Deficiency of Lipocalin-2 Promotes Proliferation and Differentiation of Osteoclast Precursors via Regulation of c-Fms Expression and Nuclear Factor-kappa B Activation.
- Author:
Hyun Ju KIM
1
;
Boram OHK
;
Woo Youl KANG
;
Sook Jin SEONG
;
Kyoungho SUK
;
Mi Sun LIM
;
Shin Yoon KIM
;
Young Ran YOON
Author Information
- Publication Type:In Vitro ; Original Article
- Keywords: c-Fms; LCN2; NF-kappaB; Osteoclast
- MeSH: Acid Phosphatase; Animals; Apoptosis; Biological Processes; Bone Marrow; Bromodeoxyuridine; Cell Death; Cell Proliferation; Enzyme-Linked Immunosorbent Assay; Glycoproteins; Immunoblotting; Macrophage Colony-Stimulating Factor; Macrophages; Mice; Mice, Knockout; NF-kappa B; Osteoclasts*; Phosphorylation; RANK Ligand; T-Lymphocytes; Transcription Factors
- From:Journal of Bone Metabolism 2016;23(1):8-15
- CountryRepublic of Korea
- Language:English
- Abstract: BACKGROUND: Lipocalin-2 (LCN2), a small glycoprotein, has a pivotal role in diverse biological processes such as cellular proliferation and differentiation. We previously reported that LCN2 is implicated in osteoclast formation induced by receptor activator of nuclear factor-kappa B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). In the present study, we used a knockout mouse model to further investigate the role of LCN2 in osteoclast development. METHODS: Osteoclastogenesis was assessed using primary bone marrow-derived macrophages. RANKL and M-CSF signaling was determined by immunoblotting, cell proliferation by bromodeoxyuridine (BrdU) enzyme-linked immunosorbent assay (ELISA), and apoptosis by cell death detection ELISA. Bone morphometric parameters were determined using a micro-computed tomography system. RESULTS: Our results showed that LCN2 deficiency increases tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclast formation in vitro, a finding that reflects enhanced proliferation and differentiation of osteoclast lineage cells. LCN2 deficiency promotes M-CSF-induced proliferation of bone marrow macrophages (BMMs), osteoclast precursors, without altering their survival. The accelerated proliferation of LCN2-deficient precursors is associated with enhanced expression and activation of the M-CSF receptor, c-Fms. Furthermore, LCN2 deficiency stimulates the induction of c-Fos and nuclear factor of activated T cells c1 (NFATc1), key transcription factors for osteoclastogenesis, and promotes RANKL-induced inhibitor of kappa B (IkappaBalpha) phosphorylation. Interestingly, LCN2 deficiency does not affect basal osteoclast formation in vivo, suggesting that LCN2 might play a role in the enhanced osteoclast development that occurs under some pathological conditions. CONCLUSIONS: Our study establishes LCN2 as a negative modulator of osteoclast formation, results that are in accordance with our previous findings.
