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Updated: May 11, 2026

A RANKL-based Osteoclast Culture Assay of Mouse Bone Marrow to Investigate the Role of mTORC1 in Osteoclast Formation
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

AG490 inhibits NFATc1 expression and STAT3 activation during RANKL induced osteoclastogenesis

Chang-hong Li1, Jin-xia Zhao, Lin Sun

  • 1Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing 100191, PR China.

Biochemical and Biophysical Research Communications
|May 14, 2013
PubMed

Insights

The JAK2 inhibitor AG490 suppresses osteoclastogenesis by inhibiting STAT3 signaling and NFATc1 production. This finding suggests JAK2 inhibition could treat bone diseases involving excessive osteoclast activity.

Area of Science:

  • Immunology
  • Cell Biology
  • Bone Biology

Background:

  • The JAK/STAT pathway relays cytokine signals, impacting cell activation and proliferation.
  • Elevated JAK/STAT signaling is linked to allograft rejection and autoimmune diseases.
  • The specific role of JAK2/STAT3 in receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis remains unclear.

Purpose of the Study:

  • To investigate the effects of the JAK2 inhibitor AG490 on osteoclast differentiation.
  • To elucidate the role of the JAK2/STAT3 pathway in RANKL-induced osteoclastogenesis.

Main Methods:

  • Utilized the murine osteoclast precursor cell line RAW264.7.
  • Treated cells with AG490, a specific JAK2 inhibitor, and RANKL.
  • Assessed osteoclast differentiation, cell proliferation, cell cycle progression, and expression of key signaling molecules (NFATc1, c-Fos, Akt, ERK1/2, STAT3).
  • Employed small interfering RNA (siRNA) to down-regulate STAT3 expression.

Main Results:

  • AG490 significantly inhibited RANKL-induced osteoclastogenesis in RAW264.7 cells.
  • AG490 suppressed cell proliferation and delayed G1 to S phase transition.
  • AG490 reduced nuclear factor of activated T cells (NFAT) c1 expression but not c-Fos.
  • AG490 partially inhibited RANKL-induced phosphorylation of STAT3 at Ser(727) without affecting Akt or ERK1/2.
  • STAT3 down-regulation via siRNA suppressed tartrate-resistant acid phosphatase (TRAP), RANK, and NFATc1 expression.

Conclusions:

  • AG490 inhibits RANKL-induced osteoclastogenesis by suppressing NFATc1 production and cell proliferation through the STAT3 pathway.
  • These findings highlight the critical role of JAK2/STAT3 signaling in osteoclast differentiation.
  • Inhibition of JAK2 may represent a therapeutic strategy for bone diseases characterized by excessive osteoclastogenesis.

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