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J Clin Invest. 2001 Jun;107(11):1375-85.

IL-4 abrogates osteoclastogenesis through STAT6-dependent inhibition of NF-kappaB.

Author information

1
Department of Orthopedic Research and Department of Pathology, Barnes-Jewish Hospital at Washington University School of Medicine, St. Louis, Missouri, USA. abuamery@msnotes.wustl.edu

Abstract

IL-4, an anti-inflammatory cytokine, inhibits osteoclast differentiation, but the basis of this effect has been unclear. Osteoclastogenesis requires activation of RANK, which exerts its biologic effect via activation of NF-kappaB. NF-kappaB activation is manifested by nuclear translocation and binding to DNA, events secondary to phosphorylation and dissociation of IkappaBalpha. It is shown here that IL-4 reduces NF-kappaB nuclear translocation by inhibiting IkappaB phosphorylation, thus markedly inhibiting NF-kappaB DNA binding activity and blocking osteoclastogenesis entirely. Residual translocation of NF-kappaB in the presence of IL-4, however, suggests that nuclear mechanisms must primarily account for inhibition of NF-kappaB DNA binding and blockade of osteoclastogenesis. To address this issue, this study examined whether IL-4-induced STAT6 transcription factor blocks NF-kappaB transactivation. The results show that excess unlabeled consensus sequence STAT6, but not its mutated form, inhibits NF-kappaB binding. Furthermore, exogenously added STAT6 protein inhibits NF-kappaB/DNA interaction. Further supporting a role for STAT6 in this process are the findings that IL-4 fails to block osteoclastogenesis in STAT6(-/-) mice but that this blockade can be restored with addition of exogenous STAT6. Thus, IL-4 obliterates osteoclast differentiation by antagonizing NF-kappaB activation in a STAT6-dependent manner.

PMID:
11390419
PMCID:
PMC209314
DOI:
10.1172/JCI10530
[Indexed for MEDLINE]
Free PMC Article

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