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Abstract: FR-PO327

Functional Coupling of ANXA1 and KCa3.1 Attenuated Renal Tubulointerstitial Fibrosis in Diabetic Kidney Disease

Session Information

Category: Diabetic Kidney Disease

  • 701 Diabetic Kidney Disease: Basic

Authors

  • Wang, Li, Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, State, China
  • Zhu, Bingbing, Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, State, China
  • Liu, Shuang, Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, State, China
  • Xingmei, Yao, Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, State, China
Background

Tubulointerstitial fibrosis (TIF) is the common pathway and major pathological basis for almost all kinds of renal disease including diabetic kidney disease (DKD) progress into chronic kidney disease, thus it is essential to reveal its pathogenesis. Previous research showed that up-regulation of intermediate-conductance Ca2+-activated K+ channel (KCa3.1) contribute to TIF. However, targeting the channel directly have unfortunately side-effect in clinic trials.

Methods

Molecular docking and co-immunoprecipitation were used to detect the binding capability between ANXA1 and KCa3.1. HEK293T and HK-2 cell line were cultured and transfected to confirm whether ANXA1 can be modified by SUMOylation. SUMOylation sites were predicted by SUMOsp2.0, and ANXA1 lysine residues K113, K161, K185, K257 and K312 were mutated to test the relative site change. Biotinylation assay were used to evaluate the ANXA1 activation to KCa3.1 surface expression. Western blot was used for evaluate KCa3.1-mediated TGF-β/Smad signaling activation to detect the expressions of α-SMA, fibronectin, collagen matrix and Smads.

Results

We found that ANXA1, an endogenously generated molecules that promote the physiological resolution of inflammation, could interact with KCa3.1. Mechanistic studies demonstrated that intracellular ANXA1 could be modified by SUMOylation and that SUMOylation primarily occurs at three lysine residues K113, K161, and K257 in hyperglycemia/high glucose stimulation, thereby SUMOylated ANXA1 regulating the membrane transport and lysosomal degradation of KCa3.1 channel protein, and ultimately delaying KCa3.1-mediated TGF-β/Smad activation and TIF progression in DKD state.

Conclusion

Our study suggests that ANXA1-KCa3.1 functional coupling may be a promising therapeutic strategy to mitigate DKD-induced TIF.