Costa-Casnellie M R, Cragoe E J, Segel G B, Lichtman M A
Department of Medicine, University of Rochester, New York 14642.
J Cell Physiol. 1989 Nov;141(2):294-300. doi: 10.1002/jcp.1041410210.
Activation of neutrophils leading to superoxide production is accompanied by cytoplasmic alkalinization, which results from stimulation of the Na+/H+ exchanger. Since the exchanger undergoes permanent alterations during neutrophilic maturation of HL-60 cells (Costa-Casnellie et al.: Journal of Biological Chemistry 263:11851-11855, 1988), we investigated whether its response to external stimuli such as phorbol esters or osmotic shock also was modified during cell maturation. Mature HL-60 cells produce superoxide in response to active phorbol esters, whereas immature HL-60 cells do not. Stimulation of the exchanger by active phorbol esters (phorbol 12-myristate 13-acetate or phorbol 12,13-dibutyrate) was observed in mature neutrophilic HL-60 cells but not in their immature counterparts. Inactive 4-alpha phorbol had no effect in either cell population. Compound H7 inhibited phorbol ester activation by 65%. In mature neutrophilic cells activation of the exchanger by phorbol esters caused two novel changes of its properties: 1) its apparent Km for Na+ transport increased 2-fold; 2) its Vmax increased 2.6-fold. Phorbol esters also caused a shift in pH dependence of activation similar to that induced in other cells. Osmotic shock, a different method known to activate the exchanger of other cells, induced activation in mature neutrophilic cells but not in immature cells. Thus, the response of the exchanger to external stimuli is affected by alterations occurring in association with cell maturation.
中性粒细胞的激活导致超氧化物的产生，同时伴有细胞质碱化，这是由Na+/H+交换体的刺激引起的。由于该交换体在HL-60细胞嗜中性成熟过程中会发生永久性改变（科斯塔-卡斯内利等人：《生物化学杂志》263:11851-11855，1988年），我们研究了其在细胞成熟过程中对佛波酯或渗透压休克等外部刺激的反应是否也发生了改变。成熟的HL-60细胞对活性佛波酯有反应产生超氧化物，而未成熟的HL-60细胞则没有。在成熟的嗜中性HL-60细胞中观察到活性佛波酯（佛波醇12-肉豆蔻酸酯13-乙酸酯或佛波醇12,13-二丁酸酯）对交换体的刺激，而在未成熟的对应细胞中则未观察到。无活性的4-α佛波醇对两种细胞群体均无影响。化合物H7可使佛波酯激活作用降低65%。在成熟的嗜中性细胞中，佛波酯对交换体的激活导致其性质发生两个新变化：1）其Na+转运的表观Km增加了2倍；2）其Vmax增加了2.6倍。佛波酯还导致激活的pH依赖性发生变化，类似于在其他细胞中诱导的变化。渗透压休克是已知的激活其他细胞交换体的另一种方法，它能诱导成熟的嗜中性细胞激活，但不能诱导未成熟细胞激活。因此，交换体对外部刺激的反应受与细胞成熟相关的改变的影响。
