酶（LDH）、总蛋白（TP）、白蛋白（Alb）和血肌酐（SCr）较野生型小鼠明显降低,而高密度脂蛋白胆固醇（HDL-c）和碱性磷酸酶（ALP）较野生型小鼠明显增加,并且Dhcr24转基因雌鼠的体重比野生型小鼠明显降低,均有显著差异。但Dhcr24转基因雄鼠各项指标与野生型小鼠相比没有显著差异。结论成功建立了全身表达Dhcr24转基因小鼠,并证实Dhcr24基因对雌性小鼠的体重和血生化指标,包括LDH,TP,Alb,SCr,HDL-c and ALP具有明显的影响。     

庚型肝炎病毒转基因小鼠的建立

利用受精卵原核显微注射的方法,产生了含有ＨＧＶ结构蛋白Ｃ、Ｅ１、Ｅ２及部分非结构蛋白ＮＳ２、ＮＳ３的转基因小鼠。得到１０只ｆｏｕｍｄｅｒ小鼠,其中有３只ｆｏｕｎｄｅｒ小鼠与正常小鼠交配后得到了整合有外源基因的Ｆ１代阳性小鼠。ＲＴ－ＰＣＲ的结果显示,外源基因可在ｆｏｕｎｄｅｒ小鼠及Ｆ１代小鼠的血液有核细胞及肝细胞内转录;组织病理学检查显示,某些转基因小鼠的肝细胞出现了水样变、脂肪变性及轻微炎性反应等     

microRNA转基因小鼠在心脏发育研究中的应用

microRNA（miRNA）参与调控胚胎心脏的发育,在心脏形态发生、心肌细胞生长及分化过程中发挥着极其重要的作用。通过转基因技术可以实现特异miRNA在心肌组织的过表达与敲除,据此建立的心肌特异性miRNA转基因小鼠模型可以在整体水平揭示miRNA心脏方面的功能。近年,以miRNA为研究对象的心肌特异性转基因小鼠模型数量不断增加。     

Inducible Nitric Oxide Synthase Up-Regulation in a Transgenic Mouse Model of Familial Amyotrophic Lateral Sclerosis

Mutations in copper/zinc superoxide dismutase (SOD1) are associated with a familial form of amyotrophic lateral sclerosis (ALS), and their expression in transgenic mice produces an ALS-like syndrome. Here we show that, during the course of the disease, the spinal cord of transgenic mice expressing mutant SOD1 (mSOD1) is the site not only of a progressive loss of motor neurons, but also of a dramatic gliosis characterized by reactive astrocytes and activated microglial cells. These changes are absent from the spinal cord of age-matched transgenic mice expressing normal SOD1 and of wild-type mice. We also demonstrate that, during the course of the disease, the expression of inducible nitric oxide synthase (iNOS) increases. In both early symptomatic and end-stage transgenic mSOD1 mice, numerous cells with the appearance of glial cells are strongly iNOS-immunoreactive. In addition, iNOS mRNA level and catalytic activity are increased significantly in the spinal cord of these transgenic mSOD1 mice. None of these alterations are seen in the cerebellum of these animals, a region unaffected by mSOD1. Similarly, no up-regulation of iNOS is detected in the spinal cord of age-matched transgenic mice expressing normal SOD1 or of wild-type mice. The time course of the spinal cord gliosis and iNOS up-regulation parallels that of motor neuronal loss in transgenic mSOD1 mice. Neuronal nitric oxide synthase expression is only seen in neurons in the spinal cord of transgenic mSOD1 mice, regardless of the stage of the disease, and of age-matched transgenic mice expressing normal SOD1 and wild-type mice. Collectively, these data suggest that the observed alterations do not initiate the death of motor neurons, but may contribute to the propagation of the neurodegenerative process. Furthermore, the up-regulation of iNOS, which in turn may stimulate the production of nitric oxide, provides further support to the presumed deleterious role of nitric oxide in the pathogenesis of ALS. This observation also suggests that iNOS may represent a valuable target for the development of new therapeutic avenues for ALS.