Brisseau G F, Grinstein S, Hackam D J, Nordström T, Manolson M F, Khine A A, Rotstein O D
Department of Surgery, Toronto Hospital, Ontario, Canada.
J Biol Chem. 1996 Jan 26;271(4):2005-11. doi: 10.1074/jbc.271.4.2005.
Maintenance of cytoplasmic pH (pHi) within a narrow physiological range is crucial to normal cellular function. This is of particular relevance to phagocytic cells within the acidic inflammatory microenvironment where the pHi tends to be acid loaded. We have previously reported that a vacuolar-type H(+)-ATPase (V-ATPase) situated in the plasma membrane of macrophages and poised to extrude protons from the cytoplasmic to the extracellular space is an important pHi regulatory mechanism within the inflammatory milieu. Since this microenvironment is frequently characterized by the influx of cells known to release inflammatory cytokines, we performed studies to examine the effect of one such mediator molecule, interleukin-1 (IL-1), on pHi regulation in peritoneal macrophages. IL-1 caused a time- and dose-dependent increase in macrophage pHi recovery from an acute acid load. This effect was specific to IL-1 and was due to enhanced plasmalemmal V-ATPase activity. The increased V-ATPase activity by IL-1 occurred following a lag period of several hours and required de novo protein and mRNA synthesis. However, Northern blot analysis revealed that IL-1 did not exert its effect via alterations in the levels of mRNA transcripts for the A or B subunits of the V-ATPase complex. Finally, stimulation of both cAMP-dependent protein kinase and protein kinase C was required for the stimulatory effect of IL-1 on V-ATPase activity. Thus, cytokines present within the inflammatory milieu are able to modulate pHi regulatory mechanisms. These data may represent a novel mechanism whereby cytokines may improve cellular function at inflammatory sites.
将细胞质pH值（pHi）维持在狭窄的生理范围内对正常细胞功能至关重要。这对于酸性炎症微环境中的吞噬细胞尤为重要，在该微环境中pHi往往会被酸负荷。我们之前报道过，位于巨噬细胞质膜上、准备将质子从细胞质挤出到细胞外空间的液泡型H(+)-ATP酶（V-ATP酶）是炎症环境中一种重要的pHi调节机制。由于这种微环境的特点通常是已知会释放炎性细胞因子的细胞流入，我们进行了研究，以检查一种这样的介质分子——白细胞介素-1（IL-1）对腹膜巨噬细胞中pHi调节的影响。IL-1导致巨噬细胞从急性酸负荷中恢复时pHi呈时间和剂量依赖性增加。这种效应是IL-1特有的，并且是由于质膜V-ATP酶活性增强所致。IL-1使V-ATP酶活性增加发生在几个小时的延迟期之后，并且需要从头合成蛋白质和mRNA。然而，Northern印迹分析显示，IL-1并非通过改变V-ATP酶复合物A或B亚基的mRNA转录水平来发挥其作用。最后，IL-1对V-ATP酶活性的刺激作用需要同时激活cAMP依赖性蛋白激酶和蛋白激酶C。因此，炎症环境中存在的细胞因子能够调节pHi调节机制。这些数据可能代表了一种新的机制，通过该机制细胞因子可以改善炎症部位的细胞功能。
