Expression of a P2X7 receptor by a subpopulation of human osteoblasts
Expression of a P2X7 receptor by a subpopulation of human osteoblasts
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DOI：
10.1359/jbmr.2001.16.5.846
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发表时间：
2001-05-01
影响因子：
6.2
通讯作者：
Bowler, WB
中科院分区：
文献类型：
--
作者：
Gartland, A;Hipskind, RA;Bowler, WB
现在有确凿的证据表明，细胞外核苷酸通过告诉表面P2受体的作用是重要的骨细胞功能的局部调节剂。P2受体的多种亚型已经定位于骨，其中它们的活化调节多个过程，包括成骨细胞增殖、成骨细胞介导的骨形成以及破骨细胞形成和再吸收能力。局部释放的核苷酸也已经显示出使周围细胞对全身性因子如甲状旁腺激素（PTH）的作用敏感。在非骨骼组织中，最近的注意力集中在一种特殊的P2受体，P2 X（7）受体（以前称为P2 Z），以及其在长时间刺激下在质膜中形成非选择性水孔的能力。该受体的表达最初被认为仅限于造血来源的细胞，其中它与细胞融合、凋亡和促炎细胞因子的释放有关。然而，最近的报道表明该受体在基质来源的细胞中表达。在这项研究中，我们研究了P2 X（7）受体在两个人骨肉瘤细胞系中的表达，以及在信使RNA（mRNA）和蛋白质水平上的几个群体的原代人骨源性细胞（HBDC）。我们发现有一个成骨细胞亚群表达P2 X（7）受体，并且通过监测孔形成后溴化乙锭的摄取来评估这些受体的功能。非特异性P2 X受体拮抗剂PPADS对特异性激动剂2 '，3'-（4-苯甲酰基）-苯甲酰基-腺苷三磷酸（BzATP）引起的延迟乳酸脱氢酶（LDH）释放的抑制证实了受体介导的事件。用BzATP处理后，SaOS-2细胞表现出与P2 X（7）介导的造血细胞凋亡后观察到的一致的显著形态学变化。末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸-生物素缺口末端标记（TUNEL）和P2 X（7）特异性单克隆抗体的双重染色证实了表达P2 X（7）受体的成骨细胞的凋亡诱导。这些数据首次表明成骨细胞亚群中功能性P2 X（7）受体的表达，其激活可导致ATP介导的凋亡。
There is now conclusive evidence that extracellular nucleotides acting via tell surface P2 receptors are important local modulators of bone cell function. Multiple subtypes of P2 receptors have been localized to bone, where their activation modulates multiple processes including osteoblast proliferation, osteoblast-mediated bone formation, and osteoclast formation and resorptive capacity, Locally released nucleotides also have been shown to sensitize surrounding cells to the action of systemic factors such as parathyroid hormone (PTH). In nonskeletal tissue recent attention has focused on one particular P2 receptor, the P2X(7) receptor (previously termed P2Z), and its ability to form nonselective aqueous pores in the plasma membrane on prolonged stimulation. Expression of this receptor originally was thought to be restricted to cells of hemopoietic origin, in which it has been implicated in cell fusion, apoptosis, and release of proinflammatory cytokines, However, recent reports have indicated expression of this receptor in cells of stromal origin. In this study, we investigated the expression of the P2X(7) receptor in two human osteosarcoma cell lines, as well as several populations of primary human bone-derived cells (HBDCs) at the levels of messenger RNA (mRNA) and protein. We found that there is a subpopulation of osteoblasts that expresses the P2X(7) receptor and that these receptors are functional as assessed by monitoring ethidium bromide uptake following pore formation. Inhibition of delayed lactate dehydrogenase (LDH) release in response to the specific agonist 2 ' ,3 '-(4-benzoyl)-benzoyl-adenosine triphosphate (BzATP) by the nonspecific P2X receptor antagonist PPADS confirmed a receptor-mediated event, After treatment with BzATP SaOS-2 cells exhibited dramatic morphological changes consistent with those observed after P2X(7)-mediated apoptosis in hemopoietic cells. Dual staining with terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) and a P2X(7)-specific monoclonal antibody confirmed the induction of apoptosis in osteoblasts expressing the P2X(7) receptor, These data show for the first time the expression of functional P2X(7) receptors in a subpopulation of osteoblasts, activation of which can result in ATP-mediated apoptosis.