Compromised Cytoarchitecture and Polarized Trafficking in Autosomal Dominant Polycystic Kidney Disease Cells

Abstract

Cystogenesis associated with autosomal dominant polycystic kidney disease (ADPKD) is characterized by perturbations in the polarized phenotype and function of cyst-lining epithelial cells. The polycystins, the protein products of the genes mutated in the majority of ADPKD cases, have been described recently, but the pathological mechanism by which causal mutations result in the mislocalization of cell membrane proteins has remained unclear. This report documents the dissociation from the ADPKD cell basolateral membrane of three molecules essential for spatial organization and exocytosis. The adherens junction protein E-cadherin, the subcellular disposition of which governs intercellular and intracellular architecture, was discovered sequestered in an internal ADPKD cell compartment. At the same time, sec6 and sec8, components of a complex critical for basolateral cargo delivery normally arrayed at the apico-lateral apex, were depleted from the ADPKD cell plasma membrane. An analysis of membrane transport revealed that basolateral trafficking of proteins and lipids was impaired as a result of delayed cargo exit from the ADPKD cell Golgi apparatus. Apical transport proceeded normally. Taken together with recent documentation of an association between polycystin-1 and E-cadherin (Huan and van Adelsberg 1999), the data suggest that causal mutations disrupt E-cadherin–dependent cytoarchitecture, adversely affecting protein assemblies crucial for basolateral trafficking.

The Exocyst Affects Protein Synthesis by Acting on the Translocation Machinery of the Endoplasmic Reticulum

“…This link could be significant for human diseases involving changes in protein synthesis and polarity such as autosomal dominant polycystic kidney disease, in which the exocyst has been shown to be misexpressed (34). Further studies are needed to determine the exact mechanism by which the exocyst/Sec61␤ interaction affects protein synthesis.…”

“…Other groups, although not looking at synthesis or secretion, have shown that the exocyst specifically affects basolateral protein delivery to the cell surface (19,33,34). As noted, the fact that all of the major secretory proteins were increased (and by approximately the same degree) made a coordinated transcriptional effect seem unlikely, given the diversity of transcriptional regulation.…”

Human ADPKD primary cyst epithelial cells with a novel, single codon deletion in the PKD1 gene exhibit defective ciliary polycystin localization and loss of flow-induced Ca2+ signaling

“…Cortical tubules were dissected from one freshly harvested cadaveric human kidney not used for transplant and from the grossly normal lower poles of two human kidneys (NK57M03 and NK 11-7-02) resected for renal cell carcinoma. The epithelial cells from both sources were grown in primary culture and passaged as described (4,5 Genomic DNA analysis. Genomic DNA was prepared from NK cells from individual NK57M03 and cyst cells from individual PKD 10/27/98.…”

A polycystin multiprotein complex constitutes a cholesterol-containing signalling microdomain in human kidney epithelia

“…Human primary kidney epithelial cells were derived from previously healthy individuals via the NDRI (National Disease Research Interchange, Philadelphia, PA, U.S.A.) isolated and cultured as described in [20,21]. Primary cystic epithelia were isolated and cultured as described.…”