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Miura Y, Senoo A, Doura T, Kiyonaka S. Chemogenetics of cell surface receptors: beyond genetic and pharmacological approaches. RSC Chem Biol 2022; 3:269-287. [PMID: 35359495 PMCID: PMC8905536 DOI: 10.1039/d1cb00195g] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 01/20/2022] [Indexed: 11/29/2022] Open
Abstract
Cell surface receptors transmit extracellular information into cells. Spatiotemporal regulation of receptor signaling is crucial for cellular functions, and dysregulation of signaling causes various diseases. Thus, it is highly desired to control receptor functions with high spatial and/or temporal resolution. Conventionally, genetic engineering or chemical ligands have been used to control receptor functions in cells. As the alternative, chemogenetics has been proposed, in which target proteins are genetically engineered to interact with a designed chemical partner with high selectivity. The engineered receptor dissects the function of one receptor member among a highly homologous receptor family in a cell-specific manner. Notably, some chemogenetic strategies have been used to reveal the receptor signaling of target cells in living animals. In this review, we summarize the developing chemogenetic methods of transmembrane receptors for cell-specific regulation of receptor signaling. We also discuss the prospects of chemogenetics for clinical applications.
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Affiliation(s)
- Yuta Miura
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University Nagoya 464-8603 Japan
| | - Akinobu Senoo
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University Nagoya 464-8603 Japan
| | - Tomohiro Doura
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University Nagoya 464-8603 Japan
| | - Shigeki Kiyonaka
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University Nagoya 464-8603 Japan
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2
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Nottmeier C, Liao N, Simon A, Decker MG, Luther J, Schweizer M, Yorgan T, Kaucka M, Bockamp E, Kahl-Nieke B, Amling M, Schinke T, Petersen J, Koehne T. Wnt1 Promotes Cementum and Alveolar Bone Growth in a Time-Dependent Manner. J Dent Res 2021; 100:1501-1509. [PMID: 34009051 PMCID: PMC8649456 DOI: 10.1177/00220345211012386] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The WNT/β-catenin signaling pathway plays a central role in the biology
of the periodontium, yet the function of specific extracellular WNT
ligands remains poorly understood. By using a
Wnt1-inducible transgenic mouse model targeting
Col1a1-expressing alveolar osteoblasts,
odontoblasts, and cementoblasts, we demonstrate that the WNT ligand
WNT1 is a strong promoter of cementum and alveolar bone formation in
vivo. We induced Wnt1 expression for 1, 3, or 9 wk in
Wnt1Tg mice and analyzed them at the age of 6 wk and 12 wk.
Micro–computed tomography (CT) analyses of the mandibles revealed a
1.8-fold increased bone volume after 1 and 3 wk of
Wnt1 expression and a 3-fold increased bone
volume after 9 wk of Wnt1 expression compared to
controls. In addition, the alveolar ridges were higher in Wnt1Tg mice
as compared to controls. Nondecalcified histology demonstrated
increased acellular cementum thickness and cellular cementum volume
after 3 and 9 wk of Wnt1 expression. However, 9 wk of
Wnt1 expression was also associated with
periodontal breakdown and ectopic mineralization of the pulp. The
composition of this ectopic matrix was comparable to those of cellular
cementum as demonstrated by quantitative backscattered electron
imaging and immunohistochemistry for noncollagenous proteins. Our
analyses of 52-wk-old mice after 9 wk of Wnt1
expression revealed that Wnt1 expression affects
mandibular bone and growing incisors but not molar teeth, indicating
that Wnt1 influences only growing tissues. To further
investigate the effect of Wnt1 on cementoblasts, we
stably transfected the cementoblast cell line (OCCM-30) with a vector
expressing Wnt1-HA and performed proliferation as
well as differentiation experiments. These experiments demonstrated
that Wnt1 promotes proliferation but not
differentiation of cementoblasts. Taken together, our findings
identify, for the first time, Wnt1 as a critical
regulator of alveolar bone and cementum formation, as well as provide
important insights for harnessing the WNT signal pathway in
regenerative dentistry.
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Affiliation(s)
- C Nottmeier
- Department of Orthodontics, University Medical Center Hamburg, Hamburg, Germany.,Department of Orthodontics, University of Leipzig Medical Center, Leipzig, Germany
| | - N Liao
- Department of Orthodontics, University Medical Center Hamburg, Hamburg, Germany.,Department of Orthodontics, College of Stomatology, North China University of Science and Technology, Tangshan, China
| | - A Simon
- Department of Orthodontics, University Medical Center Hamburg, Hamburg, Germany
| | - M G Decker
- Department of Orthodontics, University Medical Center Hamburg, Hamburg, Germany
| | - J Luther
- Department of Osteology and Biomechanics, University Medical Center Hamburg, Hamburg, Germany
| | - M Schweizer
- ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - T Yorgan
- Department of Osteology and Biomechanics, University Medical Center Hamburg, Hamburg, Germany
| | - M Kaucka
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - E Bockamp
- Institute for Translational Immunology and Research Center for Immunotherapy, University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - B Kahl-Nieke
- Department of Orthodontics, University Medical Center Hamburg, Hamburg, Germany
| | - M Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg, Hamburg, Germany
| | - T Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg, Hamburg, Germany
| | - J Petersen
- Department of Orthodontics, University of Leipzig Medical Center, Leipzig, Germany.,Department of Osteology and Biomechanics, University Medical Center Hamburg, Hamburg, Germany
| | - T Koehne
- Department of Orthodontics, University Medical Center Hamburg, Hamburg, Germany.,Department of Orthodontics, University of Leipzig Medical Center, Leipzig, Germany
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3
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Barre R, Beton N, Batut A, Accabled F, Sales de Gauzy J, Auriol F, Eddiry S, Tauber M, Laurencin S, Salles JP, Gennero I. Ghrelin uses the GHS-R1a/Gi/cAMP pathway and induces differentiation only in mature osteoblasts. This ghrelin pathway is impaired in AIS patients. Biochem Biophys Rep 2020; 24:100782. [PMID: 32984555 PMCID: PMC7494670 DOI: 10.1016/j.bbrep.2020.100782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/09/2020] [Accepted: 07/13/2020] [Indexed: 12/27/2022] Open
Abstract
We have examined the Acylated Ghrelin (AG)/Gi pathway in different human osteoblastic cell lines. We have found that: 1) AG induces differentiation/mineralization only in mature osteoblasts; 2) the expression of GHS-R1a increases up to the mature cell stage, 3) the action is mediated via the GHS-R/Gi/cAMP pathway only in mature osteoblasts, and 4) osteoblastic cells from adolescent idiopathic scoliosis (AIS) are resistant to the AG/Gi/cAMP pathway. Altogether, these results suggested that AG uses the GHS-R1a/Gi/cAMP pathway to induce differentiation in mature osteoblasts only. This pathway is impaired in AIS osteoblasts. Understanding AG-specific pathways involved in normal and pathological osteoblasts may be useful for developing new treatments for pathologies such as AIS or osteoporosis.
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Affiliation(s)
- Ronan Barre
- Oral Biology Department, Faculty of Odontology, Paul Sabatier Toulouse III University, France
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
| | - Nicolas Beton
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
- Faculty of Medicine, Paul Sabatier Toulouse III University, France
| | - Aurélie Batut
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
- Faculty of Medicine, Paul Sabatier Toulouse III University, France
| | - Frank Accabled
- Faculty of Medicine, Paul Sabatier Toulouse III University, France
- Orthopedic Department, Children Hospital, CHU Toulouse, France
| | - Jerome Sales de Gauzy
- Faculty of Medicine, Paul Sabatier Toulouse III University, France
- Orthopedic Department, Children Hospital, CHU Toulouse, France
| | - Françoise Auriol
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
- Endocrinology and Bone Pathologies Department, Children Hospital, CHU Toulouse, France
| | - Sanaa Eddiry
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
- Endocrinology and Bone Pathologies Department, Children Hospital, CHU Toulouse, France
| | - Maithe Tauber
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
- Faculty of Medicine, Paul Sabatier Toulouse III University, France
- Endocrinology and Bone Pathologies Department, Children Hospital, CHU Toulouse, France
| | - Sara Laurencin
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
- Periodontology Department, Faculty of Odontology, Paul Sabatier Toulouse III University, France
| | - Jean Pierre Salles
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
- Faculty of Medicine, Paul Sabatier Toulouse III University, France
- Endocrinology and Bone Pathologies Department, Children Hospital, CHU Toulouse, France
| | - Isabelle Gennero
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, CHU Toulouse, France
- Faculty of Medicine, Paul Sabatier Toulouse III University, France
- Clinical Biochemistry Department, Federative Institute of Biology, CHU Toulouse, France
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4
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Li Z, Liu T, Gilmore A, Gómez NM, Mitchell CH, Li YP, Oursler MJ, Yang S. Regulator of G Protein Signaling Protein 12 (Rgs12) Controls Mouse Osteoblast Differentiation via Calcium Channel/Oscillation and Gαi-ERK Signaling. J Bone Miner Res 2019; 34:752-764. [PMID: 30489658 PMCID: PMC7675783 DOI: 10.1002/jbmr.3645] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 11/13/2018] [Accepted: 11/17/2018] [Indexed: 12/11/2022]
Abstract
Bone homeostasis intimately relies on the balance between osteoblasts (OBs) and osteoclasts (OCs). Our previous studies have revealed that regulator of G protein signaling protein 12 (Rgs12), the largest protein in the Rgs super family, is essential for osteoclastogenesis from hematopoietic cells and OC precursors. However, how Rgs12 regulates OB differentiation and function is still unknown. To understand that, we generated an OB-targeted Rgs12 conditional knockout (CKO) mice model by crossing Rgs12fl/fl mice with Osterix (Osx)-Cre transgenic mice. We found that Rgs12 was highly expressed in both OB precursor cells (OPCs) and OBs of wild-type (WT) mice, and gradually increased during OB differentiation, whereas Rgs12-CKO mice (OsxCre/+ ; Rgs12fl/fl ) exhibited a dramatic decrease in both trabecular and cortical bone mass, with reduced numbers of OBs and increased apoptotic cell population. Loss of Rgs12 in OPCs in vitro significantly inhibited OB differentiation and the expression of OB marker genes, resulting in suppression of OB maturation and mineralization. Further mechanism study showed that deletion of Rgs12 in OPCs significantly inhibited guanosine triphosphatase (GTPase) activity and cyclic adenosine monophosphate (cAMP) level, and impaired Calcium (Ca2+ ) oscillations via restraints of major Ca2+ entry sources (extracellular Ca2+ influx and intracellular Ca2+ release from endoplasmic reticulum), partially contributed by the blockage of L-type Ca2+ channel mediated Ca2+ influx. Downstream mediator extracellular signal-related protein kinase (ERK) was found inactive in OBs of OsxCre/+ ; Rgs12fl/fl mice and in OPCs after Rgs12 deletion, whereas application of pertussis toxin (PTX) or overexpression of Rgs12 could rescue the defective OB differentiation via restoration of ERK phosphorylation. Our findings reveal that Rgs12 is an important regulator during osteogenesis and highlight Rgs12 as a potential therapeutic target for bone disorders. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Ziqing Li
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Tongjun Liu
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
- Department of Implantology, Shandong Provincial Key Laboratory of Oral Biomedicine, School of Stomatology, Shandong University
- Department of Stomatology, the Jinan Central Hospital Affiliated to Shandong University, Jinan, Shandong province 250000, China
| | - Alyssa Gilmore
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
| | - Néstor Más Gómez
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Claire H Mitchell
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
- Department of Physiology, School of Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Yi-ping Li
- Department of Pathology, University of Alabama in Birmingham, Birmingham, AL 35294, USA
| | - Merry J Oursler
- Department of Medicine, Endocrine Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Shuying Yang
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
- The Penn Center for Musculoskeletal Disorders, University of Pennsylvania Philadelphia, PA 19104, USA
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
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5
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6
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Abstract
Pharmacology, the chemical control of physiology, emerged as an offshoot of physiology when the physiologists using chemicals to probe physiological systems became more interested in the probes than the systems. Pharmacologists were always, and in many ways still are, bound to study drugs in systems they do not fully understand. Under these circumstances, null methods were the main ways in which conclusions about biologically active molecules were made. However, as understanding of the basic mechanisms of cellular function and biochemical systems were elucidated, so too did the understanding of how drugs affected these systems. Over the past 20 years, new ideas have emerged in the field that have completely changed and revitalized it; these are described herein. It will be seen how null methods in isolated tissues gave way to, first biochemical radioligand binding studies, and then to a wide array of functional assay technologies that can measure the effects of molecules on drug targets. In addition, the introduction of molecular dynamics, the appreciation of the allosteric nature of receptors, protein X-ray crystal structures, genetic manipulations in the form of knock-out and knock-in systems and Designer Receptors Exclusively Activated by Designer Drugs have revolutionized pharmacology.
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Affiliation(s)
- Terry Kenakin
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
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7
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Abstract
Skeletal development is exquisitely controlled both spatially and temporally by cell signaling networks. Gαs is the stimulatory α-subunit in a heterotrimeric G protein complex transducing the signaling of G-protein-coupled receptors (GPCRs), responsible for controlling both skeletal development and homeostasis. Gαs, encoded by the GNAS gene in humans, plays critical roles in skeletal development and homeostasis by regulating commitment, differentiation and maturation of skeletal cells. Gαs-mediated signaling interacts with the Wnt and Hedgehog signaling pathways, both crucial regulators of skeletal development, remodeling and injury repair. Genetic mutations that disrupt Gαs functions cause human disorders with severe skeletal defects, such as fibrous dysplasia of bone and heterotopic bone formation. This chapter focuses on the crucial roles of Gαs signaling during skeletal development and homeostasis, and the pathological mechanisms underlying skeletal diseases caused by GNAS mutations.
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Affiliation(s)
- Qian Cong
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States
| | - Ruoshi Xu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Cariology and Endodontology, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yingzi Yang
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States.
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8
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Millard SM, Wang L, Wattanachanya L, O'Carroll D, Fields AJ, Pang J, Kazakia G, Lotz JC, Nissenson RA. Role of Osteoblast Gi Signaling in Age-Related Bone Loss in Female Mice. Endocrinology 2017; 158:1715-1726. [PMID: 28407060 PMCID: PMC5460929 DOI: 10.1210/en.2016-1365] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 04/06/2017] [Indexed: 11/19/2022]
Abstract
Age-related bone loss is an important risk factor for fractures in the elderly; it results from an imbalance in bone remodeling mainly due to decreased bone formation. We have previously demonstrated that endogenous G protein-coupled receptor (GPCR)-driven Gi signaling in osteoblasts (Obs) restrains bone formation in mice during growth. Here, we launched a longitudinal study to test the hypothesis that Gi signaling in Obs restrains bone formation in aging mice, thereby promoting bone loss. Our approach was to block Gi signaling in maturing Obs by the induced expression of the catalytic subunit of pertussis toxin (PTX) after the achievement of peak bone mass. In contrast to the progressive cancellous bone loss seen in aging sex-matched littermate control mice, aging female Col1(2.3)+/PTX+ mice showed an age-related increase in bone volume. Increased bone volume was associated with increased bone formation at both trabecular and endocortical surfaces as well as increased bending strength of the femoral middiaphyses. In contrast, male Col1(2.3)+/PTX+ mice were not protected from age-related bone loss. Our results indicate that Gi signaling markedly restrains bone formation at cancellous and endosteal bone surfaces in female mice during aging. Blockade of the relevant Gi-coupled GPCRs represents an approach for the development of osteoporosis therapies-at least in the long bones of aging women.
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Affiliation(s)
- Susan M Millard
- Endocrine Research Unit, VA Medical Center, San Francisco, California 94158
| | - Liping Wang
- Endocrine Research Unit, VA Medical Center, San Francisco, California 94158
- Department of Medicine and Physiology, University of California, San Francisco, California 94158
| | | | - Dylan O'Carroll
- Endocrine Research Unit, VA Medical Center, San Francisco, California 94158
| | - Aaron J Fields
- Department of Orthopedic Surgery, University of California, San Francisco, California 94158
| | - Joyce Pang
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143
| | - Galateia Kazakia
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143
| | - Jeffrey C Lotz
- Department of Orthopedic Surgery, University of California, San Francisco, California 94158
| | - Robert A Nissenson
- Endocrine Research Unit, VA Medical Center, San Francisco, California 94158
- Department of Medicine and Physiology, University of California, San Francisco, California 94158
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9
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Bradley SJ, Tobin AB. Design of Next-Generation G Protein-Coupled Receptor Drugs: Linking Novel Pharmacology and In Vivo Animal Models. Annu Rev Pharmacol Toxicol 2016; 56:535-59. [PMID: 26738479 DOI: 10.1146/annurev-pharmtox-011613-140012] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Despite the fact that G protein-coupled receptors (GPCRs) are the most successful drug targets in history, this supergene family of cell surface receptors has yet to be fully exploited as targets in the treatment of human disease. Here, we present optimism that this may change in the future by reviewing the substantial progress made in the understanding of GPCR molecular pharmacology that has generated an extensive toolbox of ligand types that include orthosteric, allosteric, and bitopic ligands, many of which show signaling bias. We discuss how combining these advances with recently described transgenic, chemical genetic, and optogenetic animal models will provide the framework to allow for the rational design of next-generation GPCR drugs that possess increased therapeutic efficacy and decreased adverse/toxic responses.
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Affiliation(s)
- Sophie J Bradley
- MRC Toxicology Unit, University of Leicester, Leicester LE1 9HN United Kingdom; ,
| | - Andrew B Tobin
- MRC Toxicology Unit, University of Leicester, Leicester LE1 9HN United Kingdom; ,
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10
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Choudhary S, Goetjen A, Estus T, Jacome-Galarza CE, Aguila HL, Lorenzo J, Pilbeam C. Serum Amyloid A3 Secreted by Preosteoclasts Inhibits Parathyroid Hormone-stimulated cAMP Signaling in Murine Osteoblasts. J Biol Chem 2015; 291:3882-94. [PMID: 26703472 DOI: 10.1074/jbc.m115.686576] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Indexed: 12/25/2022] Open
Abstract
Continuous parathyroid hormone (PTH) blocks its own osteogenic actions in marrow stromal cell cultures by inducing Cox2 and receptor activator of nuclear factor κB ligand (RANKL) in the osteoblastic lineage cells, which then cause the hematopoietic lineage cells to secrete an inhibitor of PTH-stimulated osteoblast differentiation. To identify this inhibitor, we used bone marrow macrophages (BMMs) and primary osteoblasts (POBs) from WT and Cox2 knock-out (KO) mice. Conditioned medium (CM) from RANKL-treated WT, but not KO, BMMs blocked PTH-stimulated cAMP production in POBs. Inhibition was reversed by pertussis toxin (PTX), which blocks Gαi/o activation. Saa3 was the most highly differentially expressed gene in a microarray comparison of RANKL-treated WT versus Cox2 KO BMMs, and RANKL induced Saa3 protein secretion only from WT BMMs. CM from RANKL-stimulated BMMs with Saa3 knockdown did not inhibit PTH-stimulated responses in POBs. SAA added to POBs inhibited PTH-stimulated cAMP responses, which was reversed by PTX. Selective agonists and antagonists of formyl peptide receptor 2 (Fpr2) suggested that Fpr2 mediated the inhibitory actions of Saa3 on osteoblasts. In BMMs committed to become osteoclasts by RANKL treatment, Saa3 expression peaked prior to appearance of multinucleated cells. Flow sorting of WT marrow revealed that Saa3 was secreted only from the RANKL-stimulated B220(-) CD3(-)CD11b(-/low) CD115(+) preosteoclast population. We conclude that Saa3 secretion from preosteoclasts, induced by RANKL in a Cox2-dependent manner, inhibits PTH-stimulated cAMP signaling and osteoblast differentiation via Gαi/o signaling. The induction of Saa3 by PTH may explain the suppression of bone formation when PTH is applied continuously and may be a new therapeutic target for osteoporosis.
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Affiliation(s)
- Shilpa Choudhary
- New England Musculoskeletal Institute, University of Connecticut Health, Farmington, Connecticut 06030 From the Departments of Medicine and
| | - Alexandra Goetjen
- New England Musculoskeletal Institute, University of Connecticut Health, Farmington, Connecticut 06030
| | - Thomas Estus
- New England Musculoskeletal Institute, University of Connecticut Health, Farmington, Connecticut 06030
| | | | | | - Joseph Lorenzo
- New England Musculoskeletal Institute, University of Connecticut Health, Farmington, Connecticut 06030 From the Departments of Medicine and
| | - Carol Pilbeam
- New England Musculoskeletal Institute, University of Connecticut Health, Farmington, Connecticut 06030 From the Departments of Medicine and
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11
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Wang L, Hsiao EC, Lieu S, Scott M, O'Carroll D, Urrutia A, Conklin BR, Colnot C, Nissenson RA. Loss of Gi G-Protein-Coupled Receptor Signaling in Osteoblasts Accelerates Bone Fracture Healing. J Bone Miner Res 2015; 30:1896-904. [PMID: 25917236 DOI: 10.1002/jbmr.2540] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 04/08/2015] [Accepted: 04/21/2015] [Indexed: 12/24/2022]
Abstract
G-protein-coupled receptors (GPCRs) are key regulators of skeletal homeostasis and are likely important in fracture healing. Because GPCRs can activate multiple signaling pathways simultaneously, we used targeted disruption of G(i) -GPCR or activation of G(s) -GPCR pathways to test how each pathway functions in the skeleton. We previously demonstrated that blockade of G(i) signaling by pertussis toxin (PTX) transgene expression in maturing osteoblastic cells enhanced cortical and trabecular bone formation and prevented age-related bone loss in female mice. In addition, activation of G(s) signaling by expressing the G(s) -coupled engineered receptor Rs1 in maturing osteoblastic cells induced massive trabecular bone formation but cortical bone loss. Here, we test our hypothesis that the G(i) and G(s) pathways also have distinct functions in fracture repair. We applied closed, nonstabilized tibial fractures to mice in which endogenous G(i) signaling was inhibited by PTX, or to mice with activated G(s) signaling mediated by Rs1. Blockade of endogenous G(i) resulted in a smaller callus but increased bone formation in both young and old mice. PTX treatment decreased expression of Dkk1 and increased Lef1 mRNAs during fracture healing, suggesting a role for endogenous G(i) signaling in maintaining Dkk1 expression and suppressing Wnt signaling. In contrast, adult mice with activated Gs signaling showed a slight increase in the initial callus size with increased callus bone formation. These results show that G(i) blockade and G(s) activation of the same osteoblastic lineage cell can induce different biological responses during fracture healing. Our findings also show that manipulating the GPCR/cAMP signaling pathway by selective timing of G(s) and G(i) -GPCR activation may be important for optimizing fracture repair.
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Affiliation(s)
- Liping Wang
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA
| | - Edward C Hsiao
- Department of Medicine, the Program in Craniofacial Biology, and the Institute for Human Genetics, University of California, San Francisco, CA
| | - Shirley Lieu
- Department of Orthopedic Surgery, University of California, San Francisco General Hospital, Orthopaedic Trauma Institute, San Francisco, CA
| | - Mark Scott
- Department of Orthopedic Surgery, University of California, San Francisco General Hospital, Orthopaedic Trauma Institute, San Francisco, CA
| | - Dylan O'Carroll
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA
| | - Ashley Urrutia
- Department of Medicine, the Program in Craniofacial Biology, and the Institute for Human Genetics, University of California, San Francisco, CA
| | - Bruce R Conklin
- Department of Medicine, the Program in Craniofacial Biology, and the Institute for Human Genetics, University of California, San Francisco, CA.,Gladstone Institute of Cardiovascular Disease, San Francisco, CA.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA
| | - Celine Colnot
- Department of Orthopedic Surgery, University of California, San Francisco General Hospital, Orthopaedic Trauma Institute, San Francisco, CA.,Institut National de la Santé et de la Recherche Médicale (INSERM; National Institute of Health and Medical Research), Unités Mixtes de Recherche (UMR) 1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Paris, France
| | - Robert A Nissenson
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA
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12
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Wang L, Carroll DO, Liu X, Roth T, Kim H, Halloran B, Nissenson RA. Effects of blockade of endogenous Gi signaling in Tie2-expressing cells on bone formation in a mouse model of heterotopic ossification. J Orthop Res 2015; 33:1212-7. [PMID: 25773760 DOI: 10.1002/jor.22876] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 02/13/2015] [Indexed: 02/04/2023]
Abstract
Available evidence indicates that some Tie2-expressing (Tie2(+) ) cells serve as multipotent progenitors that have robust BMP-dependent osteogenic activity and mediate heterotopic ossification (HO). Since signaling through the G protein Gi is required for cell motility, we hypothesized that blockade of endogenous Gi signaling in Tie2(+) cell populations would prevent HO formation. Blockade of Gi signaling in Tie2(+) cells was accomplished in transgenic mice with expression of pertussis toxin (PTX) under the control of the Tie2 promoter (Tie2(+) /PTX(+) ). Bone formation within HOs was evaluated 2 weeks after BMP injection. Expression of PTX in Tie2(+) cells significantly reduced the bone volume (BV) of HOs in male and female mice. Orthotopic bones were assessed at the distal femur and expression of PTX significantly increased trabecular bone fractional volume and bone formation rate in females only. In adult Tie2(+) /GFP(+) mice, GFP(+) cells appeared both inside and at the surfaces of bone tissue within HOs and in orthotopic bones. In summary, blockade of Gi signaling in Tie2(+) cells reduced the accrual of HOs and stimulated osteogenesis in orthotopic bones. Targeting of Gi protein coupled receptors in Tie2(+) cells may be a novel therapeutic strategy in states of abnormal bone formation such as osteoporosis and HO.
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Affiliation(s)
- Liping Wang
- Endocrine Research Unit, VA Medical Center, San Francisco, 94121, California.,Department of Medicine and Physiology, University of California, San Francisco, 94143, California
| | - Dylan O' Carroll
- Endocrine Research Unit, VA Medical Center, San Francisco, 94121, California
| | - Xuhui Liu
- Department of Orthopedic Surgery, University of California, San Francisco, 94143, California
| | - Theresa Roth
- Endocrine Research Unit, VA Medical Center, San Francisco, 94121, California
| | - Hubert Kim
- Department of Orthopedic Surgery, University of California, San Francisco, 94143, California
| | - Bernard Halloran
- Endocrine Research Unit, VA Medical Center, San Francisco, 94121, California
| | - Robert A Nissenson
- Endocrine Research Unit, VA Medical Center, San Francisco, 94121, California.,Department of Medicine and Physiology, University of California, San Francisco, 94143, California
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Abbott MJ, Roth TM, Ho L, Wang L, O’Carroll D, Nissenson RA. Negative Skeletal Effects of Locally Produced Adiponectin. PLoS One 2015; 10:e0134290. [PMID: 26230337 PMCID: PMC4521914 DOI: 10.1371/journal.pone.0134290] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/07/2015] [Indexed: 01/15/2023] Open
Abstract
Epidemiological studies show that high circulating levels of adiponectin are associated with low bone mineral density. The effect of adiponectin on skeletal homeostasis, on osteoblasts in particular, remains controversial. We investigated this issue using mice with adipocyte-specific over-expression of adiponectin (AdTg). MicroCT and histomorphometric analysis revealed decreases (15%) in fractional bone volume in AdTg mice at the proximal tibia with no changes at the distal femur. Cortical bone thickness at mid-shafts of the tibia and at the tibiofibular junction was reduced (3–4%) in AdTg mice. Dynamic histomorphometry at the proximal tibia in AdTg mice revealed inhibition of bone formation. AdTg mice had increased numbers of adipocytes in close proximity to trabecular bone in the tibia, associated with increased adiponectin levels in tibial marrow. Treatment of BMSCs with adiponectin after initiation of osteoblastic differentiation resulted in reduced mineralized colony formation and reduced expression of mRNA of osteoblastic genes, osterix (70%), Runx2 (52%), alkaline phosphatase (72%), Col1 (74%), and osteocalcin (81%). Adiponectin treatment of differentiating osteoblasts increased expression of the osteoblast genes PPARγ (32%) and C/ebpα (55%) and increased adipocyte colony formation. These data suggest a model in which locally produced adiponectin plays a negative role in regulating skeletal homeostasis through inhibition of bone formation and by promoting an adipogenic phenotype.
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Affiliation(s)
- Marcia J. Abbott
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, United States of America
- Department of Health Sciences and Kinesiology, Crean College of Health and Behavioral Sciences, Chapman University, Orange, CA, United States of America
| | - Theresa M. Roth
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, United States of America
| | - Linh Ho
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, United States of America
| | - Liping Wang
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, United States of America
| | - Dylan O’Carroll
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, United States of America
| | - Robert A. Nissenson
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, United States of America
- * E-mail:
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14
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Wattanachanya L, Wang L, Millard SM, Lu WD, O'Carroll D, Hsiao EC, Conklin BR, Nissenson RA. Assessing the osteoblast transcriptome in a model of enhanced bone formation due to constitutive Gs-G protein signaling in osteoblasts. Exp Cell Res 2015; 333:289-302. [PMID: 25704759 DOI: 10.1016/j.yexcr.2015.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 01/29/2015] [Accepted: 02/11/2015] [Indexed: 12/29/2022]
Abstract
G protein-coupled receptor (GPCR) signaling in osteoblasts (OBs) is an important regulator of bone formation. We previously described a mouse model expressing Rs1, an engineered constitutively active Gs-coupled GPCR, under the control of the 2.3 kb Col I promoter. These mice showed a dramatic age-dependent increase in trabecular bone of femurs. Here, we further evaluated the effects of enhanced Gs signaling in OBs on intramembranous bone formation by examining calvariae of 1- and 9-week-old Col1(2.3)/Rs1 mice and characterized the in vivo gene expression specifically occurring in osteoblasts with activated Gs G protein-coupled receptor signaling, at the cellular level rather than in a whole bone. Rs1 calvariae displayed a dramatic increase in bone volume with partial loss of cortical structure. By immunohistochemistry, Osterix was detected in cells throughout the inter-trabecular space while Osteocalcin was expressed predominantly in cells along bone surfaces, suggesting the role of paracrine mediators secreted from OBs driven by 2.3 kb Col I promoter could influence early OB commitment, differentiation, and/or proliferation. Gene expression analysis of calvarial OBs revealed that genes affected by Rs1 signaling include those encoding proteins important for cell differentiation, cytokines and growth factors, angiogenesis, coagulation, and energy metabolism. The set of Gs-GPCRs and other GPCRs that may contribute to the observed skeletal phenotype and candidate paracrine mediators of the effect of Gs signaling in OBs were also determined. Our results identify novel detailed in vivo cellular changes of the anabolic response of the skeleton to Gs signaling in mature OBs.
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Affiliation(s)
- Lalita Wattanachanya
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA; Division of Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand.
| | - Liping Wang
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
| | - Susan M Millard
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
| | - Wei-Dar Lu
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
| | - Dylan O'Carroll
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
| | - Edward C Hsiao
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Francisco, CA, USA.
| | - Bruce R Conklin
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA, USA; Department of Medicine, University of California, San Francisco, CA, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA.
| | - Robert A Nissenson
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
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Keinan D, Yang S, Cohen RE, Yuan X, Liu T, Li YP. Role of regulator of G protein signaling proteins in bone. Front Biosci (Landmark Ed) 2014; 19:634-48. [PMID: 24389209 DOI: 10.2741/4232] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Regulators of G protein signaling (RGS) proteins are a family with more than 30 proteins that all contain an RGS domain. In the past decade, increasing evidence has indicated that RGS proteins play crucial roles in the regulation of G protein coupling receptors (GPCR), G proteins, and calcium signaling during cell proliferation, migration, and differentiation in a variety of tissues. In bone, those proteins modulate bone development and remodeling by influencing various signaling pathways such as GPCR-G protein signaling, Wnt, calcium oscillations and PTH. This review summarizes the recent advances in the understanding of the regulation of RGS gene expression, as well as the functions and mechanisms of RGS proteins, especially in regulating GPCR-G protein signaling, Wnt signaling, calcium oscillations signaling and PTH signaling during bone development and remodeling. This review also highlights the regulation of different RGS proteins in osteoblasts, chondrocytes and osteoclasts. The knowledge from the recent advances of RGS study summarized in the review would provide the insights into new therapies for bone diseases.
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Affiliation(s)
- David Keinan
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, The State University of New York, 3435 Main Street, Buffalo, NY 14214
| | - Shuying Yang
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, The State University of New York, 3435 Main Street, Buffalo, NY 14214
| | - Robert E Cohen
- Department of Periodontics and Endodontics, School of Dental Medicine, University at Buffalo, The State University of New York, 3435 Main Street, Buffalo, NY, 14214, USA
| | - Xue Yuan
- Department of Oral Biology School of Dental Medicine, University at Buffalo, The State University of New York, B36 Foster Hall, Buffalo, NY 14214
| | - Tongjun Liu
- Department of Oral Biology School of Dental Medicine, University at Buffalo, The State University of New York, B36 Foster Hall, Buffalo, NY 14214
| | - Yi-Ping Li
- Department of Pathology, University of Alabama at Birmingham (UAB), 1825 University Blvd, Birmingham AL 35294, USA
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Sakai N. Principles for the use of in vivo transgene techniques: overview and an introductory practical guide for the selection of tetracycline-controlled transgenic mice. Methods Mol Biol 2014; 1142:33-40. [PMID: 24706272 DOI: 10.1007/978-1-4939-0404-4_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Transgenic mice are a beneficial tool that can allow researchers to investigate the roles of specific genes in physiology and disease. However, conventional transgenic mice have the limitation that constitutive expression of a transgene from the embryonic stage may affect the normal development of the mice or cause compensating effects. To overcome these disadvantages, tetracycline-controlled transgenic mice, which can express target gene products in a tissue-specific and time-dependent manner, have been developed. In this section, the principles of tetracycline-controlled systems are discussed first. In addition, useful information for generating transgenic mice using this system is introduced.
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Affiliation(s)
- Norio Sakai
- Department of Molecular and Pharmacological Neuroscience, Institute of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Minami-ku Kasumi, Hiroshima, 734-8551, Japan,
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Lee HM, Giguere PM, Roth BL. DREADDs: novel tools for drug discovery and development. Drug Discov Today 2013; 19:469-73. [PMID: 24184433 DOI: 10.1016/j.drudis.2013.10.018] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 09/17/2013] [Accepted: 10/25/2013] [Indexed: 12/31/2022]
Abstract
Since the invention of the first designer receptors exclusively activated by designer drugs (DREADDs), these engineered G protein-coupled receptors (GPCRs) have been widely applied in investigations of biological processes and behaviors. DREADD technology has emerged as a powerful tool with great potential for drug discovery and development. DREADDs can facilitate the identification of druggable targets and enable researchers to explore the activities of novel drugs against both known and orphan GPCRs. Here, we discuss how DREADDs can be used as novel tools for drug discovery and development.
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Affiliation(s)
- Hyeong-Min Lee
- Department of Pharmacology, Program in Neuroscience, Division of Chemical Biology and Medicinal Chemistry, and NIMH Psychoactive Drug Screening Program, University of North Carolina, Chapel Hill Medical School, 4072 Genetic Medicine Building, Chapel Hill, NC 27514, USA
| | - Patrick M Giguere
- Department of Pharmacology, Program in Neuroscience, Division of Chemical Biology and Medicinal Chemistry, and NIMH Psychoactive Drug Screening Program, University of North Carolina, Chapel Hill Medical School, 4072 Genetic Medicine Building, Chapel Hill, NC 27514, USA
| | - Bryan L Roth
- Department of Pharmacology, Program in Neuroscience, Division of Chemical Biology and Medicinal Chemistry, and NIMH Psychoactive Drug Screening Program, University of North Carolina, Chapel Hill Medical School, 4072 Genetic Medicine Building, Chapel Hill, NC 27514, USA.
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18
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Kao RS, Abbott MJ, Louie A, O’Carroll D, Lu W, Nissenson R. Constitutive protein kinase A activity in osteocytes and late osteoblasts produces an anabolic effect on bone. Bone 2013; 55:277-87. [PMID: 23583750 PMCID: PMC3690773 DOI: 10.1016/j.bone.2013.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 03/30/2013] [Accepted: 04/02/2013] [Indexed: 11/19/2022]
Abstract
Osteocytes have been implicated in the control of bone formation. However, the signal transduction pathways that regulate the biological function of osteocytes are poorly defined. Limited evidence suggests an important role for the Gs/cAMP pathway in osteocyte function. In the present study, we explored the hypothesis that cAMP-dependent kinase A (PKA) activation in osteocytes plays a key role in controlling skeletal homeostasis. To test this hypothesis, we mated mice harboring a Cre-conditional, mutated PKA catalytic subunit allele that encodes a constitutively active form of PKA (CαR) with mice expressing Cre under the control of the osteocyte-specific promoter, DMP1. This allowed us to direct the expression of CαR to osteocytes in double transgenic progeny. Examination of Cre expression indicated that CαR was also expressed in late osteoblasts. Cortical and trabecular bone parameters from 12-week old mice were determined by μCT. Expression of CαR in osteocytes and late osteoblasts altered the shape of cortical bone proximal to the tibia-fibular junction (TFJ) and produced a significant increase in its size. In trabecular bone of the distal femur, fractional bone volume, trabecular number, and trabecular thickness were increased. These increases were partially the results of increased bone formation rates (BFRs) on the endosteal surface of the cortical bone proximal to the TFJ as well as increased BFR on the trabecular bone surface of the distal femur. Mice expressing CαR displayed a marked increase in the expression of osteoblast markers such as osterix, runx2, collagen 1α1, and alkaline phosphatase (ALP). Interestingly, expression of osteocyte marker gene, DMP1, was significantly up-regulated but the osteocyte number per bone area was not altered. Expression of SOST, a presumed target for PKA signaling in osteocytes, was significantly down-regulated in females. Importantly, no changes in bone resorption were detected. In summary, constitutive PKA signaling in osteocytes and late osteoblasts led to a small expansion of the size of the cortical bone proximal to the TFJ and an increase in trabecular bone in female mice. This was associated with down-regulation of SOST and up-regulation of several osteoblast marker genes. Activation of the PKA pathway in osteocytes and late osteoblasts is sufficient for the initiation of an anabolic skeletal response.
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Affiliation(s)
| | | | | | | | | | - Robert Nissenson
- Corresponding author at: University of California San Francisco, San Francisco, CA, USA. Fax: 415-750-6929.
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19
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Shahnazari M, Chu V, Wronski TJ, Nissenson RA, Halloran BP. CXCL12/CXCR4 signaling in the osteoblast regulates the mesenchymal stem cell and osteoclast lineage populations. FASEB J 2013; 27:3505-13. [PMID: 23704087 DOI: 10.1096/fj.12-225763] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The chemokine CXCL12 and its receptor CXCR4 play a key role in regulation of hematopoietic stem cells and cell migratory function during morphogenesis. Osteoblasts express both the ligand and the receptor, but little is known about the role of CXCL12-CXCR4 signaling in maintaining skeletal homeostasis. Using Cre-Lox technology to delete CXCR4 in mature osteoblasts in mice, we show here a significant decrease in bone mass and alterations in cancellous bone structure. CXCR4 gene ablation increased the number of colony-forming units (CFU), CFU-positive for alkaline phosphatase (CFU-AP(+)), and mineralizing nodules in bone marrow stromal cell (BMSC) cultures. The adipocyte precursor population decreased in BMSCs harvested from the KO animals. The nonadherent population of BMSCs harvested from the long bone diaphysis of KO animals formed more osteoclasts, a finding that was associated with increased circulatory levels of pyridinoline, a marker of bone resorption. Our data show that osteoblast-specific CXCR4 deletion has profound effects on the mesenchymal stem cell pool and allocation to the osteoblastic and adipocytic cell lineages. They also show that CXCL12/CXCR4 signaling in the mature osteoblast can feedback to regulate the osteoclast precursor pool size and play a multifunctional role in regulating bone formation and resorption.
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Affiliation(s)
- Mohammad Shahnazari
- Division of Endocrinology, Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA 94123, USA
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20
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Siegert P, Schmidt G, Papatheodorou P, Wieland T, Aktories K, Orth JHC. Pasteurella multocida toxin prevents osteoblast differentiation by transactivation of the MAP-kinase cascade via the Gα(q/11)--p63RhoGEF--RhoA axis. PLoS Pathog 2013; 9:e1003385. [PMID: 23696743 PMCID: PMC3656108 DOI: 10.1371/journal.ppat.1003385] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 04/11/2013] [Indexed: 11/19/2022] Open
Abstract
The 146-kDa Pasteurella multocida toxin (PMT) is the main virulence factor to induce P. multocida-associated progressive atrophic rhinitis in various animals. PMT leads to a destruction of nasal turbinate bones implicating an effect of the toxin on osteoblasts and/or osteoclasts. The toxin induces constitutive activation of Gα proteins of the Gq/11-, G12/13- and Gi-family by deamidating an essential glutamine residue. To study the PMT effect on bone cells, we used primary osteoblasts derived from rat calvariae and stromal ST-2 cells as differentiation model. As marker of functional osteoblasts the expression and activity of alkaline phosphatase, formation of mineralization nodules or expression of specific transcription factors as osterix was determined. Here, we show that the toxin inhibits differentiation and/or function of osteoblasts by activation of Gαq/11. Subsequently, Gαq/11 activates RhoA via p63RhoGEF, which specifically interacts with Gαq/11 but not with other G proteins like Gα12/13 and Gαi. Activated RhoA transactivates the mitogen-activated protein (MAP) kinase cascade via Rho kinase, involving Ras, MEK and ERK, resulting in inhibition of osteoblast differentiation. PMT-induced inhibition of differentiation was selective for the osteoblast lineage as adipocyte-like differentiation of ST-2 cells was not hampered. The present work provides novel insights, how the bacterial toxin PMT can control osteoblastic development by activating heterotrimeric G proteins of the Gαq/11-family and is a molecular pathogenetic basis for understanding the role of the toxin in bone loss during progressive atrophic rhinitis induced by Pasteurella multocida. Pasteurella multocida causes as a facultative pathogen various diseases in men and animals. One induced syndrome is atrophic rhinitis, which is a form of osteopenia, mainly characterized by facial distortion due to degradation of nasal turbinate bones. Strains, which especially affect bone tissue, produce the protein toxin P. multocida toxin (PMT). Importantly, PMT alone is capable to induce all symptoms of atrophic rhinitis. To cause osteopenia PMT influences the development and/or activity of specialized bone cells like osteoblasts and osteoclasts. Recently, we could identify the molecular mechanism of PMT. The toxin constitutively activates certain heterotrimeric G proteins by deamidation. Here, we studied the effect of PMT on the differentiation of osteoblasts. We demonstrate the direct action of PMT on osteoblasts and osteoblast-like cells and as a consequence inhibition of osteoblastic differentiation. Moreover, we revealed the underlying signal transduction pathway to impair proper osteoblast development. We show that PMT activates small GTPases in a Gαq/11 dependent manner via a non-ubiquitously expressed RhoGEF. In turn the mitogen-activated protein kinase pathway is transactivated leading to inhibition of osteoblastogenesis. Our findings present a mechanism how PMT hijacks host cell signaling pathways to hinder osteoblast development, which contributes to the syndrome of atrophic rhinitis.
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Affiliation(s)
- Peter Siegert
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- Hermann–Staudinger–Graduiertenschule Universität Freiburg, Freiburg, Germany
| | - Gudula Schmidt
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Panagiotis Papatheodorou
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Thomas Wieland
- Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Klaus Aktories
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany
- * E-mail: (KA); (JO)
| | - Joachim H. C. Orth
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
- * E-mail: (KA); (JO)
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Kao R, Lu W, Louie A, Nissenson R. Cyclic AMP signaling in bone marrow stromal cells has reciprocal effects on the ability of mesenchymal stem cells to differentiate into mature osteoblasts versus mature adipocytes. Endocrine 2012; 42:622-36. [PMID: 22695986 PMCID: PMC3509326 DOI: 10.1007/s12020-012-9717-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 05/25/2012] [Indexed: 01/02/2023]
Abstract
Stimulatory G protein-mediated cAMP signaling is intimately involved in skeletal homeostasis. However, limited information is available on the role of the cAMP signaling in regulating the differentiation of mesenchymal stem cells into mature osteoblasts and adipocytes. To investigate this, we treated primary mouse bone marrow stromal cells (BMSCs) with forskolin to stimulate cAMP signaling and determined the effect on osteoblast and adipocyte differentiation. Exposure of differentiating osteoblasts to forskolin markedly inhibited progression to the late stages of osteoblast differentiation, and this effect was replicated by continuous exposure to PTH. Strikingly, forskolin activation of cAMP signaling in BMSCs conditioned mesenchymal stem cells (MSCs) to undergo increased osteogenic differentiation and decreased adipogenic differentiation. PTH treatment of BMSCs also enhanced subsequent osteogenesis, but promoted an increased adipogenesis as well. Thus, activation of cAMP signaling alters the lineage commitment of MSCs, favoring osteogenesis at the expense of adipogenesis.
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Affiliation(s)
- Richard Kao
- University of California, San Francisco, San Francisco, CA USA
- Veterans Affairs Medical Center, San Francisco, CA USA
| | - Weidar Lu
- University of California, San Francisco, San Francisco, CA USA
- Veterans Affairs Medical Center, San Francisco, CA USA
| | - Alyssa Louie
- University of California, San Francisco, San Francisco, CA USA
- Veterans Affairs Medical Center, San Francisco, CA USA
| | - Robert Nissenson
- University of California, San Francisco, San Francisco, CA USA
- Veterans Affairs Medical Center, San Francisco, CA USA
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22
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Salles JP, Laurencin-Dalicieux S, Conte-Auriol F, Briand-Mésange F, Gennero I. Bone defects in LPA receptor genetically modified mice. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:93-8. [PMID: 22867754 DOI: 10.1016/j.bbalip.2012.07.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/20/2012] [Accepted: 07/24/2012] [Indexed: 12/24/2022]
Abstract
LPA and LPA(1) have been shown to increase osteoblastic proliferation and differentiation as well as activation of osteoclasts. Cell and animal model studies have suggested that LPA is produced by bone cells and bone tissues. We obtained data from invalidated mice which support the hypothesis that LPA(1) is involved in bone development by promoting osteogenesis. LPA(1)-invalidated mice demonstrate growth and sternal and costal abnormalities, which highlights the specific roles of LPA(1) during bone development. Microcomputed tomography and histological analysis demonstrate osteoporosis in the trabecular and cortical bone of LPA(1)-invalidated mice. Moreover, bone marrow mesenchymal progenitors from these mice displayed decreased osteoblastic differentiation. Infrared analysis did not indicate osteomalacia in the bone tissue of LPA(1)-invalidated mice. LPA(1) displays opposite effects to LPA(4) on the related G proteins G(i) and G(s), responsible for decrease and increase of the cAMP level respectively, which itself is essential to the control of osteoblastic differentiation. The opposite effects of LPA(1) and LPA(4) during osteoblastic differentiation support the possibility that new pharmacological agents derived from the LPA pathways could be found and used in clinical practice to positively influence bone formation and treat osteoporosis. The paracrine effect of LPA is potentially modulated by its concentration in bone tissues, which may result from various intracellular and extracellular pathways. The relevance of LPA(1) in bone remodeling, as a receptor able to influence both osteoblast and osteoclast activity, still deserves further clarification. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.
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Affiliation(s)
- Jean Pierre Salles
- Unité d'Endocrinologie, Maladies Osseuses, Gynécologie et Génétique, Hôpital des Enfants, Toulouse University Hospital, Toulouse, France.
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Lee MH, Kang JH, Lee SW. The significance of differential expression of genes and proteins in human primary cells caused by microgrooved biomaterial substrata. Biomaterials 2012; 33:3216-34. [PMID: 22285466 DOI: 10.1016/j.biomaterials.2012.01.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Accepted: 01/14/2012] [Indexed: 01/18/2023]
Abstract
We demonstrate that etched microgrooves, with truncated V-shape in cross-section and subsequent acid etching, on titanium substrata alter the expression of various genes and proteins in human primary cells. Etched microgrooves with 30 or 60 μm width and 10 μm depth promoted human gingival fibroblast proliferation and significantly enhanced the osteoblast differentiation of human bone marrow-derived mesenchymal stem cells and human periodontal ligament cells by inducing differential expression of various genes involved in cell adhesion, migration, proliferation, mitosis, cytoskeletal reorganization, translation initiation, vesicular trafficking, proton transportation, transforming growth factor-β signaling, mitogen-activated protein kinase signaling, simvastatin's anabolic effect on bone, inhibitory guanine nucleotide binding protein (G protein)'s action, sumoylation pathway, survival/apoptosis, mitochondrial distribution, type I collagen production, osteoblast differentiation, and bone remodeling that were verified by the differential display PCR and quantitative real-time PCR. The most influential genes on the enhancement of fibroblast proliferation or osteoblast differentiation were determined by multiple regression analysis, and the expression of relevant proteins was confirmed by western blotting and protein quantitation.
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Affiliation(s)
- Myung Hyun Lee
- Green Ceramics Division, Korea Institute of Ceramic Engineering and Technology, 77 10-gil, Digital-ro, Geumcheon-gu, Seoul 153-801, Republic of Korea
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McMullen AB, Baidwan GS, McCarthy KD. Morphological and behavioral changes in the pathogenesis of a novel mouse model of communicating hydrocephalus. PLoS One 2012; 7:e30159. [PMID: 22291910 PMCID: PMC3265463 DOI: 10.1371/journal.pone.0030159] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 12/14/2011] [Indexed: 11/18/2022] Open
Abstract
The Ro1 model of hydrocephalus represents an excellent model for studying the pathogenesis of hydrocephalus due to its complete penetrance and inducibility, enabling the investigation of the earliest cellular and histological changes in hydrocephalus prior to overt pathology. Hematoxylin and eosin staining, immunofluorescence and electron microscopy were used to characterize the histopathological events of hydrocephalus in this model. Additionally, a broad battery of behavioral tests was used to investigate behavioral changes in the Ro1 model of hydrocephalus. The earliest histological changes observed in this model were ventriculomegaly and disorganization of the ependymal lining of the aqueduct of Sylvius, which occurred concomitantly. Ventriculomegaly led to thinning of the ependyma, which was associated with periventricular edema and areas of the ventricular wall void of cilia and microvilli. Ependymal denudation was subsequent to severe ventriculomegaly, suggesting that it is an effect, rather than a cause, of hydrocephalus in the Ro1 model. Additionally, there was no closure of the aqueduct of Sylvius or any blockages within the ventricular system, even with severe ventriculomegaly, suggesting that the Ro1 model represents a model of communicating hydrocephalus. Interestingly, even with severe ventriculomegaly, there were no behavioral changes, suggesting that the brain is able to compensate for the structural changes that occur in the pathogenesis of hydrocephalus if the disorder progresses at a sufficiently slow rate.
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MESH Headings
- Animals
- Behavior, Animal/physiology
- Brain/pathology
- Brain/physiopathology
- Brain/ultrastructure
- Cardiomegaly/pathology
- Cerebral Aqueduct/pathology
- Cerebral Aqueduct/ultrastructure
- Cerebral Ventricles/pathology
- Cerebral Ventricles/ultrastructure
- Disease Models, Animal
- Hydrocephalus/complications
- Hydrocephalus/genetics
- Hydrocephalus/pathology
- Hydrocephalus/physiopathology
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Microscopy, Electron
- Receptors, Opioid, kappa/genetics
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, kappa/physiology
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Affiliation(s)
- Allison B. McMullen
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Gurlal S. Baidwan
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Ken D. McCarthy
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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25
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Kazakia GJ, Speer D, Shanbhag S, Majumdar S, Conklin BR, Nissenson RA, Hsiao EC. Mineral composition is altered by osteoblast expression of an engineered G(s)-coupled receptor. Calcif Tissue Int 2011; 89:10-20. [PMID: 21526395 PMCID: PMC3110278 DOI: 10.1007/s00223-011-9487-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 03/06/2011] [Indexed: 01/22/2023]
Abstract
Activation of the G(s) G protein-coupled receptor Rs1 in osteoblasts increases bone mineral density by 5- to 15-fold in mice and recapitulates histologic aspects of fibrous dysplasia of the bone. However, the effects of constitutive G(s) signaling on bone tissue quality are not known. The goal of this study was to determine bone tissue quality in mice resulting from osteoblast-specific constitutive G(s) activation, by the complementary techniques of FTIR spectroscopy and synchrotron radiation micro-computed tomography (SRμCT). Col1(2.3)-tTA/TetO-Rs1 double transgenic (DT) mice, which showed osteoblast-specific constitutive G(s) signaling activity by the Rs1 receptor, were created. Femora and calvariae of DT and wild-type (WT) mice (6 and 15 weeks old) were analyzed by FTIR spectroscopy. WT and DT femora (3 and 9 weeks old) were imaged by SRμCT. Mineral-to-matrix ratio was 25% lower (P = 0.010), carbonate-to-phosphate ratio was 20% higher (P = 0.025), crystallinity was 4% lower (P = 0.004), and cross-link ratio was 11% lower (P = 0.025) in 6-week DT bone. Differences persisted in 15-week animals. Quantitative SRμCT analysis revealed substantial differences in mean values and heterogeneity of tissue mineral density (TMD). TMD values were 1,156 ± 100 and 711 ± 251 mg/cm(3) (mean ± SD) in WT and DT femoral diaphyses, respectively, at 3 weeks. Similar differences were found in 9-week animals. These results demonstrate that continuous G(s) activation in murine osteoblasts leads to deposition of immature bone tissue with reduced mineralization. Our findings suggest that bone tissue quality may be an important contributor to increased fracture risk in fibrous dysplasia patients.
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Affiliation(s)
- G J Kazakia
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA.
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26
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Millard SM, Louie AM, Wattanachanya L, Wronski TJ, Conklin BR, Nissenson RA. Blockade of receptor-activated G(i) signaling in osteoblasts in vivo leads to site-specific increases in cortical and cancellous bone formation. J Bone Miner Res 2011; 26:822-32. [PMID: 20939063 PMCID: PMC3179326 DOI: 10.1002/jbmr.273] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Osteoblasts play a critical role in the maintenance of bone mass through bone formation and regulation of bone resorption. Targeted expression of a constitutively active engineered G(i)-coupled G protein-coupled receptor (GPCR) to osteoblasts in vivo leads to severe osteopenia. However, little is known about the role of endogenous receptor-mediated G(i) signaling in regulating osteoblast function. In this study, we investigated the skeletal effects of blocking G(i)-coupled signaling in osteoblasts in vivo. This was accomplished by transgenic expression of the catalytic subunit of pertussis toxin (PTX) under control of the collagen Iα 2.3-kb promoter. These mice, designated Col1(2.3)(+)/PTX(+), showed increased cortical thickness at the femoral midshaft at 12 weeks of age. This correlated with increased periosteal bone formation associated with expanded mineralizing surface observed in 8-week-old mice of both genders. The cancellous bone phenotype of the Col1(2.3)(+)/PTX(+) mice was sexually dimorphic, with increases in fractional bone volume at the distal femur seen only in females. Similarly, while cancellous bone-formation rates were unchanged in males, they could not be quantified for female Col1(2.3)(+)/PTX(+) mice owing to the disorganized nature of the labeling pattern, which was consistent with rapid formation of woven bone. Alterations in osteoclast activity did not appear to participate in the phenotype. These data demonstrate that G(i)-coupled signaling by GPCRs endogenous to osteoblasts plays a complex role in the regulation of bone formation in a manner that is dependent on both gender and the anatomic site within bone.
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Affiliation(s)
- Susan M Millard
- Endocrine Research Unit, Veterans Administration Medical Center, University of California San Francisco, San Francisco, CA 94121, USA
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27
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Abstract
A significant challenge for neuroscientists is to determine how both electrical and chemical signals affect the activity of cells and circuits and how the nervous system subsequently translates that activity into behavior. Remote, bidirectional manipulation of those signals with high spatiotemporal precision is an ideal approach to addressing that challenge. Neuroscientists have recently developed a diverse set of tools that permit such experimental manipulation with varying degrees of spatial, temporal, and directional control. These tools use light, peptides, and small molecules to primarily activate ion channels and G protein-coupled receptors (GPCRs) that in turn activate or inhibit neuronal firing. By monitoring the electrophysiological, biochemical, and behavioral effects of such activation/inhibition, researchers can better understand the links between brain activity and behavior. Here, we review the tools that are available for this type of experimentation. We describe the development of the tools and highlight exciting in vivo data. We focus primarily on designer GPCRs (receptors activated solely by synthetic ligands, designer receptors exclusively activated by designer drugs) and microbial opsins (e.g., channelrhodopsin-2, halorhodopsin, Volvox carteri channelrhodopsin) but also describe other novel techniques that use orthogonal receptors, caged ligands, allosteric modulators, and other approaches. These tools differ in the direction of their effect (activation/inhibition, hyperpolarization/depolarization), their onset and offset kinetics (milliseconds/minutes/hours), the degree of spatial resolution they afford, and their invasiveness. Although none of these tools is perfect, each has advantages and disadvantages, which we describe, and they are all still works in progress. We conclude with suggestions for improving upon the existing tools.
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Affiliation(s)
- Sarah C Rogan
- University of North Carolina School of Medicine, Department of Pharmacology, 120 Mason Farm Rd, Chapel Hill, NC 27514, USA
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Hsiao EC, Nguyen TD, Ng JK, Scott MJ, Chang WC, Zahed H, Conklin BR. Constitutive Gs activation using a single-construct tetracycline-inducible expression system in embryonic stem cells and mice. Stem Cell Res Ther 2011; 2:11. [PMID: 21375737 PMCID: PMC3226282 DOI: 10.1186/scrt52] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2010] [Accepted: 03/04/2011] [Indexed: 01/19/2023] Open
Abstract
INTRODUCTION The controlled expression of many genes, including G-protein coupled receptors (GPCRs), is important for delineating gene functions in complex model systems. Binary systems for inducible regulation of transgene expression are widely used in mice. One system is the tTA/TRE expression system, composed of a tetracycline-dependent DNA binding factor and a separate tetracycline operon. However, the requirement for two separate transgenes (one for each tTA or TRE component) makes this system less amenable to models requiring directed cell targeting, increases the risk of multiple transgene integration sites, and requires extensive screening for appropriately-functioning clones. METHODS We developed a single, polycistronic tetracycline-inducible expression platform to control the expression of multiple cistrons in mammalian cells. This platform has three basic constructs: regulator, responder, and destination vectors. The modular platform is compatible with both the TetOff (tTA) and TetOn (rtTA) systems. The modular Gateway recombineering-compatible components facilitate rapidly generating vectors to genetically modify mammalian cells. We apply this system to use the elongation factor 1α (EF1α) promoter to drive doxycycline-regulated expression of both the fluorescent marker mCherry and an engineered Gs-coupled GPCR "Rs1" separated by a 2A ribosomal skip site. RESULTS We show that our combined expression construct drives expression of both the mCherry and Rs1 transgenes in a doxycycline-dependent manner. We successfully target the expression construct into the Rosa26 locus of mouse embryonic stem (ES) cells. Rs1 expression in mouse ES cells increases cAMP accumulation via both basal and ligand-induced Gs mechanisms and is associated with increased embryoid body size. Heterozygous mice carrying the Rs1 expression construct showed normal growth and weight, and developed small increases in bone formation that could be observed in the calvaria. CONCLUSIONS Our results demonstrate the feasibility of a single-vector strategy that combines both the tTA and TRE tetracycline-regulated components for use in cells and mouse models. Although the EF1α promoter is useful for driving expression in pluripotent cells, a single copy of the EF1α promoter did not drive high levels of mCherry and Rs1 expression in the differentiated tissues of adult mice. These findings indicate that promoter selection is an important factor when developing transgene expression models.
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Affiliation(s)
- Edward C Hsiao
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Division of Endocrinology and Metabolism, Department of Medicine, 400 Parnassus Ave., University of California, San Francisco, CA 94143-1222, USA
| | - Trieu D Nguyen
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Jennifer K Ng
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Mark J Scott
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Wei Chun Chang
- Department of Cellular and Molecular Pharmacology, 600 16th Street Rm. S-222, University of California, San Francisco, CA 94158-2140, USA
| | - Hengameh Zahed
- Gladstone Institute of Neurological Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Biomedical Sciences Graduate Program, 513 Parnassus Ave. Rm. HSE-1285, University of California, San Francisco, CA 94158-0505, USA
| | - Bruce R Conklin
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Department of Medicine, 505 Parnassus Ave., University of California, San Francisco, CA 94143, USA
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Abstract
Transgenic mice have had a tremendous impact on biomedical research. Most researchers are familiar with transgenic mice that carry Cre recombinase (Cre) and how they are used to create conditional knockouts. However, some researchers are less familiar with many of the other types of transgenic mice and their applications. For example, transgenic mice can be used to study biochemical and molecular pathways in primary cultures and cell suspensions derived from transgenic mice, cell-cell interactions using multiple fluorescent proteins in the same mouse, and the cell cycle in real time and in the whole animal, and they can be used to perform deep tissue imaging in the whole animal, follow cell lineage during development and disease, and isolate large quantities of a pure cell type directly from organs. These novel transgenic mice and their applications provide the means for studying of molecular and biochemical events in the whole animal that was previously limited to cell cultures. In conclusion, transgenic mice are not just for generating knockouts.
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Affiliation(s)
- R Lance Miller
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Zhou S, Yuan X, Liu Q, Zhang X, Pan X, Zang L, Xu L. BAPTA-AM, an intracellular calcium chelator, inhibits RANKL-induced bone marrow macrophages differentiation through MEK/ERK, p38 MAPK and Akt, but not JNK pathways. Cytokine 2010; 52:210-4. [PMID: 20667748 DOI: 10.1016/j.cyto.2010.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 06/17/2010] [Accepted: 07/02/2010] [Indexed: 10/19/2022]
Abstract
To examine the roles of intracellular calcium in RANKL-induced bone marrow macrophages (BMMs) differentiation, the effects of intracellular calcium chelator BAPTA-AM on RANKL-induced BMMs differentiation, and the activation of its relating signal proteins (MAPKs, and the PI3K/Akt) were studied. BMMs were cultured with various concentrations of BAPTA-AM in the presence of M-CSF (25 ng/ml) and RANKL (25 ng/ml) for 7 days, osteoclastogenic ability, cytosolic free Ca(2+) concentration, osteoclast survival and the expression of phosphorylated ERK1/2, SAPK/JNK, Akt and p38 MAPK were measured by TRAP staining, spectrofluorometer and Western blotting. BAPTA-AM inhibited osteoclastogenesis and osteoclast survival of BMMs by RANKL induction. In osteoclasts without the pretreatment of BAPTA-AM, the increased response of [Ca(2+)](i) was observed within 15 min and the maximum was about 1.2 times that of control. This response was sustained for 30 min and returned to the control level at 1h after RANKL-inducing, and the increased response of [Ca(2+)](i) was completely abolished and sustained to at least 8h by BAPTA-AM. Although immunoblotting data revealed that RANKL could activate the phosphorylation of ERK1/2, SAPK/JNK, Akt and p38 MAPK, the expression of ERK1/2, Akt and p38 MAPK phosphorylation was inhibited by BAPTA-AM dose-dependently. These results revealed that BAPTA-AM inhibit osteoclastogenic ability of BMMs via suppressing the increase of [Ca(2+)](i) which lead to inhibit RANKL-induced the phosphorylation of ERK, Akt and p38 MAPK, but not JNK. This finding may be useful in the development of an osteoclastic inhibitor that targets intracellular signaling factors.
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Affiliation(s)
- Sigui Zhou
- Department of Pharmacology, GuangDong Pharmaceutical University, No. 280 Wai Huan Dong Road, Guangzhou Higher Education Mega Center, Guangzhou, China
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31
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Hsiao EC, Boudignon BM, Halloran BP, Nissenson RA, Conklin BR. Gs G protein-coupled receptor signaling in osteoblasts elicits age-dependent effects on bone formation. J Bone Miner Res 2010; 25:584-93. [PMID: 20200944 PMCID: PMC3153396 DOI: 10.1002/jbmr.3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Age-dependent changes in skeletal growth are important for regulating skeletal expansion and determining peak bone mass. However, how G protein-coupled receptors (GPCRs) regulate these changes is poorly understood. Previously, we described a mouse model expressing Rs1, an engineered receptor with high basal G(s) activity. Rs1 expression in osteoblasts induced a dramatic age-dependent increase in trabecular bone with features resembling fibrous dysplasia. To further investigate how activation of the G(s)-GPCR pathway affects bone formation at different ages, we used the tetracycline-inducible system in the ColI(2.3)(+)/Rs1(+) mouse model to control the timing of Rs1 expression. We found that the Rs1 phenotype developed rapidly between postnatal days 4 and 6, that delayed Rs1 expression resulted in attenuation of the Rs1 phenotype, and that the Rs1-induced bone growth and deformities were markedly reversed when Rs1 expression was suppressed in adult mice. These findings suggest a distinct window of increased osteoblast responsiveness to G(s) signaling during the early postnatal period. In addition, adult bones encode information about their normal shape and structure independently from mechanisms regulating bone expansion. Finally, our model provides a powerful tool for investigating the effects of continuous G(s)-GPCR signaling on dynamic bone growth and remodeling.
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Affiliation(s)
- Edward C Hsiao
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA.
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32
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Hsiao EC, Millard SM, Louie A, Huang Y, Conklin BR, Nissenson RA. Ligand-mediated activation of an engineered gs g protein-coupled receptor in osteoblasts increases trabecular bone formation. Mol Endocrinol 2010; 24:621-31. [PMID: 20150184 DOI: 10.1210/me.2009-0424] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Age-dependent changes in skeletal growth play important roles in regulating skeletal expansion and in the course of many diseases affecting bone. How G protein-coupled receptor (GPCR) signaling affects these changes is poorly understood. Previously, we described a mouse model expressing Rs1, an engineered receptor with constitutive G(s) activity. Rs1 expression in osteoblasts from gestation induced a dramatic age-dependent increase in trabecular bone with features resembling fibrous dysplasia; however, these changes were greatly minimized if Rs1 expression was delayed until after puberty. To further investigate whether ligand-induced activation of the G(s)-GPCR pathway affects bone formation in adult mice, we activated Rs1 in adult mice with the synthetic ligand RS67333 delivered continuously via an osmotic pump or intermittently by daily injections. We found that osteoblasts from adult animals can be stimulated to form large amounts of bone, indicating that adult mice are sensitive to the dramatic bone- forming actions of G(s) signaling in osteoblasts. In addition, our results show that intermittent and continuous activation of Rs1 led to structurally similar but quantitatively different degrees of trabecular bone formation. These results indicate that activation of a G(s)-coupled receptor in osteoblasts of adult animals by either intermittent or continuous ligand administration can increase trabecular bone formation. In addition, osteoblasts located at the bone epiphyses may be more responsive to G(s) signaling than osteoblasts at the bone diaphysis. This model provides a powerful tool for investigating the effects of ligand-activated G(s)-GPCR signaling on dynamic bone growth and remodeling.
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Affiliation(s)
- Edward C Hsiao
- Gladstone Institute of Cardiovascular Disease, 1650 Owens Street, San Francisco, California 94158, USA.
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Nichols CD, Roth BL. Engineered G-protein Coupled Receptors are Powerful Tools to Investigate Biological Processes and Behaviors. Front Mol Neurosci 2009; 2:16. [PMID: 19893765 PMCID: PMC2773177 DOI: 10.3389/neuro.02.016.2009] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 09/12/2009] [Indexed: 12/03/2022] Open
Abstract
Understanding how discreet tissues and neuronal circuits function in relation to the whole organism to regulate physiological processes and behaviors is a fundamental goal of modern biological science. Powerful and important new tools in this discovery process are modified G-protein coupled receptors (GPCRs) known as ‘Receptors Activated Solely by Synthetic Ligands (RASSLs),’ and ‘Designer Receptors Exclusively Activated by a Designer Drug (DREADDs).’ Collectively, these are GPCRs modified either through rational design or directed molecular evolution, that do not respond to native ligand, but functionally respond only to synthetic ligands. Importantly, the utility of these receptors is not limited to examination of the role of GPCR-coupled effector signal transduction pathways. Due to the near ubiquitous expression of GPCRs throughout an organism, this technology, combined with whole animal transgenics to selectively target expression, has the ability to regulate activity of discreet tissues and neuronal circuits through effector pathway modulation to study function and behavior throughout the organism. Advantages over other systems currently used to modify in vivo function include the ability to rapidly, selectively and reversibly manipulate defined signal transduction pathways both in short term and long term studies, and no need for specialized equipment due to convenient systemic treatment with activating ligand.
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Affiliation(s)
- Charles D Nichols
- Department of Pharmacology and Therapeutics, Louisiana State University Health Sciences Center New Orleans, LA, USA
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Tönjes A, Koriath M, Schleinitz D, Dietrich K, Böttcher Y, Rayner NW, Almgren P, Enigk B, Richter O, Rohm S, Fischer-Rosinsky A, Pfeiffer A, Hoffmann K, Krohn K, Aust G, Spranger J, Groop L, Blüher M, Kovacs P, Stumvoll M. Genetic variation in GPR133 is associated with height: genome wide association study in the self-contained population of Sorbs. Hum Mol Genet 2009; 18:4662-8. [PMID: 19729412 DOI: 10.1093/hmg/ddp423] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Recently, associations of several common genetic variants with height have been reported in different populations. We attempted to identify further variants associated with adult height in a self-contained population (the Sorbs in Eastern Germany) as discovery set. We performed a genome wide association study (GWAS) (approximately 390,000 genetic polymorphisms, Affymetrix gene arrays) on adult height in 929 Sorbian individuals. Subsequently, the best SNPs (P < 0.001) were taken forward to a meta-analysis together with two independent cohorts [Diabetes Genetics Initiative, British 1958 Birth Cohort, (58BC, publicly available)]. Furthermore, we genotyped our best signal for replication in two additional German cohorts (Leipzig, n = 1044 and Berlin, n = 1728). In the primary Sorbian GWAS, we identified 5 loci with a P-value < 10(-5) and 455 SNPs with P-value < 0.001. In the meta-analysis on those 455 SNPs, only two variants in GPR133 (rs1569019 and rs1976930; in LD with each other) retained a P-value at or below 10(-6) and were associated with height in the three cohorts individually. Upon replication, the SNP rs1569019 showed significant effects on height in the Leipzig cohort (P = 0.004, beta = 1.166) and in 577 men of the Berlin cohort (P = 0.049, beta = 1.127) though not in women. The combined analysis of all five cohorts (n = 6,687) resulted in a P-value of 4.7 x 10(-8) (beta = 0.949). In conclusion, our GWAS suggests novel loci influencing height. In view of the robust replication in five different cohorts, we propose GPR133 to be a novel gene associated with adult height.
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Affiliation(s)
- Anke Tönjes
- Department of Medicine, University of Leipzig, Leipzig,Germany
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Alexander GM, Rogan SC, Abbas AI, Armbruster BN, Pei Y, Allen JA, Nonneman RJ, Hartmann J, Moy SS, Nicolelis MA, McNamara JO, Roth BL. Remote control of neuronal activity in transgenic mice expressing evolved G protein-coupled receptors. Neuron 2009; 63:27-39. [PMID: 19607790 DOI: 10.1016/j.neuron.2009.06.014] [Citation(s) in RCA: 694] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 05/13/2009] [Accepted: 06/12/2009] [Indexed: 12/22/2022]
Abstract
Examining the behavioral consequences of selective CNS neuronal activation is a powerful tool for elucidating mammalian brain function in health and disease. Newly developed genetic, pharmacological, and optical tools allow activation of neurons with exquisite spatiotemporal resolution; however, the inaccessibility to light of widely distributed neuronal populations and the invasiveness required for activation by light or infused ligands limit the utility of these methods. To overcome these barriers, we created transgenic mice expressing an evolved G protein-coupled receptor (hM3Dq) selectively activated by the pharmacologically inert, orally bioavailable drug clozapine-N-oxide (CNO). Here, we expressed hM3Dq in forebrain principal neurons. Local field potential and single-neuron recordings revealed that peripheral administration of CNO activated hippocampal neurons selectively in hM3Dq-expressing mice. Behavioral correlates of neuronal activation included increased locomotion, stereotypy, and limbic seizures. These results demonstrate a powerful chemical-genetic tool for remotely controlling the activity of discrete populations of neurons in vivo.
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Shockley KR, Lazarenko OP, Czernik PJ, Rosen CJ, Churchill GA, Lecka-Czernik B. PPARgamma2 nuclear receptor controls multiple regulatory pathways of osteoblast differentiation from marrow mesenchymal stem cells. J Cell Biochem 2009; 106:232-46. [PMID: 19115254 DOI: 10.1002/jcb.21994] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Rosiglitazone (Rosi), a member of the thiazolidinedione class of drugs used to treat type 2 diabetes, activates the adipocyte-specific transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma). This activation causes bone loss in animals and humans, at least in part due to suppression of osteoblast differentiation from marrow mesenchymal stem cells (MSC). In order to identify mechanisms by which PPARgamma2 suppresses osteoblastogenesis and promotes adipogenesis in MSC, we have analyzed the PPARgamma2 transcriptome in response to Rosi. A total of 4,252 transcriptional changes resulted when Rosi (1 microM) was applied to the U-33 marrow stromal cell line stably transfected with PPARgamma2 (U-33/gamma2) as compared to non-induced U-33/gamma2 cells. Differences between U-33/gamma2 and U-33 cells stably transfected with empty vector (U-33/c) comprised 7,928 transcriptional changes, independent of Rosi. Cell type-, time- and treatment-specific gene clustering uncovered distinct patterns of PPARgamma2 transcriptional control of MSC lineage commitment. The earliest changes accompanying Rosi activation of PPARgamma2 included effects on Wnt, TGFbeta/BMP and G-protein signaling activities, as well as sustained induction of adipocyte-specific gene expression and lipid metabolism. While suppression of osteoblast phenotype is initiated by a diminished expression of osteoblast-specific signaling pathways, induction of the adipocyte phenotype is initiated by adipocyte-specific transcriptional regulators. This indicates that distinct mechanisms govern the repression of osteogenesis and the stimulation of adipogenesis. The co-expression patterns found here indicate that PPARgamma2 has a dominant role in controlling osteoblast differentiation and suggests numerous gene-gene interactions that could lead to the identification of a "master" regulatory scheme directing this process.
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Affiliation(s)
- Keith R Shockley
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, USA
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Pei Y, Rogan SC, Yan F, Roth BL. Engineered GPCRs as tools to modulate signal transduction. Physiology (Bethesda) 2009; 23:313-21. [PMID: 19074739 DOI: 10.1152/physiol.00025.2008] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Different families of G-protein-coupled receptors (GPCRs) have been engineered to provide exclusive control over the activation of these receptors and thus to understand better the consequences of their signaling in vitro and in vivo. These engineered receptors, named RASSLs (receptors activated solely by synthetic ligands) and DREADDs (designer receptors exclusively activated by designer drugs), are insensitive to their endogenous ligands but can be activated by synthetic drug-like compounds. Currently, the existing RASSLs and DREADDs cover the Gi, Gq, and Gs signaling pathways. These modified GPCRs can be utilized as ideal tools to study GPCR functions selectively in specific cellular populations.
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Affiliation(s)
- Ying Pei
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, USA
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Wang X, Yuan L, Huang J, Zhang TL, Wang K. Lanthanum enhances in vitro osteoblast differentiation via pertussis toxin-sensitive gi protein and ERK signaling pathway. J Cell Biochem 2008; 105:1307-15. [DOI: 10.1002/jcb.21932] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Conklin BR, Hsiao EC, Claeysen S, Dumuis A, Srinivasan S, Forsayeth JR, Guettier JM, Chang WC, Pei Y, McCarthy KD, Nissenson RA, Wess J, Bockaert J, Roth BL. Engineering GPCR signaling pathways with RASSLs. Nat Methods 2008; 5:673-8. [PMID: 18668035 DOI: 10.1038/nmeth.1232] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We are creating families of designer G protein-coupled receptors (GPCRs) to allow for precise spatiotemporal control of GPCR signaling in vivo. These engineered GPCRs, called receptors activated solely by synthetic ligands (RASSLs), are unresponsive to endogenous ligands but can be activated by nanomolar concentrations of pharmacologically inert, drug-like small molecules. Currently, RASSLs exist for the three major GPCR signaling pathways (G(s), G(i) and G(q)). We review these advances here to facilitate the use of these powerful and diverse tools.
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Affiliation(s)
- Bruce R Conklin
- Gladstone Institute of Cardiovascular Disease, 1650 Owens Street, San Francisco, California 94158, USA.
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Osteoblast expression of an engineered Gs-coupled receptor dramatically increases bone mass. Proc Natl Acad Sci U S A 2008; 105:1209-14. [PMID: 18212126 DOI: 10.1073/pnas.0707457105] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Osteoblasts are essential for maintaining bone mass, avoiding osteoporosis, and repairing injured bone. Activation of osteoblast G protein-coupled receptors (GPCRs), such as the parathyroid hormone receptor, can increase bone mass; however, the anabolic mechanisms are poorly understood. Here we use "Rs1," an engineered GPCR with constitutive G(s) signaling, to evaluate the temporal and skeletal effects of G(s) signaling in murine osteoblasts. In vivo, Rs1 expression induces a dramatic anabolic skeletal response, with midfemur girth increasing 1,200% and femur mass increasing 380% in 9-week-old mice. Bone volume, cellularity, areal bone mineral density, osteoblast gene markers, and serum bone turnover markers were also elevated. No such phenotype developed when Rs1 was expressed after the first 4 weeks of postnatal life, indicating an exquisite temporal sensitivity of osteoblasts to Rs1 expression. This pathway may represent an important determinant of bone mass and may open future avenues for enhancing bone repair and treating metabolic bone diseases.
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