CORE--TRANSGENIC AND CHIMERIC MOUSE FACILITY

通过将外源DNA引入受精卵母细胞来产生转基因小鼠(1)，已经产生了一系列令人兴奋的新的体内实验模型，用于研究发育、遗传疾病、基因表达的转录控制、基因表达的组织特异性和肿瘤发生。对于在细胞中正常表达的基因，没有足够的组织培养对应基因，转基因动物的产生是目前定位基因控制元件和研究基因功能的最佳手段(2)。其他技术，如靶向肿瘤发生(3)，发育小鼠细胞连接的靶向消融（4,5），调节转基因表达的二元系统(6)，以及利用噬菌体P1的Cre和loxP系统进行同源重组(7)，正在完善转基因技术的应用。基因靶向（8,9）和转基因小鼠模型对肝脏和消化系统疾病的许多方面的理解产生了重大影响。例如，基于对各种转基因小鼠模型的分析，对肠神经系统的理解和对Hirschspring病的神经节巨结肠的病理生理学的了解有所增加。这些包括靶向破坏内皮素-3或其受体内皮素B、酪氨酸激酶RET和胶质细胞系来源的神经营养因子的小鼠。这些研究表明，至少有两种不同的机制可导致终末肠神经节病（10）。同样，神经元型一氧化氮合成酶（nNOS）的缺乏也会导致小鼠胃扩张和胃停滞（11）。在转基因小鼠中发现了胃泌素的过表达和缺乏，证实了胃泌素作为壁细胞功能的关键调节剂的作用，但也指出了其他意想不到的功能，如结肠增殖（12,13）。免疫失衡导致肠道炎症的实验小鼠模型，如白细胞介素-10缺失小鼠（14）或TNF过表达小鼠（15），开始为克罗恩病等炎症性肠病提供小鼠模型。肠道上皮细胞凋亡可以在p53缺失小鼠等转基因小鼠模型中进行研究，但不能在组织培养模型中进行研究（16）。对转基因小鼠系的研究有助于理解肝脏再生启动的机制，并提供了许多肝脏表达基因的基因调控和功能的关键信息（17）。很明显，消化器官的复杂性非常适合在转基因和靶向小鼠模型中进行生理分析。转基因和嵌合小鼠设施的主要功能是提供一个集中的实验室，该实验室将产生无感染的转基因创始型或嵌合型小鼠，这些小鼠携带中心个别项目特定感兴趣的转基因或基因敲除。这些技术要求高的程序的集中，提高了reach项目的效率，降低了成本。鼠标模型的生成也促进了中心成员之间的协作和互动。

The generation of transgenic mice through the introduction of foreign DNA into the fertilized mouse oocyte (1), has resulted in the development of an exciting array of new in vivo experimental models for the study of development, genetic disorders, transcriptional control of gene expression, tissue specificity of gene expression, and oncogenesis. For genes normally expressed in cells without adequate tissue culture counterparts, the generation of transgenic animals is the best current means of localizing gene control elements and studying gene functions (2). Additional techniques such as targeted oncogenesis (3), targeted ablation of cell linkages in the developing mouse (4,5), binary systems for regulating transgene expression (6), and homologous recombination using the Cre and loxP system from bacteriophage P1 (7) are refining the applications of transgenic technology. Gene-targeted (8,9) and transgenic mouse models have had a major impact on the understanding of many aspects of liver and digestive disorders. For example, an increased understanding of the enteric nervous system and insights into the pathophysiology of a ganglionic megacolon of Hirschspring's disease have accrued based upon the analysis of a varies of transgenic mouse models. These include mice with targeted disruptions of endothelin-3 or its receptor endothelin B, the tyrosine kinase RET and glial cell line-derived neurotrophic factor. These studies have led to the concept that at least two different mechanisms can cause aganglionosis of the terminal bowel (10). Similarly, deficiency of neuronal nitric oxide synthetase (nNOS) has been shown to induce to gastric dilatration and stasis in mice (11). Over-expression and deficiency of gastrin have been developed in transgenic mice confirming gastrin's role as a key regulator of parietal cell function, but also pointing to additional, unexpected functions such as colonic proliferation (12, 13). Experimental mouse models of immune imbalance leading to intestinal inflammation such as with the interleukin-10 null mice (14) or TNF over-expressing mice (15) begin to provide mouse models for inflammatory bowel diseases such as Crohn's disease. Intestinal epithelial apoptosis can be studied in transgenic mouse models such as p53 null mice, but not in tissue culture models (16). Studies of transgenic mouse lines have contributed to an understanding of the mechanisms involved in the initiation of liver regeneration and have provided critical information about the gene regulation and function of many liver- expressed genes (17). It is clear that the complexity of the digestive organs is well suited to physiologic analysis in transgenic and targeted mouse models. The primary function of the Transgenic and Chimeric Mouse Facility is to provide a centralized laboratory that will generate infection-free, transgenic founder or chimeric strains of mice carrying transgenes or gene knock-outs of specific interest to individual projects in the Center. The centralization of these technically demanding procedures results in enhanced efficiency and cost reduction for reach project. The generation of mouse models facilitates collaborations and interactions among the Center members as well.