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Kidney Week

Abstract: FR-PO989

Fibrocystin-Deficient MDCKII Cells: Defective Control of Cell Adhesion and Polarity Blocks Epithelial Morphogenesis

Session Information

Category: Genetic Diseases of the Kidney

  • 1001 Genetic Diseases of the Kidney: Cystic

Authors

  • Ziegler, Wolfgang H., Hannover Medical School, Hannover, Germany
  • Soetje, Birga, Hannover Medical School, Hannover, Germany
  • Marten, Lisa P., Hannover Medical School, Hannover, Germany
  • Fenov, Ljupcho, Hannover Medical School, Hannover, Germany
  • Haffner, Dieter, Hannover Medical School, Hannover, Germany
Background

Mutations of the Pkhd1 genecause autosomal recessive polycystic kidney disease (ARPKD). Pkhd1 encodes fibrocystin/polyductin (FPC), a very large, ciliary type I membraneproteinof mostly uncharacterized function, which is suggested to affect adhesion signaling of cells. Contributions of altered epithelial cell interaction to the disease process of ARPKD are not understood. Here, we propose a model wherein inadequate control of cell adhesion and centrosome positioning prevent formation (and homeostasis) of correctly polarized epithelia.

Methods

Based on Pkhd1 silencing, we analyze FPC function in cells with renal collecting duct characteristics, Madin-Darby canine kidney cells (MDCKII). Cells are studied on micro-pattered chips in 3D cell culture conditions allowing analysis of polarity, lumen formation and ciliogenesis in epithelial spheroids. Quantitative automated image processing is applied to analyze z-stacks of 5-color fluorescence images. To determine critical differences in cell adhesion parameters, MDCK cells are studied also on chips in their 1-/2-cell stages. Activation of adhesion signaling is addressed based on phosphorylation of the FAK/Src axis.

Results

Using defined adhesion conditions, we quantified the impact of FPC deficiency on size / density of adhesion sites, cell shape characteristics and initiation of an apical surface. Effects on apicobasal polarity and lumen formation correlate significantly with positioning of centrosomes in 1-/2-cell stages, and activation of adhesion signaling. FPC-deficient cells reveal defects in the formation of correctly polarized epithelial spheroids, which are restored upon transient reduction of actomyosin contractility during the critical early phase of the morphogenesis assay.

Conclusion

Altered adhesion sensing and interaction of FPC-deficient epithelial cells lead to impaired epithelial morphogenesis and by implication homeostasis, which are suggested to lie at the heart of progressive epithelial defects in ARPKD. Closely controlled cell-based models with selective genetic alterations provide the means for a better molecular understanding and furthermore options to test pharmacological correction of epithelial defects.

Funding

  • Private Foundation Support