Stimulation of osteoclastogenesis by enhanced levels of MIP-1alpha in BALB/c mice in vitro.
OBJECTIVE
We compared osteoclast (OC) formation in bone marrow-derived macrophages (BMM) from C57BL/6 (B/6) and BALB/c (B/c) mice. After stimulation of receptor activator of nuclear factor-kappaB ligand (RANKL), enhanced OC formation and higher level of macrophage inflammatory protein-1alpha (MIP-1alpha) were observed in the BMM from B/c mice. In this study, we determined whether MIP-1alpha is responsible for stimulated OC formation in the BMM.


METHODS
OC formation was evaluated in BMM. Expression of MIP-1alpha during OC formation was analyzed at the mRNA and protein levels. Apoptosis of mature OCs was evaluated by observing the degradation of DNA. Activation of nuclear factor-kappaB (NF-kappaB) was measured by electrophoretic mobility shift assay.


RESULTS
After stimulation by RANKL expression of MIP-1alpha at the mRNA and protein levels was much higher in BMM from B/c mice than in BMM from B/6 mice. Transcripts of the MIP-1alpha receptors, CCR1 and CCR5, were present at similar levels in unstimulated BMM of the two strains. Blockade of MIP-1alpha inhibited OC formation, and exogenously added MIP-1alpha stimulated it in RANKL-stimulated BMM. MIP-1alpha affected not only the early precursors but also mature OCs. It prevented apoptosis of mature OCs by activating NF-kappaB, and the effect of RANKL on survival was dependent on its ability to induce MIP-1alpha.


CONCLUSIONS
MIP-1alpha, induced by RANKL during OC differentiation, increases OC formation by acting on OC progenitor cells, and prolongs survival of mature OC via signaling through NF-kappaB. The enhanced OC formation in BMM from B/c mice could be due to, at least in part, to their higher levels of MIP-1alpha.
Lee
Ji-Eun
JE
Department of Biological Sciences and Immunomodulation Research Center, University of Ulsan, Ulsan, Korea.
Shin
Hyun-Hee
HH
Lee
Eun-A
EA
Van Phan
Tien
T
Choi
Hye-Seon
HS
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002454:Cell Differentiation; D054407:Chemokine CCL4; D019742:Chemokines, CC / Q000502:physiology*; D008264:Macrophages / Q000166:cytology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000502:physiology*; D053245:RANK Ligand / Q000494:pharmacology; D013045:Species Specificity
C496535:Ccl4 protein, mouse; D054407:Chemokine CCL4; D019742:Chemokines, CC; D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse