RGS18 acts as a negative regulator of osteoclastogenesis by modulating the acid-sensing OGR1/NFAT signaling pathway
RGS18 acts as a negative regulator of osteoclastogenesis by modulating the acid-sensing OGR1/NFAT signaling pathway
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DOI：
10.1359/jbmr.070612
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发表时间：
2007-10-01
影响因子：
6.2
通讯作者：
Ishii, Masaru
中科院分区：
文献类型：
--
作者：
Iwai, Kaori;Koike, Masato;Ishii, Masaru
简介：破骨细胞是由RANK/RANKL系统刺激的单核巨噬细胞/单核细胞谱系前体分化而来的骨吸收多核巨细胞。G蛋白信号调节因子（Regulators of G-protein signaling，RGS）家族是一组促进异源三聚体G蛋白α亚基上的内源性GTP水解的蛋白质，在多种组织和器官的G蛋白介导的细胞信号生理调节中发挥重要作用。我们研究的表达和功能的RGS 18，髓系特异性的RGS蛋白，在破骨细胞genetics.Materials和方法：巨噬细胞/单核细胞系细胞系，RAW264.7，和主要的破骨细胞前体单核细胞来源于小鼠骨髓培养的巨噬细胞集落刺激因子（M-CSF）（骨髓来源的单核细胞[BMPs]）在这项研究中使用。两种细胞类型在RANKL激活后均分化为破骨细胞样细胞。通过基因特异性RT-PCR评估不同RGS蛋白（包括RGS 18）的表达。使用特异性多克隆抗体通过免疫组织化学检查IZGS 18在骨组织中天然破骨细胞以及RAW 264.7细胞中的亚细胞分布。使用针对RGS 18的短干扰RNA来抑制这些细胞类型中内源性RGS 18的功能。NFATc 1，破骨细胞生成转录因子，对外部酸中毒的激活进行了评估，通过可视化的核定位NFATc 1可视化与抗NFATc 1 antibody.Results：RAW264.7和BMM细胞都表达mRNA的10种不同的哺乳动物RGS蛋白，包括RGS 18。两种细胞类型的RANKL均显著抑制RGS 18的表达，并且使用RNA干扰抑制RGS 18功能显著增强了RANKL刺激下的破骨细胞生成。RGS 18抑制的效果通过阻断质子敏感OGR 1信号传导而逆转，并且外源性RGS 18的过表达抑制细胞外酸中毒介导的NFATc 1活化。小鼠骨组织的免疫组化研究显示RGS 18在破骨细胞中的表达in vivo.Conclusions：RGS 18作为酸中毒诱导的破骨细胞生成OGR 1/NFAT信号通路的负调节剂，RANKL通过抑制RGS 18的表达刺激破骨细胞生成。因此，研究结果表明，破骨细胞生成的RGS蛋白的一种新的控制机制。
Introduction: Osteoclasts are bone-resorbing multinuclear giant cells that are differentiated from mononuclear macrophage/monocyte lineage precursors stimulated by the RANK/RANKL system. The regulators of G-protein signaling (RGS) family is a diverse group of proteins that accelerate intrinsic GTP hydrolysis on heterotrimeric G-protein alpha subunits and play crucial roles in physiological regulation of G-protein-mediated cell signaling in various tissues and organs. We examined the expression and function of RGS18, a myeloid lineage-specific RGS protein, during osteoclastogenesis.Materials and Methods: A macrophage/monocyte lineage cell line, RAW264.7, and primary osteoclast precursor monocytes derived from mouse bone marrow cultured with macrophage-colony stimulating factor (M-CSF) (bone marrow-derived monocytes [BMMs]) were used in this study. Both cell types differentiate into osteoclast-like cells on activation by RANKL. Expression of different RGS proteins, including RGS18, was assessed by gene-specific RT-PCR. The subcellular distribution of IZGS18 on native osteoclasts in bone tissues, as well as in RAW264.7 cells, was examined by immunohistochemistry using a specific polyclonal antibody. Short interfering RNA against RGS18 was used to inhibit the function endogenous RGS18 in these cell types. Activation of NFATc1, an osteoclastogenic transcription factor, on external acidosis was assessed by visualizing the nuclear localization of NFATc1 visualized with anti-NFATc1 antibody.Results: RAW264.7 and BMM cells both expressed mRNA for 10 different mammalian RGS proteins, including RGS18. Expression of RGS18 is significantly inhibited by RANKL both cell types, and inhibition of RGS18 function using RNA interference prominently enhanced osteoclastogenesis on stimulation with RANKL. The effect of RGS18 inhibition was reversed by blocking of proton-sensing OGR1 signaling, and overexpression of exogenous RGS18 inhibited extracellular acidosis-mediated NFATc1 activation. Immunohistochemical studies of mouse bone tissues revealed expression of RGS18 in osteoclasts in vivo.Conclusions: RGS18 acts as a negative regulator of the acidosis-induced osteoclastogenic OGR1/NFAT signaling pathway, and RANKL stimulates osteoclastogenesis by inhibiting expression of RGS18. Therefore, the results suggest a novel control mechanism of osteoclastogenesis by RGS proteins.