Osteoblast expression of an engineered G
            <sub>s</sub>
            -coupled receptor dramatically increases bone mass

Hsiao, Edward C.; Boudignon, Benjamin; Chang, Wei Chun; Bencsik, Margaret; Peng, Jeffrey; Nguyen, Trieu; Manalac, Carlota; Halloran, Bernard P.; Conklin, Bruce R.; Nissenson, Robert A.

doi:10.1073/pnas.0707457105

Cited by 99 publications

(162 citation statements)

References 49 publications

(48 reference statements)

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“…Prior studies showed no sexual dimorphism in the bone phenotype, including differences in body length or weight. (9,14,15) All animals in this study were maintained on the FVB/N background and fed a diet containing 200 mg/kg of doxycycline (DoxDiet; Bio-Serv, Frenchtown, NJ, USA) to suppress transgene activity. (14)(15)(16) Delayed expression of Rs1 was activated by switching the mice to regular mouse chow at 4 weeks of age.…”

Section: Animalsmentioning

confidence: 99%

“…(14)(15)(16) Delayed expression of Rs1 was activated by switching the mice to regular mouse chow at 4 weeks of age. (15) The Col1/Rs1-late mice do not develop the dramatic increase in trabecular bone during the first 30 weeks of life, (9) yet have detectable Rs1 expression and can show dramatic bone formation with ligand-mediated G s activation. (31) The Col1/Rs1-late mice were subjected to tibia fracture at age 14 to 16 weeks.…”

Section: Animalsmentioning

confidence: 99%

“…(20) Histological, immunohistochemistry, and quantitative PCR assessments of the callus tissue were performed as described. (9,10,22) (Details are available in the Supporting Information-Methods and Supporting Tables 1 and 2. )…”

Section: Analysis Of Fracture Callus Formationmentioning

confidence: 99%

“…(7,8) The G s and G i pathways may have independent functions in osteoblasts despite their common convergence on the cAMP second messenger. (9,10) There has been growing interest in molecular crosstalk between different GPCRs as a way to increase the dynamic complexity of cell signaling (11,12) ; however, this crosstalk also makes it difficult to assess how individual pathways control cellular function. Dissecting the functions of GPCRs in osteoblasts in bone healing is further limited by several significant challenges, including the diversity of GPCRs and their ligands, the large number of orphan GPCRs, the complexity of the GNAS locus that encodes G s a, (13) and redundancy of the multiple G i a subunits.…”

Section: Introductionmentioning

confidence: 99%

“…(9) RASSLs no longer respond to endogenous hormones but can be activated by synthetic small-molecule ligands and have proved to be useful for regulating and studying G-protein signaling in several complex systems, including bone. (9,14,15) We further showed that delaying Rs1 expression in Col1(2.3) þ /Rs1 þ until after 4 weeks of age (referred to as Col1/Rs1-late mice herein) significantly attenuates the bone formation phenotype. (15) However, bone formation can be stimulated in these Col1(2.3) þ /Rs1 þ mice by treatment with RS67333, a synthetic serotonin receptor agonist that strongly activates the Rs1 receptor and further increases G s signaling.…”

Section: Introductionmentioning

confidence: 99%

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Loss of Gi G-Protein-Coupled Receptor Signaling in Osteoblasts Accelerates Bone Fracture Healing

Wang

Hsiao

Lieu

et al. 2015

Journal of Bone and Mineral Research

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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 agerelated 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 G s 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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Section: Animalsmentioning

confidence: 99%

Section: Animalsmentioning

confidence: 99%

Section: Analysis Of Fracture Callus Formationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Loss of Gi G-Protein-Coupled Receptor Signaling in Osteoblasts Accelerates Bone Fracture Healing

Wang

Hsiao

Lieu

et al. 2015

Journal of Bone and Mineral Research

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Lysophosphatidic Acid (LPA) Signaling and Bone

Salles

Laurencin‐Dalicieux

Conte-Auriol

et al. 2013

Lysophospholipid Receptors

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Increased Osteoblast Gα_S Promotes Ossification by Suppressing Cartilage and Enhancing Callus Mineralization During Fracture Repair in Mice

Lee,

Changoor,

Grynpas

et al. 2023

JBMR Plus

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GαS, the stimulatory G protein α‐subunit that raises intracellular cAMP levels by activating adenylyl cyclase, plays a vital role in bone development, maintenance, and remodeling. Previously, using transgenic mice overexpressing GαS in osteoblasts (GS‐Tg), we demonstrated the influence of osteoblast GαS level on osteogenesis, bone turnover, and skeletal responses to hyperparathyroidism. To further investigate whether alterations in GαS levels affect endochondral bone repair, a postnatal bone regenerative process that recapitulates embryonic bone development, we performed stabilized tibial osteotomy in male GS‐Tg mice at 8 weeks of age and examined the progression of fracture healing by micro‐CT, histomorphometry, and gene expression analysis over a 4‐week period. Bone fractures from GS‐Tg mice exhibited diminished cartilage formation at the time of peak soft callus formation at 1 week post‐fracture followed by significantly enhanced callus mineralization and new bone formation at 2 weeks post‐fracture. The opposing effects on chondrogenesis and osteogenesis were validated by downregulation of chondrogenic markers and upregulation of osteogenic markers. Histomorphometric analysis at times of increased bone formation (2 and 3 weeks post‐fracture) revealed excess fibroblast‐like cells on newly formed woven bone surfaces and elevated osteocyte density in GS‐Tg fractures. Coincident with enhanced callus mineralization and bone formation, GS‐Tg mice showed elevated active β‐catenin and Wntless proteins in osteoblasts at 2 weeks post‐fracture, further substantiated by increased mRNA encoding various canonical Wnts and Wnt target genes, suggesting elevated osteoblastic Wnt secretion and Wnt/β‐catenin signaling. The GS‐Tg bony callus at 4 weeks post‐fracture exhibited greater mineral density and decreased polar moment of inertia, resulting in improved material stiffness. These findings highlight that elevated GαS levels increase Wnt signaling, conferring an increased osteogenic differentiation potential at the expense of chondrogenic differentiation, resulting in improved mechanical integrity. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

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Osteoblast expression of an engineered G _s -coupled receptor dramatically increases bone mass

Cited by 99 publications

References 49 publications

Loss of Gi G-Protein-Coupled Receptor Signaling in Osteoblasts Accelerates Bone Fracture Healing

Loss of Gi G-Protein-Coupled Receptor Signaling in Osteoblasts Accelerates Bone Fracture Healing

Lysophosphatidic Acid (LPA) Signaling and Bone

Increased Osteoblast Gα_S Promotes Ossification by Suppressing Cartilage and Enhancing Callus Mineralization During Fracture Repair in Mice

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Osteoblast expression of an engineered G s -coupled receptor dramatically increases bone mass

Cited by 99 publications

References 49 publications

Loss of Gi G-Protein-Coupled Receptor Signaling in Osteoblasts Accelerates Bone Fracture Healing

Loss of Gi G-Protein-Coupled Receptor Signaling in Osteoblasts Accelerates Bone Fracture Healing

Lysophosphatidic Acid (LPA) Signaling and Bone

Increased Osteoblast GαS Promotes Ossification by Suppressing Cartilage and Enhancing Callus Mineralization During Fracture Repair in Mice

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Product

Resources

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Osteoblast expression of an engineered G _s -coupled receptor dramatically increases bone mass

Increased Osteoblast Gα_S Promotes Ossification by Suppressing Cartilage and Enhancing Callus Mineralization During Fracture Repair in Mice