Hultberg Björn, Hultberg Malin
Institute of Laboratory Medicine, Department of Clinical Chemistry, University Hospital, Lund S-22185, Sweden.
Clin Chim Acta. 2004 Nov;349(1-2):45-52. doi: 10.1016/j.cccn.2004.05.024.
Glutathione is the most abundant nonprotein sulfhydryl-containing compound and constitutes the largest component of the endogenous thiol buffer. Glutathione is known to have multifaceted physiological functions and is a critical factor in protecting organisms against toxicity and disease. Intracellular cysteine concentration is a limiting factor for glutathione synthesis.
In the present study, the metabolism of intra- and extracellular glutathione in HeLa and hepatoma cell cultures is investigated by using different transport inhibitors for cellular uptake of cystine/cysteine.
There exist several ways of cystine/cysteine transport into HeLa and hepatoma cells, and inhibition of them decreased intracellular concentration of cystine/cysteine and in some cases also of glutathione. It was also shown that a large pool of total cell culture glutathione was located extracellularly in both HeLa and hepatoma cell cultures when gamma-glutamyltranspeptidase (GT) activity was inhibited by acivicin (ACI). Furthermore, the addition of thiol-reactive metal ions significantly increased the total amount of glutathione in hepatoma cell cultures during acivicin inhibition. Thus, occasional determinations of extracellular concentrations of glutathione without GT inhibition strongly underestimate the total turnover of glutathione in a cell culture.
This finding has important implications for future research in glutathione metabolism and the understanding of its role in human health and disease.
谷胱甘肽是最丰富的含非蛋白质巯基的化合物，是内源性硫醇缓冲液的最大组成部分。已知谷胱甘肽具有多方面的生理功能，是保护生物体免受毒性和疾病影响的关键因素。细胞内半胱氨酸浓度是谷胱甘肽合成的限制因素。
在本研究中，通过使用不同的转运抑制剂来抑制胱氨酸/半胱氨酸的细胞摄取，研究了HeLa细胞和肝癌细胞培养物中细胞内和细胞外谷胱甘肽的代谢。
胱氨酸/半胱氨酸进入HeLa细胞和肝癌细胞有几种途径，抑制这些途径会降低细胞内胱氨酸/半胱氨酸的浓度，在某些情况下也会降低谷胱甘肽的浓度。还表明，当阿西维辛（ACI）抑制γ-谷氨酰转肽酶（GT）活性时，HeLa细胞和肝癌细胞培养物中大量的总细胞培养谷胱甘肽位于细胞外。此外，在阿西维辛抑制期间，添加硫醇反应性金属离子显著增加了肝癌细胞培养物中谷胱甘肽的总量。因此，在不抑制GT的情况下偶尔测定细胞外谷胱甘肽浓度会严重低估细胞培养物中谷胱甘肽的总周转率。
这一发现对谷胱甘肽代谢的未来研究以及理解其在人类健康和疾病中的作用具有重要意义。
