Lysosomal alkalinization, lipid oxidation, and reduced phagosome clearance triggered by activation of the P2X7 receptor
Lysosomal alkalinization, lipid oxidation, and reduced phagosome clearance triggered by activation of the P2X7 receptor
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DOI：
10.1096/fj.13-236166
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发表时间：
2013-11-01
期刊：
影响因子：
4.8
通讯作者：
Mitchell, Claire H.
中科院分区：
文献类型：
--
作者：
Guha, Sonia;Baltazar, Gabriel C.;Mitchell, Claire H.
溶酶体酶在低pH下最佳地起作用;由于废物的积累有助于细胞老化和疾病，溶酶体pH的失调可能代表几种病理学的早期步骤。在这里，我们表明，刺激P2 X7受体（P2 X7 R）ATP碱化溶酶体在培养的人视网膜色素上皮（RPE）细胞和损害溶酶体功能。0.3U P2 X7 R刺激不能杀死RPE细胞，但可使溶酶体碱化。受体刺激也升高胞浆Ca 2 +; Ca 2+内流是必要的，但不足以溶酶体碱化。P2 X7 R刺激减少了对组织蛋白酶D活性位点的接近。有趣的是，溶酶体碱化伴随着P2 X7 R拮抗作用阻止的脂质氧化的增加。同样，吞噬的感光细胞外节增加溶酶体碱化的自发荧光恢复73%的P2 X7 R拮抗剂。总之，这表明P2 X7 R的内源性自身刺激可能氧化脂质并阻碍清除。P2 X7 R在小鼠RPE的顶膜和基底膜上表达; P2 X7 R和细胞外ATP标记物NTPDase 1的mRNA表达在来自Stargardt视网膜变性的ABCA 4（-/-）小鼠模型的RPE组织中升高。总之，P2 X7 R刺激升高溶酶体pH并阻碍溶酶体功能，表明过度刺激在累积疾病中的可能作用。巴尔塔扎尔湾C.的方法，科菲，E. E、图湖一、Lim，J.C.，Beckel，J. M.，帕特尔，S.，Eysteinsson，T.，卢伟，O'Brien-Jenkins，A.，拉提斯，A. M.，米切尔角，澳-地H. P2 X7受体激活引发的溶酶体碱化、脂质氧化和吞噬体清除率降低。
Lysosomal enzymes function optimally at low pH; as accumulation of waste material contributes to cell aging and disease, dysregulation of lysosomal pH may represent an early step in several pathologies. Here, we demonstrate that stimulation of the P2X7 receptor (P2X7R) for ATP alkalinizes lysosomes in cultured human retinal pigmented epithelial (RPE) cells and impairs lysosomal function. P2X7R stimulation did not kill RPE cells but alkalinized lysosomes by 0.3 U. Receptor stimulation also elevated cytoplasmic Ca2+; Ca2+ influx was necessary but not sufficient for lysosomal alkalinization. P2X7R stimulation decreased access to the active site of cathepsin D. Interestingly, lysosomal alkalinization was accompanied by a rise in lipid oxidation that was prevented by P2X7R antagonism. Likewise, the autofluorescence of phagocytosed photoreceptor outer segments increased by lysosomal alkalinization was restored 73% by a P2X7R antagonist. Together, this suggests that endogenous autostimulation of the P2X7R may oxidize lipids and impede clearance. The P2X7R was expressed on apical and basolateral membranes of mouse RPE; mRNA expression of P2X7R and extracellular ATP marker NTPDase1 was raised in RPE tissue from the ABCA4(-/-) mouse model of Stargardt's retinal degeneration. In summary, P2X7R stimulation raises lysosomal pH and impedes lysosomal function, suggesting a possible role for overstimulation in diseases of accumulation.Guha, S., Baltazar G. C., Coffey, E. E., Tu, L.-A., Lim, J. C., Beckel, J. M., Patel, S., Eysteinsson, T., Lu, W., O'Brien-Jenkins, A., Laties, A. M., Mitchell, C. H. Lysosomal alkalinization, lipid oxidation, and reduced phagosome clearance triggered by activation of the P2X7 receptor.