Cystin, a novel cilia-associated protein, is disrupted in the cpk mouse model of polycystic kidney disease
Xiaoying Hou, … , David R. Beier, Lisa M. Guay-Woodford
Xiaoying Hou, … , David R. Beier, Lisa M. Guay-Woodford
Published February 15, 2002
Citation Information: J Clin Invest. 2002;109(4):533-540. https://doi.org/10.1172/JCI14099.
View: Text | PDF
Article Genetics

Cystin, a novel cilia-associated protein, is disrupted in the cpk mouse model of polycystic kidney disease

Abstract

The congenital polycystic kidney (cpk) mutation is the most extensively characterized mouse model of polycystic kidney disease (PKD). The renal cystic disease is fully expressed in homozygotes and is strikingly similar to human autosomal recessive PKD (ARPKD), whereas genetic background modulates the penetrance of the corresponding defect in the developing biliary tree. We now describe the positional cloning, mutation analysis, and expression of a novel gene that is disrupted in cpk mice. The cpk gene is expressed primarily in the kidney and liver and encodes a hydrophilic, 145–amino acid protein, which we term cystin. When expressed exogenously in polarized renal epithelial cells, cystin is detected in cilia, and its expression overlaps with polaris, another PKD-related protein. We therefore propose that the single epithelial cilium is important in the functional differentiation of polarized epithelia and that ciliary dysfunction underlies the PKD phenotype in cpk mice.

Authors

Xiaoying Hou, Michal Mrug, Bradley K. Yoder, Elliot J. Lefkowitz, Gabriel Kremmidiotis, Peter D’Eustachio, David R. Beier, Lisa M. Guay-Woodford

×

Figure 4

Options: View larger image (or click on image) Download as PowerPoint
Localization of exogenously expressed cystin in stably transfected mCCD ...
Localization of exogenously expressed cystin in stably transfected mCCD cells. To analyze cystin localization, wild-type mCCD cells were transfected with a myc and his epitope–tagged cystin construct. Stable cell cultures were established by selection in Blasticidin. Immunofluorescence analysis was conducted in cells grown on cell culture inserts for a minimum of 3 days after confluence to allow cilial development. (a) Schematic diagram of a principal cell with its primary apical cilium. The two focal planes used in immunofluorescence imaging are indicated. The apical focal plane was used to capture the cilium and the position of the tight junction, indicated by α-ZO-1 staining, and the nuclear focal plane identified the HOECHST-stained nuclei (blue). (b) Immunofluorescence localization of cystin (green) as determined using the anti-his rabbit polyclonal Ab. (c) Cystin (red) localization in the same mCCD cells as shown in b when probed with the anti-myc mAb. (d). Merged image of b and c demonstrated colocalization (yellow) of the myc and his epitope–tagged cystin. (e) In a broad-field view, staining with the anti-his polyclonal Ab (green) indicated that cystin localized to the center of mCCD cells relative to the tight junctions stained for ZO-1 (red). (f and g) Broad-field and representative high-magnification views demonstrated the colocalization of the exogenously expressed cystin (red, anti-myc mAb) and endogenous polaris (green, rabbit polyclonal Ab) in cilia of mCCD cells.