Jamieson G P, Snook M B, Thurlow P J, Wiley J S
Department of Haematology, Austin Campus, Heidelberg, Victoria, Australia.
J Cell Physiol. 1996 Mar;166(3):637-42. doi: 10.1002/(SICI)1097-4652(199603)166:3<637::AID-JCP19>3.0.CO;2-3.
Lymphocytes from normal subjects or patients with chronic lymphocytic leukemia are known to possess receptors for extracellular ATP termed P2Z purinoceptors whose physiological role is undefined. Addition of extracellular ATP (50-500 microM) to both normal and leukemic lymphocytes caused loss of binding of monoclonal antibodies to L-selectin (CD62L) on the cell surface. UTP, ADP, and adenosine (all at 500 microM) had no effect on L-selectin expression. Several features of the ATP-induced loss of L selectin indicate that this effect is mediated by lymphocyte P2Z purinoceptors. First the loss was attenuated in isotonic NaCl medium compared to 150 mM KCl medium. Second the loss of L-selectin was immediately halted by addition of Mg2+ ions in molar excess of ATP. The most potent nucleotide causing L-selectin loss was benzoylbenzoic ATP (> 10 microM) which is also the most potent agonist for the P2Z purinoceptor. Finally preincubation of lymphocytes with oxidized ATP, an irreversible inhibitor of P2Z purinoceptors, also inhibited ATP induced loss of L-selectin. Extracellular ATP is known to open an ion channel associated with the P2Z purinoceptor on B-lymphocytes which allows influx of Ca2+. However, ATP-induced loss of L-selectin did not require extracellular Ca2+. Moreover addition of the calcium ionophore, ionomycin, had minimal effect on L-selectin expression. Staurosporine (500 nM), an inhibitor of protein kinase C, inhibited only 10% of ATP induced loss of L-selectin but completely inhibited the loss of L-selectin caused by 50 nM PMA. Thus extracellular ATP interacts with lymphocyte P2Z purinoceptors which leads to shedding of L-selectin via a pathway which requires neither Ca2+ influx nor activation of protein kinase C. ATP may have a physiological role in the loss of L-selectin which occurs during the interactions of lymphocytes with other cells.
已知来自正常受试者或慢性淋巴细胞白血病患者的淋巴细胞拥有针对细胞外ATP的受体，称为P2Z嘌呤受体，其生理作用尚不清楚。向正常和白血病淋巴细胞中添加细胞外ATP（50 - 500微摩尔）会导致单克隆抗体与细胞表面L-选择素（CD62L）的结合丧失。UTP、ADP和腺苷（均为500微摩尔）对L-选择素表达没有影响。ATP诱导的L-选择素丧失的几个特征表明，这种效应是由淋巴细胞P2Z嘌呤受体介导的。首先，与150 mM KCl培养基相比，在等渗NaCl培养基中丧失减弱。其次，通过添加摩尔过量于ATP的Mg2+离子，L-选择素的丧失立即停止。导致L-选择素丧失的最有效核苷酸是苯甲酰苯甲酸ATP（> 10微摩尔），它也是P2Z嘌呤受体最有效的激动剂。最后，用氧化ATP（P2Z嘌呤受体的不可逆抑制剂）预孵育淋巴细胞，也抑制了ATP诱导的L-选择素丧失。已知细胞外ATP会打开与B淋巴细胞上P2Z嘌呤受体相关的离子通道，允许Ca2+内流。然而，ATP诱导的L-选择素丧失不需要细胞外Ca2+。此外，添加钙离子载体离子霉素对L-选择素表达的影响最小。蛋白激酶C抑制剂星形孢菌素（500 nM）仅抑制ATP诱导的L-选择素丧失的10%，但完全抑制了50 nM佛波酯引起的L-选择素丧失。因此，细胞外ATP与淋巴细胞P2Z嘌呤受体相互作用，通过既不需要Ca2+内流也不需要蛋白激酶C激活的途径导致L-选择素脱落。ATP可能在淋巴细胞与其他细胞相互作用期间发生的L-选择素丧失中具有生理作用。
