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Luo Q, Liang W, Zhang Z, Zhu Z, Chen Z, Hu J, Yang K, Chi Q, Ding G. Compromised glycolysis contributes to foot process fusion of podocytes in diabetic kidney disease: Role of ornithine catabolism. Metabolism 2022; 134:155245. [PMID: 35780908 DOI: 10.1016/j.metabol.2022.155245] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/16/2022] [Accepted: 06/22/2022] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Compromised glycolysis in podocytes contributes to the initiation of diabetic kidney disease (DKD). Podocyte injury is characterized by cytoskeletal remodeling and foot process fusion. Compromised glycolysis in diabetes likely leads to switch of energy supply in podocyte. However, the underlying mechanism by which disturbed energy supply in podocytes affects the cytoskeletal structure of podocytes remains unclear. METHODS Metabolomic and transcriptomic analyses were performed on the glomeruli of db/db mice to examine the catabolism of glucose, fatty, and amino acids. Ornithine catabolism was targeted in db/db and podocyte-specific pyruvate kinase M2 knockout (PKM2-podoKO) mice. In vitro, expression of ornithine decarboxylase (ODC1) was modulated to investigate the effect of ornithine catabolism on mammalian target of rapamycin (mTOR) signaling and cytoskeletal remodeling in cultured podocytes. RESULTS Multi-omic analyses of the glomeruli revealed that ornithine metabolism was enhanced in db/db mice compared with that in db/m mice under compromised glycolytic conditions. Additionally, ornithine catabolism was exaggerated in podocytes of diabetic PKM2-podoKO mice compared with that in diabetic PKM2flox/flox mice. In vivo, difluoromethylornithine (DFMO, inhibitor of ODC1) administration reduced urinary albumin excretion and alleviated podocyte foot process fusion in db/db mice. In vitro, 2-deoxy-d-glucose (2-DG) exposure induced mTOR signaling activation and cytoskeletal remodeling in podocytes, which was alleviated by ODC1-knockdown. Mechanistically, a small GTPase Ras homolog enriched in the brain (Rheb), a sensor of mTOR signaling, was activated by exposure to putrescine, a metabolic product of ornithine catabolism. CONCLUSION These findings demonstrate that compromised glycolysis in podocytes under diabetic conditions enhances ornithine catabolism. The metabolites of ornithine catabolism contribute to mTOR signaling activation via Rheb and cytoskeletal remodeling in podocytes in DKD.
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Affiliation(s)
- Qiang Luo
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Wei Liang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China.
| | - Zongwei Zhang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Zijing Zhu
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Zhaowei Chen
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Jijia Hu
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Keju Yang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Qingjia Chi
- Department of Mechanics and Engineering Structure, Wuhan University of Technology, China
| | - Guohua Ding
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China.
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