Geng L, Burrow C R, Li H P, Wilson P D
Division of Nephrology, Department of Medicine, Mount Sinai School of Medicine, Box 1243, 1 Gustave L. Levy Place, 10029, New York, NY 10029, USA.
Biochim Biophys Acta. 2000 Dec 15;1535(1):21-35. doi: 10.1016/s0925-4439(00)00079-x.
Mutations in the PKD1 gene are responsible for >85% of autosomal dominant polycystic kidney disease (ADPKD). The protein product of PKD1, polycystin-1, is a large, modular membrane protein, with putative ligand-binding motifs in the extracelluar N-terminal portion, 9-11 transmembrane domains and an intracellular C-terminal portion with phosphorylation sites. A role for polycystin-1 as a cell surface receptor involved in cell-matrix and cell-cell interactions has been proposed. In this study, we have analyzed polycystin-1 and associated protein distribution in normal human epithelial cells and examined the role of cell-matrix versus cell-cell interactions in regulation of the assembly of polycystin-1 multiprotein complexes. Immunocytochemistry, sucrose density gradient sedimentation, co-immunoprecipitation analyses and in vitro binding assays have shown that polycystin-1 associates with the focal adhesion proteins talin, vinculin, p130Cas, FAK, alpha-actinin, paxillin and pp60c-src in subconfluent normal human fetal collecting tubule (HFCT) epithelia when cell-matrix interactions predominate. Polycystin-1 also forms higher S value complexes with the cell-cell adherens junction proteins E-cadherin, beta- and gamma-catenins in confluent cultures when cell-cell interactions are predominant. Polycystin-1 multiprotein complexes can be disrupted by cytochalasin D but not by colchicine, suggesting involvement of the actin cytoskeleton. Although inhibition of tyrosine phosphorylation by tyrphostin inhibits polycystin-1-FAK interactions, E-cadherin interactions are enhanced. High calcium treatment also increases polycystin-1-E-cadherin interactions.
PKD1基因的突变是导致超过85%的常染色体显性多囊肾病（ADPKD）的原因。PKD1的蛋白产物多囊蛋白-1是一种大型的模块化膜蛋白，在细胞外N端部分有假定的配体结合基序，9 - 11个跨膜结构域以及一个带有磷酸化位点的细胞内C端部分。有人提出多囊蛋白-1作为一种参与细胞-基质和细胞-细胞相互作用的细胞表面受体发挥作用。在本研究中，我们分析了多囊蛋白-1及相关蛋白在正常人类上皮细胞中的分布，并研究了细胞-基质与细胞-细胞相互作用在多囊蛋白-1多蛋白复合物组装调控中的作用。免疫细胞化学、蔗糖密度梯度沉降、共免疫沉淀分析和体外结合试验表明，在亚汇合的正常人类胎儿集合管（HFCT）上皮细胞中，当细胞-基质相互作用占主导时，多囊蛋白-1与粘着斑蛋白踝蛋白、纽蛋白、p130Cas、粘着斑激酶、α-辅肌动蛋白、桩蛋白和pp60c-src相关联。当细胞-细胞相互作用占主导时，在汇合培养物中，多囊蛋白-1还与细胞-细胞粘着连接蛋白E-钙粘蛋白、β-连环蛋白和γ-连环蛋白形成更高S值的复合物。多囊蛋白-1多蛋白复合物可被细胞松弛素D破坏，但不能被秋水仙碱破坏，提示肌动蛋白细胞骨架参与其中。尽管酪氨酸磷酸化抑制剂 tyrphostin抑制多囊蛋白-1与粘着斑激酶的相互作用，但E-钙粘蛋白的相互作用增强。高钙处理也增加多囊蛋白-1与E-钙粘蛋白的相互作用。
