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Chang L, Chen Q, Wang B, Liu J, Zhang M, Zhu W, Jiang J. Single cell RNA analysis uncovers the cell differentiation and functionalization for air breathing of frog lung. Commun Biol 2024; 7:665. [PMID: 38816547 PMCID: PMC11139932 DOI: 10.1038/s42003-024-06369-1] [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: 10/11/2023] [Accepted: 05/21/2024] [Indexed: 06/01/2024] Open
Abstract
The evolution and development of vertebrate lungs have been widely studied due to their significance in terrestrial adaptation. Amphibians possess the most primitive lungs among tetrapods, underscoring their evolutionary importance in bridging the transition from aquatic to terrestrial life. However, the intricate process of cell differentiation during amphibian lung development remains poorly understood. Using single-cell RNA sequencing, we identify 13 cell types in the developing lungs of a land-dwelling frog (Microhyla fissipes). We elucidate the differentiation trajectories and mechanisms of mesenchymal cells, identifying five cell fates and their respective driver genes. Using temporal dynamics analyses, we reveal the gene expression switches of epithelial cells, which facilitate air breathing during metamorphosis. Furthermore, by integrating the published data from another amphibian and two terrestrial mammals, we illuminate both conserved and divergent cellular repertoires during the evolution of tetrapod lungs. These findings uncover the frog lung cell differentiation trajectories and functionalization for breathing in air and provide valuable insights into the cell-type evolution of vertebrate lungs.
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Affiliation(s)
- Liming Chang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiheng Chen
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Bin Wang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
| | - Jiongyu Liu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
| | - Meihua Zhang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
| | - Wei Zhu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Jianping Jiang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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Wang X, Wu P, Fu Y, Yang R, Li C, Chen Y, He A, Chen X, Ma D, Ma J, Zhang T. The circular RNA expression profile of human auricle cartilage and the role of circCOL1A2 in isolated microtia. Cell Signal 2024; 115:111017. [PMID: 38123043 DOI: 10.1016/j.cellsig.2023.111017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 11/24/2023] [Accepted: 12/15/2023] [Indexed: 12/23/2023]
Abstract
Microtia is one of the most common craniofacial birth defects worldwide, and its primary clinical manifestation is auricle deformity. Epigenetic factors are known to contribute to the etiology of microtia, yet the involvement of circular RNAs (circRNAs) in human auricle development and their association with microtia remains poorly understood. In this study, we aimed to analyze differentially expressed circRNAs and explore their functional implications in isolated microtia. By employing circRNA microarray analysis and bioinformatics approaches, we identified 340 differentially expressed circRNAs in auricle cartilage of patients with isolated microtia, comprising 152 upregulated and 188 downregulated circRNAs. A circRNA-mRNA co-expression network was constructed, followed by gene ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Subsequently, we selected four significantly upregulated circRNAs from the co-expression network based on their association with cartilage development and validated their expressions in 30 isolated microtia and 30 control clinical auricle cartilage samples. Among these circRNAs, circCOL1A2, the most significantly upregulated circRNA, was selected as a representative circRNA for investigating its role in isolated microtia. Overexpression of circCOL1A2 significantly inhibited chondrocyte proliferation and chondrogenic differentiation of human mesenchymal stem cells. Additionally, circCOL1A2 upregulated Dermatan Sulfate Epimerase Like (DSEL) expression by sponging miR-637 through the competing endogenous RNA (ceRNA) mechanism. Notably, the downregulation of DSEL attenuated the inhibitory effect of circCOL1A2 overexpression on cell proliferation and chondrogenic differentiation. Collectively, these findings highlight the involvement of circCOL1A2 in the pathogenesis of isolated microtia and emphasize the potential significance of dysregulated circRNAs in disease development.
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Affiliation(s)
- Xin Wang
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China
| | - Peixuan Wu
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
| | - Yaoyao Fu
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China
| | - Run Yang
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China.
| | - Chenlong Li
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China
| | - Ying Chen
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China
| | - Aijuan He
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China
| | - Xin Chen
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China.
| | - Duan Ma
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
| | - Jing Ma
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China.
| | - Tianyu Zhang
- ENT Institute, Department of Facial Plastic and Reconstructive Surgery, Eye & ENT Hospital, Fudan University, Shanghai 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai 200031, China.
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3
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Liu H, Liu L, Rosen CJ. PTH and the Regulation of Mesenchymal Cells within the Bone Marrow Niche. Cells 2024; 13:406. [PMID: 38474370 PMCID: PMC10930661 DOI: 10.3390/cells13050406] [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: 12/05/2023] [Revised: 02/05/2024] [Accepted: 02/20/2024] [Indexed: 03/14/2024] Open
Abstract
Parathyroid hormone (PTH) plays a pivotal role in maintaining calcium homeostasis, largely by modulating bone remodeling processes. Its effects on bone are notably dependent on the duration and frequency of exposure. Specifically, PTH can initiate both bone formation and resorption, with the outcome being influenced by the manner of PTH administration: continuous or intermittent. In continuous administration, PTH tends to promote bone resorption, possibly by regulating certain genes within bone cells. Conversely, intermittent exposure generally favors bone formation, possibly through transient gene activation. PTH's role extends to various aspects of bone cell activity. It directly influences skeletal stem cells, osteoblastic lineage cells, osteocytes, and T cells, playing a critical role in bone generation. Simultaneously, it indirectly affects osteoclast precursor cells and osteoclasts, and has a direct impact on T cells, contributing to its role in bone resorption. Despite these insights, the intricate mechanisms through which PTH acts within the bone marrow niche are not entirely understood. This article reviews the dual roles of PTH-catabolic and anabolic-on bone cells, highlighting the cellular and molecular pathways involved in these processes. The complex interplay of these factors in bone remodeling underscores the need for further investigation to fully comprehend PTH's multifaceted influence on bone health.
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Affiliation(s)
- Hanghang Liu
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China;
- Maine Medical Center, MaineHealth Institute for Research, 81 Research Drive, Scarborough, ME 04074, USA;
| | - Linyi Liu
- Maine Medical Center, MaineHealth Institute for Research, 81 Research Drive, Scarborough, ME 04074, USA;
| | - Clifford J. Rosen
- Maine Medical Center, MaineHealth Institute for Research, 81 Research Drive, Scarborough, ME 04074, USA;
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Portales-Castillo I, Dean T, Cheloha RW, Creemer BA, Vilardaga JP, Savransky S, Khatri A, Jüppner H, Gardella TJ. Altered Signaling and Desensitization Responses in PTH1R Mutants Associated with Eiken Syndrome. Commun Biol 2023; 6:599. [PMID: 37268817 PMCID: PMC10238420 DOI: 10.1038/s42003-023-04966-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 05/22/2023] [Indexed: 06/04/2023] Open
Abstract
The parathyroid hormone receptor type 1 (PTH1R) is a G protein-coupled receptor that plays key roles in regulating calcium homeostasis and skeletal development via binding the ligands, PTH and PTH-related protein (PTHrP), respectively. Eiken syndrome is a rare disease of delayed bone mineralization caused by homozygous PTH1R mutations. Of the three mutations identified so far, R485X, truncates the PTH1R C-terminal tail, while E35K and Y134S alter residues in the receptor's amino-terminal extracellular domain. Here, using a variety of cell-based assays, we show that R485X increases the receptor's basal rate of cAMP signaling and decreases its capacity to recruit β-arrestin2 upon ligand stimulation. The E35K and Y134S mutations each weaken the binding of PTHrP leading to impaired β-arrestin2 recruitment and desensitization of cAMP signaling response to PTHrP but not PTH. Our findings support a critical role for interaction with β-arrestin in the mechanism by which the PTH1R regulates bone formation.
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Affiliation(s)
- Ignacio Portales-Castillo
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Thier Research Building, 50 Blossom St, Boston, MA, 02114, USA
- Department of Medicine, Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Thier Research Building, 50 Blossom St, Boston, MA, 02114, USA
- Department of Medicine, Division of Nephrology, Washington University in St. Louis, BJCIH Building, 425 South Euclid St, St. Louis, MO, 63110, USA
| | - Thomas Dean
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Thier Research Building, 50 Blossom St, Boston, MA, 02114, USA
| | - Ross W Cheloha
- Chemical Biology in Signaling Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, Building 8, 8 Center Drive, Bethesda, MD, 20891, USA
| | - Brendan A Creemer
- Chemical Biology in Signaling Section, Laboratory of Bioorganic Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, Building 8, 8 Center Drive, Bethesda, MD, 20891, USA
| | - Jean-Pierre Vilardaga
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Thomas E. Starzl Biomedical Science Tower, 200 Lothrop St, Pittsburgh, PA, 15261, USA
| | - Sofya Savransky
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Thomas E. Starzl Biomedical Science Tower, 200 Lothrop St, Pittsburgh, PA, 15261, USA
| | - Ashok Khatri
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Thier Research Building, 50 Blossom St, Boston, MA, 02114, USA
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Thier Research Building, 50 Blossom St, Boston, MA, 02114, USA
- Pediatric Nephrology Unit, Massachusetts General Hospital, and Harvard Medical School, Thier Research Building, 50 Blossom St, Boston, MA, 02114, USA
| | - Thomas J Gardella
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Thier Research Building, 50 Blossom St, Boston, MA, 02114, USA.
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Inactivation of Osteoblast PKC Signaling Reduces Cortical Bone Mass and Density and Aggravates Renal Osteodystrophy in Mice with Chronic Kidney Disease on High Phosphate Diet. Int J Mol Sci 2022; 23:ijms23126404. [PMID: 35742850 PMCID: PMC9223847 DOI: 10.3390/ijms23126404] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/01/2022] [Accepted: 06/06/2022] [Indexed: 02/05/2023] Open
Abstract
Chronic kidney disease (CKD) frequently leads to hyperphosphatemia and hyperparathyroidism, mineral bone disorder (CKD-MBD), ectopic calcifications and cardiovascular mortality. PTH activates the osteoanabolic Gαs/PKA and the Gαq/11/PKC pathways in osteoblasts, the specific impact of the latter in CKD-MBD is unknown. We generated osteoblast specific Gαq/11 knockout (KO) mice and established CKD-MBD by subtotal nephrectomy and dietary phosphate load. Bone morphology was assessed by micro-CT, osteoblast function by bone planar scintigraphy at week 10 and 22 and by histomorphometry. Osteoblasts isolated from Gαq/11 KO mice increased cAMP but not IP3 in response to PTH 1-34, demonstrating the specific KO of the PKC signaling pathway. Osteoblast specific Gαq/11 KO mice exhibited increased serum calcium and reduced bone cortical thickness and mineral density at 24 weeks. CKD Gαq/11 KO mice had similar bone morphology compared to WT, while CKD Gαq/11-KO on high phosphate diet developed decreased metaphyseal and diaphyseal cortical thickness and area, as well as a reduction in trabecular number. Gαq/11-KO increased bone scintigraphic tracer uptake at week 10 and mitigated tracer uptake in CKD mice at week 22. Histological bone parameters indicated similar trends. Gαq/11-KO in osteoblast modulates calcium homeostasis, bone formation rate, bone morphometry, and bone mineral density. In CKD and high dietary phosphate intake, osteoblast Gαq/11/PKC KO further aggravates mineral bone disease.
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Portales‐Castillo I, Dean T, Khatri A, Jüppner H, Gardella TJ. Functional Properties of Two Distinct PTH1R Mutants Associated With Either Skeletal Defects or Pseudohypoparathyroidism. JBMR Plus 2022; 6:e10604. [PMID: 35720667 PMCID: PMC9189904 DOI: 10.1002/jbm4.10604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/11/2022] [Indexed: 12/03/2022] Open
Abstract
Consistent with a vital role of parathyroid hormone (PTH) receptor type 1 (PTH1R) in skeletal development, homozygous loss-of-function PTH1R mutations in humans results in neonatal lethality (Blomstrand chondrodysplasia), whereas such heterozygous mutations cause a primary failure of tooth eruption (PFE). Despite a key role of PTH1R in calcium and phosphate homeostasis, blood mineral ion levels are not altered in such cases of PFE. Recently, two nonlethal homozygous PTH1R mutations were identified in two unrelated families in which affected members exhibit either dental and skeletal abnormalities (PTH1R-V204E) or hypocalcemia and hyperphosphatemia (PTH1R-R186H). Arg186 and Val204 map to the first transmembrane helix of the PTH1R, and thus to a critical region of this class B G protein-coupled receptor. We used cell-based assays and PTH and PTH-related protein (PTHrP) ligand analogs to assess the impact of the R186H and V204E mutations on PTH1R function in vitro. In transiently transfected HEK293 cells, PTH1R-R186H mediated cyclic adenosine monophosphate (cAMP) responses to PTH(1-34) and PTHrP(1-36) that were of comparable potency to those observed on wild-type PTH1R (PTH1R-WT) (half maximal effective concentrations [EC50s] = 0.4nM to 1.2nM), whereas the response-maxima were significantly reduced for the PTH1R-V204E mutant (maximum effect [Emax] = 81%-77% of PTH1R-WT, p ≤ 0.004). Antibody binding to an extracellular hemagglutinin (HA) tag was comparable for PTH1R-R186H and PTH1R-WT, but was significantly reduced for PTH1R-V204E (maximum binding level [Bmax] = 44% ± 11% of PTH1R-WT, p = 0.002). The potency of cAMP signaling induced by a PTH(1-11) analog was reduced by ninefold and threefold, respectively, for PTH1R-R186H and PTH1R-V204E, relative to PTH1R-WT, and a PTH(1-15) radioligand analog that bound adequately to PTH1R-WT exhibited little or no specific binding to either mutant receptor. The data support a general decrease in PTH1R surface expression and/or function as a mechanism for PFE and a selective impairment in PTH ligand affinity as a potential PTH1R-mutation-based mechanism for pseudohypoparathyroidism. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Ignacio Portales‐Castillo
- Department of Medicine, Division of NephrologyMassachusetts General Hospital, and Harvard Medical SchoolBostonMAUSA
| | - Thomas Dean
- Endocrine UnitMassachusetts General Hospital, and Harvard Medical SchoolBostonMAUSA
| | - Ashok Khatri
- Endocrine UnitMassachusetts General Hospital, and Harvard Medical SchoolBostonMAUSA
| | - Harald Jüppner
- Endocrine UnitMassachusetts General Hospital, and Harvard Medical SchoolBostonMAUSA
- Pediatric Nephrology UnitMassachusetts General Hospital, and Harvard Medical SchoolBostonMAUSA
| | - Thomas J Gardella
- Endocrine UnitMassachusetts General Hospital, and Harvard Medical SchoolBostonMAUSA
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Parathyroid hormone (PTH) regulation of metabolic homeostasis: An old dog teaches us new tricks. Mol Metab 2022; 60:101480. [PMID: 35338013 PMCID: PMC8980887 DOI: 10.1016/j.molmet.2022.101480] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/11/2022] [Accepted: 03/16/2022] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Late in the nineteenth century, it was theorized that a circulating product produced by the parathyroid glands could negatively impact skeletal homeostasis. A century later, intermittent administration of that protein, namely parathyroid hormone (PTH), was approved by the FDA and EMA as the first anabolic agent to treat osteoporosis. Yet, several unanswered but important questions remain about the skeletal actions of PTH. SCOPE OF REVIEW Current research efforts have focused on improving the efficacy of PTH treatment by designing structural analogs and identifying other targets (e.g., the PTH or the calcium sensing receptor). A unique but only recently described aspect of PTH action is its regulation of cellular bioenergetics and metabolism, namely in bone and adipose tissue but also in other tissues. The current review aims to provide a brief background on PTH's previously described actions on bone and highlights how PTH regulates osteoblast bioenergetics, contributing to greater bone formation. It will also shed light on how PTH could alter metabolic homeostasis through its actions in other cells and tissues, thereby impacting the skeleton in a cell non-autonomous manner. MAJOR CONCLUSIONS PTH administration enhances bone formation by targeting the osteoblast through transcriptional changes in several pathways; the most prominent is via adenyl cyclase and PKA. PTH and its related protein, PTHrP, also induce glycolysis and fatty acid oxidation in bone cells and drive lipolysis and thermogenic programming in adipocytes; the latter may indirectly but positively influence skeletal metabolism. While much work remains, alterations in cellular metabolism may also provide a novel mechanism related to PTH's temporal actions. Thus, the bioenergetic impact of PTH can be considered another of the myriad anabolic effects of PTH on the skeleton. Just as importantly from a translational perspective, the non-skeletal metabolic effects may lead to a better understanding of whole-body homeostasis along with new and improved therapies to treat musculoskeletal conditions.
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Song MS, Yu X, Rong PZ, Pang QJ. The Effects of Signaling-Selective Parathyroid Hormone Analogs on Osteoporotic Osteocyte Apoptosis. J BIOMATER TISS ENG 2022. [DOI: 10.1166/jbt.2022.2904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Objectives: To compare the effects of signaling-selective parathyroid hormone analogs [G1, R19]hPTH(1–28) [GR(1–28)] and [G1, R19]hPTH(1–34) [GR(1–34)] on osteoporotic osteocyte apoptosis, and to explore the mechanism of the anti-osteoporotic difference.
Methods: The osteoporosis model was established in eighty adult female C57BL/6 mice aged 12 weeks. The mice were subcutaneously administered with GR(1–28) and GR(1–34) 5 days per week for 8 weeks. Bilateral femur samples were collected at 4 and 8 weeks, and micro-computed
tomography (CT), H&E staining and immunohistochemical staining analyses were performed. Results: From micro-CT analysis, GR(1–34) increased proximal femoral bone mineral density (BMD) and relative bone volume (BV/TV), which was higher than GR(1–28) did. In addition,
more trabecular number (Tb.N), thinner trabecular thickness (Tb.Th) and wider trabecular separation (Tb.Sp) were measured at week 8 using GR(1–34). From H&E and immunohistochemical staining, a stronger apoptosis inhibition was induced by GR(1–34) with more Bcl-2 secretion
but less Bax expression, as opposed to GR(1–28). Conclusions: GR(1–34) shows better anti-osteoporotic effects than GR(1–28), which appears to be attributed to the activation of the PLC-independent PKC signaling pathway triggered by the former, inhibiting osteocyte
apoptosis through up-regulation of Bcl-2 and down-regulation of Bax to increase bone mass and improving trabecular bone microstructure to enhance bone quality by reducing trabecular number, increasing trabecular thickness and trabecular space.
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Affiliation(s)
- Meng-Sheng Song
- Department of Orthopedics, HwaMei Hospital, University of Chinese Academy of Sciences; Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo 315000, Zhejiang, China
| | - Xiao Yu
- Department of Orthopedics, HwaMei Hospital, University of Chinese Academy of Sciences; Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo 315000, Zhejiang, China
| | - Peng-Ze Rong
- Ningbo University School of Medicine, Ningbo 315211, China
| | - Qing-Jiang Pang
- Department of Orthopedics, HwaMei Hospital, University of Chinese Academy of Sciences; Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo 315000, Zhejiang, China
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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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He Y, Li M, Tong G, Meng Y, Hao S, Hu S, Yan W, Yang D. hPTH(3-34)(29-34) selectively activated PKC and mimicked osteoanabolic effects of hPTH(1-34). Bone 2020; 135:115326. [PMID: 32200023 DOI: 10.1016/j.bone.2020.115326] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/15/2020] [Accepted: 03/17/2020] [Indexed: 01/07/2023]
Abstract
Teriparatide (hPTH(1-34)) exhibits both osteoanabolic and osteocatabolic effects. We generated a novel PTH analog by duplicating the PTH(29-34) domain to hPTH(3-34) (named MY-1), which was identified to activate PKC but not PLC and cAMP/PKA signaling. It increased osteo-differentiation but did not affect osteoclastogenesis and RANKL expression in primary osteoblasts or bone marrow cells. MY-1 and hPTH(1-34) increased the synthesis and decreased the degradation οf β-catenin protein in osteoblasts, while PKC inhibitor blunted such effects. In vivo results indicated that intermittent MY-1 and hPTH(1-34) prevented bone loss in ovariectomized mice, and that MY-1 infusion increased bone volume in normal mice. Histological analysis observed more osteoclasts surrounding the cancellous bone surface in hPTH(1-34), but not MY-1 treated mice. We conclude that MY-1 mimicked the osteoanabolic but not the osteocatabolic effects of hPTH(1-34), which is related to PKC and β-catenin signaling. Such anabolic-only analog provides a new strategy to study PTH's versatile functions and design new medicines to treat osteoporosis and bone defects.
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Affiliation(s)
- Youhua He
- Department of Orthopedics-Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Minghan Li
- Department of Orthopedics-Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Guojun Tong
- Department of Orthopedics-Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Yue Meng
- Department of Orthopedics-Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Song Hao
- Department of Orthopedics-Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Shaoyu Hu
- Department of Orthopedics-Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Wenjuan Yan
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
| | - Dehong Yang
- Department of Orthopedics-Spine Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
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Zhang Y, Luo G, Yu X. Cellular Communication in Bone Homeostasis and the Related Anti-osteoporotic Drug Development. Curr Med Chem 2020; 27:1151-1169. [PMID: 30068268 DOI: 10.2174/0929867325666180801145614] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/28/2018] [Accepted: 07/19/2018] [Indexed: 02/08/2023]
Abstract
Background:Intercellular crosstalk among osteoblast, osteoclast, osteocyte and chondrocyte is involved in the precise control of bone homeostasis. Disruption of this cellular and molecular signaling would lead to metabolic bone diseases such as osteoporosis. Currently a number of anti-osteoporosis interventions are restricted by side effects, complications and long-term intolerance. This review aims to summarize the bone cellular communication involved in bone remodeling and its usage to develop new drugs for osteoporosis. Methods:We searched PubMed for publications from 1 January 1980 to 1 January 2018 to identify relevant and latest literatures, evaluation and prospect of osteoporosis medication were summarized. Detailed search terms were 'osteoporosis', 'osteocyte', 'osteoblast', 'osteoclast', 'bone remodeling', 'chondrocyte', 'osteoporosis treatment', 'osteoporosis therapy', 'bisphosphonates', 'denosumab', 'Selective Estrogen Receptor Modulator (SERM)', 'PTH', 'romosozumab', 'dkk-1 antagonist', 'strontium ranelate'. Results:A total of 170 papers were included in the review. About 80 papers described bone cell interactions involved in bone remodeling. The remaining papers were focused on the novel advanced and new horizons in osteoporosis therapies. Conclusion:There exists a complex signal network among bone cells involved in bone remodeling. The disorder of cell-cell communications may be the underlying mechanism of osteoporosis. Current anti-osteoporosis therapies are effective but accompanied by certain drawbacks simultaneously. Restoring the abnormal signal network and individualized therapy are critical for ideal drug development.
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Affiliation(s)
- Yi Zhang
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology and Metabolism, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Guojing Luo
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology and Metabolism, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Xijie Yu
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology and Metabolism, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
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12
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Feehan J, Al Saedi A, Duque G. Targeting fundamental aging mechanisms to treat osteoporosis. Expert Opin Ther Targets 2019; 23:1031-1039. [PMID: 31815563 DOI: 10.1080/14728222.2019.1702973] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Introduction: Osteoporotic fractures represent a growing burden of mortality, morbidity and socioeconomic cost to health-care systems worldwide. Osteoporosis is a disease uniquely associated with aging, therefore, an understanding of the physiological mechanisms underpinning its development as we age may open new avenues for therapeutic exploitation. Novel treatments, as well as refinement of the current approaches, are vital in the effort to sustain healthy, independent patients across the lifespan.Areas covered: This review covers the anabolic and catabolic pathways seen in bone maintenance, highlighting how they are changed with age, leading to osteoporosis. It will also discuss how these changes may be targeted therapeutically, in the development of new therapies, and the refinement of those already in use.Expert opinion: New effective and safe treatments for osteoporosis are still needed. Bone anabolics seem to be the most appropriate therapeutic approach to osteoporosis in older persons. Considering that bone and muscle mass synchronically decline with aging thus predisposing older persons to falls and fractures, combined therapeutic approaches to osteosarcopenia with a dual anabolic effect on muscle and bone will be a major advance in the treatment of these devastating conditions in the future.
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Affiliation(s)
- Jack Feehan
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, Australia.,Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, Australia
| | - Ahmed Al Saedi
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, Australia.,Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, Australia
| | - Gustavo Duque
- Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St. Albans, Australia.,Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St. Albans, Australia
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13
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Pozo A, Regnier M, Lizotte J, Martineau C, Scorza T, Moreau R. Cyclic adenosine monophosphate-dependent activation of transient receptor potential vanilloid 4 (TRPV4) channels in osteoblast-like MG-63 cells. Cell Signal 2019; 66:109486. [PMID: 31778738 DOI: 10.1016/j.cellsig.2019.109486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 11/23/2019] [Accepted: 11/24/2019] [Indexed: 10/25/2022]
Abstract
Parathyroid hormone (PTH) directly interacts with bone remodeling osteoblasts and osteocytes expressing the G-protein coupled receptor PTH receptor 1 (PTH1R), and its osteoanabolic effects mostly involve the cAMP/PKA signaling cascade. Considering that PTH-dependent calcium entry in rat enterocytes is reproduced by the adenylate cyclase agonist forskolin or by cAMP analogues, possible involvement of calcium as a second messenger in PTH-dependent cAMP signaling was investigated in MG-63 cells. First, Ca2+ influx was confirmed in Fluo3-loaded MG-63 cells treated with a cell-permeable cAMP analog. Second, PTH (1-34) and forskolin promoted calcium influxes that were completely abrogated by the PKA inhibitor H-89. Ca2+ entry was not reproduced when PTH (1-34) was combined with the PKC-activating competitor PTH (3-34). Vanilloid transient potential (TRPV) channel inhibitor Ruthenium Red, but not a voltage-dependent calcium channel (VDCC) inhibitor nifedipine, efficiently stunted Ca2+ entry, and comparable abrogation was reproduced in cells treated with TRPV4-selective inhibitor RN-1734 or transfected with TRPV4-specific siRNA. Interestingly, PTH-driven Ca2+ through TRPV4 significantly inhibited MG63 cell migration through a mechanism requiring extracellular Ca2+. In contrast, the inhibitory effects of forskolin on migration were refractory to TRPV4 silencing or to RN-1734. Altogether, our results indicate that single treatment with PTH (1-34) promotes extracellular calcium entry through TRPV4 channels in MG-63 cells through a cAMP/PKA-dependent mechanism, and that this influx affects cell migration.
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Affiliation(s)
- Arleth Pozo
- Département des sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Marine Regnier
- Département des sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Jérôme Lizotte
- Département des sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Corine Martineau
- Département des sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Tatiana Scorza
- Département des sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada.
| | - Robert Moreau
- Département des sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
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14
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Zhao P, Furness SGB. The nature of efficacy at G protein-coupled receptors. Biochem Pharmacol 2019; 170:113647. [PMID: 31585071 DOI: 10.1016/j.bcp.2019.113647] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 09/27/2019] [Indexed: 12/31/2022]
Abstract
G protein-coupled receptors (GPCRs) participate in many pathophysiological processes as well as almost all aspects of normal physiology. They are present at the surface of all cell types making them amenable and attractive targets for pharmaceutical therapeutics. GPCRs possess complex pharmacology with the ability to be turned on to various extents, have their constitutive activity suppressed and even switch between signaling pathways to which they couple. Underlying this complex pharmacology is GPCR signaling efficacy, and differences in efficacy promoted by alternative ligands and in different tissues is of great interest to biology in general and also the pharmaceutical industry. In this review we hope to discuss what the molecular foundations of efficacy are and whether a new approach utilizing a rate-dependent model may provide new insights into this phenomenon.
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Affiliation(s)
- Peishen Zhao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia.
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia.
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15
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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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16
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Li W, Yuan L, Tong G, He Y, Meng Y, Hao S, Chen J, Guo J, Bringhurst R, Yang D. Phospholipase C signaling activated by parathyroid hormone mediates the rapid osteoclastogenesis in the fracture healing of orchiectomized mice. BMC Musculoskelet Disord 2018; 19:311. [PMID: 30157832 PMCID: PMC6116492 DOI: 10.1186/s12891-018-2231-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 08/14/2018] [Indexed: 12/31/2022] Open
Abstract
Background The age-related osteoporosis is an increasing risk severely threatening the live quality of aged people. Human parathyroid hormone (hPTH) is applied to the therapy of osteoporosis successfully, however, the mechanism, especially the signaling pathway activated in the healing fracture by PTH is still unknown. Methods The once daily injections of hPTH(1–34) and GR (1–34) (the PLC deficient analog) into the orchiectomized male mice with bone fracture, were started at the second day after fracture and lasted for 4 weeks. To explore the role of phospholipase C signaling in the androgen-deficient fracture healing, the fracture healing were evaluated via radiography, micro-CT, biomechanics testing, serum biochemistry, bone marrow cell culture and gene expression quantification. Results After two weeks of fracture, both peptides significantly increased bone mineral density (BMD), bone mass content (BMC) and bone volume (BV/TV) in the healing area. However, compared to hPTH(1–34), GR(1–34) induced more woven bones, the higher BMC and BMD, as well as the less serum TRAP and osteoclasts. After four weeks of treatment, the effects of hPTH(1–34) on fracture healing showed no difference to those of GR(1–34). Consistently, GR(1–34) induced the similar osteogenesis but less osteoclastogenesis under the ex vivo condition immediately after administration compared to hPTH(1–34), which was verified by the weaker activation of RANKL, NFATC1, TRAP and Cathepsin K in GR(1–34) treatment. Conclusion These results indicated that the PLC signaling activated by the intermittent injection of hPTH(1–34) leads to the bone resorption by rapidly activating the osteoclastogenesis in the fracture healing zone. Electronic supplementary material The online version of this article (10.1186/s12891-018-2231-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wei Li
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Liang Yuan
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Guojun Tong
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Youhua He
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Yue Meng
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Song Hao
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Jianting Chen
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Jun Guo
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, 02114, USA
| | | | - Dehong Yang
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
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17
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Li WL, Yu X, Huang ZP, Pang QJ. Effect of parathyroid hormone on healing in osteoporotic fractures via a phospholipase C-independent pathway. J Int Med Res 2017; 45:1200-1207. [PMID: 28534698 PMCID: PMC5536420 DOI: 10.1177/0300060517707075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Objective This study was performed to investigate the effect of parathyroid hormone (PTH) on healing in osteoporotic fractures via a phospholipase C (PLC)-independent pathway and explore the mechanism of PTH-mediated bone formation. Methods Ninety-six 12-week-old C57BL/6J female mice underwent bilateral ovariectomy. One month later, the lower third of the femur was fractured and the mice were treated using saline, PTH(1-28), PTH(1-34), zoledronic acid (ZA), PTH(1-28)+ZA, and PTH(1-34)+ZA. The mice were killed at weeks 2 and 4 in each group. Biomechanical testing and micro-computed tomography were performed. Results The formation and strength of the callus increased in all but the saline group. The mice treated with PTH(1-34) showed a significantly higher ultimate bending force, bending rigidity, bone mineral density, percent bone volume, and trabecular thickness than those treated with PTH(1-28). The PTH(1-34)+ZA group demonstrated the greatest improvements in the ultimate bending force, bending rigidity, bone mineral density, and relative bone volume. Conclusions PTH can promote fracture healing and callus hardness in ovariectomized mice by increasing callus formation and reconstructing trabecular bone via a PLC-independent pathway. PTH combined with ZA has a cumulative effect on the healing of fractures in ovariectomized mice.
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Affiliation(s)
- Wei-Long Li
- 1 Ningbo University School of Medicine, Ningbo, China
| | - Xiao Yu
- 2 Department of Orthopedics, Ningbo No. 2 Hospital, Ningbo, China
| | - Zhi-Ping Huang
- 3 Department of Spinal Surgery, Nanfang Hospital, Southern University, Guangzhou, China
| | - Qing-Jiang Pang
- 2 Department of Orthopedics, Ningbo No. 2 Hospital, Ningbo, China
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18
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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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19
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Tong G, Meng Y, Hao S, Hu S, He Y, Yan W, Yang D. Parathyroid Hormone Activates Phospholipase C (PLC)-Independent Protein Kinase C Signaling Pathway via Protein Kinase A (PKA)-Dependent Mechanism: A New Defined Signaling Route Would Induce Alternative Consideration to Previous Conceptions. Med Sci Monit 2017; 23:1896-1906. [PMID: 28424452 PMCID: PMC5407178 DOI: 10.12659/msm.903699] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Background Parathyroid hormone (PTH) is an effective anti-osteoporosis agent, after binding to its receptor PTHR1, several signaling pathways, including cAMP/protein kinase A (PKA) and phospholipase C (PLC)/protein kinase C (PKC), are initiated through G proteins; with the cAMP/PKA pathway as the major pathway. Earlier studies have reported that PTHR1 might also activate PKC via a PLC-independent mechanism, but this pathway remains unclear. Material/Methods In HEK293 cells, cAMP accumulation was measured with ELISA and PKC was measured with fluorescence resonance energy transfer (FRET) analysis using CKAR plasmid. In MC3T3-E1 cells, real-time PCR was performed to examine gene expressions. Then assays for cell apoptosis, cell differentiation, alkaline phosphatase activity, and mineralization were performed. Results The FRET analysis found that PTH(1–34), [G1,R19]PTH(1–34) (GR(1–34), and [G1,R19]PTH(1–28) (GR(1–28) were all activated by PKC. The PKC activation ability of GR(1–28) was blocked by cAMP inhibitor (Rp-cAMP) and rescued with the addition of active PKA-α and PKA-β. The PKC activation ability of GR(1–34) was partially inhibited by Rp-cAMP. In MC3T3-E1 cells, gene expressions of ALP, CITED1, NR4a2, and OSX that was regulated by GR(1–28) were significantly changed by the pan-PKC inhibitor Go6983. After pretreatment with Rp-cAMP, the gene expressions of ALP, CITED1, and OPG were differentially regulated by GR(1–28) or GR(1–34), and the difference was blunted by Go6983. PTH(1–34), GR(1–28), and GR(1–34) significantly decreased early apoptosis and augmented osteoblastic differentiation in accordance with the activities of PKA and PKC. Conclusions PLC-independent PKC activation induced by PTH could be divided into two potential mechanisms: one was PKA-dependent and associated with PTH(1–28); the other was PKA-independent and associated with PTH(29–34). We also found that PTH could activate PLC-independent PKC via PKA-dependent mechanisms.
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Affiliation(s)
- Guojun Tong
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China (mainland)
| | - Yue Meng
- Department of Joint Surgery, The Fifth Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong, China (mainland)
| | - Song Hao
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China (mainland)
| | - Shaoyu Hu
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China (mainland)
| | - Youhua He
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China (mainland)
| | - Wenjuan Yan
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China (mainland)
| | - Dehong Yang
- Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China (mainland)
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20
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Pountos I, Panteli M, Lampropoulos A, Jones E, Calori GM, Giannoudis PV. The role of peptides in bone healing and regeneration: a systematic review. BMC Med 2016; 14:103. [PMID: 27400961 PMCID: PMC4940902 DOI: 10.1186/s12916-016-0646-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Bone tissue engineering and the research surrounding peptides has expanded significantly over the last few decades. Several peptides have been shown to support and stimulate the bone healing response and have been proposed as therapeutic vehicles for clinical use. The aim of this comprehensive review is to present the clinical and experimental studies analysing the potential role of peptides for bone healing and bone regeneration. METHODS A systematic review according to PRISMA guidelines was conducted. Articles presenting peptides capable of exerting an upregulatory effect on osteoprogenitor cells and bone healing were included in the study. RESULTS Based on the available literature, a significant amount of experimental in vitro and in vivo evidence exists. Several peptides were found to upregulate the bone healing response in experimental models and could act as potential candidates for future clinical applications. However, from the available peptides that reached the level of clinical trials, the presented results are limited. CONCLUSION Further research is desirable to shed more light into the processes governing the osteoprogenitor cellular responses. With further advances in the field of biomimetic materials and scaffolds, new treatment modalities for bone repair will emerge.
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Affiliation(s)
- Ippokratis Pountos
- Department of Trauma & Orthopaedics, School of Medicine, University of Leeds, Leeds, UK
| | - Michalis Panteli
- Department of Trauma & Orthopaedics, School of Medicine, University of Leeds, Leeds, UK
| | | | - Elena Jones
- Unit of Musculoskeletal Disease, Leeds Institute of Rheumatic and Musculoskeletal Medicine, St. James University Hospital, University of Leeds, LS9 7TF, Leeds, UK
| | - Giorgio Maria Calori
- Department of Trauma & Orthopaedics, School of Medicine, ISTITUTO ORTOPEDICO GAETANO PINI, Milan, Italy
| | - Peter V Giannoudis
- Department of Trauma & Orthopaedics, School of Medicine, University of Leeds, Leeds, UK. .,NIHR Leeds Biomedical Research Unit, Chapel Allerton Hospital, LS7 4SA Leeds, West Yorkshire, Leeds, UK.
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Martin TJ. Parathyroid Hormone-Related Protein, Its Regulation of Cartilage and Bone Development, and Role in Treating Bone Diseases. Physiol Rev 2016; 96:831-71. [DOI: 10.1152/physrev.00031.2015] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Although parathyroid hormone-related protein (PTHrP) was discovered as a cancer-derived hormone, it has been revealed as an important paracrine/autocrine regulator in many tissues, where its effects are context dependent. Thus its location and action in the vasculature explained decades-long observations that injection of PTH into animals rapidly lowered blood pressure by producing vasodilatation. Its roles have been specified in development and maturity in cartilage and bone as a crucial regulator of endochondral bone formation and bone remodeling, respectively. Although it shares actions with parathyroid hormone (PTH) through the use of their common receptor, PTHR1, PTHrP has other actions mediated by regions within the molecule beyond the amino-terminal sequence that resembles PTH, including the ability to promote placental transfer of calcium from mother to fetus. A striking feature of the physiology of PTHrP is that it possesses structural features that equip it to be transported in and out of the nucleus, and makes use of a specific nuclear import mechanism to do so. Evidence from mouse genetic experiments shows that PTHrP generated locally in bone is essential for normal bone remodeling. Whereas the main physiological function of PTH is the hormonal regulation of calcium metabolism, locally generated PTHrP is the important physiological mediator of bone remodeling postnatally. Thus the use of intermittent injection of PTH as an anabolic therapy for bone appears to be a pharmacological application of the physiological function of PTHrP. There is much current interest in the possibility of developing PTHrP analogs that might enhance the therapeutic anabolic effects.
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Affiliation(s)
- T. John Martin
- St Vincent's Institute of Medical Research, Department of Medicine, University of Melbourne, St Vincent's Hospital, Melbourne, Australia
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22
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Kong L, Zhao YP, Tian QY, Feng JQ, Kobayashi T, Merregaert J, Liu CJ. Extracellular matrix protein 1, a direct targeting molecule of parathyroid hormone-related peptide, negatively regulates chondrogenesis and endochondral ossification via associating with progranulin growth factor. FASEB J 2016; 30:2741-54. [PMID: 27075243 DOI: 10.1096/fj.201600261r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 04/05/2016] [Indexed: 01/16/2023]
Abstract
Chondrogenesis and endochondral ossification are precisely controlled by cellular interactions with surrounding matrix proteins and growth factors that mediate cellular signaling pathways. Here, we report that extracellular matrix protein 1 (ECM1) is a previously unrecognized regulator of chondrogenesis. ECM1 is induced in the course of chondrogenesis and its expression in chondrocytes strictly depends on parathyroid hormone-related peptide (PTHrP) signaling pathway. Overexpression of ECM1 suppresses, whereas suppression of ECM1 enhances, chondrocyte differentiation and hypertrophy in vitro and ex vivo In addition, target transgene of ECM1 in chondrocytes or osteoblasts in mice leads to striking defects in cartilage development and endochondral bone formation. Of importance, ECM1 seems to be critical for PTHrP action in chondrogenesis, as blockage of ECM1 nearly abolishes PTHrP regulation of chondrocyte hypertrophy, and overexpression of ECM1 rescues disorganized growth plates of PTHrP-null mice. Furthermore, ECM1 and progranulin chondrogenic growth factor constitute an interaction network and act in concert in the regulation of chondrogenesis.-Kong, L., Zhao, Y.-P., Tian, Q.-Y., Feng, J.-Q., Kobayashi, T., Merregaert, J., Liu, C.-J. Extracellular matrix protein 1, a direct targeting molecule of parathyroid hormone-related peptide, negatively regulates chondrogenesis and endochondral ossification via associating with progranulin growth factor.
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Affiliation(s)
- Li Kong
- Department of Orthopedic Surgery, New York University School of Medicine, New York, New York, USA
| | - Yun-Peng Zhao
- Department of Orthopedic Surgery, New York University School of Medicine, New York, New York, USA
| | - Qing-Yun Tian
- Department of Orthopedic Surgery, New York University School of Medicine, New York, New York, USA
| | - Jian-Quan Feng
- Department of Biomedical Sciences, Texas A&M Baylor College of Dentistry, Dallas, Texas, USA
| | - Tatsuya Kobayashi
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Joseph Merregaert
- Laboratory of Molecular Biotechnology, University of Antwerp, Antwerp, Belgium
| | - Chuan-Ju Liu
- Department of Orthopedic Surgery, New York University School of Medicine, New York, New York, USA; Department of Cell Biology, New York University School of Medicine, New York, New York, USA
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23
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Amso Z, Cornish J, Brimble MA. Short Anabolic Peptides for Bone Growth. Med Res Rev 2016; 36:579-640. [DOI: 10.1002/med.21388] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 01/24/2016] [Accepted: 02/15/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Zaid Amso
- School of Chemical Sciences; The University of Auckland, 23 Symonds St; Auckland 1142 New Zealand
| | - Jillian Cornish
- Department of Medicine; The University of Auckland; Auckland 1010 New Zealand
| | - Margaret A. Brimble
- School of Chemical Sciences; The University of Auckland, 23 Symonds St; Auckland 1142 New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences; The University of Auckland; Auckland 1142 New Zealand
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Onal M, St John HC, Danielson AL, Pike JW. Deletion of the Distal Tnfsf11 RL-D2 Enhancer That Contributes to PTH-Mediated RANKL Expression in Osteoblast Lineage Cells Results in a High Bone Mass Phenotype in Mice. J Bone Miner Res 2016; 31:416-29. [PMID: 26332516 PMCID: PMC4835217 DOI: 10.1002/jbmr.2698] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 08/24/2015] [Accepted: 08/27/2015] [Indexed: 12/24/2022]
Abstract
Receptor activator of nuclear factor-κB ligand (RANKL) is a tumor necrosis factor (TNF)-like cytokine that is necessary for osteoclast formation and survival. Elevated RANKL synthesis is associated with both increased osteoclast number and bone resorption. Earlier studies identified an enhancer 76 kb upstream of the Tnfsf11 transcriptional start site (TSS) termed RL-D5 or the distal control region (DCR) that modulates RANKL expression in response to PTH, 1,25(OH)2D3,, and an array of cytokines. Mice lacking RL-D5 exhibit high bone mass associated with decreased RANKL expression in bone, spleen, and thymus. In addition to RL-D5, genome-wide studies have identified 9 additional Tnfsf11 enhancers residing upstream of the gene's TSS, which provide RANKL cell type-specificity and responsiveness to local and systemic factors. ChIP-chip analyses has revealed inducible vitamin D receptor (VDR) and cAMP response element-binding protein (CREB) binding at an enhancer termed RL-D2 23 kb upstream of the Tnfsf11 TSS in osteoblastic ST2 cells. Herein, we use ChIP-seq analyses to confirm this finding and then delete this enhancer from the mouse genome to determine its physiological role in vivo. RL-D2(-/-) primary stromal cells showed decreased RANKL-induction by both forskolin and 1,25(OH)2D3 ex vivo. Consistent with this, the parathyroid hormone (PTH) induction of RANKL expression was significantly blunted in RL-D2(-/-) mice in vivo. In contrast, lack of RL-D2 had no effect on 1,25(OH)2D3 induction of RANKL in vivo. Similar to the results found in RL-D5(-/-) mice, lack of RL-D2 led to decreased skeletal RANKL expression, resulting in decreased osteoclast numbers and a progressive increase in bone mineral density. Lack of RL-D2 increased cancellous bone mass in femur and spine but did not alter femoral cortical bone thickness. These results highlight the role of distal enhancers in the regulation of RANKL expression by PTH and perhaps 1,25(OH)2D3 and suggest that the RL-D2 and RL-D5 enhancers contribute in either an additive or synergistic manner to regulate bone remodeling.
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Affiliation(s)
- Melda Onal
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Hillary C St John
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Allison L Danielson
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - J Wesley Pike
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
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Lieben L, Verlinden L, Masuyama R, Torrekens S, Moermans K, Schoonjans L, Carmeliet P, Carmeliet G. Extra-intestinal calcium handling contributes to normal serum calcium levels when intestinal calcium absorption is suboptimal. Bone 2015; 81:502-512. [PMID: 26319498 DOI: 10.1016/j.bone.2015.08.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 08/18/2015] [Accepted: 08/20/2015] [Indexed: 01/01/2023]
Abstract
The active form of vitamin D, 1,25(OH)2D, is a crucial regulator of calcium homeostasis, especially through stimulation of intestinal calcium transport. Lack of intestinal vitamin D receptor (VDR) signaling does however not result in hypocalcemia, because the increased 1,25(OH)2D levels stimulate calcium handling in extra-intestinal tissues. Systemic VDR deficiency, on the other hand, results in hypocalcemia because calcium handling is impaired not only in the intestine, but also in kidney and bone. It remains however unclear whether low intestinal VDR activity, as observed during aging, is sufficient for intestinal calcium transport and for mineral and bone homeostasis. To this end, we generated mice that expressed the Vdr exclusively in the gut, but at reduced levels. We found that ~15% of intestinal VDR expression greatly prevented the Vdr null phenotype in young-adult mice, including the severe hypocalcemia. Serum calcium levels were, however, in the low-normal range, which may be due to the suboptimal intestinal calcium absorption, renal calcium loss, insufficient increase in bone resorption and normal calcium incorporation in the bone matrix. In conclusion, our results indicate that low intestinal VDR levels improve intestinal calcium absorption compared to Vdr null mice, but also show that 1,25(OH)2D-mediated fine-tuning of renal calcium reabsorption and bone mineralization and resorption is required to maintain fully normal serum calcium levels.
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Affiliation(s)
- Liesbet Lieben
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Lieve Verlinden
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Ritsuko Masuyama
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Sophie Torrekens
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Karen Moermans
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Luc Schoonjans
- Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, Department of Oncology, KU Leuven, Leuven, Belgium; Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, VIB, KU Leuven, Leuven, Belgium
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, Department of Oncology, KU Leuven, Leuven, Belgium; Laboratory of Angiogenesis and Neurovascular link, Vesalius Research Center, VIB, KU Leuven, Leuven, Belgium
| | - Geert Carmeliet
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium.
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Sinha P, Aarnisalo P, Chubb R, Poulton IJ, Guo J, Nachtrab G, Kimura T, Swami S, Saeed H, Chen M, Weinstein LS, Schipani E, Sims NA, Kronenberg HM, Wu JY. Loss of Gsα in the Postnatal Skeleton Leads to Low Bone Mass and a Blunted Response to Anabolic Parathyroid Hormone Therapy. J Biol Chem 2015; 291:1631-1642. [PMID: 26598522 DOI: 10.1074/jbc.m115.679753] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Indexed: 12/25/2022] Open
Abstract
Parathyroid hormone (PTH) is an important regulator of osteoblast function and is the only anabolic therapy currently approved for treatment of osteoporosis. The PTH receptor (PTH1R) is a G protein-coupled receptor that signals via multiple G proteins including Gsα. Mice expressing a constitutively active mutant PTH1R exhibited a dramatic increase in trabecular bone that was dependent upon expression of Gsα in the osteoblast lineage. Postnatal removal of Gsα in the osteoblast lineage (P-Gsα(OsxKO) mice) yielded markedly reduced trabecular and cortical bone mass. Treatment with anabolic PTH(1-34) (80 μg/kg/day) for 4 weeks failed to increase trabecular bone volume or cortical thickness in male and female P-Gsα(OsxKO) mice. Surprisingly, in both male and female mice, PTH administration significantly increased osteoblast numbers and bone formation rate in both control and P-Gsα(OsxKO) mice. In mice that express a mutated PTH1R that activates adenylyl cyclase and protein kinase A (PKA) via Gsα but not phospholipase C via Gq/11 (D/D mice), PTH significantly enhanced bone formation, indicating that phospholipase C activation is not required for increased bone turnover in response to PTH. Therefore, although the anabolic effect of intermittent PTH treatment on trabecular bone volume is blunted by deletion of Gsα in osteoblasts, PTH can stimulate osteoblast differentiation and bone formation. Together these findings suggest that alternative signaling pathways beyond Gsα and Gq/11 act downstream of PTH on osteoblast differentiation.
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Affiliation(s)
- Partha Sinha
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Piia Aarnisalo
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114,; Department of Clinical Chemistry, University of Helsinki and Helsinki University Central Hospital, Hospital District of Helsinki and Uusimaa, Laboratory Services, HUSLAB, 00029 HUS, Finland
| | - Rhiannon Chubb
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Ingrid J Poulton
- St. Vincent's Institute and Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Jun Guo
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Gregory Nachtrab
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Takaharu Kimura
- Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305
| | - Srilatha Swami
- Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305
| | - Hamid Saeed
- Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305
| | - Min Chen
- Metabolic Diseases Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Lee S Weinstein
- Metabolic Diseases Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Ernestina Schipani
- Departments of Orthopedic Surgery and Medicine, University of Michigan, Ann Arbor, Michigan 48109
| | - Natalie A Sims
- St. Vincent's Institute and Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Henry M Kronenberg
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Joy Y Wu
- From the Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114,; Division of Endocrinology, Stanford University School of Medicine, Stanford, California 94305,.
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27
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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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Wei JS, Zeng R, Chen SY, Lin H, Wu SK, Zheng JC. Effects of aspirin on fracture healing in OPF rats. ASIAN PAC J TROP MED 2015; 7:801-5. [PMID: 25129464 DOI: 10.1016/s1995-7645(14)60140-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 05/15/2014] [Accepted: 07/15/2014] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES To study the effect of aspirin on healing process of osteoporotic fracture (OPF) in rats. METHODS A total of 50 female Wistar rats aged 3 months were randomly divided into observation group and control group, castration method was adopted to establish the osteoporosis (OP) model. After artificial preparing fractures on the midpoint of left femur, fixing gram needle intramedullary, OPF modeling was complete. Aspirin lavage of 33 mg once a day was adopted in observation group after modeling, same amount of normal saline was used in the control as placebo. From each group, selected 5 rats at the 2nd, 4th, 8th and 12th week after modeling to measure the bone mineral density (BMD) and histological examination of the fracture callus, radiology observation was conducted at the 8th and 12th week. Left femur biomechanical measurement was taken at the 12th week. RESULTS BMD values of observation group at each time point were significantly higher than that of the control group after modeling (P<0.05); Histological observation showed that at the 8th week, the endochondral ossification process of observation group was faster than that of observation group, with fuzzy fracture line in observation group and clear fracture line in observation group; at the 12th week, fracture line disappeared in observation group, fracture line of the control group was fuzzy at the same time; three-point bending load of the left femur in observation group rats was significantly higher than that of control group after 12 weeks (P<0.05). CONCLUSIONS Aspirin can accelerate the healing of new callus in OPF rats, increase bone density and biomechanics strength, and promote fracture healing of osteoporotic rats.
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Affiliation(s)
- Jin-Song Wei
- Department of Orthopaedics, Guangdong Medical University Affiliated Hospital, Zhanjiang, Guangdong 524001, China
| | - Rong Zeng
- Department of Orthopaedics, Guangdong Medical University Affiliated Hospital, Zhanjiang, Guangdong 524001, China.
| | - Si-Yuan Chen
- Department of Orthopaedics, Guangdong Medical University Affiliated Hospital, Zhanjiang, Guangdong 524001, China
| | - Hao Lin
- Department of Orthopaedics, Guangdong Medical University Affiliated Hospital, Zhanjiang, Guangdong 524001, China
| | - Shao-Ke Wu
- Department of Orthopaedics, Guangdong Medical University Affiliated Hospital, Zhanjiang, Guangdong 524001, China
| | - Jin-Chang Zheng
- Department of Orthopaedics, Guangdong Medical University Affiliated Hospital, Zhanjiang, Guangdong 524001, China
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29
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Li C, Wang W, Xie L, Luo X, Cao X, Wan M. Lipoprotein receptor-related protein 6 is required for parathyroid hormone-induced Sost suppression. Ann N Y Acad Sci 2015; 1364:62-73. [PMID: 25847683 DOI: 10.1111/nyas.12750] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/02/2015] [Accepted: 02/19/2015] [Indexed: 02/05/2023]
Abstract
Parathyroid hormone (PTH) suppresses the expression of the bone formation inhibitor sclerostin (Sost) in osteocytes by inducing nuclear accumulation of histone deacetylases (HDACs) to inhibit the myocyte enhancer factor 2 (MEF2)-dependent Sost bone enhancer. Previous studies revealed that lipoprotein receptor-related protein 6 (LRP6) mediates the intracellular signaling activation and the anabolic bone effect of PTH. Here, we investigated whether LRP6 mediates the inhibitory effect of PTH on Sost using an osteoblast-specific Lrp6-knockout (LRP6-KO) mouse model. An increased level of Sost mRNA expression was detected in femur tissue from LRP6-KO mice, compared to wild-type littermates. The number of osteocytes expressing sclerostin protein was also increased in bone tissue of LRP6-KO littermates, indicating a negative regulatory role of LRP6 on Sost/sclerostin. In wild-type littermates, intermittent PTH treatment significantly suppressed Sost mRNA expression in bone and the number of sclerostin(+) osteocytes, while the effect of PTH was much less significant in LRP6-KO mice. Additionally, PTH-induced downregulation of MEF2C and 2D, as well as HDAC changes in osteocytes, were abrogated in LRP6-KO mice. These data indicate that LRP6 is required for PTH suppression of Sost expression.
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Affiliation(s)
- Changjun Li
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Institute of Endocrinology and Metabolism, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Weishan Wang
- Department of Orthopaedics, Medical College of Shihezi University, Shihezi, Xinjiang, China
| | - Liang Xie
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.,State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Xianghang Luo
- Institute of Endocrinology and Metabolism, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xu Cao
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mei Wan
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Abstract
Phosphate is essential for growth and maintenance of the skeleton and for generating high-energy phosphate compounds. Evolutionary adaptation to high dietary phosphorous in humans and other terrestrial vertebrates involves regulated mechanisms assuring the efficient renal elimination of excess phosphate. These mechanisms prominently include PTH, FGF23, and Vitamin D, which directly and indirectly regulate phosphate transport. Disordered phosphate homeostasis is associated with pathologies ranging from kidney stones to kidney failure. Chronic kidney disease results in hyperphosphatemia, an elevated calcium×phosphate product with considerable morbidity and mortality, mostly associated with adverse cardiovascular events. This chapter highlights recent findings and insights regarding the hormonal regulation of renal phosphate transport along with imbalances of phosphate balance due to acquired or inherited diseases states.
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31
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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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Li D, Opas EE, Tuluc F, Metzger DL, Hou C, Hakonarson H, Levine MA. Autosomal dominant hypoparathyroidism caused by germline mutation in GNA11: phenotypic and molecular characterization. J Clin Endocrinol Metab 2014; 99:E1774-83. [PMID: 24823460 PMCID: PMC4154081 DOI: 10.1210/jc.2014-1029] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
CONTEXT Most cases of autosomal dominant hypoparathyroidism (ADH) are caused by gain-of-function mutations in CASR or dominant inhibitor mutations in GCM2 or PTH. OBJECTIVE Our objectives were to identify the genetic basis for ADH in a multigenerational family and define the underlying disease mechanism. SUBJECTS Here we evaluated a multigenerational family with ADH in which affected subjects had normal sequences in these genes and were shorter than unaffected family members. METHODS We collected clinical and biochemical data from 6 of 11 affected subjects and performed whole-exome sequence analysis on DNA from two affected sisters and their affected father. Functional studies were performed after expression of wild-type and mutant Gα11 proteins in human embryonic kidney-293-CaR cells that stably express calcium-sensing receptors. RESULTS Whole-exome-sequencing followed by Sanger sequencing revealed a heterozygous mutation, c.179G>T; p.R60L, in GNA11, which encodes the α-subunit of G11, the principal heterotrimeric G protein that couples calcium-sensing receptors to signal activation in parathyroid cells. Functional studies of Gα11 R60L showed increased accumulation of intracellular concentration of free calcium in response to extracellular concentration of free calcium with a significantly decreased EC50 compared with wild-type Gα11. By contrast, R60L was significantly less effective than the oncogenic Q209L form of Gα11 as an activator of the MAPK pathway. Compared to subjects with CASR mutations, patients with GNA11 mutations lacked hypercalciuria and had normal serum magnesium levels. CONCLUSIONS Our findings indicate that the germline gain-of-function mutation of GNA11 is a cause of ADH and implicate a novel role for GNA11 in skeletal growth.
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Affiliation(s)
- Dong Li
- Center for Applied Genomics (D.L., C.H., H.H.), Division of Endocrinology and Diabetes (E.E.O., M.A.L.), Division of Allergy and Immunology (F.T.), Division of Pulmonary Medicine (H.H.), and Center for Bone Health (M.A.L.), The Children's Hospital of Philadelphia; and Department of Pediatrics (H.H., M.A.L.), University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104; and Endocrinology and Diabetes Unit (D.L.M.), British Columbia Children's Hospital, and Department of Pediatrics (D.L.M.), University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4
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33
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Abstract
The etiology of skeletal disease is driven by genetic and environmental factors. Genome-wide association studies (GWAS) of osteoporotic phenotypes have identified novel candidate genes, but have only uncovered a small proportion of the trait variance explained. This "missing heritability" is caused by several factors, including the failure to consider gene-by-environmental (G*E) interactions. Some G*E interactions have been investigated, but new approaches to integrate environmental data into genomic studies are needed. Advances in genotyping and meta-analysis techniques now allow combining genotype data from multiple studies, but the measurement of key environmental factors in large human cohorts still lags behind, as do the statistical tools needed to incorporate these measures in genome-wide association meta-studies. This review focuses on discussing ways to enhance G*E interaction studies in humans and how the use of rodent models can inform genetic studies. Understanding G*E interactions will provide opportunities to effectively target intervention strategies for individualized therapy.
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34
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Guo J, Song L, Liu M, Segawa H, Miyamoto KI, Bringhurst FR, Kronenberg HM, Jüppner H. Activation of a non-cAMP/PKA signaling pathway downstream of the PTH/PTHrP receptor is essential for a sustained hypophosphatemic response to PTH infusion in male mice. Endocrinology 2013; 154:1680-9. [PMID: 23515284 PMCID: PMC3628020 DOI: 10.1210/en.2012-2240] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
PTH increases urinary Pi excretion by reducing expression of two renal cotransporters [NaPi-IIa (Npt2a) and NaPi-IIc (Npt2c)]. In contrast to acute transporter regulation that is cAMP/protein kinase A dependent, long-term effects require phospholipase C (PLC) signaling by the PTH/PTHrP receptor (PPR). To determine whether the latter pathway regulates Pi through Npt2a and/or Npt2c, wild-type mice (Wt) and animals expressing a mutant PPR incapable of PLC activation (DD) were tested in the absence of one (Npt2a(-/-) or Npt2c(-/-)) or both phosphate transporters (2a/2c-dko). PTH infusion for 8 days caused a rapid and persistent decrease in serum Pi in Wt mice, whereas serum Pi in DD mice fell only transiently for the first 2 days. Consistent with these findings, fractional Pi excretion index was increased initially in both animals, but this increase persisted only when the PPR Wt was present. The hypophosphatemic response to PTH infusion was impaired only slightly in PPR Wt/Npt2c(-/-) or DD/Npt2c(-/-) mice. Despite lower baselines, PTH infusion in PPR Wt/Npt2a(-/-) mice decreased serum Pi further, an effect that was attenuated in DD/Npt2a(-/-) mice. Continuous PTH had no effect on serum Pi in 2a/2c-dko mice. PTH administration increased serum 1,25 dihydroxyvitamin D3 levels in Wt and DD mice and increased levels above the elevated baseline with ablation of either but not of both transporters. Continuous PTH elevated serum fibroblast growth factor 23 and blood Ca(2+) equivalently in all groups of mice. Our data indicate that PLC signaling at the PPR contributes to the long-term effect of PTH on Pi homeostasis but not to the regulation of 1,25 dihydroxyvitamin D3, fibroblast growth factor 23, or blood Ca(2+).
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MESH Headings
- Animals
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Hypophosphatemia/chemically induced
- Hypophosphatemia/genetics
- Hypophosphatemia/metabolism
- Infusions, Intravenous
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mutation/physiology
- Parathyroid Hormone/administration & dosage
- Parathyroid Hormone/adverse effects
- Parathyroid Hormone/metabolism
- Receptor, Parathyroid Hormone, Type 1/genetics
- Receptor, Parathyroid Hormone, Type 1/metabolism
- Receptor, Parathyroid Hormone, Type 1/physiology
- Signal Transduction/genetics
- Signal Transduction/physiology
- Sodium-Phosphate Cotransporter Proteins, Type IIa/genetics
- Sodium-Phosphate Cotransporter Proteins, Type IIa/metabolism
- Sodium-Phosphate Cotransporter Proteins, Type IIc/genetics
- Sodium-Phosphate Cotransporter Proteins, Type IIc/metabolism
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Affiliation(s)
- Jun Guo
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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35
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Cupp ME, Nayak SK, Adem AS, Thomsen WJ. Parathyroid hormone (PTH) and PTH-related peptide domains contributing to activation of different PTH receptor-mediated signaling pathways. J Pharmacol Exp Ther 2013; 345:404-18. [PMID: 23516330 DOI: 10.1124/jpet.112.199752] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP), acting through the osteoblast PTH1 receptor (PTH1R), play important roles in bone remodeling. Intermittent administration of PTH(1-34) (teriparatide) leads to bone formation, whereas continuous administration paradoxically leads to bone resorption. Activation of PTH1R promotes regulation of multiple signaling pathways, including G(s)/cAMP/protein kinase A, G(q)/calcium/protein kinase C, β-arrestin recruitment, and extracellular signal-related kinase (ERK)1/2 phosphorylation, as well as receptor internalization, but their role in promoting anabolic and catabolic actions of PTH(1-34) are unclear. In the present investigation, a collection of PTH(1-34) and PTHrP(1-34) peptide analogs were evaluated in orthogonal human PTH1R (hPTH1R) functional assays capturing G(s)- and G(q)-signaling, β-arrestin recruitment, ERK1/2 phosphorylation, and receptor internalization to further define the patterns of PTH1R signaling that they stimulate and further establish peptide domains contributing to agonist activity. Results indicate that both N- and C-terminal domains of PTH and PTHrP are critical for activation of signaling pathways. However, modifications of both regions lead to more substantial decreases in agonist potency and efficacy to stimulate G(q)-signaling, β-arrestin recruitment, ERK1/2 phosphorylation, and receptor internalization than to stimulate G(s)-signaling. The substantial contribution of the peptide C-terminal domain in activation of hPTH1R signaling suggests a role in positioning of the peptide N-terminal region into the receptor J-domain. Several PTH and PTHrP peptides evaluated in this study promote different patterns of biased agonist signaling and may serve as useful tools to further elucidate therapeutically relevant PTH1R signaling in osteoblasts. With a better understanding of therapeutically relevant signaling, novel biased peptides with desired signaling could be designed for safer and more effective treatment of osteoporosis.
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Affiliation(s)
- Meghan E Cupp
- Center for Cancer and Metabolic Diseases, SRI International, 140 Research Drive, Harrisonburg, VA 22802, USA
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Phospholipases of mineralization competent cells and matrix vesicles: roles in physiological and pathological mineralizations. Int J Mol Sci 2013; 14:5036-129. [PMID: 23455471 PMCID: PMC3634480 DOI: 10.3390/ijms14035036] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 02/08/2023] Open
Abstract
The present review aims to systematically and critically analyze the current knowledge on phospholipases and their role in physiological and pathological mineralization undertaken by mineralization competent cells. Cellular lipid metabolism plays an important role in biological mineralization. The physiological mechanisms of mineralization are likely to take place in tissues other than in bones and teeth under specific pathological conditions. For instance, vascular calcification in arteries of patients with renal failure, diabetes mellitus or atherosclerosis recapitulates the mechanisms of bone formation. Osteoporosis—a bone resorbing disease—and rheumatoid arthritis originating from the inflammation in the synovium are also affected by cellular lipid metabolism. The focus is on the lipid metabolism due to the effects of dietary lipids on bone health. These and other phenomena indicate that phospholipases may participate in bone remodelling as evidenced by their expression in smooth muscle cells, in bone forming osteoblasts, chondrocytes and in bone resorbing osteoclasts. Among various enzymes involved, phospholipases A1 or A2, phospholipase C, phospholipase D, autotaxin and sphingomyelinase are engaged in membrane lipid remodelling during early stages of mineralization and cell maturation in mineralization-competent cells. Numerous experimental evidences suggested that phospholipases exert their action at various stages of mineralization by affecting intracellular signaling and cell differentiation. The lipid metabolites—such as arachidonic acid, lysophospholipids, and sphingosine-1-phosphate are involved in cell signaling and inflammation reactions. Phospholipases are also important members of the cellular machinery engaged in matrix vesicle (MV) biogenesis and exocytosis. They may favour mineral formation inside MVs, may catalyse MV membrane breakdown necessary for the release of mineral deposits into extracellular matrix (ECM), or participate in hydrolysis of ECM. The biological functions of phospholipases are discussed from the perspective of animal and cellular knockout models, as well as disease implications, development of potent inhibitors and therapeutic interventions.
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Physiology and emerging biochemistry of the glucagon-like peptide-1 receptor. EXPERIMENTAL DIABETES RESEARCH 2012; 2012:470851. [PMID: 22666230 PMCID: PMC3359799 DOI: 10.1155/2012/470851] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Accepted: 01/25/2012] [Indexed: 12/16/2022]
Abstract
The glucagon-like peptide-1 (GLP-1) receptor is one of the best validated therapeutic targets for the treatment of type 2 diabetes mellitus (T2DM). Over several years, the accumulation of basic, translational, and clinical research helped define the physiologic roles of GLP-1 and its receptor in regulating glucose homeostasis and energy metabolism. These efforts provided much of the foundation for pharmaceutical development of the GLP-1 receptor peptide agonists, exenatide and liraglutide, as novel medicines for patients suffering from T2DM. Now, much attention is focused on better understanding the molecular mechanisms involved in ligand induced signaling of the GLP-1 receptor. For example, advancements in biophysical and structural biology techniques are being applied in attempts to more precisely determine ligand binding and receptor occupancy characteristics at the atomic level. These efforts should better inform three-dimensional modeling of the GLP-1 receptor that will help inspire more rational approaches to identify and optimize small molecule agonists or allosteric modulators targeting the GLP-1 receptor. This article reviews GLP-1 receptor physiology with an emphasis on GLP-1 induced signaling mechanisms in order to highlight new molecular strategies that help determine desired pharmacologic characteristics for guiding development of future nonpeptide GLP-1 receptor activators.
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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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Baron R, Hesse E. Update on bone anabolics in osteoporosis treatment: rationale, current status, and perspectives. J Clin Endocrinol Metab 2012; 97:311-25. [PMID: 22238383 PMCID: PMC3275361 DOI: 10.1210/jc.2011-2332] [Citation(s) in RCA: 243] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Osteoporosis is defined as low bone mineral density associated with skeletal fractures secondary to minimal or no trauma, most often involving the spine, the hip, and the forearm. The decrease in bone mineral density is the consequence of an unbalanced bone remodeling process, with higher bone resorption than bone formation. Osteoporosis affects predominantly postmenopausal women, but also older men. This chronic disease represents a considerable medical and socioeconomic burden for modern societies. The therapeutic options for the treatment of osteoporosis have so far comprised mostly antiresorptive drugs, in particular bisphosphonates and more recently denosumab, but also calcitonin and, for women, estrogens or selective estrogen receptor modulators. These drugs have limitations, however, in particular the fact that they lead to a low turnover state where bone formation decreases with the decrease in bone-remodeling activity. In this review, we discuss the alternative class of osteoporosis drugs, i.e. bone anabolics, their biology, and the perspectives they offer for our therapeutic armamentarium. We focus on the two main osteoanabolic pathways identified as of today: PTH, the only anabolic drug currently on the market; and activation of canonical Wnt signaling through inhibition of the endogenous inhibitors sclerostin and dickkopf1. Each approach is based on a different molecular mechanism, but most recent evidence suggests that these two pathways may actually converge, at least in part. Whereas recombinant human PTH treatment is being revisited with different formulations and attempts to regulate endogenous PTH secretion via the calcium-sensing receptor, antibodies to sclerostin and dickkopf1 are currently in clinical trials and may prove to be even more efficient at increasing bone mass, possibly independent of bone turnover. Each of these anabolic approaches has its own limitations and safety issues, but the prospects of effective anabolic therapy for osteoporosis are indeed bright.
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Affiliation(s)
- Roland Baron
- Department of Medicine, Harvard Medical School, Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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Yuan Q, Sato T, Densmore M, Saito H, Schüler C, Erben RG, Lanske B. FGF-23/Klotho signaling is not essential for the phosphaturic and anabolic functions of PTH. J Bone Miner Res 2011; 26:2026-35. [PMID: 21590742 PMCID: PMC4343543 DOI: 10.1002/jbmr.433] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Parathyroid hormone (PTH) is widely recognized as a key regulator of mineral ion homeostasis. Daily intermittent administration of PTH is the only currently available anabolic therapy for bone disorders such as osteoporosis. Recent studies have shown that PTH increases transcription and secretion of fibroblast growth factor 23 (FGF-23), another important regulator of phosphate homeostasis and skeletal metabolism. However, the full relationship between PTH and FGF-23 is largely unknown. This study evaluated the effect of FGF-23/Klotho signaling on the phosphaturic and anabolic functions of PTH. Eight-day-old wild-type (WT) Fgf23(-/-) and Kl(-/-) mice were injected with 100 µg/kg PTH(1-34) or vehicle daily for a 2-week-period and then euthanized. Intermittent injection of PTH successfully reduced the serum phosphate levels and reversed the hyperphosphatemia of Fgf23(-/-) and Kl(-/-) mice. Bone changes were analyzed in the distal femur metaphysis by peripheral quantitative computed tomography (pQCT), micro-computed tomography (µCT), and histomorphometry. PTH treatment induced substantial increases in bone mineral density (BMD) and trabecular bone volume in each mouse genotype. Expression of osteoblastic marker genes, including Runx2, Col1, Alp, Ocn, and Sost, was similarly altered. In addition, primary osteoblasts were isolated and treated with 100 nM PTH in vitro. PTH treatment similarly induced cAMP accumulation and phosphorylation of ERK1/2 and CREB in the osteoblasts from each genotype. Taken together, our results demonstrate that FGF-23/Klotho signaling is not essential for the phosphaturic and anabolic functions of PTH, suggesting that PTH can function as a therapeutic agent to improve the skeletal quality of patients even in the presence of abnormal serum FGF-23 levels.
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Affiliation(s)
- Quan Yuan
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
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Datta NS. Osteoporotic fracture and parathyroid hormone. World J Orthop 2011; 2:67-74. [PMID: 22474638 PMCID: PMC3302045 DOI: 10.5312/wjo.v2.i8.67] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/19/2011] [Accepted: 06/01/2011] [Indexed: 02/06/2023] Open
Abstract
Osteoporosis and age-related bone loss is associated with changes in bone remodeling characterized by decreased bone formation relative to bone resorption, resulting in bone fragility and increased risk of fractures. Stimulating the function of bone-forming osteoblasts, is the preferred pharmacological intervention for osteoporosis. Recombinant parathyroid hormone (PTH), PTH(1-34), is an anabolic agent with proven benefits to bone strength and has been characterized as a potential therapy for skeletal repair. In spite of PTH's clinical use, safety is a major consideration for long-term treatment. Studies have demonstrated that intermittent PTH treatment enhances and accelerates the skeletal repair process via a number of mechanisms. Recent research into the molecular mechanism of PTH action on bone tissue has led to the development of PTH analogs to control osteoporotic fractures. This review summarizes a number of advances made in the field of PTH and bone fracture to combat these injuries in humans and in animal models. The ultimate goal of providing an alternative to PTH, currently the sole anabolic therapy in clinical use, to promote bone formation and improve bone strength in the aging population is yet to be achieved.
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Abstract
At least 2 different types of cells, hematopoietic and mesenchymal, are present in the adult bone marrow, in addition to endothelial cells. Hematopoietic and mesenchymal cells are believed to originate from hematopoietic stem cells (HSC) and mesenchymal stem cells (MSC), respectively. The bone marrow stroma, a cellular microenvironment that supports HSC, is composed of non-hematopoietic cells and contains MSC. A unique expansion of the bone marrow stroma, also known as marrow fibrosis, is the hallmark of a variety of disorders including hyperparathyroidism and fibrous dysplasia. PTH is the first bone anabolic agent approved by US Food and Drug Administration for the treatment of osteoporosis. Recent studies have suggested that PTH treatment may affect the number of hematopoietic stem cells in the bone marrow and their mobilization into the bloodstream. In addition, cells with classical features of mesenchymal stem cells/progenitors have been shown to express receptors for PTH, and to increase in number and undergo redistribution in the adult bone marrow upon PTH treatment. In this review, we will summarize the up-to-date knowledge on PTH and its relation to stem cells. We will also discuss the contribution of different cell types to the development of marrow fibrosis and the involvement of PTH signaling in this pathology.
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Affiliation(s)
- M Ohishi
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
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Jilka RL, Almeida M, Ambrogini E, Han L, Roberson PK, Weinstein RS, Manolagas SC. Decreased oxidative stress and greater bone anabolism in the aged, when compared to the young, murine skeleton with parathyroid hormone administration. Aging Cell 2010; 9:851-67. [PMID: 20698835 DOI: 10.1111/j.1474-9726.2010.00616.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Because of recent insights into the pathogenesis of age-related bone loss, we investigated whether intermittent parathyroid hormone (PTH) administration antagonizes the molecular mechanisms of the adverse effects of aging on bone. Parathyroid hormone produced a greater increase in vertebral trabecular bone mineral density and bone volume as well as a greater expansion of the endocortical bone surface in the femur of 26- when compared to 6 -month-old female C57BL/6 mice. Moreover, PTH increased trabecular connectivity in vertebrae, and the toughness of both vertebrae and femora in old, but not young, mice. Parathyroid hormone also increased the rate of bone formation and reduced osteoblast apoptosis to a greater extent in the old mice. Most strikingly, PTH reduced reactive oxygen species, p66(Shc) phosphorylation, and expression of the lipoxygenase Alox15, and it increased glutathione and stimulated Wnt signaling in bone of old mice. Parathyroid hormone also antagonized the effects of oxidative stress on p66(Shc) phosphorylation, Forkhead Box O transcriptional activity, osteoblast apoptosis, and Wnt signaling in vitro. In contrast, administration of the antioxidants N-acetyl cysteine or pegylated catalase reduced osteoblast progenitors and attenuated proliferation and Wnt signaling. These results suggest that PTH has a greater bone anabolic efficacy in old age because in addition to its other positive actions on bone formation, it antagonizes the age-associated increase in oxidative stress and its adverse effects on the birth and survival of osteoblasts. On the other hand, ordinary antioxidants cannot restore bone mass in old age because they slow remodeling and attenuate osteoblastogenesis by interfering with Wnt signaling.
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Affiliation(s)
- Robert L Jilka
- Center for Osteoporosis and Metabolic Bone Diseases, University of Arkansas for Medical Sciences, Little Rock, 72205, USA.
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