Osteoclast differentiation is impaired in the absence of inhibitor of κB kinase α
Osteoclast differentiation is impaired in the absence of inhibitor of κB kinase α
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DOI：
10.1074/jbc.m406392200
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发表时间：
2004-12-24
影响因子：
4.8
通讯作者：
Dougall, WC
中科院分区：
文献类型：
--
作者：
Chaisson, ML;Branstetter, DG;Dougall, WC
破骨细胞分化和乳腺发育都需要通过核因子κ B受体激活剂（RANK）进行信号传导，但RANK在这些组织中利用类似信号传导途径的程度仍不清楚。表达kappaB激酶α抑制剂（IKK α）的激酶失活形式的小鼠具有与RANK缺失小鼠相似的乳腺缺陷，但具有明显正常的破骨细胞功能。由于完全缺乏IKK α的小鼠有严重的皮肤和骨骼缺陷，这些缺陷与IKK α激酶活性无关，我们希望直接检查IKK α（-/-）小鼠的破骨细胞生成。我们发现，与完全缺乏破骨细胞的RANK基因敲除小鼠不同，IKK α（-/-）小鼠确实拥有正常数量的TRAP（+）破骨细胞。然而，这些细胞中只有32%是多核的，而野生型同窝仔中为57%。使用集落刺激因子1和RANK配体（RANKL）处理的IKK α（-/-）造血细胞在体外观察到破骨细胞生成的更严重缺陷，因为细胞未能形成大的多核破骨细胞。此外，IKK α（-/-）细胞中RANKL诱导的总体基因表达显著减弱，包括破骨细胞特异性基因，如TRAP、MMP-9和c-Src。IKK α不是RANKL介导的IkappaB α降解或有丝分裂原活化蛋白激酶磷酸化所必需的，但却是RANKL诱导的p100加工所必需的。用肿瘤坏死因子α（TNF α）联合RANKL处理IKK α（-/-）细胞导致部分破骨细胞生成的挽救，尽管缺乏p100加工。然而，TNF α单独或与转化生长因子β联合诱导破骨细胞分化的能力依赖于IKK α，这表明RANKL和TNF α之间的协同作用可以克服IKK α（-/-）细胞中的p100加工缺陷。
Signaling through the receptor activator of nuclear factor kappaB (RANK) is required for both osteoclast differentiation and mammary gland development, yet the extent to which RANK utilizes similar signaling pathways in these tissues remains unclear. Mice expressing a kinase-inactive form of the inhibitor of kappaB kinase alpha(IKKalpha) have mammary gland defects similar to those of RANK-null mice yet have apparently normal osteoclast function. Because mice that completely lack IKKalpha have severe skin and skeletal defects that are not associated with IKKalpha-kinase activity, we wished to directly examine osteoclastogenesis in IKKalpha(-/-) mice. We found that unlike RANK-null mice, which completely lack osteoclasts, IKKalpha(-/-) mice did possess normal numbers of TRAP(+) osteoclasts. However, only 32% of these cells were multinucleated compared with 57% in wild-type littermates. A more profound defect in osteoclastogenesis was observed in vitro using IKKalpha(-/-) hematopoietic cells treated with colony-stimulating factor 1 and RANK ligand ( RANKL), as the cells failed to form large, multinucleated osteoclasts. Additionally, overall RANKL-induced global gene expression was significantly blunted in IKKalpha(-/-) cells, including osteoclast-specific genes such as TRAP, MMP-9, and c-Src. IKKalpha was not required for RANKL-mediated IkappaBalpha degradation or phosphorylation of mitogen-activated protein kinases but was required for RANKL-induced p100 processing. Treatment of IKKalpha(-/-) cells with tumor necrosis factor alpha (TNFalpha) in combination with RANKL led to partial rescue of osteoclastogenesis despite a lack of p100 processing. However, the ability of TNFalpha alone or in combination with transforming growth factor beta to induce osteoclast differentiation was dependent on IKKalpha, suggesting that synergy between RANKL and TNFalpha can overcome p100 processing defects in IKKalpha(-/-) cells.