A NOVEL FUNCTION OF GLUTAMINE IN CELL-CULTURE - UTILIZATION OF GLUTAMINE FOR THE UPTAKE OF CYSTINE IN HUMAN-FIBROBLASTS
A NOVEL FUNCTION OF GLUTAMINE IN CELL-CULTURE - UTILIZATION OF GLUTAMINE FOR THE UPTAKE OF CYSTINE IN HUMAN-FIBROBLASTS
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DOI：
10.1002/jcp.1041370221
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发表时间：
1988-11-01
影响因子：
5.6
通讯作者：
ISHII, T
中科院分区：
文献类型：
--
作者：
BANNAI, S;ISHII, T
在人二倍体成纤维细胞IMR-90中研究了谷氨酰胺的转运和代谢。谷氨酰胺通过系统ASC（Na+依赖性氨基酸转运系统，尤其是与短链或极性侧链氨基酸反应）摄取。在常规培养基中，细胞含有大量谷氨酸，其主要来源是培养基中的谷氨酰胺。以前我们描述了一种转运系统，它介导胱氨酸的进入以交换谷氨酸的排出（Bannai，1986）。由于吸收的胱氨酸被还原为半胱氨酸，并且半胱氨酸容易离开培养基，在那里它被氧化为胱氨酸，因此已经假设了跨质膜的胱氨酸-半胱氨酸循环。当细胞在无谷氨酸/谷氨酰胺的培养基中培养时，细胞内谷氨酸减少，这取决于培养基中胱氨酸的量;在没有胱氨酸的情况下，谷氨酸减少非常缓慢。当细胞在普通培养基中培养时，培养基中谷氨酰胺减少，而谷氨酸增加。这两种变化都与培养基中胱氨酸浓度密切相关。这些结果与细胞内谷氨酸（其来源是培养基中的谷氨酰胺）从细胞释放到培养基中以摄取胱氨酸并由此旋转胱氨酸-半胱氨酸循环的观点一致。在常规培养中，谷氨酰胺总消耗量的三分之一到二分之一似乎用于摄取胱氨酸。
Transport and metabolism of glutamine has been investigated in human diploid fibroblasts, IMR-90. Glutamine was taken up via System ASC (Na+-dependent amino acid transport system especially reactive with short or polar side chain amino acids). In the routine culture medium the cells contained a large quantity of glutamate; its major source was shown to be glutamine in the medium. Previously we described a transport system that mediates the entrance of cystine in exchange for the exit of glutamate (Bannai, 1986). Since the cystine taken up is reduced to cysteine and the cysteine readily exits to the medium where it is oxidized to cystine, a cystine-cysteine cycle across the plasma membrane has been postulated. When the cells were cultured in glutamate/glutamine-free medium, intracellular glutamate decreased, depending on the amount of cystine in the medium; in the absence of cystine, glutamate decreased very slowly. When the cells were cultured in ordinary medium, glutamine in the medium decreased, and glutamate in the medium increased. Both changes were well correlated with cystine concentration in the medium. These results are consistent with the view that the intracellular glutamate, of which the source is glutamine in the medium, is released from the cells into the medium in order to take up cystine and thereby to rotate the cystine-cysteine cycle. In the routine culture one-third to one-half of the total consumption of glutamine seems to be used for the uptake of cystine.