Dobson C B, Day J P, King S J, Itzhaki R F
Department of Optometry and Vision Sciences, University of Manchester Institute of Science and Technology, Manchester, M20 1QD, United Kingdom.
Toxicol Appl Pharmacol. 1998 Sep;152(1):145-52. doi: 10.1006/taap.1998.8489.
The subcellular location of aluminium is unknown, probably because of difficulties in investigating aluminium biochemistry and the use of varied experimental approaches of uncertain sensitivity. We have studied levels of uptake and the localization of gallium and of aluminium in cultured human neuroblastoma cells treated with soluble metal complexes (mainly Al- or Ga-EDTA), radiolabeled with 26Al or 67Ga, respectively. Crude nuclei and cytoplasm were obtained by two separate methods, and DNA, RNA, and proteins were prepared from the nuclei by centrifugation in high salt; also, cytosol and noncytosol were separated using a nondissociating method. Levels of uptake were of similar order for the two metals-on average about 50 pmol/10(6) cells for aluminium and 120 pmol/10(6) cells for gallium, after 4 to 8 days treatment at 250 microM, and approximately 50 to 70% of the metal was found in the cytosol. About 20% of the aluminium and 10 to 25% of the gallium was associated with nuclear protein. A lower proportion was bound to DNA and to nuclear RNA. In cells treated with gallium-citrate/transferrin mixtures, 30 to 35% of the gallium in the cytosol was bound to protein, at least 35 being loosely bound; the main gallium-associated protein was probably intracellular transferrin. The remaining 65 to 70% of the metal in the cytosol was in low-molecular-weight form, and we suggest that the latter metal could affect structures such as the cytoskeleton and also metabolic processes in the cytoplasm. The similarity in distribution of the two metals supports the use of gallium as a "surrogate" for aluminium, at least in cell culture studies.
铝在亚细胞水平的定位尚不清楚，这可能是由于研究铝生物化学存在困难，以及使用了灵敏度不确定的多种实验方法。我们研究了用可溶性金属络合物（主要是铝或镓的乙二胺四乙酸盐）处理的培养人神经母细胞瘤细胞中镓和铝的摄取水平及定位，细胞分别用26Al或67Ga进行放射性标记。通过两种不同方法获得粗核和细胞质，细胞核中的DNA、RNA和蛋白质通过在高盐溶液中离心制备；此外，使用非解离方法分离胞质溶胶和非胞质溶胶。两种金属的摄取水平大致相同——在250微摩尔浓度下处理4至8天后，铝平均约为50皮摩尔/10(6)个细胞，镓为120皮摩尔/10(6)个细胞，并且约50%至70%的金属存在于胞质溶胶中。约20%的铝和10%至25%的镓与核蛋白结合。与DNA和核RNA结合的比例较低。在用柠檬酸镓/转铁蛋白混合物处理的细胞中，胞质溶胶中30%至35%的镓与蛋白质结合，其中至少35%为松散结合；主要的镓相关蛋白可能是细胞内转铁蛋白。胞质溶胶中其余65%至70%的金属呈低分子量形式，我们认为后一种金属可能会影响诸如细胞骨架等结构以及细胞质中的代谢过程。这两种金属分布的相似性支持至少在细胞培养研究中使用镓作为铝的“替代物”。
