Induction and Analysis of Epithelial to Mesenchymal Transition

Epithelial to mesenchymal transition (EMT) is essential for proper morphogenesis during development. Misregulation of this process has been implicated as a key event in fibrosis and the progression of carcinomas to a metastatic state. Understanding the processes that underlie EMT is imperative for the early diagnosis and clinical control of these disease states. Reliable induction of EMT in vitro is a useful tool for drug discovery as well as to identify common gene expression signatures for diagnostic purposes. Here we demonstrate a straightforward method for the induction of EMT in a variety of cell types. Methods for the analysis of cells pre- and post-EMT induction by immunocytochemistry are also included. Additionally, we demonstrate the effectiveness of this method through antibody-based array analysis and migration/invasion assays.     

Induction of Interleukin 2-Responsiveness in Thymocytes of the Transgenic Mice Carrying lck-Transgene

The role of lck gene in T cell proliferation and differentiation was investigated with transgenic mice carrying human lck cDNA whose expression was regulated by the promoter of mouse H-2K^b and the enhancer element of mouse IgH. RNase protection assay revealed that the lck transgene was expressed in the thymus and spleen, whereas immunoblot analysis demonstrated that amounts of p56^lck in freshly isolated lymphoid organs were almost equal between transgenic mice and negative littermates. Cell-surface marker analyses of the thymocytes and peripheral lymphocytes revealed no remarkable difference between both groups. Notable finding is that the thymocytes from transgenic mice showed a significant proliferative response to the stimulation with IL-2, but not the thymocytes from negative littermates. Further analysis revealed that CD4⁺8^– single positive thymocytes proliferated in response to IL-2. While surface expression levels of IL-2Rα and IL-2Rβ of these CD4⁺8^– thymocytes from transgenic and control mice were almost equal before stimulation with IL-2, the expression of IL-2Rβ was induced only in transgenic thymocytes after stimulation with IL-2. Immunoblot analysis demonstrated that the expression of p56^lck of transgenic thymocytes was not down-reguated at 4 hr after stimulaion with IL-2, whereas p56^lck of control ones were not detectable any more at 4 hr after stimulation with IL-2. Moreover, in vitro kinase assay substantiated such unchanged expression of p56^lck in the thymocytes from transgenic mice: the kinase activities of p56^lck did not decrease in thymocytes from transgenic mice after stimulation with IL-2, while kinase activities of control ones were significantly down-regulated by stimulation of IL-2. These results suggested that a significant proliferative response found in the thymocytes from lck-transgenic mice after the stimulation with IL-2 was caused by a constitutive expression of p56^lck in these thymocytes even after the stimulation. Our findings, therefore, support a possibility that p56^lck may play a role in the IL-2R-mediated signaling system in CD4⁺8^– thymocytes.     

Vitamin D Supplementation Reduces Induction of Epithelial-Mesenchymal Transition in Allergen Sensitized and Challenged Mice

Asthma is a chronic disease of the lung associated with airway hyperresponsiveness (AHR), airway obstruction and airway remodeling. Airway remodeling involves differentiation of airway epithelial cells into myofibroblasts via epithelial-mesenchymal transition (EMT) to intensify the degree of subepithelial fibrosis. EMT involves loss in E-cadherin with an increase in mesenchymal markers, including vimentin and N-cadherin. There is growing evidence that vitamin D has immunomodulatory and anti-inflammatory properties. However, the underlying molecular mechanisms of these effects are still unclear. In this study, we examined the contribution of vitamin D on the AHR, airway inflammation and expression of EMT markers in the airways of mice sensitized and challenged with a combination of clinically relevant allergens, house dust mite, ragweed, and Alternaria (HRA). Female Balb/c mice were fed with vitamin D-sufficient (2000 IU/kg) or vitamin D-supplemented (10,000 IU/kg) diet followed by sensitization with HRA. The density of inflammatory cells in the bronchoalveolar lavage fluid (BALF), lung histology, and expression of EMT markers by immunofluorescence were examined. Vitamin D-supplementation decreased AHR, airway inflammation in the BALF and the features of airway remodeling compared to vitamin D-sufficiency in HRA-sensitized and -challenged mice. This was accompanied with increased expression of E-cadherin and decreased vimentin and N-cadherin expression in the airways. These results indicate that vitamin D may be a beneficial adjunct in the treatment regime in allergic asthma.     

Induction of Biochemical Differentiation in Three-Dimensional Collagen Cultures of Mammary Epithelial Cells from Virgin Mice

In order to reduce cellular complexity in the study of the controls of the biochemical differentiation of mammary gland epithelium, approximately 100-fold purified epithelial cells from the mammary glands of virgin BALB/c mice were grown in three-dimensional collagen gels, and formed colonies that resembled mammary ductules. Here we report the induction of a biochemical differentiation in these purified epithelial cells in response to appropriate hormonal signals, starting from the state in the virgin mammary gland and ending with the stage characteristic of lactation. Induction of the synthesis of caseins was examined as a marker of mammary functional differentiation using sensitive immunologic autoradiography. The cells were maximally induced by the combination of the hormones, insulin, prolactin, aldosterone, and hydrocortisone, in both serum-containing and essentially serum-free media. The induction required insulin and prolactin, and was enhanced by the presence of the steroids. The cellular distribution of the induction was general, inasmuch as three-quarters of the hormone-stimulated cells were casein-positive according to immunocytochemistry. In order to assess the role of the three-dimensional conformation in the induction process, the purified mammary epithelial cells were grown as monolayers on plastic and collagen-coated surfaces. In these two-dimensional cultures, the synthesis of casein was not induced, suggesting that cell shape, orientation, and multicellular organization are important parameters in the hormonal induction of the biochemical differentiation. The finding of the induction of differentiation-specific proteins in cultures of purified epithelial cells from virgin glands allows examination of the molecular mechanisms involved in the complete induction process in the virtual absence of fat cells, fibroblasts, and the complex assortment of biochemical constituents of the mammary fat pad.     

Overexpression of CD97 in Intestinal Epithelial Cells of Transgenic Mice Attenuates Colitis by Strengthening Adherens Junctions

The adhesion G-protein-coupled receptor CD97 is present in normal colonic enterocytes but overexpressed in colorectal carcinoma. To investigate the function of CD97 in colorectal carcinogenesis, transgenic Tg(villin-CD97) mice overexpressing CD97 in enterocytes were generated and subjected to azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis-associated tumorigenesis. Unexpectedly, we found a CD97 cDNA copy number-dependent reduction of DSS-induced colitis in Tg compared to wild-type (WT) mice that was confirmed by applying a simple DSS protocol. Ultrastructural analysis revealed that overexpression of CD97 strengthened lateral cell-cell contacts between enterocytes, which, in contrast, were weakened in CD97 knockout (Ko) mice. Transepithelial resistance was not altered in Tg and Ko mice, indicating that tight junctions were not affected. In Tg murine and normal human colonic enterocytes as well as in colorectal cell lines CD97 was localized preferentially in E-cadherin-based adherens junctions. CD97 overexpression upregulated membrane-bound but not cytoplasmic or nuclear β-catenin and reduced phospho-β-catenin, labeled for degradation. This was associated with inactivation of glycogen synthase kinase-3β (GSK-3β) and activation of Akt. In summary, CD97 increases the structural integrity of enterocytic adherens junctions by increasing and stabilizing junctional β-catenin, thereby regulating intestinal epithelial strength and attenuating experimental colitis.     

EGFR 对博莱霉素诱导小鼠肺纤维化中上皮- 间质转分化的影响

目的:探讨表皮生长因子受体(EGFR)在肺内的表达对博莱霉素(BLM)诱导小鼠肺纤维化中上皮-间质转分化的影响。方法:将40只4～6周龄C57BLB/c雄性小鼠随机分为正常对照组(气管滴入PBS),纤维化组(气管滴入BLM 3 mg/kg),EGFRRNAi组(气管滴入BLM 3 mg/kg+气管滴入siRNA 20μl)和RNAi阴性对照组(气管滴入BLM 3 mg/kg+气管滴入siRNA阴性对照20μl)。实验第10天处死小鼠,收获肺组织,检测羟脯氨酸含量;采用逆转录-聚合酶链反应(RT-PCR)法检测EGFR和α平滑肌肌动蛋白(α-SMA)mRNA的表达;肺组织切片行HE染色观察肺组织病理改变,免疫组化染色检测EGFR和α-SMA表达。结果:纤维化组EGFR和α-SMA两者的mRNA和蛋白表达均较正常对照组显著增加;RNAi组肺病理损伤较纤维化组减轻,气道上皮下胶原沉积及肺羟脯氨酸含量减少(P<0.05),肺组织EGFR和α-SMA两者的mRNA和蛋白表达均较纤维化组显著下降(P<0.05)。结论:在博来霉素诱导的肺纤维化中EGFR RNAi抑制EGFR活化,下调α-SMA的表达,减轻了博莱霉素诱导的肺纤维化病理改变。其抑制肺纤维化病理过程可能与其抑制上皮-间质转分化(EMT)有关。     

Generation of BAC Transgenic Epithelial Organoids

Under previously developed culture conditions, mouse and human intestinal epithelia can be cultured and expanded over long periods. These so-called organoids recapitulate the three-dimensional architecture of the gut epithelium, and consist of all major intestinal cell types. One key advantage of these ex vivo cultures is their accessibility to live imaging. So far the establishment of transgenic fluorescent reporter organoids has required the generation of transgenic mice, a laborious and time-consuming process, which cannot be extended to human cultures. Here we present a transfection protocol that enables the generation of recombinant mouse and human reporter organoids using BAC (bacterial artificial chromosome) technology.     

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.     

Cramp转基因小鼠的构建及鉴定

目的建立系统性表达Cramp转基因模型小鼠,为研究Cramp在衰老中的作用提供模型动物。方法把Cramp cDNA插入系统性表达CMV启动子下游,构建转基因表达载体,显微注射法建立Cramp转基因小鼠。PCR鉴定转基因小鼠的基因型,用RT-PCR和Western blotting方法筛选高表达品系。结果成功构建Cramp cDNA转基因载体,建立了Cramp转基因小鼠,通过RT-PCR和Western blotting方法筛选出3个高表达品系。结论建立了系统表达Cramp转基因小鼠,转入的Cramp基因在骨髓、脾脏、肝脏等组织高表达,为研究Cramp基因在衰老中的作用及机制提供了动物模型。     

Epithelial–Mesenchymal Transition in Kidney Tubular Epithelial Cells Induced by Globotriaosylsphingosine and Globotriaosylceramide

Fabry disease is a lysosomal storage disorder caused by deficiency of alpha-galactosidase A (α-gal A), which results in the deposition of globotriaosylceramide (Gb3) in the vascular endothelium. Globotriaosylsphingosine (lyso-Gb3), a deacylated Gb3, is also increased in the plasma of patients with Fabry disease. Renal fibrosis is a key feature of advanced Fabry disease patients. Therefore, we evaluated the association of Gb3 and lyso-Gb3 accumulation and the epithelial–mesenchymal transition (EMT) on tubular epithelial cells of the kidney. In HK2 cells, exogenous treatments of Gb3 and lyso-Gb3 increased the expression of TGF-β, EMT markers (N-cadherin and α-SMA), and phosphorylation of PI3K/AKT, and decreased the expression of E-cadherin. Lyso-Gb3, rather than Gb3, strongly induced EMT in HK2 cells. In the mouse renal mesangial cell line, SV40 MES 13 cells, Gb3 strongly induced phenotype changes. The EMT induced by Gb3 was inhibited by enzyme α-gal A treatment, but EMT induced by lyso-Gb3 was not abrogated by enzyme treatment. However, TGF-β receptor inhibitor (TRI, SB525334) inhibited the activation of TGF-β and EMT markers in HK2 cells with Gb3 and lyso-Gb3 treatments. This study suggested that increased plasma lyso-Gb3 has a crucial role in the development of renal fibrosis through the cell-specific induction of the EMT in Fabry disease, and that TRI treatment, alongside enzyme replacement therapy, could be a potential therapeutic option for patients with Fabry disease.     

上皮间质转化标记物及Snail在子宫内膜异位症中的表达

目的:研究上皮间质转化标志物(E-cadherin、β-catenin、vimentin)和Snail在子宫内膜异位症(endometriosis,EMs)中的表达。方法:选取40例EMs患者(实验组)异位内膜及在位内膜,同时获取20例非EMs患者(对照组)的正常子宫内膜,采用免疫组化法研究Snail、EMT上皮标志物(E-cadherin、β-catenin)、间质标志物(vimentin)在各内膜组织中的表达,并比较其表达水平。结果:EMs患者异位内膜和在位内膜的EMT上皮标志物E-cadherin、β-catenin表达均显著低于正常内膜的表达(P0.05);EMs患者异位内膜和在位内膜的EMT间质标志物vimentin表达均显著高于正常内膜的表达(P0.05);EMs患者异位内膜和在位内膜中Snail表达显著高于正常内膜的表达(P0.05)。结论:在子宫内膜异位症(EMs)中,Snail、vimentin表达上调,E-cadherin、β-catenin表达下调可能与子宫内膜异位症(EMs)的发生、发展及浸润转移有关。     

血管内皮生长因子 (VEGF1 83)转基因小鼠的建立(英文)

采用显微注射法 ,将一个由 1.3kb人感光细胞间维生素A类结合蛋白 (hIRBP)启动子区和人血管内皮生长因子 (hVEGF183)cDNA所构成的融合基因片段HIRV183导入 2 89枚ICR小鼠受精卵的雄性原核 .制备当代 (G0 )转基因小鼠 ,共得G0 代小鼠 17只 .经PCR和PCR Southern方法筛选得到 1只为hVEGF183转基因阳性小鼠 ,整合率为 5 9%,转基因总效率为 0 3%.将其与正常ICR小鼠交配 ,经PCR和dot blot杂交鉴定后代 (F1)小鼠阳性整合率为 4 5 9%.F1代兄妹之间进行交配 ,后代 (F2 )小鼠阳性整合率为 6 7 6 %.结果表明 ,外源基因hVEGF183整合在小鼠染色体的单一位点 ,为以后利用转基因动物的方法对VEGF这个新型异构体VEGF183进行深入研究打下了基础     

TIMP-1转基因小鼠纯合子的建立及建系

采用遗传学育种方法 ,使外源基因整合位点随机的基质金属蛋白酶抑制剂 1(TIMP 1)转基因小鼠成为单一整合位点的纯合子转基因小鼠而建立TIMP 1转基因小鼠品系 .通过受精卵原核显微注射方法 ,获得带有人TIMP 1基因的Founder小鼠 .将转基因小鼠与正常小鼠交配 ,得到子代小鼠 .通过PCR及Southern印迹等方法 ,检测TIMP 1DNA在转基因小鼠体内的整合情况 ,阳性率达5 0 %后 ,进行近亲交配 .提取小鼠组织总RNA ,Northern印迹分析阳性小鼠各组织外源性TIMP 1mRNA表达情况 ,以正常NIH小鼠做对照 .获得了 6代小鼠共 4 2 4只 ,其中PCR阳性鼠 2 72只 ,Southern阳性鼠 2 2 6只 ,纯合子转基因小鼠 12 8只 ;F4代后阳性率达到 95 %以上 .转基因小鼠TIMP 1基因表达情况在肾脏的丰度明显高于肝脏和脾脏 (P <0 0 1) ,而肝和脾之间并没有显著差异 (P>0 0 5 ) .外源基因在转基因小鼠体内可以稳定遗传 ,并得到了整合有TIMP 1基因的纯合子转基因小鼠 ,且在阳性的转基因小鼠体内在肾脏中特异性表达 ,为以后开展TIMP 1的肾脏病理生理研究提供了有用的手段     

SND1转基因小鼠的构建

目的:构建 SND1 过表达的转基因小鼠模型。方法:利用对小鼠 SND1 基因转录本构建 SND1 过表达载体pInsulator-CAG-3×FLAG-SND1,利用受精卵原核注射技术,将外源线性pInsulator-CAG-3×FLAG-SND1转基因载体注射到受精卵细胞核内,将存活受精卵进行胚胎移植制备 SND1 转基因小鼠,用PCR、RT-PCR技术鉴定转基因小鼠是否构建成功。结果:成功构建过表达 SND1 基因的转基因小鼠模型,为进一步研究 SND1 基因在动物体内的生物学功能奠定基础。     

EGF转基因鼠研究的展望

通过基因工程这一有力的工具,改变了信号转导级联后应中从配体本身开始,通过特异受体到达下游的单个或一组基因,石料研究信号转导的特殊性、互补性及重复性,已得到了大量关于肿瘤基因和生长因子的信息。转基因鼠和含有改变基因的鼠系被广泛应用于有关上皮生长因子受体（EGFR）及其配体。胰岛素样生长因子（IGF）受体及其结合蛋白的研究,综述了近年来EGF和IGF-I/胰岛素样生长因子结合蛋白（IGFBP）转基因鼠模型的主要进展,同时基于现有的转基因模型,概述了活体中EGF和IGFBP的最新研究成果,重点在于通过各种转基因及其因剔除模型的使用,研究EGF和IGF在生殖、生长和发育中的调节作用。     

人促红细胞生成素在转基因小鼠乳汁中表达

将山羊的β乳球蛋白启动子连接人促红细胞生成素基因,构建转基因表达载体。通过显微注射的方法转基因小鼠。经PCR斑点杂交和Southern杂交检测验证,获得4只转基因阳性小鼠,其中3只母鼠哺乳期收集乳汁,经EpoELISA检测为阳性。对4组转基因阳性小鼠的部分子代母鼠,经PCR和Southern杂交分析,又鉴定出6只获得遗传的阳性G1代母鼠以Dot-ELISA的方法检测,其中两只G1代母鼠乳汁中的Epo含量为0.5μg/mL。实验证实,867bp的β乳球蛋白启动子可以指导人促红细胞生成素在小鼠乳汁中表达。     

牛α—sl酪蛋白基因序列指导htPA突变体小基因在小鼠乳腺中的表达

将包括α－sl酪蛋白基因的启动子、LAtPA小基因、α－sl酪蛋白基因下游调控序列的融合基因经显微注射至小鼠的受精卵中,获得了5只转基因阳性鼠,其中1只转基因阳性雌鼠乳清中LAtPA的含量为0．18αg/ml,说明构建的LAtPA小基因能够正确表达出有生物活性的LAtPA, 在酪蛋白基因调控序列的指导下在小鼠乳汁中表达。