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Abstract: SA-PO414

Diabetic Kidney Disease: Protein 4.1O Reduces YAP/TAZ Activation and Growth Factor-Induced Podocyte Migration

Session Information

Category: Diabetic Kidney Disease

  • 701 Diabetic Kidney Disease: Basic

Authors

  • Koenigshausen, Eva, Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany
  • Reisewitz, Timo, Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany
  • Duelberg, Nina Maria, Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany
  • Matten, Larissa, Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany
  • Wiech, Thorsten, Genome Biologie Cellulaire et Therapeutique, Paris, Île-de-France, France
  • Sellin, Lorenz, Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany
Background

FRMD3 has been identified as a candidate gene for diabetic nephropathy and encodes for protein 4.1O. So far, four different protein 4.1O splice variants have been identified. The molecular function of these splice variants is unknown.
In diabetic kidney disease growth factor signaling, Yes-associated kinase (YAP, and its paralogue TAZ) translocation into the nucleus and target gene transcription is increased. YAP/TAZ and growth factors have been shown to promote cell migration.

Methods

Human kidney biopsy samples from healthy and diabetic patients were stained for protein 4.1O with immunohistochemistry. HEK293T cells were stimulated with low (5 mmol/l), high (25 mmol/l) glucose concentrations or an osmotic control (5 mmol/l glucose + 19,5 mmol/l mannitol). RNA was isolated and PCR performed. HEK293T cells expressed protein 4.1O splice variants or the control and were stimulated with low, high glucose or mannitol. After cell lysis, western blot was performed for phospho-YAP 397 and actin. Human podocytes were stably transduced with 4.1O splice variants. For migration assays, human podocytes were stimulated with 1 % FCS and different growth factors as well as its inhibitors.

Results

Protein 4.1O expression is detected in healthy human glomeruli by immunohistochemistry. In diabetic patients with CKD stage 3b to 5 and gross proteinuria protein 4.1O expression seems to be increased in podocytes. High glucose but not its osmotic control leads to enhanced transcription of FRMD3. Under high glucose condition protein 4.1O significantly increases YAP phosphorylation. This effect is abrogated if a splice variant lacking a c-terminal domain is expressed. Protein 4.1O reduces podocyte migration after growth factor stimulation compared to control and other splice variants. Treatment with a growth factor inhibitor does not alter podocyte migration in protein 4.1O and control cells.

Conclusion

Expression of protein 4.1O is increased in human diabetic kidney disease and under high glucose conditions. Protein 4.1O splice variants have differential effects on YAP/TAZ activation and growth factor induced migration. This improved understanding of protein 4.1O splice variant function helps to better understand its role in diabetic nephropathy.