CFTR and PC2, partners in the primary cilia in autosomal dominant polycystic kidney disease

Abstract

Defects in the primary cilium are associated with autosomal dominant polycystic kidney disease (ADPKD). We used a combination of animal models, western blotting, and confocal microscopy and discovered that CFTR and PC2 are both co-localized to the cilium in normal kidneys, with the levels of both being decreased in cystic epithelia. Cilia were longer in CFTR-null mice and in cystic cells in our ADPKD animal models. We examined septin 2, known to play a role in cilia length, to act as a diffusion barrier and to serve as an enhancer of proliferation. We found that septin 2 protein levels were upregulated and co-localized strongly with CFTR in cystic cells. Application of VX-809, the CFTR corrector, restored CFTR and PC2 toward normal in the cilia, decreased the protein levels of septin 2, and drastically reduced septin 2 co-localization with CFTR. Our data suggest that CFTR is present in the cilia and plays a role there, perhaps through its conductance of Cl-. We also postulate that septin 2 is important for localizing CFTR to the apical membrane in cystic epithelia.

Ultrastructure expansion microscopy (U-ExM) of mouse and human kidneys for analysis of subcellular structures

“…Using the same antibodies (Table 6), we labeled the centrosome-cilium complexes with acetylated α-tubulin and tubular epithelial cells with E-cadherin, in control and ADPKD samples (Figure 7A-B). As expected, cilia in tubular cysts of ADPKD tissue were longer when compared to cilia in nephron tubules of healthy kidneys (Figure 7C-D) (Huang & Lipschutz, 2014; Shao et al, 2020; Yanda et al, 2023). We also noted the presence of excess centrioles in cystic epithelial cells (Figure 7E), as has been previously described in ADPKD (Battini et al, 2008; Burtey et al, 2008; Cheng et al, 2024; Dionne et al, 2018).…”