人bcl-xl转基因小鼠外源基因的复制及其传代稳定性

背景:近年的研究表明,在脑缺血再灌注损伤机制中,bcl-xl基因可能起着抗神经细胞凋亡的脑保护作用。目的:观察转bcl-xl基因小鼠外源基因的复制及传代稳定性问题。设计:以基因为观察对象。单位:华中科技大学同济医学院附属同济医院神经科和湖北省农科院畜牧兽医研究所。材料:实验于1999-10/2001-04在华中科技大学同济医学院附属同济医院完成。选取昆明种小鼠4只。方法:通过显微注射法建立转人bcl-xl基因小鼠,将PCR及Southern-blot检测整合阳性的小鼠与正常鼠交配并传代,然后检测子代小鼠外源基因的表达情况。作Southern-blot检测,结果证实第10,13,5,6号小鼠为整合阳性小鼠。以4只整合阳性小鼠作为首建者,分别与正常的昆明白小鼠交配繁殖传代,所生子代记为F1代,各系列的F1～F4代均采用阳性转基因小鼠与正常的昆明白小鼠交配繁殖传代方法,保持其杂合子形式。主要观察指标:检测外源基因的复制和传代的稳定性。结果:10号小鼠传代过程中外源基因PCR检测阳性率保持稳定,符合孟德尔遗传规律,表明外源基因能够稳定遗传。6号小鼠PCR阳性率呈轻微下降趋势,但仍能够保持相对稳定遗传。13号和5号小鼠PCR阳性率均呈明显的下降趋势,表明这2只小鼠存在外源基因遗传丢失现象。结论:应用基因组DNA做目的基因,可获得能够稳定遗传的转基因鼠系。     

乙型肝炎病毒转基因小鼠中外源基因整合的检测

目的了解乙型肝炎病毒DNA序列在乙型肝炎病毒转基因小鼠中的整合情况。方法用头尾相接的乙型肝炎病毒全序列基因,通过原核显微注射法产生转基因小鼠,用C区特异性引物扩增鼠尾DNA检测整合,对其中10只阳性鼠的扩增产物测序。结果128只仔鼠中,14只整合阳性。对10只阳性鼠测序,9只与所转基因序列完全相同,1只在1739、1740位缺失两个碱基。结论外源乙型肝炎病毒基因确定整合至小鼠基因组,多数为正常整合,但也存在缺失整合。     

载脂蛋白转基因小鼠的研究进展

转基因小鼠是当代生命科学尖端技术之一，也是研究基因结构与功能之间的关系等问题最有产的实验体系之一。本文综述了转脂蛋白转基因小鼠的制备方法，载脂蛋白转基因小鼠在脂质代谢异常和动脉粥样硬化病因和发病机理研究中的应用。     

HBV转基因小鼠HBsAg的表达

本文研究了两种不同繁育方法培育的乙型肝炎病毒（ＨｅｐａｔｉｔｉｓＢ Ｖｉｒｕｓ,ＨＢＶ）转砂眼习ＨＢｓＡｇ的表达情况。结果显示ＨＢＶ转基因纯合子小鼠ＨＢｓＡｇ表达率明显高于ＨＢＶ转基因杂合子小鼠。用ＨＢｓＡｇ疫苗免疫后发现表达ＨＢｓＡｇ的小鼠对ＨＢｓＡｇ形成免疫耐受,而虽有ＨＢＶ基因整合但不表达ＨＢｓＡｇ的小鼠对ＨＢｓＡｇ的不能形成免疫耐受。     

突变Myc基因骨髓特异性转基因小鼠肿瘤模型的建立及鉴定

目的 研究通过外源Myc基因转染造血细胞,实现骨髓特异性转基因并形成淋巴瘤的潜能.方法 造血细胞转染野生型与突变型Myc基因.移植入经~(60)Coγ射线照射的C57BL/6小鼠,观察小鼠形成肿瘤时间以及小鼠自然死亡时间,免疫组织化学染色法检测肿瘤类型;流式细胞术检测外源Myc基因在小鼠骨髓MNC中的表达;骨髓造血细胞、肝、脾、肿瘤组织行Myc免疫印迹法检测Myc在体内的表达情况.结果 Mye基因转基因后形成B细胞淋巴瘤,流式细胞术检测发现外源Myc基因可在造血细胞表达,突变型Myc基因阳性率高于野生型Myc基因,Myc基因转染骨髓造血细胞后,骨髓、肿瘤组织有较高表达,肝、肾组织则无表达.结论 外源Myc基因特异转染造血细胞可形成组织特异性转基因;突变型Myc基冈致瘤性高于野生型Myc基因.     

造血系统常用Cre转基因小鼠及其应用

Cre-lox重组系统包括Cre重组酶和lox位点两个要素.Cre酶能够特异地识别并催化lox位点间的片段进行重组,lox位点的方向和位置则决定Cre酶的功能效应.小鼠造血系统由多系各个发育阶段的造血细胞组成.它们是由骨髓内的造血干细胞（Hematopoietic stem cell,HSC）分化发育而来,而造血细胞的增殖发育是在骨髓微环境中进行的.目前有利用Cre-lox重组系统建立的多种转基因小鼠运用于造血系统的研究中,本文将讨论常用于造血系统的Cre转基因小鼠以及它们在造血系统研究中的应用.     

PML—RARα转基因小鼠发生急性早幼粒细胞白血病

为了从整体水平上研究ＰＭＬ－ＲＡＲα融合蛋白的致白血病作用,建立了仅在髓系细胞中表达ＰＭＬ－ＲＡＲα融合基因的转基因小鼠。通过表型分析发现一个单系的３只ｈＣＧ－ＰＭＬ－ＲＡＲα转基因小鼠在１－５个月时发生急性早幼粒细胞白血病,从而说明ＭＰＬ－ＲＡＲα融合基因的表达在白血病的发生中起着极为重要的作用。     

早期蛋白p52对人巨细胞病毒基因复制作用的实验研究

目的 :探讨HCMVDNA聚合酶辅助蛋白p5 2在病毒基因复制过程中的作用。方法 :采用体外实验方法建立HCMV感染细胞模型 ,在感染后不同时间段 ,FQ PCR法测定细胞内HCMVDNA拷贝数 ,免疫组化法检测病毒蛋白p5 2 ,计算机图像分析系统处理结果。同时光镜观察致细胞病变作用 ,电镜检查其超微结构的改变。结果 :感染后各组细胞内均能检测到HCMVDNA及p5 2表达 ,随感染时间延长 ,二者水平均升高 ,p5 2定位于感染细胞核内。与感染后 12h相比 ,此后各时段p5 2表达量均明显增高 (P <0 0 1) ;而至感染后 48h ,细胞内HCMVDNA量方明显高于感染后 12h(P <0 0 5 ) ,持续到感染晚期 ;同时细胞开始出现病变 ,并随感染时间延长、细胞内p5 2表达水平升高及HCMVDNA量增多而逐渐加重。结论 :早期蛋白p5 2在HCMVDNA复制过程中发挥重要作用 ,可有效促进病毒基因复制。     

载脂蛋白转基因小鼠的研究进展

转基因小鼠是当代生命科学尖端技术之一，也是研究基因结构与功能之间的关系等问题最有效的实验体系之一。本文综述了载脂蛋白转基因小鼠的制备方法，载脂蛋白转基因小鼠在脂质代谢异常和动脉粥样硬化病因和发病机理研究中的应用。     

Malaria in beta-thalassemic mice and the effects of the transgenic human beta-globin gene and splenectomy

To investigate the protective effects of beta-thalassemia against malaria, rodent malaria parasites were studied in C57BL/6J mice with beta-thalassemia, in mice in which the thalassemia had been transgenically corrected with the human beta A-globin gene, and in hematologically normal mice. In thalassemic mice, Plasmodium chabaudi adami infection was inhibited and peak parasitemia was variably delayed. In transgenically corrected mice, infection proceeded as in normal mice. Plasmodium berghei infection proceeded more rapidly in thalassemic mice, but survival was not different. Splenectomized normal mice displayed high-level parasitemia that peaked twice and persisted as a low-level parasitemia for more than 20 days after normal intact mice were free of all parasites. Splenectomized thalassemic mice showed a delay of 5 days in attaining peak parasitemia, but the parasitemia persisted as in normal splenectomized mice. Thus, for P. chabaudi, which displayed no preference for immature erythrocytes, beta-thalassemia offers enhanced resistance for the host. However, for P. berghei, which preferentially invades reticulocytes, thalassemia is not protective. The protective effects of the normal mouse spleen were observed, but the paradoxical facilitation of parasite growth by the thalassemic spleen is a new finding that will require further experimentation to explain. This new in vivo laboratory documentation of thalassemic protection against some rodent malaria parasites may serve as a useful model in further efforts to control this major infectious disease.     

MMP-1 drives immunopathology in human tuberculosis and transgenic mice

Mycobacterium tuberculosis can cause lung tissue damage to spread, but the mechanisms driving this immunopathology are poorly understood. The breakdown of lung matrix involves MMPs, which have a unique ability to degrade fibrillar collagens at neutral pH. To determine whether MMPs play a role in the immunopathology of tuberculosis (TB), we profiled MMPs and their inhibitors, the tissue inhibitor of metalloproteinases (TIMPs), in sputum and bronchoalveolar lavage fluid from patients with TB and symptomatic controls. MMP-1 concentrations were significantly increased in both HIV-negative and HIV-positive patients with TB, while TIMP concentrations were lower in HIV-negative TB patients. In primary human monocytes, M. tuberculosis infection selectively upregulated MMP1 gene expression and secretion, and Ro32-3555, a specific MMP inhibitor, suppressed M. tuberculosis-driven MMP-1 activity. Since the mouse MMP-1 ortholog is not expressed in the lung and mice infected with M. tuberculosis do not develop tissue destruction equivalent to humans, we infected transgenic mice expressing human MMP-1 with M. tuberculosis to investigate whether MMP-1 caused lung immunopathology. In the MMP-1 transgenic mice, M. tuberculosis infection increased MMP-1 expression, resulting in alveolar destruction in lung granulomas and significantly greater collagen breakdown. In summary, MMP-1 may drive tissue destruction in TB and represents a therapeutic target to limit immunopathology.     

Processing and proliferative effects of human progastrin in transgenic mice.

Incompletely processed gastrins have been postulated to play a role in growth of the gastrointestinal tract, but few studies have examined the effects of progastrin on mucosal proliferation in vivo. Human gastrin gene expression and progastrin processing were therefore studied in transgenic mice containing a human gastrin (hGAS) minigene, and compared to processing in mice bearing an insulin gastrin (INS-GAS) transgene that overexpresses amidated gastrin. Progastrin processing was studied using region-specific antisera and radioimmunoassays, biosynthetic labeling, immunoprecipitation, and HPLC. Proliferative effects due to overexpression of processed and unprocessed gastrin in INS-GAS and hGAS mice, respectively, were determined using routine histology and BrdU incorporation. The pancreatic islets of INS-GAS mice were able to produce carboxyamidated G-17, resulting in a twofold elevation of serum amidated gastrin, marked thickening of the oxyntic mucosa, and an increased BrdU labeling index (LI) of the gastric body. In contrast, livers of adult hGAS mice expressed abundant human gastrin mRNA and human progastrin but were unable to process this peptide to the mature amidated form, resulting in markedly elevated serum progastrin levels and normal amidated gastrin levels. Nevertheless, there was a marked increase in the BrdU labeling index of the colon in hGAS mice (LI 7.46+/-1.90%), as well as in INS-GAS mice (LI 6.16+/-1.17%), compared to age-matched, wild type control mice (LI 4.01+/-0.98%, P < 0.05). These studies suggest that incompletely processed gastrin precursors may contribute to colonic mucosal proliferation in vivo.     

Macrophage- and neutrophil-dominant arthritis in human IL-1 alpha transgenic mice

To study the effects of IL-1 alpha in arthritis, we generated human IL-1 alpha (hIL-1 alpha). Transgenic mice expressed hIL-1 alpha mRNA in various organs, had high serum levels of hIL-1 alpha, and developed a severe polyarthritic phenotype at 4 weeks of age. Not only bone marrow cells but also synoviocytes from knee joints produced biologically active hIL-1 alpha. Synovitis started 2 weeks after birth, and 8-week-old mice showed hyperplasia of the synovial lining layer, the formation of hyperplastic synovium (pannus) and, ultimately, destruction of cartilage. Hyperplasia of the synovial lining was due to the accumulation of macrophage-like cells expressing F4/80 molecules. hIL-1 alpha was widely distributed in macrophage- and fibroblast-like cells of the synovial lining cells, as well as synovial fluid monocytes. T and B cells were rare in the synovial fluid, and analysis of marker expression suggests that synoviocytes were directly histolytic and did not act as antigen-presenting cells. In the joints of these mice, we found elevated levels of cells of the monocyte/macrophage and granulocyte lineages and of polymorphonuclear neutrophils (PMNs), most of which expressed Gr-1, indicating that they were mature, tissue-degrading PMNS: Cultured synoviocytes and PMNs from these animals overexpress GM-CSF, suggesting that the hematopoietic changes induced by IL-1 and the consequent PMN activation and joint destruction are mediated by this cytokine.     

Tissue-specific expression and long-term deposition of human collagen VII in the skin of transgenic mice: implications for gene therapy

We report the isolation of a cosmid clone containing the entire human COL7A1 gene in one piece. The ability of the genomic sequences within this clone to direct tissue-specific expression of human collagen VII in transgenic mice was tested. The data show that the gene construct is capable of directing expression of collagen VII in the skin of fetal and neonatal transgenic mice. Expression of COL7A1 in these mice was widespread, in a pattern consistent with that found in human tissues and was in parallel with that of the endogenous mouse gene. Immunostaining, using human-specific antibodies, showed that human collagen VII protein was present at the skin basement membrane zone of the transgenic mice. Dermal extracts from 19-month-old transgenic mice contained mature human collagen VII protein, and fibroblasts derived from skin biopsies of these mice actively synthesized human collagen VII. The demonstration of successful and stable expression of human collagen VII in in vivo gene transfer is the first step towards the future development of therapeutic protocols for the rescue of keratinocyte function in severe blistering diseases such as dystrophic epidermolysis bullosa.     

Allelic exclusion in transgenic mice carrying mutant human IgM genes

Expression of the membrane-bound version of the human mu chain in transgenic mice results in the allelic exclusion of endogenous mouse Ig heavy chain genes (6). The secreted version of the human Ig transgene has no such effect. F1 hybrid animals that carry transgenes for both secreted and membrane-bound human mu chains produce both forms of the human heavy chain while strongly suppressing endogenous mouse mu expression. The simultaneous expression of the two rearranged transgenes in primary B cells suggests that allelic exclusion operates before the formation of a second functionally rearranged heavy chain gene in vivo.     

Combined hyperlipidemia in transgenic mice overexpressing human apolipoprotein Cl.

We have generated transgenic mice over-expressing human apolipoprotein CI (apo CI) using the native gene joined to the downstream 154-bp liver-specific enhancer that we defined for apo E. Human apo CI (HuCI)-transgenic mice showed elevation of plasma triglycerides (mg/dl) compared to controls in both the fasted (211 +/- 81 vs 123 +/- 52, P = 0.0001) and fed (265 +/- 105 vs 146 +/- 68, P < 0.0001) states. Unlike the human apo CII (HuCII)- and apo CIII (HuCIII)-transgenic mouse models of hypertriglyceridemia, plasma cholesterol was disproportionately elevated (95 +/- 23 vs 73 +/- 23, P = 0.002, fasted and 90 +/- 24 vs 61 +/- 14, P < 0.0001, fed). Lipoprotein fractionation showed increased VLDL and IDL + LDL with an increased cholesterol/triglyceride ratio (0.114 vs 0.065, P = 0.02, in VLDL). The VLDL apo E/apo B ratio was decreased 3.4-fold (P = 0.05) and apo CII and apo CIII decreased in proportion to apo E. Triglyceride and apo B production rates were normal, but clearance rates of VLDL triglycerides and postlipolysis lipoprotein "remnants" were significantly slowed. Plasma apo B was significantly elevated. Unlike HuCII- and HuCIII-transgenic mice, VLDL from HuCI transgenic mice bound heparin-Sepharose, a model for cell-surface glycosaminoglycans, normally. In summary, apo CI overexpression is associated with decreased particulate uptake of apo B-containing lipoproteins, leading to increased levels of several potentially atherogenic species, including cholesterol-enriched VLDL, IDL, and LDL.