Targeted overexpression of G protein-coupled receptor kinase-2 in osteoblasts promotes bone loss

2005 ◽  
Vol 288 (4) ◽  
pp. E826-E834 ◽  
Author(s):  
Liming Wang ◽  
Shiguang Liu ◽  
L. Darryl Quarles ◽  
Robert F. Spurney
Keyword(s):  
Bone Formation ◽  
Trabecular Bone ◽  
Bone Remodeling ◽  
G Protein ◽  
Mrna Levels ◽  
G Protein Coupled Receptor ◽  
Mineral Density ◽  
Trabecular Thickness ◽  
Osteoclastic Activity ◽  
G Protein Coupled

To investigate the role of G protein-coupled receptor kinases (GRKs) in regulating bone formation in vivo, we overexpressed the potent G protein-coupled receptor (GPCR) regulator GRK2 in osteoblasts, using the osteocalcin gene-2 promoter to target expression to osteoblastic cells. Using the parathyroid hormone (PTH) receptor as a model system, we found that overexpression of GRK2 in osteoblasts attenuated PTH-induced cAMP generation by mouse calvaria ex vivo. This decrease in GPCR responsiveness was associated with a reduction in bone mineral density (BMD) in transgenic (TG) mice compared with non-TG littermate controls. The decrease in BMD was most prominent in trabecular-rich lumbar spine and was not observed in cortical bone of the femoral shaft. Quantitative computed tomography indicated that the loss of trabecular bone was due to a decrease in trabecular thickness, with little change in trabecular number. Histomorphometric analyses confirmed the decrease in trabecular bone volume and demonstrated reduced bone remodeling, as evidenced by a decrease in osteoblast numbers and osteoblast-mediated bone formation. Osteoclastic activity also appeared to be reduced because urinary excretion of the osteoclastic activity marker deoxypyridinoline was decreased in TG mice compared with control animals. Consistent with reduced coupling of osteoblast-mediated bone formation to osteoclastic bone resorption, mRNA levels of both osteoprotegrin and receptor activator of NF-κB ligand were altered in calvaria of TG mice in a pattern that would promote a low rate of bone remodeling. Taken together, these data suggest that enhancing GRK2 activity and consequently reducing GPCR activity in osteoblasts produces a low bone-turnover state that reduces bone mass.

scholarly journals Ligand-Mediated Activation of an Engineered Gs G Protein-Coupled Receptor in Osteoblasts Increases Trabecular Bone Formation

2010 ◽  
Vol 24 (3) ◽  
pp. 621-631 ◽  
Author(s):  
Edward C. Hsiao ◽  
Susan M. Millard ◽  
Alyssa Louie ◽  
Yong Huang ◽  
Bruce R. Conklin ◽  
...  
Keyword(s):  
Bone Formation ◽  
Trabecular Bone ◽  
G Protein ◽  
Bone Growth ◽  
G Protein Coupled Receptor ◽  
Gpcr Signaling ◽  
Adult Mice ◽  
Age Dependent ◽  
Synthetic Ligand ◽  
G Protein Coupled

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 Gs 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 Gs-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 Gs 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 Gs-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 Gs signaling than osteoblasts at the bone diaphysis. This model provides a powerful tool for investigating the effects of ligand-activated Gs-GPCR signaling on dynamic bone growth and remodeling.

scholarly journals A role for G protein-coupled receptor 137b in bone remodeling in mouse and zebrafish

Bone ◽  
2019 ◽  
Vol 127 ◽  
pp. 104-113
Author(s):  
K. Urso ◽  
J. Caetano-Lopes ◽  
P.Y. Lee ◽  
J. Yan ◽  
K. Henke ◽  
...  
Keyword(s):  
Bone Remodeling ◽  
G Protein ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

scholarly journals G Protein-Coupled Receptor 30 Expression Is Required for Estrogen Stimulation of Primordial Follicle Formation in the Hamster Ovary

Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4452-4461 ◽  
Author(s):  
Cheng Wang ◽  
Eric R. Prossnitz ◽  
Shyamal K. Roy
Keyword(s):  
G Protein ◽  
Fluorescein Isothiocyanate ◽  
Primordial Follicle ◽  
Mrna Levels ◽  
G Protein Coupled Receptor ◽  
Ovary Cells ◽  
Primordial Follicles ◽  
Protein Levels ◽  
G Protein Coupled

Estradiol-17β (E2) plays an important role in the formation and development of primordial follicles, but the mechanisms remain unclear. G protein-coupled receptor 30 (GPR30) can mediate a rapid and transcription-independent E2 signaling in various cells. The objectives of this study were to examine whether GPR30 was expressed in the neonatal hamster ovary and whether it could mediate estrogen action during the formation of primordial follicles. GPR30 mRNA levels decreased from the 13th day of gestation (E13) through the second day of postnatal (P2) life, followed by steady increases from P3 through P6. Consistent with the changes in mRNA levels, GPR30 protein expression decreased from E13 to P2 followed by a significant increase by P7, the day before the first appearance of primordial follicles in the hamster ovary. GPR30 was expressed both in the oocytes and somatic cells, although the expression in the oocytes was low. GPR30 protein was located primarily in the perinuclear endoplasmic reticulum, which was also the site of E2-BSA-FITC (E2-BSA-fluorescein isothiocyanate) binding. E2 or E2-BSA increased intracellular calcium in neonatal hamster ovary cells in vitro. Exposure to GPR30 small interfering RNA in vitro significantly reduced GPR30 mRNA and protein levels in cultured hamster ovaries, attenuated E-BSA binding to cultured P6 ovarian cells, and markedly suppressed estrogen-stimulated primordial follicle formation. These results suggest that a membrane estrogen receptor, GPR30, is expressed in the ovary during perinatal development and mediates E2 action on primordial follicle formation.

Effect of Minocycline on Osteoporosis

1998 ◽  
Vol 12 (1) ◽  
pp. 71-75 ◽  
Author(s):  
S. Williams ◽  
A. Wakisaka ◽  
Q.Q. Zeng ◽  
J. Barnes ◽  
S. Seyedin ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Trabecular Bone ◽  
Formation Rate ◽  
Inhibitory Effect ◽  
Mineral Apposition Rate ◽  
Mineral Density ◽  
Bone Formation Rate ◽  
Trabecular Thickness ◽  
Trabecular Bone Area

The effect of oral minocycline on osteopenia in ovariectomized (OVX) old rats was examined in this study. Rats were divided into 4 groups: sham-operated, OVX followed by treatment with vehicle, minocycline, or 17β-estradiol. The treatment was initiated one day after OVX and proceeded for 8 wks. OVX reduced bone mineral density (BMD) in the whole femur and in the femoral regions that are enriched in trabecular bone. Treatment with minocycline or estrogen prevented a decrease in BMD. Femoral trabecular bone area, trabecular number, and trabecular thickness were reduced, and trabecular separation was increased by OVX. Treatment with minocycline or estrogen abolished the detrimental effects induced by OVX. OVX also reduced indices that reflect the interconnectivity of trabecular bone, and the loss of trabecular connectivity was prevented by treatment with minocycline or estrogen. Based on the levels of urinary pyridinoline, we showed that the effect of estrogen, but not minocycline, was primarily through its inhibitory effect on bone resorption. Analysis of bone turnover activity suggests that OVX increased parameters associated with bone resorption (eroded surface) and formation (osteoid surface, mineralizing surface, mineral apposition rate, and bone formation rate). Treatment with minocycline reduced bone resorption modestly and stimulated bone formation substantially. In contrast, treatment with estrogen drastically reduced parameters associated with both bone resorption and formation. We have concluded that oral minocycline can effectively prevent the decrease in BMD and trabecular bone through its dual effects on bone resorption and formation.

scholarly journals Association of β-arrestin1 and p53-MDM2 signaling in the development of missed abortion

2020 ◽  
Author(s):  
Ting Liu ◽  
Yuyan Ma ◽  
Qihui Yin ◽  
Huanyu Zhou ◽  
Yan Fang
Keyword(s):  
G Protein ◽  
Cell Invasion ◽  
Positive Staining ◽  
Mrna Levels ◽  
Healthy Controls ◽  
G Protein Coupled Receptor ◽  
Missed Abortion ◽  
Real Time Quantitative Pcr ◽  
Elevated Expression ◽  
G Protein Coupled

Abstract BackgroundMissed abortion is a nonviable pregnancy before the 20th week of gestation with retained products of conception. The definite etiology and pathogenesis are not fully understood. β-arrestin1, the important dynamic multitask scaffold protein, it play an important regulatory role in interacting with G protein-coupled receptor (GPCR) to mediate its homologous desensitization and internalization. Recent studies have demonstrated that p53/Mdm2-mediated ubiquitination of the IGF-1R maybe closely related to G protein-coupled receptor kinases (GRK)/β-arrestin1 system. Our previous studies have confirmed that the elevated expression of p53 and Mdm2 may be responsible for apoptosis during missed abortion. However, there was no information surrounding β-arrestin1 in missed abortion.MethodsThe mRNA levels of β-arrestin1 in villous samples of 31 missed abortion patients and 31 healthy controls were determined by real-time quantitative PCR. Immunohistochemistry was used to explore the expression and location of β-arrestin1, p53, Mdm2, VEGF, HIF-lα in trophoblasts. We up-regulated and silenced the expression of β-arrestin1 by lentiviral transfection, transwell assays were performed to examine the influences of β-arrestin1 expression on cell invasion. Furthermore, we explored the expression of several important proteins which may be related to β-arrestin1.Resultsβ-arrestin1 mRNA levels in the villous samples from women with missed abortion were found to be dramatically lower than in women who had normal pregnancies. The immunohistochemistry results showed that β-arrestin1 positive staining was significantly lower in missed abortion group than that in normal pregnancies group. Furthermore, the patients with missed abortion showed significantly higher levels of p53, Mdm2 and HIF-lα, lower level of VEGF than healthy controls by immunohistochemistry. The protein expressions of p-ERK、p-AKT、p-p53 in HRT-8 cells were significantly downregulated by reducing β-arrestin1 expression, while the expression of p-NF-ΚB、p-Mdm2 were enhanced. Overexpression of β-arrestin1 exhibited the adverse effect. The loss expression of β-arrestin1 expression was significantly related with decreased cell invasion ability.ConclusionOur data indicated that β-arrestin1 could play an important role in maintaining the maternal-fetal tolerance, the decreased β-arrestin1 expression in the villous samples may be related to the development of missed abortion.

scholarly journals Regulation of bone formation and remodeling by G-protein-coupled receptor 48

Development ◽  
2009 ◽  
Vol 136 (16) ◽  
pp. 2747-2756 ◽  
Author(s):  
J. Luo ◽  
W. Zhou ◽  
X. Zhou ◽  
D. Li ◽  
J. Weng ◽  
...  
Keyword(s):  
Bone Formation ◽  
G Protein ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

scholarly journals Elevated Serum 25-Hydroxyvitamin D Levels Are Associated with Improved Bone Formation and Micro-Structural Measures in Elderly Hip Fracture Patients

2019 ◽  
Vol 8 (11) ◽  
pp. 1988 ◽  
Author(s):  
Deepti Sharma ◽  
Rebecca Sawyer ◽  
Thomas Robertson ◽  
Roumen Stamenkov ◽  
Lucian Solomon ◽  
...  
Keyword(s):  
Vitamin D ◽  
Bone Formation ◽  
Trabecular Bone ◽  
Elevated Serum ◽  
Bone Volume ◽  
Royal Adelaide Hospital ◽  
Mrna Levels ◽  
Vitamin D Status ◽  
Mineral Density ◽  
Bone Biopsies

Vitamin D, along with calcium, is generally considered necessary for bone health and reduction of fractures. However, he effects of improving vitamin D status have not always been observed to improve bone mineral density (BMD). We have investigated whether varying vitamin D status in humans, as measured by serum 25(OH)D levels, relate to micro-structural and histomorphetric measures of bone quality and quantity, rather than density. Intertrochanteric trabecular bone biopsies and serum samples were collected from patients undergoing hip arthroplasty (65 females, 38 males, mean age 84.8 ± 8.3 years) at Royal Adelaide Hospital. Estimated GFR, serum ionized calcium, alkaline phosphatase, albumin, supplement and medication intake prior to surgery were taken from patient case records. Serum 25(OH)D, 1,25(OH)2D, and parathyroid hormone (PTH) levels were measured by immunoassays. Trabecular bone structural indices were determined by high-resolution micro-CT. Mean wall thickness (MWT) was measured on toluidine blue-stained histological sections. Bone mRNA levels for vitamin D metabolising enzymes CYP27B1 and CYP24A1 were measured by qRT-PCR. While serum 25(OH)D levels did not associate with bone volume/tissue volume (BV/TV%), serum 25(OH)D levels were strongly and independently associated with MWT (r = 0.81 p < 0.0001) with values significantly greater in patients with higher serum 25(OH)D levels. Furthermore, serum 25(OH)D levels were negatively associated with Bone Surface/Bone Volume (BS/BV) (r = −0.206, p < 0.05) and together with bone CYP27B1 and CYP24A1 mRNA accounted for 10% of the variability of BS/BV (p = 0.001). These data demonstrate that serum 25(OH)D is an independent positive predictor of micro-structural and bone formation measures and may be dependent, in part, on its metabolism within the bone.

scholarly journals The G-Protein-Coupled Receptor GPR103 Regulates Bone Formation

2006 ◽  
Vol 26 (2) ◽  
pp. 709-717 ◽  
Author(s):  
Helene Baribault ◽  
Jean Danao ◽  
Jamila Gupte ◽  
Li Yang ◽  
Banghua Sun ◽  
...  
Keyword(s):  
Bone Formation ◽  
G Protein ◽  
Primary Cultures ◽  
Whole Body ◽  
Pcr Analysis ◽  
G Protein Coupled Receptor ◽  
Reverse Transcription Pcr ◽  
Natural Ligand ◽  
Knockout Animals ◽  
G Protein Coupled

ABSTRACT GPR103 is a G-protein-coupled receptor with reported expression in brain, heart, kidney, adrenal gland, retina, and testis. It encodes a 455-amino-acid protein homologous to neuropeptide FF2, neuropeptide Y2, and galanin GalR1 receptors. Its natural ligand was recently identified as 26RFa, a novel human RF-amide-related peptide with orexigenic activity. To identify the function of GPR103, we generated GPR103-deficient mice. Homozygous mutant mice were viable and fertile. Their body weight was undistinguishable from that of their wild-type littermates. Histological analysis revealed that GPR103−/− mice exhibited a thinned osteochondral growth plate, a thickening of trabecular branches, and a reduction in osteoclast number, suggestive of an early arrest of osteochondral bone formation. Microcomputed tomography confirmed the reduction in trabecular bone and connective tissue densities in GPR103 knockout animals. Whole-body radiography followed by morphometric analysis revealed a kyphosis in mutant animals. Reverse transcription-PCR analysis showed that GPR103 was expressed in human skull, mouse spine, and several osteoblast cell lines. Dexamethasone, a known inhibitor of osteoblast growth and inducer of osteoblast differentiation, inhibited GPR103 expression in human osteoblast primary cultures. Altogether, these results suggest that osteopenia in GPR103−/− mice may be mediated directly by the loss of GPR103 expression in bone.

Running exercise alleviates trabecular bone loss and osteopenia in hemizygous β-globin knockout thalassemic mice

2014 ◽  
Vol 306 (12) ◽  
pp. E1406-E1417 ◽  
Author(s):  
Kanogwun Thongchote ◽  
Saovaros Svasti ◽  
Jarinthorn Teerapornpuntakit ◽  
Nateetip Krishnamra ◽  
Narattaphol Charoenphandhu
Keyword(s):  
Bone Resorption ◽  
Bone Loss ◽  
Bone Formation ◽  
Trabecular Bone ◽  
Elevated Serum ◽  
Bone Volume ◽  
Trabecular Bone Volume ◽  
Mineral Density ◽  
Trabecular Thickness ◽  
Running Exercise

A marked decrease in β-globin production led to β-thalassemia, a hereditary anemic disease associated with bone marrow expansion, bone erosion, and osteoporosis. Herein, we aimed to investigate changes in bone mineral density (BMD) and trabecular microstructure in hemizygous β-globin knockout thalassemic (BKO) mice and to determine whether endurance running (60 min/day, 5 days/wk for 12 wk in running wheels) could effectively alleviate bone loss in BKO mice. Both male and female BKO mice (1–2 mo old) showed growth retardation as indicated by smaller body weight and femoral length than their wild-type littermates. A decrease in BMD was more severe in female than in male BKO mice. Bone histomorphometry revealed that BKO mice had decreases in trabecular bone volume, trabecular number, and trabecular thickness, presumably due to suppression of osteoblast-mediated bone formation and activation of osteoclast-mediated bone resorption, the latter of which was consistent with elevated serum levels of osteoclastogenic cytokines IL-1α and -1β. As determined by peripheral quantitative computed tomography, running increased cortical density and thickness in the femoral and tibial diaphyses of BKO mice compared with those of sedentary BKO mice. Several histomorphometric parameters suggested an enhancement of bone formation (e.g., increased mineral apposition rate) and suppression of bone resorption (e.g., decreased osteoclast surface), which led to increases in trabecular bone volume and trabecular thickness in running BKO mice. In conclusion, BKO mice exhibited pervasive osteopenia and impaired bone microstructure, whereas running exercise appeared to be an effective intervention in alleviating bone microstructural defect in β-thalassemia.

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