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Abstract: FR-PO962

Tacrolimus Ameliorates Podocyte Injury by Restoring FK506 Binding Protein 12 (FKBP12) at Actin Cytoskeleton in Injured Podocyte

Session Information

Category: Pathology and Lab Medicine

  • 1601 Pathology and Lab Medicine: Basic

Authors

  • Yasuda, Hidenori, Kidney Research Center, Niigata University, Niigata, NIIGATA, Japan
  • Fukusumi, Yoshiyasu, Dept. Cell Biology, Kidney Research Center, Niigata University, Niigata, Japan
  • Zhang, Ying, Niigata University, Japan, Niigata, Japan
  • Kawachi, Hiroshi, Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
Background

FKBP12 was identified as a binding protein of Tacrolimus (Tac). Tac binds to FKBP12 and exhibits immunosuppressive effect through inhibition of calcineurin (CN) activity in T cells. It is reported that Tac treatment directly ameliorates the dysfunction of podocyte by inhibiting the activation of NFAT, a substrate of CN in nephrotic syndrome. We reported that FKBP12 is expressed in glomerular podocyte and the altered expression of FKBP12 is involved in the development of podocyte injury. However, the precise pharmacological mechanism of Tac in podocyte injury was not well understood yet.

Methods

The protein expression of FKBP12 was investigated with western blot and the localization was analyzed with dual label immunostaining in human cultured podocytes. The localization of NFATC3 was also investigated.

Results

FKBP12 was detected both in cytoplasm and along actin cytoskeleton in normal human cultured podocytes. These FKBP12 stainings were decreased in the cultured podocytes treated with Adriamycin (ADR). Tac treatment restored the FKBP12 at actin cytoskeleton. The expression of FKBP12 at the actin cytoskeleton was increased by the Tac treatment to normal cultured podocytes. The western blot analysis showed the protein expression of FKBP12 was decreased in the podocytes with ADR (43.9% to normal, P<0.005). Tac treatment suppressed the decrease (80.5%). The FKBP12 expression of the cells treated with Tac only was 78.7%. NFATC3 staining in nucleus was increased in the podocytes with ADR. Tac treatment partially reduced the nuclear accumulation of NFATC3 in the ADR-treated cells. 27.5% of the cells showed multiple processes with positive actin staining in normal cultured podocytes. The proportion of the cells forming the processes to total cells was decreased in the podocytes treated with ADR (17.5%, P<0.05 vs. normal). Tac treatment suppressed the decrease in ADR (38.1%, P<0.05 vs. no treatment). Tac treatment to normal cells increased the proportion of the cells forming processes (55.7%, P<0.005 vs. normal).

Conclusion

The proper localization of FKBP12 at the actin cytoskeleton participates in the maintenance of process formation. Tac treatment ameliorates podocyte injury by restoring FKBP12 at actin cytoskeleton in injured podocyte.

Funding

  • Government Support - Non-U.S.