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Abstract: TH-PO789

Involvement of Alpha-Actinin-4 in Focal Adhesion Signaling in Podocytes

Session Information

Category: Glomerular Diseases

  • 1201 Glomerular Diseases: Fibrosis and Extracellular Matrix

Author

  • Lee, Hsiao-Hui, National Yang-Ming University, Taipei, Taiwan
Background

Podocytes are specialized epithelial cells that cover the outer surfaces of glomerular capillaries. They adhere tightly to the glomerular basement membrane and elaborate foot processes to form slit diaphragm for plasma ultrafiltration. Previously, we found that alpha-actinin-4 facilities the recruitment of Shp2 at focal adhesions (FA) that promotes RhoA/ROCK signaling for actomyosin contractility in cells response to matrix rigidity. In this study, we aim to investigate the role of alpha-actinin-4 in controlling cellular tension by focal adhesion signaling in podocytes.

Methods

A mouse temperature-inducible podocyte line was used as a cell model, and the alpha-actinin-4 gene, ACTN4, was knockout by CRISPR/Cas9 method to study its role in the regulation of Shp2 and ROCKII activation.

Results

Differentiated podocytes exhibited matured FAs and stress fibers accompany with hyperactivation of Shp2 and ROCKII that were sensitive to the puromycin aminonucleside-induced podocyte injury. We found that ACTN4 deficiency abolished adhesion-mediated Shp2 and ROCKII activation in podocytes. By Shp2 FRET biosensor, we also demonstrated that alpha-actinin-4 is important for Shp2 activation. Inhibition of Shp2 activity significantly reduced ROCKII activation, FA and stress fiber formation that resulted in protein leakage during filtration.

Conclusion

Our results suggest that alpha-actinin-4 is required for adhesion-mediated Shp2 activation. It facilitates ROCK-mediated actomyosin contractility for strengthening cell adhesion and cytoskeletal architecture those are crucial for podocyte filtration function.

Funding

  • Government Support - Non-U.S.