The University of North Carolina at Chapel Hill School of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, CB# 7248, 6123A Thurston-Bowles Bldg., Chapel Hill, NC 27599-7248, USA.
Am J Respir Cell Mol Biol. 2010 Jul;43(1):55-63. doi: 10.1165/rcmb.2009-0118OC. Epub 2009 Aug 12.
Studies of primary ciliary dyskinesia (PCD) have been hampered by the lack of a suitable animal model because disruption of essential ciliary genes in mice results in a high incidence of lethal hydrocephalus. To develop a viable mouse model for long-term studies of PCD, we have generated a transgenic mouse line in which two conserved exons of the mouse intermediate dynein chain gene, Dnaic1, are flanked by loxP sites (Dnaic1(flox/flox)). Dnaic1 is the murine homolog of human DNAI1, which is mutated in approximately 10% of human PCD cases. These mice have been crossed with mice expressing a tamoxifen-inducible Cre recombinase (CreER). Treatment of adult Dnaic1(flox/flox)/CreER(+/-) mice with tamoxifen results in an almost complete deletion of Dnaic1 with no evidence of hydrocephalus. Treated animals have reduced levels of full-length Dnaic1 mRNA, and electron micrographs of cilia demonstrate a loss of outer dynein arm structures. In treated Dnaic1(flox/flox)/CreER(+/-) animals, mucociliary clearance (MCC) was reduced over time. After approximately 3 months, no MCC was observed in the nasopharynx, whereas in the trachea, MCC was observed for up to 6 months, likely reflecting a difference in the turnover of ciliated cells in these tissues. All treated animals developed severe rhinosinusitis, demonstrating the importance of MCC to the health of the upper airways. However, no evidence of lung disease was observed up to 11 months after Dnaic1 deletion, suggesting that other mechanisms are able to compensate for the lack of MCC in the lower airways of mice. This model will be useful for the study of the pathogenesis and treatment of PCD.
原发性纤毛运动障碍（PCD）的研究受到缺乏合适动物模型的阻碍，因为在小鼠中破坏重要的纤毛基因会导致高比例的致死性脑积水。为了开发一种可行的用于 PCD 长期研究的小鼠模型，我们生成了一种转基因小鼠品系，其中小鼠中间动力蛋白链基因 Dnaic1 的两个保守外显子被loxP 位点包围（Dnaic1(flox/flox)）。Dnaic1 是人类 DNAI1 的小鼠同源物，大约 10%的人类 PCD 病例存在 DNAI1 突变。这些小鼠与表达可诱导 tamoxifen 的 Cre 重组酶（CreER）的小鼠杂交。用 tamoxifen 处理成年 Dnaic1(flox/flox)/CreER(+/-)小鼠可导致 Dnaic1 几乎完全缺失，没有脑积水的证据。经过处理的动物的全长 Dnaic1 mRNA 水平降低，纤毛的电子显微镜照片显示外动力蛋白臂结构缺失。在经过处理的 Dnaic1(flox/flox)/CreER(+/-)动物中，随时间推移，黏液纤毛清除（MCC）减少。大约 3 个月后，在鼻咽部观察不到 MCC，而在气管中，MCC 可观察到长达 6 个月，这可能反映了这些组织中纤毛细胞更新的差异。所有经过处理的动物都发展出严重的鼻旁窦炎，表明 MCC 对上呼吸道健康的重要性。然而，在 Dnaic1 缺失后长达 11 个月，没有观察到肺部疾病的证据，这表明其他机制能够补偿小鼠下呼吸道 MCC 的缺乏。该模型将有助于研究 PCD 的发病机制和治疗方法。
