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Kalyan G, Slusser-Nore A, Dunlevy JR, Bathula CS, Shabb JB, Muhonen W, Somji S, Sens DA, Garrett SH. Protein interactions with metallothionein-3 promote vectorial active transport in human proximal tubular cells. PLoS One 2022; 17:e0267599. [PMID: 35503771 PMCID: PMC9064079 DOI: 10.1371/journal.pone.0267599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 04/11/2022] [Indexed: 02/05/2023] Open
Abstract
Metallothionein 3 (MT-3) is a small, cysteine-rich protein that binds to essential metals required for homeostasis, as well as to heavy metals that have the potential to exert toxic effects on cells. MT-3 is expressed by epithelial cells of the human kidney, including the cells of the proximal tubule. Our laboratory has previously shown that mortal cultures of human proximal tubular (HPT) cells express MT-3 and form domes in the cell monolayer, a morphological feature indicative of vectorial active transport, an essential function of the proximal tubule. However, an immortalized proximal tubular cell line HK-2 lacks the expression of MT-3 and fails to form domes in the monolayer. Transfection of HK-2 cells with the MT-3 gene restores dome formation in these cells suggesting that MT-3 is required for vectorial active transport. In order to determine how MT-3 imparts this essential feature to the proximal tubule, we sought to identify proteins that interact either directly or indirectly with MT-3. Using a combination of pulldowns, co-immunoprecipitations, and mass spectrometry analysis, putative protein interactants were identified and subsequently confirmed by Western analysis and confocal microscopy, following which proteins with direct physical interactions were investigated through molecular docking. Our data shows that MT-3 interacts with myosin-9, aldolase A, enolase 1, β-actin, and tropomyosin 3 and that these interactions are maximized at the periphery of the apical membrane of doming proximal tubule cells. Together these observations reveal that MT-3 interacts with proteins involved in cytoskeletal organization and energy metabolism, and these interactions at the apical membrane support vectorial active transport and cell differentiation in proximal tubule cultures.
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Affiliation(s)
- Gazal Kalyan
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
| | - Andrea Slusser-Nore
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
| | - Jane R. Dunlevy
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
| | - Chandra S. Bathula
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
| | - John B. Shabb
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
| | - Wallace Muhonen
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
| | - Seema Somji
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
| | - Donald A. Sens
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
| | - Scott H. Garrett
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States of America
- * E-mail:
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