| The Functional Analysis of MLKs-JNK Pathways in Osteoclast Formation |
| 파골세포 형성에 있어서 MLKs-JNK 경로의 역할 규명 |
| 지선영,정정,노아롱새미,문미란,*임미정 |
| 숙명여자대학교 |
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| Abstract |
Objective
s: Osteoclasts (OCs) are bone-resorbing multinucleated cells derived from hematopoietic progenitors of the
monocyte-macrophage lineage. OC precursors, such as bone marrow-derived macrophages (BMMs), are formed in
the presence of macrophage colony-stimulating factor (M-CSF) and differentiate into OCs in response to M-CSF and
receptor activator of nuclear factor κB ligand (RANKL). In this study, we investigated the role of mixed lineage
kinases (MLKs)-c-Jun amino-terminal kinase (JNK) pathways in OC formation.
Methods
We performed an OC formation assay and reverse transcription polymerase chain reaction (RT-PCR)
analysis.
Results
We first explored the role of JNK on osteoclst formation using mouse bone marrow (BM) culture system.
We found that OC formation was impaired when the JNK inhibitor was added either in early or late stage, suggesting
the requirement for JNK activation during OC formation. MLKs are serine/threonine kinases that regulate signaling
by the JNK. Since the JNK activity is specifically required for osteoclastogenesis, we examined the messenger
ribonucleic acid (mRNA) levels of MLKs in BMs, BMMs and OCs by RT-PCR. Among MLKs, the level of MLK3
mRNA expression is highest in BMs, BMMs and OCs. Moreover, we found that the mRNA expression of MLK2
and MLK3 is increased with the differentiation of BMs to BMMs, and is sustained in OCs. Finally we investigated
the role of MLK3 in OC differentiation using gene knock-down techniques. The silencing of MLK3 in BMMs partly
attenuated RANKL-induced OC differentiation.
Conclusions
These data suggest that JNK and MLK3 may positively regulate OC formation. |
| Key Words:
JNK, MLKs, Osteoclast |
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