Department of Medicine, Division of Clinical Pharmacology, NYU School of Medicine, 550 First Ave., New York, NY 10016, USA.
FASEB J. 2010 Jul;24(7):2325-33. doi: 10.1096/fj.09-147447. Epub 2010 Feb 24.
Adenosine regulates a wide variety of physiological processes via interaction with one or more G-protein-coupled receptors (A(1)R, A(2A)R, A(2B)R, and A(3)R). Because A(1)R occupancy promotes fusion of human monocytes to form giant cells in vitro, we determined whether A(1)R occupancy similarly promotes osteoclast function and formation. Bone marrow cells (BMCs) were harvested from C57Bl/6 female mice or A(1)R-knockout mice and their wild-type (WT) littermates and differentiated into osteoclasts in the presence of colony stimulating factor-1 and receptor activator of NF-kappaB ligand in the presence or absence of the A(1)R antagonist 1,3-dipropyl-8-cyclopentyl xanthine (DPCPX). Osteoclast morphology was analyzed in tartrate-resistant acid phosphatase or F-actin-stained samples, and bone resorption was evaluated by toluidine blue staining of dentin. BMCs from A(1)R-knockout mice form fewer osteoclasts than BMCs from WT mice, and the A(1)R antagonist DPCPX inhibits osteoclast formation (IC(50)=1 nM), with altered morphology and reduced ability to resorb bone. A(1)R blockade increased ubiquitination and degradation of TRAF6 in RAW264.7 cells induced to differentiate into osteoclasts. These studies suggest a critical role for adenosine in bone homeostasis via interaction with adenosine A(1)R and further suggest that A(1)R may be a novel pharmacologic target to prevent the bone loss associated with inflammatory diseases and menopause.
腺苷通过与一种或多种 G 蛋白偶联受体(A1R、A2AR、A2BR 和 A3R)相互作用,调节多种生理过程。由于 A1R 占据促进人单核细胞融合形成体外巨细胞,我们确定 A1R 占据是否同样促进破骨细胞功能和形成。骨髓细胞(BMCs)取自 C57Bl/6 雌性小鼠或 A1R 敲除小鼠及其野生型(WT)同窝仔鼠,并在集落刺激因子-1 和 NF-kappaB 配体受体激活剂存在的情况下,在存在或不存在 A1R 拮抗剂 1,3-二丙基-8-环戊基黄嘌呤(DPCPX)的情况下分化为破骨细胞。在抗酒石酸酸性磷酸酶或 F-肌动蛋白染色样本中分析破骨细胞形态,并通过甲苯胺蓝染色牙本质评估骨吸收。来自 A1R 敲除小鼠的 BMCs 形成的破骨细胞比来自 WT 小鼠的 BMCs 少,并且 A1R 拮抗剂 DPCPX 抑制破骨细胞形成(IC50=1 nM),具有改变的形态和降低的骨吸收能力。在诱导分化为破骨细胞的 RAW264.7 细胞中,A1R 阻断增加了 TRAF6 的泛素化和降解。这些研究表明,腺苷通过与腺苷 A1R 相互作用在骨稳态中起关键作用,并进一步表明 A1R 可能是预防与炎症性疾病和更年期相关的骨质流失的新型药物靶点。