Abstract: SA-PO332
ARHGEF7 Promotes Stress Fiber Loss in Podocytes by Activation of Rac1
Session Information
- Cellular Crosstalk in Glomerular Diseases - II
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 1903 CKD (Non-Dialysis): Mechanisms
Authors
- Bergwall, Lovisa, University of Gothenburg, Goteborg, Sweden
- Wallentin, Hanna Ilse, AstraZeneca, Gothenburg, Sweden
- Boi, Roberto, University of Gothenburg, Goteborg, Sweden
- Granqvist, Anna, AstraZeneca, Gothenburg, Sweden
- Nystrom, Jenny C., University of Gothenburg, Goteborg, Sweden
- Buvall, Lisa, AstraZeneca, Gothenburg, Sweden
Background
Today it’s known that most kidney diseases are caused by damages to the glomerular filtration barrier, partially by disruption of the actin cytoskeleton in the podocyte. Mutations in several actin regulatory proteins have been identified in patients with renal disease with several of them found to be present in proteins regulating actin cytoskeleton formation. The small RhoGTPase proteins are central in actin cytoskeleton regulation and lately several studies support the detrimental role of activation of the small RhoGTPase Rac1 and its role in stress fiber loss in podocytes.
Methods
In this study we aimed at identifying RhoGTPase regulatory proteins important in actin cytoskeleton loss in podocytes by using phosphoproteomics, lentiviral shRNA knockdown and stressfiber analysis on cultured podocytes, in combination with RNA sequencing of glomeruli from diabetic nephropathy animal models.
Results
By using protamine sulfate, known to cause actin cytoskeleton injury, on cultured podocytes followed by phosphoproteomics and pathway analysis we identified actin cytoskeleton to be the top ranked activated pathway. The guanine nucleotide exchange factor ARHGEF7 was identified to be phosphorylated at Ser 340, a site when phosphorylated known to cause Rac1 activation. Podocytes depleted of ARHGEF7 was protected from stress fiber loss when exposed to protamine sulfate, further confirming the involvement of ARHGEF7 in actin cytoskeleton rearrangement. In combination, RNA sequencing data from two diabetic nephropathy models, BTBR ob/ob and eNOS db/db mice, showed increased levels of ARHGEF7 in isolated glomeruli, indicating increased ARHGEF7 activity in nephrotic syndrome.
Conclusion
These data reviles upregulation of ARHGEF7 in diabetic nephropathy mice models and that ARHGEF7 plays a central role in podocyte actin cytoskeleton regulation, promoting loss of actin cytoskeleton in podocytes by the activation of Rac1.
Funding
- Commercial Support – AstraZeneca