Fujiwara Makiko, Ohbori Kenshi, Ohishi Akihiro, Nishida Kentaro, Uozumi Yoshinobu, Nagasawa Kazuki
Department of Environmental Biochemistry, Kyoto Pharmaceutical University.
Biol Pharm Bull. 2017;40(3):375-380. doi: 10.1248/bpb.b16-00887.
P2X7 receptor (P2X7R), a purinergic receptor, is involved in pathophysiological events such as inflammation and cell death, and thus is an attractive target for therapeutic approaches. It is reported that divalent metal cations (DMCs) inhibit P2X7R activation and that there are species differences in their inhibitory effects. To extrapolate the findings in experimental animals to humans, these species differences have to be clarified, but species differences in the sensitivity of P2X7R to DMCs between man and mouse have not been demonstrated. Here we performed direct comparison of the inhibitory effects of DMCs on human and mouse P2X7R activation. Cell lines constitutively expressing human and mouse P2X7R were used, and their P2X7R activation was evaluated as means of YO-PRO-1 dye uptake. MgCl, NiCl, ZnCl, CuCl and CaCl dose-dependently decreased agonist-induced YO-PRO-1 uptake via both human and mouse P2X7Rs. Apparent differences in the inhibitory profiles for NiCl and CaCl between them were found, and the IC values of DMCs were in the order of CaCl>MgCl>NiCl≈ZnCl>CuCl for both human and mouse P2X7Rs. In this study, we demonstrate that human P2X7R exhibits different sensitivity to nickel and calcium compared with the case of the mouse one, while there is no species difference in the sensitivity of their P2X7Rs to magnesium, zinc and copper, suggesting that the effects of magnesium, zinc and copper on P2X7R-associated pathophysiological events in humans might be predicted from those in mice.
P2X7受体（P2X7R）是一种嘌呤能受体，参与炎症和细胞死亡等病理生理过程，因此是治疗方法的一个有吸引力的靶点。据报道，二价金属阳离子（DMCs）可抑制P2X7R的激活，且其抑制作用存在物种差异。为了将实验动物的研究结果外推至人类，必须明确这些物种差异，但人与小鼠之间P2X7R对DMCs敏感性的物种差异尚未得到证实。在此，我们对DMCs对人和小鼠P2X7R激活的抑制作用进行了直接比较。使用了组成性表达人和小鼠P2X7R的细胞系，并通过YO-PRO-1染料摄取来评估其P2X7R的激活情况。MgCl₂、NiCl₂、ZnCl₂、CuCl₂和CaCl₂均通过人和小鼠的P2X7R剂量依赖性地降低激动剂诱导的YO-PRO-1摄取。发现它们之间NiCl₂和CaCl₂的抑制曲线存在明显差异，对于人和小鼠的P2X7R，DMCs的半数抑制浓度（IC）值顺序均为CaCl₂＞MgCl₂＞NiCl₂≈ZnCl₂＞CuCl₂。在本研究中，我们证明，与小鼠相比，人P2X7R对镍和钙表现出不同的敏感性，而它们的P2X7R对镁、锌和铜的敏感性不存在物种差异，这表明镁、锌和铜对人类P2X7R相关病理生理事件的影响可能可从小鼠的情况进行推断。
