CORE--TRANSGENIC AND CHIMERIC MOUSE FACILITY

通过将外源DNA引入受精小鼠卵母细胞而产生转基因小鼠（1），已经导致开发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。对于通常在细胞中表达而没有足够的组织培养对应物的基因，转基因动物的产生是定位基因控制元件和研究基因功能的最佳当前手段（2）。 其他技术如靶向肿瘤发生（3）、发育中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）以及使用来自噬菌体P1的Cre和loxP系统的同源重组（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，增加肠神经系统的理解和洞察神经节巨结肠的Hirschspring病的病理生理学已经积累的基础上分析的各种转基因小鼠模型。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和神经胶质细胞系衍生的神经营养因子的小鼠。这些研究导致了至少两种不同机制可以导致末端肠无神经节细胞症的概念（10）。类似地，神经元型一氧化氮合成酶（nNOS）的缺乏已被证明会诱导小鼠的胃排空和停滞（11）。在转基因小鼠中已经出现了胃泌素的过度表达和缺乏，这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）。导致肠道炎症的免疫失衡的实验小鼠模型，例如白细胞介素-10缺失小鼠（14）或TNF过表达小鼠（15），开始提供炎性肠病例如克罗恩病的小鼠模型。肠上皮细胞凋亡可以在转基因小鼠模型如p53缺失小鼠中进行研究，但不能在组织培养模型中进行研究（16）。转基因小鼠品系的研究有助于理解肝再生启动机制，并提供了关于许多肝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，将产生无感染，转基因创始人或嵌合小鼠品系携带转基因或基因敲除在中心的个别项目的具体利益。这些技术上要求很高的程序的集中化导致了reach项目的效率提高和成本降低。小鼠模型的生成也促进了中心成员之间的合作和互动。

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.