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Maranduca MA, Cozma CT, Clim A, Pinzariu AC, Tudorancea I, Popa IP, Lazar CI, Moscalu R, Filip N, Moscalu M, Constantin M, Scripcariu DV, Serban DN, Serban IL. The Molecular Mechanisms Underlying the Systemic Effects Mediated by Parathormone in the Context of Chronic Kidney Disease. Curr Issues Mol Biol 2024; 46:3877-3905. [PMID: 38785509 PMCID: PMC11120161 DOI: 10.3390/cimb46050241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/25/2024] Open
Abstract
Chronic kidney disease (CKD) stands as a prominent non-communicable ailment, significantly impacting life expectancy. Physiopathology stands mainly upon the triangle represented by parathormone-Vitamin D-Fibroblast Growth Factor-23. Parathormone (PTH), the key hormone in mineral homeostasis, is one of the less easily modifiable parameters in CKD; however, it stands as a significant marker for assessing the risk of complications. The updated "trade-off hypothesis" reveals that levels of PTH spike out of the normal range as early as stage G2 CKD, advancing it as a possible determinant of systemic damage. The present review aims to review the effects exhibited by PTH on several organs while linking the molecular mechanisms to the observed actions in the context of CKD. From a diagnostic perspective, PTH is the most reliable and accessible biochemical marker in CKD, but its trend bears a higher significance on a patient's prognosis rather than the absolute value. Classically, PTH acts in a dichotomous manner on bone tissue, maintaining a balance between formation and resorption. Under the uremic conditions of advanced CKD, the altered intestinal microbiota majorly tips the balance towards bone lysis. Probiotic treatment has proven reliable in animal models, but in humans, data are limited. Regarding bone status, persistently high levels of PTH determine a reduction in mineral density and a concurrent increase in fracture risk. Pharmacological manipulation of serum PTH requires appropriate patient selection and monitoring since dangerously low levels of PTH may completely inhibit bone turnover. Moreover, the altered mineral balance extends to the cardiovascular system, promoting vascular calcifications. Lastly, the involvement of PTH in the Renin-Angiotensin-Aldosterone axis highlights the importance of opting for the appropriate pharmacological agent should hypertension develop.
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Affiliation(s)
- Minela Aida Maranduca
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
| | - Cristian Tudor Cozma
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
| | - Andreea Clim
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
| | - Alin Constantin Pinzariu
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
| | - Ionut Tudorancea
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
| | - Irene Paula Popa
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
| | - Cristina Iuliana Lazar
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
| | - Roxana Moscalu
- Division of Cell Matrix Biology & Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, UK;
| | - Nina Filip
- Discipline of Biochemistry, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania;
| | - Mihaela Moscalu
- Department of Preventive Medicine and Interdisciplinarity, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania
| | - Mihai Constantin
- Internal Medicine Department, Faculty of Medicine, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania;
| | - Dragos Viorel Scripcariu
- Department of Surgery, Grigore T. Popa University of Medicine and Pharmacy, 16 University Str., 700115 Iasi, Romania;
| | - Dragomir Nicolae Serban
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
| | - Ionela Lacramioara Serban
- Discipline of Physiology, Department of Morpho-Functional Sciences II, Grigore T. Popa University of Medicine and Pharmacy, 700115 Iasi, Romania; (M.A.M.); (C.T.C.); (A.C.); (A.C.P.); (I.T.); (I.P.P.); (C.I.L.); (D.N.S.); (I.L.S.)
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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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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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Chen H, Ren W, Gao Z, Zeng M, Tang S, Xu F, Huang Y, Zhang L, Cui Y, Yang G, Qian H, Zhou W, Ouyang C, Gao X, Zhang J, Xiao Y, Zhao B, Wang J, Bian A, Li F, Wan H, Gao W, Wang X, Xing C, Zha X, Wang N. Effects of parathyroidectomy on plasma PTH fragments and heart rate variability in stage 5 chronic kidney disease patients. Ren Fail 2021; 43:890-899. [PMID: 34044733 PMCID: PMC8168729 DOI: 10.1080/0886022x.2021.1931318] [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] [Indexed: 12/15/2022] Open
Abstract
INTRODUCTION Circulating intact parathyroid hormone (iPTH) levels include full-length (1-84) PTH and long C-PTH fragments, but primarily (7-84) PTH, which have been reported to have antagonistic effects on the bones and kidneys. However, their effects on the cardiovascular system remain unclear. In this study, the relationships between the plasma PTH fragments levels and heart rate variability (HRV) in stage 5 chronic kidney disease (CKD5) patients are explored. Furthermore, the effects of parathyroidectomy (PTX) on the above indices are investigated. METHODS In this cross-sectional study, 164 healthy controls and 354 CKD5 patients, including 208 secondary hyperparathyroidism (SHPT) subgroup with PTX, were enrolled. Circulating (7-84) PTH levels were calculated by subtracting plasma (1-84) PTH levels from iPTH levels. The HRV parameters were measured using a 24-hour Holter. RESULTS The baseline levels of plasma iPTH, (1-84) PTH, and (7-84) PTH in the CKD5 patients were 930.40 (160.65, 1792.50) pg/mL, 448.60 (99.62, 850.45) pg/mL, and 468.20 (54.22, 922.55) pg/mL, respectively. In the CKD5 patients, plasma (1-84) PTH levels were independently correlated with the standard deviation of the normal-to-normal R-R intervals (SDNN) and the standard deviation of the five-minute average of the normal R-R intervals (SDANN). With a median follow up time of 6.50 months after PTX in the SHPT patients (n = 30), improved SDNN and SDANN markers were related with decreased (1-84) PTH levels. Furthermore, an improved SDNN was related with decreased (7-84) PTH levels. CONCLUSIONS The CKD5 patients' baseline (1-84) PTH levels were correlated with the SDNN and SDANN. After PTX, an improved SDNN was related with decreased (1-84) PTH and (7-84) PTH levels, while improved SDANN was related with decreased (1-84) PTH levels. No antagonistic effects of (1-84) PTH and (7-84) PTH on HRV were found in the CKD5 patients.
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Affiliation(s)
- Huimin Chen
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China.,Department of Nephrology, Taizhou People's Hospital, Taizhou, China
| | - Wenkai Ren
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Zhanhui Gao
- Department of Nephrology, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
| | - Ming Zeng
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Shaowen Tang
- Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Fangyan Xu
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Yaoyu Huang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Lina Zhang
- Department of Nephrology, Henan Provincial Key Laboratory of Kidney Disease and Immunology, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Ying Cui
- Department of Nephrology, Northern Jiangsu People's Hospital Affiliated to Yangzhou University, Yangzhou, China
| | - Guang Yang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Hanyang Qian
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Wenbin Zhou
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Chun Ouyang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China.,Department of Nephrology, Liyang Branch, Jiangsu Province Hospital, Liyang People's Hospital, Liyang, China
| | - Xueyan Gao
- Department of General Medicine, Geriatric Hospital of Nanjing Medical University, Nanjing, China
| | - Jing Zhang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Yujie Xiao
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Baiqiao Zhao
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Jing Wang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Anning Bian
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Fan Li
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Huiting Wan
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Wei Gao
- National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Xiaoyun Wang
- Department of Nephrology, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
| | - Changying Xing
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Xiaoming Zha
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Ningning Wang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
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Physical Activity-Dependent Regulation of Parathyroid Hormone and Calcium-Phosphorous Metabolism. Int J Mol Sci 2020; 21:ijms21155388. [PMID: 32751307 PMCID: PMC7432834 DOI: 10.3390/ijms21155388] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/09/2020] [Accepted: 07/23/2020] [Indexed: 12/14/2022] Open
Abstract
Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the effects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise. Altered PTH metabolism underlies hyperparathyroidism and hypoparathyroidism, the complications of which affect the organs involved in calcium and phosphorous metabolism (bone and kidney) and other body systems as well. Exercise affects PTH expression and secretion by altering the circulating levels of calcium and phosphate. In turn, PTH responds directly to exercise and exercise-induced myokines. Here, we review the main concepts of the regulation of PTH expression and secretion under physiological conditions, in acute and chronic exercise, and in relation to PTH-related disorders.
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Abstract
Parathyroid hormone is an essential regulator of extracellular calcium and phosphate. PTH enhances calcium reabsorption while inhibiting phosphate reabsorption in the kidneys, increases the synthesis of 1,25-dihydroxyvitamin D, which then increases gastrointestinal absorption of calcium, and increases bone resorption to increase calcium and phosphate. Parathyroid disease can be an isolated endocrine disorder or part of a complex syndrome. Genetic mutations can account for diseases of parathyroid gland formulation, dysregulation of parathyroid hormone synthesis or secretion, and destruction of the parathyroid glands. Over the years, a number of different options are available for the treatment of different types of parathyroid disease. Therapeutic options include surgical removal of hypersecreting parathyroid tissue, administration of parathyroid hormone, vitamin D, activated vitamin D, calcium, phosphate binders, calcium-sensing receptor, and vitamin D receptor activators to name a few. The accurate assessment of parathyroid hormone also provides essential biochemical information to properly diagnose parathyroid disease. Currently available immunoassays may overestimate or underestimate bioactive parathyroid hormone because of interferences from truncated parathyroid hormone fragments, phosphorylation of parathyroid hormone, and oxidation of amino acids of parathyroid hormone.
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Affiliation(s)
- Edward Ki Yun Leung
- Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, CA, United States; Department of Pathology, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States.
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Sato M, Aoki H, Nakamura T, Onodera S, Yamaguchi A, Saito A, Azuma T. Effects of intermittent treatment with parathyroid hormone (PTH) on osteoblastic differentiation and mineralization of mouse induced pluripotent stem cells in a 3D culture model. J Periodontal Res 2020; 55:734-743. [PMID: 32583900 DOI: 10.1111/jre.12762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/10/2020] [Accepted: 04/24/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND/OBJECTIVES PTH plays an important role in bone remodeling, and different actions have been reported depending on its administration method. iPSCs are promising as a cell source for regeneration of periodontal tissue due to their ability of proliferation and pluripotency. However, the effects of PTH on iPSCs remain mostly unknown. The purpose of this study was to investigate in vitro effects of parathyroid hormone (PTH) on osteoblastic differentiation of induced pluripotent stem cells (iPSCs) in a 3D culture model. MATERIALS AND METHODS Following embryoid body (EB) induction from mouse iPSCs (miPSCs), dissociated cells (miPS-EB-derived cells) were seeded onto atelocollagen sponge (ACS) in osteoblast differentiation medium (OBM). Cell-ACS constructs were divided into three groups: continuous treatment with human recombinant PTH (1-34) (PTH-C), intermittent PTH treatment (PTH-I) or OBM control. To confirm the expression of PTH receptor-1(PTH1R), the expression of Pth1r and cAMP production over time were assessed. Real-time PCR was used to assess the expression of genes encoding osterix (Sp7), runt-related transcription factor 2 (Runx2), collagen type 1 (Col1a1), and osteocalcin (Bglap) at different time points. Mineralization was assessed by von Kossa staining. Histochemical staining was used to analyze alkaline phosphatase (ALP) activity, and immunolocalization of SP7 and BGLAP was analyzed by confocal laser scanning microscopy (CLSM). RESULTS On days 7 and 14, expression of the Pth1r in miPS-EB-derived cells was increased in all groups. Production of cAMP, the second messenger of the PTH1R, tended to increase in the PTH-I group compared with PTH-C group on day 14. Expression of Col1a1 in the PTH-I group on day 14 was significantly higher than other groups. There was a time-dependent increase in the expression of Sp7 in all groups. On day 14, the expression level of Sp7 in the PTH-I group was significantly higher than other groups. In von Kossa staining, the PTH-I group showed higher level of staining compared with other groups on day 14, whereas the level was slightly attenuated in the PTH-C group. In histochemical staining, ALP-positive cells were significantly increased in the PTH-I group compared with other groups on day 14. In CLSM analysis, the numbers of SP7- and BGLAP-positive cells showed a gradual increase over time, and on day 14, a significantly greater SP7 expression was observed in the PTH-I group than other groups. CONCLUSION These results suggested that the intermittent PTH treatment promotes osteoblastic differentiation and mineralization of miPSCs in the ACS scaffold.
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Affiliation(s)
- Masahiro Sato
- Department of Periodontology, Tokyo Dental College, Tokyo, Japan
| | - Hideto Aoki
- Department of Periodontology, Tokyo Dental College, Tokyo, Japan.,Oral Health Science Center, Tokyo Dental College, Tokyo, Japan
| | - Takashi Nakamura
- Oral Health Science Center, Tokyo Dental College, Tokyo, Japan.,Department of Biochemistry, Tokyo Dental College, Tokyo, Japan
| | - Shoko Onodera
- Oral Health Science Center, Tokyo Dental College, Tokyo, Japan.,Department of Biochemistry, Tokyo Dental College, Tokyo, Japan
| | - Akira Yamaguchi
- Oral Health Science Center, Tokyo Dental College, Tokyo, Japan
| | - Atsushi Saito
- Department of Periodontology, Tokyo Dental College, Tokyo, Japan.,Oral Health Science Center, Tokyo Dental College, Tokyo, Japan
| | - Toshifumi Azuma
- Oral Health Science Center, Tokyo Dental College, Tokyo, Japan.,Department of Biochemistry, Tokyo Dental College, Tokyo, Japan
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Song GJ, Gupta DP, Rahman MH, Park HT, Al Ghouleh I, Bisello A, Lee MG, Park JY, Park HH, Jun JH, Chung KW, Choi BO, Suk K. Loss-of-function of EBP50 is a new cause of hereditary peripheral neuropathy: EBP50 functions in peripheral nerve system. Glia 2020; 68:1794-1809. [PMID: 32077526 DOI: 10.1002/glia.23805] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 12/12/2022]
Abstract
Finding causative genetic mutations is important in the diagnosis and treatment of hereditary peripheral neuropathies. This study was conducted to find new genes involved in the pathophysiology of hereditary peripheral neuropathy. We identified a new mutation in the EBP50 gene, which is co-segregated with neuropathic phenotypes, including motor and sensory deficit in a family with Charcot-Marie-Tooth disease. EBP50 is known to be important for the formation of microvilli in epithelial cells, and the discovery of this gene mutation allowed us to study the function of EBP50 in the nervous system. EBP50 was strongly expressed in the nodal and paranodal regions of sciatic nerve fibers, where Schwann cell microvilli contact the axolemma, and at the growth tips of primary Schwann cells. In addition, EBP50 expression was decreased in mouse models of peripheral neuropathy. Knockout mice were used to study EBP50 function in the peripheral nervous system. Interestingly motor function deficit and abnormal histology of nerve fibers were observed in EBP50+/- heterozygous mice at 12 months of age, but not 3 months. in vitro studies using Schwann cells showed that NRG1-induced AKT activation and migration were significantly reduced in cells overexpressing the I325V mutant of EBP50 or cells with knocked-down EBP50 expression. In conclusion, we show for the first time that loss of function due to EBP50 gene deficiency or mutation can cause peripheral neuropathy.
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Affiliation(s)
- Gyun Jee Song
- Department of Medical Science, Institute for Bio-Medical Convergence, Catholic Kwandong University, International St. Mary's Hospital, Incheon, Republic of Korea
| | - Deepak Prasad Gupta
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Md Habibur Rahman
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Hwan Tae Park
- Department of Molecular Neuroscience, College of Medicine, Dong-A University, Busan, Republic of Korea
| | - Imad Al Ghouleh
- Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Alessandro Bisello
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Maan-Gee Lee
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Jae-Yong Park
- School of Biosystems and Biomedical Sciences, College of Health Sciences, Korea University, Seoul, Republic of Korea
| | - Hyun Ho Park
- College of Pharmacy, Chung-Ang University, Seoul, Republic of Korea
| | - Jin Hyun Jun
- Department of Senior Healthcare, BK21 Plus Program, Graduate School of Eulji University, Department of Biomedical Laboratory Science, College of Health Science, Eulji University, Seongnam, Republic of Korea
| | - Ki Wha Chung
- Department of Biological Sciences, Kongju National University, Gongju, Republic of Korea
| | - Byung-Ok Choi
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Kyoungho Suk
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 Plus KNU Biomedical Convergence Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
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9
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Abstract
Parathyroid hormone (PTH), PTH-related peptide (PTHrP), PTHR, and their cognate G protein-coupled receptor play defining roles in the regulation of extracellular calcium and phosphate metabolism and in controlling skeletal growth and repair. Acting through complex signaling mechanisms that in many instances proceed in a tissue-specific manner, precise control of these processes is achieved. A variety of direct and indirect disease processes, along with genetic anomalies, can cause these schemes to become dysfunctional. Here, we review the basic components of this regulatory network and present both the well-established elements and emerging findings and concepts with the overall objective to provide a framework for understanding the elementary aspects of how PTH and PTHrP behave and as a call to encourage further investigation that will yield more comprehensive understanding of the physiological and pathological steps at play, with a goal toward novel therapeutic interventions.
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10
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CCR5: Established paradigms and new frontiers for a 'celebrity' chemokine receptor. Cytokine 2019; 109:81-93. [PMID: 29903576 DOI: 10.1016/j.cyto.2018.02.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 02/14/2018] [Accepted: 02/16/2018] [Indexed: 01/04/2023]
Abstract
Because of the level of attention it received due to its role as the principal HIV coreceptor, CCR5 has been described as a 'celebrity' chemokine receptor. Here we describe the development of CCR5 inhibitory strategies that have been developed for HIV therapy and which are now additionally being considered for use in HIV prevention and cure. The wealth of CCR5-related tools that have been developed during the intensive investigation of CCR5 as an HIV drug target can now be turned towards the study of CCR5 as a model chemokine receptor. We also summarize what is currently known about the cell biology and pharmacology of CCR5, providing an update on new areas of investigation that have emerged in recent research. Finally, we discuss the potential of CCR5 as a drug target for diseases other than HIV, discussing the evidence linking CCR5 and its natural chemokine ligands with inflammatory diseases, particularly neuroinflammation, and certain cancers. These pathologies may provide new uses for the strategies for CCR5 blockade originally developed to combat HIV/AIDS.
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11
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Kritmetapak K, Pongchaiyakul C. Parathyroid Hormone Measurement in Chronic Kidney Disease: From Basics to Clinical Implications. Int J Nephrol 2019; 2019:5496710. [PMID: 31637056 PMCID: PMC6766083 DOI: 10.1155/2019/5496710] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/04/2019] [Indexed: 11/18/2022] Open
Abstract
Accurate measurement of parathyroid hormone (PTH) is crucial for therapeutic decision-making in patients with chronic kidney disease-mineral and bone disorder (CKD-MBD). The second-generation PTH assays, often referred to as "intact PTH" assays, are the current standard and most available assays in clinical practice. However, intact PTH assays measure both full-length biologically active PTH and heterogeneous PTH fragments in the circulation, providing the equivocal value of PTH measurement in patients with CKD-MBD. Due to the variability of PTH assays, preanalytical sample errors, and the phenomenon of end-organ PTH hyporesponsiveness, current CKD-MBD guidelines recommend a wide range for serum PTH targets (2-9 the upper normal limit of the intact PTH assay) in dialysis patients to diminish the risk of developing adynamic bone disease. Nevertheless, a sizeable proportion of CKD patients still experience renal osteodystrophy despite having serum PTH levels within the recommended range. The primary cause of this inconsistency is the analytical interference of various PTH fragments and oxidized PTH forms that considerably accumulate in CKD patients. Therefore, a new mass spectrometry-based assay, which is capable of specifically measuring the whole spectra of PTH fragments, can potentially improve diagnostic accuracy for renal osteodystrophy. However, the effects of different PTH fragments on bone metabolism, vascular calcification, and mortality in CKD patients warrant further research.
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Affiliation(s)
- Kittrawee Kritmetapak
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Chatlert Pongchaiyakul
- Division of Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
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12
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Pera T, Tompkins E, Katz M, Wang B, Deshpande DA, Weinman EJ, Penn RB. Specificity of NHERF1 regulation of GPCR signaling and function in human airway smooth muscle. FASEB J 2019; 33:9008-9016. [PMID: 31042404 PMCID: PMC6662985 DOI: 10.1096/fj.201900323r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 04/08/2019] [Indexed: 12/21/2022]
Abstract
Na+/H+ exchanger regulatory factor 1 (NHERF1; also known as ezrin-radixin-moesin-binding phosphoprotein 50) is a PSD-95, disc large, zona occludens-1 adapter that acts as a scaffold for signaling complexes and cytoskeletal-plasma membrane interactions. NHERF1 is crucial to β-2-adrenoceptor (β2AR)-mediated activation of cystic fibrosis transmembrane conductance regulator (CFTR) in epithelial cells, and NHERF1 has been proposed to mediate the recycling of internalized β2AR back to the cell membrane. In the current study, we assessed the role of NHERF1 in regulating cAMP-mediated signaling and immunomodulatory functions in airway smooth muscle (ASM). NHERF1 knockdown attenuated the induction of (protein kinase A) phospho-vasodilator-stimulated phosphoprotein (p-VASP) by isoproterenol (ISO), prostaglandin E2 (PGE2), or forskolin (FSK) as well as the induction of p-heat shock protein 20 after 4 h of stimulation with ISO and FSK. NHERF1 knockdown fully abrogated the ISO-, PGE2-, and FSK-induced IL-6 gene expression and cytokine production without affecting cAMP-mediated phosphodiesterase 4D (PDE4D) gene expression, phospho-cAMP response element-binding protein (p-CREB), and cAMP response element (CRE)-Luc, or PDGF-induced cyclin D1 expression. Interestingly, NHERF1 knockdown prevented ISO-induced chromatin-binding of the transcription factor CCAAT-enhancer-binding protein-β (c/EBPβ). c/EBPβ knockdown almost completely abrogated the cAMP-mediated IL-6 but not PDE4D gene expression. The differential regulation of cAMP-induced signaling and gene expression in our study indicates a role for NHERF1 in the compartmentalization of cAMP signaling in ASM.-Pera, T., Tompkins, E., Katz, M., Wang, B., Deshpande, D. A., Weinman, E. J., Penn, R. B. Specificity of NHERF1 regulation of GPCR signaling and function in human airway smooth muscle.
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Affiliation(s)
- Tonio Pera
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Eric Tompkins
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Michael Katz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Bin Wang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Deepak A. Deshpande
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Edward J. Weinman
- Department of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Raymond B. Penn
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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13
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Abstract
Parathyroid hormone (PTH) is the major secretory product of the parathyroid glands, and in hypocalcemic conditions, can enhance renal calcium reabsorption, increase active vitamin D production to increase intestinal calcium absorption, and mobilize calcium from bone by increasing turnover, mainly but not exclusively in cortical bone. PTH has therefore found clinical use as replacement therapy in hypoparathyroidism. PTH also may have a physiologic role in augmenting bone formation, particularly in trabecular and to some extent in cortical bone. This action has been applied to the clinic to provide anabolic therapy for osteoporosis.
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Affiliation(s)
- David Goltzman
- Department of Medicine and Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, Montreal, Quebec H4A 3J1, Canada; Departments of Medicine and of Physiology, McGill University, 845 Sherbrooke St West, Montreal, Quebec H3A 0B9, Canada.
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14
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Centonze M, Saponaro C, Mangia A. NHERF1 Between Promises and Hopes: Overview on Cancer and Prospective Openings. Transl Oncol 2018; 11:374-390. [PMID: 29455084 PMCID: PMC5852411 DOI: 10.1016/j.tranon.2018.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 01/02/2018] [Accepted: 01/05/2018] [Indexed: 02/07/2023] Open
Abstract
Na+/H+ exchanger regulatory factor 1 (NHERF1) is a scaffold protein, with two tandem PDZ domains and a carboxyl-terminal ezrin-binding (EB) region. This particular sticky structure is responsible for its interaction with different molecules to form multi-complexes that have a pivotal role in a lot of diseases. In particular, its involvement during carcinogenesis and cancer progression has been deeply analyzed in different tumors. The role of NHERF1 is not unique in cancer; its activity is connected to its subcellular localization. The literature data suggest that NHERF1 could be a new prognostic/predictive biomarker from breast cancer to hematological cancers. Furthermore, the high potential of this molecule as therapeutical target in different carcinomas is a new challenge for precision medicine. These evidences are part of a future view to improving patient clinical management, which should allow different tumor phenotypes to be treated with tailored therapies. This article reviews the biology of NHERF1, its engagement in different signal pathways and its involvement in different cancers, with a specific focus on breast cancer. It also considers NHERF1 potential role during inflammation related to most human cancers, designating new perspectives in the study of this "Janus-like" protein.
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Affiliation(s)
- Matteo Centonze
- Functional Biomorphology Laboratory, IRCCS-Istituto Tumori "Giovanni Paolo II", Bari, Italy
| | - Concetta Saponaro
- Functional Biomorphology Laboratory, IRCCS-Istituto Tumori "Giovanni Paolo II", Bari, Italy
| | - Anita Mangia
- Functional Biomorphology Laboratory, IRCCS-Istituto Tumori "Giovanni Paolo II", Bari, Italy.
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15
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Yang Y, Lei H, Qiang YW, Wang B. Ixazomib enhances parathyroid hormone-induced β-catenin/T-cell factor signaling by dissociating β-catenin from the parathyroid hormone receptor. Mol Biol Cell 2017; 28:1792-1803. [PMID: 28495797 PMCID: PMC5491187 DOI: 10.1091/mbc.e17-02-0096] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 12/15/2022] Open
Abstract
The proteasome inhibitor ixazomib (Izb) dissociates β-catenin from the PTH receptor to enhance PTH stimulation of β-catenin/TCF signaling through the cAMP/PKA signaling pathway. These findings provide a rationale for the use of Izb as an adjunct in the treatment of osteoporosis with PTH. The anabolic action of PTH in bone is mostly mediated by cAMP/PKA and Wnt-independent activation of β-catenin/T-cell factor (TCF) signaling. β-Catenin switches the PTH receptor (PTHR) signaling from cAMP/PKA to PLC/PKC activation by binding to the PTHR. Ixazomib (Izb) was recently approved as the first orally administered proteasome inhibitor for the treatment of multiple myeloma; it acts in part by inhibition of pathological bone destruction. Proteasome inhibitors were reported to stabilize β-catenin by the ubiquitin-proteasome pathway. However, how Izb affects PTHR activation to regulate β-catenin/TCF signaling is poorly understood. In the present study, using CRISPR/Cas9 genome-editing technology, we show that Izb reverses β-catenin–mediated PTHR signaling switch and enhances PTH-induced cAMP generation and cAMP response element–luciferase activity in osteoblasts. Izb increases active forms of β-catenin and promotes β-catenin translocation, thereby dissociating β-catenin from the PTHR at the plasma membrane. Furthermore, Izb facilitates PTH-stimulated GSK3β phosphorylation and β-catenin phosphorylation. Thus Izb enhances PTH stimulation of β-catenin/TCF signaling via cAMP-dependent activation, and this effect is due to its separating β-catenin from the PTHR. These findings provide evidence that Izb may be used to improve the therapeutic efficacy of PTH for the treatment of osteoporosis and other resorptive bone diseases.
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Affiliation(s)
- Yanmei Yang
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107
| | - Hong Lei
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107.,College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, China
| | - Ya-Wei Qiang
- Myeloma Institute, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | - Bin Wang
- Center for Translational Medicine, Department of Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107
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16
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Bastepe M, Turan S, He Q. Heterotrimeric G proteins in the control of parathyroid hormone actions. J Mol Endocrinol 2017; 58:R203-R224. [PMID: 28363951 PMCID: PMC5650080 DOI: 10.1530/jme-16-0221] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 02/17/2017] [Indexed: 12/17/2022]
Abstract
Parathyroid hormone (PTH) is a key regulator of skeletal physiology and calcium and phosphate homeostasis. It acts on bone and kidney to stimulate bone turnover, increase the circulating levels of 1,25 dihydroxyvitamin D and calcium and inhibit the reabsorption of phosphate from the glomerular filtrate. Dysregulated PTH actions contribute to or are the cause of several endocrine disorders. This calciotropic hormone exerts its actions via binding to the PTH/PTH-related peptide receptor (PTH1R), which couples to multiple heterotrimeric G proteins, including Gs and Gq/11 Genetic mutations affecting the activity or expression of the alpha-subunit of Gs, encoded by the GNAS complex locus, are responsible for several human diseases for which the clinical findings result, at least partly, from aberrant PTH signaling. Here, we review the bone and renal actions of PTH with respect to the different signaling pathways downstream of these G proteins, as well as the disorders caused by GNAS mutations.
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Affiliation(s)
- Murat Bastepe
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Serap Turan
- Department of Pediatric EndocrinologyMarmara University School of Medicine, Istanbul, Turkey
| | - Qing He
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
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17
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Callaway DJE, Matsui T, Weiss T, Stingaciu LR, Stanley CB, Heller WT, Bu Z. Controllable Activation of Nanoscale Dynamics in a Disordered Protein Alters Binding Kinetics. J Mol Biol 2017; 429:987-998. [PMID: 28285124 DOI: 10.1016/j.jmb.2017.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 02/04/2017] [Accepted: 03/02/2017] [Indexed: 01/03/2023]
Abstract
The phosphorylation of specific residues in a flexible disordered activation loop yields precise control of signal transduction. One paradigm is the phosphorylation of S339/S340 in the intrinsically disordered tail of the multi-domain scaffolding protein NHERF1, which affects the intracellular localization and trafficking of NHERF1 assembled signaling complexes. Using neutron spin echo spectroscopy (NSE), we show salt-concentration-dependent excitation of nanoscale motion at the tip of the C-terminal tail in the phosphomimic S339D/S340D mutant. The "tip of the whip" that is unleashed is near the S339/S340 phosphorylation site and flanks the hydrophobic Ezrin-binding motif. The kinetic association rate constant of the binding of the S339D/S340D mutant to the FERM domain of Ezrin is sensitive to buffer salt concentration, correlating with the excited nanoscale dynamics. The results suggest that electrostatics modulates the activation of nanoscale dynamics of an intrinsically disordered protein, controlling the binding kinetics of signaling partners. NSE can pinpoint the nanoscale dynamics changes in a highly specific manner.
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Affiliation(s)
- David J E Callaway
- Department of Chemistry and Biochemistry, City College of New York, CUNY, New York, NY 10031, USA.
| | - Tsutomu Matsui
- Stanford Synchrotron Radiation Light Source, Menlo Park, CA 94025, USA
| | - Thomas Weiss
- Stanford Synchrotron Radiation Light Source, Menlo Park, CA 94025, USA
| | - Laura R Stingaciu
- Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at SNS, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Christopher B Stanley
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - William T Heller
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Zimei Bu
- Department of Chemistry and Biochemistry, City College of New York, CUNY, New York, NY 10031, USA.
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18
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Lim HC, Jou TS. Ras-activated RSK1 phosphorylates EBP50 to regulate its nuclear localization and promote cell proliferation. Oncotarget 2016; 7:10283-96. [PMID: 26862730 PMCID: PMC4891120 DOI: 10.18632/oncotarget.7184] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/25/2016] [Indexed: 11/25/2022] Open
Abstract
Differential subcellular localization of EBP50 leads to its controversial role in cancer biology either as a tumor suppressor when it resides at the membrane periphery, or a tumor facilitator at the nucleus. However, the mechanism behind nuclear localization of EBP50 remains unclear. A RNA interference screening identified the downstream effector of the Ras-ERK cascade, RSK1, as the molecule unique for nuclear transport of EBP50. RSK1 binds to EBP50 and phosphorylates it at a conserved threonine residue at position 156 (T156) under the regulation of growth factor. Mutagenesis experiments confirmed the significance of T156 residue in nuclear localization of EBP50, cellular proliferation, and oncogenic transformation. Our study sheds light on a possible therapeutic strategy targeting at this aberrant nuclear expression of EBP50 without affecting the normal physiological function of EBP50 at other subcellular localization.
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Affiliation(s)
- Hooi Cheng Lim
- Graduate Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan
| | - Tzuu-Shuh Jou
- Graduate Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Clinical Medicine, National Taiwan University, Taipei, Taiwan
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19
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McGarvey JC, Xiao K, Bowman SL, Mamonova T, Zhang Q, Bisello A, Sneddon WB, Ardura JA, Jean-Alphonse F, Vilardaga JP, Puthenveedu MA, Friedman PA. Actin-Sorting Nexin 27 (SNX27)-Retromer Complex Mediates Rapid Parathyroid Hormone Receptor Recycling. J Biol Chem 2016; 291:10986-1002. [PMID: 27008860 DOI: 10.1074/jbc.m115.697045] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Indexed: 01/14/2023] Open
Abstract
The G protein-coupled parathyroid hormone receptor (PTHR) regulates mineral-ion homeostasis and bone remodeling. Upon parathyroid hormone (PTH) stimulation, the PTHR internalizes into early endosomes and subsequently traffics to the retromer complex, a sorting platform on early endosomes that promotes recycling of surface receptors. The C terminus of the PTHR contains a type I PDZ ligand that binds PDZ domain-containing proteins. Mass spectrometry identified sorting nexin 27 (SNX27) in isolated endosomes as a PTHR binding partner. PTH treatment enriched endosomal PTHR. SNX27 contains a PDZ domain and serves as a cargo selector for the retromer complex. VPS26, VPS29, and VPS35 retromer subunits were isolated with PTHR in endosomes from cells stimulated with PTH. Molecular dynamics and protein binding studies establish that PTHR and SNX27 interactions depend on the PDZ recognition motif in PTHR and the PDZ domain of SNX27. Depletion of either SNX27 or VPS35 or actin depolymerization decreased the rate of PTHR recycling following agonist stimulation. Mutating the PDZ ligand of PTHR abolished the interaction with SNX27 but did not affect the overall rate of recycling, suggesting that PTHR may directly engage the retromer complex. Coimmunoprecipitation and overlay experiments show that both intact and mutated PTHR bind retromer through the VPS26 protomer and sequentially assemble a ternary complex with PTHR and SNX27. SNX27-independent recycling may involve N-ethylmaleimide-sensitive factor, which binds both PDZ intact and mutant PTHRs. We conclude that PTHR recycles rapidly through at least two pathways, one involving the ASRT complex of actin, SNX27, and retromer and another possibly involving N-ethylmaleimide-sensitive factor.
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Affiliation(s)
- Jennifer C McGarvey
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - Kunhong Xiao
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - Shanna L Bowman
- the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Tatyana Mamonova
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - Qiangmin Zhang
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - Alessandro Bisello
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - W Bruce Sneddon
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - Juan A Ardura
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - Frederic Jean-Alphonse
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - Jean-Pierre Vilardaga
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and
| | - Manojkumar A Puthenveedu
- the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Peter A Friedman
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, and the Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
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20
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Abstract
PTH and Vitamin D are two major regulators of mineral metabolism. They play critical roles in the maintenance of calcium and phosphate homeostasis as well as the development and maintenance of bone health. PTH and Vitamin D form a tightly controlled feedback cycle, PTH being a major stimulator of vitamin D synthesis in the kidney while vitamin D exerts negative feedback on PTH secretion. The major function of PTH and major physiologic regulator is circulating ionized calcium. The effects of PTH on gut, kidney, and bone serve to maintain serum calcium within a tight range. PTH has a reciprocal effect on phosphate metabolism. In contrast, vitamin D has a stimulatory effect on both calcium and phosphate homeostasis, playing a key role in providing adequate mineral for normal bone formation. Both hormones act in concert with the more recently discovered FGF23 and klotho, hormones involved predominantly in phosphate metabolism, which also participate in this closely knit feedback circuit. Of great interest are recent studies demonstrating effects of both PTH and vitamin D on the cardiovascular system. Hyperparathyroidism and vitamin D deficiency have been implicated in a variety of cardiovascular disorders including hypertension, atherosclerosis, vascular calcification, and kidney failure. Both hormones have direct effects on the endothelium, heart, and other vascular structures. How these effects of PTH and vitamin D interface with the regulation of bone formation are the subject of intense investigation.
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Affiliation(s)
- Syed Jalal Khundmiri
- Department of Medicine, University of Louisville, Louisville, Kentucky, USA
- Department of Physiology and Biophysics, University of Louisville, Louisville, Kentucky, USA
| | - Rebecca D. Murray
- Department of Medicine, University of Louisville, Louisville, Kentucky, USA
- Department of Physiology and Biophysics, University of Louisville, Louisville, Kentucky, USA
| | - Eleanor Lederer
- Department of Medicine, University of Louisville, Louisville, Kentucky, USA
- Department of Physiology and Biophysics, University of Louisville, Louisville, Kentucky, USA
- Robley Rex VA Medical Center, University of Louisville, Louisville, Kentucky, USA
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21
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Chan ASM, Clairfeuille T, Landao-Bassonga E, Kinna G, Ng PY, Loo LS, Cheng TS, Zheng M, Hong W, Teasdale RD, Collins BM, Pavlos NJ. Sorting nexin 27 couples PTHR trafficking to retromer for signal regulation in osteoblasts during bone growth. Mol Biol Cell 2016; 27:1367-82. [PMID: 26912788 PMCID: PMC4831889 DOI: 10.1091/mbc.e15-12-0851] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/10/2016] [Indexed: 12/26/2022] Open
Abstract
The parathyroid hormone 1 receptor (PTHR) is central to the process of bone formation and remodeling. PTHR signaling requires receptor internalization into endosomes, which is then terminated by recycling or degradation. Here we show that sorting nexin 27 (SNX27) functions as an adaptor that couples PTHR to the retromer trafficking complex. SNX27 binds directly to the C-terminal PDZ-binding motif of PTHR, wiring it to retromer for endosomal sorting. The structure of SNX27 bound to the PTHR motif reveals a high-affinity interface involving conserved electrostatic interactions. Mechanistically, depletion of SNX27 or retromer augments intracellular PTHR signaling in endosomes. Osteoblasts genetically lacking SNX27 show similar disruptions in PTHR signaling and greatly reduced capacity for bone mineralization, contributing to profound skeletal deficits in SNX27-knockout mice. Taken together, our data support a critical role for SNX27-retromer mediated transport of PTHR in normal bone development.
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Affiliation(s)
- Audrey S M Chan
- Cellular Orthopaedic Laboratory, School of Surgery, University of Western Australia, Nedlands 6009, Australia
| | - Thomas Clairfeuille
- Institute for Molecular Bioscience, University of Queensland, St. Lucia 4072, Australia
| | - Euphemie Landao-Bassonga
- Cellular Orthopaedic Laboratory, School of Surgery, University of Western Australia, Nedlands 6009, Australia
| | - Genevieve Kinna
- Institute for Molecular Bioscience, University of Queensland, St. Lucia 4072, Australia
| | - Pei Ying Ng
- Cellular Orthopaedic Laboratory, School of Surgery, University of Western Australia, Nedlands 6009, Australia
| | - Li Shen Loo
- Institute of Molecular and Cell Biology, A*STAR, Singapore 138673
| | - Tak Sum Cheng
- Cellular Orthopaedic Laboratory, School of Surgery, University of Western Australia, Nedlands 6009, Australia
| | - Minghao Zheng
- Cellular Orthopaedic Laboratory, School of Surgery, University of Western Australia, Nedlands 6009, Australia
| | - Wanjin Hong
- Institute of Molecular and Cell Biology, A*STAR, Singapore 138673
| | - Rohan D Teasdale
- Institute for Molecular Bioscience, University of Queensland, St. Lucia 4072, Australia
| | - Brett M Collins
- Institute for Molecular Bioscience, University of Queensland, St. Lucia 4072, Australia
| | - Nathan J Pavlos
- Cellular Orthopaedic Laboratory, School of Surgery, University of Western Australia, Nedlands 6009, Australia
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22
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Venot Q, Delaunay JL, Fouassier L, Delautier D, Falguières T, Housset C, Maurice M, Aït-Slimane T. A PDZ-Like Motif in the Biliary Transporter ABCB4 Interacts with the Scaffold Protein EBP50 and Regulates ABCB4 Cell Surface Expression. PLoS One 2016; 11:e0146962. [PMID: 26789121 PMCID: PMC4720445 DOI: 10.1371/journal.pone.0146962] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 12/23/2015] [Indexed: 12/11/2022] Open
Abstract
ABCB4/MDR3, a member of the ABC superfamily, is an ATP-dependent phosphatidylcholine translocator expressed at the canalicular membrane of hepatocytes. Defects in the ABCB4 gene are associated with rare biliary diseases. It is essential to understand the mechanisms of its canalicular membrane expression in particular for the development of new therapies. The stability of several ABC transporters is regulated through their binding to PDZ (PSD95/DglA/ZO-1) domain-containing proteins. ABCB4 protein ends by the sequence glutamine-asparagine-leucine (QNL), which shows some similarity to PDZ-binding motifs. The aim of our study was to assess the potential role of the QNL motif on the surface expression of ABCB4 and to determine if PDZ domain-containing proteins are involved. We found that truncation of the QNL motif decreased the stability of ABCB4 in HepG2-transfected cells. The deleted mutant ABCB4-ΔQNL also displayed accelerated endocytosis. EBP50, a PDZ protein highly expressed in the liver, strongly colocalized and coimmunoprecipitated with ABCB4, and this interaction required the QNL motif. Down-regulation of EBP50 by siRNA or by expression of an EBP50 dominant-negative mutant caused a significant decrease in the level of ABCB4 protein expression, and in the amount of ABCB4 localized at the canalicular membrane. Interaction of ABCB4 with EBP50 through its PDZ-like motif plays a critical role in the regulation of ABCB4 expression and stability at the canalicular plasma membrane.
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Affiliation(s)
- Quitterie Venot
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Jean-Louis Delaunay
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Laura Fouassier
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Danièle Delautier
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Thomas Falguières
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Chantal Housset
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Centre de Référence Maladies Rares Maladies Inflammatoires des Voies Biliaires & Service d’Hépatologie, Paris, France
| | - Michèle Maurice
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Tounsia Aït-Slimane
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
- * E-mail:
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Gardella TJ, Vilardaga JP. International Union of Basic and Clinical Pharmacology. XCIII. The parathyroid hormone receptors--family B G protein-coupled receptors. Pharmacol Rev 2015; 67:310-37. [PMID: 25713287 DOI: 10.1124/pr.114.009464] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The type-1 parathyroid hormone receptor (PTHR1) is a family B G protein-coupled receptor (GPCR) that mediates the actions of two polypeptide ligands; parathyroid hormone (PTH), an endocrine hormone that regulates the levels of calcium and inorganic phosphate in the blood by acting on bone and kidney, and PTH-related protein (PTHrP), a paracrine-factor that regulates cell differentiation and proliferation programs in developing bone and other tissues. The type-2 parathyroid hormone receptor (PTHR2) binds a peptide ligand, called tuberoinfundibular peptide-39 (TIP39), and while the biologic role of the PTHR2/TIP39 system is not as defined as that of the PTHR1, it likely plays a role in the central nervous system as well as in spermatogenesis. Mechanisms of action at these receptors have been explored through a variety of pharmacological and biochemical approaches, and the data obtained support a basic "two-site" mode of ligand binding now thought to be used by each of the family B peptide hormone GPCRs. Recent crystallographic studies on the family B GPCRs are providing new insights that help to further refine the specifics of the overall receptor architecture and modes of ligand docking. One intriguing pharmacological finding for the PTHR1 is that it can form surprisingly stable complexes with certain PTH/PTHrP ligand analogs and thereby mediate markedly prolonged cell signaling responses that persist even when the bulk of the complexes are found in internalized vesicles. The PTHR1 thus appears to be able to activate the Gα(s)/cAMP pathway not only from the plasma membrane but also from the endosomal domain. The cumulative findings could have an impact on efforts to develop new drug therapies for the PTH receptors.
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Affiliation(s)
- Thomas J Gardella
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts (T.J.G.); and Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (J.-P.V.)
| | - Jean-Pierre Vilardaga
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts (T.J.G.); and Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (J.-P.V.)
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Andressen KW, Manfra O, Brevik CH, Ulsund AH, Vanhoenacker P, Levy FO, Krobert KA. The atypical antipsychotics clozapine and olanzapine promote down-regulation and display functional selectivity at human 5-HT7 receptors. Br J Pharmacol 2015; 172:3846-60. [PMID: 25884989 PMCID: PMC4523340 DOI: 10.1111/bph.13169] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 04/01/2015] [Accepted: 04/14/2015] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Classically, ligands of GPCRs have been classified primarily upon their affinity and efficacy to activate a signal transduction pathway. Recent reports indicate that the efficacy of a particular ligand can vary depending on the receptor-mediated response measured (e.g. activating G proteins, other downstream responses, internalization). Previously, we reported that inverse agonists induce both homo- and heterologous desensitization, similar to agonist stimulation, at the Gs -coupled 5-HT7 receptor. The primary objective of this study was to determine whether different inverse agonists at the 5-HT7 receptor also induce internalization and/or degradation of 5-HT7 receptors. EXPERIMENTAL APPROACH HEK293 cells expressing 5-HT7(a, b or d) receptors were pre-incubated with 5-HT, clozapine, olanzapine, mesulergine or SB269970 and their effects upon receptor density, AC activity, internalization, recruitment of β-arrestins and lysosomal trafficking were measured. KEY RESULTS The agonist 5-HT and three out of four inverse agonists tested increased internalization independently of β-arrestin recruitment. Among these, only the atypical antipsychotics clozapine and olanzapine promoted lysosomal sorting and reduced 5-HT7 receptor density (∼60% reduction within 24 h). Inhibition of lysosomal degradation with chloroquine blocked the clozapine- and olanzapine-induced down-regulation of 5-HT7 receptors. Incubation with SB269970 decreased both 5-HT7(b) constitutive internalization and receptor density but increased 5-HT7(d) receptor density, indicating differential ligand regulation among the 5-HT7 splice variants. CONCLUSIONS AND IMPLICATIONS Taken together, we found that various ligands differentially activate regulatory processes governing receptor internalization and degradation in addition to signal transduction. Thus, these data extend our understanding of functional selectivity at the 5-HT7 receptor.
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Affiliation(s)
- K W Andressen
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - O Manfra
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - C H Brevik
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - A H Ulsund
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - P Vanhoenacker
- Laboratory of Eukaryotic Gene Expression and Signal Transduction, Ghent University, Ghent, Belgium.,Intrexon ActoBiotics N.V., Technologiepark 4, Zwijnaarde, Belgium
| | - F O Levy
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - K A Krobert
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, Faculty of Medicine, University of Oslo, Oslo, Norway
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Polyzos SA, Makras P, Efstathiadou Z, Anastasilakis AD. Investigational parathyroid hormone receptor analogs for the treatment of osteoporosis. Expert Opin Investig Drugs 2014; 24:145-57. [PMID: 25316089 DOI: 10.1517/13543784.2015.973021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Intermittent parathyroid hormone (PTH) administration, acting through multiple signaling pathways, exerts an osteoanabolic effect on the skeleton that surpasses the effect of other antiosteoporotic agents. However, its efficacy is limited by the coupling effect and relatively common adverse events. Thus, the development of more sophisticated PTH receptor analogs seems imperative. AREAS COVERED In this review, the authors summarize the role of PTH signaling pathway in bone remodeling. The authors also summarize investigational analogs targeting this pathway, which may be potential treatments for osteoporosis. EXPERT OPINION β-arrestins are multifunctional cytoplasmic molecules that are decisive for regulating intracellular PTH signaling. Recently, in preclinical studies, arrestin analogs have achieved the anabolic bone effect of PTH without an accompanying increase in bone resorption. However, it is not yet known whether these analogs have adverse effects and there are no clinical data for their efficacy to date. On the other hand, several molecules derived either from PTH and PTH-related protein (PTHrP) molecules have been developed. Alternative routes of PTH 1 - 34 delivery (oral, transdermal), the PTH analog ostabolin and the N-terminal PTHrP analogs PTHrP 1 - 36 and abaloparatide, have recently been or are currently being tested in clinical trials and are more likely to become available for use in the near future.
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Affiliation(s)
- Stergios A Polyzos
- Harvard Medical School, Beth Israel Deaconess Medical Center, Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine , Boston, MA , USA
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26
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Kopic S, Geibel JP. Gastric acid, calcium absorption, and their impact on bone health. Physiol Rev 2013; 93:189-268. [PMID: 23303909 DOI: 10.1152/physrev.00015.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.
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Affiliation(s)
- Sascha Kopic
- Department of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
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27
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van der Lee MMC, Verkaar F, Wat JWY, van Offenbeek J, Timmerman M, Voorneveld L, van Lith LHCJ, Zaman GJR. β-Arrestin-biased signaling of PTH analogs of the type 1 parathyroid hormone receptor. Cell Signal 2012; 25:527-38. [PMID: 23159578 DOI: 10.1016/j.cellsig.2012.11.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 11/09/2012] [Accepted: 11/09/2012] [Indexed: 01/08/2023]
Abstract
Parathyroid hormone (PTH) is an anabolic agent that mediates bone formation through activation of the Gα(s)-, Gα(q)- and β-arrestin-coupled parathyroid hormone receptor type 1 (PTH1R). Pharmacological evidence based on the effect of PTH(7-34), a PTH derivative that is said to preferentially activate β-arrestin signaling through PTH1R, suggests that PTH1R-activated β-arrestin signaling mediates anabolic effects on bone. Here, we performed a thorough evaluation of PTH(7-34) signaling behaviour using quantitative assays for β-arrestin recruitment, Gα(s)- and Gα(q)-signaling. We found that PTH(7-34) inhibited PTH-induced cAMP accumulation, but was unable to induce β-arrestin recruitment, PTH1R internalization and ERK1/2 phosphorylation in HEK293, CHO and U2OS cells. Thus, the β-arrestin bias of PTH(7-34) is not apparent in every cell type examined, suggesting that correlating in vivo effects of PTH(7-34) to in vitro pharmacology should be done with caution.
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28
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Jayasundar JJ, Ju JH, He L, Liu D, Meilleur F, Zhao J, Callaway DJE, Bu Z. Open conformation of ezrin bound to phosphatidylinositol 4,5-bisphosphate and to F-actin revealed by neutron scattering. J Biol Chem 2012; 287:37119-33. [PMID: 22927432 PMCID: PMC3481312 DOI: 10.1074/jbc.m112.380972] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 08/22/2012] [Indexed: 11/06/2022] Open
Abstract
Ezrin is a member of the ezrin-radixin-moesin family (ERM) of adapter proteins that are localized at the interface between the cell membrane and the cortical actin cytoskeleton, and they regulate a variety of cellular functions. The structure representing a dormant and closed conformation of an ERM protein has previously been determined by x-ray crystallography. Here, using contrast variation small angle neutron scattering, we reveal the structural changes of the full-length ezrin upon binding to the signaling lipid phosphatidylinositol 4,5-bisphosphate (PIP(2)) and to F-actin. Ezrin binding to F-actin requires the simultaneous binding of ezrin to PIP(2). Once bound to F-actin, the opened ezrin forms more extensive contacts with F-actin than generally depicted, suggesting a possible role of ezrin in regulating the interfacial structure and dynamics between the cell membrane and the underlying actin cytoskeleton. In addition, using gel filtration, we find that the conformational opening of ezrin in response to PIP(2) binding is cooperative, but the cooperativity is disrupted by a phospho-mimic mutation S249D in the 4.1-ezrin/radixin/moesin (FERM) domain of ezrin. Using surface plasmon resonance, we show that the S249D mutation weakens the binding affinity and changes the kinetics of 4.1-ERM to PIP(2) binding. The study provides the first structural view of the activated ezrin bound to PIP(2) and to F-actin.
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Affiliation(s)
| | - Jeong Ho Ju
- From the Department of Chemistry, City College of New York, New York, New York 10031
| | - Lilin He
- the Center for Structural Molecular Biology and Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
- the Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Dazhi Liu
- the Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Flora Meilleur
- the Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
- the Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, and
| | - Jinkui Zhao
- the Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - David J. E. Callaway
- From the Department of Chemistry, City College of New York, New York, New York 10031
- the New York University School of Medicine, New York, New York 10016
| | - Zimei Bu
- From the Department of Chemistry, City College of New York, New York, New York 10031
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29
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Guo J, Song L, Liu M, Mahon MJ. Fluorescent ligand-directed co-localization of the parathyroid hormone 1 receptor with the brush-border scaffold complex of the proximal tubule reveals hormone-dependent changes in ezrin immunoreactivity consistent with inactivation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:2243-53. [PMID: 23036889 DOI: 10.1016/j.bbamcr.2012.09.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 09/25/2012] [Accepted: 09/26/2012] [Indexed: 01/12/2023]
Abstract
Through binding to parathyroid hormone (PTH), PTH1R interacts with kidney-specific scaffold proteins, including the sodium hydrogen exchanger regulatory factors 1 and 2 (NHERFs), and ezrin. To facilitate in vivo localization, tetramethylrhodamine-labeled PTH (PTH-TMR) was used as a fluorescent probe. In mice, PTH-TMR localizes to luminal surfaces of tubular S1 segments that overlap PTH1R immunostaining, but does not directly overlap with megalin-specific antibodies. PTH-TMR staining directly overlaps with Npt2a in nascent, endocytic vesicles, marking the location of transporter regulation. PKA substrate antibodies display marked staining increases in segments labeled with PTH-TMR, demonstrating a functional effect. In the presence of secondary hyperparathyroidism, PTH-TMR staining is markedly reduced and shifts to co-localizing with megalin. At 15min post-injection, PTH-TMR-labeled vesicles do not co-localize with either NHERF or ezrin, suggesting PTH1R dissociation from the scaffold complex. At the 5min time point, PTH-TMR stains the base of microvilli where it localizes with both NHERF2 and ezrin, and only partially with NHERF1. Strikingly, the bulk of ezrin protein becomes undetectable with the polyclonal, CS3145 antibody, revealing a PTH-induced conformational change in the scaffold. A second ezrin antibody (3C12) is capable of detecting the altered ezrin protein. The CS3145 antibody only binds to the active form of ezrin and fails to recognize the inactive form, while the 3C12 reagent can detect either active or inactive ezrin. Here we show that the PTH1R is part of the ezrin scaffold complex and that acute actions of PTH suggest a rapid inactivation of ezrin in a spatially defined manner.
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Affiliation(s)
- Jun Guo
- Massachusetts General Hospital and Department of Medicine, Harvard Medical School, Boston, MA 02114, USA
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30
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Dupré DJ, Rola-Pleszczynski M, Stankova J. Rescue of internalization-defective platelet-activating factor receptor function by EBP50/NHERF1. J Cell Commun Signal 2012; 6:205-16. [PMID: 22878922 DOI: 10.1007/s12079-012-0175-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/01/2012] [Indexed: 12/20/2022] Open
Abstract
Platelet-activating factor (PAF) is a potent phospholipid mediator involved in specific disease states such as allergic asthma, atherosclerosis and psoriasis. The human PAF receptor (PAFR) is a member of the G protein-coupled receptor (GPCR) family. Following PAF stimulation, cells become rapidly desensitized; this refractory state can be maintained for hours and is dependent on PAFR phosphorylation, internalization and trafficking. EBP50/NHERF1 has been found to interact with a variety of proteins and these interactions are involved in a growing range of functions including the assembly of signalling complexes, receptor recycling and transport of proteins to the cell surface. Crucial roles of EBP50 in GPCR physiology include its involvement in internalization, recycling, and downregulation. We were interested in identifying the role of EBP50 in PAFR trafficking. Our results showed that EBP50 binds the PAFR in its basal state, while stimulation decreased the ratio of interaction between the two proteins. We also demonstrated that EBP50 could bind PAFR via its PDZ 2 domain. In addition, we studied the role of EBP50 in various functions of the PAFR such as PAF-induced inositol phosphate accumulation and receptor internalization: EBP50 decreased the WT PAFR response and rescued the function of internalization-deficient mutant receptors, as previously described for the arrestins and the GRKs. These results suggest new roles for EBP50, some of which could help understanding the complex formation after receptor activation.
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Affiliation(s)
- Denis J Dupré
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, 5850 College St., PO BOX 15000, Halifax, NS, B3H 4R2, Canada,
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Wang B, Means CK, Yang Y, Mamonova T, Bisello A, Altschuler DL, Scott JD, Friedman PA. Ezrin-anchored protein kinase A coordinates phosphorylation-dependent disassembly of a NHERF1 ternary complex to regulate hormone-sensitive phosphate transport. J Biol Chem 2012; 287:24148-63. [PMID: 22628548 PMCID: PMC3397842 DOI: 10.1074/jbc.m112.369405] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/19/2012] [Indexed: 12/14/2022] Open
Abstract
Congenital defects in the Na/H exchanger regulatory factor-1 (NHERF1) are linked to disordered phosphate homeostasis and skeletal abnormalities in humans. In the kidney, these mutations interrupt parathyroid hormone (PTH)-responsive sequestration of the renal phosphate transporter, Npt2a, with ensuing urinary phosphate wasting. We now report that NHERF1, a modular PDZ domain scaffolding protein, coordinates the assembly of an obligate ternary complex with Npt2a and the PKA-anchoring protein ezrin to facilitate PTH-responsive cAMP signaling events. Activation of ezrin-anchored PKA initiates NHERF1 phosphorylation to disassemble the ternary complex, release Npt2a, and thereby inhibit phosphate transport. Loss-of-function mutations stabilize an inactive NHERF1 conformation that we show is refractory to PKA phosphorylation and impairs assembly of the ternary complex. Compensatory mutations introduced in mutant NHERF1 re-establish the integrity of the ternary complex to permit phosphorylation of NHERF1 and rescue PTH action. These findings offer new insights into a novel macromolecular mechanism for the physiological action of a critical ternary complex, where anchored PKA coordinates the assembly and turnover of the Npt2a-NHERF1-ezrin complex.
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Affiliation(s)
- Bin Wang
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Chris K. Means
- the Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Yanmei Yang
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Tatyana Mamonova
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Alessandro Bisello
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Daniel L. Altschuler
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - John D. Scott
- the Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Peter A. Friedman
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
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Nisar SP, Cunningham M, Saxena K, Pope RJ, Kelly E, Mundell SJ. Arrestin scaffolds NHERF1 to the P2Y12 receptor to regulate receptor internalization. J Biol Chem 2012; 287:24505-15. [PMID: 22610101 DOI: 10.1074/jbc.m112.347104] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have recently shown in a patient with mild bleeding that the PDZ-binding motif of the platelet G protein-coupled P2Y(12) receptor (P2Y(12)R) is required for effective receptor traffic in human platelets. In this study we show for the first time that the PDZ motif-binding protein NHERF1 exerts a major role in potentiating G protein-coupled receptor (GPCR) internalization. NHERF1 interacts with the C-tail of the P2Y(12)R and unlike many other GPCRs, NHERF1 interaction is required for effective P2Y(12)R internalization. In vitro and prior to agonist stimulation P2Y(12)R/NHERF1 interaction requires the intact PDZ binding motif of this receptor. Interestingly on receptor stimulation NHERF1 no longer interacts directly with the receptor but instead binds to the receptor via the endocytic scaffolding protein arrestin. These findings suggest a novel model by which arrestin can serve as an adaptor to promote NHERF1 interaction with a GPCR to facilitate effective NHERF1-dependent receptor internalization.
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Affiliation(s)
- Shaista P Nisar
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Briston BS8 1TD, United Kingdom
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D'Amour P. Acute and chronic regulation of circulating PTH: significance in health and in disease. Clin Biochem 2012; 45:964-9. [PMID: 22569597 DOI: 10.1016/j.clinbiochem.2012.04.029] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 04/16/2012] [Accepted: 04/26/2012] [Indexed: 11/26/2022]
Abstract
Circulating human parathyroid hormone (PTH) is immunoheterogenous. It is composed of 80% carboxyl-terminal (C) fragments and of 20% PTH(1-84). This composition contrasts with the biological activity of the hormone, which is only related to PTH(1-84), creating a paradox between circulating PTH composition and PTH bioactivity. PTH molecular forms are either secreted by the parathyroid glands or generated by the peripheral metabolism of PTH(1-84) in the liver. The kidney has a major role in the disposal of C-PTH fragments. Secretion of PTH molecular forms by the parathyroid glands is highly regulated under a variety of clinical conditions, suggesting that C-PTH fragments could exert some biological effects of their own. Recent data suggest that C-PTH fragments can exert biological actions opposite to those of PTH(1-84) by acting on a C-PTH receptor not yet cloned. They can decrease calcium concentration, phosphate excretion, bone resorption and 1,25(OH)₂ synthesis. The clinical implications of this new concept are reviewed.
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Affiliation(s)
- Pierre D'Amour
- Centre de Recherche, Centre Hospitalier de l'Université de Montréal-CRCHUM, Hôpital Saint-Luc, Department of Medicine, Université de Montréal, Montréal, Québec, Canada.
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Emami-Nemini A, Gohla A, Urlaub H, Lohse MJ, Klenk C. The Guanine Nucleotide Exchange Factor Vav2 Is a Negative Regulator of Parathyroid Hormone Receptor/Gq Signaling. Mol Pharmacol 2012; 82:217-25. [DOI: 10.1124/mol.112.078824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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Datta NS, Samra TA, Abou-Samra AB. Parathyroid hormone induces bone formation in phosphorylation-deficient PTHR1 knockin mice. Am J Physiol Endocrinol Metab 2012; 302:E1183-8. [PMID: 22338074 PMCID: PMC3361988 DOI: 10.1152/ajpendo.00380.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Activation of G protein-coupled receptors by agonists leads to receptor phosphorylation, internalization of ligand receptor complexes, and desensitization of hormonal response. The role of parathyroid hormone (PTH) receptor 1, PTHR1, is well characterized and known to regulate cellular responsiveness in vitro. However, the role of PTHR1 phosphorylation in bone formation is yet to be investigated. We have previously demonstrated that impaired internalization and sustained cAMP stimulation of phosphorylation-deficient (PD) PTHR1 leads to exaggerated cAMP response to subcutaneous PTH infusion in a PD knockin mouse model. To understand the physiological role of receptor internalization on PTH bone anabolic action, we examined bone parameters of wild-type (WT) and PD knockin female and male mice following PTH treatment. We found a decrease in total and diaphyseal bone mineral density in female but not in male PD mice compared with WT controls at 3-6 mo of age. This effect was attenuated at older age groups. PTH administration displayed increased bone volume and trabecular thickness in the vertebrae and distal femora of both WT and PD animals. These results suggest that PTHR1 phosphorylation does not play a major role in the anabolic action of PTH.
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Affiliation(s)
- Nabanita S Datta
- Wayne State Univ. School of Medicine, Dept. Internal Medicine/Endocrinology, 1107 Elliman Bldg., 421 E. Canfield Ave., Detroit, MI 48201, USA.
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Mamonova T, Kurnikova M, Friedman PA. Structural basis for NHERF1 PDZ domain binding. Biochemistry 2012; 51:3110-20. [PMID: 22429102 DOI: 10.1021/bi201213w] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The Na(+)/H(+) exchange regulatory factor-1 (NHERF1) is a scaffolding protein that possesses two tandem PDZ domains and a carboxy-terminal ezrin-binding domain (EBD). The parathyroid hormone receptor (PTHR), type II sodium-dependent phosphate cotransporter (Npt2a), and β2-adrenergic receptor (β2-AR), through their respective carboxy-terminal PDZ-recognition motifs, individually interact with NHERF1 forming a complex with one of the PDZ domains. In the basal state, NHERF1 adopts a self-inhibited conformation, in which its carboxy-terminal PDZ ligand interacts with PDZ2. We applied molecular dynamics (MD) simulations to uncover the structural and biochemical basis for the binding selectivity of NHERF1 PDZ domains. PDZ1 uniquely forms several contacts not present in PDZ2 that further stabilize PDZ1 interactions with target ligands. The binding free energy (ΔG) of PDZ1 and PDZ2 with the carboxy-terminal, five-amino acid residues that form the PDZ-recognition motif of PTHR, Npt2a, and β2-AR was calculated and compared with the calculated ΔG for the self-association of NHERF1. The results suggest that the interaction of the PTHR, β2-adrenergic, and Npt2a involves competition between NHERF1 PDZ domains and the target proteins. The binding of PDZ2 with PTHR may also compete with the self-inhibited conformation of NHERF1, thereby contributing to the stabilization of an active NHERF1 conformation.
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Affiliation(s)
- Tatyana Mamonova
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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Hayashi H, Naoi S, Nakagawa T, Nishikawa T, Fukuda H, Imajoh-Ohmi S, Kondo A, Kubo K, Yabuki T, Hattori A, Hirouchi M, Sugiyama Y. Sorting nexin 27 interacts with multidrug resistance-associated protein 4 (MRP4) and mediates internalization of MRP4. J Biol Chem 2012; 287:15054-65. [PMID: 22411990 DOI: 10.1074/jbc.m111.337931] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Multidrug resistance-associated protein 4 (MRP4/ABCC4) makes a vital contribution to the bodily distribution of drugs and endogenous compounds because of its cellular efflux abilities. However, little is known about the mechanism regulating its cell surface expression. MRP4 has a PDZ-binding motif, which is a potential sequence that modulates the membrane expression of MRP4 via interaction with PDZ adaptor proteins. To investigate this possible relationship, we performed GST pull-down assays and subsequent analysis with matrix-assisted laser desorption/ionization-time of flight mass spectrometry. This method identified sorting nexin 27 (SNX27) as the interacting PDZ adaptor protein with a PDZ-binding motif of MRP4. Its interaction was confirmed by a coimmunoprecipitation study using HEK293 cells. Knockdown of SNX27 by siRNA in HEK293 cells raised MRP4 expression on the plasma membrane, increased the extrusion of 6-[(14)C]mercaptopurine, an MRP4 substrate, and conferred resistance against 6-[(14)C]mercaptopurine. Cell surface biotinylation studies indicated that the inhibition of MRP4 internalization was responsible for these results. Immunocytochemistry and cell surface biotinylation studies using COS-1 cells showed that SNX27 localized to both the early endosome and the plasma membrane. These data suggest that SNX27 interacts with MRP4 near the plasma membrane and promotes endocytosis of MRP4 and thereby negatively regulates its cell surface expression and transport function.
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Affiliation(s)
- Hisamitsu Hayashi
- Laboratory of Molecular Pharmacokinetics, Department of Medical Pharmaceutics, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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Alonso V, Magyar CE, Wang B, Bisello A, Friedman PA. Ubiquitination-deubiquitination balance dictates ligand-stimulated PTHR sorting. J Bone Miner Res 2011; 26:2923-34. [PMID: 21898592 PMCID: PMC3222777 DOI: 10.1002/jbmr.494] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Parathyroid hormone receptors (PTHR) are promptly internalized upon stimulation by activating (PTH[1-84], PTH[1-34]) and non-activating (PTH[7-84], PTH[7-34]) ligands. Here, we characterized the mechanism regulating the sorting of internalized receptors between recycling and degradative pathways. PTHR recycles faster after challenge with PTH(1-34) than with PTH(7-34). PTHR recycling is complete by 2 h after PTH(1-34) stimulation, but incomplete at this time in cells treated with PTH(7-34). The slower and incomplete recycling induced by PTH(7-34) is due to proteasomal degradation. Both PTH(1-34) and PTH(7-34) induced PTHR polyubiquitination. Ubiquitination by PTH(1-34) was transient, whereas receptor ubiquitination after PTH(7-34) was sustained. PTH(1-34), but not PTH(7-34), induced expression of the PTHR-specific deubiquitinating enzyme USP2. Overexpression of USP2 prevented PTH(7-34)-induced PTHR degradation. We conclude that PTH(1-34) promotes coupled PTHR ubiquitination and deubiquitination, whereas PTH(7-34) activates only ubiquitination, thereby leading to PTHR downregulation. These findings may explain PTH resistance in diseases associated with elevated PTH(7-84) levels.
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Affiliation(s)
- Verónica Alonso
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Ardura JA, Wang B, Watkins SC, Vilardaga JP, Friedman PA. Dynamic Na+-H+ exchanger regulatory factor-1 association and dissociation regulate parathyroid hormone receptor trafficking at membrane microdomains. J Biol Chem 2011; 286:35020-9. [PMID: 21832055 PMCID: PMC3186428 DOI: 10.1074/jbc.m111.264978] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 08/05/2011] [Indexed: 12/21/2022] Open
Abstract
Na/H exchanger regulatory factor-1 (NHERF1) is a cytoplasmic PDZ (postsynaptic density 95/disc large/zona occludens) protein that assembles macromolecular complexes and determines the localization, trafficking, and signaling of select G protein-coupled receptors and other membrane-delimited proteins. The parathyroid hormone receptor (PTHR), which regulates mineral ion homeostasis and bone turnover, is a G protein-coupled receptor harboring a PDZ-binding motif that enables association with NHERF1 and tethering to the actin cytoskeleton. NHERF1 interactions with the PTHR modify its trafficking and signaling. Here, we characterized by live cell imaging the mechanism whereby NHERF1 coordinates the interactions of multiple proteins, as well as the fate of NHERF1 itself upon receptor activation. Upon PTHR stimulation, NHERF1 rapidly dissociates from the receptor and induces receptor aggregation in long lasting clusters that are enriched with the actin-binding protein ezrin and with clathrin. After NHERF1 dissociates from the PTHR, ezrin then directly interacts with the PTHR to stabilize the PTHR at the cell membrane. Recruitment of β-arrestins to the PTHR is delayed until NHERF1 dissociates from the receptor, which is then trafficked to clathrin for internalization. The ability of NHERF to interact dynamically with the PTHR and cognate adapter proteins regulates receptor trafficking and signaling in a spatially and temporally coordinated manner.
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Affiliation(s)
- Juan A. Ardura
- From the Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology and
| | - Bin Wang
- From the Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology and
| | - Simon C. Watkins
- the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Jean-Pierre Vilardaga
- From the Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology and
| | - Peter A. Friedman
- From the Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology and
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Cartier A, Parent A, Labrecque P, Laroche G, Parent JL. WDR36 acts as a scaffold protein tethering a G-protein-coupled receptor, Gαq and phospholipase Cβ in a signalling complex. J Cell Sci 2011; 124:3292-304. [DOI: 10.1242/jcs.085795] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We identified the WD-repeat-containing protein, WDR36, as an interacting partner of the β isoform of thromboxane A2 receptor (TPβ) by yeast two-hybrid screening. We demonstrated that WDR36 directly interacts with the C-terminus and the first intracellular loop of TPβ by in vitro GST-pulldown assays. The interaction in a cellular context was observed by co-immunoprecipitation, which was positively affected by TPβ stimulation. TPβ–WDR36 colocalization was detected by confocal microscopy at the plasma membrane in non-stimulated HEK293 cells but the complex translocated to intracellular vesicles following receptor stimulation. Coexpression of WDR36 and its siRNA-mediated knockdown, respectively, increased and inhibited TPβ-induced Gαq signalling. Interestingly, WDR36 co-immunoprecipitated with Gαq, and promoted TPβ–Gαq interaction. WDR36 also associated with phospholipase Cβ (PLCβ) and increased the interaction between Gαq and PLCβ, but prevented sequestration of activated Gαq by GRK2. In addition, the presence of TPβ in PLCβ immunoprecipitates was augmented by expression of WDR36. Finally, disease-associated variants of WDR36 affected its ability to modulate Gαq-mediated signalling by TPβ. We report that WDR36 acts as a new scaffold protein tethering a G-protein-coupled receptor, Gαq and PLCβ in a signalling complex.
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Affiliation(s)
- Andréane Cartier
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| | - Audrey Parent
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| | - Pascale Labrecque
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| | - Geneviève Laroche
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| | - Jean-Luc Parent
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
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41
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Ardura JA, Friedman PA. Regulation of G protein-coupled receptor function by Na+/H+ exchange regulatory factors. Pharmacol Rev 2011; 63:882-900. [PMID: 21873413 DOI: 10.1124/pr.110.004176] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Many G protein-coupled receptors (GPCR) exert patterns of cell-specific signaling and function. Mounting evidence now supports the view that cytoplasmic adapter proteins contribute critically to this behavior. Adapter proteins recognize highly conserved motifs such as those for Src homology 3 (SH3), phosphotyrosine-binding (PTB), and postsynaptic density 95/discs-large/zona occludens (PDZ) docking sequences in candidate GPCRs. Here we review the behavior of the Na+/H+ exchange regulatory factor (NHERF) family of PDZ adapter proteins on GPCR signalling, trafficking, and function. Structural determinants of NHERF proteins that allow them to recognize targeted GPCRs are considered. NHERF1 and NHERF2 are capable also of modifying the assembled complex of accessory proteins such as β-arrestins, which have been implicated in regulating GPCR signaling. In addition, NHERF1 and NHERF2 modulate GPCR signaling by altering the G protein to which the receptor binds or affect other regulatory proteins that affect GTPase activity, protein kinase A, phospholipase C, or modify downstream signaling events. Small molecules targeting the site of NHERF1-GPCR interaction are being developed and may become important and selective drug candidates.
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Affiliation(s)
- Juan A Ardura
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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42
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Stallaert W, Christopoulos A, Bouvier M. Ligand functional selectivity and quantitative pharmacology at G protein-coupled receptors. Expert Opin Drug Discov 2011; 6:811-25. [DOI: 10.1517/17460441.2011.586691] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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43
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Feinstein TN, Wehbi VL, Ardura JA, Wheeler DS, Ferrandon S, Gardella TJ, Vilardaga JP. Retromer terminates the generation of cAMP by internalized PTH receptors. Nat Chem Biol 2011; 7:278-84. [PMID: 21445058 PMCID: PMC3079799 DOI: 10.1038/nchembio.545] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 01/24/2011] [Indexed: 12/12/2022]
Abstract
The generation of cAMP by G protein-coupled receptors (GPCRs) and its termination are currently thought to occur exclusively at the plasma membrane of cells. Under existing models of receptor regulation, this signal is primarily restricted by desensitization of the receptors through their binding to β-arrestins. However, this paradigm is not consistent with recent observations that the parathyroid hormone receptor type 1 (PTHR) continues to stimulate cAMP production even after receptor internalization, as β-arrestins are known to rapidly bind and internalize activated PTHR. Here we show that binding to β-arrestin1 prolongs rather than terminates the generation of cAMP by PTHR, and that cAMP generation correlates with the persistence of arrestin-receptor complexes on endosomes. PTHR signaling is instead turned off by the retromer complex, which regulates the movement of internalized receptor from endosomes to the Golgi apparatus. Thus, binding by the retromer complex regulates the sustained generation of cAMP triggered by an internalized GPCR.
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Affiliation(s)
- Timothy N Feinstein
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
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44
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Alonso V, Ardura JA, Wang B, Sneddon WB, Friedman PA. A naturally occurring isoform inhibits parathyroid hormone receptor trafficking and signaling. J Bone Miner Res 2011; 26:143-55. [PMID: 20578167 PMCID: PMC3179322 DOI: 10.1002/jbmr.167] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Parathyroid hormone (PTH) regulates calcium homeostasis and bone remodeling through its cognitive receptor (PTHR). We describe here a PTHR isoform harboring an in-frame 42-bp deletion of exon 14 (Δe14-PTHR) that encodes transmembrane domain 7. Δe14-PTHR was detected in human kidney and buccal epithelial cells. We characterized its topology, cellular localization, and signaling, as well as its interactions with PTHR. The C-terminus of the Δe14-PTHR is extracellular, and cell surface expression is strikingly reduced compared with the PTHR. Δe14-PTHR displayed impaired trafficking and accumulated in endoplasmic reticulum. Signaling and activation of cAMP and ERK by Δe14-PTHR was decreased significantly compared with PTHR. Δe14-PTHR acts as a functional dominant-negative by suppressing the action of PTHR. Cells cotransfected with both receptors exhibit markedly reduced PTHR cell membrane expression, colocalization with Δe14-PTHR in endoplasmic reticulum, and diminished cAMP activation and ERK phosphorylation in response to challenge with PTH. Δe14-PTHR forms heterodimers with PTHR, which may account for cytoplasmic retention of PTHR in the presence of Δe14-PTHR. Analysis of the PTHR heteronuclear RNA suggests that base-pair complementarity in introns surrounding exon 14 causes exon skipping and accounts for generation of the Δe14-PTHR isoform. Thus Δe14-PTHR is a poorly functional receptor that acts as a dominant-negative of PTHR trafficking and signaling and may contribute to PTH resistance.
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Affiliation(s)
- Verónica Alonso
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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45
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Vilardaga JP, Romero G, Friedman PA, Gardella TJ. Molecular basis of parathyroid hormone receptor signaling and trafficking: a family B GPCR paradigm. Cell Mol Life Sci 2011; 68:1-13. [PMID: 20703892 PMCID: PMC3568769 DOI: 10.1007/s00018-010-0465-9] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/06/2010] [Accepted: 07/09/2010] [Indexed: 12/14/2022]
Abstract
The parathyroid hormone (PTH) receptor type 1 (PTHR), a G protein-coupled receptor (GPCR), transmits signals to two hormone systems-PTH, endocrine and homeostatic, and PTH-related peptide (PTHrP), paracrine-to regulate different biological processes. PTHR responds to these hormonal stimuli by activating heterotrimeric G proteins, such as G(S) that stimulates cAMP production. It was thought that the PTHR, as for all other GPCRs, is only active and signals through G proteins on the cell membrane, and internalizes into a cell to be desensitized and eventually degraded or recycled. Recent studies with cultured cell and animal models reveal a new pathway that involves sustained cAMP signaling from intracellular domains. Not only do these studies challenge the paradigm that cAMP production triggered by activated GPCRs originates exclusively at the cell membrane but they also advance a comprehensive model to account for the functional differences between PTH and PTHrP acting through the same receptor.
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Affiliation(s)
- Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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Proteins move! Protein dynamics and long-range allostery in cell signaling. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2011; 83:163-221. [PMID: 21570668 DOI: 10.1016/b978-0-12-381262-9.00005-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
An emerging point of view in protein chemistry is that proteins are not the static objects that are displayed in textbooks but are instead dynamic actors. Protein dynamics plays a fundamental role in many diseases, and spans a large hierarchy of timescales, from picoseconds to milliseconds or even longer. Nanoscale protein domain motion on length scales comparable to protein dimensions is key to understanding how signals are relayed through multiple protein-protein interactions. A canonical example is how the scaffolding proteins NHERF1 and ezrin work in coordination to assemble crucial membrane complexes. As membrane-cytoskeleton scaffolding proteins, these provide excellent prototypes for understanding how regulatory signals are relayed through protein-protein interactions between the membrane and the cytoskeleton. Here, we review recent progress in understanding the structure and dynamics of the interaction. We describe recent novel applications of neutron spin echo spectroscopy to reveal the dynamic propagation of allosteric signals by nanoscale protein motion, and present a guide to the future study of dynamics and its application to the cure of disease.
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Romero G, von Zastrow M, Friedman PA. Role of PDZ proteins in regulating trafficking, signaling, and function of GPCRs: means, motif, and opportunity. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2011; 62:279-314. [PMID: 21907913 DOI: 10.1016/b978-0-12-385952-5.00003-8] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PDZ proteins, named for the common structural domain shared by the postsynaptic density protein (PSD95), Drosophila disc large tumor suppressor (DlgA), and zonula occludens-1 protein (ZO-1), constitute a family of 200-300 recognized members. These cytoplasmic adapter proteins are capable of assembling a variety of membrane-associated proteins and signaling molecules in short-lived functional units. Here, we review PDZ proteins that participate in the regulation of signaling, trafficking, and function of G protein-coupled receptors. Salient structural features of PDZ proteins that allow them to recognize targeted GPCRs are considered. Scaffolding proteins harboring PDZ domains may contain single or multiple PDZ modules and may also include other protein-protein interaction modules. PDZ proteins may impact receptor signaling by diverse mechanisms that include retaining the receptor at the cell membrane, thereby increasing the duration of ligand binding, as well as importantly influencing GPCR internalization, trafficking, recycling, and intracellular sorting. PDZ proteins are also capable of modifying the assembled complex of accessory proteins such as β-arrestins that themselves regulate GPCR signaling. Additionally, PDZ proteins may modulate GPCR signaling by altering the G protein to which the receptor binds, or affect other regulatory proteins that impact GTPase activity, protein kinase A, phospholipase C, or modify downstream signaling events. Small molecules targeting the PDZ protein-GPCR interaction are being developed and may become important and selective drug candidates.
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Affiliation(s)
- Guillermo Romero
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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48
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Hammad MM, Kuang YQ, Yan R, Allen H, Dupré DJ. Na+/H+ exchanger regulatory factor-1 is involved in chemokine receptor homodimer CCR5 internalization and signal transduction but does not affect CXCR4 homodimer or CXCR4-CCR5 heterodimer. J Biol Chem 2010; 285:34653-64. [PMID: 20801883 PMCID: PMC2966081 DOI: 10.1074/jbc.m110.106591] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 08/25/2010] [Indexed: 11/06/2022] Open
Abstract
Chemokine receptors are members of the G protein-coupled receptor (GPCR) family. CCR5 is also the principal co-receptor for macrophage-tropic strains of human immunodeficiency virus, type 1 (HIV-1), and efforts have been made to develop ligands to inhibit HIV-1 infection by promoting CCR5 receptor endocytosis. Given the nature of GPCRs and their propensity to form oligomers, one can consider ligand-based therapies as unselective in terms of the oligomeric composition of complexes. For example, a ligand targeting a CCR5 homomer could likely induce signal transduction on a heteromeric CCR5-CXCR4. Other avenues could therefore be explored. We identified a receptor adaptor interacting specifically with one receptor complex but not others. NHERF1, an adaptor known for its role in desensitization, internalization, and regulation of the ERK signaling cascade for several GPCRs, interacts via its PDZ2 domain with the CCR5 homodimer but not with the CXCR4-CCR5 heterodimer or CXCR4 homodimer. To further characterize this interaction, we also show that NHERF1 increases the CCR5 recruitment of arrestin2 following stimulation. NHERF1 is also involved in CCR5 internalization, as we demonstrate that co-expression of constructs bearing the PDZ2 domain can block CCR5 internalization. We also show that NHERF1 potentiates RANTES (regulated on activation normal T cell expressed and secreted)-induced ERK1/2 phosphorylation via CCR5 activation and that this activation requires NHERF1 but not arrestin2. Taken together, our results suggest that oligomeric receptor complexes can associate specifically with partners and that in this case NHERF1 could represent an interesting new target for the regulation of CCR5 internalization and potentially HIV infection.
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Affiliation(s)
- Maha M. Hammad
- From the Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | - Yi-Qun Kuang
- From the Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | - Ronald Yan
- From the Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | - Heather Allen
- From the Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | - Denis J. Dupré
- From the Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
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Yanamala N, Klein-Seetharaman J. Allosteric Modulation of G Protein Coupled Receptors by Cytoplasmic, Transmembrane and Extracellular Ligands. Pharmaceuticals (Basel) 2010; 3:3324-3342. [PMID: 24009470 PMCID: PMC3760430 DOI: 10.3390/ph3103324] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
G protein coupled receptors (GPCRs) bind diverse classes of ligands, and depending on the receptor, these may bind in their transmembrane or the extracellular domains, demonstrating the principal ability of GPCRs to bind ligand in either domains. Most recently, it was also observed that small molecule ligands can bind in the cytoplasmic domain, and modulate binding and response to extracellular or transmembrane ligands. Thus, all three domains in GPCRs are potential sites for allosteric ligands, and whether a ligand is allosteric or orthosteric depends on the receptor. Here, we will review the evidence supporting the presence of putative binding pockets in all three domains of GPCRs and discuss possible pathways of communication between these pockets.
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Affiliation(s)
| | - Judith Klein-Seetharaman
- To whom correspondence should be addressed; E-Mail: ; Tel.: +1 412 383 7325; Fax: +1 412 648 8998
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EBP50 inhibits the anti-mitogenic action of the parathyroid hormone type 1 receptor in vascular smooth muscle cells. J Mol Cell Cardiol 2010; 49:1012-21. [PMID: 20843475 DOI: 10.1016/j.yjmcc.2010.08.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 08/11/2010] [Accepted: 08/29/2010] [Indexed: 11/23/2022]
Abstract
Parathyroid hormone-related protein (PTHrP) and the parathyroid hormone type 1 receptor (PTH1R) are important regulators of vascular remodeling. PTHrP expression is associated to increased proliferation of vascular smooth muscle cells (VSMC). In contrast, signaling via the PTH1R inhibits cell growth. The mechanisms regulating the dual effect of PTHrP and PTH1R on VSMC proliferation are only partially understood. In this study we examined the role of the adaptor protein ezrin-radixin-moesin-binding phosphoprotein (EBP50) on PTH1R expression, trafficking, signaling and control of A10 cell proliferation. In normal rat vascular tissues, EBP50 was restricted to the endothelium with little expression in VSMC. EBP50 expression significantly increased in VSMC following angioplasty in parallel with PTHrP. Interestingly, PTHrP was able to induce EBP50 expression. In the clonal rat aortic smooth muscle cell line A10, EBP50 increased the recruitment of PTH1R to the cell membrane and delayed its internalization in response to PTHrP(1-36). This effect required an intact C-terminal motif in the PTH1R. In naïve A10 cells, PTHrP(1-36) stimulated cAMP production but not intracellular calcium release. In contrast, PTHrP(1-36) induced both cAMP and calcium signaling in A10 cells over-expressing EBP50. Finally, EBP50 attenuated the induction of p27(kip1) and the anti-proliferative effect of PTHrP(1-36). In summary, this study demonstrates the dynamic expression of EBP50 in vessels following injury and the effects of EBP50 on PTH1R function in VSMC. These findings highlight one of the mechanisms leading to increased VSMC proliferation and have important implication in the understanding of the molecular events leading to restenosis.
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