Xing Lianping, Bushnell Timothy P, Carlson Louise, Tai Zhenxing, Tondravi Mehrdad, Siebenlist Ulrich, Young Fay, Boyce Brendan F
Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, New York 14642, USA.
J Bone Miner Res. 2002 Jul;17(7):1200-10. doi: 10.1359/jbmr.2002.17.7.1200.
Expression of RANKL by stromal cells and of RANK and both NF-kappaB p50 and p52 by osteoclast precursors is essential for osteoclast formation. To examine further the role of RANKL, RANK, and NF-KB signaling in this process, we used NF-kappaB p50-/- ;p52-/- double knockout (dKO) and wild-type (WT) mice. Osteoclasts formed in cocultures of WT osteoblasts with splenocytes from WT mice but not from dKO mice, a finding unchanged by addition of RANKL and macrophage colony-stimulating factor (M-CSF). NF-kappaB dKO splenocytes formed more colony-forming unit granulocyte macrophage (CFU-GM) colonies than WT cells, but no osteoclasts were formed from dKO CFU-GM colonies. RANKL increased the number of CFU-GM colonies twofold in WT cultures but not in dKO cultures. Fluorescence-activated cell sorting (FACS) analysis of splenocytes from NF-kappaB dKO mice revealed a two-to threefold increase in the percentage of CD11b (Mac-1) and RANK double-positive cells compared with WT controls. Treatment of NF-kappaB dKO splenocytes with interleukin (IL)-1, TNF-alpha, M-CSF, GM-CSF, and IL-6 plus soluble IL-6 receptor did not rescue the osteoclast defect. No increase in apoptosis was observed in cells of the osteoclast lineage in NF-kappaB dKO or p50-/-;p52+/- (3/4KO) mice. Thus, NF-kappaB p50 and p52 expression is not required for formation of RANK-expressing osteoclast progenitors but is essential for RANK-expressing osteoclast precursors to differentiate into TRAP+ osteoclasts in response to RANKL and other osteoclastogenic cytokines.
基质细胞表达RANKL以及破骨细胞前体细胞表达RANK和NF-κB p50与p52对于破骨细胞形成至关重要。为了进一步研究RANKL、RANK和NF-κB信号在此过程中的作用，我们使用了NF-κB p50-/-;p52-/-双敲除（dKO）小鼠和野生型（WT）小鼠。WT成骨细胞与WT小鼠而非dKO小鼠的脾细胞共培养时可形成破骨细胞，添加RANKL和巨噬细胞集落刺激因子（M-CSF）后这一结果不变。NF-κB dKO脾细胞形成的集落形成单位粒细胞巨噬细胞（CFU-GM）集落比WT细胞更多，但dKO CFU-GM集落未形成破骨细胞。RANKL使WT培养物中的CFU-GM集落数量增加了两倍，但在dKO培养物中未增加。对NF-κB dKO小鼠脾细胞进行的荧光激活细胞分选（FACS）分析显示，与WT对照相比，CD11b（Mac-1）和RANK双阳性细胞的百分比增加了两到三倍。用白细胞介素（IL）-1、肿瘤坏死因子-α、M-CSF、粒细胞巨噬细胞集落刺激因子（GM-CSF）以及IL-6加可溶性IL-6受体处理NF-κB dKO脾细胞并不能挽救破骨细胞缺陷。在NF-κB dKO或p50-/-;p52+/-（3/4KO）小鼠的破骨细胞谱系细胞中未观察到凋亡增加。因此，NF-κB p50和p52的表达对于表达RANK的破骨细胞祖细胞的形成不是必需的，但对于表达RANK的破骨细胞前体细胞响应RANKL和其他破骨细胞生成细胞因子分化为TRAP+破骨细胞至关重要。
