Kidney Week

Abstract: SA-PO203

Ezrin Plays Important Roles in the Regulation of Foot Process Morphology in the Glomerular Podocytes

Session Information

• Glomerular: Cell Biology
  November 04, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Glomerular

• 1003 Glomerular: Cell Biology

Author

• Hatano, Ryo, Ritsumeikan University, Kusatsu, Japan

Ryo Hatano,

Background

Ezrin is highly expressed in the glomerular podocytes, and is reported to form multi-protein complex with a scaffold protein Na⁺/H⁺ exchanger regulatory factor 2 (NHERF2), and podocalyxin, a major sialoprotein. Podocalyxin deficient mice died within 24 hrs after birth with anuric renal failure, whereas NHERF2 knockout mice did not show apparent renal phenotype. On the other hand, physiological roles of ezrin in glomerular podocytes still remain unclear.

Methods

To investigate the physiological roles of ezrin in the regulation of glomerular podocyte function, ezrin knockdown mice (Vil2^kd/kd) were used in this study. Histological analysis of glomerulus was performed by H&E staining and electron microscopy. Western blotting and immunofluorescent analysis were performed the expression and localization of related proteins in the podocytes. Rho activities were investigated by ELISA-based pull down assay using isolated mouse glomeruli from WT and Vil2^kd/kd mice and glomerula podocyte cell line, E11.

Results

Vil2^kd/kd mice did not exhibit apparent glomerular dysfunction, morphological defects, and disturbance in the localizations of podocalyxin and NHERF2 in podocytes. In Vil2^kd/kd glomeruli, Rac1 activity was significantly decreased in Vil2^kd/kd glomeruli compared to WT glomeruli although RhoA activity was increased. Then, we examined Rho-activities in E11 cells, in which ezrin expression was downregulated by siRNA. Rac1 activity was significantly decreased in ezrin knockdown E11 cells, whereas significant change in the RhoA activity was not observed. On the other hand, transfection of constitutively active ezrin (T567D) increased the activity of Rac1. Furthermore, increased lamellipodia formation was observed in the T567D-transfected E11 cells.

Conclusion

Our results suggest that ezrin regulates the foot process formation via the Rac1 activity in the podocytes. Ezrin is known to interact with Rho-GDP dissociation inhibitor (RhoGDI). Since ezrin promotes the activation of Rho via the striping RhoGDI from GDP-bound Rho, activation of ezrin might be involved with Rac1 activation in the glomerular podocytes.