Abstract: SA-PO213

The Essential Role of Cofilin1 in Podocytes under Diabetic Conditions

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

Authors

  • Teng, Beina, Medical School Hannover, Hannover, Germany
  • Schaefer, Irini, Medical School Hannover, Hannover, Germany
  • Haller, Hermann G., Medical School Hannover, Hannover, Germany
  • Schiffer, Mario, Medical School Hannover, Hannover, Germany
Background

Cofilin1 is known as actin filament severing protein and thus a key regulator of actin dynamics. Its deficiency results in the loss of a precisely organized actin cytoskeletal architecture and can reduce cell migration and motility. In podocytes, Cofilin1 dysregulation leads to loss of secondary foot processes and FP effacement. Cofilin1 is also described as a part of a complex with actin and phosphorylated RNA polymerase (Pol) II, playing a major role in the regulation of gene transcription. In mammalian cells, Cofilin1 is inactivated via phosphorylation and translocated to the nucleus

Methods

To study the role of Cofilin1 in diabetes, sections of Type I diabetic mice induced by STZ, Type II diabetic db/db mice and Type II diabetic patients were evaluated by IF stainings against Cofilin1 and p-Cofilin1. Human and murine podocytes stimulated with glucose or TGF-β were analyzed for Cofilin1, its colocalization with Pol II and the distribution of F-actin. We also analyzed the phosphorylation profile of Cofilin1 at different time points using westernblot. After glucose treatment, migration assays were perfomed to compare the capability of podocytes to migrate into to the scratched wound with or without addition of p-Cofilin1 blocking peptide.

Results

Phosphorylated Cofilin1 is strongly detected in the nucleus of podocytes in diabetic mice and patients. Stimulation of cultured podocytes with glucose or TGF-β induced the translocation of Cofilin1 into the nucleus and led to a dysregulation of actin filaments, and Cofilin1 phosphorylated on Ser3 is mainly localized to the nucleus. Westernblots indicated an increased phosphoylation of Cofilin1 30 minutes after glucose treatment. Comparing the location of p-Cofilin1 with phosphorylated Pol II indicated a redistribution of Pol II away from areas with
p-Cofilin1/actin, which most likely impacts transcriptional elongation. Podocytes remained static after glucose treatment in culture, but their migration ability was restored when p-Cofilin blocking peptide was added.

Conclusion

Localization of p-Cofilin1 to the nucleus is a strong indicator of diabetes induced dysfunction of podocytes; impacting the reorganization of the actin cytoskeleton as well as transcription. The phospho-inhibitor of Cofilin1 is a novel potential candidate to prevent p-Cofilin1 mediated progression of podocyte dysfunction and podocyte damage in diabetes.