1
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Sneddon WB, Ramineni S, Van Doorn GE, Hepler JR, Friedman PA. Distinct and overlapping RGS14 and RGS12 actions regulate NPT2A-mediated phosphate transport. Biochem Biophys Res Commun 2024; 733:150700. [PMID: 39293332 DOI: 10.1016/j.bbrc.2024.150700] [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: 09/06/2024] [Revised: 09/09/2024] [Accepted: 09/13/2024] [Indexed: 09/20/2024]
Abstract
Parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23) control serum phosphate levels by downregulating the renal Na-phosphate transporter NPT2A, thereby decreasing phosphate absorption and augmenting urinary excretion. This mechanism requires NHERF1, a PDZ scaffold protein, and is governed by the regulator of G protein signaling-14 (RGS14), which harbors a carboxy-terminal PDZ ligand that binds NHERF1. RGS14 is part of a triad of structurally related RGS proteins that includes RGS12 and RGS10. Like RGS14, RGS12 contains a class 1 PDZ ligand. However, unlike RGS14, the larger RGS12 contains an upstream PDZ-binding domain. The studies outlined here examined and characterized the binding of RGS12 with NHERF1 and NPT2A and its function on hormone-regulated phosphate transport. Immunoblotting experiments revealed RGS12 C-terminal PDZ ligand binding to NHERF1. Further structural analysis disclosed that NPT2A engaged full-length RGS12 and the upstream fragment containing the PDZ domain. Neither the downstream RGS12 portion nor RGS14 interacted with NPT2A. PTH and FGF23 profoundly inhibited phosphate uptake in opossum kidney proximal tubule cells. Transfection with human RGS14, or human RGS12, abolished hormone-sensitive phosphate transport as reported for human proximal tubule cells. RGS12 inhibitory activity resides in the downstream region and is comparable to RGS14. The carboxy-terminal RGS12(667-1447) splice variant is prominently expressed in the kidney and may contribute to regulating hormone-sensitive phosphate transport.
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Affiliation(s)
- W Bruce Sneddon
- Laboratory for GPCR Biology, Departments of Pharmacology and Chemical Biology, USA
| | - Suneela Ramineni
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, USA
| | - G Emme Van Doorn
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, USA
| | - John R Hepler
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, USA
| | - Peter A Friedman
- Laboratory for GPCR Biology, Departments of Pharmacology and Chemical Biology, USA; Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, USA.
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2
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Walker V. The Intricacies of Renal Phosphate Reabsorption-An Overview. Int J Mol Sci 2024; 25:4684. [PMID: 38731904 PMCID: PMC11083860 DOI: 10.3390/ijms25094684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/13/2024] Open
Abstract
To maintain an optimal body content of phosphorus throughout postnatal life, variable phosphate absorption from food must be finely matched with urinary excretion. This amazing feat is accomplished through synchronised phosphate transport by myriads of ciliated cells lining the renal proximal tubules. These respond in real time to changes in phosphate and composition of the renal filtrate and to hormonal instructions. How they do this has stimulated decades of research. New analytical techniques, coupled with incredible advances in computer technology, have opened new avenues for investigation at a sub-cellular level. There has been a surge of research into different aspects of the process. These have verified long-held beliefs and are also dramatically extending our vision of the intense, integrated, intracellular activity which mediates phosphate absorption. Already, some have indicated new approaches for pharmacological intervention to regulate phosphate in common conditions, including chronic renal failure and osteoporosis, as well as rare inherited biochemical disorders. It is a rapidly evolving field. The aim here is to provide an overview of our current knowledge, to show where it is leading, and where there are uncertainties. Hopefully, this will raise questions and stimulate new ideas for further research.
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Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton General Hospital, Southampton S016 6YD, UK
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3
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Friedman P, Mamonova T. The molecular sociology of NHERF1 PDZ proteins controlling renal hormone-regulated phosphate transport. Biosci Rep 2024; 44:BSR20231380. [PMID: 38465463 PMCID: PMC10987488 DOI: 10.1042/bsr20231380] [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: 10/31/2023] [Revised: 03/07/2024] [Accepted: 03/08/2024] [Indexed: 03/12/2024] Open
Abstract
Parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23) control extracellular phosphate levels by regulating renal NPT2A-mediated phosphate transport by a process requiring the PDZ scaffold protein NHERF1. NHERF1 possesses two PDZ domains, PDZ1 and PDZ2, with identical core-binding GYGF motifs explicitly recognizing distinct binding partners that play different and specific roles in hormone-regulated phosphate transport. The interaction of PDZ1 and the carboxy-terminal PDZ-binding motif of NPT2A (C-TRL) is required for basal phosphate transport. PDZ2 is a regulatory domain that scaffolds multiple biological targets, including kinases and phosphatases involved in FGF23 and PTH signaling. FGF23 and PTH trigger disassembly of the NHERF1-NPT2A complex through reversible hormone-stimulated phosphorylation with ensuing NPT2A sequestration, down-regulation, and cessation of phosphate absorption. In the absence of NHERF1-NPT2A interaction, inhibition of FGF23 or PTH signaling results in disordered phosphate homeostasis and phosphate wasting. Additional studies are crucial to elucidate how NHERF1 spatiotemporally coordinates cellular partners to regulate extracellular phosphate levels.
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Affiliation(s)
- Peter A. Friedman
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, U.S.A
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, U.S.A
| | - Tatyana Mamonova
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, U.S.A
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4
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Stewart BZ, Mamonova T, Sneddon WB, Javorsky A, Yang Y, Wang B, Nolin TD, Humbert PO, Friedman PA, Kvansakul M. Scribble scrambles parathyroid hormone receptor interactions to regulate phosphate and vitamin D homeostasis. Proc Natl Acad Sci U S A 2023; 120:e2220851120. [PMID: 37252981 PMCID: PMC10266016 DOI: 10.1073/pnas.2220851120] [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: 12/07/2022] [Accepted: 03/30/2023] [Indexed: 06/01/2023] Open
Abstract
G protein-coupled receptors, including PTHR, are pivotal for controlling metabolic processes ranging from serum phosphate and vitamin D levels to glucose uptake, and cytoplasmic interactors may modulate their signaling, trafficking, and function. We now show that direct interaction with Scribble, a cell polarity-regulating adaptor protein, modulates PTHR activity. Scribble is a crucial regulator for establishing and developing tissue architecture, and its dysregulation is involved in various disease conditions, including tumor expansion and viral infections. Scribble co-localizes with PTHR at basal and lateral surfaces in polarized cells. Using X-ray crystallography, we show that colocalization is mediated by engaging a short sequence motif at the PTHR C-terminus using Scribble PDZ1 and PDZ3 domain, with binding affinities of 31.7 and 13.4 μM, respectively. Since PTHR controls metabolic functions by actions on renal proximal tubules, we engineered mice to selectively knockout Scribble in proximal tubules. The loss of Scribble impacted serum phosphate and vitamin D levels and caused significant plasma phosphate elevation and increased aggregate vitamin D3 levels, whereas blood glucose levels remained unchanged. Collectively these results identify Scribble as a vital regulator of PTHR-mediated signaling and function. Our findings reveal an unexpected link between renal metabolism and cell polarity signaling.
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Affiliation(s)
- Bryce Z. Stewart
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC3086, Australia
| | - Tatyana Mamonova
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA15261
| | - W. Bruce Sneddon
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA15261
| | - Airah Javorsky
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC3086, Australia
| | - Yanmei Yang
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA15261
| | - Bin Wang
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA15261
| | - Thomas D. Nolin
- Department of Pharmacy and Therapeutics, Center for Clinical Pharmaceutical Sciences, University of Pittsburgh Schools of Pharmacy and Medicine, Pittsburgh, PA15216
- Department of Medicine Schools of Pharmacy and Medicine Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, PA15216
| | - Patrick O. Humbert
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC3086, Australia
- Department of Biochemistry & Pharmacology, University of Melbourne, Melbourne, VIC3010, Australia
- Department of Clinical Pathology, University of Melbourne, Melbourne, VIC3010, Australia
| | - Peter A. Friedman
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA15261
| | - Marc Kvansakul
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC3086, Australia
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5
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Sneddon WB, Friedman PA, Mamonova T. Mutations in an unrecognized internal NPT2A PDZ motif disrupt phosphate transport and cause congenital hypophosphatemia. Biochem J 2023; 480:685-699. [PMID: 37132631 PMCID: PMC10442799 DOI: 10.1042/bcj20230020] [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: 01/20/2023] [Revised: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/04/2023]
Abstract
The Na+-dependent phosphate cotransporter-2A (NPT2A, SLC34A1) is a primary regulator of extracellular phosphate homeostasis. Its most prominent structural element is a carboxy-terminal PDZ ligand that binds Na+/H+ Exchanger Regulatory Factor-1 (NHERF1, SLC9A3R1). NHERF1, a multidomain PDZ protein, establishes NPT2A membrane localization and is required for hormone-inhibitable phosphate transport. NPT2A also possesses an uncharacterized internal PDZ ligand. Two recent clinical reports describe congenital hypophosphatemia in children harboring Arg495His or Arg495Cys variants within the internal PDZ motif. The wild-type internal 494TRL496 PDZ ligand binds NHERF1 PDZ2, which we consider a regulatory domain. Ablating the internal PDZ ligand with a 494AAA496 substitution blocked hormone-inhibitable phosphate transport. Complementary approaches, including CRISPR/Cas9 technology, site-directed mutagenesis, confocal microscopy, and modeling, showed that NPT2A Arg495His or Arg495Cys variants do not support PTH or FGF23 action on phosphate transport. Coimmunoprecipitation experiments indicate that both variants bind NHERF1 similarly to WT NPT2A. However, in contrast with WT NPT2A, NPT2A Arg495His, or Arg495Cys variants remain at the apical membrane and are not internalized in response to PTH. We predict that Cys or His substitution of the charged Arg495 changes the electrostatics, preventing phosphorylation of the upstream Thr494, interfering with phosphate uptake in response to hormone action, and inhibiting NPT2A trafficking. We advance a model wherein the carboxy-terminal PDZ ligand defines apical localization NPT2A, while the internal PDZ ligand is essential for hormone-triggered phosphate transport.
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Affiliation(s)
- W. Bruce Sneddon
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Peter A. Friedman
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Tatyana Mamonova
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
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6
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Sneddon WB, Friedman PA, Mamonova T. Mutations in an unrecognized internal NPT2A PDZ motif disrupt phosphate transport causing congenital hypophosphatemia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.06.531332. [PMID: 36945373 PMCID: PMC10028803 DOI: 10.1101/2023.03.06.531332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
The Na + -dependent phosphate cotransporter-2A (NPT2A, SLC34A1) is a primary regulator of extracellular phosphate homeostasis. Its most prominent structural element is a carboxy-terminal PDZ ligand that binds Na + /H + Exchanger Regulatory Factor-1 (NHERF1, SLC9A3R1). NHERF1, a multidomain PDZ protein,establishes NPT2A membrane localization and is required for hormone-sensitive phosphate transport. NPT2A also possesses an uncharacterized internal PDZ ligand. Two recent clinical reports describe congenital hypophosphatemia in children harboring Arg 495 His or Arg 495 Cys variants within the internal PDZ motif. The wild-type internal 494 TRL 496 PDZ ligand binds NHERF1 PDZ2, which we consider a regulatory domain. Ablating the internal PDZ ligand with a 494 AAA 496 substitution blocked hormone-sensitive phosphate transport. Complementary approaches, including CRISPR/Cas9 technology, site-directed mutagenesis, confocal microscopy, and modeling, showed that NPT2A Arg 495 His or Arg 495 Cys variants do not support PTH or FGF23 action on phosphate transport. Coimmunoprecipitation experiments indicate that both variants bind NHERF1 similarly to WT NPT2A. However, in contrast to WT NPT2A, NPT2A Arg 495 His or Arg 495 Cys variants remain at the apical membrane and are not internalized in response to PTH. We predict that Cys or His substitution of the charged Arg 495 changes the electrostatics, preventing phosphorylation of the upstream Thr 494 , interfering with phosphate uptake in response to hormone action, and inhibiting NPT2A trafficking. We advance a model wherein the carboxyterminal PDZ ligand defines apical localization NPT2A, while the internal PDZ ligand is essential for hormone-triggered phosphate transport.
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7
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Friedman PA, Sneddon WB, Mamonova T, Montanez-Miranda C, Ramineni S, Harbin NH, Squires KE, Gefter JV, Magyar CE, Emlet DR, Hepler JR. RGS14 regulates PTH- and FGF23-sensitive NPT2A-mediated renal phosphate uptake via binding to the NHERF1 scaffolding protein. J Biol Chem 2022; 298:101836. [PMID: 35307350 PMCID: PMC9035407 DOI: 10.1016/j.jbc.2022.101836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 03/04/2022] [Accepted: 03/06/2022] [Indexed: 02/06/2023] Open
Abstract
Phosphate homeostasis, mediated by dietary intake, renal absorption, and bone deposition, is incompletely understood because of the uncharacterized roles of numerous implicated protein factors. Here, we identified a novel role for one such element, regulator of G protein signaling 14 (RGS14), suggested by genome-wide association studies to associate with dysregulated Pi levels. We show that human RGS14 possesses a carboxy-terminal PDZ ligand required for sodium phosphate cotransporter 2a (NPT2A) and sodium hydrogen exchanger regulatory factor-1 (NHERF1)-mediated renal Pi transport. In addition, we found using isotope uptake measurements combined with bioluminescence resonance energy transfer assays, siRNA knockdown, pull-down and overlay assays, and molecular modeling that secreted proteins parathyroid hormone (PTH) and fibroblast growth factor 23 inhibited Pi uptake by inducing dissociation of the NPT2A-NHERF1 complex. PTH failed to affect Pi transport in cells expressing RGS14, suggesting that it suppresses hormone-sensitive but not basal Pi uptake. Interestingly, RGS14 did not affect PTH-directed G protein activation or cAMP formation, implying a postreceptor site of action. Further pull-down experiments and direct binding assays indicated that NPT2A and RGS14 bind distinct PDZ domains on NHERF1. We showed that RGS14 expression in human renal proximal tubule epithelial cells blocked the effects of PTH and fibroblast growth factor 23 and stabilized the NPT2A-NHERF1 complex. In contrast, RGS14 genetic variants bearing mutations in the PDZ ligand disrupted RGS14 binding to NHERF1 and subsequent PTH-sensitive Pi transport. In conclusion, these findings identify RGS14 as a novel regulator of hormone-sensitive Pi transport. The results suggest that changes in RGS14 function or abundance may contribute to the hormone resistance and hyperphosphatemia observed in kidney diseases.
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Affiliation(s)
- Peter A Friedman
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
| | - W Bruce Sneddon
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Tatyana Mamonova
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Carolina Montanez-Miranda
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Suneela Ramineni
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Nicholas H Harbin
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Katherine E Squires
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Julia V Gefter
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Clara E Magyar
- Department of Pathology and Laboratory Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - David R Emlet
- Center for Critical Care Nephrology, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - John R Hepler
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA.
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8
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Vistrup-Parry M, Sneddon WB, Bach S, Strømgaard K, Friedman PA, Mamonova T. Multisite NHERF1 phosphorylation controls GRK6A regulation of hormone-sensitive phosphate transport. J Biol Chem 2021; 296:100473. [PMID: 33639163 PMCID: PMC8042174 DOI: 10.1016/j.jbc.2021.100473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 12/13/2022] Open
Abstract
The type II sodium-dependent phosphate cotransporter (NPT2A) mediates renal phosphate uptake. The NPT2A is regulated by parathyroid hormone (PTH) and fibroblast growth factor 23, which requires Na+/H+ exchange regulatory factor-1 (NHERF1), a multidomain PDZ-containing phosphoprotein. Phosphocycling controls the association between NHERF1 and the NPT2A. Here, we characterize the critical involvement of G protein–coupled receptor kinase 6A (GRK6A) in mediating PTH-sensitive phosphate transport by targeted phosphorylation coupled with NHERF1 conformational rearrangement, which in turn allows phosphorylation at a secondary site. GRK6A, through its carboxy-terminal PDZ recognition motif, binds NHERF1 PDZ1 with greater affinity than PDZ2. However, the association between NHERF1 PDZ2 and GRK6A is necessary for PTH action. Ser162, a PKCα phosphorylation site in PDZ2, regulates the binding affinity between PDZ2 and GRK6A. Substitution of Ser162 with alanine (S162A) blocks the PTH action but does not disrupt the interaction between NHERF1 and the NPT2A. Replacement of Ser162 with aspartic acid (S162D) abrogates the interaction between NHERF1 and the NPT2A and concurrently PTH action. We used amber codon suppression to generate a phosphorylated Ser162(pSer162)-PDZ2 variant. KD values determined by fluorescence anisotropy indicate that incorporation of pSer162 increased the binding affinity to the carboxy terminus of GRK6A 2-fold compared with WT PDZ2. Molecular dynamics simulations predict formation of an electrostatic network between pSer162 and Asp183 of PDZ2 and Arg at position −1 of the GRK6A PDZ-binding motif. Our results suggest that PDZ2 plays a regulatory role in PTH-sensitive NPT2A-mediated phosphate transport and phosphorylation of Ser162 in PDZ2 modulates the interaction with GRK6A.
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Affiliation(s)
- Maria Vistrup-Parry
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - W Bruce Sneddon
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Sofie Bach
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Peter A Friedman
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Tatyana Mamonova
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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9
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Mamonova T, Friedman PA. Noncanonical Sequences Involving NHERF1 Interaction with NPT2A Govern Hormone-Regulated Phosphate Transport: Binding Outside the Box. Int J Mol Sci 2021; 22:1087. [PMID: 33499384 PMCID: PMC7866199 DOI: 10.3390/ijms22031087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/27/2022] Open
Abstract
Na+/H+ exchange factor-1 (NHERF1), a multidomain PDZ scaffolding phosphoprotein, is required for the type II sodium-dependent phosphate cotransporter (NPT2A)-mediated renal phosphate absorption. Both PDZ1 and PDZ2 domains are involved in NPT2A-dependent phosphate uptake. Though harboring identical core-binding motifs, PDZ1 and PDZ2 play entirely different roles in hormone-regulated phosphate transport. PDZ1 is required for the interaction with the C-terminal PDZ-binding sequence of NPT2A (-TRL). Remarkably, phosphocycling at Ser290 distant from PDZ1, the penultimate step for both parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23) regulation, controls the association between NHERF1 and NPT2A. PDZ2 interacts with the C-terminal PDZ-recognition motif (-TRL) of G Protein-coupled Receptor Kinase 6A (GRK6A), and that promotes phosphorylation of Ser290. The compelling biological puzzle is how PDZ1 and PDZ2 with identical GYGF core-binding motifs specifically recognize distinct binding partners. Binding determinants distinct from the canonical PDZ-ligand interactions and located "outside the box" explain PDZ domain specificity. Phosphorylation of NHERF1 by diverse kinases and associated conformational changes in NHERF1 add more complexity to PDZ-binding diversity.
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Affiliation(s)
- Tatyana Mamonova
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA;
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10
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Durrani MK, Kang J. Thermodynamic analysis of the binding of p38 MAPK to substrate proteins. J Biol Chem 2020; 295:1366. [PMID: 32005643 DOI: 10.1074/jbc.l119.011911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Mehvish K Durrani
- Department of Biology, Valdosta State University, Valdosta, Georgia 31698
| | - Jonghoon Kang
- Department of Biology, Valdosta State University, Valdosta, Georgia 31698
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11
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Durrani MK, Kang J. Thermodynamic analysis of the binding of p38 MAPK to substrate proteins. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49892-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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12
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Janezic EM, Harris DA, Dinh D, Lee KS, Stewart A, Hinds TR, Hsu PL, Zheng N, Hague C. Scribble co-operatively binds multiple α 1D-adrenergic receptor C-terminal PDZ ligands. Sci Rep 2019; 9:14073. [PMID: 31575922 PMCID: PMC6773690 DOI: 10.1038/s41598-019-50671-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 09/17/2019] [Indexed: 01/17/2023] Open
Abstract
Many G protein-coupled receptors (GPCRs) are organized as dynamic macromolecular complexes in human cells. Unraveling the structural determinants of unique GPCR complexes may identify unique protein:protein interfaces to be exploited for drug development. We previously reported α1D-adrenergic receptors (α1D-ARs) – key regulators of cardiovascular and central nervous system function – form homodimeric, modular PDZ protein complexes with cell-type specificity. Towards mapping α1D-AR complex architecture, biolayer interferometry (BLI) revealed the α1D-AR C-terminal PDZ ligand selectively binds the PDZ protein scribble (SCRIB) with >8x higher affinity than known interactors syntrophin, CASK and DLG1. Complementary in situ and in vitro assays revealed SCRIB PDZ domains 1 and 4 to be high affinity α1D-AR PDZ ligand interaction sites. SNAP-GST pull-down assays demonstrate SCRIB binds multiple α1D-AR PDZ ligands via a co-operative mechanism. Structure-function analyses pinpoint R1110PDZ4 as a unique, critical residue dictating SCRIB:α1D-AR binding specificity. The crystal structure of SCRIB PDZ4 R1110G predicts spatial shifts in the SCRIB PDZ4 carboxylate binding loop dictate α1D-AR binding specificity. Thus, the findings herein identify SCRIB PDZ domains 1 and 4 as high affinity α1D-AR interaction sites, and potential drug targets to treat diseases associated with aberrant α1D-AR signaling.
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Affiliation(s)
- Eric M Janezic
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Dorathy-Ann Harris
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Diana Dinh
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Kyung-Soon Lee
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Aaron Stewart
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Thomas R Hinds
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Peter L Hsu
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA.,Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA
| | - Ning Zheng
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA.,Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA
| | - Chris Hague
- Department of Pharmacology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA.
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13
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Bhattacharya S, Stanley CB, Heller WT, Friedman PA, Bu Z. Dynamic structure of the full-length scaffolding protein NHERF1 influences signaling complex assembly. J Biol Chem 2019; 294:11297-11310. [PMID: 31171716 PMCID: PMC6643037 DOI: 10.1074/jbc.ra119.008218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 06/05/2019] [Indexed: 01/14/2023] Open
Abstract
The Na+/H+ exchange regulatory cofactor 1 (NHERF1) protein modulates the assembly and intracellular trafficking of several transmembrane G protein-coupled receptors (GPCRs) and ion transport proteins with the membrane-cytoskeleton adapter protein ezrin. Here, we applied solution NMR and small-angle neutron scattering (SANS) to structurally characterize full-length NHERF1 and disease-associated variants that are implicated in impaired phosphate homeostasis. Using NMR, we mapped the modular architecture of NHERF1, which is composed of two structurally-independent PDZ domains that are connected by a flexible, disordered linker. We observed that the ultra-long and disordered C-terminal tail of NHERF1 has a type 1 PDZ-binding motif that interacts weakly with the proximal, second PDZ domain to form a dynamically autoinhibited structure. Using ensemble-optimized analysis of SANS data, we extracted the molecular size distribution of structures from the extensive conformational space sampled by the flexible chain. Our results revealed that NHERF1 is a diffuse ensemble of variable PDZ domain configurations and a disordered C-terminal tail. The joint NMR/SANS data analyses of three disease variants (L110V, R153Q, and E225K) revealed significant differences in the local PDZ domain structures and in the global conformations compared with the WT protein. Furthermore, we show that the substitutions affect the affinity and kinetics of NHERF1 binding to ezrin and to a C-terminal peptide from G protein-coupled receptor kinase 6A (GRK6A). These findings provide important insight into the modulation of the intrinsic flexibility of NHERF1 by disease-associated point mutations that alter the dynamic assembly of signaling complexes.
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Affiliation(s)
| | - Christopher B Stanley
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
| | - William T Heller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
| | - Peter A Friedman
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Zimei Bu
- Department of Chemistry and Biochemistry, City College of New York, New York, New York 10031
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