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Abstract: FR-PO777

Lysosomal Cathepsin B Assists to Withstand Mechanical Stress in Podocytes

Session Information

Category: Glomerular Diseases

  • 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology

Authors

  • Theilig, Franziska, CAU Kiel Institute of Anatomy, Kiel, Germany
  • Westermann, Magdalena, CAU Kiel Institute of Anatomy, Kiel, Germany
  • Kliewe, Felix, University Greifswald Institute of Anatomy and Cell Biology, Greifswald, Germany
  • Saudenova, Makhabbat, CAU Kiel Institute of Anatomy, Kiel, Germany
  • Siebertz, Alexander, CAU Kiel Institute of Anatomy, Kiel, Germany
  • Demir, Fatih, Aarhus University Department of Biomedicine, Aarhus, Denmark
  • Rinschen, Markus M., Aarhus University Department of Biomedicine, Aarhus, Denmark
  • Endlich, Nicole, University Greifswald Institute of Anatomy and Cell Biology, Greifswald, Germany
  • Dahlke, Eileen, CAU Kiel Institute of Anatomy, Kiel, Germany
Background

During filtration podocytes are exposed to mechanical stress and have to buttress the glomerular filter against the filtration pressure. Especially, glomerular hypertension is thought to damage podocytes with concomitant foot process effacement and urinary podocyte loss. Lysosomes are important regulators of cellular physiology and act on cell stress with a lysosomal stress response. Aim of this study was to identify the role of lysosomes and the lysosomal hydrolase cathepsin B (CTSB) in mechanical stress of podocytes.

Methods

Immortalized mouse podocytes and primary podocytes isolated from CTSB -/- and respective control mice were exposed to mechanical stress and examined by immunocytochemistry (ICC) and western blot (WB) analysis. In addition, immortalized mouse podocytes were treated with the CTSB inhibitor CA074Me and morphological alterations were determined. Isolated glomeruli of CTSB -/- and respective control mice were used for proteomic and N-terminomic analysis.

Results

Immortalized podocytes underwent mechanical stress demonstrated an increased expression of lysosomes, lysosomal hydrolases (CTSB, CTSL) and an augmented autophagy (p62, LC3). Inhibiting CTSB in podocytes with mechanical stress revealed lower stress resistance characterized by increased detachment rate and alterations in the number and length of cell processes. N-terminomic analysis of glomeruli from CTSB -/- and control mice showed significant less proteolytic processing of intermediate filaments, actin binding and associated proteins and focal adhesion proteins. WB and ICC analysis of identified proteolytic processed protein confirmed cleavage and demonstrated an altered expression level.

Conclusion

Our data show that mechanical stress in podocytes leads to a lysosomal stress response to increase the expression level of CTSB to induce processing of cytoskeletal associated proteins and adhesion proteins to cope with and withstand higher levels of mechanical stress.

Funding

  • Government Support – Non-U.S.