Elevated lysosomal pH in Mucolipidosis type IV cells
Elevated lysosomal pH in Mucolipidosis type IV cells
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DOI：
10.1016/s0009-8981(98)00183-1
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发表时间：
1999-02-01
影响因子：
5
通讯作者：
Pagano, RE
中科院分区：
文献类型：
--
作者：
Bach, G;Chen, CS;Pagano, RE
黏脂质沉积症IV型（ML-IV）和其他几种储存性疾病成纤维细胞(Niemann Pick， A型；Niemann Pick， C型；Hunter (MPS II)；法伯)和正常人皮肤成纤维细胞原位测定。用荧光素结合的葡聚糖脉冲标记细胞以标记溶酶体。然后对活细胞进行定量荧光显微镜，测量两种不同激发波长下的荧光比例。图像处理程序用于定量单个溶酶体的荧光。使用适当的标准曲线将比率数据转换为pH的绝对值。除ML-IV细胞外，所有细胞类型的溶酶体pH值在4.3和4.5之间变化，ML-IV细胞的pH值几乎高出一个单位（pH值与5.2相似）。使用吖啶橙（另一种荧光团，其荧光发射依赖于pH）获得了定性相似的结果，排除了ML-IV细胞中存储的分子可能在基于荧光素的pH测量中诱导伪影的可能性。我们得出结论，溶酶体pH值升高是ML-IV细胞所特有的。尽管参与这些分子分解代谢的溶酶体水解酶看起来是正常的，但这种特性即使不是原因，也可能是广谱物质（包括鞘脂、磷脂和酸性粘多糖）积累的重要因素。(C) 1999 Elsevier Science B.V.版权所有
The lysosomal pH in Mucolipidosis type IV (ML-IV) and several other storage disease fibroblasts (Niemann Pick, type A; Niemann Pick, type C; Hunter (MPS II); and Farber) and in normal human skin fibroblasts was determined in situ. Cells were pulse labeled with a fluorescein-conjugated dextran to label the lysosomes. Quantitative fluorescence microscopy was then carried out on living cells to measure the ratio of fluorescence at two different excitation wavelengths. An image processing routine was used to quantify fluorescence from individual lysosomes. Ratiometric data were converted to an absolute value of pH using an appropriate standard curve. Lysosomal pH varied between 4.3 and 4.5 for all the cell types examined except ML-IV cells which was almost one pH unit higher (pH similar to 5.2). Qualitatively similar results were obtained using acridine orange, another fluorophore whose fluorescence emission is pH dependent, ruling out the possibility that the stored molecules in ML-IV cells might induce an artifact in the fluorescein-based pH measurements. We conclude that elevated lysosomal pH is unique to ML-IV cells. This property may be an important factor, if not the cause, for the accumulation of the broad spectrum of substances, including sphingolipids, phospholipids, and acid mucopolysaccharides, even though the lysosomal hydrolases participating in the catabolism of these molecules appear to be normal. (C) 1999 Elsevier Science B.V. All rights reserved.