Kidney Week

Abstract: FR-PO756

Molecular Architecture of the Kidney Slit Diaphragm Revealed by Cryo-electron Tomography

Session Information

• Glomerular Diseases: Mechanisms and Podocyte Biology
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology

Authors

• Birtasu, Alexandra N., Goethe-Universitat Frankfurt am Main, Frankfurt am Main, Hessen, Germany

Alexandra N. Birtasu, MSc

• Wieland, Konstantin, Goethe-Universitat Frankfurt am Main, Frankfurt am Main, Hessen, Germany

Konstantin Wieland, MSc

• Grahammer, Florian, Universitatsklinikum Hamburg-Eppendorf, Hamburg, Hamburg, Germany

Florian Grahammer, MD

• Frangakis, Achilleas, Goethe-Universitat Frankfurt am Main, Frankfurt am Main, Hessen, Germany

Achilleas Frangakis

Background

In this contribution, we will present the molecular architecture of the slit diaphragm (SD), the primary cell-cell junction between podocytes, as imaged by cryo-electron tomography (cryoET) at nanometer resolution. The molecular components of the SD are known from comprehensive mass spectrometry and other studies. Here, we put this information into the context of our cryoET images and depict the SD as an elaborate network of criss-crossing molecules resembling a molecular sieve.

Methods

We isolated mouse glomeruli using the sieving method and vitrified them by high-pressure freezing. Next, we used cryo-focused ion beam milling for specimen thinning, and cryo-electron tomography to visualize the vitreous lamellae obtained from the frozen glomeruli.

Results

Our images show that the SD resembles a fishnet pattern. Fitting of the molecular components provides detailed insights into its structural organization. We construct a blueprint of the SD, describing the complex interaction pattern with multiple contact sites between the molecules Nephrin and Neph1

Conclusion

The SD is a quasi-crystalline, sheet-like molecular polymer that provides the necessary stability and flexibility to compensate for mechanical forces occurring within glomeruli. This advances the understanding of SD biology and holds promise for future studies on structural changes of the SD.