慢病毒载体介导的转基因整合位点研究方法

慢病毒载体整合到宿主细胞的染色体上可以长期稳定表达,目前已成为基因治疗和转基因动物载体研究的热点.慢病毒载体整合的位置效应是影响外源基因表达的重要因素,慢病毒载体整合位点的研究是探索外源基因整合机制的手段之一.转基因整合位点研究的方法主要有5种:荧光原位杂交、个体基因组文库筛选法、反向PCR、接头PCR、锚定PCR.近来的研究后发现整合位点之间可能存在一些共同特征.     

优化反向PCR法对hTF转基因小鼠整合位点旁侧序列分析

自1982年世界上首次通过转基因动物技术获得＂巨鼠＂[1]以来,转基因动物的研究发展迅速。随着多种转基因动物的成功获得,研究者设想利用动物表达外源基因,以动物个体作为一个反应器来生产有价值的蛋白质。     

慢病毒载体法制备荧光素酶转基因小鼠

目的基于慢病毒介导的转基因方法制备荧光素酶（Luc）转基因小鼠。方法制备携带Luc基因的慢病毒,将其注入小鼠单细胞受精卵卵周隙以感染受精卵,然后将胚胎移植进假孕母鼠体内以获得仔鼠,应用小动物活体成像仪及PCR等在蛋白和DNA水平上筛选和鉴定Luc转基因小鼠。结果移植慢病毒隙感染后的成活胚胎63枚。将其移植至3只假孕母鼠,其中2只怀孕,共生仔鼠11只;利用小动物活体成像仪检测Luc表达,在蛋白水平证实11只F0代中,3只（命名为S1、S2、S3）表达Luc;DNA水平检测证实,3只Luc阳性小鼠的基因组中整合有外源转基因Luc。此外,Luc转基因首建鼠基因组中整合的Luc转基因可稳定遗传至下一代,并能正常表达。Luc转基因小鼠主要脏器如睾丸、肾脏、胃、肠、肺、脑、胸腺、肝脏和心脏等均可见Luc信号,但不同脏器间Luc强度有差异。结论成功制备Luc报告基因转基因小鼠。     

应用双色荧光原位杂交技术对转基因小鼠进行整合位点的染色体定位

目的 建立一种高度灵敏、特异的双色荧光原位杂交(dual-color fluorescence in situ hybridization,D-FISH)技术,对两种双阳性转基因小鼠外源基因进行整合位点的染色体定位.方法 对一只整合单纯疱疹病毒胸苷嘧啶激酶(herpes simplex virus thymidine kinase,HSV-tk)/增强型绿色荧光蛋白(enhanced green fluorescence protein,eGFP)的转基因小鼠以及两只整合RNA干扰载体(RNA interference,RNAi)的β654地中海贫血模型小鼠进行实验,脾脏细胞经培养后获得中期分裂相标本片,各加入适量生物素、地高辛标记探针混合液杂交,分别用罗丹明红色荧光抗体及FFIE绿色荧光抗体进行D-FISH检测.结果 两种转基因小鼠均能在同一个分裂相上同时检测到双色荧光信号.其中,HSV-tk/eGFP双阳性小鼠的分裂相上出现较强的绿色HSV-tk信号和红色eGFP信号,分别定位于染色体2E5-G3及8A2-A4;β654/RNAi双阳性小鼠检测到红色β654荧光信号及绿色RNAi荧光信号.经定位分析,β654均整合在染色体7D3-E2,RNAi病毒载体则是随机整合,其中一只鼠主要整合在1281位点,而另一只鼠主要整合在染色体1E2.3-1F、3A3两个位点.结论 用自行制备的DNA探针建立了高度灵敏、特异的D-FISH技术,同时结合G显带对双阳性转基因小鼠进行染色体基因定位.该技术平台的建立对于转基因动物和基因治疗动物模型的研究具有非常重要的意义.     

EB病毒BNLF—1基因转基因小鼠整合位点FISH检测的研究

本文应用荧光原位杂交技术研究了ＥＢ病毒潜伏膜蛋白基因（ＢＮＬＦ１） 在转基因小鼠染色体上的整合。结果：在转基因小鼠的单条染色体上检测到了杂交信号,检出率为３８ ．３ ％ ,表明该转基因已以单位点、多拷贝的形式稳定整合于转基因小鼠的染色体上。     

慢病毒载体法在制备转基因小鼠模型中的应用

目的改进慢病毒载体法制备转基因小鼠的操作技术,分别从病毒浓缩、受精卵显微注射进针点和如何提高病毒注射效率等方面探讨慢病毒显微注射技术的最佳方案。方法超速离心获得浓缩慢病毒,通过卵周隙显微注射技术感染小鼠受精卵,比较不同注射点显微注射后受精卵存活率及发育情况。结果受精卵1点和5点作为注射点的卵周隙注射组可有效避免注射针与卵膜的直接碰触,减少对受精卵的损伤,胚胎存活率较常规中轴3点作为注射点组显著提高(P<0.01)。适当的病毒滴度和注入量、操作细节、注射针口径等均可影响注射后受精卵存活率和感染率。结论卵周隙显微注射过程中选择适当的注射点以及部分操作的改进,可显著提高受精卵的存活率,为提高转基因小鼠模型的制备效率提供参考。     

双重引物PCR鉴定APPSWE转基因小鼠

本实验旨在探讨一种简单易行,能有效识别APPSWE转基因小鼠基因检测中假阴性结果的方法。在PCR体系中设计两对引物,一对为APP基因特异性引物,另一对为根据其内源性管家基因β-actin设置的参照引物。利用同一个PCR反应体系,对两对引物进行扩增。结果显示,双重引物PCR扩增的特异性片段与单引物扩增片段完全吻合,利用该法检出的转基因阳性率高于单引物PCR检出的转基因阳性率。本方法简单易行,能够有效识别以往利用单一PCR检测出现的假阴性结果,并且具有很好的特异性和灵敏性,值得在转基因小鼠鉴定实验中推广。     

小鼠CXCR4基因的克隆和慢病毒介导的表达

目的:克隆小鼠CXCR4基因并建立其慢病毒表达系统.方法:设计合成PCR引物, 从小鼠骨髓有核细胞来源的cDNA中扩增并克隆小鼠CXCR4基因的编码区.构建CXCR4-IRES-GFP表达单元后通过转染细胞, 观察GFP的表达证实其表达效能.然后建立慢病毒表达载体, 包装慢病毒后感染培养的细胞, 用流式细胞术分析其在被感染的细胞中的表达.结果:成功扩增了小鼠CXCR4基因的编码区.克隆入质粒载体后经DNA序列测定证实了其序列.通过转染细胞和流式细胞术以及荧光显微镜观察证实了CXCR4-IRES-GFP的表达效能.成功构建了CXCR4慢病毒表达载体, 感染细胞后经流式细胞术分析, 证实被感染的细胞可以表达小鼠CXCR4.结论:成功扩增、克隆了小鼠CXCR4基因, 并成功建立起其慢病毒表达系统, 为后续的基础和应用研究奠定了基础.     

慢病毒载体在转基因动物研制中的应用

慢病毒载体（lentiviral vector，LV）用于转基因技术与传统的DNA微注射相比具有操作简单、整合效率高、成本低廉等优点。与非慢病毒类反转录病毒载体相比，LV具有转基因表达效率高、对细胞周期没有选择性等优点。正因为LV具有独特的优点近年来LV转基因技术迅猛发展起来，多种LV转基因动物也接连诞生，文章从LV优点，构建，以及已获得的转基因动物制备方法研究入手，分析总结并提出了对未来的展望。     

慢病毒载体整合位点检测方法的系统适应性对照品初步研究

目的评估8E5细胞和CD19-CAR-Jurkat细胞作为慢病毒载体整合位点检测方法的系统适应性对照品的可行性。方法选择8E5细胞和CD19-CAR-Jurkat细胞, 通过有限稀释法挑选单克隆;建立数字PCR法检测8E5细胞内HIV-1的拷贝数和CD19-CAR-Jurkat细胞内CAR的拷贝数;采用高通量测序技术(全基因组重测序法、改良的基因组测序法和探针杂交捕获法)对8E5细胞和CD19-CAR-Jurkat细胞的整合位点进行检测, 并采用光学基因组图谱技术(optical genome mapping, OGM)对整合位点进行确认。结果经有限稀释法, 挑选出3个8E5细胞克隆和6个CD19-CAR-Jurkat细胞克隆。通过数字PCR及流式细胞术检测基因拷贝数, 确定8E5-D8和CD19-CAR-Jurkat 2-6作为候选细胞, 并扩增冻存。数字PCR检测结果显示, 8E5-D8细胞含有约1拷贝/细胞, CD19-CAR-Jurkat 2-6细胞含有约13拷贝/细胞;高通量测序结果显示, 8E5-D8细胞有1个整合位点, CD19-CAR-Jurkat 2-6细胞有13个整...     

原核注射产生转基因小鼠中的缺失整合

用心脏特异性启动子肌球蛋白轻链－２（ｍｙｏｓｉｏｎｌｉｇｈｔｃｈａｉｎ－２）ＭＬＣ２和糜酶结构基因相拼接构建ＭＬＣ２－糜酶融合基因，通过原核注射法产生转基因小鼠。用特异性引物对新生鼠鼠尾ＤＮＡ进行ＰＣＲ扩增初选，Ｓｏｕｔｈｅｒｎ印迹杂交确定整合有外源基因的阳性鼠。低熔点琼脂糖凝胶电泳回收阳性鼠ＰＣＲ扩增的ＤＮＡ片段，经测序后，与所转外源基因序列比较，发现缺失整合现象。     

外源基因在转基因小鼠中整合状况的分析

目的研究外源基因在转基因小鼠及其家系中的整合状况。方法采用PCR、定量PCR和荧光原位杂交(FISH)的方法对原代转基因小鼠中外源人凝血因子Ⅸ(hFⅨ)基因的整合和嵌合情况进行分析。使用PCR、直接测序法鉴定整合的外源基因多拷贝的连接方向和连接方式。结果7个家系中F0-8、F0-10和F0-11的后代中阳性个体比例明显低于50%,3个原代小鼠DNA中hFⅨ基因拷贝数分别只有子代中的66.2%、18.8%和28.3%。F0-11小鼠各脏器中嵌合比差异极大,且未见胚系特异性分布。不同个体间整合拷贝数差异极大,最少的F0-69为单拷贝,最多的F0-10有43个拷贝。而整合位点分析发现外源基因在随机分布中仍呈现一定的趋向性。PCR和测序结果证明所有小鼠中外源基因多拷贝均为头尾连接,连接的机制以粘性末端介导的连接为主,F0-13中还存在同源序列配对、断裂、修复介导的头尾连接。结论在整合有hFⅨ基因的转基因小鼠中多拷贝外源基因多以粘性末端介导的头尾连接方式整合在染色体的某些特定区域。     

Chymase Activities and Survival in Endotoxin-Induced Human Chymase Transgenic Mice

We examined the effects of overexpressed human chymase on survival and activity in lipopolysaccharide (LPS)-treated mice. Human chymase transgenic (Tg) and wild-type C57BL/6 (WT) mice were treated with LPS (0.03, 0.1 and 0.3 mg/day; intraperitoneal) for 2 weeks. Treatment with 0.03 mg LPS did not affect survival in either WT or Tg mice. WT mice were not affected by 0.1 mg/day of LPS, whereas 25% of Tg mice died. Survival of mice treated with 0.3 mg/day of LPS was 87.5% and 0% in WT and Tg, respectively. LPS-induced increases in chymase activity in the heart and skin were significantly greater in Tg than WT mice. These data suggest a possible contribution of human chymase activation to LPS-induced mortality.     

Ultrastructure and Electron Inununocytochemistry of Insulin-producing B-Cell Tumors from Transgenic Mice: Comparison with Counterpart Human Tumors

This paper reports on an ultrastructural and electron-microscopic immunocytochemical study of pancreatic B cells from normal mice, pancreatic B cells and derivative tumors from transgenic mice, and tissue from human pancreatic B-cell tumors. In normal and neoplastic B cells from both species, typical immature and mature β-granules (with spherical cores of variable density) were observed, whereas typical β-granules with a crystalloid core were only present in human B cells (normal and tumor). A small number of atypical granules were found in distinct neoplastic cells which contained no typical β-granules. The atypical granules were smaller (100–200 nm diameter) than typical β-granules (250–450 nm diameter) seen in other cells. Immunoreactivity for proinsulin was localized only to immature granules, whereas insulin and C-peptide immunoreactivities were demonstrated in atypical, immature, and mature granules. In transgenic mouse and human B-cell tumors, insulin immunoreactivity was consistently weaker than the immunostaining for C-peptide. An intragranular, topographic segregation of immunoreactive C-peptide was observed in a population of transgenic tumor cells. Our results showed similarities in antigenic distribution and only slight differences in morphology between human and mouse B cells. Therefore, the transgenic mouse system may prove to be an effective model for studying mammalian B-cell tumorigenesis.     

The Production of Transgenic Mice Expressing Human Cystathionine Beta-Synthase to Study Down Syndrome

Down syndrome (DS) is the most common genetic cause of significant cognitive disability. We hypothesize that by identifying metabolic alterations associated with cognitive impairment, it may be possible to develop medical or dietary interventions to ameliorate cognitive disabilities in persons with DS. Evidence suggests that one-carbon/transsulfuration (1C-TS) metabolism is abnormal in persons with DS. Cystathionine beta-synthase (CBS) plays a critical role in this metabolic system. The gene for CBS is on human chromosome 21, and there is evidence of elevated CBS enzyme activity in tissues and cells from individuals with DS. To analyze the possible role of CBS in Down syndrome, we have produced several lines of transgenic mice expressing the human CBS gene. We describe the use of Florescence Situ Hybridization (FISH) analysis to characterize the transgene insertion site for each line. Our initial expression analysis of each transgenic line by RT-PCR shows that the tissue specificity of human CBS mRNA levels in these mice may differ from the tissue specificity of mouse CBS mRNA levels in the same animals. These mice will be invaluable for assessing the regulation of the CBS gene and the role of CBS in cognition. They can also be used to develop therapies that target abnormalities in 1C-TS metabolism to improve cognition in persons with DS.Edited by Pierre L. Roubertoux     

Ultrastructure and Electron Inununocytochemistry of Insulin-producing B-Cell Tumors from Transgenic Mice: Comparison with Counterpart Human Tumors

This paper reports on an ultrastructural and electron-microscopic immunocytochemical study of pancreatic B cells from normal mice, pancreatic B cells and derivative tumors from transgenic mice, and tissue from human pancreatic B-cell tumors. In normal and neoplastic B cells from both species, typical immature and mature β-granules (with spherical cores of variable density) were observed, whereas typical β-granules with a crystalloid core were only present in human B cells (normal and tumor). A small number of atypical granules were found in distinct neoplastic cells which contained no typical β-granules. The atypical granules were smaller (100-200 nm diameter) than typical β-granules (250-450 nm diameter) seen in other cells. Immunoreactivity for proinsulin was localized only to immature granules, whereas insulin and C-peptide immunoreactivities were demonstrated in atypical, immature, and mature granules. In transgenic mouse and human B-cell tumors, insulin immunoreactivity was consistently weaker than the immunostaining for C-peptide. An intragranular, topographic segregation of immunoreactive C-peptide was observed in a population of transgenic tumor cells. Our results showed similarities in antigenic distribution and only slight differences in morphology between human and mouse B cells. Therefore, the transgenic mouse system may prove to be an effective model for studying mammalian B-cell tumorigenesis.     

Metformin Decelerates Aging and Development of Mammary Tumors in HER-2/neu Transgenic Mice

Transgenic FVB/N female mice carrying HER-2/neu mammary cancer gene received metformin (1200 mg/liter) with drinking water 5 days a week starting from the age of 2 months until natural death. Metformin slightly reduced food consumption, but did not change water consumption and dynamics of weight gain. Mean life span of mice increased by 8% (p<0.05), in 10% long-living mice it was prolonged by 13.1%, and the maximum life span was prolonged by 1 month under the effect of metformin in comparison with the control. The rate of populational aging decreased by 2.26 times. The total incidence of mammary adenocarcinoma and their multiplicity did not change under the effect of metformin, while the latency of tumor development increased and the mean diameter of tumors decreased. Hence, we first demonstrated a geroprotective effect of metformin and its suppressive effect towards the development of mammary tumors.__________Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 139, No. 6, pp. 691–694, June, 2005     

Increased Hepatic Cholesterol Accumulation in Transgenic Mice Overexpressing Human Secretory Phospholipase A2 Group IIA

It has been demonstrated in transgenic mice that the overexpression of human phospholipase A2 group IIA (sPLA2), an acute-phase reactant, is associated with depressed plasma cholesterol levels, altered lipoprotein compositions, and increased lipid depositions in aortic walls. It was the aim of the present study to investigate whether the reduced plasma cholesterol levels in sPLA2-transgenic mice may be due to an increased transfer of lipids from sPLA2-modified lipoproteins to the liver and/or other nonvascular tissues. Ten sPLA2-transgenic mice and an equal number of nontransgenic littermates were fed a cholesterol-enriched (1%) diet for 13 weeks. After autopsy, cholesterol and triglyceride concentrations were measured in homogenates of liver, spleen, kidney, and myocardial tissues. Compared to the nontransgenic controls, the sPLA2-transgenic mice exhibited significantly lower plasma cholesterol levels, which was due to a reduction in both HDL and beta-lipoprotein (LDL + beta-VLDL) cholesterol. Liver tissues from the transgenic mice were found to contain significantly increased concentrations of free and esterified cholesterol, which was not associated with increased triglyceride concentrations. Spleen, kidney, and heart tissues of the two animal groups showed no significant differences in cholesterol or triglyceride concentrations. The findings suggest that the overexpression of human secretory phospholipase A2 group IIA leads to an enhanced delivery of cholesterol from phospholipolysed lipoproteins to the liver. This mechanism is likely to contribute to the development of hypocholesterolemia observed in patients with inflammatory diseases.     

Diabetic Basement Membrane Thickening Does Not Occur in Myocardial Capillaries of Transgenic Mice When Metallothionein is Overexpressed in Cardiac Myocytes

Diabetic cardiomyopathy is a clinically distinct disease characterized by impaired cardiac function as a result of reduced contractility and hypertension‐induced athero‐ or arteriosclerosis. This may be due either to generalized vascular disease, tissue‐based injury such as focal cardiomyocyte dysmorphia, or microvascular damage manifested by myocardial capillary basement membrane (CBM) thickening. Hyperglycemia‐driven increases in reactive oxygen species (ROS) have been proposed to contribute to such damage. To address this hypothesis, we utilized light (LM) and transmission electron microscopy (TEM) to demonstrate cardiomyocyte morphology and myocardial CBM thickness in the left ventricles of four mouse genotypes: FVB (background Friend virus B controls), OVE (transgenic diabetics), Mt [transgenics with targeted overexpression of the antioxidant protein metallothionein (MT) in cardiomyocytes], and OVEMt (bi‐transgenic cross of OVE and Mt) animals. Mice were prepared for morphometric analysis by vascular perfusion. Focal myocardial disorganization was identified in OVE mice but not in the remaining genotypes. Not unexpectedly, myocardial CBM thickness was increased significantly in OVE relative to FVB (P < 0.05) and Mt (P < 0.05) animals (+28% and +39.5%, respectively). Remarkably, however, OVEMt myocardial CBMs showed no increase in width; rather they were ～3% thinner than FVB controls. Although the molecular mechanisms regulating CBM width remain elusive, it seems possible that despite a significant hyperglycemic environment, MT antioxidant activity may mitigate local oxidative stress and reduce downstream excess microvascular extracellular matrix (ECM) formation. In addition, the reduction of intra‐ and perivascular ROS may protect against incipient endothelial damage and the CBM thickening that results from such injury. Anat Rec, 296:480–487, 2013. © 2013 Wiley Periodicals, Inc.