Starremans P G, Li X, Finnerty P E, Guo L, Takakura A, Neilson E G, Zhou J
Department of Medicine, Renal Division, Harvard Institutes of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
Kidney Int. 2008 Jun;73(12):1394-405. doi: 10.1038/ki.2008.111. Epub 2008 Apr 2.
Autosomal dominant polycystic kidney disease, a leading cause of end-stage renal disease in adults, is characterized by progressive focal cyst formation in the kidney. Embryonic lethality of Pkd1-targeted mice limits the use of these mice. Here we developed a floxed allele of Pkd1 exons 2-6. Global deletion mutants developed polyhydramnios, hydrops fetalis, polycystic kidney and pancreatic disease. Somatic Pkd1 inactivation in the kidney was achieved by crossing Pkd1(flox) mice with transgenic mice expressing Cre controlled by a gamma-glutamyltranspeptidase promoter. These mutants developed cysts in both proximal and distal nephron segments and survived for about 4 weeks. Somatic loss of heterozygosity was shown in a reporter mouse strain to cause cystogenesis. Some cysts in young mice are positive for multiple tubular markers and a mesenchymal marker, suggesting a delay in tubular epithelial differentiation. A higher cell proliferation rate was observed in distal nephron segments probably accounting for the faster growth rate of distal cysts. Although we observed an overall increase in apoptosis in cystic kidneys, there was no difference between proximal or distal nephron segments. We also found increased cyclic AMP, aquaporin 2 and vasopressin type 2 receptor mRNA levels, and apical membrane translocation of aquaporin 2 in cystic kidneys, all of which may contribute to the differential cyst growth rate observed. The accelerated polycystic kidney phenotype of these mice provides an excellent model for studying molecular pathways of cystogenesis and to test therapeutic strategies.
常染色体显性多囊肾病是成人终末期肾病的主要病因，其特征是肾脏中逐渐形成局灶性囊肿。靶向Pkd1的小鼠胚胎致死限制了这些小鼠的应用。在此，我们构建了Pkd1外显子2 - 6的floxed等位基因。全身性缺失突变体出现羊水过多、胎儿水肿、多囊肾和胰腺疾病。通过将Pkd1(flox)小鼠与表达由γ-谷氨酰转肽酶启动子控制的Cre的转基因小鼠杂交，实现了肾脏中Pkd1的体细胞失活。这些突变体在近端和远端肾单位节段均出现囊肿，并存活约4周。在一个报告基因小鼠品系中显示体细胞杂合性缺失会导致囊肿形成。幼鼠中的一些囊肿对多种肾小管标志物和一种间充质标志物呈阳性，提示肾小管上皮分化延迟。在远端肾单位节段观察到较高的细胞增殖率，这可能是远端囊肿生长速度较快的原因。虽然我们观察到囊肿性肾脏中凋亡总体增加，但近端或远端肾单位节段之间没有差异。我们还发现囊肿性肾脏中环状AMP、水通道蛋白2和血管升压素2型受体mRNA水平升高，以及水通道蛋白2的顶端膜易位，所有这些可能都导致了观察到的不同囊肿生长速度。这些小鼠加速的多囊肾表型为研究囊肿形成的分子途径和测试治疗策略提供了一个极好的模型。
