Cytosolic acidification and lysosomal alkalinization during TNF-α induced apoptosis in U937 cells
Cytosolic acidification and lysosomal alkalinization during TNF-α induced apoptosis in U937 cells
复制标题
DOI：
10.1007/s10495-006-7108-5
复制
发表时间：
2006-07-01
期刊：
影响因子：
7.2
通讯作者：
Öllinger, K
中科院分区：
文献类型：
--
作者：
Nilsson, C;Johansson, U;Öllinger, K
细胞凋亡通常与细胞质酸化有关，由于溶酶体质子梯度的丧失和溶酶体内容物的释放是细胞凋亡的早期事件，我们研究了溶酶体室是否有助于细胞质酸化。U937细胞暴露于肿瘤坏死因子α后，3个群体；流式细胞术检测健康细胞、凋亡前细胞和凋亡细胞。研究人员对这些人群进行了细胞内pH值和凋亡相关事件的调查。健康细胞的胞质pH从7.2 +/- 0.1下降到凋亡前caspase阴性细胞的6.8 +/- 0.1。在凋亡的caspase阳性细胞中，pH进一步降低至5.7 +/- 0.04。添加针对半胱天冬酶或线粒体f0f1 - atp酶的特异性抑制剂不影响胞质酸化。在细胞质酸化的同时，检测到溶酶体pH值从健康群体的4.3 +/- 0.3分别上升到凋亡前和凋亡群体的4.8 +/- 0.3和5.5 +/- 0.3。此外，在凋亡前和凋亡细胞中，溶酶体向胞浆释放组织蛋白酶D检测到溶酶体膜通透性增加。因此，我们认为溶酶体质子释放是暴露于tnf - α的U937细胞胞质酸化的原因。
Apoptosis is often associated with acidification of the cytosol and since loss of lysosomal proton gradient and release of lysosomal content are early events during apoptosis, we investigated if the lysosomal compartment could contribute to cytosolic acidification. After exposure of U937 cells to tumor necrosis factor-alpha, three populations; healthy, pre-apoptotic, and apoptotic cells, were identified by flow cytometry. These populations were investigated regarding intra-cellular pH and apoptosis-associated events. There was a drop in cytosolic pH from 7.2 +/- 0.1 in healthy cells to 6.8 +/- 0.1 in pre-apoptotic, caspase-negative cells. In apoptotic, caspase-positive cells, the pH was further decreased to 5.7 +/- 0.04. The cytosolic acidification was not affected by addition of specific inhibitors towards caspases or the mitochondrial F0F1-ATPase. In parallel to the cytosolic acidification, a rise in lysosomal pH from 4.3 +/- 0.3, in the healthy population, to 4.8 +/- 0.3 and 5.5 +/- 0.3 in the pre-apoptotic- and apoptotic populations, respectively, was detected. In addition, lysosomal membrane permeability increased as detected as release of cathepsin D from lysosomes to the cytosol in pre-apoptotic and apoptotic cells. We, thus, suggest that lysosomal proton release is the cause of the cytosolic acidification of U937 cells exposed to TNF-alpha.