人白血病细胞系P2X7受体的表达及其介导的细胞内钙浓度变化

采用半定量RT-PCR和流式细胞术，在基因和蛋白水平研究了白血病细胞系U937、HL60和Ramos细胞P2X7受体的表达。荧光染料Fura-2／AM负载后，用荧光分光光度计测定P2X7受体激动剂三磷酸腺苷(adenosine 5′-triphosphate，ATP)和苯甲酰苯甲酸ATP(2′，3′-O-(4-benzoyl)benzoyl-ATP，BzATP)刺激前后细胞内钙离子浓度的变化，以确认其功能。结果表明：U937和HL60细胞系表达P2X7受体的mRNA和蛋白，Ramos不表达；在激动剂的刺激下，可引发U937和HL60细胞胞内钙浓度的显著升高，但对Ramos没有作用。当去除胞外钙离子时，ATP和BzATP刺激均不能引起U937和HL60细胞胞内钙离子浓度的升高。提示U937和HL60细胞表达P2X7受体的基因和功能蛋白，Ramos细胞则不表达该受体。

STUDY ON THE EXPRESSION OF P2X7 RECEPTOR AND ITS MEDIATION IN INTRACELLULAR CALCIUM RESPONSE IN HUMAN LEUKEMIC CELL LINES

The expression of ionotropic ATP-gated channel, P2X7 receptor, was studied at mRNA and protein level in human leukemia cell lines (U937, HL60 and Ramos) by semi-quantitative RT-PCR and flow cytometry. In order to confirm whether the expressed P2X7 receptor had biological function, cytosolic Ca2+ was measured using the fluorescent dye Fura-2/AM. Intracellular free Ca2+ concentration (i) increase in these cells induced by extracellular ATP and the more potent and specific agonist, 2',3'-O-(4-Benzoylbenzoyl)-ATP (BzATP), was determined by spectrophotometer. The results showed that expression of P2X7 receptor was founded at both mRNA and protein level in U937 and HL60 cells, but not in Ramos; ATP and BzATP could induce increase in i through ion channel in cells expressing P2X7 receptor (U937 and HL60, not Ramos); Furthermore, i couldn't be increased by ATP and BzATP in U937 and HL60 cells in the absence of extracellular Ca2+ . These results suggested that P2X7 receptor was expressed functionally in U937 and HL60 cells, but not in Ramos cells.