Novel transgenic mouse models for human p450 research

描述(由申请人提供)：长期目标是确定人体微粒体细胞色素P450(CYP)酶的体内功能、调节和毒理学意义。微粒体细胞色素P代谢多种内源和外源化合物，包括药物、环境化学物质和饮食成分。尽管对人类细胞色素P450的研究很重要，但由于人类和实验动物在细胞色素P450功能和调控方面的已知物种差异，由于人类实验的限制，以及缺乏适用于大多数器官系统，特别是肝外组织的基于细胞的模型，很难研究人细胞色素P450的体内功能和调控。因此，我们一直致力于开发新型的转基因和基因敲除小鼠模型，以研究人细胞色素P450的体内功能和调控。表达人类CYP基因的转基因小鼠(所谓的“人源化”小鼠模型)前景看好，但通常受到相对较高水平的内源性小鼠CYP的存在的限制。虽然使用传统的敲除或敲入方法可以一次一个地灭活小鼠的Cyp基因，但许多小鼠Cyp亚家族的Cyp基因的多样性，以及相应的Cyp酶的重叠底物专一性，使得单Cyp基因敲除小鼠模型作为人类CYP转基因小鼠的背景株并不令人满意。这一探索性/发展性项目的具体目标是培育一种新的小鼠品系，其中缺失7号染色体上12个Cyp2基因和9个Cyp2假基因组成的1.4-Mb Cyp2a-2b-2f-2g-2s基因簇。这种小鼠品系将为与表达一个或多个同源人类细胞色素P2基因的转基因小鼠模型杂交提供一个干净(或“更干净”)的背景。Cyp2a-2b-2f-2g-2s基因敲除小鼠的产生将为各种体内研究(包括机械性和翻译性)将这些重要的CyP2基因人源化铺平道路，并将为研究其他人类CYP和非CYP生物转化基因建立一种强大的创新方法，其中许多基因也发生在基因簇中。

DESCRIPTION (provided by applicant): The long-term objective is to determine the in vivo function, regulation, and toxicological implications of human microsomal cytochrome P450 (CYP) enzymes. Microsomal CYPs metabolize a wide variety of endogenous as well as xenobiotic compounds, including drugs, environmental chemicals, and dietary components. While it is important to study human CYPs, because of the known species differences between humans and laboratory animals in CYP function and regulation, the in vivo function and regulation of human CYPs are difficult to study because of limits on human experimentation, and the lack of suitable cell-based models for most organ systems, particularly for extrahepatic tissues. Thus, our focus has been on developing novel transgenic and knockout mouse models for studying the in vivo function and regulation of human CYPs. Transgenic mice expressing human CYP genes (so-called "humanized" mouse models) hold great promise, but are often limited by the presence of relatively high levels of endogenous mouse CYPs. Although mouse Cyp genes can be inactivated, one at a time, using a traditional knockout or knock-in approach, the multiplicity of Cyp genes in many of the mouse Cyp subfamilies, and the overlapping substrate specificity of the corresponding CYP enzymes, make the single-Cyp knockout mouse models unsatisfactory as background strains for human CYP-transgenic mice. The specific aim of this Exploratory/Developmental project is to generate a novel mouse strain in which a 1.4-Mb Cyp2a-2b-2f-2g-2s gene cluster of 12 Cyp2 genes and 9 Cyp2 pseudogenes on chromosome 7 is deleted. This mouse strain will provide a clean (or "cleaner") background for crossing with transgenic mouse models expressing one or more of the orthologous human CYP2 genes. The generation of the Cyp2a-2b-2f-2g-2s knockout mouse will pave the way for "humanizing" these important CYP2 genes for a wide variety of in vivo studies, both mechanistic and translational, and will establish a powerful and innovative approach for studying other human CYP as well as non-CYP biotransformation genes, many of which also occur in gene clusters.