NADPH oxidase gp91phox contributes to RANKL-induced osteoclast differentiation by upregulating NFATc1

Abstract

Bone-marrow derived monocyte-macrophages (BMMs) differentiate into osteoclasts by M-CSF along subsequent RANKL stimulation possibly in collaboration with many other unknown cytokines released by pre- or mature osteoblasts. The differentiation process requires receptor activator of nuclear factor kappa-B ligand (RANKL)/RANK signaling and reactive oxygen species (ROS) such as superoxide anion (O2•−). Gp91phox, a plasma membrane subunit of NADPH oxidase (Nox), is constitutively expressed in BMMs and plays a major role in superoxide anion production. In this study, we found that mice deficient in gp91phox (gp91phox−/−) showed defects in osteoclast differentiation. Femurs of these mice produced osteoclasts at about 70% of the levels seen in femurs from wild-type mice, and accordingly exhibited excessive bone density. This abnormal bone growth in the femurs of gp91phox−/− mice resulted from impaired osteoclast differentiation. In addition, gp91phox−/− mice were defective for RANKL-induced expression of nuclear factor of activated T cells c1 (NFATc1). However, H2O2 treatment compensated for gp91phox deficiency in BMMs, almost completely rescuing osteoclast differentiation. Treating wild-type BMMs with antioxidants and superoxide inhibitors resulted in a differentiation defect resembling the phenotype of gp91phox−/− BMMs. Therefore, our results demonstrate that gp91phox-derived superoxide is important for promoting efficient osteoclast differentiation by inducing NFATc1 as a downstream signaling mediator of RANK.

Protective effect of GDNF‐engineered amniotic fluid‐derived stem cells on the renal ischaemia reperfusion injury in vitro

“…Recent studies revealed that a multicomponent phagocyte‐type NADPH oxidase is a major source of ROS production in many non‐phagocytic cells including renal mesangial cells . Gp91‐phox is a core regulatory subunit of NADPH oxidase . It is reported that when the balance between the anti‐oxidative and oxidative status was broken by oxygen, large numbers of ROS may activate mitochondrial stress pathways to cause mitochondrial injury .…”

“…29 Gp91-phox is a core regulatory subunit of NADPH oxidase. 30 It is reported that when the balance between the anti-oxidative and oxidative status was broken by oxygen, large numbers of ROS may activate mitochondrial stress pathways to cause mitochondrial injury. 31 protease activating factor 1, resulting in the production of apoptotic body.…”

The use of apocynin inhibits osteoclastogenesis

“…The NOX plasma membrane subunit Gp91 phox is important for osteoclast differentiation since it induces NFATc1, a downstream signaling mediator of RANK (Kang and Kim, 2016). NFATc1, the master switch for regulating osteoclast differentiation, binds directly to the promoter region of fusion-mediating molecules gene as Dcstamp .…”

“…Female p47 phoxÀ/À (part of NOX isoform 2) mice are protected from alcohol-induced bone resorption (Mercer et al, 2014). In a recent work, gp91 phoxÀ/À mice exhibited protected expression of transcription factors responsible for osteoclast formation, including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) and NF-kB (Kang and Kim, 2016). In a recent work, gp91 phoxÀ/À mice exhibited protected expression of transcription factors responsible for osteoclast formation, including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) and NF-kB (Kang and Kim, 2016).…”

“…Moreover, another study demonstrated that negative regulator of ROS (NRROS) attenuates osteoclast differentiation by nuclear factor-kB (NF-kB) activation as well as NOX1 and NOX2 degradation (Kim et al, 2015). In a recent work, gp91 phoxÀ/À mice exhibited protected expression of transcription factors responsible for osteoclast formation, including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) and NF-kB (Kang and Kim, 2016). Receptor activator of nuclear factor k-B (RANK) signaling upon RANK ligand (RANKL) binding induces cytoplasmic calcium oscillations, a phenomenon that provides an intracellular signal that leads to upregulation and autoamplification of NFATc1 .…”