Novel transgenic mouse models for human p450 research

描述（由申请方提供）：长期目的是确定人微粒体细胞色素P450（CYP）酶的体内功能、调节和毒理学意义。微粒体CYP代谢多种内源性以及异生质化合物，包括药物、环境化学品和膳食组分。虽然研究人CYP很重要，但由于人和实验室动物在细胞功能和调节方面存在已知的物种差异，由于对人体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）的基于细胞的合适模型，难以研究人CYP的体内功能和调节。因此，我们的重点是开发新的转基因和敲除小鼠模型，用于研究人体CYP的体内功能和调节。表达人CYP基因的转基因小鼠（所谓的“人源化”小鼠模型）具有很大的前景，但通常受到相对高水平的内源性小鼠CYP的存在的限制。虽然小鼠Cyp基因可以被灭活，一次一个，使用传统的敲除或敲入的方法，在许多小鼠Cyp亚家族中的Cyp基因的多样性，和重叠的底物特异性的相应的CYP酶，使单Cyp敲除小鼠模型不能令人满意的背景株的人CYP转基因小鼠。该探索/开发项目的具体目的是产生一种新型小鼠品系，其中7号染色体上的12个Cyp 2基因和9个Cyp 2假基因的1.4 Mb Cyp 2a-2b-2f-2g-2s基因簇缺失。该小鼠品系将为与表达一种或多种直链人CYP 2基因的转基因小鼠模型杂交提供干净（或“更干净”）的背景。Cyp 2a-2b-2f-2g-2s敲除小鼠的产生将为“人源化”这些重要的CYP 2基因铺平道路，用于各种各样的体内研究，包括机制和翻译，并将建立一种强大的和创新的方法来研究其他人源性和非人源性生物转化基因，其中许多也发生在基因簇中。

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.