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Updated: Aug 22, 2025
09:37
A RANKL-based Osteoclast Culture Assay of Mouse Bone Marrow to Investigate the Role of mTORC1 in Osteoclast Formation
Published on: March 15, 2018
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ERK Inhibition Increases RANKL-Induced Osteoclast Differentiation in RAW 264.7 Cells by Stimulating AMPK Activation
Eun-Bi Choi1,2, Taiwo Samuel Agidigbi1, In-Soon Kang1,2
1Laboratory for Leukocyte Signaling Research, Department of Pharmacology and Toxicology, College of Medicine, Inha University, Incheon 22212, Korea.
International Journal of Molecular Sciences
|November 11, 2022
Summary
Extracellular signal-regulated kinases (ERKs) have a dual role in osteoclast differentiation. ERK inhibition promotes osteoclast formation in RAW 264.7 cells but inhibits it in bone marrow cells, impacting bone homeostasis.
Area of Science:
- Cell Biology
- Biochemistry
- Immunology
Background:
- Osteoclasts (OCs) are crucial for bone homeostasis, and their regulation is vital for skeletal health.
- Extracellular signal-regulated kinases (ERKs) are implicated in controlling OC development and function.
Purpose of the Study:
- To investigate the specific downstream signaling pathways influenced by ERK inhibition during osteoclast differentiation.
- To elucidate the differential roles of ERKs in osteoclastogenesis using distinct cell models.
Main Methods:
- Utilized ERK inhibitors (PD98059, U0126) and ERK2-specific small interfering RNA in RAW 264.7 cells.
- Assessed osteoclast differentiation in both RAW 264.7 cells and primary bone marrow-derived cells.
- Analyzed the phosphorylation status of key signaling molecules, including AMPK, p38 MAPK, Lyn, and mTOR.
- Quantified the expression levels of RANK, RANKL, and negative regulators of osteoclastogenesis.
Main Results:
- ERK inhibition paradoxically increased osteoclast differentiation in RAW 264.7 cells, suggesting a negative regulatory role in this cell line.
- Conversely, ERK inhibitors attenuated osteoclast differentiation in primary bone marrow-derived cells, indicating a positive regulatory role.
- ERK inhibition led to increased AMPK phosphorylation and RANK expression, while decreasing expression of negative mediators like IRF-8 and Bcl-6.
Conclusions:
- ERKs exhibit dichotomous functions in osteoclast differentiation, acting as negative regulators in RAW 264.7 cells and positive regulators in bone marrow-derived cells.
- These findings highlight the context-dependent role of ERK signaling in osteoclastogenesis and offer insights for therapeutic strategies targeting bone diseases.
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