1
|
Civitelli R, Bilezikian JP, Potts JT, Stern PH. In Memoriam: William A. Peck, MD. J Bone Miner Res 2023. [PMID: 37055026 DOI: 10.1002/jbmr.4813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 03/21/2023] [Indexed: 04/15/2023]
Affiliation(s)
- Roberto Civitelli
- Division of Bone and Mineral Diseases, Department of Medicine, Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, MO, USA
| | - John P Bilezikian
- Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - John T Potts
- Massachusetts General Hospital, Harvard University, Boston, MA, USA
| | - Paula H Stern
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| |
Collapse
|
2
|
Avilla MN, Bradfield CA, Glover E, Hahn ME, Malecki KMC, Stern PH, Wilson RH. Alan Poland, MS, MD: 1940-2020 Poisons as Probes of Biological Function. Chem Res Toxicol 2020; 34:1-4. [PMID: 33345537 DOI: 10.1021/acs.chemrestox.0c00159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
3
|
Affiliation(s)
- Annette Gilchrist
- Department of Pharmaceutical Sciences, Midwestern University, Downers Grove, IL, United States
| | - Paula H. Stern
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| |
Collapse
|
4
|
Edwards BJ, Gradishar WJ, Smith ME, Pacheco JA, Holbrook J, McKoy JM, Nardone B, Tica S, Godinez-Puig V, Rademaker AW, Helenowski IB, Bunta AD, Stern PH, Rosen ST, West DP, Guise TA. Elevated incidence of fractures in women with invasive breast cancer. Osteoporos Int 2016; 27:499-507. [PMID: 26294292 DOI: 10.1007/s00198-015-3246-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/08/2015] [Indexed: 01/13/2023]
Abstract
UNLABELLED This study evaluates the incidence of bone fractures in women with BC.We found that women with invasive breast cancer are at an increased risk for bone fractures, with fractures most commonly occurring at lower extremity and vertebral sites. The risk is further increased in women undergoing cancer therapy. INTRODUCTION Bone loss and fractures in breast cancer have generally been attributed to aromatase inhibitor use. This study assessed the incidence of fractures after invasive breast cancer diagnosis and evaluated bone density and FRAX risk calculation at time of fracture occurrence. METHODS Retrospective cohort study of women with invasive breast cancer [June 2003-December 2011] who participated in an academic hospital based genetic biobank. Demographic and clinical characteristics were abstracted from the electronic medical record (EMR). RESULTS A total of 422 women with invasive breast cancer were assessed; 79 (28 %) sustained fractures during the observation period; fractures occurred at multiple skeletal sites in 27 cases (116 fractures). The incidence of fractures was 40 per 1000 person-years. Women who sustained fractures were mostly white and had a family history of osteoporosis (36.9 %, p = 0.03) or history of a prior fracture (6/79, p = 0.004). Fractures occurred 4.0 years (range 0-12 years) after cancer diagnosis. Fracture cases had femoral neck bone mineral density (BMD) of 0.72 + 0.12 g/cm(2), T-score of -1.2, that is, within the low bone mass range. Fractures most commonly occurred in lower extremities, vertebral, and wrist sites. Hip fractures accounted for 11 % of fractures, occurring at a median age of 61 years. CONCLUSIONS Fractures occur shortly after commencing cancer therapy. Rapid bone loss associated with cancer therapy may precipitate fractures. Fractures occur at relatively higher BMD in BC. Occurrence of fractures in invasive breast cancer raises the possibility of cancer-induced impairment in bone quality.
Collapse
Affiliation(s)
- B J Edwards
- Department of General Internal Medicine, University of Texas, MD Anderson Cancer Center, 1515 Holcombe, unit 1465, Houston, TX, 77030, USA.
| | - W J Gradishar
- Robert H. Lurie Comprehensive Cancer Center, Chicago, IL, USA
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - M E Smith
- NUgene Project, Center for Genetic Medicine, Northwestern University, Chicago, IL, USA
| | - J A Pacheco
- NUgene Project, Center for Genetic Medicine, Northwestern University, Chicago, IL, USA
| | - J Holbrook
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - J M McKoy
- Robert H. Lurie Comprehensive Cancer Center, Chicago, IL, USA
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - B Nardone
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - S Tica
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - V Godinez-Puig
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - A W Rademaker
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - I B Helenowski
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - A D Bunta
- Department of Orthopaedic Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - P H Stern
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - S T Rosen
- Robert H. Lurie Comprehensive Cancer Center, Chicago, IL, USA
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - D P West
- Robert H. Lurie Comprehensive Cancer Center, Chicago, IL, USA
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - T A Guise
- Department of Medicine, Division of Endocrinology, Indiana University, Indianapolis, IN, USA
| |
Collapse
|
5
|
Stern PH, Alvares K. Antitumor agent cabozantinib decreases RANKL expression in osteoblastic cells and inhibits osteoclastogenesis and PTHrP-stimulated bone resorption. J Cell Biochem 2015; 115:2033-8. [PMID: 25042887 DOI: 10.1002/jcb.24879] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 07/09/2014] [Indexed: 11/08/2022]
Abstract
Cabozantinib, an inhibitor of vascular endothelial growth factor and hepatocyte growth factor signaling, decreases bone lesions in patients with prostate cancer. To determine direct effects of cabozantinib on bone, resorption in neonatal mouse bone organ culture and on gene expression, proliferation, and phenotypic markers in osteoblast and osteoclast cell lines were examined. Cabozantinib, 0.3 and 3 µM, prevented PTHrP-stimulated calcium release from neonatal mouse calvaria. Since the effect on resorption could reflect effects on osteoblasts to prevent osteoclast activation, or direct inhibition of osteoclasts, responses in osteoblastic and osteoclast precursor cell lines were examined. Twenty-four-hour treatment of osteoblastic MC3T3-E1 cells with 3 µM cabozantinib decreased expression of receptor activator of NFkB ligand (RANKL) and alkaline phosphatase. Forty-eight-hour treatment of MC3T3-E1 cells with 3 µM cabozantinib inhibited cell proliferation and decreased MTT activity. Effects on alkaline phosphatase activity were biphasic, with small stimulatory effects at concentrations below 3 µM. When RAW 264.7 osteoclast precursor cells differentiated with 20 ng/ml RANKL were co-treated for 24 h with 3 µM cabozantinib, expression of RANK, TRAP, cathepsin K, alpha v or beta 3 integrin, or NFATc1 were unaffected. Five-day treatment of RANKL-treated RAW 264.7 cells with 3 µM cabozantinib decreased TRAP and MTT activity. The results suggest that the osteoblast could be the initial target, with subsequent direct and indirect effects on osteoclastogenesis leading to decreased resorption. The multiple effects of cabozantinib on the cell microenvironment of bone are consistent with its effectiveness in reducing lesions from prostate cancer metastases.
Collapse
Affiliation(s)
- Paula H Stern
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | | |
Collapse
|
6
|
Alvares K, Stern PH, Veis A. Dentin phosphoprotein binds annexin 2 and is involved in calcium transport in rat kidney ureteric bud cells. J Biol Chem 2013; 288:13036-45. [PMID: 23525114 DOI: 10.1074/jbc.m112.389627] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dentin phosphoprotein (DPP) is the most abundant noncollagenous protein in the dentin, where it plays a major role in the mineralization of dentin. However, we and others have shown that in addition to being present in the dentin, DPP is also present in nonmineralizing tissues like the kidney, lung, and salivary glands, where it conceivably has other functions such as in calcium transport. Because annexins have been implicated as calcium transporters, we examined the relationships between DPP and annexins. In this report, we show that DPP binds to annexin 2 and 6 present in a rat ureteric bud cell line (RUB1). Immunofluorescence studies show that annexin 2 and DPP colocalize in these cells. In addition, DPP and annexin 2 colocalize in the ureteric bud branches of embryonic metanephric kidney. In the RUB1 cells and ureteric bud branches of embryonic kidney, colocalization was restricted to the cell membrane. Studies on calcium influx into RUB cells show that in the presence of anti-DPP, there was a 40% reduction of calcium influx into these cells. We postulate that DPP has different functions in the kidney as compared with the odontoblasts. In the odontoblasts, its primary function is in the extracellular mineralization of dentin, whereas in the kidney it may participate in calcium transport.
Collapse
Affiliation(s)
- Keith Alvares
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
| | | | | |
Collapse
|
7
|
Edwards BJ, Bunta AD, Lane J, Odvina C, Rao DS, Raisch DW, McKoy JM, Omar I, Belknap SM, Garg V, Hahr AJ, Samaras AT, Fisher MJ, West DP, Langman CB, Stern PH. Bisphosphonates and nonhealing femoral fractures: analysis of the FDA Adverse Event Reporting System (FAERS) and international safety efforts: a systematic review from the Research on Adverse Drug Events And Reports (RADAR) project. J Bone Joint Surg Am 2013; 95:297-307. [PMID: 23426763 PMCID: PMC3748968 DOI: 10.2106/jbjs.k.01181] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND In the United States, hip fracture rates have declined by 30% coincident with bisphosphonate use. However, bisphosphonates are associated with sporadic cases of atypical femoral fracture. Atypical femoral fractures are usually atraumatic, may be bilateral, are occasionally preceded by prodromal thigh pain, and may have delayed fracture-healing. This study assessed the occurrence of bisphosphonate-associated nonhealing femoral fractures through a review of data from the U.S. FDA (Food and Drug Administration) Adverse Event Reporting System (FAERS) (1996 to 2011), published case reports, and international safety efforts. METHODS We analyzed the FAERS database with use of the proportional reporting ratio (PRR) and empiric Bayesian geometric mean (EBGM) techniques to assess whether a safety signal existed. Additionally, we conducted a systematic literature review (1990 to February 2012). RESULTS The analysis of the FAERS database indicated a PRR of 4.51 (95% confidence interval [CI], 3.44 to 5.92) for bisphosphonate use and nonhealing femoral fractures. Most cases (n = 317) were attributed to use of alendronate (PRR = 3.32; 95% CI, 2.71 to 4.17). In 2008, international safety agencies issued warnings and required label changes. In 2010, the FDA issued a safety notification, and the American Society for Bone and Mineral Research (ASBMR) issued recommendations about bisphosphonate-associated atypical femoral fractures. CONCLUSIONS Nonhealing femoral fractures are unusual adverse drug reactions associated with bisphosphonate use, as up to 26% of published cases of atypical femoral fractures exhibited delayed healing or nonhealing.
Collapse
Affiliation(s)
- Beatrice J. Edwards
- Bone Health and Osteoporosis Center, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair, Suite 1350, Chicago, IL 60611
| | - Andrew D. Bunta
- Bone Health and Osteoporosis Center, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair, Suite 1350, Chicago, IL 60611
| | - Joseph Lane
- Hospital for Special Surgery, Weill Cornell Medical College, 535 East 70th Street, New York, NY 10021
| | - Clarita Odvina
- University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390
| | - D. Sudhaker Rao
- Division of Endocrinology, Diabetes, and Bone and Mineral Metabolism, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI 48202
| | - Dennis W. Raisch
- Department of Pharmacy Practice and Administrative Sciences, Nursing/Pharmacy Building, Room B94, University of New Mexico, Albuquerque, NM 87131
| | - June M. McKoy
- Division of Geriatric Medicine, Feinberg School of Medicine, Northwestern University, 645 North Michigan, Suite 630, Chicago, IL 60611
| | - Imran Omar
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair, Suite 800, Chicago, IL 60611
| | - Steven M. Belknap
- Department of Dermatology, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair, Suite 1600, Chicago, IL 60611
| | - Vishvas Garg
- Department of Pharmacy Practice and Administrative Sciences, Nursing/Pharmacy Building, Room B94, University of New Mexico, Albuquerque, NM 87131
| | - Allison J. Hahr
- Division of Endocrinology, Department of Medicine, Feinberg School of Medicine, Northwestern University, 645 North Michigan, Suite 530, Chicago, IL 60611
| | - Athena T. Samaras
- Robert H. Lurie Comprehensive Cancer Center, 676 North Saint Clair, Suite 1600, Chicago, IL 60611
| | - Matthew J. Fisher
- Division of Geriatric Medicine, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair, Suite 1600, Chicago, IL 60611
| | - Dennis P. West
- Department of Dermatology, Feinberg School of Medicine, Northwestern University, 676 North Saint Clair, Suite 1600, Chicago, IL 60611
| | - Craig B. Langman
- Ann and Robert H. Lurie Children’s Hospital of Chicago, Box MS37, 225 East Chicago Avenue, Chicago, IL 60611
| | - Paula H. Stern
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, 645 North Michigan, Suite 630, Chicago, IL 60611
| |
Collapse
|
8
|
Abstract
Vitamin D is important for the normal development and maintenance of bone. The elucidation of the vitamin D activation pathway and the cloning of the vitamin D receptor have advanced our understanding of the actions of vitamin D on bone. The preponderance of evidence indicates that 1,25(OH)₂D₃ enhances bone mineralization through its effects to promote calcium and phosphate absorption. Although 1,25(OH)₂D₃ stimulates bone resorption in vitro, treatment in vivo can prevent bone loss and fracture through several potential mechanisms. The development of vitamin D analogues has provided new therapeutic options for increasing bone mineral density and reducing fractures.
Collapse
Affiliation(s)
- Tomohiko Yoshida
- Division of Endocrinology, Diabetes and Metabolism, Chiba University Hospital, 1-8-1 Inohana, Chiba-shi, Chiba 260-8670, Japan
| | | |
Collapse
|
9
|
Hu Z, Gupta J, Zhang Z, Gerseny H, Berg A, Chen YJ, Zhang Z, Du H, Brendler CB, Xiao X, Pienta KJ, Guise T, Lee C, Stern PH, Stock S, Seth P. Systemic delivery of oncolytic adenoviruses targeting transforming growth factor-β inhibits established bone metastasis in a prostate cancer mouse model. Hum Gene Ther 2012; 23:871-82. [PMID: 22551458 DOI: 10.1089/hum.2012.040] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We have examined whether Ad.sTβRFc and TAd.sTβRFc, two oncolytic viruses expressing soluble transforming growth factor-β receptor II fused with human Fc (sTGFβRIIFc), can be developed to treat bone metastasis of prostate cancer. Incubation of PC-3 and DU-145 prostate tumor cells with Ad.sTβRFc and TAd.sTβRFc produced sTGFβRIIFc and viral replication; sTGFβRIIFc caused inhibition of TGF-β-mediated SMAD2 and SMAD3 phosphorylation. Ad(E1-).sTβRFc, an E1(-) adenovirus, produced sTGFβRIIFc but failed to replicate in tumor cells. To examine the antitumor response of adenoviral vectors, PC-3-luc cells were injected into the left heart ventricle of nude mice. On day 9, mice were subjected to whole-body bioluminescence imaging (BLI). Mice bearing hind-limb tumors were administered viral vectors via the tail vein on days 10, 13, and 17 (2.5×10(10) viral particles per injection per mouse, each injection in a 0.1-ml volume), and subjected to BLI and X-ray radiography weekly until day 53. Ad.sTβRFc, TAd.sTβRFc, and Ad(E1-).sTβRFc caused significant inhibition of tumor growth; however, Ad.sTβRFc was the most effective among all the vectors. Only Ad.sTβRFc and TAd.sTβRFc inhibited tumor-induced hypercalcemia. Histomorphometric and synchrotron micro-computed tomographic analysis of isolated bones indicated that Ad.sTβRFc induced significant reduction in tumor burden, osteoclast number, and trabecular and cortical bone destruction. These studies suggest that Ad.sTβRFc and TAd.sTβRFc can be developed as potential new therapies for prostate cancer bone metastasis.
Collapse
Affiliation(s)
- Zebin Hu
- Gene Therapy Program, Department of Medicine, NorthShore Research Institute, Evanston, IL 60201, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Abstract
Estrogen and androgen are both critical for the maintenance of bone, but the target cells, mechanisms, and responses could be sex-specific. To compare sex-specific actions of estrogen and androgen on osteoclasts, human peripheral blood mononuclear precursor cells from adult Caucasian males (n = 3) and females (n = 3) were differentiated into osteoclasts and then treated for 24 h with 17β-estradiol (10 nM) or testosterone (10 nM). Gene expression was studied with a custom designed qPCR-based array containing 94 target genes related to bone and hormone action. In untreated osteoclasts, 4 genes showed significant gender differences. 17β-estradiol significantly affected 12 genes in osteoclasts from females and 6 genes in osteoclasts from males. Fifteen of the 18 17β-estradiol-responsive genes were different in the cells from the two sexes; 2 genes affected by 17β-estradiol in both sexes were regulated oppositely in the two sexes. Testosterone significantly affected 6 genes in osteoclasts from females and 2 genes in osteoclasts from males; all except one were different in the two sexes. 17β-estradiol and testosterone largely affected different genes, suggesting that conversion of testosterone to 17β-estradiol had a limited role in the responses. The findings indicate that although osteoclasts from both sexes respond to 17β-estradiol and testosterone, the effects of both 17β-estradiol and testosterone differ in the two sexes, highlighting the importance of considering gender in the design of therapy.
Collapse
Affiliation(s)
- Jun Wang
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | | |
Collapse
|
11
|
Abstract
Breast cancer patients have an extremely high rate of bone metastases. Morphological analyses of the bones in most of the patients have revealed the mixed bone lesions, comprising both osteolytic and osteoblastic elements. β-Catenin plays a key role in both embryonic skeletogenesis and postnatal bone regeneration. Although this pathway is also involved in many bone malignancy, such as osteosarcoma and prostate cancer-induced bone metastases, its regulation of breast cancer bone metastases remains unknown. Here, we provide evidence that the β-catenin signaling pathway has a significant impact on the bone lesion phenotype. In this study, we established a novel mouse model of mixed bone lesions using intratibial injection of TM40D-MB cells, a breast cancer cell line that is highly metastatic to bone. We found that both upstream and downstream molecules of the β-catenin pathway are up-regulated in TM40D-MB cells compared with non-bone metastatic TM40D cells. TM40D-MB cells also have a higher T cell factor (TCF) reporter activity than TM40D cells. Inactivation of β-catenin in TM40D-MB cells through expression of a dominant negative TCF4 not only increases osteoclast differentiation in a tumor-bone co-culture system and enhances osteolytic bone destruction in mice, but also inhibits osteoblast differentiation. Surprisingly, although tumor cells overexpressing β-catenin did induce a slight increase of osteoblast differentiation in vitro, these cells display a minimal effect on osteoblastic bone formation in mice. These data collectively demonstrate that β-catenin acts as an important determinant in mixed bone lesions, especially in controlling osteoblastic effect within tumor-harboring bone environment.
Collapse
Affiliation(s)
- Yan Chen
- Department of Molecular Pharmacology and Biological Chemistry, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Heidi Y Shi
- Department of Molecular Pharmacology and Biological Chemistry, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Stuart R Stock
- Department of Molecular Pharmacology and Biological Chemistry, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Paula H Stern
- Department of Molecular Pharmacology and Biological Chemistry, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Ming Zhang
- Department of Molecular Pharmacology and Biological Chemistry, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611.
| |
Collapse
|
12
|
Stern PH, Wang J. Sex‐specific gene responses to estrogen and androgen in human osteoclasts. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.lb391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Paula H Stern
- Dept of Molecular Pharmacology and Biological ChemistryNorthwestern UniversityChicagoIL
| | - Jun Wang
- Dept of Molecular Pharmacology and Biological ChemistryNorthwestern UniversityChicagoIL
| |
Collapse
|
13
|
Wang J, Stern PH. Osteoclastogenic activity and RANKL expression are inhibited in osteoblastic cells expressing constitutively active Gα(12) or constitutively active RhoA. J Cell Biochem 2011; 111:1531-6. [PMID: 20872746 DOI: 10.1002/jcb.22883] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Gα(12)-RhoA signaling is a parathyroid hormone (PTH)-stimulated pathway that mediates effects in bone and may influence genetic susceptibility to osteoporosis. To further elucidate effects of the pathway in osteoblasts, UMR-106 osteoblastic cells were stably transfected with constitutively active (ca) Gα(12) or caRhoA or dominant negative (dn) RhoA and co-cultured with RAW 264.7 cells to determine effects on hormone-stimulated osteoclastogenesis. Whereas PTH and calcitriol-stimulated osteoclastogenesis in co-cultures with UMR-106 cells expressing pcDNA or dominant negative RhoA, the osteoclastogenic effects of PTH and calcitriol were significantly attenuated when the UMR-106 cells expressed either caRhoA or caGα(12). These inhibitory effects were partially reversed by the Rho kinase inhibitor Y27632. None of the constructs affected osteoclastogenesis in untreated co-cultures, and the constructs did not inhibit the osteoclastogenic responses to receptor activator of NFκB ligand (RANKL). To investigate the mechanism of the inhibitory effects of caGα(12) and caRhoA, expression of RANKL, osteoprotegerin (OPG), osteopontin (OPN), and intercellular adhesion molecule-1 (ICAM) in response to PTH or calcitriol was examined in the UMR-106 cells. In the cells expressing pcDNA or dnRhoA, PTH and calcitriol increased RANKL mRNA and decreased OPG mRNA, whereas these effects were absent in the cells expressing caGα(12) or caRhoA. Basal expression of RANKL and OPG was unaffected by the constructs. The results suggest that Gα(12)-RhoA signaling can inhibit hormone-stimulated osteoclastogenesis by effects on expression of RANKL and OPG. Since PTH can stimulate the Gα(12)-RhoA pathway, the current findings could represent a homeostatic mechanism for regulating osteoclastogenic action.
Collapse
Affiliation(s)
- Jun Wang
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | | |
Collapse
|
14
|
Wang J, Stern PH. Dose-dependent differential effects of risedronate on gene expression in osteoblasts. Biochem Pharmacol 2011; 81:1036-42. [PMID: 21300031 DOI: 10.1016/j.bcp.2011.01.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 01/26/2011] [Accepted: 01/31/2011] [Indexed: 11/18/2022]
Abstract
Bisphosphonates have multiple effects on bone. Their actions on osteoclasts lead to inhibition of bone resorption, at least partially through apoptosis. Effects on osteoblasts vary, with modifications in the molecule and concentration both resulting in qualitatively different responses. To understand the mechanism of the differential effects of high and low bisphosphonate concentrations on osteoblast activity, we compared the effects of 10⁻⁸ M and 10⁻⁴ M risedronate on gene expression in UMR-106 rat osteoblastic cells. Two targeted arrays, an 84-gene signaling array and an 84-gene osteogeneic array were used. Gene expression was measured at 1 and 24 h. Although some genes were regulated similarly by low and high concentrations of the drug, there was also differential regulation. At 1 h, 11 genes (1 signaling and 10 osteogenesis) were solely regulated by the low concentration, and 7 genes (3 signaling, 4 osteogenesis) were solely regulated by the high concentration. At 24 h, 8 genes (3 signaling, 5 osteogenesis) were solely regulated by the low concentration and 30 genes (16 signaling and 14 osteogenesis) were solely regulated by the high concentration. Interestingly, the low, but not the high concentration of risedronate transiently and selectively upregulated several genes associated with cell differentiation. A number of genes related to apoptosis were regulated, and could be involved in effects of bisphosphonates to promote osteoblast apoptosis. Also, observed gene changes associated with decreased angiogenesis and decreased metastasis could, if they occur in other cell types, provide a basis for the effectiveness of bisphosphonates in the prevention of cancer metastases.
Collapse
Affiliation(s)
- J Wang
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine. 303 E. Chicago Ave., Chicago, IL 60611, USA
| | | |
Collapse
|
15
|
Hong Z, Mello A, Yoshida T, Luan L, Stern PH, Rossi A, Ellis DE, Ketterson JB. Hydroxyapatite Coatings Produced by Right Angle Magnetron Sputtering for Biomedical Applications. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-1008-t10-04] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractHydroxyapatite coatings have been widely recognized for their biocompatibility and utility in promoting biointegration of implants in both osseous and soft tissue. Conventional sputtering techniques have shown some advantages over the commercially available plasma spraying method; however, the as-sputtered coatings are usually non-stoichiometric and amorphous which can cause some serious problems such as poor adhesion and excessive coating dissolution rate. A versatile right-angle radio frequency magnetron sputtering (RAMS) approach has been developed to deposit HA coatings on various substrates at low power levels. Using this alternative magnetron geometry, as-sputtered HA coatings are nearly stoichiometric, highly crystalline, and strongly bound to the substrate, as evidenced by analyses using x-ray diffraction (XRD), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). In particular, coatings deposited on oriented substrates show a polycrystalline XRD pattern but with some strongly preferred orientations, indicating that HA crystallization is sensitive to the nature of the substrate. Post deposition heat treatment under high temperature does not result in a marked improvement in the degree of crystallinity of the coatings. To study the biocompatibility of these coatings, murine osteoblast cells were seeded onto various substrates. Cell density counts using fluorescence microscopy show that the best osteoblast proliferation is achieved on an HA RAMS-coated titanium substrate. These experiments demonstrate that RAMS is a promising coating technique for biomedical applications.
Collapse
|
16
|
Hong Z, Mello A, Yoshida T, Luan L, Stern PH, Rossi A, Ellis DE, Ketterson JB. Osteoblast proliferation on hydroxyapatite coated substrates prepared by right angle magnetron sputtering. J Biomed Mater Res A 2010; 93:878-85. [PMID: 19705463 DOI: 10.1002/jbm.a.32556] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The preparation of hydroxyapatite (HA) coatings via a versatile right-angle magnetron sputtering (RAMS) approach for use as a biomaterial has recently been reported. RAMS coatings show some advantages over conventionally sputtered films in that room temperature deposition yields nanocrystalline and nearly stoichiometric HA coatings under appropriate conditions, thereby avoiding the troublesome post deposition annealing treatment. In this article, we present an exploratory study of the biocompatibility of RAMS HA coatings deposited on metallic substrates. RAMS HA coatings with a thickness around 500nm were prepared on various substrates. X-ray diffraction (XRD) analysis showed that the as-deposited HA coatings were polycrystalline with some strongly preferred orientations. Atomic force microscopy (AFM) results showed that the coatings were rather smooth with surface roughness on the order of 10 nm. X-ray photoelectron spectroscopy (XPS) confirmed that the surface chemistry was nearly stoichiometric. To study the biocompatibility of these coatings, murine pre-osteoblastic MC3T3-E1 cells were seeded onto various substrates. Cell density counts using fluorescence microscopy showed that the best osteoblast proliferation is achieved on an HA RAMS-coated titanium substrate. Additionally, in preliminary studies the influence of Zn, Mg, and Al incorporation in the HA crystal lattice on the in vitro behavior was also evaluated. These experiments demonstrate that RAMS is a promising coating technique for biomedical applications.
Collapse
Affiliation(s)
- Zhendong Hong
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA.
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Yoshida T, Flegler A, Kozlov A, Stern PH. Direct inhibitory and indirect stimulatory effects of RAGE ligand S100 on sRANKL-induced osteoclastogenesis. J Cell Biochem 2009; 107:917-25. [DOI: 10.1002/jcb.22192] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
18
|
Kazmers NH, Ma SA, Yoshida T, Stern PH. Rho GTPase signaling and PTH 3-34, but not PTH 1-34, maintain the actin cytoskeleton and antagonize bisphosphonate effects in mouse osteoblastic MC3T3-E1 cells. Bone 2009; 45:52-60. [PMID: 19361585 PMCID: PMC2722510 DOI: 10.1016/j.bone.2009.03.675] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 03/11/2009] [Accepted: 03/25/2009] [Indexed: 11/24/2022]
Abstract
Cytoskeletal elements are critical for cell morphology and signal transduction, and are involved in many cellular processes including motility, intracellular transport, and differentiation. Small GTP-binding proteins (G proteins) of the Ras family, such as RhoA, influence various elements of the cytoskeleton. RhoA stabilizes the actin cytoskeleton and promotes formation of focal adhesions. We found previously that RhoA is expressed in osteoblastic cells and is translocated to the plasma membrane and activated by PTH 1-34 as well as by Nleu(8,18) Tyr(34) PTH 3-34 amide, a PTH analog that does not increase cAMP. We therefore investigated effects of manipulating RhoA on the actin cytoskeleton of osteoblastic MC3T3-E1 cells. Three inhibitors were used: 1) GGTI-2166, a geranylgeranyl transferase I inhibitor that prevents the isoprenylation and membrane translocation of RhoA, 2) Y-27632, a Rho kinase inhibitor, and 3) alendronate, a nitrogen (N)-containing bisphosphonate that reduces intracellular geranylgeranylpyrophosphate through inhibiting farnesyl pyrophosphate synthase. To increase RhoA activity, we used the geranylgeranyl group donor geranylgeraniol (GGOH), and a constitutively active RhoA. The F-actin cytoskeleton and focal adhesions (FA) were visualized with rhodamine-phalloidin and fluorescent anti-vinculin antibodies, respectively. Cells were imaged with confocal microscopy. Actin stress fiber density, edge actin bundle density, focal adhesion density, cellular area and circularity (a morphological descriptor relating area and perimeter) were quantified by a program developed with Matlab software. GGTI-2166, Y-27632, and alendronate reduced actin stress fibers, FA density, and FA size, but had no effect on edge actin bundle density, cellular area, or circularity. GGOH completely antagonized the effects of alendronate, but did not significantly affect responses to GGTI-2166 or Y-27632. Constitutively active RhoA antagonized the effects of alendronate and GGTI-2166, but not those of Y-27632. The effects of alendronate were also antagonized by Nleu(8,18) Tyr(34) PTH 3-34 amide, but not by PTH 1-34. The results indicate that RhoA is involved in the maintenance of stress fibers and focal adhesions in osteoblastic cells, that PTH can affect this pathway independently of cAMP, and that a N-containing bisphosphonate can affect the actin cytoskeleton and focal adhesions through actions on geranylgeranyl groups and potentially through RhoA. In view of the importance of the actin cytoskeleton, the findings constitute evidence that N-containing bisphosphonates, when they attain certain concentrations, have effects on osteoblasts that could influence bone remodeling.
Collapse
Affiliation(s)
- Nikolas H Kazmers
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | | | | | | |
Collapse
|
19
|
Abstract
Prolongation of cell survival through prevention of apoptosis is considered to be a significant factor leading to anabolic responses in bone. The current studies were carried out to determine the role of the small GTPase, RhoA, in osteoblast apoptosis, since RhoA has been found to be critical for cell survival in other tissues. We investigated the effects of inhibitors and activators of RhoA signaling on osteoblast apoptosis. In addition, we assessed the relationship of this pathway to parathyroid hormone (PTH) effects on apoptotic signaling and cell survival. RhoA is activated by geranylgeranylation, which promotes its membrane anchoring. In serum-starved MC3T3-E1 osteoblastic cells, inhibition of geranylgeranylation with geranylgeranyl transferase I inhibitors increased activity of caspase-3, a component step in the apoptosis cascade, and increased cell death. Dominant negative RhoA and Y27632, an inhibitor of the RhoA effector Rho kinase, also increased caspase-3 activity. A geranylgeranyl group donor, geranylgeraniol, antagonized the effect of the geranylgeranyl transferase I inhibitor GGTI-2166, but could not overcome the effect of the Rho kinase inhibitor. PTH 1-34, a potent anti-apoptotic agent, completely antagonized the stimulatory effects of GGTI-2166, dominant negative RhoA, and Y27632, on caspase-3 activity. The results suggest that RhoA signaling is essential for osteoblastic cell survival but that the survival effects of PTH 1-34 are independent of this pathway.
Collapse
Affiliation(s)
- Tomohiko Yoshida
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | | | | |
Collapse
|
20
|
Stern PH. The scoop on dover: a review of The Devil in Dover: An Insider's Story of Dogma v. Darwin in Small‐Town America by LauriLebo (2008), The New Press. FASEB J 2008. [DOI: 10.1096/fj.08-0902ufm] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Paula H. Stern
- Department of Molecular Pharmacology and Biological ChemistryNorthwestern University Chicago Illinois USA
| |
Collapse
|
21
|
Abstract
Antiresorptive agents have proven to be effective therapies for the treatment of bone diseases associated with excessive osteoclast activity. Decreased osteoclast formation, inhibition of osteoclast actions, and reduced osteoclast survival represent mechanisms by which antiresorptive agents could act. The goals of this article are to present the evidence that antiresorptive agents can decrease osteoclast survival through apoptosis, to review the mechanisms by which they are thought to activate the apoptotic process, and to consider whether the actions on apoptosis fully account for the antiresorptive effects. As background, the apoptotic process will be briefly summarized together with the evidence that factors that promote osteoclast survival affect steps in the process. Following this, therapeutic agents that are both antiresorptive and can stimulate osteoclast apoptosis will be discussed. Other bone therapeutic agents that are either antiresorptive or apoptotic, but not both, will be described. Finally, newer antiresorptive compounds that elicit apoptosis and could represent potential therapeutic agents will be noted.
Collapse
Affiliation(s)
- Paula H Stern
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
| |
Collapse
|
22
|
Abstract
New findings reveal that the calcineurin-NFAT signaling pathway helps to promote osteoblast differentiation. Three recent papers reveal somewhat different mechanisms by which this could occur. In one study, transduction of calcineurin Aalpha increased expression of osteoblast differentiation markers, including Runx-2. In another study, NFATc1 cooperatively enhanced Osterix activation of the collagen 1a1 promoter, but did not enhance Runx-2 activity; evidence was provided for the formation of a novel NFATc1-Osterix complex. In a third study, expression of nuclear NFATc1 enhanced Wnt signaling. The observation that the Wnt pathway promotes bone formation is intriguing, because NFATc1 also is critical for osteoclastogenesis. The current findings could be relevant for the osteoporosis seen in patients given the calcineurin inhibitor cyclosporine to prevent transplant rejection, although the results need to be reconciled with aspects of the clinical picture.
Collapse
Affiliation(s)
- Paula H Stern
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611-3072, USA.
| |
Collapse
|
23
|
Abstract
Parathyroid hormone (PTH) and phorbol-12,13-dibutyrate (PDBu) stimulate phospholipase D (PLD) activity and PC hydrolysis in UMR-106 osteoblastic cells {Singh, A.T., Kunnel, J.G., Strieleman, P.J., and Stern, P.H. (1999) Parathyroid Hormone (PTH)-(1-34), [Nle8,18,Tyr34]PTH-(3-34) Amide, PTH-(1-31) Amide, and PTH-Related Peptide-(1-34) Stimulate Phosphatidylcholine Hydrolysis in UMR-106 Osteoblastic Cells: Comparison with Effects of Phorbol 12,13-Dibutyrate, Endocrinology 140, 131-137}. The current studies were designed to determine whether ethanolamine-containing phospholipids, and specifically PE, could also be substrates. In cells labeled with 14C-ethanolamine, PTH and PDBu treatment decreased 14C-PE. In cells co-labeled with 3H-choline and 14C-ethanolamine, PTH and PDBu treatment increased both 3H-choline and 14C-ethanolamine release from the cells. Choline and ethanolamine phospholipid hydrolysis was increased within 5 min, and responses were sustained for at least 60 min. Maximal effects were obtained with 10 nM PTH and 50 nM PDBu. Dominant negative PLD1 and PLD2 constructs inhibited the effects of PTH on the phospholipid hydrolysis. The results suggest that both PC and PE are substrates for phospholipase D in UMR-106 osteoblastic cells and could therefore be sources of phospholipid hydrolysis products for downstream signaling in osteoblasts.
Collapse
Affiliation(s)
- Amareshwar T.K. Singh
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611-3008, U.S.A
| | - Michael A. Frohman
- Department of Pharmacology and the Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, NY 11794-5140, USA
| | - Paula H. Stern
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611-3008, U.S.A
| |
Collapse
|
24
|
Woo JT, Kawatani M, Kato M, Shinki T, Yonezawa T, Kanoh N, Nakagawa H, Takami M, Lee KH, Stern PH, Nagai K, Osada H. Reveromycin A, an agent for osteoporosis, inhibits bone resorption by inducing apoptosis specifically in osteoclasts. Proc Natl Acad Sci U S A 2006; 103:4729-34. [PMID: 16537392 PMCID: PMC1450238 DOI: 10.1073/pnas.0505663103] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mature bone-resorbing osteoclasts (OCs) mediate excessive bone loss seen in several bone disorders, including osteoporosis. Here, we showed that reveromycin A (RM-A), a small natural product with three carboxylic groups in its structure, induced apoptosis specifically in OCs, but not in OC progenitors, nonfunctional osteoclasts, or osteoblasts. RM-A inhibited protein synthesis in OCs by selectively blocking enzymatic activity of isoleucyl-tRNA synthetase. The proapoptotic effect of RM-A was inhibited by neutralization or disruption of the acidic microenvironment, a prominent characteristic of OCs. RM-A was incorporated in OCs but not in nonfunctional osteoclasts and OC progenitors in neutral culture medium. Effects of RM-A on OC apoptosis increased under acidic culture conditions. RM-A not only was incorporated, but also induced apoptosis in OC progenitors in acidic culture medium. RM-A inhibited osteoclastic pit formation, decreased prelabeled (45)Ca release in organ cultures, and antagonized increased bone resorption in ovariectomized mice. These results suggested that preventive effects of RM-A on bone resorption in vitro and in vivo were caused by apoptosis through inhibition of isoleucyl-tRNA synthetase in OCs and that specific sensitivity of OCs to RM-A was due to the acidic microenvironment, which increased cell permeability of RM-A by suppressing dissociation of protons from carboxylic acid moieties, making them less polar. This unique mechanism suggested that RM-A might represent a type of therapeutic agent for treating bone disorders associated with increased bone loss.
Collapse
Affiliation(s)
- Je-Tae Woo
- Department of Biological Chemistry, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Dossing DA, Stern PH. Receptor activator of NF-kappaB ligand protein expression in UMR-106 cells is differentially regulated by parathyroid hormone and calcitriol. J Cell Biochem 2005; 95:1029-41. [PMID: 15849738 DOI: 10.1002/jcb.20470] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Expression of the cytokine, receptor activator of NF-kappaB ligand (RANKL), is stimulated by both parathyroid hormone (PTH) and calcitriol in osteoblasts. Most studies have examined the effects on RANKL mRNA, and less information is available on the protein products. We have determined the effects of PTH, the adenylate cyclase stimulator forskolin, and calcitriol, alone and in combination, on endogenous RANKL protein expression in UMR-106 rat osteoblastic osteosarcoma cells by Western blotting and enzyme immunoassay (EIA). PTH and forskolin dose dependently increased a approximately 52 kDa band in whole cell lysates that was detected by both C- and N-terminal directed RANKL antibodies. Calcitriol treatment produced little or no expression of this approximately 52 kDa band, but markedly increased the expression of a approximately 32 kDa band that was only detected with an antibody directed to the N-terminus of RANKL. An EIA based on RANKL binding to OPG detected a large increase in RANKL expression following calcitriol treatment, and much smaller increases with PTH or forskolin. The combination of PTH and calcitriol or forskolin and calcitriol elicited effects similar to those of PTH and forskolin alone, as detected by both Western blotting and EIA. In contrast to the effects on protein, all agents increased RANKL mRNA expression, with the greatest effects seen with the co-treatments. The results indicate that PTH, likely through effects on cyclic AMP, has a different effect on RANKL processing than calcitriol. The approximately 52 and approximately 32 kDa RANKL products appear to interact differently with OPG, which could affect responses to the agents in target cells.
Collapse
Affiliation(s)
- Debra A Dossing
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | | |
Collapse
|
26
|
Singh ATK, Gilchrist A, Voyno-Yasenetskaya T, Radeff-Huang JM, Stern PH. G alpha12/G alpha13 subunits of heterotrimeric G proteins mediate parathyroid hormone activation of phospholipase D in UMR-106 osteoblastic cells. Endocrinology 2005; 146:2171-5. [PMID: 15705779 DOI: 10.1210/en.2004-1283] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PTH, a major regulator of bone remodeling and a therapeutically effective bone anabolic agent, stimulates several signaling pathways in osteoblastic cells. Our recent studies have revealed that PTH activates phospholipase D (PLD) -mediated phospholipid hydrolysis through a RhoA-dependent mechanism in osteoblastic cells, raising the question of the upstream link to the PTH receptor. In the current study, we investigated the role of heterotrimeric G proteins in mediating PTH-stimulated PLD activity in UMR-106 osteoblastic cells. Transfection with antagonist minigenes coding for small peptide antagonists to G alpha 12 and G alpha13 subunits of heterotrimeric G proteins prevented PTH-stimulated activation of PLD, whereas an antagonist minigene to G alphas failed to produce this effect. Effects of pharmacological inhibitors (protein kinase inhibitor, Clostridium botulinum exoenzyme C3) were consistent with a role of Rho small G proteins, but not of cAMP, in the effect of PTH on PLD. Expression of constitutively active G alpha12 and G alpha13 activated PLD, an effect that was inhibited by dominant-negative RhoA. The results identify G alpha12 and G alpha13 as upstream transducers of PTH effects on PLD, mediated through RhoA in osteoblastic cells.
Collapse
Affiliation(s)
- A T K Singh
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | | | | | | | | |
Collapse
|
27
|
Woo JT, Nakagawa H, Krecic AM, Nagai K, Hamilton AD, Sebti SM, Stern PH. Inhibitory effects of mevastatin and a geranylgeranyl transferase I inhibitor (GGTI-2166) on mononuclear osteoclast formation induced by receptor activator of NF kappa B ligand (RANKL) or tumor necrosis factor-alpha (TNF-alpha). Biochem Pharmacol 2005; 69:87-95. [PMID: 15588717 DOI: 10.1016/j.bcp.2004.08.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Accepted: 08/25/2004] [Indexed: 11/20/2022]
Abstract
We have previously reported that the statin mevastatin (compactin) reversibly inhibits the fusion of TRAP-positive mononuclear preosteoclasts (pOCs) into multinucleated osteoclasts and disrupts the actin ring in mature osteoclasts through the inhibition of protein prenylation. Protein geranylgeranylation, specifically, is known to be required for pOC fusion and for the function and survival of mature osteoclasts. However, it has not been determined whether protein geranylgeranylation is involved in early differentiation of osteoclasts (pOC formation). The current study shows that statins and the geranylgeranyl transferase I inhibitor GGTI-2166 inhibit the pOC formation induced by RANKL or TNF-alpha in cultures of both mouse marrow-derived macrophage-colony-stimulating factor (M-CSF) dependent monocytes (MD cells) and the mouse monocyte cell line RAW 264.7 (RAW cells). Mevastatin, 0.1-0.6 microM, inhibited the formation of pOCs induced by receptor activator of nuclear factor-kappaB ligand (RANKL) or tumor necrosis factor (TNF-alpha) in both cell cultures. The inhibitory effects of mevastatin were overcome by the addition of mevalonate, farnesyl pyrophosphate or geranylgeranyl pyrophosphate. GGTI-2166 inhibited TRAP activity induced by RANKL or TNF-alpha in both cell cultures and prevented the incorporation of [3H]all-trans geranylgeraniol into prenylated proteins in RAW cells. However, the farnesyl transferase inhibitor FTI-2153 did not inhibit TRAP activity although FTI prevented the incorporation of [14C]mevalonate into farnesylated proteins in RAW cells. Clostridium difficile cytotoxin B (toxin B) inhibited pOC formation induced by RANKL or TNF-alpha in both cell cultures. The inhibitory effects of statins and GGTI-2166 on pOC formation may result from the inhibition of the geranylgeranylation of G-proteins, such as Rho or Rac, suggesting that the geranylgeranylation of these proteins is involved in the early differentiation of progenitor cells into pOCs.
Collapse
Affiliation(s)
- Je-Tae Woo
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611, USA
| | | | | | | | | | | | | |
Collapse
|
28
|
Radeff JM, Nagy Z, Stern PH. Rho and Rho kinase are involved in parathyroid hormone-stimulated protein kinase C alpha translocation and IL-6 promoter activity in osteoblastic cells. J Bone Miner Res 2004; 19:1882-91. [PMID: 15476589 DOI: 10.1359/jbmr.040806] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2003] [Revised: 05/19/2004] [Accepted: 06/21/2004] [Indexed: 11/18/2022]
Abstract
UNLABELLED The role of small G-proteins in PTH-stimulated PKC translocation and IL-6 promoter expression in UMR-106 cells was determined. The effects of PTH(1-34) and PTH(3-34) in stimulating PKCalpha translocation and IL-6 were inhibited by agents that interfere with the activity of small G-proteins of the Rho family and with the downstream kinase Rho kinase. INTRODUCTION Activation of protein kinase C (PKC) is a signaling mechanism by which parathyroid hormone (PTH) modulates interleukin-6 (IL-6) in osteoblasts, leading to osteoclastogenesis and bone resorption. PKCalpha and PKCbetaI are translocated after treatment with PTH in UMR-106 osteoblastic cells; however, the pathway leading to PKC isozyme translocation is not established. Diacylglycerol (DAG) generation from phospholipase D (PLD) is one pathway of PKC activation, and PTH-mediated PLD activity is dependent on small G-proteins of the Rho family. This study investigated whether Rho proteins modulate the PKCalpha translocation and IL-6 promoter activity stimulated by PTH in UMR-106 cells. MATERIALS AND METHODS UMR-106 cells were treated with PTH(1-34) or PTH(3-34). PKC translocation was determined by immunofluorescence, Rho A activation by Rhotekin assay and by translocation assessed by Western blotting in membrane and cytosol fractions, and IL-6 promoter expression by luciferase assay. RESULTS AND CONCLUSIONS Inhibition of Rho proteins with Clostridium difficile toxin B or inhibition of Rho prenylation with GGTI attenuated PTH(1-34)- and PTH(3-34)-stimulated translocation of endogenous PKCalpha and IL-6 promoter activity. Expression of a constitutively active RhoA (RhoA63L) mimicked the effect of PTH(1-34) or PTH(3-34) to promote membrane localization of PKCalpha, whereas cells expressing a dominant negative RhoA (RhoA19N) did not respond to PTH(1-34) or PTH(3-34). The Rho kinase inhibitor Y27632 attenuated PTH(1-34)- and PTH(3-34)-stimulated PKCalpha translocation and IL-6 promoter activation. Rho seemed to be acting at a step before production of diacylglycerol (DAG), because the stimulation of PKCalpha translocation by the DAG mimetic phorbol 12,13 dibutyrate (PDBu) was unaffected by C. difficile toxin B or Y27632. These results indicate that Rho proteins are an important component of PTH signaling in osteoblastic cells and provide further demonstration of convergence between PKC and small G-protein signaling pathways.
Collapse
Affiliation(s)
- Julie M Radeff
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | | | | |
Collapse
|
29
|
Stock SR, Ignatiev KI, Foster SA, Forman LA, Stern PH. MicroCT quantification of in vitro bone resorption of neonatal murine calvaria exposed to IL-1 or PTH. J Struct Biol 2004; 147:185-99. [PMID: 15193647 DOI: 10.1016/j.jsb.2004.03.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2003] [Revised: 03/10/2004] [Indexed: 11/17/2022]
Abstract
This study investigated how effectively a laboratory microCT (X-ray micro-computed tomography) system can quantify bone resorption in an in vitro calvarial model and how well this measure correlates with a conventional assay for calcium release (fluorometric titration). In vitro bone resorption in neonatal murine calvaria was quantified for 0.3 or 1.0 nM interleukin-1 (IL-1) or for 1.0 or 10.0 nM parathyroid hormone (PTH) treatment. Compared to control calvaria, a significantly greater fraction F of the calvarial "shell" (computed from the volumetric microCT data) was resorbed in treated calvaria of 5- to 7-day-old pups from the same litter. Excellent correlation (R2 = 0.8234) was observed between F and calcium release, and, unlike the calcium assay, the 3-D maps revealed where bone was resorbed. Mineral was preferentially lost near the sutures, and areas away from the suture were left relatively intact. MicroCT of calvaria before and after 96 h culture demonstrated that this X-irradiation neither increased control resorption nor prevented responses in the treated calvaria. Observations on calvaria from intact mice aged 1, 3, 5, 8, and 11 days showed uniformly distributed mineral (not a pronounced patchwork of "high" and "low" mineral regions) and increasing levels of mineral with age; this suggested that the spatial patterns of resorption were not related to inhomogeneities in the starting mineral distribution.
Collapse
Affiliation(s)
- S R Stock
- Institute for Bioengineering and Nanoscience in Advanced Medicine, Northwestern University, Chicago, IL, USA.
| | | | | | | | | |
Collapse
|
30
|
Igarashi K, Hirotani H, Woo JT, Stern PH. Cyclosporine A and FK506 induce osteoclast apoptosis in mouse bone marrow cell cultures. Bone 2004; 35:47-56. [PMID: 15207740 DOI: 10.1016/j.bone.2004.02.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Revised: 01/14/2004] [Accepted: 02/03/2004] [Indexed: 11/26/2022]
Abstract
Studies were carried out to characterize the effects of cyclosporines and FK506 on the formation and survival of osteoclasts deriving from mouse bone marrow cultures. Cyclosporin A (CsA), cyclosporin B (CsB), cyclosporin H (CsH), and FK506 all inhibited receptor activator of NFkappaB ligand (RANKL)-stimulated tartrate-resistant acid phosphatase (TRAP) activity and generation of TRAP+ multinucleated cells in the cultures. CsA and CsG were approximately equipotent, CsH was approximately one order of magnitude less potent than the other cyclosporines, and FK506 was approximately two orders of magnitude more potent than CsA and CsG. All of the inhibitors demonstrated greater potency and efficacy on decreasing the number of TRAP+ multinucleated cells than on decreasing total TRAP activity. Further evidence that late stages were more sensitive to inhibition was obtained in experiments in which CsA was present for different segments of the RANKL-stimulated culture period. CsA was as efficacious when added for the final 2 days of a 4-day culture as when added for the entire culture period, whereas it was less effective if added for only the first 2 days of the culture. When CsA or FK506 were added for 1 day to cultures in which osteoclasts had already formed, the numbers of TRAP+ osteoclasts decreased. Treatment with CsA or FK506 produced nuclear fragmentation and disruption of the multinucleated osteoclasts and an increase in caspase-3 activity. The apoptosis inhibitor z-VAD partially prevented the inhibitory effects of CsA and FK506 on the survival of TRAP+ multinucleated cells in the cultures and also preserved the normal osteoclast morphology. The data indicate that an important component of the inhibitory effects of CsA and FK506 on marrow-derived osteoclasts is the induction of apoptosis.
Collapse
Affiliation(s)
- K Igarashi
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | | | | | | |
Collapse
|
31
|
Hirotani H, Tuohy NA, Woo JT, Stern PH, Clipstone NA. The calcineurin/nuclear factor of activated T cells signaling pathway regulates osteoclastogenesis in RAW264.7 cells. J Biol Chem 2004; 279:13984-92. [PMID: 14722106 DOI: 10.1074/jbc.m213067200] [Citation(s) in RCA: 205] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Although best known for its role in T lymphocyte activation, the calcineurin/nuclear factor of activated T cells (NFAT) signaling pathway is also known to be involved in a wide range of other biological responses in a variety of different cell types. Here we have investigated the role of the calcineurin/NFAT signaling pathway in the regulation of osteoclast differentiation. Osteoclasts are bone-resorbing multinucleated cells that are derived from the monocyte/macrophage cell lineage after stimulation with a member of the tumor necrosis factor family of ligands known as receptor activator of nuclear factor-kappaB ligand (RANKL). We now report that inhibition of calcineurin with either the immunosuppressant drugs cyclosporin A and FK506, or the retrovirally mediated ectopic expression of a specific calcineurin inhibitory peptide, all potently inhibit the RANKL-induced differentiation of the RAW264.7 monocyte/macrophage cell line into mature multinucleated osteoclasts. In addition, we find that NFAT family members are expressed in RAW264.7 cells and that their expression is up-regulated in response to RANKL stimulation. Most importantly, we find that ectopic expression of a constitutively active, calcineurin-independent NFATc1 mutant in RAW264.7 cells is sufficient to induce these cells to express an osteoclast-specific pattern of gene expression and differentiate into morphologically distinct, multinucleated osteoclasts capable of inducing the resorption of a physiological mineralized matrix substrate. Taken together, these data define calcineurin as an essential downstream effector of the RANKL-induced signal transduction pathway leading toward the induction of osteoclast differentiation and furthermore, indicate that the activation of the NFATc1 transcription factor is sufficient to initiate a genetic program that results in the specification of the mature functional osteoclast cell phenotype.
Collapse
Affiliation(s)
- Hiroaki Hirotani
- Department of Molecular Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | | | | | | | | |
Collapse
|
32
|
Abstract
Mechanical stimulation is essential for maintaining the homeostasis and architecture of connective tissues including bone. The purpose of our study was to test the importance of several potential signaling intermediates in the anabolic responses of bone to loads applied with a newly developed micromechanical loading device. Tibial bones excised from 7- to 8-day-old CD-1 mice were cyclically loaded at 1 Hz, 1000 muepsilon (microstrain) at a peak load of 100 mN. DNA and protein synthesis were evaluated by measuring the incorporation of 3H-thymidine and 14C-proline, respectively. The roles of cyclooxygenase (COX) isoforms, nitric oxide synthase (NOS) isoforms, and glutamate receptor-gated Ca2+ channeling were examined by incubating the bones in the presence of each of their specific inhibitors. The results indicate that COX-2 and constitutive NOS are important signaling molecules in the anabolic responses of neonatal tibial bone to the micromechanical load in vitro.
Collapse
Affiliation(s)
- J G Kunnel
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611-3008, USA
| | | | | | | |
Collapse
|
33
|
Radeff JM, Singh ATK, Stern PH. Role of protein kinase A, phospholipase C and phospholipase D in parathyroid hormone receptor regulation of protein kinase Cα and interleukin-6 in UMR-106 osteoblastic cells. Cell Signal 2004; 16:105-14. [PMID: 14607281 DOI: 10.1016/s0898-6568(03)00131-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Parathyroid hormone (PTH) stimulates both bone formation and resorption by activating diverse osteoblast signalling pathways. Upstream signalling for PTH stimulation of protein kinase C-alpha (PKCalpha) membrane translocation and subsequent expression of the pro-resorptive cytokine interleukin-6 (IL-6) was investigated in UMR-106 osteoblastic cells. PTH 1-34, PTH 3-34, PTHrP and PTH 1-31 stimulated PKCalpha translocation and IL-6 promoter activity. Pharmacologic intervention at the adenylyl cyclase (AC) pathway (forskolin, IBMX, PKI) failed to alter PTH 1-34- or PTH 3-34-stimulated PKCalpha translocation. The phosphoinositol-phospholipase C (PI-PLC) antagonist U73122 slightly decreased PTH 1-34-stimulated PKCalpha translocation; however, the control analogue U73343 acted similarly. Propranolol, an inhibitor of phosphatidic acid (PA) phosphohydrolase, decreased diacylglycerol (DAG) formation and attenuated PTH 1-34- and PTH 3-34-stimulated PKCalpha translocation and IL-6 promoter activity, suggesting a phospholipase D (PLD)-dependent mechanism. This is the first demonstration that PLD-mediated signalling leads to both PKC-alpha translocation and IL-6 promoter activation in osteoblastic cells.
Collapse
Affiliation(s)
- Julie M Radeff
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | | | | |
Collapse
|
34
|
Bhattacharyya RS, Stern PH. IGF-I and MAP kinase involvement in the stimulatory effects of LNCaP prostate cancer cell conditioned media on cell proliferation and protein synthesis in MC3T3-E1 osteoblastic cells. J Cell Biochem 2003; 90:925-37. [PMID: 14624452 DOI: 10.1002/jcb.10726] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bone metastases from prostate cancer cause abnormal new bone formation, however, the factors involved and the pathways leading to the response are incompletely defined. We investigated the mechanisms of osteoblast stimulatory effects of LNCaP prostate carcinoma cell conditioned media (CM). MC3T3-E1 osteoblastic cells were cultured with CM from confluent LNCaP cells. LNCaP CM stimulated MAP kinase, cell proliferation (3H-thymidine incorporation), and protein synthesis (14C-proline incorporation) in the MC3T3-E1 cells. The increases in cell proliferation and protein synthesis were prevented by inhibition of the MAP kinase pathway. IGF-I mimicked the effects of the CM on the MC3T3-E1 cells and inhibition of IGF-I action decreased the LNCaP CM stimulation of 3H-thymidine and 14C-proline incorporation and MAP kinase activity. The findings indicate that IGF-I is an important factor for the stimulatory effects of LNCaP cell CM on cell proliferation and protein synthesis in osteoblastic cells, and that MAP kinase is a component of the signaling pathway for these effects.
Collapse
Affiliation(s)
- Rumi S Bhattacharyya
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | | |
Collapse
|
35
|
Singh ATK, Bhattacharyya RS, Radeff JM, Stern PH. Regulation of parathyroid hormone-stimulated phospholipase D in UMR-106 cells by calcium, MAP kinase, and small G proteins. J Bone Miner Res 2003; 18:1453-60. [PMID: 12929934 DOI: 10.1359/jbmr.2003.18.8.1453] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED Signaling intermediates for PTH and phorbol activation of PLD in UMR-106 cells were determined. Calcium was required, and the effects of PTH, phorbol, and calcium were dependent on p42/44 MAP kinase and small G proteins, specifically RhoA, acting through Rho kinase. INTRODUCTION Phospholipase D (PLD) plays a key signaling role in numerous cellular processes. PLD-stimulated hydrolysis of phosphatidylcholine (PC) generates phosphatidic acid, a source of diacylglycerol (DAG). We previously reported that parathyroid hormone (PTH) stimulates PLD activity in UMR-106 osteoblastic cells by a protein kinase C (PKC)-independent mechanism. The current study investigated the roles of calcium, MAP kinase, and small G proteins in PTH- and phorbol-12,13-dibutyrate (PDBu)-stimulated transphosphatidylation of ethanol, a reaction catalyzed by PLD. METHODS UMR-106 cells were labeled with 3H-palmitic and treated in the presence of ethanol. Phosphatidylethanol was separated by thin-layer chromatography and detected by autoradiography, and the bands were scraped and counted. Statistical significance of the responses from three to nine replicates was determined by ANOVA and Tukey's post-test. RESULTS AND CONCLUSIONS PTH and PDBu effects were attenuated by EGTA, BAPTA, nifedipine, and dantrolene, whereas ionomycin or 2X calcium increased basal PLD activity. PTH activated p42/p44 MAP kinase, and the effects of PTH, PDBu, and ionomycin on PLD, but not on calcium influx, were prevented by the MEK inhibitors PD98059 and U0126. Small G proteins were shown to be involved in the effects of PTH, PDBu, and ionomycin on PLD. Inhibition of ARF by brefeldin prevented the PLD activation by all three agonists. A nonselective Rho/Rac/cdc-42 inhibitor, Clostridium difficile toxin B, also inhibited the effects of all three agonists on PLD. More selective inhibition of RhoA with a dominant negative RhoA construct or by inhibiting geranylgeranyltransferase I antagonized the effects of PTH, PDBu, and ionomycin, as did inhibiting the downstream kinase, Rho kinase. The current results reveal the importance of calcium, MAP kinase, and small G proteins in PTH and PDBu stimulation of PLD activity in UMR-106 cells.
Collapse
Affiliation(s)
- Amareshwar T K Singh
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611-3008, USA
| | | | | | | |
Collapse
|
36
|
Kunnel JG, Gilbert JL, Stern PH. In vitro mechanical and cellular responses of neonatal mouse bones to loading using a novel micromechanical-testing device. Calcif Tissue Int 2002; 71:499-507. [PMID: 12232683 DOI: 10.1007/s00223-001-1073-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2002] [Indexed: 10/27/2022]
Abstract
Mechanical stimulation is critical for the maintenance of bone architecture and bone mass. These effects are dependent on the magnitude, duration, and rate of the mechanical stimuli. The goals of the present study were to develop and optimize a micromechanical-testing device for in vitro mechanical stimulation of whole viable bones, and to identify the physical parameters of loading that elicit maximal anabolic responses. The model was the 7-8-day-old neonatal CD-1 mouse tibia. A range of cyclic strain magnitudes [500-7000 microstrain (microstrain)] and frequencies [0.2-30 hertz (Hz)] were applied to the neonatal bones. Incremental cyclic compression tests showed that the bones were nonlinearly viscoelastic. Bone stiffness and hysteresis energy dissipation were dependent on the maximum load magnitude. DNA and protein synthesis were significantly enhanced in bones that were cyclically loaded at 0.5 Hz/1000 microstrain, 0.5 Hz/2000 microstrain, or l Hz/1000 microstrain, compared to nonloaded controls. Anabolic responses were maximal at a peak load of 100 mN at l Hz/1000 microstrain. Autoradiography of the bones loaded under these conditions showed proliferation of cells at periosteal surfaces. Hysteresis energy per cycle was greatest at loads that caused the largest anabolic responses. The parameters of strain and load that elicit optimal effects on the neonatal bones are comparable to those in other systems, validating the use of the instrumentation for studying the mechanisms of the anabolic responses. The findings also suggest that hysteresis energy per cycle may be a determinant of the anabolic response of bones to mechanical stimulation.
Collapse
Affiliation(s)
- J G Kunnel
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL 60611-3008, USA
| | | | | |
Collapse
|
37
|
Abstract
The effects of an important new anti-inflammatory agent, the selective cyclooxygenase-2 inhibitor celecoxib, on bone resorption and osteoclastogenesis elicited by the inflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), the endotoxin lipopolysaccharide (LPS), and the systemic hormones 1alpha,25-dihydroxyvitamin D(3) and parathyroid hormone were examined in vitro. Bone resorption was evaluated by measuring calcium released into the culture medium in a neonatal mouse calvarial bone organ culture. Osteoclastogenesis was evaluated by measuring tartrate-resistant acid phosphatase activity in the cells in cocultures of bone marrow cells and osteoblastic cells and in macrophage-colony-stimulating factor-dependent bone marrow cell cultures. Celecoxib (0.1 microM) completely inhibited the calcium release induced by IL-1beta, TNF-alpha, and LPS. The resorptive effect of 1alpha,25-dihydroxyvitamin D(3) was inhibited partially by celecoxib. In contrast, celecoxib did not inhibit the calcium release elicited by parathyroid hormone or prostaglandin E(2). Celecoxib (0.1 microM) also markedly inhibited osteoclastogenesis induced by these stimulators of bone resorption except for PGE(2) in the coculture system, whereas it failed to inhibit osteoclastogenesis in macrophage-colony-stimulating factor-dependent bone marrow cell cultures. These results indicate that, under certain conditions, cyclooxygenase-2-dependent prostaglandin synthesis is critical for the bone resorption induced by IL-1beta, TNF-alpha, and LPS, and for the osteoclastogenesis induced by these pro-inflammatory molecules and calciotropic hormones. The prevention of prostaglandin synthesis by inflammatory cytokines in bone cells could contribute to the efficacy of celecoxib in preventing bone loss in rheumatoid arthritis.
Collapse
Affiliation(s)
- Kaoru Igarashi
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL 60611, USA
| | | | | |
Collapse
|
38
|
Abstract
Studies with antagonists have provided evidence that protein kinase C (PKC) is involved in several of the actions of parathyroid hormone (PTH) on bone. PTH increases total PKC activity in bone and bone cells. The current studies investigated whether PTH can activate specific PKC isozymes, as demonstrated by translocation of these isozymes from cytosolic to membrane fractions. The isozymes selected for study, alpha, betaI, delta, epsilon, and zeta, were shown previously by us to be present in normal osteoblasts and several osteosarcoma-derived osteoblastic cells. UMR-106 cells, a widely used osteoblastic cell line, were selected for the current study. PKC isozymes in whole cell lysates and cell fractions were visualized by western blotting; isozyme distribution was also visualized by immunofluorescence. The total amounts of the isozymes and their relative distribution between membrane and cytosolic fractions in untreated cells were stable over a range of passages (5-20 from initial plating). In untreated cells, the concentrations of PKC alpha, betaI, and zeta were higher in the cytosol, and PKC delta and epsilon were higher in the membrane fraction. Treatment with 1 or 10 nmol/L PTH for 1 or 5 min stimulated translocation of PKC alpha and betaI, with variable effects on the other isozymes. Treatment with phorbol-12,13-dibutyrate (PDBu), 1 micromol/L for 5 min, elicited similar effects to those of PTH on PKC alpha and betaI. Treatment with PDBu for 48 h resulted in a downregulation of PKC alpha, whereas a 48 h treatment with PTH did not cause downregulation. The results indicate that PTH can affect specific PKC isozymes, providing a mechanism for differential regulation of cellular actions through this pathway.
Collapse
Affiliation(s)
- D A Dossing
- Department of Molecular Pharmacology, Northwestern University Medical School, Chicago, IL 60611, USA
| | | | | | | | | | | |
Collapse
|
39
|
Radeff JM, Nagy Z, Stern PH. Involvement of PKC-beta in PTH, TNF-alpha, and IL-1 beta effects on IL-6 promoter in osteoblastic cells and on PTH-stimulated bone resorption. Exp Cell Res 2001; 268:179-88. [PMID: 11478844 DOI: 10.1006/excr.2001.5283] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Protein kinase C (PKC) has been shown to be activated by parathyroid hormone (PTH) in osteoblasts. Prior evidence suggests that this activation mediates responses leading to bone resorption, including production of the osteoclastogenic cytokine interleukin-6 (IL-6). However, the importance of specific PKC isozymes in this process has not been investigated. A selective antagonist of PKC-beta, LY379196, was used to determine the role of the PKC-beta isozyme in the expression of IL-6 in UMR-106 rat osteoblastic cells and in bone resorption in fetal rat limb bone organ cultures. PTH, tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 beta (IL-1 beta) induced translocation of PKC-alpha and -beta(I) to the plasma membrane in UMR-106 cells within 5 min. The stimulation of PKC-beta(I) translocation by PTH, TNF-alpha or IL-1 beta was inhibited by LY379196. In contrast, LY379196 did not affect PTH, TNF-alpha-, or IL-1 beta-stimulated translocation of PKC-alpha. PTH, TNF-alpha, and IL-1 beta increased luciferase expression in UMR-106 cells transiently transfected with a -224/+11 bp IL-6 promoter-driven reporter construct. The IL-6 responses were also attenuated by treatment with LY379196. Furthermore, LY379196 inhibited bone resorption elicited by PTH in fetal rat bone organ cultures. These results indicate that PKC-beta(I) is a component of the signaling pathway that mediates PTH-, TNF-alpha-, and IL-1 beta-stimulated IL-6 expression and PTH-stimulated bone resorption.
Collapse
Affiliation(s)
- J M Radeff
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | | | | |
Collapse
|
40
|
Nagy Z, Radeff J, Stern PH. Stimulation of interleukin-6 promoter by parathyroid hormone, tumor necrosis factor alpha, and interleukin-1beta in UMR-106 osteoblastic cells is inhibited by protein kinase C antagonists. J Bone Miner Res 2001; 16:1220-7. [PMID: 11450697 DOI: 10.1359/jbmr.2001.16.7.1220] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
To investigate the level at which protein kinase C (PKC) regulates expression of interleukin-6 (IL-6) in osteoblastic cells, effects of several PKC antagonists and PKC down-regulation by phorbol ester were studied in UMR-106 osteoblastic cells that had been transiently transfected with a -224/+11-base pair (bp) IL-6 promoter coupled to a luciferase reporter. Parathyroid hormone (PTH) elicited a dose-dependent stimulation of the IL-6 promoter expression, with significant increases produced by 5 h of treatment with concentrations of PTH as low as 10(-14) M. The increase in IL-6 promoter expression was inhibited by the PKC antagonists GF109203X, 30 nM to 1 microM, and calphostin C, 250 nM. Prior down-regulation of PKC with 100 nM phorbol-12,13-dibutyrate (PDBU) for 48 h inhibited the PTH effect as well as the smaller stimulatory effects elicited by tumor necrosis factor alpha (TNF-alpha), 10(-9)-10(-8) M, and by IL-1beta, 1-10 ng/ml. In contrast to these findings, the stimulatory effects of PTH, TNF-alpha, and IL-1beta on the IL-6 promoter expression were enhanced by staurosporine. Treatment with GF109203X or down-regulation of PKC with PDBU prevented the stimulatory effects of staurosporine. PKC activity was increased by staurosporine. The findings with staurosporine are consistent with our earlier observations that this agent enhances the calcium signaling and bone resorption elicited by PTH. The studies support the role of PKC in the stimulatory effects of PTH, TNF-alpha, and IL-1beta on IL-6 expression.
Collapse
Affiliation(s)
- Z Nagy
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | | | | |
Collapse
|
41
|
Abstract
PTH and thyroid hormone (T(3)) stimulate anabolic and catabolic processes in bone predominantly by acting on osteoblasts. Both inadequate and excessive secretion of either hormone can result in clinical bone disorders. In addition, T(3) and PTH related peptide (PTHrP) have multiple effects on a wide number of other tissues modulating both cell differentiation and proliferation. To address the question of whether there might be functional mutual regulation of T(3) receptors (TR) and PTH/PTHrP receptors (PTHR), we studied their expression and receptor-mediated intracellular effects in rat osteoblastic osteosarcoma (ROS) 17/2.8 cells. PTHR were up-regulated by T(3) pretreatment (10(-)(10)-10(-)(6) M) in ROS 17/2.8 cells in a dose-dependent manner. T(3) pretreatment increased both PTH-induced cyclic AMP response element binding protein (CREB) phosphorylation and PTH-induced intracellular calcium transients, and further decreased PTH-induced down-regulation of alkaline phosphatase activity, suggesting that there are functional consequences of the PTHR up- regulation. Pretreatment with PTH (10(-)(10)-10(-)(6) M) or PTHrP (10(-)(9) M) for 3-4 days resulted in a dose-dependent up-regulation of TR in ROS 17/2.8 cells. cAMP analogues or a calcium ionophore were able to mimic the effect of PTH on TR binding, suggesting that either the cAMP-signaling pathway or Ca(2+) could be involved in PTH-induced up-regulation of the TR. These observations provide a novel example of mutual interactions between nuclear receptors and membrane receptors and may have significant implications for the regulation of bone remodeling in health and disease.
Collapse
Affiliation(s)
- W X Gu
- Department of Molecular Pharmacology and Biological Chemistry,, Northwestern University Medical School, Chicago, Illinois 60611-3008, USA
| | | | | | | |
Collapse
|
42
|
Abstract
Activation of protein kinase C (PKC) has been suggested to play a role in bone resorption. However, phorbol esters, which activate PKC, have been reported to have both stimulatory and inhibitory effects on bone resorption. To study the role of PKC in bone resorption further, we have measured calcium release elicited by bone-resorbing hormones from isolated bones incubated with the PKC inhibitors staurosporine (ST) and the more PKC-selective ST analog bisindolylmaleimide I (GF109203X; GF). In fetal rat limb bone organ cultures, ST (1 microM) or GF (1 microM) significantly reduced the bone resorption induced by maximal concentrations of parathyroid hormone (PTH). However, when submaximal concentrations of PTH were used, lower concentrations of the two antagonists had divergent effects. GF (20-300 nM) acted solely as an antagonist, whereas ST (10-100 nM) significantly enhanced resorptive responses to PTH. ST also enhanced the bone resorption elicited by alpha-thrombin, tumor necrosis factor-alpha (TNF-alpha), and thyroxin (T4). ST alone had small stimulatory effects in some experiments. GF prevented the stimulatory effects of ST alone as well as the enhancing effect of ST on PTH-stimulated resorption. The divergent effects of ST and GF on the responses of bone to low concentrations of PTH and the ability of GF to antagonize the stimulatory effects of ST suggest that PKC isozymes have complex and even antagonistic effects on bone resorption.
Collapse
Affiliation(s)
- S K Lee
- Catholic Research Institutes of Medical Science, The Catholic University, Seoul, South Korea
| | | |
Collapse
|
43
|
Singh AT, Radeff JM, Kunnel JG, Stern PH. Phosphatidylcholine-specific phospholipase C inhibitor, tricyclodecan-9-yl xanthogenate (D609), increases phospholipase D-mediated phosphatidylcholine hydrolysis in UMR-106 osteoblastic osteosarcoma cells. Biochim Biophys Acta 2000; 1487:201-8. [PMID: 11018472 DOI: 10.1016/s1388-1981(00)00096-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Our previous studies have shown that parathyroid hormone (PTH) stimulates phosphatidylcholine (PC) hydrolysis by phospholipase D (PLD) and transphosphatidylation in UMR-106 osteoblastic cells. To determine whether phospholipase C (PLC) is also involved in the PTH-mediated PC hydrolysis, we used the inhibitor, tricyclodecan-9-yl xanthogenate (D609), a putatively selective antagonist of this pathway. Consistent with this proposed mechanism, D609 decreased (3)H-phosphocholine in extracts from UMR-106 cells prelabeled with (3)H-choline. Unexpectedly, D609 enhanced PC hydrolysis and transphosphatidylation, suggesting that either there was a compensatory increase in PLD activity when PLC was inhibited, or that D609 directly increased PLD activity. The D609-stimulated increase in PC hydrolysis was rapid, being seen as early as 2 min. The effect of D609 was temperature-sensitive, consistent with an enzymatic mechanism. The D609-stimulated increase in PC hydrolysis was PKC-independent, based upon the lack of effect of down-regulation of PKC by phorbol 12,13-dibutyrate on the response. The studies reveal a novel action of this inhibitor on signaling in osteoblastic cells which might influence downstream responses.
Collapse
Affiliation(s)
- A T Singh
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL 60611-3008, USA.
| | | | | | | |
Collapse
|
44
|
Semler DE, Morris DL, Stern PH. Endothelin-stimulated Ca(2+)signaling and endothelin receptor expression are decreased by parathyroid hormone treatment in UMR-106 osteoblastic osteosarcoma cells. Cell Calcium 2000; 28:55-64. [PMID: 10942704 DOI: 10.1054/ceca.2000.0129] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Modulation of endothelin (ET-1)-induced [Ca(2+)](i)transients and receptor expression by parathyroid hormone (PTH) was studied in UMR-106 osteoblastic osteosarcoma cells. Ca(2+)signaling was assessed with Fura-2, and ET receptor mRNA expression was determined using ET(A)- and ET(B)-specific primers and RT-PCR amplification. ET-1 binding in UMR-106 cell membranes was also measured. PTH pretreatment for 8 h decreased the [Ca(2+)](i)transients elicited by ET-1 and by the ET(B)-selective agonist sarafotoxin 6c (S6c). When ET(B)receptors were desensitized by pretreatment with S6c or blocked with the ET(B)-selective antagonist BQ-788, the remaining ET(A)component of the signal was also decreased by PTH pretreatment. In contrast, [Ca(2+)](i)transients elicited by PGF(2alpha)and ionomycin were increased following PTH pretreatment, indicating that the effect of PTH to decrease ET-1-stimulated transients was selective. PTH pretreatment also decreased [(125)I]ET-1 binding and ET(A)and ET(B)mRNA, with maximal effects at approximately 8 h. ET-1 was not detectable in medium from either control or PTH treated UMR-106 cultures, suggesting that the decreased expression of ET receptors was not due to enhanced ET production and subsequent homologous desensitization. The downregulation of ET receptors in osteoblasts by PTH pretreatment may serve as a homeostatic mechanism in bone.
Collapse
Affiliation(s)
- D E Semler
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL 60611, USA
| | | | | |
Collapse
|
45
|
Lakatos P, Foldes J, Nagy Z, Takacs I, Speer G, Horvath C, Mohan S, Baylink DJ, Stern PH. Serum insulin-like growth factor-I, insulin-like growth factor binding proteins, and bone mineral content in hyperthyroidism. Thyroid 2000; 10:417-23. [PMID: 10884189 DOI: 10.1089/thy.2000.10.417] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The mechanism by which thyroid hormones promote bone growth has not yet been elucidated. In vitro, thyroid hormones stimulate insulin-like growth factor-I (IGF-I) production by osteoblasts, which is important for the anabolic effects of the hormone on bone. To determine whether the IGF-I/IGF binding protein (IGFBP) profile is affected when thyroid hormone production is altered in vivo, we studied 36 women who had recently been diagnosed with hyperthyroidism (age: 29-67 years; 19 with Graves' disease, 17 with toxic nodular goiter) and 36 age-matched healthy women as controls. Serum IGF-I, and its binding proteins (IGFBP-3, IGFBP-4, and IGFBP-5), as well as bone mineral density (BMD) at the lumbar spine, femoral neck, and radius midshaft were measured before and 1 year after antithyroid (methimazole) treatment. Serum IGF-I levels were significantly increased in the hyperthyroid patients before treatment (214 +/- 18.2 ng/mL vs. 145 +/- 21.3 ng/mL; p < 0.05). There was no difference in IGF-I levels of patients with Graves' disease and toxic nodular goiter. Serum IGF-I concentrations returned to normal after treatment with methimazole. Serum IGFBP-3 and IGFBP-4 values were significantly elevated in the hyperthyroid group before treatment (3960 +/- 220 ng/mL and 749.7 +/- 53.1 ng/mL vs. 2701 +/- 180 ng/mL and 489.9 +/- 32.4 ng/mL; p < 0.05 and p < 0.01, respectively) and were reduced to those of controls after treatment. Serum IGFBP-5 of hyperthyroid subjects was not different from that of controls either before or after therapy. Serum free thyroxine showed a positive correlation with serum levels of IGF-I (r = 0.73, p < 0.05), IGFBP-3 (r = 0.59, p < 0.05), and IGFBP-4 (r = 0.67, p < 0.05) but not IGFBP-5. BMD at the radius midshaft was significantly lower in hyperthyroid patients at the start of the study and showed a positive correlation with serum IGF-I (r = 0.58; p < 0.001) and a negative correlation with IGFBP-4 (r = -0.61; p < 0.05). Radius BMD showed a 7.2% increase in the hyperthyroid group after 1 year of methimazole treatment, and the correlation between BMD and serum IGF-I disappeared. Our data indicate that thyroid hormones may influence the IGF-I/IGFBP system in vivo in hyperthyroidism. The anabolic effects of increased levels of IGF-I may be limited in hyperthyroidism due to the increases of inhibitory IGFBPs that can counteract the anabolic effects and contribute to the observed net bone loss.
Collapse
Affiliation(s)
- P Lakatos
- 1st Department of Medicine, Semmelweis University Medical School, Budapest, Hungary.
| | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Abstract
The cytokine interleukin-6 (IL-6) is increased in bone and bone cells by several resorptive stimuli, including parathyroid hormone (PTH), IL-1beta, and tumor necrosis factor-alpha (TNF-alpha). The current studies were designed to determine the contribution of the protein kinase C (PKC) signaling pathway to the effects of these three agents to increase IL-6 in UMR-106 rat osteoblastic cells. Cells were pretreated with vehicle (dimethylsulfoxide [DMSO]) or the phorbol ester, phorbol 12,13-dibutyrate (PDB; 300 nM) for 48 h to down-regulate phorbol-sensitive PKC isozymes. Either PTH (0.1-10 nM), IL-1beta (0.1-10 nM), or TNF-alpha (5 nM and 10 nM) was then added for 24 h in the continued presence of vehicle or PDB. PKC isozymes were visualized by Western immunoblotting and IL-6 was determined by bioassay. PDB pretreatment caused a partial down-regulation of the conventional alpha-PKC and betaI-PKC isozymes and complete down-regulation of the novel delta-isoenzyme and epsilon-isozymes but it had no effect on the atypical zeta-PKC isozyme. PDB pretreatment reduced IL-6 responses to 5 nM and 10 nM PTH by 61% and 33%, respectively, reduced IL-6 responses to 5nM and 10 nM TNF-a by 54% and 42%, respectively, and failed to inhibit the IL-6 responses to 0.1-10 nM IL-1beta. The PDB pretreatment protocol significantly enhanced PTH-stimulated cyclic adenosine monophosphate (cAMP) production. The PKC inhibitor calphostin C also decreased IL-6 responses to PTH. Thus, in this osteoblast cell line, the PKC pathway is an important component of the signaling pathway for the IL-6 production stimulated by PTH and TNF-alpha but not that from IL-1beta.
Collapse
Affiliation(s)
- J L Sanders
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | | |
Collapse
|
47
|
Woo JT, Kasai S, Stern PH, Nagai K. Compactin suppresses bone resorption by inhibiting the fusion of prefusion osteoclasts and disrupting the actin ring in osteoclasts. J Bone Miner Res 2000; 15:650-62. [PMID: 10780857 DOI: 10.1359/jbmr.2000.15.4.650] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Compactin (mevastatin), which inhibits 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, and thus biosynthesis of cholesterol and the prenylation of proteins, inhibits osteoclastic bone resorption. Although it has been suggested that compactin inhibits bone resorption by inducing apoptosis of osteoclasts, the pathway by which compactin inhibits resorption has not been established. We investigated the effect of compactin on the differentiation of osteoclasts and the relationship between the morphological changes elicited by compactin and its inhibitory effect on bone resorption. Compactin inhibited the differentiation of osteoclasts, interfering with the fusion process by which prefusion osteoclasts (pOCs) develop into multinucleated osteoclast-like cells (OCLs), and also disrupted the actin ring of OCLs. The potency of compactin to inhibit fusion of pOCs and to disrupt the actin ring of OCLs corresponded to that of compactin to inhibit bone resorption. The effects of compactin were prevented by the addition of MVA lactone or its downstream products farnesylpyrophosphate (FPP) and geranylgeranyl-pyrophosphate (GGPP) but not by squalene. Apoptosis of OCLs was not induced by the concentration of compactin that inhibited fusion of pOCs and disrupted the actin ring. The normal process of pOC fusion and the integrity of the actin ring were restored by the withdrawal of compactin from the cultures after they had been treated with compactin for 24 h, but they were not restored by the addition of zVAD-fmk, a caspase inhibitor. Compactin also reversibly inhibited interleukin-1beta (IL-1beta)-, 1alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3)-, and parathyroid hormone (PTH)-stimulated 45Ca release in bone organ cultures. Our results indicate that the inhibitory effects of compactin on bone resorption result from the inhibition of fusion of pOCs into OCLs and disruption of actin ring in OCLs and that apoptosis of OCLs is not necessary for these inhibitory effects of compactin. These effects of compactin are likely to be a consequence of the inhibition of prenylation of proteins that play an important role in the fusion of pOCs and in maintaining actin ring integrity in OCLs.
Collapse
Affiliation(s)
- J T Woo
- Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan
| | | | | | | |
Collapse
|
48
|
Abstract
Thyroid hormone (T3) and insulin-like growth factor I (IGF-I) are critical regulators of skeletal function. T3 increases IGF-I production in bone. To assess the potential role of IGF-I as a mediator of T3 actions, we characterized phenotypic markers of osteoblast activity in two osteoblast models, normal mouse osteoblasts and MC3T3-E1 cells, exposed to T3 alone or under conditions that interfere with IGF-I actions. T3 significantly increased osteoblast 3H-proline incorporation, alkaline phosphatase (ALP), and osteocalcin. Both alphaIR3, a neutralizing monoclonal antibody to the IGF-I receptor, and JB1, an IGF-I analogue antagonist, attenuated the stimulatory effects of T3. T3 effects also were decreased in cells transfected with antisense oligonucleotide (AS-ODN) to the IGF-I receptor gene. Both IGF-I and T3 had mitogenic effects that were inhibited by the antagonists. IGF-I by itself did not stimulate 3H-proline incorporation, ALP, and osteocalcin in the models used, revealing that although IGF-I is essential for the anabolic effects of T3, it acts in concert with other factors to elicit these phenotypic responses.
Collapse
Affiliation(s)
- B K Huang
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | | | | | | | | |
Collapse
|
49
|
Abstract
Parathyroid hormone (PTH) treatment of bone and kidney-derived cells not only activates adenylyl cyclase but also increases intracellular free calcium, and translocates protein kinase C (PKC) from cytosol to plasma membranes. We have found that acute phorbol ester pretreatment significantly decreases PTH-induced calcium transients and the effect of phorbol ester was antagonized by staurosporine (ST). Although the major effect of ST in that study was the reversal of the action of phorbol ester, it appeared that ST may also have promoted the effect of PTH directly. To further investigate the observation, we examined the effect of ST on the intracellular calcium transients induced by PTH and alpha-thrombin (alpha-TH). For calcium transient experiments, UMR-106 cells were loaded with 2 mM fluo-acetoxymethylester for 30 min at room temperature. The cells were then washed and suspended in buffer containing 1 mM calcium. Fluorescence was detected at 530 nm, with excitation at 505 nm. ST alone did not cause calcium transients, but enhanced the transients elicited by PTH when added 5 min before the hormone. Another protein kinase inhibitor H-7 likewise enhanced the calcium responses elicited by PTH, while genistein did not affect PTH response. Calcium transients elicited by alpha-TH were also enhanced by ST. The results suggest that there might be tonically activated endogenous protein kinase(s) which inhibit calcium signaling of some calcemic agents.
Collapse
Affiliation(s)
- S K Lee
- Research Institute of Immunobiology, Catholic Research Institutes of Medical Science, Catholic University of Korea, Seoul, Korea
| | | |
Collapse
|
50
|
Singh AT, Kunnel JG, Strieleman PJ, Stern PH. Parathyroid hormone (PTH)-(1-34), [Nle(8,18),Tyr34]PTH-(3-34) amide, PTH-(1-31) amide, and PTH-related peptide-(1-34) stimulate phosphatidylcholine hydrolysis in UMR-106 osteoblastic cells: comparison with effects of phorbol 12,13-dibutyrate. Endocrinology 1999; 140:131-7. [PMID: 9886817 DOI: 10.1210/endo.140.1.6456] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Studies were performed to determine the effects of PTH and related compounds on phosphatidylcholine (PC) hydrolysis in UMR-106 cells and the pathway by which the PTH effects occurred. The responses were compared with those of phorbol 12,13-dibutyrate (PDBu). Both bovine PTH-(1-34) [bPTH-(1-34)] and PDBu stimulated PC hydrolysis within 10 min. Significant effects were elicited by concentrations of 0.3-1 nM bPTH-(1-34) and 5 nM PDBu. Dose-dependent increases were seen at higher concentrations of both compounds, however, the response to bPTH-(1-34) was reduced at 30 nM. Bovine or human PTH-(1-34) and human PTH-related peptide-(1-34) [hPTHrP-(1-34)] were equipotent in their effects, whereas bovine [Nle(8,18)Tyr34]PTH-(3-34) amide [bPTH-(3-34)] and hPTH-(1-31) amide [hPTH-(1-31)] were less potent than bPTH-(1-34). bPTH-(3-34) did not antagonize the effects of bPTH-(1-34). Down-regulation of protein kinase C isozymes by 24-h treatment with PDBu completely prevented the stimulatory effect of PDBu on PC hydrolysis, but did not significantly affect the stimulatory effect of bPTH-(1-34). Both bPTH-(1-34) and PDBu stimulated transphosphatidylation of PC, indicating a phospholipase D-stimulated mechanism. The results suggest that in the UMR-106 cell line PTH can stimulate activation of PLD by a mechanism other than through protein kinase C.
Collapse
Affiliation(s)
- A T Singh
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611-3008, USA.
| | | | | | | |
Collapse
|