To Explore and Study Domain Functions of Fibrocystin using Animal Models

描述（由申请人提供）：最近的报道已经证明，纤维囊蛋白/多导管蛋白（FPC）（其突变引起常染色体隐性多囊肾病（ARPKD））可以被切割，并且其细胞外结构域（FPCEXD）通过肾上皮细胞的顶端表面释放到肾小管内腔中（Hogan et al.，2009; Kaimori等人，2007年）。因此，我们假设FPCEXD也可能在肾小管形态发生和/或器官发生中发挥重要作用。缺乏FPCEXD可能导致ARPKD的囊形成。 我们目前已经产生了表达突变体Pkhd 1的小鼠模型（Kim等人，2008）及其转基因（Huang S，2007），并且也从这些模型开发了肾集合细胞系（Hu et al.，2011年）。除了上述模型系统外，我们还产生了一种新的Pkhd 1f 65突变小鼠系，其中FPC的整个单跨膜结构域（FPC-STD）可以通过Cre重组酶的诱导在空间和时间上被floxed出。使用这些模型系统，我们能够确定FPCEXD是否在小鼠胚胎发生或器官发生中起重要作用，以及FPCEXD在发育小鼠中的过表达是否诱导致死表型和囊性表型;异位FPCEXD过表达是否可以挽救我们的Pkhd 1缺陷小鼠中的ARPKD表型;以及FPCEXD功能的暂时恢复是否可以停止或逆转患病肾脏中的囊性表型，从而保留或恢复正常的肾组织。通过研究这些小鼠以及来自它们的细胞系，我们将进一步了解分泌型FPC在胚胎发生、器官发生和囊形成的调控中的作用。这些结果将有助于阐明ARPKD的发病机制，并为ARPKD的治疗干预提供基础。 公共卫生相关性：该提案将使用我们已经/正在生产的新型Pkhd 1小鼠模型来解开Fibrocystin的结构域功能。

DESCRIPTION (provided by applicant): Recent reports have demonstrated that fibrocystin/polyductin (FPC), whose mutations cause autosomal recessive polycystic kidney disease (ARPKD), can be cleaved and its extracellular domain (FPCEXD) is released through the apical surface of renal epithelial cells into the lumen of renal tubules (Hogan et al., 2009; Kaimori et al., 2007). We therefore hypothesize that FPCEXD may also play essential functions in tubulomorphogenesis and/or organogenesis. Lack of FPCEXD may result in cystogenesis of ARPKD. We have currently produced the mouse models expressing mutant Pkhd1 (Kim et al., 2008) and its transgene (Huang S, 2007), and developed renal collecting cell lines from these models as well (Hu et al., 2011). Besides the above model systems, we have also generated a new Pkhd1f65 mutant mouse line in which the entire single transmembrane domain of FPC (FPC-STD) can be spatially and temporally floxed out by induction of Cre recombinase. Using these model systems, we are able to determine whether the FPCEXD plays important functions in mouse embryogenesis or organogenesis, and whether FPCEXD overexpression in the developing mouse induces lethal phenotypes and cystic phenotypes; whether ectopic FPCEXD overexpression can rescue ARPKD phenotypes in our Pkhd1-deficient mice; and whether temporal restoration of FPCEXD function can halt or reverse cystic phenotypes in diseased kidneys, thus preserving or restoring normal renal tissue. By studying these mice as well as the cell lines derived from them, we will gain further insights into the role of secretory FPC in the regulation of embryogenesis, organogenesis, and cystogenesis. These findings will shed light on the pathogenesis of ARPKD and may develop fundamental basis for therapeutic intervention of human ARPKD. PUBLIC HEALTH RELEVANCE: This proposal will use our panel of novel Pkhd1 mouse models, which have been/are being produced, to unravel the domain functions of Fibrocystin.