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Rizzoli R, Adachi JD, Cooper C, Dere W, Devogelaer JP, Diez-Perez A, Kanis JA, Laslop A, Mitlak B, Papapoulos S, Ralston S, Reiter S, Werhya G, Reginster JY. Management of glucocorticoid-induced osteoporosis. Calcif Tissue Int 2012; 91:225-43. [PMID: 22878667 DOI: 10.1007/s00223-012-9630-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 05/29/2012] [Indexed: 01/05/2023]
Abstract
This review summarizes the available evidence-based data that form the basis for therapeutic intervention and covers the current status of glucocorticoid-induced osteoporosis (GIOP) management, regulatory requirements, and risk-assessment options. Glucocorticoids are known to cause bone loss and fractures, yet many patients receiving or initiating glucocorticoid therapy are not appropriately evaluated and treated. An European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis workshop was convened to discuss GIOP management and to provide a report by a panel of experts. An expert panel reviewed the available studies that discussed approved therapeutic agents, focusing on randomized and controlled clinical trials reporting on bone mineral density and/or fracture risk of at least 48 weeks' duration. There is no evidence that GIOP and postmenopausal osteoporosis respond differently to treatments. The FRAX algorithm can be adjusted according to glucocorticoid dose. Available antiosteoporotic therapies such as bisphosphonates and teriparatide are efficacious in GIOP management. Several other agents approved for the treatment of postmenopausal osteoporosis may become available for GIOP. It is advised to stop antiosteoporotic treatment after glucocorticoid cessation, unless the patient remains at increased risk of fracture. Calcium and vitamin D supplementation as an osteoporosis-prevention measure is less effective than specific antiosteoporotic treatment. Fracture end-point studies and additional studies investigating specific subpopulations (pediatric, premenopausal, or elderly patients) would strengthen the evidence base and facilitate the development of intervention thresholds and treatment guidelines.
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Affiliation(s)
- R Rizzoli
- Service of Bone Diseases, Geneva University Hospitals, Geneva, Switzerland.
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2
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Capelo LP, Beber EH, Huang SA, Zorn TM, Bianco AC, Gouveia CH. Deiodinase-mediated thyroid hormone inactivation minimizes thyroid hormone signaling in the early development of fetal skeleton. Bone 2008; 43:921-30. [PMID: 18682303 PMCID: PMC4683160 DOI: 10.1016/j.bone.2008.06.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 06/24/2008] [Accepted: 06/28/2008] [Indexed: 10/21/2022]
Abstract
Thyroid hormone (TH) plays a key role on post-natal bone development and metabolism, while its relevance during fetal bone development is uncertain. To study this, pregnant mice were made hypothyroid and fetuses harvested at embryonic days (E) 12.5, 14.5, 16.5 and 18.5. Despite a marked reduction in fetal tissue concentration of both T4 and T3, bone development, as assessed at the distal epiphyseal growth plate of the femur and vertebra, was largely preserved up to E16.5. Only at E18.5, the hypothyroid fetuses exhibited a reduction in femoral type I and type X collagen and osteocalcin mRNA levels, in the length and area of the proliferative and hypertrophic zones, in the number of chondrocytes per proliferative column, and in the number of hypertrophic chondrocytes, in addition to a slight delay in endochondral and intramembranous ossification. This suggests that up to E16.5, thyroid hormone signaling in bone is kept to a minimum. In fact, measuring the expression level of the activating and inactivating iodothyronine deiodinases (D2 and D3) helped understand how this is achieved. D3 mRNA was readily detected as early as E14.5 and its expression decreased markedly ( approximately 10-fold) at E18.5, and even more at 14 days after birth (P14). In contrast, D2 mRNA expression increased significantly by E18.5 and markedly ( approximately 2.5-fold) by P14. The reciprocal expression levels of D2 and D3 genes during early bone development along with the absence of a hypothyroidism-induced bone phenotype at this time suggest that coordinated reciprocal deiodinase expression keeps thyroid hormone signaling in bone to very low levels at this early stage of bone development.
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Affiliation(s)
- Luciane P. Capelo
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000, Brazil
| | - Eduardo H. Beber
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000, Brazil
| | - Stephen A. Huang
- Division of Endocrinology, Children’s Hospital Boston, Boston, Massachusetts 02115, USA
| | - Telma M.T. Zorn
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000, Brazil
| | - Antonio C. Bianco
- Thyroid Section, Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Cecília H.A. Gouveia
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000, Brazil
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-000, Brazil
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3
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Abstract
UNLABELLED Osteoporosis and fractures are frequent and important consequences of glucocorticoid therapy. Many factors contribute to bone loss during glucocorticoid therapy, such as underlying disease, malnutrition, vitamin D insufficiency, hypogonadism, and low body weight. Bone loss occurs particularly in the first few months of glucocorticoid treatment and affects more cancellous than cortical bone, with reduced bone formation and increased bone resorption. The risk of fracture increases rapidly in patients with glucocorticoid therapy. The existence of a threshold is not well defined but the risk of fracture is increased in patients with higher doses of glucocorticoids. Other effects include altered production of gonadal sex hormones, inhibition of intestinal calcium absorption, and enhancement of renal excretion of calcium. Prevention of glucocorticoid-induced osteoporosis is based on general measures such as calcium and vitamin D supplementation, adequate protein intake, regular physical exercise, and specific therapies. Bisphosphonates, which are potent bone resorption inhibitors, have been shown to increase bone mineral density and to decrease fracture risk, so that they represent the first choice in the prevention of glucocorticoid-induced osteoporosis. Glucocorticoid-induced osteoporosis is a major burden to those whom it affects. It can be prevented provided efficacious preventive measures are introduced early during glucocorticoid treatment. LEVEL OF EVIDENCE Level V (expert opinion). See the Guidelines for Authors for a complete description of the levels of evidence.
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Affiliation(s)
- Pietra Pennisi
- Service of Bone Diseases, WHO Collaborating Center for Osteoporosis Prevention, Department of Rehabilitation and Geriatrics, University Hospital of Geneva, Geneva, Switzerland
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Ahlström M, Pekkinen M, Huttunen M, Lamberg-Allardt C. Dexamethasone down-regulates cAMP-phosphodiesterase in human osteosarcoma cells. Biochem Pharmacol 2004; 69:267-75. [PMID: 15627479 DOI: 10.1016/j.bcp.2004.09.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Accepted: 09/17/2004] [Indexed: 11/17/2022]
Abstract
Cyclic adenosine monophosphate (cAMP) is an important second messenger in the hormonal regulation of bone metabolism. cAMP is inactivated by the cyclic nucleotide phosphodiesterases (PDEs), a superfamily of enzymes divided into 11 known families, designated PDE1-11. Interference with the cAMP signaling pathway has been suggested as one mechanism causing glucocorticoid induced osteoporosis. We speculated that glucocorticoids could affect the cAMP pathway by a down-regulation of PDE-mediated cAMP hydrolysis. The main cAMP hydrolysing enzyme families of human MG-63 and SaOS-2 osteosarcoma cells were identified as PDE1 and PDE4 by assaying the PDE activity of Q-sepharose fractions and cell homogenates with selective inhibitors. Treatment with the glucocorticoid dexamethasone (Dex) decreased cAMP-PDE activity by up to 50%, without affecting cGMP-PDE activity. Dex treatment reduced the sensitivity of the total cAMP-PDE activity towards the PDE4 selective PDE inhibitor rolipram. Forskolin stimulated cAMP accumulation was increased 30-60-fold in the presence of rolipram. Treatment with Dex did not affect the basal or forskolin stimulated cAMP accumulation, but treatment resulted in a reduced effect of rolipram on cAMP accumulation. Expression of the following cAMP-PDE subtypes were detected by reverse transcriptase PCR (RT-PCR): PDE1A, PDE1C, PDE2A, PDE3A, PDE4A, PDE4B, PDE4C, PDE4D, PDE7A, PDE7B, PDE8A, PDE10A and PDE11A. Using semi-quantitative RT-PCR, we detected a 50-70% decrease in the mRNA of PDE4A and PDE4B subtypes following Dex treatment. Further analysis revealed that Dex reduced the PDE4A4 and PDE4B1 isoforms. PDE4A1 PDE4A, PDE4A7, PDE4A10, PDE4B2 were also expressed, but Dex did not affect the transcription of these isoforms. We conclude that Dex treatment could affect the cAMP signaling pathway of human osteosarcoma cells by reducing type 4 cAMP-phosphodiesterase (PDE4).
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Affiliation(s)
- Mikael Ahlström
- Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 66, Helsinki 00014, Finland.
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5
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McCarthy TL, Ji C, Chen Y, Kim K, Centrella M. Time- and dose-related interactions between glucocorticoid and cyclic adenosine 3',5'-monophosphate on CCAAT/enhancer-binding protein-dependent insulin-like growth factor I expression by osteoblasts. Endocrinology 2000; 141:127-37. [PMID: 10614631 DOI: 10.1210/endo.141.1.7237] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Glucocorticoid has complex effects on osteoblasts. Several of these changes appear to be related to steroid concentration, duration of exposure, or specific effects on growth factor expression or activity within bone. One important bone growth factor, insulin-like growth factor I (IGF-I), is induced in osteoblasts by hormones such as PGE2 that increase intracellular cAMP levels. In this way, PGE2 activates transcription factor CCAAT/enhancer-binding protein-delta (C/EBPdelta) and enhances its binding to a specific control element found in exon 1 in the IGF-I gene. Our current studies show that preexposure to glucocorticoid enhanced C/EBPdelta and C/EBPbeta expression by osteoblasts and thereby potentiated IGF-I gene promoter activation in response to PGE2. Importantly, this directly contrasts with inhibitory effects on IGF-I expression that result from sustained or pharmacologically high levels of glucocorticoid exposure. Consistent with the stimulatory effect of IGF-I on bone protein synthesis, pretreatment with glucocorticoid sensitized osteoblasts to PGE2, and in this context significantly enhanced new collagen and noncollagen protein synthesis. Therefore, pharmacological levels of glucocorticoid may reduce IGF-I expression by osteoblasts and cause osteopenic disease, whereas physiological transient increases in glucocorticoid may permit or amplify the effectiveness of hormones that regulate skeletal tissue integrity. These events appear to converge on the important role of C/EBPdelta and C/EBPbeta on IGF-I expression by osteoblasts.
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Affiliation(s)
- T L McCarthy
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut 06520-8041, USA.
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6
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Altavilla D, Squadrito F, Serrano M, Campo GM, Squadrito G, Arlotta M, Urna G, Sardella A, Saitta A, Caputi AP. Inhibition of tumour necrosis factor and reversal of endotoxin-induced shock by U-83836E, a 'second generation' lazaroid in rats. Br J Pharmacol 1998; 124:1293-9. [PMID: 9720803 PMCID: PMC1565499 DOI: 10.1038/sj.bjp.0701944] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
1. Antioxidants can exert protective effects in endotoxic shock by either a reduction of the oxidant damage or attenuation of Tumour Necrosis Factor (TNF-alpha) production. 2. Lazaroids are a family of compounds that inhibit lipid peroxidation. Besides, they can also reduce TNF-alpha. U-83836E is a new lazaroid lacking the glucocorticoid ring. 3. Aim of our study was to investigate the effect of U-83836E on TNF-alpha production either in vivo or in vitro. Endotoxic shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg kg(-1) of S. enteritidis lipopolysaccharide (LPS). LPS administration reduced survival rate (0% survival, 72 h after endotoxin administration), decreased mean arterial blood pressure, increased serum and macrophage TNF-alpha and enhanced plasma malonylaldehyde (MAL) levels. Furthermore aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (PE 1 nM-10 microM). 4. Treatment with U-83836E (7.5, 15 and 30 mg kg(-1), i.v.) 5 min after endotoxin challenge significantly protected against LPS induced lethality (90% survival rate and 80% survival rate 24 h and 72 h after LPS injection respectively, following the highest dose of the drug), reduced hypotension, blunted plasma MAL, decreased serum and macrophage TNF-alpha and restored the hyporeactivity of aortic rings to control values. In vitro LPS stimulation (50 microg ml(-1) for 4 h) significantly increased cytokine production in macrophages (Mphi) harvested from untreated normal rats. Pretreatment with pertussis toxin (PT; 0.1, 1 and 10 ng ml(-1) 4 h before LPS) significantly increased TNF-alpha production. PT effects on these LPS responses were correlated with a PT mediated ADP ribosylation of a 41 kDa protein. U-83836E (50 microM) reduced, in a dose dependent manner, LPS induced TNF-alpha production and inhibited the PT effects on cytokine production and on ADP ribosylation of the protein. 5. Our data suggest that lazaroids may affect the early events associated with LPS receptor mediated activation of a G protein in LPS induced TNF-alpha production. These molecular events may explain, at least in part, the in vivo inhibition of cytokine production and reversal of endotoxic shock.
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Affiliation(s)
- D Altavilla
- Institute of Pharmacology, School of Medicine, University of Messina, Italy
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7
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Hausmann S, Law FM, Bonjour JP, Feyen J, Rizzoli R. Regulation of parathyroid hormone/parathyroid hormone-related protein receptor expression by osteoblast-deposited extracellular matrix in a human osteoblast-like cell line. J Cell Physiol 1995; 165:164-71. [PMID: 7559797 DOI: 10.1002/jcp.1041650119] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Parathyroid hormone (PTH) receptors and the biological response to PTH in osteoblasts have been shown to be influenced by glucocorticoids, growth factors, cytokines or PTH itself. Furthermore, components of extracellular matrix (ECM) appear to regulate the response to PTH as well. We investigated the effects of osteoblast-deposited ECM on PTH-related protein (PTHrP)-stimulated cAMP production, PTHrP binding and PTH/PTHrP receptor mRNA in the human osteoblast-like cell line SaOS-2. ECM was laid down by the human osteoblastic cell line MG-63. At confluence, maximal cAMP stimulation induced by 100 nmol/l PTHrP (1-34) was decreased in SaOS-2 cells grown on ECM as compared with cultures on plastic dishes, without any change in PTHrP concentration producing half-maximal stimulation. In contrast, cAMP production stimulated by PGE2 was increased in cells on ECM. Saturable 125I-PTHrP binding (as evaluated by Scatchard plot analysis) was markedly diminished in cells grown on ECM (5,600 +/- 2,010 vs. 20,700 +/- 1,710 binding sites/cell, x +/- S.E.M., P < 0.01, n = 4 experiments), without any significant change in affinity (1.3 +/- 0.4 vs. 2.5 +/- 0.5 nmol/l (NS), in cells on ECM and plastic, respectively). This apparent decrease in membrane receptor density was associated with markedly lower steady state PTH/PTHrP receptor mRNA levels as assessed by Northern blot analysis (ECM/control: 0.4 +/- 0.1). A difference in PTH/PTHrP receptor mRNA levels between cells on ECM or on plastic dishes was detectable by 8 hours but not by 4 hours, after seeding the cells at high density. By 24 hours after plating, PTH/PTHrP receptor mRNA levels were maximally decreased in cells on ECM. These results in the human osteoblast-like cell line SaOS-2 indicate that PTH/PTHrP receptors are down-regulated by growth on ECM. Thus, attachment of bone cells to bone surface could influence differentiation and function of osteoblasts.
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Affiliation(s)
- S Hausmann
- Department of Medicine, University Hospital, Geneva, Switzerland
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8
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Nohutcu RM, Somerman MJ, McCauley LK. Dexamethasone enhances the effects of parathyroid hormone on human periodontal ligament cells in vitro. Calcif Tissue Int 1995; 56:571-7. [PMID: 7648489 DOI: 10.1007/bf00298592] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Periodontal ligament cells (PDL) are thought to play a major role in promoting periodontal regeneration. Recent studies, focused on characterizing PDL cells, have been directed at establishing their osteoblast-like properties and determining biological mediators and/or factors that induce osteoblastic cell populations in the PDL. The glucocorticoid, dexamethasone (Dex), has been shown to selectively stimulate osteoprogenitor cell proliferation and to induce osteoblastic cell differentiation in many cell systems. In the present study the ability of Dex to modulate parathyroid hormone (PTH)-stimulated cAMP synthesis in cultured human PDL cells was examined. PDL cells, obtained from premolar teeth extracted for orthodontic reasons, were cultured with Dex (0-1000 nM) for 7 days prior to PTH (1-34) stimulation. The exposure of PDL cells to Dex resulted in a dose-dependent increase in cAMP production in response to PTH stimulation. This response was seen in cells obtained from three different patients. The first significant Dex effect was seen on day 7 when compared to day 1 for 100 nM Dex. PTH (1-34) stimulation caused a dose-dependent increase in cAMP synthesis after Dex (1000 nM) treatment for 7 days. Conversely, stimulation of the cells with PTH (7-34) (0-1000 nM) did not increase cAMP production in PDL cells after Dex treatment. Forskolin- (1 microM) and isoproterenol- (1 microM) stimulated cAMP synthesis was not augmented by Dex treatment. Dex treatment did not alter calcitonin-(1 microM) stimulated cAMP production in PDL cells. Glucocorticoid enhancement of PTH-stimulated cAMP synthesis in these cells supports the presence of an osteoblast-like population in the PDL, in vitro.
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Affiliation(s)
- R M Nohutcu
- Department of Periodontics/Prevention/Geriatrics, University of Michigan, Ann Arbor 48109-1078, USA
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9
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Rao LG, Wylie JN. Modulation of parathyroid hormone-sensitive adenylate cyclase in ROS 17/2.8 cells by dexamethasone 1,25-dihydroxyvitamin D3 and protein kinase C. BONE AND MINERAL 1993; 23:35-47. [PMID: 8274878 DOI: 10.1016/s0169-6009(08)80089-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We tested whether the protein kinase C (PKC) modulation of PTH-sensitive adenylate cyclase in ROS 17/2.8 cells is affected by the glucocorticoid dexamethasone and the vitamin D hormone 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Basal and PTH- and forskolin-stimulated adenylate cyclase activities were determined in the presence or absence of 100 nM phorbol 12-myristate 13-acetate (PMA), the activator of PKC, in ROS 17/2.8 cells that had been previously cultured with or without dexamethasone or 1,25(OH)2D3. Dexamethasone treatment increased the basal, PMA-, PTH-, (PTH + PMA)- and (forskolin + PMA)-sensitive adenylate cyclase while 1,25(OH)2D3 decreased these effects. The stimulatory and inhibitory effects were dose-dependent with respect to dexamethasone and 1,25(OH)2D3, respectively. Dexamethasone increased, while 1,25(OH)2D3 decreased the maximal activity of both PTH-sensitive and PKC-modulated PTH-sensitive adenylate cyclase without affecting the half-maximal concentration (ED50) of PTH required for the activation of the enzyme. Additionally, dexamethasone, 1,25(OH)2D3 and PKC did not affect each other's ED50. Our results suggest that the effects of dexamethasone, 1,25(OH)2D3 and PKC on PTH-sensitive adenylate cyclase in ROS 17/2.8 cells are independent of each other.
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Affiliation(s)
- L G Rao
- Division of Endocrinology and Metabolism, St. Michael's Hospital, Toronto, Ontario, Canada
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10
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Suarez F, Rothhut B, Comera C, Touqui L, Marie FR, Silve C. Expression of annexin I, II, V, and VI by rat osteoblasts in primary culture: stimulation of annexin I expression by dexamethasone. J Bone Miner Res 1993; 8:1201-10. [PMID: 8256657 DOI: 10.1002/jbmr.5650081007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To determine whether rat osteoblasts synthesize proteins of the annexin family and to evaluate the extent to which glucocorticoids modulate the expression of annexins by these cells, osteoblasts were grown in primary cultures in the absence or presence of dexamethasone, and the expression of annexins was evaluated by immunoblotting using polyclonal antibodies against human annexins. Four different annexins (I, II, V, and VI) were found to be expressed by rat osteoblasts. The expression of annexin I, but not the other annexins studied, was increased in osteoblasts cultured in the presence of dexamethasone (173 +/- 33% increase comparing untreated cells and cells treated for 10 days with 5 x 10(-7) M dexamethasone). Increased expression of annexin I was observed after the third day of exposure to dexamethasone and rose thereafter until day 10; annexin I expression increased with dexamethasone concentrations above 10(-10) M throughout the range of concentrations studied. The increase in annexin I protein was associated with an increase in annexin I mRNA and was completely blocked by the concomitant addition of the glucocorticoid receptor antagonist RU 38486. The increase in annexin I content following dexamethasone treatment was associated with an increase in alkaline phosphatase activity and PTH-induced cAMP stimulation, whereas phospholipase A2 activity in the culture medium was reduced to undetectable levels. The finding that four annexins are expressed in rat osteoblasts in primary culture raises the possibility that these proteins could play an important role in bone formation by virtue of their ability to bind calcium and phospholipids, serve as Ca2+ channels, interact with cytoskeletal elements, and/or regulate phospholipase A2 activity. In addition, the dexamethasone-induced increase in annexin I may represent a mechanism by which glucocorticoids modify osteoblast function.
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Affiliation(s)
- F Suarez
- CNRS URA 583, Hôpital Necker Enfants Malades, Paris, France
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11
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Woods DB, Thangavelu V, Barling PM. Down-regulation of adenylate cyclase-coupled response to native bovine parathyroid hormone and fragments in the osteoblast-like cell line UMR-106. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1992; 24:421-5. [PMID: 1551456 DOI: 10.1016/0020-711x(92)90034-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. Parathyroid hormone-induced down-regulation was studied in the osteosarcoma cell line UMR-106. 2. A maximal priming does of bPTH (1-84) down-regulated PTH-responsiveness to 40% of its initial value; bPTH (1-41) was less effective than bPTH (1-84), whereas bPTH (42-84) had no effect, alone or in combination with bPTH (1-41). 3. A tentative model for the function of different domains of parathyroid hormone in down-regulation is suggested.
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Affiliation(s)
- D B Woods
- St Bartholomews Hospital, London, England
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12
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Wong MM, Rao LG, Ly H, Hamilton L, Tong J, Sturtridge W, McBroom R, Aubin JE, Murray TM. Long-term effects of physiologic concentrations of dexamethasone on human bone-derived cells. J Bone Miner Res 1990; 5:803-13. [PMID: 2173356 DOI: 10.1002/jbmr.5650050803] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Bone cells derived from human trabecular explants display osteoblastic features. We examined the modulation of alkaline phosphatase activity and cAMP production as the result of exposing trabecular explants to physiologic concentrations of dexamethasone for 4 weeks during cellular outgrowth and subculture. Cells treated with dexamethasone were observed to grow generally more slowly than control cells. Cells appeared larger and more polygonal, and staining for alkaline phosphatase was more intense in the dexamethasone-exposed cultures. There was a progressive increase in cellular PTH responsiveness with increasing duration of exposure of cells to dexamethasone. Cells grown for 6 weeks in 3 x 10(-8) M dexamethasone had a 10-fold increase in PTH-stimulated cyclic AMP accumulation. Dexamethasone-treated cells also had a significantly increased alkaline phosphatase activity. 1,25-(OH)2D3-stimulated alkaline phosphatase activity was increased approximately 20-fold. cAMP responses were significantly increased to PTH (21.7-fold), PGE1 (2.67-fold), and forskolin (4.81-fold), but not to cholera toxin. Dexamethasone-treated cells also had a mean decrease in 1,25-(OH)2D3-stimulated osteocalcin production to 26.2% of control values (p less than 0.001). Hydrocortisone treatment gave rise to similar effects but of smaller magnitude than those of dexamethasone. Testosterone did not have a significant effect on alkaline phosphatase activity or cAMP production. Skin fibroblasts showed a significant enhancement of alkaline phosphatase activity in response to dexamethasone, but of a much smaller magnitude than in bone cells. The phenotypic changes induced by long-term culture in dexamethasone are consistent with the promotion of a more differentiated osteoblastic phenotype.
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Affiliation(s)
- M M Wong
- Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada
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13
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Shapiro S, Tatakis DN, Dziak R. Effects of tumor necrosis factor alpha on parathyroid hormone-induced increases in osteoblastic cell cyclic AMP. Calcif Tissue Int 1990; 46:60-2. [PMID: 2153041 DOI: 10.1007/bf02555826] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tumor necrosis factor alpha (10(-10) - 10(-8) M) had no effects on cyclic AMP production by the osteoblastic osteosarcomal cells, Saos-2 and G292, or normal rat calvarial cells. The cytokine did, however, inhibit the parathyroid hormone (PTH)-induced effect on cyclic AMP in the Saos-2 and normal rat osteoblastic cells. This inhibitory effect did not occur on prostaglandin E2-induced cyclic AMP increases in the osteoblastic cells. Interleukin-1 (10 U/ml-100 U/ml) did not produce any effect on basal levels or PTH-induced cyclic AMP increases in these cells.
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Affiliation(s)
- S Shapiro
- SUNY-Buffalo, School of Dental Medicine, Department of Oral Biology 14214
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14
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Abstract
Many cells and their cytokines produce a significant effect on bone metabolism. Bone matrix synthesis is a function of the osteoblast (Fig 1), influenced directly by numerous local and systemic factors (Tables 1 and 2). Locally synthesized factors such as SGF, BMP, and BDGF may be particularly important in stimulating new bone formation at sites of bone resorption or following bony injury. Of the systemic factors, GH; somatomedin C (IGF-1); high concentrations of insulin, testosterone, PDGF and TGF beta; and low concentrations of PGE2 and IL-1 appear to stimulate bone formation in vitro. These latter factors may be more important in maintaining skeletal growth and bone mass. Bone resorption by osteoclasts (Figs 2 and 3) is also controlled by the osteoblast, as this cell produces a leukotriene-dependent polypeptide that stimulates osteoclastic bone resorption. Osteoblasts cover the periosteal and endosteal bone-surfaces and limit exposure of the underlying bone to osteoclasts. PTH, vitamin D, PGE2, and other systemic factors interact directly with the osteoblast, not the osteoclast. Surface receptor binding of PTH increases intracellular cAMP and calcium and results in release of the factor that stimulates osteoclastic bone resorption. PGE2 induces osteoblasts to activate osteoclasts and is a major controlling factor in bone metabolism; the osteoblast produces PGE2, which can then modify osteoblastic function by positive feedback. Although low concentrations of PGE2 stimulate bone formation, higher concentrations promote osteoblast-mediated bone resorption. Furthermore, many of the systemic factors stimulate bone resorption via a PGE2-associated mechanism. Immune cytokines also appear to exert a profound influence on bone metabolism. INF-gamma inhibits osteoclastic resorption, whereas IL-1, TNF, and LT strongly stimulate bone resorption. However, low concentrations of IL-1 paradoxically result in stimulation of bone formation. These cytokines, particularly in various combinations, may prove extremely important in understanding and treating the bone loss associated with malignancies, osteoporosis, and rheumatoid arthritis.
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Affiliation(s)
- D A Watrous
- Department of Medicine, University of California, Irvine 92717
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15
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Balmforth AJ, Yasunari K, Vaughan PF, Ball SG. Glucocorticoids modify differentially dopamine- and prostaglandin E1-mediated cyclic AMP formation by the cultured human astrocytoma clone D384. J Neurochem 1989; 52:1613-8. [PMID: 2540279 DOI: 10.1111/j.1471-4159.1989.tb09216.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effects of steroid hormones on the cyclic AMP responses to stimulation of human astrocytoma cells (D384) by dopamine, prostaglandin E1 (PGE1), and isoprenaline were investigated. Incubation of D384 cells with dexamethasone resulted in a potentiation of the PGE1 and isoprenaline responses and a marked attenuation of the dopamine response. The time courses of the effects of dexamethasone on dopamine and PGE1 responses were similar, requiring long-term (at least 18 h) incubation of cells with the steroid. Concentration-response curves of dexamethasone effects on dopamine and PGE1 responses yielded similar Ka apparent values, suggesting a common mechanism. Cycloheximide, a protein synthesis inhibitor, prevented the effects of dexamethasone. Only steroids with glucocorticoid activity reproduced the dexamethasone effects. Direct stimulation of Gs with 5-guanylylimidodiphosphate and adenylate cyclase with forskolin revealed no significant differences in their activities in dexamethasone-treated and untreated cells. Furthermore, a comparison of the dopamine and PGE1 concentration-response curves obtained from dexamethasone-treated and untreated cells suggested that the affinity of the receptors for their agonists remained unchanged. These results suggest that glucocorticoids may alter protein synthesis and thereby the number of receptors expressed by D384 cells.
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Affiliation(s)
- A J Balmforth
- M.R.C. Blood Pressure Unit, Western Infirmary, Glasgow, Scotland
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16
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Silve C, Fritsch J, Grosse B, Tau C, Edelman A, Delmas P, Balsan S, Garabedian M. Corticosteroid-induced changes in the responsiveness of human osteoblast-like cells to parathyroid hormone. BONE AND MINERAL 1989; 6:65-75. [PMID: 2546639 DOI: 10.1016/0169-6009(89)90024-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We investigated the in vitro effect of corticosteroids on the responsiveness of human cells of osteoblast lineage to parathyroid hormone (PTH). Prior to corticosteroid treatment, the cells demonstrated only a small increase in cAMP production and no measurable change in transmembrane potential in response to PTH. Exposure of cells to dexamethasone resulted in a 5-fold increase in PTH-induced cAMP production and in measurable PTH-induced membrane depolarization in all cells studied. The effect of corticosteroids on cAMP production was specific for PTH (not seen with PGE1 or forskolin), occurred in a time- and dose-dependent fashion and in the absence of cell proliferation. Most of the cells were of osteoblast lineage as determined by the presence of alkaline phosphatase activity and BGP secretion. These findings further support the idea that corticosteroids increase the sensitivity of cells of osteoblast lineage to PTH, perhaps by transforming cells which initially have a low responsiveness to PTH to a state of high responsiveness.
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Affiliation(s)
- C Silve
- Laboratoire du Calcium et Tissu Osseux dans l'Organisme en Développement, CNRS UA.583, Hôpital des Enfants-Malades, Paris, France
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17
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Rizzoli R, Bonjour JP. Effect of pertussis toxin on parathyroid hormone-stimulated cyclic AMP production in cultured kidney cells. J Bone Miner Res 1988; 3:605-9. [PMID: 2855189 DOI: 10.1002/jbmr.5650030605] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of pertussis toxin, which inactivates the guanine nucleotide binding regulatory proteins Gi and Go on cAMP production in response to parathyroid hormone PGE2 or forskolin, was examined in confluent opossum kidney (OK) cells. This effect was compared with that caused by dexamethasone. The response to PTH was increased in cells preincubated with either agent. The effect of pertussis toxin was selective for PTH, since cAMP production in response to neither PGE2 nor forskolin was increased. In contrast, the response to forskolin was enhanced in dexamethasone-treated cells. These results indicate that both stimulatory and inhibitory guanine nucleotides binding regulatory proteins modulate PTH-induced cAMP production in OK cells. Moreover, pertussis toxin and dexamethasone appear to affect different levels of the PTH-receptor-adenylate cyclase complex.
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Affiliation(s)
- R Rizzoli
- Department of Medicine, University Hospital of Geneva, Switzerland
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18
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Pasquier YN, Pecquery R, Giudicelli Y. Increased adenylate cyclase catalytic activity explains how estrogens "in vivo" promote lipolytic activity in rat white fat cells. Biochem Biophys Res Commun 1988; 154:1151-9. [PMID: 2457367 DOI: 10.1016/0006-291x(88)90261-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Estradiol administration (5 micrograms per day x 4 days) to ovariectomized rats resulted in a 60-70% increase in the maximal lipolytic response of their white adipocytes to isoproterenol, epinephrine, IBMX and forskolin. These altered lipolytic responses were accompanied by parallel changes in the intracellular cyclic AMP levels found in response to 1 mM IBMX alone (+ 106%) or combined with submaximal concentrations of isoproterenol (+205%), epinephrine (+190%) and forskolin (235%). Studies of the adenylate cyclase activity revealed an overall increase in the stimulatory responsiveness of the enzyme (+150 to +200%) after the estradiol-treatment, regardless of the stimulatory agents tested (GTP, GppNHp, fluoride, isoproterenol, ACTH, forskolin). Finally, the finding of a 2-fold enhancement of the Mn2+ (+/- GDP beta S)-stimulated adenylate cyclase activity after the estradiol-treatment strongly suggests that increased activity of the catalytic subunit of this enzyme is the likely mechanism whereby estrogens promote lipolysis in rat fat cells.
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Affiliation(s)
- Y N Pasquier
- Department of Biochemistry, Faculty of Medicine Paris-Ouest, Poissy, France
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19
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Lacasa D, Agli B, Giudicelli Y. Permissive action of glucocorticoids on catecholamine-induced lipolysis: direct "in vitro" effects on the fat cell beta-adrenoreceptor-coupled-adenylate cyclase system. Biochem Biophys Res Commun 1988; 153:489-97. [PMID: 2838019 DOI: 10.1016/s0006-291x(88)81121-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Exposure of adipose tissue fragments to dexamethasone leads to enhanced lipolytic and cyclic AMP responses of isolated fat cells to isoproterenol. This permissive effect of the steroid is dose-dependent, prevented by the glucocorticoid receptor antagonist RU 38486, maximum after 48 h exposure to 10 nM dexamethasone and affects only the amplitude of the maximal response (+50%). Exposure to dexamethasone also induces an increase in both the number of beta-adrenergic receptors (+30%), and the adenylate cyclase-catalytic activity (+64%) and - responses to GTP (+114%) and isoproterenol (+55%). These data strongly suggest that the permissive effect of glucocorticoids towards lipolysis "in vivo" results at least in part from a glucocorticoid-receptor mediated action of these hormones on the fat cell membranous components involved in the beta-adrenergic control of lipolysis.
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Affiliation(s)
- D Lacasa
- Department of Biochemistry, Faculty of Medecine Paris-Quest, C.H.I., Poissy, France
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Malbon CC, Rapiejko PJ, Watkins DC. Permissive hormone regulation of hormone-sensitive effector systems. Trends Pharmacol Sci 1988; 9:33-6. [PMID: 3072728 DOI: 10.1016/0165-6147(88)90240-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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21
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Gutierrez GE, Mundy GR, Derynck R, Hewlett EL, Katz MS. Inhibition of parathyroid hormone-responsive adenylate cyclase in clonal osteoblast-like cells by transforming growth factor alpha and epidermal growth factor. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47665-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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22
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Rizzoli R, Bonjour JP. Effect of dexamethasone on parathyroid hormone stimulation of cyclic AMP in an opossum kidney cell line. J Cell Physiol 1987; 132:517-23. [PMID: 2443515 DOI: 10.1002/jcp.1041320314] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The influence of the glucocorticoid dexamethasone on the cAMP response to parathyroid hormone (PTH) and various agonists was studied in epithelial monolayers of opossum kidney (OK) cells. The incubation with dexamethasone for 72 hours led to a dose-dependent higher cAMP response to PTH or forskolin in intact cells as well as in digitonin-permeabilized cells. This effect did not appear to result from changes in phosphodiesterase (PDE) activity nor from alterations in cAMP efflux from the cells. Moreover, dexamethasone increased the formation of domes by OK cell epithelium. Thus, dexamethasone seems to promote a more differentiated renal epithelial phenotype as suggested by enhanced hormonal response.
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Affiliation(s)
- R Rizzoli
- Department of Medicine, University Hospital, Geneva, Switzerland
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