RelA/p65 promotes osteoclast differentiation by blocking a RANKL-induced apoptotic JNK pathway in mice
J. Clin. Invest. Sergio Vaira, et al. 118:2088 doi:10.1172/JCI33392 [
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Figure 4The absence of
RelA leads to enhanced JNK activation.
(
A) Pre-OCs (BMMs cultured for 2 days with M-CSF and RANKL) generated from
Rela+/+ (black bars) and
Rela–/– (gray bars) mice were then starved of serum and cytokines and restimulated with RANKL for the indicated times prior to RNA extraction and real-time quantitative PCR for
xiap,
Gadd45b, and
Mkp5.
Rela–/– pre-OCs show significantly less induction of
xiap,
Gadd45b and
Mkp5. *
P < 0.5, **
P < 0.01 compared to
Rela+/+ at the same time point. (
B)
Rela+/+ and
Rela–/– pre-OCs were starved and restimulated with RANKL for the indicated times, and total lysates were analyzed by immunoblot for pJNK, demonstrating enhanced JNK activation in
Rela–/– cultures. A parallel blot with equal loading was used to assess total JNK protein. (
C)
Rela+/+ and
Rela–/– BMMs were cultured in RANKL, with or without the JNK inhibitor SP600125 (1 μm), for 36 hours Apoptosis was then assessed by DNA fragmentation assay. RANKL-mediated apoptosis was abrogated by the JNK inhibitor in
Rela–/– cells. The data are representative of 3 independent experiments.
†P < 0.05
Rela–/– versus
Rela+/+ or Rela–/– with SP600125. (
D)
Rela+/+ and
Rela–/– BMMs were cultured in osteoclastogenic conditions for 8 days, with or without SP600125 for the first 36 hours, showing rescue of differentiation with short-term JNK inhibition. Scale bar: 200 μm.
