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Farhangmehr F, Maurya MR, Tartakovsky DM, Subramaniam S. Information theoretic approach to complex biological network reconstruction: application to cytokine release in RAW 264.7 macrophages. BMC SYSTEMS BIOLOGY 2014; 8:77. [PMID: 24964861 PMCID: PMC4094931 DOI: 10.1186/1752-0509-8-77] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 06/04/2014] [Indexed: 12/27/2022]
Abstract
BACKGROUND High-throughput methods for biological measurements generate vast amounts of quantitative data, which necessitate the development of advanced approaches to data analysis to help understand the underlying mechanisms and networks. Reconstruction of biological networks from measured data of different components is a significant challenge in systems biology. RESULTS We use an information theoretic approach to reconstruct phosphoprotein-cytokine networks in RAW 264.7 macrophage cells. Cytokines are secreted upon activation of a wide range of regulatory signals transduced by the phosphoprotein network. Identifying these components can help identify regulatory modules responsible for the inflammatory phenotype. The information theoretic approach is based on estimation of mutual information of interactions by using kernel density estimators. Mutual information provides a measure of statistical dependencies between interacting components. Using the topology of the network derived, we develop a data-driven parsimonious input-output model of the phosphoprotein-cytokine network. CONCLUSIONS We demonstrate the applicability of our information theoretic approach to reconstruction of biological networks. For the phosphoprotein-cytokine network, this approach not only captures most of the known signaling components involved in cytokine release but also predicts new signaling components involved in the release of cytokines. The results of this study are important for gaining a clear understanding of macrophage activation during the inflammation process.
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Affiliation(s)
| | | | | | - Shankar Subramaniam
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, 92093-0412 La Jolla, CA, USA.
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Raychaudhuri N, Fernando R, Smith TJ. Thyrotropin regulates IL-6 expression in CD34+ fibrocytes: clear delineation of its cAMP-independent actions. PLoS One 2013; 8:e75100. [PMID: 24086448 PMCID: PMC3783445 DOI: 10.1371/journal.pone.0075100] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 08/11/2013] [Indexed: 11/18/2022] Open
Abstract
IL-6 plays diverse roles in normal and disease-associated immunity such as that associated with Graves’ disease (GD). In that syndrome, the orbit undergoes remodeling during a process known as thyroid-associated ophthalmopathy (TAO). Recently, CD34+ fibrocytes were found to infiltrate the orbit in TAO where they transition into CD34+ orbital fibroblasts. Surprisingly, fibrocytes display high levels of functional thyrotropin receptor (TSHR), the central antigen in GD. We report here that TSH and the pathogenic anti-TSHR antibodies that drive hyperthyroidism in GD induce IL-6 expression in fibrocytes and orbital fibroblasts. Unlike TSHR signaling in thyroid epithelium, that occurring in fibrocytes is completely independent of adenylate cyclase activation and cAMP generation. Instead TSH activates PDK1 and both AKT/PKB and PKC pathways. Expression and use of PKCβII switches to that of PKCµ as fibrocytes transition to TAO orbital fibroblasts. This shift is imposed by CD34− orbital fibroblasts but reverts when CD34+ fibroblasts are isolated. The up-regulation of IL-6 by TSH results from coordinately enhanced IL-6 gene promoter activity and increased IL-6 mRNA stability. TSH-dependent IL-6 expression requires activity at both CREB (−213 to −208 nt) and NF-κB (–78 to −62 nt) binding sites. These results provide novel insights into the molecular action of TSH and signaling downstream for TSHR in non-thyroid cells. Fibrocytes neither express adenylate cyclase nor generate cAMP and thus these findings are free from any influence of cAMP-related signaling. They identify potential therapeutic targets for TAO.
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Affiliation(s)
- Nupur Raychaudhuri
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Roshini Fernando
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Terry J. Smith
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Division of Metabolism, Endocrine, and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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Huang YF, Harrison JR, Kream BE. The Role of Proximal cAMP Responsive Element (CRE) in Parathyroid Hormone and cAMP Induction of Human Interleukin-6 Promoter Activity. J HARD TISSUE BIOL 2010. [DOI: 10.2485/jhtb.19.65] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Marques MR, dos Santos MCLG, da Silva AF, Nociti Jr FH, Barros SP. Parathyroid hormone administration may modulate periodontal tissue levels of interleukin-6, matrix metalloproteinase-2 and matrix metalloproteinase-9 in experimental periodontitis. J Periodontal Res 2009; 44:744-50. [DOI: 10.1111/j.1600-0765.2008.01186.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Broderick KE, Zhang T, Rangaswami H, Zeng Y, Zhao X, Boss GR, Pilz RB. Guanosine 3',5'-cyclic monophosphate (cGMP)/cGMP-dependent protein kinase induce interleukin-6 transcription in osteoblasts. Mol Endocrinol 2007; 21:1148-62. [PMID: 17341596 DOI: 10.1210/me.2005-0389] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Natriuretic peptides and nitric oxide (NO) activate the cGMP/cGMP-dependent protein kinase (PKG) signaling pathway and play an important role in bone development and adult bone homeostasis. The cytokine IL-6 regulates bone turnover and osteoclast and osteoblast differentiation. We found that C-type natriuretic peptide and the NO donor Deta-NONOate induced IL-6 mRNA expression in primary human osteoblasts, an effect mimicked by the membrane-permeable cGMP analog 8-chlorophenylthio-cGMP (8-CPT-cGMP). Similar results were obtained in rat UMR106 osteosarcoma cells, where C-type natriuretic peptide and 8-CPT-cGMP stimulated transcription of the human IL-6 promoter and increased IL-6 secretion into the medium. Cotransfection of type I PKG enhanced the cGMP effect on the IL-6 promoter, whereas small interfering RNA-mediated silencing of PKG I expression prevented the cGMP effect on IL-6 mRNA expression. Step-wise deletion of the IL-6 promoter demonstrated a cAMP response element to be critical for transcriptional effects of cGMP, and experiments with dominant interfering proteins showed that cGMP activation of the promoter required cAMP response element binding-related proteins, and, to a lesser extent, proteins of the CAAT enhancer-binding protein and activator protein-1 (Fos/Jun) families. 8-CPT-cGMP induced nuclear translocation of type I PKG and increased cAMP response element binding-related protein phosphorylation on Ser(133). PKG regulation of the IL-6 promoter appeared to be of physiological significance, because inhibitors of the NO/cGMP/PKG signaling pathway largely prevented fluid shear stress-induced increases of IL-6 mRNA in UMR106 cells.
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Affiliation(s)
- Kate E Broderick
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0652, USA
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Lu KC, Tseng CF, Wu CC, Yeung LK, Chen JS, Chao TY, Janckila AJ, Yam LT, Chu P. Effects of Calcitriol on Type 5b Tartrate-Resistant Acid Phosphatase and Interleukin-6 in Secondary Hyperparathyroidism. Blood Purif 2006; 24:423-30. [PMID: 16888370 DOI: 10.1159/000094899] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Accepted: 05/15/2006] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Secondary hyperparathyroidism (SHP) is characterized by high bone turnover and elevated serum bone remodeling markers. Elevation of serum interleukin-6 (IL-6) levels is also characteristic of end-stage renal disease. This study investigates the effects of intravenous calcitriol on serum bone resorptive markers, namely, type 5b tartrate-resistant acid phosphatase (TRACP5b) and IL-6 in patients with SHP. METHODS Intravenous calcitriol therapy was given for 16 weeks to 24 patients on maintenance hemodialysis with plasma intact parathyroid hormone (iPTH) levels >300 pg/ml. Blood was drawn at baseline and every 4 weeks for 16 weeks for determination of the levels of biochemical parameters, iPTH, IL-6 and bone remodeling markers, including bone-specific alkaline phosphatase (bAP) and TRACP5b. RESULTS Only 21 patients responded to the calcitriol therapy, with significant decrements in serum iPTH after 4 weeks of therapy and thereafter. After 16 weeks of calcitriol therapy, 21 patients had significant decrements in serum iPTH (707.9 +/- 317.8 vs. 205.0 +/- 63.1 pg/ml, p < 0.01). Prior to treatment, a significant correlation was found between increased levels of serum iPTH and IL-6 levels (r = 0.45, p < 0.05). After treatment, there was also a significant and parallel lowering of levels of serum iPTH, IL-6 (8.52 +/- 3.59 vs. 7.24 +/- 2.81 pg/ml, p < 0.01), bAP (54.68 +/- 36.17 vs. 24.55 +/- 13.84 U/l, p < 0.01) and TRACP5b (3.41 +/- 1.89 vs. 1.80 +/- 0.55 U/l, p < 0.01). Our results additionally showed significant positive correlationsbetween baseline levels of serum IL-6 and those of iPTH, bAP and TRACP5b. After 16 weeks of calcitriol treatment, the correlation between IL-6 and iPTH levels lost significance but levels of serum IL-6, bAP and TRACP5b remained significantly correlated. CONCLUSIONS Elevated levels of serum IL-6 and bone remodeling markers, namely, bAP and TRACP5b which are common features of SHP, are effectively suppressed by calcitriol therapy. This indicates that hyperparathyroidism not only accelerates bone remodeling but may also aggravate inflammation in patients on maintenance hemodialysis.
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Affiliation(s)
- Kuo-Cheng Lu
- Division of Nephrology, Department of Medicine, Cardinal Tien Hospital, School of Medicine, Fu-Jen Catholic University, Taipei, Taiwan
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Sahu SN, Khadeer MA, Robertson BW, Núñez SM, Bai G, Gupta A. Association of leupaxin with Src in osteoclasts. Am J Physiol Cell Physiol 2006; 292:C581-90. [PMID: 16914530 DOI: 10.1152/ajpcell.00636.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Leupaxin (LPXN), which belongs to the paxillin extended family of adaptor proteins, was previously identified as a component of the sealing zone in osteoclasts. LPXN was found to associate with several podosomal proteins, such as the protein tyrosine kinase Pyk2, the protein-tyrosine phosphatase-PEST (PTP-PEST), actin-binding proteins, and regulators of actin cytoskeletal reorganization. It was previously demonstrated that inhibition of LPXN expression resulted in reduced osteoclast-mediated resorption. In the current study, overexpression of LPXN in murine osteoclasts resulted in both enhanced resorptive activity and cell adhesion, as assessed by in vitro resorption assays. The overexpression of LPXN resulted in an increased association of Pyk2 with LPXN. In an attempt to determine an additional biochemical basis for the observed phenomenon in increased osteoclast activity, a coimmunoprecipitation screen for additional binding partners revealed that Src, a protein tyrosine kinase that is critical to both podosome formation and osteoclast function, was also associated with LPXN. After exposure to the pro-inflammatory and osteoclastogenic cytokine TNF-alpha, there was an increase in the level of Src that coimmunoprecipitated with LPXN. Our data indicate that association of the scaffold protein LPXN with Src adds further complexity to the organization of the podosomal signaling complex in osteoclasts.
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Affiliation(s)
- Surasri Nandan Sahu
- Department of Biomedical Sciences, 4G-29, Dental School, University of Maryland-Baltimore, 666 West Baltimore St., Baltimore, MD 21201, USA
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Patil C, Zhu X, Rossa C, Kim YJ, Kirkwood KL. p38 MAPK regulates IL-1beta induced IL-6 expression through mRNA stability in osteoblasts. Immunol Invest 2005; 33:213-33. [PMID: 15195698 PMCID: PMC1201547 DOI: 10.1081/imm-120034231] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Osteoblast-derived IL-6 functions in coupled bone turnover by supporting osteoclastogenesis favoring bone resorption instead of bone deposition. Gene regulation of IL-6 is complex occurring both at transcription and post-transcription levels. The focus of this paper is at the level of mRNA stability, which is important in IL-6 gene regulation. Using the MC3T3-E1 as an osteoblastic model, IL-6 secretion was dose dependently decreased by SB203580, a p38 MAPK inhibitor. Steady state IL-6 mRNA was decreased with SB203580 (2 microM) ca. 85% when stimulated by IL-1beta (1-5 ng/ml). These effects require de novo protein synthesis as they were inhibited by cycloheximide. p38 MAPK had minor effects on proximal IL-6 promoter activity in reporter gene assays. A more significant effect on IL-6 mRNA stability was observed in the presence of SB203580. Western blot analysis confirmed that SB203580 inhibited p38 MAP kinase, in response to IL-1beta in a dose dependent manner in MC3T3-E1 cells. Stably transfected MC3T3-E1 reporter cell lines (MC6) containing green fluorescent protein (GFP) with the 3'untranslated region of IL-6 were constructed. Results indicated that IL-1beta, TNFalpha, LPS but not parathyroid hormone (PTH) could increase GFP expression of these reporter cell lines. Endogenous IL-6 and reporter gene eGFP-IL-6 3'UTR mRNA was regulated by p38 in MC6 cells. In addition, transient transfection of IL-6 3'UTR reporter cells with immediate upstream MAP kinase kinase-3 and -6 increased GFP expression compared to mock transfected controls. These results indicate that p38 MAPK regulates IL-1beta-stimulated IL-6 at a post transcriptional mechanism and one of the primary targets of IL-6 gene regulation is the 3'UTR of IL-6.
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Affiliation(s)
| | | | - Carlos Rossa
- Department of Oral Biology
- Department of Surgery and Diagnosis, School of Dentistry at Araraquara, UNESP, Brazil
| | - Young Joon Kim
- Department of Oral Biology
- Department of Periodontics, Chonnam National University, Kwang-Ju, Korea
| | - Keith L. Kirkwood
- Department of Oral Biology
- Department of Periodontics and Endodontics
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, New York
- Corresponding Author: Keith L. Kirkwood, D.D.S., Ph.D. Assistant Professor, Departments of Periodontics & Endodontics and Oral Biology, Research Assistant Professor, Department of Pharmacology & Toxicology, University at Buffalo, 250 Squire Hall, 3435 Main Street, Buffalo, NY 14214-3008, Phone 716-829-2795, Fax 716-837-7623,
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Devidze N, Pfaff DW, Kow LM. Potentiation of genomic actions of estrogen by membrane actions in mcf-7 cells and the involvement of protein kinase C activation. Endocrine 2005; 27:253-8. [PMID: 16230781 DOI: 10.1385/endo:27:3:253] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Revised: 06/02/2005] [Accepted: 06/10/2005] [Indexed: 02/05/2023]
Abstract
It is now well established that estrogens (E) have at least two kinds of actions: genomic and nongenomic. But the relationship between these actions has hardly been explored. In this study we investigated this relationship in MCF-7 cells, a human breast cancer cell line, and explored the possible involvement of protein kinase C (PKC) signaling pathways. For this purpose a two-pulse paradigm was used: cells were treated with 17beta-estradiol (E), E conjugated with bovine serum albumin (E-BSA or fE'), or other test agents in the first pulse and with E in the second pulse following a 4-h interval. An E-BSA+E paradigm was used to show that replacement of E with the membrane-impermeable E-BSA in the first pulse could potentiate genomic actions of E, in the second pulse. To investigate involvement of signaling pathways, two PKC activators, phorbol 12,13-diacetate (PDAc) or phorbol 12-myristate 13-acetate (PMA), and inhibitors (chelerythrine chloride and H7-dihydrochloride) were used to replace E or E-BSA in the first pulse. PDAc was as effective as E or E-BSA in potentiating the genomic action of E in the second pulse, while PMA was almost without an effect. Conversely, the potentiating effects of E-BSA and PDAc were blocked by chelerythrine chloride but, interestingly, not by H7. The exact reason underlying these differences is not known. In summary, in MCF-7 cells a membrane action of E can potentiate a later genomic action and involves PKC signaling.
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Affiliation(s)
- Nino Devidze
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10021, USA.
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McCarty MF. Secondary hyperparathyroidism promotes the acute phase response – a rationale for supplemental Vitamin D in prevention of vascular events in the elderly. Med Hypotheses 2005; 64:1022-6. [PMID: 15780504 DOI: 10.1016/j.mehy.2004.03.041] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Accepted: 03/17/2004] [Indexed: 10/26/2022]
Abstract
Parathyroid hormone (PTH) promotes IL-6 secretion by osteoblasts, and may also up-regulate IL-6 production in the liver and adipose tissue; this may explain why serum IL-6 is markedly elevated in primary hyperparathyroidism, and low in hypoparathyroidism. IL-6 is the chief stimulus to hepatic production of many acute phase reactants, notably fibrinogen and C-reactive protein (CRP). Mild secondary hyperparathyroidism is common in elderly people, particularly at high latitudes during the winter, owing to poor vitamin D status. This may rationalize evidence that acute phase proteins show seasonal variations and are typically elevated in the elderly, whereas leisure physical activity is associated with a reduction in these proteins. In a recent clinical trial targeting elderly chronically ill patients, administration of vitamin D reduced serum levels of both CRP and IL-6; further such studies should assess the impact of physiologically meaningful doses of vitamin D on acute phase reactants in elderly subjects likely to have poor vitamin D status. Since elevations of CRP and fibrinogen may increase risk for thromboembolic vascular events, these considerations may help to explain the excess of coronary mortality observed during winter months, and suggest a role for supplemental vitamin D in preservation of vascular health. Moderate alcohol intake is associated with reduced serum PTH as well as decreased levels of CRP and fibrinogen; conceivably, modulation of PTH mediates, at least in part, the favorable impact of moderate drinking on the acute phase reactants.
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Affiliation(s)
- Mark F McCarty
- NutriGuard Research, 1051 Hermes Ave., Encinitas, CA 92024, USA.
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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] [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.
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Affiliation(s)
- Julie M Radeff
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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Kwan Tat S, Padrines M, Théoleyre S, Heymann D, Fortun Y. IL-6, RANKL, TNF-alpha/IL-1: interrelations in bone resorption pathophysiology. Cytokine Growth Factor Rev 2004; 15:49-60. [PMID: 14746813 DOI: 10.1016/j.cytogfr.2003.10.005] [Citation(s) in RCA: 672] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
All osteogenic cells (osteoclasts, osteoblasts) contribute individually to bone remodeling. Their cellular interactions control their cellular activities and the bone remodeling intensity. These interactions can be established either through a cell-cell contact, involving molecules of the integrin family, or by the release of many polypeptidic factors and/or their soluble receptor chains. These factors can act directly on osteogenic cells and their precursors to control differentiation, formation and functions (matrix formation, mineralization, resorption...). Here, we present the involvement of three groups of cytokines which seem to be of particular importance in bone physiology: interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) (TNF-alpha)/IL-1, and the more recently known triad osteoprotegerin (OPG)/receptor activator of NF-kappaB (RANK)/RANK ligand (RANKL). The interactions between these three groups are presented within the framework of bone resorption pathophysiology such as tumor associated osteolysis. The central role of the OPG/RANK/RANKL triad is pointed out.
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Affiliation(s)
- Steeve Kwan Tat
- Laboratoire de Physiopathologie de la Résorption Osseuse et Thérapie des Tumeurs Osseuses Primitives, Faculté de Médecine, 1 rue Gaston Veil, BP 53508, 44035 Nantes 1, France
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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] [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.
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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
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Guillén C, Martínez P, de Gortázar AR, Martínez ME, Esbrit P. Both N- and C-terminal domains of parathyroid hormone-related protein increase interleukin-6 by nuclear factor-kappa B activation in osteoblastic cells. J Biol Chem 2002; 277:28109-17. [PMID: 12000745 DOI: 10.1074/jbc.m111013200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Parathyroid hormone (PTH)-related protein (PTHrP) seems to affect bone resorption by interaction with bone cytokines, among them interleukin-6 (IL-6). Recent studies suggest that nuclear factor (NF)-kappaB activation has an important role in bone resorption. We assessed whether the N-terminal fragment of PTHrP, and its C-terminal region, unrelated to PTH, can activate NF-kappaB, and its relationship with IL-6 gene induction in different rat and human osteoblastic cell preparations. Here we present molecular data demonstrating that both PTHrP (1-36) and PTHrP (107-139) activate NF-kappaB, leading to an increase in IL-6 mRNA, in these cells. Using anti-p65 and anti-p50 antibodies, we detected the presence of both proteins in the activated NF-kappaB complex. This effect induced by either the N- or C-terminal PTHrP domain in osteoblastic cells appears to occur by different intracellular mechanisms, involving protein kinase A or intracellular Ca(2+)/protein kinase C activation, respectively. However, the effect of each peptide alone did not increase further when added together. Our findings lend support to the hypothesis that the C-terminal domain of PTHrP, in a manner similar to its N-terminal fragment, might stimulate bone resorption. These studies also provide further insights into the putative role of PTHrP as a modulator of bone remodeling.
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Affiliation(s)
- Carlos Guillén
- Bone and Mineral Metabolism Laboratory, Research Unit, Fundación Jiménez Díaz, 28040 Madrid, Spain
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Delannoy P, Lemonnier J, Haÿ E, Modrowski D, Marie PJ. Protein kinase C-dependent upregulation of N-cadherin expression by phorbol ester in human calvaria osteoblasts. Exp Cell Res 2001; 269:154-61. [PMID: 11525648 DOI: 10.1006/excr.2001.5301] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cell-cell adhesion mediated by cadherins is believed to play an essential role in the control of cell differentiation and tissue formation. Our recent studies indicate that N-cadherin is involved in human osteoblast differentiation. However, the signalling molecules that regulate cadherins in osteoblasts are not known. We tested the possibility that N-cadherin expression and function may be regulated by direct activation of protein kinase C (PKC) in human osteoblasts. Treatment of immortalized human neonatal calvaria (IHNC) cells with phorbol 12,13-dibutyrate (100 nM) transiently increased PKC activity. RT-PCR analysis showed that transient treatment with phorbol ester transiently increased N-cadherin mRNA levels at 4-12 h. Western blot analysis showed that N-cadherin protein levels were increased by phorbol ester at 24-48 h, and this was confirmed by immunocytochemical analysis. In contrast, E-cadherin expression was not affected. Transient treatment of IHNC cells with phorbol ester increased cell-cell aggregation, which was suppressed by neutralizing N-cadherin antibody, showing that the increased N-cadherin induced by phorbol ester was functional. Finally, phorbol ester dose-dependently increased alkaline phosphatase activity, an early marker of osteoblast differentiation. This effect was comparable to the promoting effect of BMP-2, a potent activator of osteoblast differentiation. These data show that direct activation of PKC by phorbol ester increases N-cadherin expression and function, and promotes ALP activity in human calvaria osteoblasts, which provides a signaling mechanism by which N-cadherin is regulated and suggests a role for PKC in N-cadherin-mediated control of human osteoblast differentiation.
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Affiliation(s)
- P Delannoy
- INSERM U 349 affiliated CNRS, Lariboisière Hospital, Paris, France
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Dossing DA, Radeff JM, Sanders J, Lee SK, Hsieh MR, Stern PH. Parathyroid hormone stimulates translocation of protein kinase C isozymes in UMR-106 osteoblastic osteosarcoma cells. Bone 2001; 29:223-30. [PMID: 11557365 DOI: 10.1016/s8756-3282(01)00507-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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.
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Affiliation(s)
- D A Dossing
- Department of Molecular Pharmacology, Northwestern University Medical School, Chicago, IL 60611, USA
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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] [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.
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Affiliation(s)
- J M Radeff
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611, USA
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18
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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] [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.
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Affiliation(s)
- Z Nagy
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611, USA
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Tetradis S, Bezouglaia O, Tsingotjidou A. Parathyroid hormone induces expression of the nuclear orphan receptor Nurr1 in bone cells. Endocrinology 2001; 142:663-70. [PMID: 11159837 DOI: 10.1210/endo.142.2.7926] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Following PTH treatment, immediate changes in osteoblast gene expression involve induction of primary response genes. Primary gene products subsequently mediate the osteoblast response to PTH. Using representational difference analysis (RDA) to isolate primary genes induced by PTH in osteoblasts, we identified Nurr1, a member of the NGFI-B nuclear orphan receptor subfamily. Nurr1 binds DNA as a monomer but also heterodimerizes with the 9-cis retinoic acid receptor (RXR). Nurr1's importance in retinoic acid, vitamin D, and thyroid hormone signaling has been hypothesized. Nurr1 messenger RNA (mRNA) levels were maximal at 1 h and at 10 nM of PTH in primary mouse osteoblasts (MOB). Activation of the PKA and PKC pathways by 10 microM forskolin and 1 microM PMA, respectively, induced Nurr1 mRNA levels. However, inhibition of the PKA but not the PKC pathway significantly inhibited the PTH induction of Nurr1. Moreover, PTH(3-34) at 1-100 nM did not induce Nurr1 mRNA levels. Thus, PTH induction of Nurr1 in primary mouse osteoblasts is mediated primarily through the cAMP/PKA pathway. PTH also stimulated Nurr1 protein in MOB cells and Nurr1 mRNA in calvarial organ cultures. Nurr1 induction represents a potential cross-talk mechanism between PTH and steroid hormone signaling at the transcription factor level.
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Affiliation(s)
- S Tetradis
- Division of Diagnostic and Surgical Sciences, UCLA School of Dentistry, Los Angeles, California 90095-1668, USA.
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