Ion Transport Dysregulation in Cilium-deficient ARPKD

描述（由申请方提供）：两种遗传形式的多囊肾病（PKD）在人或小鼠模型中均表现为肾小管或上皮细胞形态和结构的深刻变化，这是由于至少部分定位于皮质集合管（CCD）主细胞（PC细胞）顶端中央单纤毛的蛋白质突变所致。一旦PKD的遗传和生物化学后果表现为这种形态学变化，细胞或肾小管结构的变化就会深刻影响跨上皮离子转运。在人类常染色体隐性遗传性PKD（ARPKD）单层细胞中，有证据表明钠吸收过度，尽管钠转运机制尚未明确定义。这种异常可以解释在大多数人类ARPKD患者中观察到的早发性高血压。使用由于与Immortomouse的遗传杂交而永生化的小鼠肾上皮细胞，并形成来自野生型、突变型和遗传拯救的PC细胞的极化上皮细胞单层，所述PC细胞来自具有非常高电阻的橡树岭多囊肾（orpk）小鼠CCD，我们的实验室已经收集了初步的数据，显示在小鼠orpk ARPKD突变的皮质集合管（CCD）中吸收性钠转运上调主上皮细胞（PC细胞）生长为极化单层，缺乏顶端中央单纤毛，而对照纤毛感受态PC细胞单层。这些上调的钠电流可能代表ENaC和NHE介导的钠过度吸收。综上所述，文献，我们的合作研究小组的经验，我们目前的初步工作，以及我们的原始申请的审查者的建设性批评，使我们制定了以下工作假设：从ARPKD的小鼠模型，缺乏顶端中央单纤毛CCD上调ENaC和NHE介导的钠吸收和高血压。相关的具体目标源于这一假设，旨在了解ARPKD疾病表型的细胞和分子机制。

DESCRIPTION (provided by applicant): Both genetic forms of polycystic kidney disease (PKD) present in human or mouse models as a profound change in renal tubule or epithelial cell morphology and architecture due to mutations in proteins that localize, at least in part, to the apical central monocilium of the cortical collecting duct (CCD) principal cell (PC cell). Once the genetic and biochemical consequences of PKD are manifested in this change in morphology, the change in cellular or tubular architecture affects transepithelial ion transport profoundly. In human autosomal recessive PKD (ARPKD) monolayers, there is evidence of sodium hyperabsorption, although the sodium transport mechanisms are not yet clearly defined. This abnormality may explain early onset hypertension observed in the majority of human ARPKD patients. Using mouse renal epithelial cells that are immortalized due to genetic cross with the Immortomouse and form polarized epithelial cell monolayers from wild-type, mutant, and genetically rescued PC cells from the Oak Ridge polycystic kidney (orpk) mouse CCD of very high electrical resistance, our laboratory has gathered preliminary data showing upregulated absorptive sodium transport in mouse orpk ARPKD mutant cortical collecting duct (CCD) principal epithelial cells (PC cells) grown as polarized monolayers and lacking apical central monocilia versus control cilium-competent PC cell monolayers. These upregulated sodium currents may represent ENaC- and NHE-mediated sodium hyperabsorption. Taken together, the literature, the experience of our collaborative research group, our current preliminary work, and the constructive criticism of the reviewers of our original application led us to formulate the following working hypothesis: CCDs from mouse models of ARPKD that lack apical central monocilia have upregulated ENaC- and NHE-mediated sodium absorption and resultant hypertension. Interrelated specific aims derive from this hypothesis and are designed to understand the cellular and molecular mechanisms that underlie this ARPKD disease phenotype.