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Open Access Highly Accessed Research article

Early response genes induced in chondrocytes stimulated with the inflammatory cytokine interleukin-1beta

Matthew P Vincenti1* and Constance E Brinckerhoff12

Author Affiliations

1 Department of Medicine, Dartmouth Medical School, Hanover, NH, USA

2 Department of Biochemistry, Dartmouth Medical School, Hanover, NH, USA

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Arthritis Res 2001, 3:381-388  doi:10.1186/ar331

The electronic version of this article is the complete one and can be found online at:


Received:31 May 2001
Revisions received:8 August 2001
Accepted:14 August 2001
Published:18 September 2001

© 2001 Vincenti and Brinckerhoff, licensee BioMed Central Ltd

Abstract

Recent work has established that IL-1β plays a central role in the inflammation and connective tissue destruction observed in both rheumatoid arthritis and osteoarthritis. These processes result from the ability of this inflammatory cytokine to activate expression of genes for neutral proteases, such as the matrix metalloproteinases. While IL-1β activates matrix metalloproteinase genes within several hours, it also activates immediate early genes, which are required for the later expression of matrix metalloproteinases and other arthritis-perpetuating genes, are also activated. To identify putative immediate early genes involved in IL-1β-mediated arthritic disease, a chondrocytic cell line (SW1353) was stimulated with this cytokine for 2 hours, total RNA was isolated, and expressed genes were identified by microarray analysis. This analysis identified alterations in the expression of multiple transcription factors, cytokines, growth factors and their receptors, adhesion molecules, proteases, and signaling intermediates that may contribute to inflammation and cartilage destruction in arthritis. Interestingly, confirmation of the expression of activating protein-1 family members by reverse transcriptase polymerase chain reaction revealed a preferential increase in junB, a known transcriptional antagonist of c-jun. The failure to observe induction of early growth response gene-1, which was detected by reverse transcriptase polymerase chain reaction to be substantially and transiently induced by 1 hour of IL-1 treatment, may be explained by the known instability of the message after early induction. However, this analysis has identified numerous IL-1β-responsive genes that warrant further investigation as mediators of disease in arthritis.

Keywords:
chondrocytes; interleukin-1; matrix metalloproteinases; signal transduction; transcription factors

Introduction

IL-1β is a proinflammataory cytokine that has myriad effects on cells, increasing proliferation, activating inflammatory responses, and inducing matrix remodeling through the production of neutral proteases. Since most cells can both express and respond to IL-1β, complex signaling programs are likely required to modulate the timing and magnitude of responses to this cytokine [1]. It is well documented that elevated expression of IL-1β in the joint results in the activation of inflammatory and degradative programs in synovial cells, contributing to the progression of rheumatoid arthritis [2]. Recent work by Hasty and coworkers [3] has demonstrated that local expression of IL-1β by articular chondrocytes activates autocrine gene expression, which contributes to the pathogenesis of osteoarthritis (OA). Furthermore, IL-1-receptor antagonists are effective inhibitors of inflammation and connective tissue destruction in animal models of arthritis [2,4,5]. Together, these studies implicate IL-1β as a central mediator of pathogenesis in arthritis.

Activation of this pathologic process is complex, most likely involving the activation or repression of numerous signal/transduction pathways, with subsequent effects on many genes. Our previous work has focused on the pathways by which IL-1β induces several members of the family of matrix metalloproteinases (MMPs), enzymes that are active at neutral pH and that collectively degrade the various components of the extracellular matrix. Specifically, we have focused on MMP-1 and MMP-13, interstitial collagenases that have the unique ability to initiate cleavage of the triple helix comprising the stromal collagens types I, II, and III. Elevated expression of MMP-1 and MMP-13 by stromal cells and chondrocytes in response to IL-1β contributes to the pathogenesis of connective tissue disorders [6,7,8,9,10,11]. Studies from this laboratory and others showed that IL-1 activates MMP-1 and MMP-13 gene expression through common signaling pathways [11,12,13,14,15]. Specifically, nuclear translocation of NF-κB and mitogen-activated protein kinase (MAPK) stimulation of activator protein-1 (AP-1) are required for transcription of cytokine-induced MMP-1 and MMP-13. Furthermore, cycloheximide blocks mRNA expression of both collagenases [11,16], indicating that expression of immediate early genes is required for MMP-1 and MMP-13 gene expression. Thus, IL-1β activation of collagenase gene expression requires the increased expression of a panel of essential transcription factors and signaling intermediates, as well as the initiation of signaling cascades that activate these factors.

IL-1 also contributes to the pathogenesis of arthritis by increasing the proliferation of mesenchymal cells and by enhancing the expression of other inflammatory mediators [17,18,19]. This complex alteration in cellular phenotype probably involves the coordinated increase and decrease of genes for cytokines and growth factors, adhesion molecules, and signaling intermediates. The recent availability of microarray technology has made it possible to perform an extensive analysis of IL-1 modulation of genes in cells that are central players in arthritic disease.

We therefore carried out a microarray analysis of IL-1β-stimulated chondrocytic cells in order to identify immediate early genes that could contribute to phenotypic changes relevant to OA. In these studies, we used the human chondrosarcoma cell line SW1353, for three important reasons. First, we, and others, have found that when treated with IL-1β, SW1353 cells serve as an appropriate model for primary chondrocytes in OA [11,20,21,22]. Second, the amount of total RNA required for microarray analysis precludes the use of primary human chondrocytes for these studies. Third, the inherent genetic variation in primary human chondrocyte cultures could bias the gene expression profile and lead to erroneous conclusions. We found increased expression of a large cohort of transcription factors, cytokines, growth factors, and signaling intermediate genes that are potential regulators of metalloproteinase gene expression, proliferation, and sustained inflammation. Alternatively, this was accompanied by a decrease in a modest number of genes also belonging to these categories, suggesting that IL-1β substantially reprograms gene expression in chondrocytes. A subset of these IL-1β-stimulated genes was then confirmed by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). This characterization of IL-1β-induced immediate early genes in chondrocytic cells identifies candidate mediators of the expression of colla-genase genes in arthritis.

Materials and methods

Cell culture

SW1353 chondrosarcoma cells were grown to confluence in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum (Hyclone, Logan, UT, USA), penicillin/streptomycin, and L-glutamine (Cellgro, Mediatech, Herndon, VA, USA). At the beginning of each experiment, cells were washed three times with Hank's buffered sterile saline (Cellgro) to remove traces of serum and were placed in Dulbecco's modified Eagle's medium containing 0.2% lactalbumin hydrolysate (Gibco/BRL, Rockville, MD, USA). Then cells were either left unstimu-lated or treated with 10 ng/ml recombinant IL-1β (Promega, Madison, WI, USA). This concentration of IL-1 was found to be optimal for activation of MMP-13 gene expression in these cells (data not shown).

Harvest and microarray analysis of mRNA

For microarray analysis, two confluent 150-mm plates of SW1353 cells were cultured in lactalbumin hydrolysate, or lactalbumin hydrolysate plus 10 ng/ml IL-1β, for 2 hours. Cells were then washed with Hank's buffered sterile saline solution and homogenized in 2 ml Triazol Reagent (Gibco/BRL), and RNA was purified in accordance with the manufacturer's instructions. The RNA pellets were stored in 70% ethanol and shipped on dry ice to Clontech Laboratories (Palo Alto, CA, USA) via express courier. Clontech analyzed the RNA using their Atlas Human Cancer 1.2 K array (1176 unique genes) and AtlasImage 1.0 software. We chose this data baseline because it represents a large number of genes that may be expressed during development and again during disease pathology. We further classified genes that increased or decreased by twofold or more, and sorted them using Microsoft Excel.

Reverse transcriptase polymerase chain reaction

A subset of genes whose expression was increased by IL-1β was then confirmed using a radioactive RT-PCR assay. Briefly, RNA was treated with DNAse I and then 2 μg was reverse transcribed with Moloney murine leukemia virus reverse transcriptase and oligodT primers. One tenth of the reverse transcriptase reaction was amplified using gene-specific primers, Platinum Taq DNA polymerase and 33PdATP. Single-band products were resolved on native acrylamide gels and visualized by autoradiography. Table 1 shows the gene-specific primers that were used.

Table 1. PCR primers and conditions

Results and discussion

Table 2 shows the results of an analysis using Clontech's Human Cancer 1.2 K Array and total RNA from SW1353 cells treated with IL-1β (10 ng/ml) for 2 hours. This analysis revealed substantial increases or decreases in the expression of several known IL-1β-responsive genes. These include transcription factors (panel A), cytokines, growth factors, and their receptors (panel B), proteases, matrix proteins, and adhesion molecules (panel C), as well as signaling intermediates and tumor suppressors (panel D).

Table 2. IL-1-responsive genes in chondrocytic cells

We focused on genes for transcription factors because they have been reported as IL-1-responsive immediate early genes in chondrocytes [23]. Members of the NF-κB, AP-1, and ets families of transcription factors substantially increased in the Human Cancer 1.2 K array (see Table 2, panel A). To confirm the effect of IL-1β on AP-1 family members, we assayed Jun family members by RT-PCR (Fig. 1). We found that the c-Jun and JunB genes increased transiently within 1 hour of IL-1 treatment, before the induction of the MMP-13 gene. The expression profiles for c-Jun and JunB were similar to the profile for egr-1, another immediate early gene in IL-1-stimulated chondrocytes [23]. In contrast, the JunD gene was constitutively expressed, and IL-1β increased this expression modestly. These data show that in IL-1β-stimulated chondrocytes, all three Jun family members are expressed and can contribute to MMP gene expression. Furthermore, RT-PCR analysis of the JunB gene (Fig. 1) validated the gene expression profile derived from the Human Cancer 1.2 K array (Table 2, panel A).

thumbnailFigure 1. Early gene expression in IL-1-treated SW1353 chondrocytes. SW1353 cells were stimulated for the indicated times with IL-1β (10 ng/ml) and total RNA was isolated. RNA was treated with DNAse I and then reverse transcribed with Moloney murine leukemia virus reverse transcriptase and oligodT primers. A tenth of the reverse transcriptase reaction was amplified using gene-specific primers, Platinum Taq DNA polymerase, and 33PdATP. Single-band products were resolved on native acrylamide gels and visualized by autoradiography.

Transcription factor genes that were modulated by IL-1β included members from the NF-κB family (relB, p100/p52, p105/p50, IκB-ε, c-rel, and p65), the AP-1 family (fra-1 and junB), and the ETS family (ets-1). While it is well established that NF-κB proteins translocate to the nucleus upon IL-1 stimulation [24], we were surprised to find so many family members expressed simultaneously. This suggests that in IL-1-stimulated chondrocytes, NF-κB family members may compete for dimerization partners and for binding sites in responsive genes.

Members of the AP-1 family of transcription factors are essential transcriptional activators for both the MMP-1 and MMP-13 genes [25,26,27], and these transcription factors are activated by extracellular stimuli through MAPK pathways [28]. JunB was identified as an IL-1-inducible gene in chondrocytes by the Human Cancer 1.2 K array (Table 1) and this finding was confirmed by RT-PCR (Fig. 1). Levels of JunB mRNA peaked within 1 hour of IL-1 stimulation and began to decline after 2 hours. This was somewhat surprising, since MAPK pathways do not activate JunB [29] and in some systems JunB antagonizes transcriptional activation by c-Jun [30]. Since c-Jun, JunB, and JunD are all expressed in IL-1-treated SW1353 chondrocytic cells, it is not clear which family member is responsible for transcriptional activation of collagenase genes. Perhaps the functional transcriptional complex is determined by induced expression and activation of AP-1 accessory proteins, such as the Fos family member Fra-1, or the ets family member ets-1 [31]. This cohort of AP-1, Fos, and ets family members may also preferentially bind to different AP-1 sites in MMP promoters, with subtle effects on gene expression [32].

egr-1 is an IL-1-inducible immediate early gene in chondrocytes [23] and has been implicated in the elevated MMP-1 gene expression observed in rheumatoid synoviocytes [33,34]. Surprisingly, egr-1 expression was increased only 1.3-fold in this Human Cancer 1.2 K array (data not shown). However, when this gene was analyzed by RT-PCR, we found a robust increase in egr-1 mRNA within 1 hour of IL-1 stimulation, which declined significantly by 2 hours (Fig. 1). Thus, the relatively short half-life of egr-1 mRNA resulted in an underestimation of IL-1 induction of this gene in the microarray. It is therefore probable that an array using RNA from cells treated for 1 hour with IL-1 would identify additional important genes.

IL-1β repressed three transcription factor genes, including HOX-4A, the retinoblastoma-like protein 2, and mothers against dpp homologue 4 (SMAD4). SMAD4 contributes to transforming growth factor-β (TGF-β)-dependent transcription of the alpha 2(I)-collagen (COL1A2) [35] and aggrecan [36] genes. Furthermore, our microarray data demonstrated that IL-1 inhibited Col2A1 expression by 1.6-fold in SW1353 cells (data not shown). It has been reported that IL-1 inhibition of Col2A1 gene expression requires the p38 MAPK pathway [37]. Perhaps inhibition of SMAD4 synthesis is another component of IL-1-dependent Col2A1 gene repression. While IL-1 promotes cartilage degradation through MMP synthesis and inhibits matrix deposition by reducing Col2A1 gene expression, TGF-β has the opposite effect on chondrocytes [3]. Thus, it is tempting to speculate that IL-1 antagonizes the effects of TGF-β by blocking expression of essential signaling intermediates, such as SMAD4.

Cytokines and growth factors and their receptors were a major group of IL-1-modulated genes in chondrocytes (Table 2, panel B). For instance, leukemia inhibitor factor precursor (LIF) was substantially induced by IL-1β in SW1353 cells, and this is consistent with previous reports of LIF as an IL-1-responsive gene in chondrocytes [38,39]. Recently, LIF was reported to induce MMP-13 gene expression [40], and this may contribute to the role of this cytokine in arthritis pathology [38]. IL-6 expression was increased in IL-1-treated cells, and while this may affect a variety of cellular functions in chondrocytes, this cytokine does not seem to be required for IL-1-induced suppression of proteoglycan synthesis in cartilage [41]. Interestingly, there was a concurrent increase in expression of platelet-derived growth factor (PDGF) subunits, and a decrease in PDGF receptor subunits. Perhaps this is a mechanism of ensuring paracrine, but not autocrine, effects of PDGF in cytokine-stimulated chondrocytes. The role of growth factors in IL-1-dependent effects is not clear cut, since IL-1 can both induce and inhibit proliferation of chondrocytes [17]. However, in the present model of SW1353 cells under serum-free conditions, we did not observe a mitogenic effect of IL-1 (data not shown).

Bone morphogenetic protein 4 (BMP4) is a member of the TGF-β superfamily of proteins and is required for chondrocyte differentiation and cartilage maintenance [42,43]. The observed suppression of its expression in chondrocytes by IL-1β (Table 2, panel B) is consistent with a previous report in osteoblastic cells [44] and suggests that IL-1β may enhance cartilage degradation by blocking an essential autocrine signal for chondrocyte maturation and function.

IL-1 induction of several MMP family members is seen, including collagenase-3 (MMP-13), matrilysin (MMP-7), and metalloelastase (MMP-12) (Table 2, panel C). The collagenase-1 (MMP-1) gene was not significantly induced in this array, and this is consistent with our previous findings that MMP-1 is expressed at lower levels than MMP-13 in SW1353 cells [11]. Furthermore, the magnitude of increase observed for these MMP genes was modest, despite the fact that MMP genes are strongly induced in response to IL-1β. However, the most likely explanation for the low level of induction seen here is the fact that MMPs are not 'early response genes'. Rather, they are the downstream targets of the signal/transduction pathways and transcription factors that do represent early responses. Indeed, RT-PCR confirmed that MMP-13 mRNA continues to increase 4 hours after IL-1 treatment (Fig. 1). This is consistent with our previously published finding that steady-state MMP-13 mRNA levels peak 12 hours after IL-1 treatment of chondrocytes [11].

Tenascin, an adhesion molecule that is expressed during cartilage development [45], was induced by IL-1β in SW1353 cells (Table 2, panel C). Interestingly, the tenascin gene has been reported to be IL-1-inducible in synovial cells and chondrocytes, and its expression is enhanced in rheumatoid arthritis and OA [46,47]. A possible physiologic consequence of IL-1β-induced tenascin expression is that it may promote chondrocyte migration towards the sites of lesions in OA [47]. IL-1β coordinately reduced expression of integrin a1, a cell-adhesion molecule that chondrocytes use to bind to type II collagen [48]. Thus, IL-1β treatment may modify adhesion molecule expression, so that matrix adhesion is compromised.

We found that IL-1β changed the expression levels for several signaling proteins and tumor suppressor genes (Table 2, panel D), but the significance of these changes is not clear. Proteins associated with G-protein signaling were both increased (rho6, Gem, and regulator of G protein signaling) and decreased (rho7, RAD1, and p160ROCK). Jagged, which is a transmembrane ligand for the Notch signaling pathway [49], is induced by IL-1β. Interestingly, jagged-1 is important for epithelial–mesenchymal cell interaction in development [50], and mutations in the jagged gene lead to Alagille syndrome, a congenital connective tissue disorder whose hallmarks include craniofacial and vertebral deformities [51]. Zhao and colleagues [52] identified frizzled (denoted FZD2) as the human homologue of the Drosophila polarity-determining gene. Of potential importance is the fact that frizzled family members have recently been implicated by Carson and colleagues in rheumatoid arthritis [53]. A new frizzled family member that is expressed in chondrocytes and is involved in skeletal morphogenesis has been described [54]. Perhaps down-regulation of frizzled family members by IL-1β is deleterious to chondrocyte function and can contribute to OA.

Conclusions

Along with confirming changes in gene expression already known to be associated with IL-1β stimulation, chondrocyte biology, and MMP gene regulation, this microarray identified several other induced and repressed genes whose roles in chondrocyte biology are yet to be defined. While the significance of these findings in terms of understanding IL-1 effects on chondrocytes is still uncertain, the documentation of these changes in gene expression may provide the basis for future studies on the molecular effects of IL-1 on chondrocytes and on other cell types as well.

Abbreviations

AP-1 = activator protein-1; COL2A1 = procollagen 2 alpha 1; egr-1 = early growth response gene-1; ets = erythroblastosis gene twenty-six; IL-1β = interleukin-1β; LH = lactalbumin hydrolysate; LIF = leukemia inhibitory factor; MAPK= mitogen-activated protein kinase; MMP = matrix metalloproteinase; NF-κB = nuclear factor-κB; OA = osteoarthritis; PDGF = platelet-derived growth factor; RT-PCR = reverse transcriptase polymerase chain reaction; SMAD4 = mothers against dpp homolog 4; TGF-β = transforming growth factor-β.

Acknowledgements

The authors would like to acknowledge the National Institute of Arthritis and Musculoskeletal and Skin Diseases (grants AR-46977 and AR-02024 to MPV; AR-26599 to CEB), the National Cancer Institute (grant CA-77267 to CEB) and the RGK Foundation, Austin Texas (grant to CEB) for funding of this research.

References

  1. Dinarello CA: Interleukin-1 and tumor necrosis factor: effector cytokines in autoimmune diseases.

    Semin Immunol 1992, 4:133-145. PubMed Abstract OpenURL

  2. Arend WP, Dayer JM: Inhibition of the production and effects of interleukin-1 and tumor necrosis factor alpha in rheumatoid arthritis.

    Arthritis Rheum 1995, 38:151-160. PubMed Abstract OpenURL

  3. Shlopov BV, Gumanovskaya ML, Hasty KA: Autocrine regulation of collagenase 3 (matrix metalloproteinase 13) during osteoarthritis.

    Arthritis Rheum 2000, 43:195-205. PubMed Abstract | Publisher Full Text OpenURL

  4. Gabay C, Arend WP: Treatment of rheumatoid arthritis with IL-1 inhibitors.

    Springer Semin Immunopathol 1998, 20:229-246. PubMed Abstract | Publisher Full Text OpenURL

  5. van den Berg WB, Joosten LA, van de Loo FA: TNF alpha and IL-1 beta are separate targets in chronic arthritis.

    Clin Exp Rheumatol 1999, 17:S105-214. PubMed Abstract OpenURL

  6. Vincenti MP, Coon CI, Lee O, Brinckerhoff CE: Regulation of collagenase gene expression by IL-1 beta requires transcriptional and post-transcriptional mechanisms.

    Nucleic Acids Res 1994, 22:4818-4827. PubMed Abstract OpenURL

  7. Vincenti MP, Coon CI, White LA, Barchowsky A, Brinckerhoff CE: src-related tyrosine kinases regulate transcriptional activation of the interstitial collagenase gene, MMP-1, in interleukin-1-stimulated synovial fibroblasts.

    Arthritis Rheum 1996, 39:574-582. PubMed Abstract OpenURL

  8. Vincenti MP, Schroen DJ, Coon CI, Brinckerhoff CE: v-src activation of the collagenase-1 (matrix metalloproteinase-1) promoter through PEA3 and STAT: requirement of extracellular signal-regulated kinases and inhibition by retinoic acid receptors.

    Mol Carcinog 1998, 21:194-204. PubMed Abstract | Publisher Full Text OpenURL

  9. Vincenti MP, Coon CI, Mengshol JA, Yocum S, Mitchell P, Brinckerhoff CE: Cloning of the gene for interstitial collagenase-3 (matrix metalloproteinase-13) from rabbit synovial fibroblasts: differential expression with collagenase-1 (matrix metalloproteinase-1).

    Biochem J 1998, 331:341-346. PubMed Abstract | Publisher Full Text OpenURL

  10. Vincenti MP, Coon CI, Brinckerhoff CE: Nuclear factor kappaB/p50 activates an element in the distal matrix metalloproteinase 1 promoter in interleukin-1beta-stimulated synovial fibroblasts.

    Arthritis Rheum 1998, 41:1987-1994. PubMed Abstract | Publisher Full Text OpenURL

  11. Mengshol JA, Vincenti MP, Coon CI, Barchowsky A, Brinckerhoff CE: Interleukin-1 induction of collagenase 3 (matrix metalloproteinase 13) gene expression in chondrocytes requires p38, c-Jun N-terminal kinase, and nuclear factor kappaB: differential regulation of collagenase 1 and collagenase 3.

    Arthritis Rheum 2000, 43:801-811. PubMed Abstract | Publisher Full Text OpenURL

  12. Barchowsky A, Frleta D, Vincenti MP: Integration of the NF-kappaB and mitogen-activated protein kinase/AP-1 pathways at the collagenase-1 promoter: divergence of IL-1 and TNF-dependent signal transduction in rabbit primary synovial fibroblasts.

    Cytokine 2000, 12:1469-1479. PubMed Abstract | Publisher Full Text OpenURL

  13. Bondeson J, Foxwell B, Brennan F, Feldmann M: Defining therapeutic targets by using adenovirus: Blocking NF-kappaB inhibits both inflammatory and destructive mechanisms in rheumatoid synovium but spares anti-inflammatory mediators.

    Proc Natl Acad Sci U S A 1999, 96:5668-5673. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  14. Han Z, Boyle DL, Aupperle KR, Bennett B, Manning AM, Firestein GS: Jun N-terminal kinase in rheumatoid arthritis.

    J Pharmacol Exp Ther 1999, 291:124-130. PubMed Abstract | Publisher Full Text OpenURL

  15. Reunanen N, Westermarck J, Hakkinen L, Holmstrom TH, Elo I, Eriksson JE, Kahari VM: Enhancement of fibroblast collagenase (matrix metalloproteinase-1) gene expression by ceramide is mediated by extracellular signal-regulated and stress-activated protein kinase pathways.

    J Biol Chem 1998, 273:5137-5145. PubMed Abstract | Publisher Full Text OpenURL

  16. McCachren SS, Greer PK, Niedel JE: Regulation of human synovial fibroblast collagenase messenger RNA by interleukin-1.

    Arthritis Rheum 1989, 32:1539-1545. PubMed Abstract OpenURL

  17. Blanco FJ, Geng Y, Lotz M: Differentiation-dependent effects of IL-1 and TGF-beta on human articular chondrocyte proliferation are related to inducible nitric oxide synthase expression.

    J Immunol 1995, 154:4018-4026. PubMed Abstract OpenURL

  18. Blanco FJ, Lotz M: IL-1-induced nitric oxide inhibits chondrocyte proliferation via PGE2.

    Exp Cell Res 1995, 218:319-325. PubMed Abstract | Publisher Full Text OpenURL

  19. Alvaro-Gracia JM, Zvaifler NJ, Firestein GS: Cytokines in chronic inflammatory arthritis. V. Mutual antagonism between inter-feron-gamma and tumor necrosis factor-alpha on HLA-DR expression, proliferation, collagenase production, and granulocyte macrophage colony-stimulating factor production by rheumatoid arthritis synoviocytes.

    J Clin Invest 1990, 86:1790-1798. PubMed Abstract OpenURL

  20. Heller RA, Schena M, Chai A, Shalon D, Bedilion T, Gilmore J, Woolley DE, Davis RW: Discovery and analysis of inflammatory disease-related genes using cDNA microarrays.

    Proc Natl Acad Sci U S A 1997, 94:2150-2155. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  21. Borden P, Solymar D, Sucharczuk A, Lindman B, Cannon P, Heller RA: Cytokine control of interstitial collagenase and collagenase-3 gene expression in human chondrocytes.

    J Biol Chem 1996, 271:23577-23581. PubMed Abstract | Publisher Full Text OpenURL

  22. Mix KS, Mengshol JA, Benbow U, Vincenti MP, Sporn MB, Brinck-erhoff CE: A synthetic triterpenoid selectively inhibits the induction of matrix metalloproteinases 1 and 13 by inflammatory cytokines.

    Arthritis Rheum 2001, 44:1096-1104. PubMed Abstract | Publisher Full Text OpenURL

  23. Goldring MB, Birkhead JR, Suen LF, Yamin R, Mizuno S, Glowacki J, Arbiser JL, Apperley JF: Interleukin-1 beta-modulated gene expression in immortalized human chondrocytes.

    J Clin Invest 1994, 94:2307-2316. PubMed Abstract OpenURL

  24. Karin M, Ben-Neriah Y: Phosphorylation meets ubiquitination: the control of NF-κB activity.

    Annu Rev Immunol 2000, 18:621-663. PubMed Abstract | Publisher Full Text OpenURL

  25. Porte D, Tuckermann J, Becker M, Baumann B, Teurich S, Higgins T, Owen MJ, Schorpp-Kistner M, Angel P: Both AP-1 and Cbfa1-like factors are required for the induction of interstitial collagenase by parathyroid hormone.

    Oncogene 1999, 18:667-678. PubMed Abstract | Publisher Full Text OpenURL

  26. Auble DT, Brinckerhoff CE: The AP-1 sequence is necessary but not sufficient for phorbol induction of collagenase in fibroblasts.

    Biochemistry 1991, 30:4629-4635. PubMed Abstract OpenURL

  27. Angel P, Imagawa M, Chiu R, Stein B, Imbra RJ, Rahmsdorf HJ, Jonat C, Herrlich P, Karin M: Phorbol ester-inducible genes contain a common cis elecent recognized by a TPA-modulated transacting factor.

    Cell 1987, 49:729-739. PubMed Abstract | Publisher Full Text OpenURL

  28. Garrington TP, Johnson GL: Organization and regulation of mitogen-activated protein kinase signaling pathways.

    Curr Opin Cell Biol 1999, 11:211-218. PubMed Abstract | Publisher Full Text OpenURL

  29. Karin M: The regulation of AP-1 activity by mitogen-activated protein kinases.

    J Biol Chem 1995, 270:16483-16486. PubMed Abstract | Publisher Full Text OpenURL

  30. Szabowski A, Maas-Szabowski N, Andrecht S, Kolbus A, Schorpp-Kistner M, Fusenig NE, Angel P: c-Jun and JunB antagonistically control cytokine-regulated mesenchymal-epidermal interaction in skin.

    Cell 2000, 103:745-755. PubMed Abstract | Publisher Full Text OpenURL

  31. Buttice G, Duterque-Coquillaud M, Basuyaux JP, Carrere S, Kurki-nen M, Stehelin D: Erg, an Ets-family member, differentially regulates human collagenase1 (MMP1) and stromelysin1 (MMP3) gene expression by physically interacting with the Fos/Jun complex.

    Oncogene 1996, 13:2297-2306. PubMed Abstract OpenURL

  32. White LA, Brinckerhoff CE: Two activator protein-1 elements in the matrix metalloproteinase-1 promoter have different effects on transcription and bind Jun D, c-Fos, and Fra-2.

    Matrix Biol 1995, 14:715-725. PubMed Abstract OpenURL

  33. Trabandt A, Aicher WK, Gay RE, Sukhatme VP, Fassbender HG, Gay S: Spontaneous expression of immediately-early response genes c-fos and egr-1 in collagenase-producing rheumatoid synovial fibroblasts.

    Rheumatol Int 1992, 12:53-59. PubMed Abstract OpenURL

  34. Trabandt A, Gay RE, Birkedal-Hansen H, Gay S: Expression of collagenase and potential transcriptional factors in the MRL/l mouse arthropathy.

    Semin Arthritis Rheum 1992, 21:246-251. PubMed Abstract OpenURL

  35. Zhang W, Ou J, Inagaki Y, Greenwel P, Ramirez F: Synergistic cooperation between Sp1 and Smad3/Smad4 mediates transforming growth factor beta1 stimulation of alpha 2(I)-collagen (COL1A2) transcription.

    J Biol Chem 2000, 275:39237-39245. PubMed Abstract | Publisher Full Text OpenURL

  36. Watanabe H, de Caestecker MP, Yamada Y: Transcriptional cross-talk between Smad, ERK1/2, and p38 mitogen-activated protein kinase pathways regulates transforming growth factor-beta-induced aggrecan gene expression in chondrogenic ATDC5 cells.

    J Biol Chem 2001, 276:14466-14473. PubMed Abstract | Publisher Full Text OpenURL

  37. Robbins JR, Thomas B, Tan L, Choy B, Arbiser JL, Berenbaum F, Goldring MB: Immortalized human adult articular chondrocytes maintain cartilage-specific phenotype and responses to interleukin-1beta.

    Arthritis Rheum 2000, 43:2189-2201. PubMed Abstract | Publisher Full Text OpenURL

  38. Lotz M, Moats T, Villiger PM: Leukemia inhibitory factor is expressed in cartilage and synovium and can contribute to the pathogenesis of arthritis.

    J Clin Inves 1992, 90:888-896. OpenURL

  39. Campbell IK, Waring P, Novak U, Hamilton JA: Production of leukemia inhibitory factor by human articular chondrocytes and cartilage in response to interleukin-1 and tumor necrosis factor alpha.

    Arthritis Rheum 1993, 36:790-794. PubMed Abstract OpenURL

  40. Varghese S, Yu K, Canalis E: Leukemia inhibitory factor and oncostatin M stimulate collagenase-3 expression in osteoblasts.

    Am J Physiol 1999, 276:E465-471. PubMed Abstract | Publisher Full Text OpenURL

  41. Van de Loo FA, Arntz OJ, Van den Berg WB: Effect of inter-leukin 1 and leukaemia inhibitory factor on chondrocyte metabolism in articular cartilage from normal and interleukin-6-deficient mice: role of nitric oxide and IL-6 in the suppression of proteoglycan synthesis.

    Cytokine 1997, 9:453-462. PubMed Abstract | Publisher Full Text OpenURL

  42. Luyten FP, Chen P, Paralkar V, Reddi AH: Recombinant bone morphogenetic protein-4, transforming growth factor-beta 1, and activin A enhance the cartilage phenotype of articular chondrocytes in vitro.

    Exp Cell Res 1994, 210:224-229. PubMed Abstract | Publisher Full Text OpenURL

  43. Shukunami C, Akiyama H, Nakamura T, Hiraki Y: Requirement of autocrine signaling by bone morphogenetic protein-4 for chondrogenic differentiation of ATDC5 cells.

    FEBS Lett 2000, 469:83-87. PubMed Abstract | Publisher Full Text OpenURL

  44. Virdi AS, Cook LJ, Oreffo RO, Triffitt JT: Modulation of bone morphogenetic protein-2 and bone morphogenetic protein-4 gene expression in osteoblastic cell lines.

    Cell Mol Biol (Noisy-le-grand) 1998, 44:1237-1246. PubMed Abstract OpenURL

  45. Pacifici M, Iwamoto M, Golden EB, Leatherman JL, Lee YS, Chuong CM: Tenascin is associated with articular cartilage development.

    Dev Dyn 1993, 198:123-134. PubMed Abstract OpenURL

  46. McCachren SS, Lightner VA: Expression of human tenascin in synovitis and its regulation by interleukin-1.

    Arthritis Rheum 1992, 35:1185-1196. PubMed Abstract OpenURL

  47. Chevalier X, Claudepierre P, Groult N, Godeau GJ: Influence of interleukin 1 beta on tenascin distribution in human normal and osteoarthritic cartilage: a quantitative immunohistochem-ical study.

    Ann Rheum Dis 1996, 55:772-775. PubMed Abstract OpenURL

  48. Loeser RF, Sadiev S, Tan L, Goldring MB: Integrin expression by primary and immortalized human chondrocytes: evidence of a differential role for alpha1beta1 and alpha2beta1 integrins in mediating chondrocyte adhesion to types II and VI collagen.

    Osteoarthritis Cartilage 2000, 8:96-105. PubMed Abstract | Publisher Full Text OpenURL

  49. Lindsell CE, Shawber CJ, Boulter J, Weinmaster G: Jagged: a mammalian ligand that activates Notch1.

    Cell 1995, 80:909-917. PubMed Abstract | Publisher Full Text OpenURL

  50. Mitsiadis TA, Henrique D, Thesleff I, Lendahl U: Mouse Serrate-1 (Jagged-1): expression in the developing tooth is regulated by epithelial-mesenchymal interactions and fibroblast growth factor-4.

    Development 1997, 124:1473-1483. PubMed Abstract | Publisher Full Text OpenURL

  51. Pilia G, Uda M, Macis D, Frau F, Crisponi L, Balli F, Barbera C, Colombo C, Frediani T, Gatti R, Iorio R, Marazzi MG, Marcellini M, Musumeci S, Nebbia G, Vajro P, Ruffa G, Zancan L, Cao A, DeVirgilis S: Jagged-1 mutation analysis in Italian Alagille syndrome patients.

    Hum Mutat 1999, 14:394-400. PubMed Abstract | Publisher Full Text OpenURL

  52. Zhao Z, Lee CC, Baldini A, Caskey CT: A human homologue of the Drosophila polarity gene frizzled has been identified and mapped to 17q21.1.

    Genomics 1995, 27:370-373. PubMed Abstract | Publisher Full Text OpenURL

  53. Sen M, Lauterbach K, El-Gabalawy H, Firestein GS, Corr M, Carson DA: Expression and function of wingless and frizzled homologs in rheumatoid arthritis.

    Proc Natl Acad Sci U S A 2000, 97:2791-2796. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  54. Hoang B, Moos M Jr, Vukicevic S, Luyten FP: Primary structure and tissue distribution of FRZB, a novel protein related to Drosophila frizzled, suggest a role in skeletal morphogenesis.

    J Biol Chem 1996, 271:26131-26137. PubMed Abstract | Publisher Full Text OpenURL