| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Division of Immunology, Department of Molecular and Cellular Biology, School of Life Science (S.I.H., M.T., T.Y., M.N., M.Y., H.Y.); Division of Orthopedic Surgery, Department of Medicine of Sensory and Motor Organs (M.N.), Faculty of Medicine, Tottori University, and Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Science (H.Y.), Yonago, Tottori 683-8503, Japan; and The Jackson Laboratory (L.D.S.), Bar Harbor, Maine 04609
Address all correspondence and requests for reprints to: Dr. Shin-Ichi Hayashi, Division of Immunology, Department of Molecular and Cellular Biology, School of Life Science, Faculty of Medicine, Tottori University, 86 Nishi-Machi, Yonago, Tottori 683-8503, Japan. E-mail: shayashi{at}grape.med.tottori-u.ac.jp.
| Abstract |
|---|
|
|
|---|
B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) are critical for development of osteoclasts. The Toll-like receptor (TLR) family shares some of the downstream signaling with RANK. The TLR4 ligand, lipopolysaccharide (LPS), is reported to accelerate bone lysis; however, signaling via TLRs has never been reported to induce osteoclastogenesis without RANKL. In this study we showed that significant numbers of mature osteoclasts were generated from protein tyrosine phosphatase Src homology 2-domain phosphatase-1-defective Hcphme-v/Hcphme-v (mev/mev) bone marrow cells in the presence of M-CSF and LPS without addition of RANKL in culture. This M-CSF plus LPS-induced osteoclastogenesis was not inhibited by an anti-TNF
antagonistic antibody or by osteoprotegerin, a decoy receptor for RANKL. The replacement of RANKL by TLR ligands only occurred with LPS. Other ligands, a peptidoglycan for TLR2 or an unmethylated CpG oligonucleotide for TLR9, did not support osteoclast generation. The osteoclast precursors as well as RANKL-responsive osteoclast precursors were present in the Kit-positive cell-enriched fraction of bone marrow cells. Although mev/mev bone marrow cells required a comparable concentration of RANKL or TNF
as wild-type cells for the initiation of osteoclastogenesis, the numbers of multinucleated osteoclasts in mev/mev bone marrow cultures were significantly increased by the equivalent dose of RANKL or TNF
in the presence of M-CSF. These results indicate that a defect of Src homology 2-domain phosphatase-1 function not only accelerates physiological osteoclast development by RANKL/RANK, but also acquires a novel pathway for osteoclastogenesis by LPS. | Introduction |
|---|
|
|
|---|
B (NF-
B) ligand (RANKL) plays an essential role for the development of osteoclast precursors (OCPs) into tartrate- resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs) that resorb and remodel bones (1, 2, 3, 4). Functional M-CSF-deficient Csf1op/Csf1op (op/op) mice lack mature osteoclasts, resulting in severe osteopetrosis (5, 6). The op/op mice carrying the Bcl2 transgene are cured of the disease, and aged op/op mice show spontaneous reversal of osteopetrosis (7, 8). Therefore, signaling through the M-CSF receptor (Fms) is thought to function as a cell survival signal, and vascular endothelial growth factor partially replaces its function (9). Viable motheaten (mev/mev) mice mutated at the Src homology 2-domain phosphatase-1 (SHP-1) protein tyrosine phosphatase (Hcph) locus (10, 11) show accelerated osteoclastogenesis in vitro and in vivo (12, 13). Especially, numbers of TRAP+ MNCs were significantly increased (12, 13). In mice that are doubly homozygous for mutations at the Csf1 and Hcph loci (op/op mev/mev mice) (12), partial, but significant, bone marrow (BM) formation was observed, indicating that the signaling via the receptor tyrosine kinases is regulated negatively by SHP-1 (10, 11).
RANK and its ligand, RANKL, are members of TNF receptor and TNF superfamilies, respectively (14, 15). Targeted mutation in either gene prevents the development of osteoclasts, resulting in the development of osteopetrosis (16, 17). Therefore, RANK/RANKL signaling is thought to be essential for osteoclastogenesis. However, several recent studies using RANK-knockout (RANK-KO) mice showed that osteoclastogenesis was induced without RANK/RANKL signaling (18, 19). Although it is still not clear whether RANK/RANKL signaling is totally absent (20), mouse TNF
was reported to induce osteoclastogenesis in vivo and in vitro in the presence of M-CSF (18, 21).
Signaling via members of the Toll-like receptor (TLR) superfamily shares some of the downstream pathways, such as TNF receptor-associated factor 6 (TRAF6), NF-
B, and MAPK, with RANK (22, 23, 24). Recently, SHP-1 was reported to interact with TRAF6 (25). Although lipopolysaccharide (LPS) is known to accelerate the bone lysis (26, 27) and promote the survival of osteoclasts (28), signaling via TLRs has never been reported to induce mature osteoclasts without RANKL (4). We reported that in vivo LPS injection increased the generation of BM osteoclast precursors, but the maturation from even these treated cells into TRAP+cells required RANKL and M-CSF (29). Moreover, a cloned macrophage-like cell that lacks the p53 gene differentiates into mature osteoclasts without M-CSF; however, RANKL is essential for its maturation (29, 30, 31). Therefore, signaling via TLRs may be insufficient as a substitute for RANK signaling.
In this study we showed that SHP-1 deficiency enabled BM cells treated with LPS plus M-CSF in the absence of RANKL to give rise to mature osteoclasts that resorb bone. The osteoclastogenesis does not depend on the production of RANKL or TNF
. These results indicate that SHP-1 regulates downstream signaling for osteoclastogenesis through not only receptor tyrosine kinases, but also members of the TNF receptor superfamily.
| Materials and Methods |
|---|
|
|
|---|
Cell preparation and cultures
Mice were killed by cervical dislocation under ether anesthesia. BM cells were collected by flushing femoral shafts using a 26-gauge sterile needle. Cells from the peritoneal cavity (PECs) were obtained by injecting 48 ml ice-cold
MEM (Life Technologies, Inc., Grand Island, NY) supplemented with 10% fetal bovine serum (FBS; BioWhittaker, Walkersville, MD), 50 U/ml streptomycin, and 50 µg/ml penicillin (Meiji Chemical Co. Ltd., Tokyo, Japan).
To induce osteoclast differentiation, BM cells (12 x 104/well) and PECs (210 x 104/well) were cultured in 24-well plates (Corning Costar, Corning, NY) with 1 ml
MEM-supplemented 10% FBS and antibiotics in the presence of 50 ng/ml human M-CSF (a gift from Otsuka Pharmaceutical Co. Ltd., Tokushima, Japan) and/or 25 or 50 ng/ml recombinant human soluble RANKL (PeproTech EC Ltd., London, UK), 50 ng/ml recombinant mouse TNF
(R&D Systems, Inc., Place, NE), or TLR ligands for 6 d. According to the manufacturer, RANKL was produced by Escherichia coli, but the endotoxin level in the RANKL is less than 0.1 ng/µg. Cultures were fed every 3 d by replacing spent medium with fresh medium.
The number of multinucleated TRAP+cells (TRAP+ MNCs) was expressed as the mean ± SD of triplicate cultures (32). In some experiments, 20 ng/ml recombinant human IL-1
(a gift from Dr. S. Ono, Osaka University, Osaka, Japan) and 400 ng/ml human osteoprotegerin (OPG), a decoy receptor for RANKL (PeproTech EC Ltd.) were added to the cultures.
Pit formation assay
BM cells (5 x 103/well) were cultured on dentine slices (a gift from Dr. N. Udagawa, Matsumoto Dental University, Nagano, Japan) in 0.2 ml
MEM containing 10% FBS and 50 ng/ml M-CSF with 50 ng/ml soluble RANKL or 50 ng/ml LPS for 20 d in 96-well plates. After removal of the cells with 2 N NaOH, the slices were stained with 2% Coomassie Brilliant Blue R250 in methanol to visualize resorption pits (14).
TLR ligands
LPS from Salmonella minnesota Re 595 (Sigma-Aldrich Corp., St. Louis, MO) or E. coli 055 B5 (Difco, Detroit, MI) were used for in vitro and in vivo experiments. As both LPS preparations induce similar responses, most experiments used S. minnesota R595 LPS unless otherwise indicated. Peptidoglycan (PGN) from Staphylococcus aureus (Fluka Chemie, Buchs, Switzerland), used to stimulate TLR2, was dissolved in water, sonicated, and sterilized in a hot water bath. A phosphorothioated oligonucleotide (ODN; 5'-TCC ATG ACG TTC CTG ATG CT-3'; CpG), used as an unmethylated CpG ODN to stimulate TLR9, and a control phosphorothioated ODN (5'-GCT TGA TGA CTC AGC CGG AA-3') were purchased from Hokkaido System Science (Hokkaido, Japan) (33).
Antibodies (Abs)
An antagonistic rat antimouse TNF
monoclonal Ab (XT3) was purchased from Endogen (Woburn, MA) and used at 5 µg/ml for inhibition of TNF
activity. A nonantagonistic rat antimouse Kit Ab (ACK4) (34) was used as a control.
For flow cytometric analysis, monoclonal Abs against Fms (AFS98, biotinylated) (35), Kit [ACK2, phycoerythrin (PE)-conjugated [(34), or Mac-1 (CD11b, FITC-conjugated; M1/70, BD PharMingen, San Diego, CA) were used in Hanks medium containing 2% BSA (fraction V, Sigma-Aldrich Corp.) and 0.05% NaN3. The stained cells were analyzed using an EPICS-XL flow cytometer (Coulter Electronics, Hialeah, FL). Magnetic cell sorting for Kit-positive cell separation from BM cells was performed using the Mini-MACS column with PE-conjugated ACK2 and anti-PE antibody-conjugated microbeads (Miltenyi Biotec, Bergisch Gladbach, Germany).
RT-PCR
To determine the expression of TNF
(encoded by Tnf), RANKL (Tnfsf11), IL-1 receptor-associated kinase (IRAK) (Irak1), IRAK-M (Irak3), and hypoxanthine phosphoribosyl transferase (Hprt) genes, RT-PCR was performed. Total RNA was isolated using Isogen (Nippon Gene, Toyama, Japan) and was reverse transcribed using Reverse TraAce (Toyobo, Osaka, Japan). The DNA fragments were amplified from the mouse cDNAs by PCR. Hot-lid PCR amplification of cDNA equivalent to 20, 2, and 0.2 ng total RNA was carried out in 1x PCR buffer (1.5 mM MgCl2) containing 0.2 mM deoxy-NTPs (Takara, Shiga, Japan), 0.75 U rTaq DNA polymerase (Toyobo), and primers (used at 1.2 µM). Amplifications were carried out on DNA thermal cyclers (MJ Research, Inc., Watertown, MA). After an initial 3-min denaturing step (94 C), each PCR cycle consisted of 45-sec denaturing (94 C), 1-min annealing (55 or 60 C), and 1.5-min elongation (72 C). After the final cycle, the reaction was held for 3 min at 72 C. The PCR products were then separated on a 2% agarose gel, stained with ethidium bromide, and photographed. The primers used here were as follows: Tnf, 5'-CAC GCT CTT CTG TCT ACT GAA CTT CG-3' and 5'-GGC TGG GTA GAG AAT GGA TGA ACA CC-3'; Tnfsf11, 5'-CAG CAC TCA CTG CTT TTA TAG AAT CC-3' and 5'-AGC TGA AGA TAG TCT GTA GGT ACG C-3'; Irak1, 5'-GCC AGT GGA AAG TGA TGA GAG TG-3' and 5'-GAA AAA GCC TGA TGA CAG CAG TTG-3'; Irak3, 5'-TCC TTC AGG TGT CCT TCT CCA CTG-3' and 5'-CCT CTT CTC CAT TGG CTT GCT C-3'; and Hprt, 5'-AAT GAT CAG TCA ACG GGG GAC A-3' and 5'-CCA GCA AGC TTG CA ACCT TAA CCA-3'.
MAPK inhibitors
Inhibitors of the MAPK signaling pathway, PD098059 (2'-amino-3' methoxyflavone; Wako Pure Industry, Kyoto, Japan) for MAPK kinase (ERK1/2), SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole; Wako] for p38, and SP600125 [anthrax(1-9-cd)pyrazol-6(2H)-one; Tocris Cookson Ltd., Avonmouth, UK] for c-Jun N-terminal kinase, were dissolved to 20 mM in dimethylsulfoxide and used at 20 µM.
Statistical analysis
Data are presented as the mean ± SD. Statistical significance was assessed by t test.
| Results |
|---|
|
|
|---|
|
|
LPS-induced osteoclast development of mev/mev BM cells is not accounted for by the production of RANKL or TNF
A recent report showed that TNF
mimicked the function of RANKL for stimulating in vitro osteoclastogenesis of BM cells (21). BM cells from mev/mev and +/? mice were cultured with 50 ng/ml TNF
or 50 ng/ml RANKL in the presence of M-CSF for 6 d, and comparable numbers of osteoclasts in the cultures with TNF
or RANKL were observed in the BM cell cultures from each mouse stain (Fig. 3A
). We also incubated the cultures with M-CSF and IL-1
, but osteoclasts were not generated from either mev/mev or their littermate BM cells (Fig. 3A
).
|
production (28), we examined whether LPS-induced osteoclastogenesis was related to TNF
or RANKL production. If BM cells of mev/mev mice may produce high levels of TNF
or RANKL, osteoclastogenesis should occur in mev/mev BM cells. Therefore, BM cells from mev/mev and +/? mice were cultured with M-CSF, or M-CSF plus LPS for 3 d. Although LPS addition increased the expression of the TNF
(Tnf) gene transcript and induced a small amount of transcript of the RANKL (Tnfsf11) gene, doses of transcripts of Tnf and Tnfsf11 genes were comparable in both strains of mice (Fig. 3B
Recently, Kobayashi et al. (36, 37, 38, 39) reported that IRAK (encoded by Irak1) associated with MyD88 and IRAK-M (encoded by Irak3) regulate the signaling via TLRs. We assessed the expression of Irak1 and Irak3 in BM cells cultured with M-CSF or M-CSF plus LPS. Irak3 gene expression was increased in the presence of LPS as reported; however, no significant difference was detected between mev/mev and +/? cultured cells (Fig. 3B
). An alternative possibility was that mev/mev BM cells may require a smaller amount of TNF
or RANKL to induce osteoclast development than wild-type BM cells, and LPS induces sufficient production of TNF
or RANKL to support osteoclastogenesis only in mev/mev BM cells. Thus, minimal requirements of TNF
or RANKL to induce TRAP+ MNCs in cultures were assessed. More than 1 ng/ml TNF
or RANKL (Fig. 3C
) was needed to induce osteoclastogenesis from both mev/mev and wild-type littermate BM cells.
To further confirm these observations, mev/mev BM cells were cultured with anti-TNF
antagonistic antibody (XT3) or OPG in the presence of M-CSF and LPS, and the inhibitory effect on LPS-induced osteoclastogenesis in mev/mev BM cells was observed. OPG and XT3 completely inhibited M-CSF and RANKL (50 ng/ml)-induced and M-CSF and TNF
(50 ng/ml)-induced osteoclastogenesis, respectively; however, neither reagent inhibited M-CSF plus LPS-induced osteoclastogenesis (Fig. 4
). Although less than 1 ng/ml RANKL or TNF
might be produced by BM cells in the cultures, these results suggest that SHP-1 regulates the magnitude of osteoclastogenesis, but not the minimal requirements of RANKL or TNF
, and indicate that osteoclast development by mev/mev BM cells induced by M-CSF plus LPS may not be directly related to the production of RANKL or TNF
.
|
|
Moreover, to confirm whether LPS-responsive OCPs express Kit, we precultured BM cells with M-CSF for 3 d and dish-adherent cells were harvested. A majority (+/?; 87.4%, and mev/mev; 88.6%) of the precultured cells expressed Mac-1, and half (+/?; 52.2%, and mev/mev; 50.2%) of the cells were also Fms+; however, few (+/?; 0.32%, and mev/mev; 0.12%) of the precultured cells expressed Kit. The harvested cells were further cultured with M-CSF and RANKL, LPS, or RANKL plus LPS for 6 d. In the presence of M-CSF and RANKL, TRAP+ MNCs were generated from both mev/mev and +/? precultured BM cells, and mev/mev cells gave rise to significantly higher numbers of TRAP+ MNCs than +/? cells (Fig. 6B
). In contrast, few of precultured BM cells gave rise to TRAP+ MNCs in the presence of M-CSF and LPS, and addition of LPS inhibited osteoclastogenesis induced by M-CSF and RANKL (Fig. 6
, B and C) (29). These results indicate that BM cells precultured with M-CSF lose Kit-expression, and these cells from mev/mev mice lose the potential of LPS-responsive differentiation into osteoclasts.
|
, or IL-1
did not induce osteoclastogenesis in the presence of M-CSF (Fig. 7B
inhibited osteoclastogenesis induced by M-CSF and RANKL in control PECs as reported previously (29). IL-1
increased slightly the number of TRAP+ MNCs from wild-type PECs by M-CSF and RANKL. In contrast, osteoclast development from mev/mev PECs was absent or extremely low in all conditions tested (Fig. 7B
|
| Discussion |
|---|
|
|
|---|
in culture. It has been reported that the multinucleation and bone resorption of mev/mev osteoclasts induced by M-CSF and RANKL or by coculturing with stromal cells are accelerated (12, 13). Therefore, the total numbers of TRAP+-cells (mononuclear and multinuclear cells) were relatively comparable, but the numbers of TRAP+ MNCs in mev/mev cultures were significantly higher than those in +/? littermates (12, 13) (Hayashi, S.-I., unpublished observation). Wild-type BM cells gave rise to TRAP+ mononuclear cells in the presence of M-CSF and LPS; however, none or only a few multinucleated cells were observed in culture. Moreover, the numbers of TRAP+ mononuclear cells in +/? control mice were also significantly lower than those in SHP-1-deficient mev/mev BM cells. Previously, we reported that OCPs in the normal BM were enriched in Kit+ cells (40, 42). In the current study OCPs in +/? BM responding to M-CSF plus RANKL were enriched in the Kit+ cell-enriched population. Almost all TRAP+ mononuclear cells induced by M-CSF and LPS were derived from this fraction. OCPs responding to both RANKL and LPS in mev/mev BM were also enriched in the magnetic bead column-bound fraction. Kit+ cell-enriched populations from mev/mev BM cells expressed a higher level of Kit per cell than those from +/? cells. Few BM cells precultured with M-CSF for 3 d expressed Kit. In the presence of M-CSF and RANKL, osteoclasts were generated from both mev/mev and +/? precultured BM cells. In contrast, precultured BM cells gave rise to few TRAP+ MNCs in the presence of M-CSF and LPS. Moreover, LPS inhibited osteoclastogenesis induced by M-CSF and RANKL (29). Corresponding to losing Kit expression of BM cells precultured with M-CSF, these cells from mev/mev mice lose the potential of LPS-responsive differentiation into osteoclasts. These results indicated that the majority of LPS-responsive OCPs as well as RANKL-responsive OCPs in freshly prepared mev/mev BM cell populations might be present in the Kit+ cell fraction (29).
It is noted that a majority of c-Kit+ cells in freshly prepared BM cells are immature before expressing RANK (41). Lam et al. (20) proposed that TNF
could induce osteoclast differentiation only in precursors simultaneously or previously exposed to RANKL. Their conclusion was based on the results that BM cells cultured for 3 d with M-CSF and OPG lost the potential of TNF
-induced osteoclastogenesis, although they also mentioned that overnight preincubation with M-CSF and OPG did not affect their potential of responsiveness to TNF
(20). A majority of OCPs that respond to LPS and differentiate into osteoclasts are Kit+ cells, which might not express RANK. Even if previous exposure to RANKL is needed to maintain the responsiveness to LPS or TNF
in OCPs, OPG addition from 3 d before or from the initiation of culture must result in the same effect. We confirmed that overnight incubation with M-CSF and OPG did not affect the potential of LPS-induced osteoclastogenesis in mev/mev BM cells (data not shown). As Lam et al. (20) demonstrated, the presence of RANKL might be optimal for the maintenance of this potential; however, regardless of presence or absence of OPG, 3-d preculture with M-CSF reduced the potential to differentiate into osteoclasts induced by TNF
(29) or LPS. Moreover, several recent studies using RANK-KO mice showed that osteoclastogenesis is induced without RANK/RANKL signaling (18, 19). Therefore, LPS-induced osteoclastogenesis from mev/mev BM cells may be independent of RANK/RANKL signaling.
To assess whether mev/mev BM contains more Kit+ cells than +/? BM, flow cytometric analyses were performed repeatedly (data not shown). Some mev/mev BM contained a slightly higher ratio of Kit+ cells than +/? BM, but others were comparable to the wild-type BM. As mev/mev Kit+ cell-enriched populations still generated higher numbers of osteoclasts than Kit+ cell-enriched +/? populations, the presence of more Kit+ cells in mev/mev BM might not account for the accelerated osteoclastogenesis. Using a limiting dilution assay, we assessed the frequency of OCPs in BM (40). The mev/mev mice and +/? littermates contained, on the average, one OCP per 45.3 BM cells and one OCP per 34.8 BM cells, respectively. Single OCPs of mev/mev and +/? BM gave rise to 7.1 ± 9.6 and 11.8 ± 21.7 TRAP+ cells, respectively. The frequency of OCPs in BM cells and the growth of OCPs in culture are comparable to those in +/? littermates.
LPS, but not PGN or CpG, induced osteoclastogenesis of mev/mev BM cells in the presence of M-CSF. These three TLRs (TLR2, -4, and -9) share the downstream signaling, MyD88, TRAF6, NF-
B, and MAPK, but only TLR4, a receptor for LPS, is known to be another signaling pathway independent of independent of MyD88 (23, 43, 44). LPS might mimic the function of RANKL/RANK signaling, but not that of M-CSF/Fms signaling, in mev/mev BM osteoclastogenesis. In the absence of M-CSF, mev/mev BM osteoclastogenesis was not observed even if RANKL and LPS were added to the culture (data not shown). SHP-1 is reported to negatively regulate signaling via receptor protein tyrosine kinases, but the ligands, such as stem cell factor, vascular endothelial growth factor 164, platelet-derived growth factor, or insulin could not replace M-CSF function (45) (Yamada, T., unpublished observation). In addition to M-CSF, at least 1 ng/ml RANKL or TNF
is necessary to induce osteoclastogenesis in both mev/mev and their littermate (+/?) BM cells. M-CSF plus LPS-induced osteoclastogenesis was not inhibited by either OPG or anti-TNF
Ab. A recent report demonstrated that enriched BM macrophages cultured with M-CSF and thioglycolate-activated peritoneal macrophages produced less than 400 pg/ml TNF
((28). As we used whole BM cells in the steady state, less than 1/20th of the cell populations and approximately 1/50th of the LPS concentration were comparable to this report, and it is unlikely that our cultures contained more than 1 ng/ml TNF
. Therefore, production of RANKL or TNF
might not be involved in LPS-induced osteoclastogenesis of mev/mev BM cells.
Recently, it was shown that RANKL/RANK signaling activates SHP-1 recruitment to the complex containing TRAF6, and SHP-1 blocked the interaction of TRAF6 with the RANK signaling pathway (25). This suggests that SHP-1 might function in the TLR and TRAF6 signaling pathway. Mice lacking either triggering receptor expressed on myeloid cells 2 (TREM2) (46) or DAP12 are reported to develop osteopetrosis (47). These mice have fewer osteoclasts and lack the ability for bone resorption. DAP12, containing a cytoplasmic immunoreceptor tyrosine-based activation motif, is a TREM-related receptor, which recruits SHP-1. The mev/mev BM cells accelerate multinucleation (Fig. 1
) and bone resorption (12, 13). DAP12 dephosphorylation may be delayed in mev/mev BM cells, resulting in an increase in multinucleated osteoclasts.
After addition of PD098059, a MAPK kinase inhibitor, to the culture for 6 d, the total number of TRAP+ cells was relatively comparable to that in the absence of this reagent (data not shown). However, the number of TRAP+ MNCs was significantly reduced. MEK/ERK signaling may be involved in multinucleation of osteoclasts, suggesting that SHP-1 regulates the MEK/ERK signaling pathway. Moreover, as it is known that downstream signaling of TREM and DAP12 activate ERK, SHP-1 deficiency may accelerate ERK activation, resulting in an increase in multinucleated osteoclasts.
Recently, we demonstrated that peritoneal OCPs lose the potential to differentiate into mature osteoclasts if they were exposed to TLR ligands, TNF
, or even RANKL before an encounter with M-CSF and RANKL as a differentiation signal (29). Because SHP-1 deficiency accelerates this signaling pathway, OCPs in the mev/mev peritoneal cavity may lose the potential by the exposure of their ligands or unknown natural ligands. Finally, experiments using mev/mev mice lacking RANK or RANKL will provide conclusive evidence as to whether LPS may induce osteoclastogenesis in vivo. If so, LPS injection should cure the osteopetrosis in the double-mutant mice.
| Acknowledgments |
|---|
| Footnotes |
|---|
Current address for T.Y.: Laboratory for Lymphocyte Differentiation, Research Center for Allergy and Immunology, RIKEN Yokohama Institute, Yokohama 230-0045, Japan.
Abbreviations: Ab, Antibody; BM, bone marrow; FBS, fetal bovine serum; Hprt, hypoxanthine phosphoribosyl transferase; IRAK, IL-1 receptor-associated kinase; KO, knockout; LPS, lipopolysaccharide; M-CSF, macrophage-colony-stimulating factor; MNC, multinucleated cell; NF-
B, nuclear factor-
B; OCP, osteoclast precursor; ODN, oligonucleotide; OPG, osteoprotegerin; PE, phycoerythrin; PEC, peritoneal cavity cell; PGN, peptidoglycan; RANK, receptor activator of nuclear factor-
B; RANKL, receptor activator of nuclear factor-
B ligand; SHP, Src homology 2-domain phosphatase; TLR, Toll-like receptor; TRAF, TNF receptor-associated factor; TRAP, tartrate-resistant acid phosphatase; TREM, triggering receptor expressed on myeloid cell.
Received February 10, 2004.
Accepted for publication February 17, 2004.
| References |
|---|
|
|
|---|
induces osteoclastogenesis by directed stimulation of macrophages exposed to permissive levels of RANK ligand. J Clin Invest 106:14811488[Medline]
stimulates osteoclast differentiation by a mechanism independent of the ODF/RANKL-RANK interaction. J Exp Med 191:275286
B ligand stimulates recruitment of SHP-1 to the complex containing TNFR-associated factor 6 that regulates osteoclastogenesis. J Immunol 171:36203626
. Nature 408:600605[CrossRef][Medline]
. J Immunol 171:51305139
B (RANK) receptors. J Exp Med 190:17411754This article has been cited by other articles:
![]() |
J. Liu, S. Wang, P. Zhang, N. Said-Al-Naief, S. M. Michalek, and X. Feng Molecular Mechanism of the Bifunctional Role of Lipopolysaccharide in Osteoclastogenesis J. Biol. Chem., May 1, 2009; 284(18): 12512 - 12523. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Mori, S. Tsuji, M. Inui, Y. Sakamoto, S. Endo, Y. Ito, S. Fujimura, T. Koga, A. Nakamura, H. Takayanagi, et al. Inhibitory Immunoglobulin-Like Receptors LILRB and PIR-B Negatively Regulate Osteoclast Development J. Immunol., October 1, 2008; 181(7): 4742 - 4751. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |