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Solanki AK, Arif E, Srivastava P, Furcht CM, Rahman B, Wen P, Singh A, Holzman LB, Fitzgibbon WR, Budisavljevic MN, Lobo GP, Kwon SH, Han Z, Lazzara MJ, Lipschutz JH, Nihalani D. Phosphorylation of slit diaphragm proteins NEPHRIN and NEPH1 upon binding of HGF promotes podocyte repair. J Biol Chem 2021; 297:101079. [PMID: 34391780 PMCID: PMC8429977 DOI: 10.1016/j.jbc.2021.101079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 08/02/2021] [Accepted: 08/11/2021] [Indexed: 12/22/2022] Open
Abstract
Phosphorylation (activation) and dephosphorylation (deactivation) of the slit diaphragm proteins NEPHRIN and NEPH1 are critical for maintaining the kidney epithelial podocyte actin cytoskeleton and, therefore, proper glomerular filtration. However, the mechanisms underlying these events remain largely unknown. Here we show that NEPHRIN and NEPH1 are novel receptor proteins for hepatocyte growth factor (HGF) and can be phosphorylated independently of the mesenchymal epithelial transition receptor in a ligand-dependent fashion through engagement of their extracellular domains by HGF. Furthermore, we demonstrate SH2 domain–containing protein tyrosine phosphatase-2–dependent dephosphorylation of these proteins. To establish HGF as a ligand, purified baculovirus-expressed NEPHRIN and NEPH1 recombinant proteins were used in surface plasma resonance binding experiments. We report high-affinity interactions of NEPHRIN and NEPH1 with HGF, although NEPHRIN binding was 20-fold higher than that of NEPH1. In addition, using molecular modeling we constructed peptides that were used to map specific HGF-binding regions in the extracellular domains of NEPHRIN and NEPH1. Finally, using an in vitro model of cultured podocytes and an ex vivo model of Drosophila nephrocytes, as well as chemically induced injury models, we demonstrated that HGF-induced phosphorylation of NEPHRIN and NEPH1 is centrally involved in podocyte repair. Taken together, this is the first study demonstrating a receptor-based function for NEPHRIN and NEPH1. This has important biological and clinical implications for the repair of injured podocytes and the maintenance of podocyte integrity.
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Affiliation(s)
- Ashish K Solanki
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Ehtesham Arif
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Pankaj Srivastava
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Christopher M Furcht
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Bushra Rahman
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Pei Wen
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Avinash Singh
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Lawrence B Holzman
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wayne R Fitzgibbon
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Milos N Budisavljevic
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Glenn P Lobo
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Sang-Ho Kwon
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, USA
| | - Zhe Han
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Matthew J Lazzara
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Joshua H Lipschutz
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA; Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina, USA.
| | - Deepak Nihalani
- Division of Kidney, Urologic and Hematologic Diseases, National Institutes of Health, Bethesda, Maryland, USA
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