Takada Yasunari, Aggarwal Bharat B
Cytokine Research Laboratory, Department of Experimental Therapeutics, Box 143, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
Blood. 2004 Dec 15;104(13):4113-21. doi: 10.1182/blood-2004-04-1607. Epub 2004 Aug 17.
In the current report, we investigated the possibility of a cross-talk between receptor activator of NF-kappaB ligand (RANKL) and tumor necrosis factor alpha (TNF-alpha) using macrophage cell lines derived from wild-type mice and from mice with genetic deletion of the type 1 TNF receptor (p60(-/-)), the type 2 TNF receptor (p80(-/-)), or both receptors (p60(-/-)p80(-/-)). Deletion of TNF receptors sensitized the cells to RANKL-induced NF-kappaB activation, in order from least to most sensitive of p60(-/-) less than p80(-/-) less than p60(-/-)p80(-/-). The effect on nuclear factor-kappaB (NF-kappaB) activation correlated with RANKL-induced IkappaBalpha kinase activation. Deletion of both TNF receptors also potentiated RANKL-induced c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1 and 2 (ERK1/2), and p38 mitogen-activated protein kinase (MAPK) activations in a dose- and time-dependent manner. Nitric oxide (NO) production and expression of inducible NO synthase (iNOS) and cyclooxygenase 2 (COX-2) induced by RANKL was also maximally induced in double knock-out cells. RANKL had no effect on the proliferation of wild-type cells, but deletion of TNF receptors induced growth modulatory effects. We also found that tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6), which mediates RANKL signaling, was constitutively bound to RANK in TNF receptor-deleted cells but not in wild-type cells, and this binding was enhanced by RANKL. Overall our results show that RANKL signaling is modulated by the TNF receptors and thus provide evidence of cross-talk between the receptors of 2 cytokines.
在本报告中，我们使用源自野生型小鼠以及1型肿瘤坏死因子受体（p60(-/-)）、2型肿瘤坏死因子受体（p80(-/-)）或两种受体均缺失（p60(-/-)p80(-/-)）的小鼠的巨噬细胞系，研究了核因子κB受体激活剂配体（RANKL）与肿瘤坏死因子α（TNF-α）之间相互作用的可能性。肿瘤坏死因子受体的缺失使细胞对RANKL诱导的核因子κB激活敏感，敏感性顺序为p60(-/-) ＜ p80(-/-) ＜ p60(-/-)p80(-/-)。对核因子κB（NF-κB）激活的影响与RANKL诱导的IκBα激酶激活相关。两种肿瘤坏死因子受体的缺失还以剂量和时间依赖性方式增强了RANKL诱导的c-Jun氨基末端激酶（JNK）、细胞外信号调节激酶1和2（ERK1/2）以及p38丝裂原活化蛋白激酶（MAPK）的激活。RANKL诱导的一氧化氮（NO）生成以及诱导型NO合酶（iNOS）和环氧化酶2（COX-2）的表达在双敲除细胞中也被最大程度地诱导。RANKL对野生型细胞的增殖没有影响，但肿瘤坏死因子受体的缺失诱导了生长调节作用。我们还发现，介导RANKL信号传导的肿瘤坏死因子（TNF）受体相关因子6（TRAF6）在肿瘤坏死因子受体缺失的细胞中与RANK组成性结合，而在野生型细胞中则不然，并且这种结合被RANKL增强。总体而言，我们的结果表明RANKL信号传导受肿瘤坏死因子受体调节，从而为两种细胞因子的受体之间存在相互作用提供了证据。
