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Murali SK, McCormick JA, Fenton RA. Regulation of the water channel aquaporin-2 by cullin E3 ubiquitin ligases. Am J Physiol Renal Physiol 2024; 326:F814-F826. [PMID: 38545647 DOI: 10.1152/ajprenal.00049.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/15/2024] [Accepted: 03/15/2024] [Indexed: 05/04/2024] Open
Abstract
Aquaporin 2 (AQP2) is a vasopressin (VP)-regulated water channel in the renal collecting duct. Phosphorylation and ubiquitylation of AQP2 play an essential role in controlling the cellular abundance of AQP2 and its accumulation on the plasma membrane in response to VP. Cullin-RING ubiquitin ligases (CRLs) are multisubunit E3 ligases involved in ubiquitylation and degradation of their target proteins, eight of which are expressed in the collecting duct. Here, we used an established cell model of the collecting duct (mpkCCD14 cells) to study the role of cullins in modulating AQP2. Western blotting identified Cul-1 to Cul-5 in mpkCCD14 cells. Treatment of cells for 4 h with a pan-cullin inhibitor (MLN4924) decreased AQP2 abundance, prevented a VP-induced reduction in AQP2 Ser261 phosphorylation, and attenuated VP-induced plasma membrane accumulation of AQP2 relative to the vehicle. AQP2 ubiquitylation levels were significantly higher after MLN4924 treatment compared with controls, and they remained higher despite VP treatment. Cullin inhibition increased ERK1/2 activity, a kinase that regulates AQP2 Ser261 phosphorylation, and VP-induced reductions in ERK1/2 phosphorylation were absent during MLN4924 treatment. Furthermore, the greater Ser261 phosphorylation and reduction in AQP2 abundance during MLN4924 treatment were attenuated during ERK1/2 inhibition. MLN4924 increased intracellular calcium levels via calcium release-activated calcium channels, inhibition of which abolished MLN4924 effects on Ser261 phosphorylation and AQP2 abundance. In conclusion, CRLs play a vital role in mediating some of the effects of VP to increase AQP2 plasma membrane accumulation and AQP2 abundance. Whether modulation of cullin activity can contribute to body water homeostasis requires further studies.NEW & NOTEWORTHY Aquaporin 2 (AQP2) is essential for body water homeostasis and is regulated by the antidiuretic hormone vasopressin. The posttranslational modification ubiquitylation is a key regulator of AQP2 abundance and plasma membrane localization. Here we demonstrate that cullin-RING E3 ligases play a vital role in mediating some of the effects of vasopressin to increase AQP2 abundance and plasma membrane accumulation. The results suggest that manipulating cullin activity could be a novel strategy to alter kidney water handling.
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Affiliation(s)
- Sathish K Murali
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - James A McCormick
- Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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2
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Hsieh CH, Chou CC, Fang YC, Hsu PH, Chiu YH, Yang CS, Jow GM, Tang CY, Jeng CJ. 14-3-3 proteins regulate cullin 7-mediated Eag1 degradation. Cell Biosci 2023; 13:18. [PMID: 36717938 PMCID: PMC9885684 DOI: 10.1186/s13578-023-00969-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Mutations in the human gene encoding the neuron-specific Eag1 (KV10.1; KCNH1) potassium channel are linked to congenital neurodevelopmental diseases. Disease-causing mutant Eag1 channels manifest aberrant gating function and defective protein homeostasis. Both the E3 ubiquitin ligase cullin 7 (Cul7) and the small acid protein 14-3-3 serve as binding partners of Eag1. Cul7 mediates proteasomal and lysosomal degradation of Eag1 protein, whereas over-expression of 14-3-3 notably reduces Eag1 channel activity. It remains unclear whether 14-3-3 may also contribute to Eag1 protein homeostasis. RESULTS In human cell line and native rat neurons, disruptions of endogenous 14-3-3 function with the peptide inhibitor difopein or specific RNA interference up-regulated Eag1 protein level in a transcription-independent manner. Difopein hindered Eag1 protein ubiquitination at the endoplasmic reticulum and the plasma membrane, effectively promoting the stability of both immature and mature Eag1 proteins. Suppression of endogenous 14-3-3 function also reduced excitotoxicity-associated Eag1 degradation in neurons. Difopein diminished Cul7-mediated Eag1 degradation, and Cul7 knock-down abolished the effect of difopein on Eag1. Inhibition of endogenous 14-3-3 function substantially perturbed the interaction of Eag1 with Cul7. Further structural analyses suggested that the intracellular Per-Arnt-Sim (PAS) domain and cyclic nucleotide-binding homology domain (CNBHD) of Eag1 are essential for the regulatory effect of 14-3-3 proteins. Significantly, suppression of endogenous 14-3-3 function reduced Cul7-mediated degradation of disease-associated Eag1 mutant proteins. CONCLUSION Overall these results highlight a chaperone-like role of endogenous 14-3-3 proteins in regulating Eag1 protein homeostasis, as well as a therapeutic potential of 14-3-3 modulators in correcting defective protein expression of disease-causing Eag1 mutants.
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Affiliation(s)
- Chang-Heng Hsieh
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Chia-Cheng Chou
- grid.36020.370000 0000 8889 3720National Laboratory Animal Center, National Applied Research Laboratories, Taipei, Taiwan
| | - Ya-Ching Fang
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Po-Hao Hsu
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Yi-Hung Chiu
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Chi-Sheng Yang
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Guey-Mei Jow
- grid.256105.50000 0004 1937 1063School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan
| | - Chih-Yung Tang
- grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Chung-Jiuan Jeng
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.260539.b0000 0001 2059 7017Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
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3
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Yang CR, Park E, Chen L, Datta A, Chou CL, Knepper MA. Proteomics and AQP2 regulation. J Physiol 2022:10.1113/JP283899. [PMID: 36571566 PMCID: PMC10686537 DOI: 10.1113/jp283899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/21/2022] [Indexed: 12/27/2022] Open
Abstract
The advent of modern quantitative protein mass spectrometry techniques around the turn of the 21st century has contributed to a revolution in biology referred to as 'systems biology'. These methods allow identification and quantification of thousands of proteins in a biological specimen, as well as detection and quantification of post-translational protein modifications including phosphorylation. Here, we discuss these methodologies and show how they can be applied to understand the effects of the peptide hormone vasopressin to regulate the molecular water channel aquaporin-2. The emerging picture provides a detailed framework for understanding the molecular mechanisms involved in water balance disorders.
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Affiliation(s)
- Chin-Rang Yang
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
| | - Euijung Park
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
| | - Lihe Chen
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
| | - Arnab Datta
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
- Division of Neuroscience, Yenepoya Research Center, Yenepoya (Deemed to be University), Mangalore, India
| | - Chung-Lin Chou
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
| | - Mark A. Knepper
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
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4
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Insight into the Mammalian Aquaporin Interactome. Int J Mol Sci 2022; 23:ijms23179615. [PMID: 36077012 PMCID: PMC9456110 DOI: 10.3390/ijms23179615] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/16/2022] [Accepted: 08/22/2022] [Indexed: 01/07/2023] Open
Abstract
Aquaporins (AQPs) are a family of transmembrane water channels expressed in all living organisms. AQPs facilitate osmotically driven water flux across biological membranes and, in some cases, the movement of small molecules (such as glycerol, urea, CO2, NH3, H2O2). Protein-protein interactions play essential roles in protein regulation and function. This review provides a comprehensive overview of the current knowledge of the AQP interactomes and addresses the molecular basis and functional significance of these protein-protein interactions in health and diseases. Targeting AQP interactomes may offer new therapeutic avenues as targeting individual AQPs remains challenging despite intense efforts.
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5
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Olesen ETB, Fenton RA. Aquaporin 2 regulation: implications for water balance and polycystic kidney diseases. Nat Rev Nephrol 2021; 17:765-781. [PMID: 34211154 DOI: 10.1038/s41581-021-00447-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2021] [Indexed: 02/06/2023]
Abstract
Targeting the collecting duct water channel aquaporin 2 (AQP2) to the plasma membrane is essential for the maintenance of mammalian water homeostasis. The vasopressin V2 receptor (V2R), which is a GS protein-coupled receptor that increases intracellular cAMP levels, has a major role in this targeting process. Although a rise in cAMP levels and activation of protein kinase A are involved in facilitating the actions of V2R, studies in knockout mice and cell models have suggested that cAMP signalling pathways are not an absolute requirement for V2R-mediated AQP2 trafficking to the plasma membrane. In addition, although AQP2 phosphorylation is a known prerequisite for V2R-mediated plasma membrane targeting, none of the known AQP2 phosphorylation events appears to be rate-limiting in this process, which suggests the involvement of other factors; cytoskeletal remodelling has also been implicated. Notably, several regulatory processes and signalling pathways involved in AQP2 trafficking also have a role in the pathophysiology of autosomal dominant polycystic kidney disease, although the role of AQP2 in cyst progression is unknown. Here, we highlight advances in the field of AQP2 regulation that might be exploited for the treatment of water balance disorders and provide a rationale for targeting these pathways in autosomal dominant polycystic kidney disease.
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Affiliation(s)
- Emma T B Olesen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. .,Department of Endocrinology and Nephrology, North Zealand Hospital, Hillerød, Denmark.
| | - Robert A Fenton
- Department of Biomedicine, Faculty of Health, Aarhus University, Aarhus, Denmark.
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6
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Thomsen ML, Grønkjær C, Iervolino A, Rej S, Trepiccione F, Christensen BM. Atorvastatin does not ameliorate nephrogenic diabetes insipidus induced by lithium or potassium depletion in mice. Physiol Rep 2021; 9:e15111. [PMID: 34762363 PMCID: PMC8582289 DOI: 10.14814/phy2.15111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/15/2021] [Accepted: 10/15/2021] [Indexed: 11/30/2022] Open
Abstract
Acquired forms of nephrogenic diabetes insipidus (NDI) include lithium (Li)-induced and hypokalemia-induced NDI. Both forms are associated with AQP2 downregulation and collecting duct (CD) cellular remodeling. Statins are cholesterol-lowering drugs appearing to increase AQP2 membrane-translocation and improve urine concentration in other NDI models. We have investigated if statins are able to prevent or rescue the Li-induced changes in mice and in a mouse cortical CD cell line (mCCDc1l ). Biotinylation assays showed that acute (1hr) atorvastatin, simvastatin, or fluvastatin increased AQP2 membrane accumulation in mCCDc1l cells showing that the cell line responds to acute statin treatment. To see whether chronic statin treatment abolish the Li effects, mCCDc1l cells were treated with 48 h Li, combined Li/atorvastatin or combined Li/simvastatin. Li reduced AQP2, but combined Li/atorvastatin or Li/simvastatin did not prevent AQP2 downregulation. In mice, chronic (21 days) Li increased urine output and reduced urine osmolality, but combined Li/atorvastatin did not prevent these effects. In inner medulla (IM), Li reduced total AQP2 and increased pS261-AQP2. Combined Li/atorvastatin did not abolish these changes. Atorvastatin did not prevent a Li-induced increase in intercalated cells and proliferation in IM. In mice with already established NDI, atorvastatin had no effect on the Li-induced changes either. Mice subjected to 14 days of potassium-deficient diet developed polyuria and AQP2 downregulation in IM. Co-treatment with atorvastatin did not prevent this. In conclusion, atorvastatin does not appear to be able to prevent or rescue Li-NDI or to prevent hypokalemic-induced NDI.
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Affiliation(s)
| | | | - Anna Iervolino
- Department of Translational Medical SciencesUniversity of Campania “L. Vanvitelli”NaplesItaly
- Biogem Institute of Molecular Biology and GeneticsAriano IrpinoItaly
| | - Soham Rej
- Jewish General Hospital/Lady Davis Institute/Department of PsychiatryMcGill UniversityMontrealQuebecCanada
| | - Francesco Trepiccione
- Department of Translational Medical SciencesUniversity of Campania “L. Vanvitelli”NaplesItaly
- Biogem Institute of Molecular Biology and GeneticsAriano IrpinoItaly
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7
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Petrillo F, Iervolino A, Angrisano T, Jelen S, Costanzo V, D’Acierno M, Cheng L, Wu Q, Guerriero I, Mazzarella MC, De Falco A, D’Angelo F, Ceccarelli M, Caraglia M, Capasso G, Fenton RA, Trepiccione F. Dysregulation of Principal Cell miRNAs Facilitates Epigenetic Regulation of AQP2 and Results in Nephrogenic Diabetes Insipidus. J Am Soc Nephrol 2021; 32:1339-1354. [PMID: 33727367 PMCID: PMC8259636 DOI: 10.1681/asn.2020010031] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/02/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND MicroRNAs (miRNAs), formed by cleavage of pre-microRNA by the endoribonuclease Dicer, are critical modulators of cell function by post-transcriptionally regulating gene expression. METHODS Selective ablation of Dicer in AQP2-expressing cells (DicerAQP2Cre+ mice) was used to investigate the role of miRNAs in the kidney collecting duct of mice. RESULTS The mice had severe polyuria and nephrogenic diabetes insipidus, potentially due to greatly reduced AQP2 and AQP4 levels. Although epithelial sodium channel levels were decreased in cortex and increased in inner medulla, amiloride-sensitive sodium reabsorption was equivalent in DicerAQP2Cre+ mice and controls. Small-RNA sequencing and proteomic analysis revealed 31 and 178 significantly regulated miRNAs and proteins, respectively. Integrated bioinformatic analysis of the miRNAome and proteome suggested alterations in the epigenetic machinery and various transcription factors regulating AQP2 expression in DicerAQP2Cre+ mice. The expression profile and function of three miRNAs (miR-7688-5p, miR-8114, and miR-409-3p) whose predicted targets were involved in epigenetic control (Phf2, Kdm5c, and Kdm4a) or transcriptional regulation (GATA3, GATA2, and ELF3) of AQP2 were validated. Luciferase assays could not demonstrate direct interaction of AQP2 or the three potential transcription factors with miR-7688-5p, miR-8114, and miR-409-3p. However, transfection of respective miRNA mimics reduced AQP2 expression. Chromatin immunoprecipitation assays demonstrated decreased Phf2 and significantly increased Kdm5c interactions at the Aqp2 gene promoter in DicerAQP2Cre+ mice, resulting in decreased RNA Pol II association. CONCLUSIONS Novel evidence indicates miRNA-mediated epigenetic regulation of AQP2 expression.
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Affiliation(s)
- Federica Petrillo
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy,Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Anna Iervolino
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy
| | - Tiziana Angrisano
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Sabina Jelen
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy
| | - Vincenzo Costanzo
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy
| | | | - Lei Cheng
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Qi Wu
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Ilaria Guerriero
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy
| | | | - Alfonso De Falco
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy
| | - Fulvio D’Angelo
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy
| | - Michele Ceccarelli
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy,Department of Electrical Engineering and Information Technology (DIETI) University of Naples “Federico II”, Naples, Italy
| | - Michele Caraglia
- Department of Precision Medicine, University of Campania Luigi Vanvitelli, Naples, Italy
| | - Giovambattista Capasso
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy,Department of Translational Medical Sciences, University of Campania Luigi Vanvitelli, Naples, Italy
| | | | - Francesco Trepiccione
- Biogem, Institute of Genetic Research “Gaetano Salvatore”, Ariano Irpino, Italy,Department of Translational Medical Sciences, University of Campania Luigi Vanvitelli, Naples, Italy
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8
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Sade N, Weng F, Tajima H, Zeron Y, Zhang L, Rubio Wilhelmi MDM, Day G, Peleg Z, Blumwald E. A Cytoplasmic Receptor-like Kinase Contributes to Salinity Tolerance. PLANTS (BASEL, SWITZERLAND) 2020; 9:plants9101383. [PMID: 33080797 PMCID: PMC7650656 DOI: 10.3390/plants9101383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/12/2020] [Accepted: 10/15/2020] [Indexed: 05/14/2023]
Abstract
Receptor-like cytoplasmic kinases (RLCKs) are receptor kinases that lack extracellular ligand-binding domains and have emerged as a major class of signaling proteins that regulate plant cellular activities in response to biotic/abiotic stresses and endogenous extracellular signaling molecules. We have identified a rice RLCK (OsRLCK311) that was significantly higher in transgenic pSARK-IPT rice (Oryza sativa) that exhibited enhanced growth under saline conditions. Overexpression of OsRLCK311 full-length protein (RLCK311FL) and the C-terminus of OsRLCK311 (ΔN) in Arabidopsis confirmed its role in salinity tolerance, both in seedlings and mature plants. Protein interaction assays indicated that OsRLCK311 and ΔN interacted in-vivo with the plasma membrane AQP AtPIP2;1. The RLCK311-PIP2;1 binding led to alterations in the stomata response to ABA, which was characterized by more open stomata of transgenic plants. Moreover, OsRLCK311-ΔN effect in mediating enhanced plant growth under saline conditions was also observed in the perennial grass Brachypodium sylvaticum, confirming its role in both dicots and monocots species. Lastly, OsRLCK311 interacted with the rice OsPIP2;1. We suggest that the rice OsRLCK311 play a role in regulating the plant growth response under saline conditions via the regulation of the stomata response to stress. This role seems to be independent of the RLCK311 kinase activity, since the overexpression of the RLCK311 C-terminus (ΔN), which lacks the kinase full domain, has a similar phenotype to RLCK311FL.
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Affiliation(s)
- Nir Sade
- Department of Plant Sciences, University of California, Davis, CA 95616, USA; (F.W.); (H.T.); (L.Z.); (M.d.M.R.W.); (G.D.)
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel;
- Correspondence: (N.S.); (E.B.)
| | - Fei Weng
- Department of Plant Sciences, University of California, Davis, CA 95616, USA; (F.W.); (H.T.); (L.Z.); (M.d.M.R.W.); (G.D.)
- Suzhou Polytechnic Institute of Agriculture, Suzhou 215008, Jiangsu, China
| | - Hiromi Tajima
- Department of Plant Sciences, University of California, Davis, CA 95616, USA; (F.W.); (H.T.); (L.Z.); (M.d.M.R.W.); (G.D.)
| | - Yarden Zeron
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel;
| | - Lei Zhang
- Department of Plant Sciences, University of California, Davis, CA 95616, USA; (F.W.); (H.T.); (L.Z.); (M.d.M.R.W.); (G.D.)
| | - Maria del Mar Rubio Wilhelmi
- Department of Plant Sciences, University of California, Davis, CA 95616, USA; (F.W.); (H.T.); (L.Z.); (M.d.M.R.W.); (G.D.)
| | - George Day
- Department of Plant Sciences, University of California, Davis, CA 95616, USA; (F.W.); (H.T.); (L.Z.); (M.d.M.R.W.); (G.D.)
| | - Zvi Peleg
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel;
| | - Eduardo Blumwald
- Department of Plant Sciences, University of California, Davis, CA 95616, USA; (F.W.); (H.T.); (L.Z.); (M.d.M.R.W.); (G.D.)
- Correspondence: (N.S.); (E.B.)
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9
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AQP2: Mutations Associated with Congenital Nephrogenic Diabetes Insipidus and Regulation by Post-Translational Modifications and Protein-Protein Interactions. Cells 2020; 9:cells9102172. [PMID: 32993088 PMCID: PMC7599609 DOI: 10.3390/cells9102172] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 09/22/2020] [Accepted: 09/25/2020] [Indexed: 02/07/2023] Open
Abstract
, the molecular defects in the AVPR2 and AQP2 mutants, post-translational modifications (i.e., phosphorylation, ubiquitination, and glycosylation) and various protein-protein interactions that regulate phosphorylation, ubiquitination, tetramerization, trafficking, stability, and degradation of AQP2.
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10
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Basu D, Shoots JM, Haswell ES. Interactions between the N- and C-termini of the mechanosensitive ion channel AtMSL10 are consistent with a three-step mechanism for activation. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:4020-4032. [PMID: 32280992 DOI: 10.1093/jxb/eraa192] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
Although a growing number of mechanosensitive ion channels are being identified in plant systems, the molecular mechanisms by which they function are still under investigation. Overexpression of the mechanosensitive ion channel MSL (MscS-Like)10 fused to green fluorescent protein (GFP) triggers a number of developmental and cellular phenotypes including the induction of cell death, and this function is influenced by seven phosphorylation sites in its soluble N-terminus. Here, we show that these and other phenotypes required neither overexpression nor a tag, and could also be induced by a previously identified point mutation in the soluble C-terminus (S640L). The promotion of cell death and hyperaccumulation of H2O2 in 35S:MSL10S640L-GFP overexpression lines was suppressed by N-terminal phosphomimetic substitutions, and the soluble N- and C-terminal domains of MSL10 physically interacted. We propose a three-step model by which tension-induced conformational changes in the C-terminus could be transmitted to the N-terminus, leading to its dephosphorylation and the induction of adaptive responses. Taken together, this work expands our understanding of the molecular mechanisms of mechanotransduction in plants.
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Affiliation(s)
- Debarati Basu
- NSF Center for Engineering Mechanobiology, Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Jennette M Shoots
- NSF Center for Engineering Mechanobiology, Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
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11
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Fenton RA, Murali SK, Moeller HB. Advances in aquaporin-2 trafficking mechanisms and their implications for treatment of water balance disorders. Am J Physiol Cell Physiol 2020; 319:C1-C10. [PMID: 32432927 DOI: 10.1152/ajpcell.00150.2020] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In mammals, conservation of body water is critical for survival and is dependent on the kidneys' ability to minimize water loss in the urine during periods of water deprivation. The collecting duct water channel aquaporin-2 (AQP2) plays an essential role in this homeostatic response by facilitating water reabsorption along osmotic gradients. The ability to increase the levels of AQP2 in the apical plasma membrane following an increase in plasma osmolality is a rate-limiting step in water reabsorption, a process that is tightly regulated by the antidiuretic hormone arginine vasopressin (AVP). In this review, the focus is on the role of the carboxyl-terminus of AQP2 as a key regulatory point for AQP2 trafficking. We provide an overview of AQP2 structure, disease-causing mutations in the AQP2 carboxyl-terminus, the role of posttranslational modifications such as phosphorylation and ubiquitylation in the tail domain, and their implications for balanced trafficking of AQP2. Finally, we discuss how various modifications of the AQP2 tail facilitate selective protein-protein interactions that modulate the AQP2 trafficking mechanism.
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Affiliation(s)
- Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Hanne B Moeller
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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12
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Saglar Ozer E, Moeller HB, Karaduman T, Fenton RA, Mergen H. Molecular characterization of an aquaporin-2 mutation causing a severe form of nephrogenic diabetes insipidus. Cell Mol Life Sci 2020; 77:953-962. [PMID: 31302751 PMCID: PMC11104860 DOI: 10.1007/s00018-019-03219-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 07/01/2019] [Accepted: 07/05/2019] [Indexed: 01/01/2023]
Abstract
The water channel aquaporin 2 (AQP2) is responsible for water reabsorption by kidney collecting duct cells. A substitution of amino acid leucine 137 to proline in AQP2 (AQP2-L137P) causes Nephrogenic Diabetes Insipidus (NDI). This study aimed to determine the cell biological consequences of this mutation on AQP2 function. Studies were performed in HEK293 and MDCK type I cells, transfected with wildtype (WT) AQP2 or an AQP2-L137P mutant. AQP2-L137P was predominantly detected as a high-mannose form of AQP2, whereas AQP2-WT was observed in both non-glycosylated and complex glycosylated forms. In contrast to AQP2-WT, the AQP2-L137P mutant did not accumulate on the apical plasma membrane following stimulation with forskolin. Ubiquitylation of AQP2-L137P was different from AQP2-WT, with predominance of non-distinct protein bands at various molecular weights. The AQP2-L137P mutant displayed reduced half-life compared to AQP2-WT. Treatment of cells with chloroquine increased abundance of AQP2-WT, but not AQP2-L137P. In contrast, treatment with MG132 increased abundance of AQP2-L137P but not AQP2-WT. Xenopus oocytes injected with AQP2-WT had increased osmotic water permeability when compared to AQP2-L137P, which correlated with lack of the mutant form in the plasma membrane. From the localization of the mutation and nature of the substitution it is likely that AQP2-L137P causes protein misfolding, which may be responsible for the observed functional defects. The data suggest that the L137P mutation results in altered AQP2 protein maturation, increased AQP2 degradation via the proteasomal pathway and limited plasma membrane expression. These combined mechanisms are likely responsible for the phenotype observed in this class of NDI patients.
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Affiliation(s)
- Emel Saglar Ozer
- Department of Biology, Faculty of Science, Hacettepe University, 06800, Ankara, Turkey.
| | - Hanne B Moeller
- Department of Biomedicine, Aarhus University, South, Bldg 1233, 3 Wilhelm Meyers Alle, 8000, Aarhus, Denmark.
| | - Tugce Karaduman
- Department of Biology, Faculty of Science, Hacettepe University, 06800, Ankara, Turkey
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, South, Bldg 1233, 3 Wilhelm Meyers Alle, 8000, Aarhus, Denmark
| | - Hatice Mergen
- Department of Biology, Faculty of Science, Hacettepe University, 06800, Ankara, Turkey
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13
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Probst S, Scharner B, McErlean R, Lee WK, Thévenod F. Inverse Regulation of Lipocalin-2/24p3 Receptor/SLC22A17 and Lipocalin-2 Expression by Tonicity, NFAT5/TonEBP and Arginine Vasopressin in Mouse Cortical Collecting Duct Cells mCCD(cl.1): Implications for Osmotolerance. Int J Mol Sci 2019; 20:ijms20215398. [PMID: 31671521 PMCID: PMC6862280 DOI: 10.3390/ijms20215398] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/12/2019] [Accepted: 10/22/2019] [Indexed: 12/23/2022] Open
Abstract
The rodent collecting duct (CD) expresses a 24p3/NGAL/lipocalin-2 (LCN2) receptor (SLC22A17) apically, possibly to mediate high-affinity reabsorption of filtered proteins by endocytosis, although its functions remain uncertain. Recently, we showed that hyperosmolarity/-tonicity upregulates SLC22A17 in cultured mouse inner-medullary CD cells, whereas activation of toll-like receptor 4 (TLR4), via bacterial lipopolysaccharides (LPS), downregulates SLC22A17. This is similar to the upregulation of Aqp2 by hyperosmolarity/-tonicity and arginine vasopressin (AVP), and downregulation by TLR4 signaling, which occur via the transcription factors NFAT5 (TonEBP or OREBP), cAMP-responsive element binding protein (CREB), and nuclear factor-kappa B, respectively. The aim of the study was to determine the effects of osmolarity/tonicity and AVP, and their associated signaling pathways, on the expression of SLC22A17 and its ligand, LCN2, in the mouse (m) cortical collecting duct cell line mCCD(cl.1). Normosmolarity/-tonicity corresponded to 300 mosmol/L, whereas the addition of 50–100 mmol/L NaCl for up to 72 h induced hyperosmolarity/-tonicity (400–500 mosmol/L). RT-PCR, qPCR, immunoblotting and immunofluorescence microscopy detected Slc22a17/SLC22A17 and Lcn2/LCN2 expression. RNAi silenced Nfat5, and the pharmacological agent 666-15 blocked CREB. Activation of TLR4 was induced with LPS. Similar to Aqp2, hyperosmotic/-tonic media and AVP upregulated Slc22a17/SLC22A17, via activation of NFAT5 and CREB, respectively, and LPS/TLR4 signaling downregulated Slc22a17/SLC22A17. Conversely, though NFAT5 mediated the hyperosmolarity/-tonicity induced downregulation of Lcn2/LCN2 expression, AVP reduced Lcn2/LCN2 expression and predominantly apical LCN2 secretion, evoked by LPS, through a posttranslational mode of action that was independent of CREB signaling. In conclusion, the hyperosmotic/-tonic upregulation of SLC22A17 in mCCD(cl.1) cells, via NFAT5, and by AVP, via CREB, suggests that SLC22A17 contributes to adaptive osmotolerance, whereas LCN2 downregulation could counteract increased proliferation and permanent damage of osmotically stressed cells.
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Affiliation(s)
- Stephanie Probst
- Department of Physiology, Pathophysiology & Toxicology and ZBAF (Centre for Biomedical Education and Research), Faculty of Health, School of Medicine, Witten/Herdecke University, Stockumer Str 12 (Thyssenhaus), D-58453 Witten, Germany.
| | - Bettina Scharner
- Department of Physiology, Pathophysiology & Toxicology and ZBAF (Centre for Biomedical Education and Research), Faculty of Health, School of Medicine, Witten/Herdecke University, Stockumer Str 12 (Thyssenhaus), D-58453 Witten, Germany.
| | - Ruairi McErlean
- Department of Physiology, Pathophysiology & Toxicology and ZBAF (Centre for Biomedical Education and Research), Faculty of Health, School of Medicine, Witten/Herdecke University, Stockumer Str 12 (Thyssenhaus), D-58453 Witten, Germany.
- Faculty of Biology, Medicine and Health, School of Biological Sciences, University of Manchester, Oxford Rd, Manchester M13 9PL, UK.
| | - Wing-Kee Lee
- Department of Physiology, Pathophysiology & Toxicology and ZBAF (Centre for Biomedical Education and Research), Faculty of Health, School of Medicine, Witten/Herdecke University, Stockumer Str 12 (Thyssenhaus), D-58453 Witten, Germany.
| | - Frank Thévenod
- Department of Physiology, Pathophysiology & Toxicology and ZBAF (Centre for Biomedical Education and Research), Faculty of Health, School of Medicine, Witten/Herdecke University, Stockumer Str 12 (Thyssenhaus), D-58453 Witten, Germany.
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14
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Törnroth-Horsefield S. Phosphorylation of human AQP2 and its role in trafficking. VITAMINS AND HORMONES 2019; 112:95-117. [PMID: 32061351 DOI: 10.1016/bs.vh.2019.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Human Aquaporin 2 (AQP2) is a membrane-bound water channel found in the kidney collecting duct whose regulation by trafficking plays a key role in regulating urine volume. AQP2 trafficking is tightly controlled by the pituitary hormone arginine vasopressin (AVP), which stimulates translocation of AQP2 residing in storage vesicles to the apical membrane. The AVP-dependent translocation of AQP2 to and from the apical membrane is controlled by multiple phosphorylation sites in the AQP2 C-terminus, the phosphorylation of which alters its affinity to proteins within the cellular membrane protein trafficking machinery. The aim of this chapter is to provide a summary of what is currently known about AVP-mediated AQP2 trafficking, dissecting the roles of individual phosphorylation sites, kinases and phosphatases and interacting proteins. From this, the picture of an immensely complex process emerges, of which many structural and molecular details remains to be elucidated.
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15
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Kreida S, Roche JV, Olsson C, Linse S, Törnroth-Horsefield S. Protein-protein interactions in AQP regulation - biophysical characterization of AQP0-CaM and AQP2-LIP5 complex formation. Faraday Discuss 2019; 209:35-54. [PMID: 29972182 DOI: 10.1039/c8fd00065d] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein-protein interactions play important roles in regulating human aquaporins (AQP) by gating as well as trafficking. While structural and functional studies have provided detailed knowledge of AQP transport mechanisms, selectivity as well as gating by conformational changes of loops or termini, the mechanism behind how protein-protein interactions control AQP-mediated water transport through cellular membranes remains poorly characterized. Here we explore the interaction between two human AQPs and regulatory proteins: the interaction between AQP0 and calmodulin, which mediates AQP0 gating, as well as the interaction between AQP2 and LIP5, which is involved in trafficking. Using microscale thermophoresis (MST) and fluorescence anisotropy, two methods that have the advantage of low sample consumption and detergent compatibility, we show that the interactions can be studied using both full-length AQPs and AQP peptides corresponding to the regulatory protein binding sites. However, full-length AQPs gave better reproducibility between methods and for the first time revealed that AQP0 binds CaM in a cooperative manner, which was not seen in experiments using peptides. Our study highlights that, while peptides are great tools for locating binding sites and pinpointing interacting residues, full-length proteins may give additional insights, such as binding mechanism, allostery and cooperativity, important parameters for understanding protein-protein mediated regulation in the cellular context. Our work provides a platform for further studies of AQP regulation that may be of interest for designing drugs that target AQP complexes as well as the development of artificial bio-mimetic water channels for water-purification purposes.
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Affiliation(s)
- Stefan Kreida
- Department of Biochemistry and Structural Biology, Lund University, P.O. Box 124, 221 00 Lund, Sweden.
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16
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The Deubiquitylase USP4 Interacts with the Water Channel AQP2 to Modulate Its Apical Membrane Accumulation and Cellular Abundance. Cells 2019; 8:cells8030265. [PMID: 30901874 PMCID: PMC6468601 DOI: 10.3390/cells8030265] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/18/2019] [Accepted: 03/19/2019] [Indexed: 01/26/2023] Open
Abstract
Aquaporin 2 (AQP2) mediates the osmotic water permeability of the kidney collecting duct in response to arginine vasopressin (VP) and is essential for body water homeostasis. VP effects on AQP2 occur via long-term alterations in AQP2 abundance and short-term changes in AQP2 localization. Several of the effects of VP on AQP2 are dependent on AQP2 phosphorylation and ubiquitylation; post-translational modifications (PTM) that modulate AQP2 subcellular distribution and function. Although several protein kinases, phosphatases, and ubiquitin E3 ligases have been implicated in AQP2 PTM, how AQP2 is deubiquitylated or the role of deubiquitylases (DUBS) in AQP2 function is unknown. Here, we report a novel role of the ubiquitin-specific protease USP4 in modulating AQP2 function. USP4 co-localized with AQP2 in the mouse kidney, and in mpkCCD14 cells USP4 and AQP2 abundance are increased by VP. AQP2 and USP4 co-immunoprecipitated from mpkCCD14 cells and mouse kidney, and in vitro, USP4 can deubiquitylate AQP2. In mpkCCD14 cells, shRNA mediated knockdown of USP4 decreased AQP2 protein abundance, whereas no changes in AQP2 mRNA levels or VP-induced cAMP production were detected. VP-induced AQP2 membrane accumulation in knockdown cells was significantly reduced, which was associated with higher levels of ubiquitylated AQP2. AQP2 protein half-life was also significantly reduced in USP4 knockdown cells. Taken together, the data suggest that USP4 is a key regulator of AQP2 deubiquitylation and that loss of USP4 leads to increased AQP2 ubiquitylation, decreased AQP2 levels, and decreased cell surface AQP2 accumulation upon VP treatment. These studies have implications for understanding body water homeostasis.
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17
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Prado K, Cotelle V, Li G, Bellati J, Tang N, Tournaire-Roux C, Martinière A, Santoni V, Maurel C. Oscillating Aquaporin Phosphorylation and 14-3-3 Proteins Mediate the Circadian Regulation of Leaf Hydraulics. THE PLANT CELL 2019; 31:417-429. [PMID: 30674691 PMCID: PMC6447024 DOI: 10.1105/tpc.18.00804] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/20/2018] [Accepted: 01/16/2019] [Indexed: 05/20/2023]
Abstract
The circadian clock regulates plant tissue hydraulics to synchronize water supply with environmental cycles and thereby optimize growth. The circadian fluctuations in aquaporin transcript abundance suggest that aquaporin water channels play a role in these processes. Here, we show that hydraulic conductivity (K ros) of Arabidopsis (Arabidopsis thaliana) rosettes displays a genuine circadian rhythmicity with a peak around midday. Combined immunological and proteomic approaches revealed that phosphorylation at two C-terminal sites (Ser280, Ser283) of PLASMA MEMBRANE INTRINSIC PROTEIN 2;1 (AtPIP2;1), a major plasma membrane aquaporin in rosettes, shows circadian oscillations and is correlated with K ros Transgenic expression of phosphodeficient and phosphomimetic forms of this aquaporin indicated that AtPIP2;1 phosphorylation is necessary but not sufficient for K ros regulation. We investigated the supporting role of 14-3-3 proteins, which are known to interact with and regulate phosphorylated proteins. Individual knockout plants for five 14-3-3 protein isoforms expressed in rosettes lacked circadian activation of K ros Two of these [GRF4 (14-3-3Phi); GRF10 (14-3-3Epsilon)] showed direct interactions with AtPIP2;1 in the plant and upon coexpression in Xenopus laevis oocytes and activated AtPIP2;1, preferentially when the latter was phosphorylated at its two C-terminal sites. We propose that this regulatory mechanism assists in the activation of phosphorylated AtPIP2;1 during circadian regulation of K ros.
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Affiliation(s)
- Karine Prado
- Biochimie et Physiologie Moléculaire des Plantes, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, 34090 Montpellier, France
| | - Valérie Cotelle
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS, 24 chemin de Borde Rouge, Auzeville, BP 42617, F-31326, Castanet-Tolosan, France
| | - Guowei Li
- Biochimie et Physiologie Moléculaire des Plantes, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, 34090 Montpellier, France
| | - Jorge Bellati
- Biochimie et Physiologie Moléculaire des Plantes, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, 34090 Montpellier, France
| | - Ning Tang
- Biochimie et Physiologie Moléculaire des Plantes, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, 34090 Montpellier, France
| | - Colette Tournaire-Roux
- Biochimie et Physiologie Moléculaire des Plantes, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, 34090 Montpellier, France
| | - Alexandre Martinière
- Biochimie et Physiologie Moléculaire des Plantes, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, 34090 Montpellier, France
| | - Véronique Santoni
- Biochimie et Physiologie Moléculaire des Plantes, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, 34090 Montpellier, France
| | - Christophe Maurel
- Biochimie et Physiologie Moléculaire des Plantes, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, 34090 Montpellier, France
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18
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Cai N, Lou L, Al-Saadi N, Tetteh S, Runnels LW. The kinase activity of the channel-kinase protein TRPM7 regulates stability and localization of the TRPM7 channel in polarized epithelial cells. J Biol Chem 2018; 293:11491-11504. [PMID: 29866880 DOI: 10.1074/jbc.ra118.001925] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/25/2018] [Indexed: 12/13/2022] Open
Abstract
The channel-kinase transient receptor potential melastatin 7 (TRPM7) is a bifunctional protein with ion channel and kinase domains. The kinase activity of TRPM7 has been linked to the regulation of a broad range of cellular activities, but little is understood as to how the channel itself is regulated by its own kinase activity. Here, using several mammalian cell lines expressing WT TRPM7 or kinase-inactive variants, we discovered that compared with the cells expressing WT TRPM7, cells in which TRPM7's kinase activity was inactivated had faster degradation, elevated ubiquitination, and increased intracellular retention of the channel. Mutational analysis of TRPM7 autophosphorylation sites further revealed a role for Ser-1360 of TRPM7 as a key residue mediating both TRPM7 stability and intracellular trafficking. Additional trafficking roles were uncovered for Ser-1403 and Ser-1567, whose phosphorylation by TRPM7's kinase activity mediated the interaction of the channel with the signaling protein 14-3-3θ. In summary, our results point to a critical role for TRPM7's kinase activity in regulating proteasome-mediated turnover of the TRPM7 channel and controlling its cellular localization in polarized epithelial cells. Overall, these findings improve our understanding of the significance of TRPM7's kinase activity for functional regulation of its channel activity.
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Affiliation(s)
- Na Cai
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Liping Lou
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Namariq Al-Saadi
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854; University of Misan, Amarah 62001, Iraq
| | - Sandra Tetteh
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Loren W Runnels
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854.
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19
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Inamdar SM, Lankford CK, Laird JG, Novbatova G, Tatro N, Whitmore SS, Scheetz TE, Baker SA. Analysis of 14-3-3 isoforms expressed in photoreceptors. Exp Eye Res 2018; 170:108-116. [PMID: 29486162 DOI: 10.1016/j.exer.2018.02.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 02/02/2018] [Accepted: 02/23/2018] [Indexed: 11/18/2022]
Abstract
The 14-3-3 family of proteins has undergone considerable expansion in higher eukaryotes with humans and mice expressing seven isoforms (β, ε, η, γ, θ, ζ, and σ) from seven distinct genes (YWHAB, YWAHE, YWHAH, YWHAG, YWHAQ, YWHAZ, and SFN). Growing evidence indicates that while highly conserved, these isoforms are not entirely functionally redundant as they exhibit unique tissue expression profiles, subcellular localization, and biochemical functions. A key limitation in our understanding of 14-3-3 biology lies in our limited knowledge of cell-type specific 14-3-3 expression. Here we provide a characterization of 14-3-3 expression in whole retina and isolated rod photoreceptors using reverse-transcriptase digital droplet PCR. We find that all 14-3-3 genes with the exception of SFN are expressed in mouse retina with YWHAQ and YWHAE being the most highly expressed. Rod photoreceptors are enriched in YWHAE (14-3-3 ε). Immunohistochemistry revealed that 14-3-3 ε and 14-3-3 ζ exhibit unique distributions in photoreceptors with 14-3-3 ε restricted to the inner segment and 14-3-3 ζ localized to the outer segment. Our data demonstrates that, in the retina, 14-3-3 isoforms likely serve specific functions as they exhibit unique expression levels and cell-type specificity. As such, future investigations into 14-3-3 function in rod photoreceptors should be centered on 14-3-3 ε and 14-3-3 ζ, depending on the subcellular region of question.
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Affiliation(s)
- Shivangi M Inamdar
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Colten K Lankford
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Joseph G Laird
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Gulnara Novbatova
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Nicole Tatro
- Department of Ophthalmology & Visual Sciences and Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - S Scott Whitmore
- Department of Ophthalmology & Visual Sciences and Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Todd E Scheetz
- Department of Ophthalmology & Visual Sciences and Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Sheila A Baker
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA; Department of Ophthalmology & Visual Sciences and Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.
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20
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Chou CL, Hwang G, Hageman DJ, Han L, Agrawal P, Pisitkun T, Knepper MA. Identification of UT-A1- and AQP2-interacting proteins in rat inner medullary collecting duct. Am J Physiol Cell Physiol 2018; 314:C99-C117. [PMID: 29046292 PMCID: PMC5866378 DOI: 10.1152/ajpcell.00082.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 10/13/2017] [Accepted: 10/13/2017] [Indexed: 11/22/2022]
Abstract
The urea channel UT-A1 and the water channel aquaporin-2 (AQP2) mediate vasopressin-regulated transport in the renal inner medullary collecting duct (IMCD). To identify the proteins that interact with UT-A1 and AQP2 in native rat IMCD cells, we carried out chemical cross-linking followed by detergent solubilization, immunoprecipitation, and LC-MS/MS analysis of the immunoprecipitated material. The analyses revealed 133 UT-A1-interacting proteins and 139 AQP2-interacting proteins, each identified in multiple replicates. Fifty-three proteins that were present in both the UT-A1 and the AQP2 interactomes can be considered as mediators of housekeeping interactions, likely common to all plasma membrane proteins. Among proteins unique to the UT-A1 list were those involved in posttranslational modifications: phosphorylation (protein kinases Cdc42bpb, Phkb, Camk2d, and Mtor), ubiquitylation/deubiquitylation (Uba1, Usp9x), and neddylation (Nae1 and Uba3). Among the proteins unique to the AQP2 list were several Rab proteins (Rab1a, Rab2a, Rab5b, Rab5c, Rab7a, Rab11a, Rab11b, Rab14, Rab17) involved in membrane trafficking. UT-A1 was found to interact with UT-A3, although quantitative proteomics revealed that most UT-A1 molecules in the cell are not bound to UT-A3. In vitro incubation of UT-A1 peptides with the protein kinases identified in the UT-A1 interactome revealed that all except Mtor were capable of phosphorylating known sites in UT-A1. Overall, the UT-A1 and AQP2 interactomes provide a snapshot of a dynamic process in which UT-A1 and AQP2 are produced in the rough endoplasmic reticulum, processed through the Golgi apparatus, delivered to endosomes that move into and out of the plasma membrane, and are regulated in the plasma membrane.
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Affiliation(s)
- Chung-Lin Chou
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Gloria Hwang
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Daniel J Hageman
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Lichy Han
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Prashasti Agrawal
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Trairak Pisitkun
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
- Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand
| | - Mark A Knepper
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
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21
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Basolateral cholesterol depletion alters Aquaporin-2 post-translational modifications and disrupts apical plasma membrane targeting. Biochem Biophys Res Commun 2018; 495:157-162. [DOI: 10.1016/j.bbrc.2017.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 11/01/2017] [Indexed: 11/22/2022]
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22
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Wu Q, Moeller HB, Stevens DA, Sanchez-Hodge R, Childers G, Kortenoeven MLA, Cheng L, Rosenbaek LL, Rubel C, Patterson C, Pisitkun T, Schisler JC, Fenton RA. CHIP Regulates Aquaporin-2 Quality Control and Body Water Homeostasis. J Am Soc Nephrol 2017; 29:936-948. [PMID: 29242247 DOI: 10.1681/asn.2017050526] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 11/14/2017] [Indexed: 02/03/2023] Open
Abstract
The importance of the kidney distal convoluted tubule (DCT) and cortical collecting duct (CCD) is highlighted by various water and electrolyte disorders that arise when the unique transport properties of these segments are disturbed. Despite this critical role, little is known about which proteins have a regulatory role in these cells and how these cells can be regulated by individual physiologic stimuli. By combining proteomics, bioinformatics, and cell biology approaches, we found that the E3 ubiquitin ligase CHIP is highly expressed throughout the collecting duct; is modulated in abundance by vasopressin; interacts with aquaporin-2 (AQP2), Hsp70, and Hsc70; and can directly ubiquitylate the water channel AQP2 in vitro shRNA knockdown of CHIP in CCD cells increased AQP2 protein t1/2 and reduced AQP2 ubiquitylation, resulting in greater levels of AQP2 and phosphorylated AQP2. CHIP knockdown increased the plasma membrane abundance of AQP2 in these cells. Compared with wild-type controls, CHIP knockout mice or novel CRISPR/Cas9 mice without CHIP E3 ligase activity had greater AQP2 abundance and altered renal water handling, with decreased water intake and urine volume, alongside higher urine osmolality. We did not observe significant changes in other water- or sodium-transporting proteins in the gene-modified mice. In summary, these results suggest that CHIP regulates AQP2 and subsequently, renal water handling.
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Affiliation(s)
- Qi Wu
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Hanne B Moeller
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Rebekah Sanchez-Hodge
- McAllister Heart Institute and.,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Gabrielle Childers
- McAllister Heart Institute and.,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | | | - Lei Cheng
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Lena L Rosenbaek
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | | | - Cam Patterson
- Presbyterian Hospital/Weill-Cornell Medical Center, New York, New York; and
| | - Trairak Pisitkun
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Jonathan C Schisler
- McAllister Heart Institute and.,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Robert A Fenton
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark;
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23
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Okamoto CT. Regulation of Transporters and Channels by Membrane-Trafficking Complexes in Epithelial Cells. Cold Spring Harb Perspect Biol 2017; 9:a027839. [PMID: 28246186 PMCID: PMC5666629 DOI: 10.1101/cshperspect.a027839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The vectorial secretion and absorption of fluid and solutes by epithelial cells is dependent on the polarized expression of membrane solute transporters and channels at the apical and basolateral membranes. The establishment and maintenance of this polarized expression of transporters and channels are affected by divers protein-trafficking complexes. Moreover, regulation of the magnitude of transport is often under control of physiological stimuli, again through the interaction of transporters and channels with protein-trafficking complexes. This review highlights the value in utilizing transporters and channels as cargo to characterize core trafficking machinery by which epithelial cells establish and maintain their polarized expression, and how this machinery regulates fluid and solute transport in response to physiological stimuli.
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Affiliation(s)
- Curtis T Okamoto
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089-9121
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24
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Roche JV, Survery S, Kreida S, Nesverova V, Ampah-Korsah H, Gourdon M, Deen PMT, Törnroth-Horsefield S. Phosphorylation of human aquaporin 2 (AQP2) allosterically controls its interaction with the lysosomal trafficking protein LIP5. J Biol Chem 2017; 292:14636-14648. [PMID: 28710278 DOI: 10.1074/jbc.m117.788364] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 07/07/2017] [Indexed: 12/21/2022] Open
Abstract
The interaction between the renal water channel aquaporin-2 (AQP2) and the lysosomal trafficking regulator-interacting protein LIP5 targets AQP2 to multivesicular bodies and facilitates lysosomal degradation. This interaction is part of a process that controls AQP2 apical membrane abundance in a vasopressin-dependent manner, allowing for urine volume adjustment. Vasopressin regulates phosphorylation at four sites within the AQP2 C terminus (Ser256, Ser261, Ser264, and Thr269), of which Ser256 is crucial and sufficient for AQP2 translocation from storage vesicles to the apical membrane. However, whether AQP2 phosphorylation modulates AQP2-LIP5 complex affinity is unknown. Here we used far-Western blot analysis and microscale thermophoresis to show that the AQP2 binds LIP5 in a phosphorylation-dependent manner. We constructed five phospho-mimicking mutants (S256E, S261E, S264E, T269E, and S256E/T269E) and a C-terminal truncation mutant (ΔP242) that lacked all phosphorylation sites but retained a previously suggested LIP5-binding site. CD spectroscopy indicated that wild-type AQP2 and the phospho-mimicking mutants had similar overall structure but displayed differences in melting temperatures possibly arising from C-terminal conformational changes. Non-phosphorylated AQP2 bound LIP5 with the highest affinity, whereas AQP2-ΔP242 had 20-fold lower affinity as determined by microscale thermophoresis. AQP2-S256E, S261E, T269E, and S256E/T269E all had reduced affinity. This effect was most prominent for AQP2-S256E, which fits well with its role in apical membrane targeting. AQP2-S264E had affinity similar to non-phosphorylated AQP2, possibly indicating a role in exosome excretion. Our data suggest that AQP2 phosphorylation allosterically controls its interaction with LIP5, illustrating how altered affinities to interacting proteins form the basis for regulation of AQP2 trafficking by post-translational modifications.
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Affiliation(s)
- Jennifer Virginia Roche
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Sabeen Survery
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Stefan Kreida
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Veronika Nesverova
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Henry Ampah-Korsah
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Maria Gourdon
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Peter M T Deen
- the Department of Physiology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
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25
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Jung HJ, Kwon TH. Molecular mechanisms regulating aquaporin-2 in kidney collecting duct. Am J Physiol Renal Physiol 2016; 311:F1318-F1328. [PMID: 27760771 DOI: 10.1152/ajprenal.00485.2016] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 10/11/2016] [Accepted: 10/11/2016] [Indexed: 01/04/2023] Open
Abstract
The kidney collecting duct is an important renal tubular segment for regulation of body water homeostasis and urine concentration. Water reabsorption in the collecting duct principal cells is controlled by vasopressin, a peptide hormone that induces the osmotic water transport across the collecting duct epithelia through regulation of water channel proteins aquaporin-2 (AQP2) and aquaporin-3 (AQP3). In particular, vasopressin induces both intracellular translocation of AQP2-bearing vesicles to the apical plasma membrane and transcription of the Aqp2 gene to increase AQP2 protein abundance. The signaling pathways, including AQP2 phosphorylation, RhoA phosphorylation, intracellular calcium mobilization, and actin depolymerization, play a key role in the translocation of AQP2. This review summarizes recent data demonstrating the regulation of AQP2 as the underlying molecular mechanism for the homeostasis of water balance in the body.
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Affiliation(s)
- Hyun Jun Jung
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and
| | - Tae-Hwan Kwon
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea
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26
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Yde J, Keely S, Wu Q, Borg JF, Lajczak N, O'Dwyer A, Dalsgaard P, Fenton RA, Moeller HB. Characterization of AQPs in Mouse, Rat, and Human Colon and Their Selective Regulation by Bile Acids. Front Nutr 2016; 3:46. [PMID: 27777930 PMCID: PMC5056181 DOI: 10.3389/fnut.2016.00046] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 09/26/2016] [Indexed: 12/12/2022] Open
Abstract
In normal individuals, the epithelium of the colon absorbs 1.5–2 l of water a day to generate dehydrated feces. However, in the condition of bile acid malabsorption (BAM), an excess of bile acids in the colon results in diarrhea. Several studies have attempted to address the mechanisms contributing to BAM induced by various bile acids. However, none have addressed a potential dysregulation of aquaporin (AQP) water channels, which are responsible for the majority of transcellular water transport in epithelial cells, as a contributing factor to the onset of diarrhea and the pathogenesis of BAM. In this study, we aimed to systematically analyze the expression of AQPs in colonic epithelia from rat, mouse, and human and determine whether their expression is altered in a rat model of BAM. Mass spectrometry-based proteomics, RT-PCR, and western blotting identified various AQPs in isolated colonic epithelial cells from rats (AQP1, 3, 4, 7, 8) and mice (AQP1, 4, 8). Several AQPs were also detected in human colon (AQP1, 3, 4, 7–9). Immunohistochemistry localized AQP1 to the apical plasma membrane of epithelial cells in the bottom of the crypts, whereas AQP3 (rat, human) and AQP4 (mice, human) were localized predominantly in the basolateral plasma membrane. AQP8 was localized intracellularly and at the apical plasma membrane of epithelial cells. Rats fed sodium cholate for 72 h had significantly increased fecal water content, suggesting development of BAM-associated diarrhea. Colonic epithelial cells isolated from this model had significantly altered levels of AQP3, 7, and 8, suggesting that these AQPs may be involved in the pathogenesis of bile acid-induced diarrhea.
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Affiliation(s)
- Jonathan Yde
- Department of Biomedicine, InterPrET Center, Aarhus University , Aarhus , Denmark
| | - Stephen Keely
- RCSI Education and Research Centre, Royal College of Surgeons in Ireland, Beaumont Hospital , Dublin , Ireland
| | - Qi Wu
- Department of Biomedicine, InterPrET Center, Aarhus University , Aarhus , Denmark
| | - Johan F Borg
- Department of Biomedicine, InterPrET Center, Aarhus University , Aarhus , Denmark
| | - Natalia Lajczak
- RCSI Education and Research Centre, Royal College of Surgeons in Ireland, Beaumont Hospital , Dublin , Ireland
| | - Aoife O'Dwyer
- RCSI Education and Research Centre, Royal College of Surgeons in Ireland, Beaumont Hospital , Dublin , Ireland
| | | | - Robert A Fenton
- Department of Biomedicine, InterPrET Center, Aarhus University , Aarhus , Denmark
| | - Hanne B Moeller
- Department of Biomedicine, InterPrET Center, Aarhus University , Aarhus , Denmark
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27
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Al-Bataineh MM, Li H, Ohmi K, Gong F, Marciszyn AL, Naveed S, Zhu X, Neumann D, Wu Q, Cheng L, Fenton RA, Pastor-Soler NM, Hallows KR. Activation of the metabolic sensor AMP-activated protein kinase inhibits aquaporin-2 function in kidney principal cells. Am J Physiol Renal Physiol 2016; 311:F890-F900. [PMID: 27534994 PMCID: PMC5130465 DOI: 10.1152/ajprenal.00308.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/15/2016] [Indexed: 11/22/2022] Open
Abstract
Aquaporin-2 (AQP2) is essential to maintain body water homeostasis. AQP2 traffics from intracellular vesicles to the apical membrane of kidney collecting duct principal cells in response to vasopressin [arginine vasopressin (AVP)], a hormone released with low intravascular volume, which causes decreased kidney perfusion. Decreased kidney perfusion activates AMP-activated kinase (AMPK), a metabolic sensor that inhibits the activity of several transport proteins. We hypothesized that AMPK activation also inhibits AQP2 function. These putative AMPK effects could protect interstitial ionic gradients required for urinary concentration during metabolic stress when low intravascular volume induces AVP release. Here we found that short-term AMPK activation by treatment with 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR; 75 min) in kidney tissue prevented baseline AQP2 apical accumulation in principal cells, but did not prevent AQP2 apical accumulation in response to the AVP analog desmopressin (dDAVP). Prolonged AMPK activation prevented AQP2 cell membrane accumulation in response to forskolin in mouse collecting duct mpkCCDc14 cells. Moreover, AMPK inhibition accelerated hypotonic lysis of Xenopus oocytes expressing AQP2. We performed phosphorylation assays to elucidate the mechanism by which AMPK regulates AQP2. Although AMPK weakly phosphorylated immunoprecipitated AQP2 in vitro, no direct AMPK phosphorylation of the AQP2 COOH-terminus was detected by mass spectrometry. AMPK promoted Ser-261 phosphorylation and antagonized dDAVP-dependent phosphorylation of other AQP2 COOH-terminal sites in cells. Our findings suggest an increasing, time-dependent antagonism of AMPK on AQP2 regulation with AICAR-dependent inhibition of cAMP-dependent apical accumulation and AVP-dependent phosphorylation of AQP2. This inhibition likely occurs via a mechanism that does not involve direct AQP2 phosphorylation by AMPK.
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Affiliation(s)
- Mohammad M Al-Bataineh
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Hui Li
- Department of Medicine, University of Southern California/University Kidney Research Organization, Kidney Research Center, Division of Nephrology and Hypertension, Keck School of Medicine of University of Southern California, Los Angeles, California
| | - Kazuhiro Ohmi
- Department of Medicine, University of Southern California/University Kidney Research Organization, Kidney Research Center, Division of Nephrology and Hypertension, Keck School of Medicine of University of Southern California, Los Angeles, California
| | - Fan Gong
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Allison L Marciszyn
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Sajid Naveed
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Xiaoqing Zhu
- Department of Molecular Genetics, School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; and
| | - Dietbert Neumann
- Department of Molecular Genetics, School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; and
| | - Qi Wu
- Department of Biomedicine, InterPrET Center, Aarhus University, Aarhus, Denmark
| | - Lei Cheng
- Department of Biomedicine, InterPrET Center, Aarhus University, Aarhus, Denmark
| | - Robert A Fenton
- Department of Biomedicine, InterPrET Center, Aarhus University, Aarhus, Denmark
| | - Núria M Pastor-Soler
- Department of Medicine, University of Southern California/University Kidney Research Organization, Kidney Research Center, Division of Nephrology and Hypertension, Keck School of Medicine of University of Southern California, Los Angeles, California;
| | - Kenneth R Hallows
- Department of Medicine, University of Southern California/University Kidney Research Organization, Kidney Research Center, Division of Nephrology and Hypertension, Keck School of Medicine of University of Southern California, Los Angeles, California
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