Kidney Week

Abstract: TH-PO177

Klotho Protects Diabetic Nephropathy via Inhibiting Orai1 and TRPC5/6 Channels in Podocytes

Session Information

• Diabetic Kidney Disease: Basic - I
  November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
  Abstract Time: 10:00 AM - 12:00 PM

Category: Diabetic Kidney Disease

• 601 Diabetic Kidney Disease: Basic

Authors

• Kim, Ji-Hee, Department of Physiology, Yonsei University Wonju College of Medicine, Wonjusi, Korea (the Republic of)

Ji-Hee Kim,

• Dang, Bao Thi Ngoc, Department of Physiology, Yonsei University Wonju College of Medicine, Wonjusi, Korea (the Republic of)

Bao Thi Ngoc Dang,

• Hwang, Kyu-Hee, Department of Physiology, Yonsei University Wonju College of Medicine, Wonjusi, Korea (the Republic of)

Kyu-Hee Hwang,

• Pham, Nghia Thi, Department of Physiology, Yonsei University Wonju College of Medicine, Wonjusi, Korea (the Republic of)

Nghia Thi Pham,

• Eom, Minseob, Department of Pathology, Yonsei University Wonju College of Medicine, Wonjusi, Korea (the Republic of)

Minseob Eom,

• Cha, Seung-Kuy, Department of Physiology, Yonsei University Wonju College of Medicine, Wonjusi, Korea (the Republic of)

Seung-Kuy Cha,

Background

Klotho protein is predominantly produced in the kidney, where it regulates multiple renal ion channels to protect the kidney filter and renal diseases. Podocytes play a vital role in kidney filter function and are primary pathologic target for diabetic nephropathy (DN). Perturbation of Ca²⁺ signaling has been implicated in podocyte dysfunction leading to DN. Here we demonstrated that Klotho ameliorates podocyte injury by stabilizing Orai1 and TRPC5/6 channel-mediated Ca²⁺ signaling to prevent DN.

Methods

Type 2 diabetic db/db mice received i.p. injections of Klotho protein three times a week. The albumin/creatinine ratio, proteins & mRNA levels were analyzed at 11, 15 and 19-week-old db/db mice and db/m was used as a control group. Live-cell imaging and immunocytochemistry were performed in immortalized mouse podocytes.

Results

In a type 2 diabetic db/db mouse model, Klotho and synaptopodin were downregulated, while Orai1, TRPC5, and TRPC6 were overexpressed in early and late periods, respectively. Soluble Klotho suppressed Orai1- and TRPC5/6-mediated Ca²⁺ entry in mouse cultured podocytes via inhibiting growth factors and/or insulin signaling. Mechanistically, soluble Klotho reduced cell surface abundance of Orai1 and TRPC5/6, but not TRPC3 by suppressing phosphoinositide-3-kinase-dependent trafficking of these channels. In addition, soluble Klotho downregulated protein expression of Orai1 and TRPC6 by inhibiting growth factor-driven SGK1 activation. Functionally exaggerated actin remodeling by Orai1 and TRPC6 activation was ameliorated by soluble Klotho. Notably, administration of Klotho protein in db/db mice suppressed phosphorylation of SGK1 and rescued dissolution of synaptopodin and WT-1. Finally, Klotho ameliorated podocyte foot process disruption and proteinuria in db/db mice.

Conclusion

Taken together, our results suggest that Klotho protects proteinuria and podocyte actin cytoskeletal remodeling through stabilizing Ca²⁺ signaling mediated by Orai1 and TRPC5/6, which provides a new potential therapeutic strategy for the treatment of DN.

Funding

• Government Support – Non-U.S.