ION CHANNEL REGULATION BY THE CYTOPLASMIC TAIL OF PDK1

多囊肾是最常见的遗传性疾病继发于单一基因突变。 PKD-1基因中的杂合子种系突变和随后编码多肽多囊蛋白-1的氨基酸序列的改变与受累队列中的疾病共分离。第二个等位基因的体细胞突变可能是发生或加速囊肿形成所必需的。 囊肿发生与生长控制失调和基质结构改变有关，并被认为需要这种失调。 这些变化伴随着从净重吸收的上皮表型到净分泌的上皮表型的转变。 然而，尽管PKD 1-/-小鼠中人类疾病方面的表型复制，候选多囊蛋白-1结合伴侣的发现，多囊蛋白-1亚结构域过表达产生的细胞信号传导改变的发现，多囊蛋白-1突变导致持续分泌表型伴随囊肿扩大的机制仍然未知。在非洲爪蟾卵母细胞和HEK 293细胞中，多囊蛋白-1的部分C-末端胞质结构域作为融合蛋白CD16.7-PKD-1（115-226）过表达上调阳离子通道活性。 我们推测，扰动这种或类似的功能伴随着正常生殖系多囊蛋白-1等位基因的假定体细胞突变，偶尔肾小管上皮细胞的ADPKD-1杂合子，引起囊肿。 我们进一步假设，这种失调（或失去这种功能）促进或导致从正常表型的净溶质重吸收的净分泌典型的囊肿上皮细胞在ADPKD的过渡。 我们建议将这些研究扩展到极化正常和ADPKD上皮细胞，并研究这种活性的调节。 我们将寻找新的相互作用蛋白，并制备适合结构分析的蛋白。

Polycystic kidney disease is the most common inherited disease secondary to mutation of a single gene. Heterozygous germline mutations in the PKD-1 gene and consequent alterations in the amino acid sequence of the encoded polypeptide, polycystin-1, cosegregate with disease in affected cohorts. Somatic mutations in the second allele may be required for onset of or acceleration of cystogenesis. Cystogenesis is associated with and is thought to require dysregulation of growth control and altered matrix structure. These changes are coupled with conversion from an epithelial phenotype of net reabsorption to one of net secretion. However, despite the phenotypic reproduction of aspects of the human disease in PKD1 -/- mice, the discovery of candidate polycystin-1 binding partners, the discovery of alterations in cell signalling produced by overexpression of a polycystin-1 subdomain, the mechanisms by which polycystin-1 mutations lead to a sustained secretory phenotype accompanied by cyst enlargement remain unknown. Overexpression of part of the C-terminal cytoplasmic domain of polycystin-1 as the fusion protein CD16.7-PKD-1(115-226) upregulates cation channel activity in Xenopus oocytes and in HEK293 cells. We hypothesize that perturbation of this or similar functions accompanies the postulated somatic mutation of the normal germline polycystin-1 allele in the occasional tubular epithelial cells of ADPKD-1 heterozygotes that give rise to cysts. We further hypothesize that this dysregulation (or loss of this function) promotes or causes transition from the normal phenotype of net solute reabsorption to that of net secretion typifying cyst epithelial cells in ADPKD. We propose to extend these studies to polarized normal and ADPKD epithelial cells, and to study regulation of this activity. We will search for novel interacting proteins, and prepare protein suitable for structural analysis.