The podocyte-specific knockout of palladin in mice with a 129 genetic background affects podocyte morphology and the expression of palladin interacting proteins

PLoS One. 2021 Dec 8;16(12):e0260878. doi: 10.1371/journal.pone.0260878. eCollection 2021.

Abstract

Proper and size selective blood filtration in the kidney depends on an intact morphology of podocyte foot processes. Effacement of interdigitating podocyte foot processes in the glomeruli causes a leaky filtration barrier resulting in proteinuria followed by the development of chronic kidney diseases. Since the function of the filtration barrier is depending on a proper actin cytoskeleton, we studied the role of the important actin-binding protein palladin for podocyte morphology. Podocyte-specific palladin knockout mice on a C57BL/6 genetic background (PodoPalldBL/6-/-) were back crossed to a 129 genetic background (PodoPalld129-/-) which is known to be more sensitive to kidney damage. Then we analyzed the morphological changes of glomeruli and podocytes as well as the expression of the palladin-binding partners Pdlim2, Lasp-1, Amotl1, ezrin and VASP in 6 and 12 months old mice. PodoPalld129-/- mice in 6 and 12 months showed a marked dilatation of the glomerular tuft and a reduced expression of the mesangial marker protein integrin α8 compared to controls of the same age. Furthermore, ultrastructural analysis showed significantly more podocytes with morphological deviations like an enlarged sub-podocyte space and regions with close contact to parietal epithelial cells. Moreover, PodoPalld129-/- of both age showed a severe effacement of podocyte foot processes, a significantly reduced expression of pLasp-1 and Pdlim2, and significantly reduced mRNA expression of Pdlim2 and VASP, three palladin-interacting proteins. Taken together, the results show that palladin is essential for proper podocyte morphology in mice with a 129 background.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • Cytoskeletal Proteins / physiology*
  • Genetic Background*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Kidney / metabolism
  • LIM Domain Proteins / genetics
  • LIM Domain Proteins / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Phosphorylation
  • Podocytes / cytology
  • Podocytes / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Cytoskeletal Proteins
  • Homeodomain Proteins
  • LIM Domain Proteins
  • Lasp1 protein, mouse
  • Microfilament Proteins
  • Pdlim2 protein, mouse
  • palladin protein, mouse

Grants and funding

This work was supported by a grant of the Federal Ministry of Education and Research (BMBF, grant 01GM1518B, STOP- FSGS) to Nicole Endlich. This work was generously supported by the Südmeyer fund for kidney and vascular research (‘Südmeyer Stiftung für Nieren- und Gefäßforschung') and the Dr. Gerhard Büchtemann fund, Hamburg, Germany. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.