Sanders M M, Kon C
Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854.
J Cell Physiol. 1991 Jan;146(1):180-90. doi: 10.1002/jcp.1041460123.
We have investigated the effects of extracellular anions on the regulation of expression of the heat shock response in Drosophila Kc cells incubated in defined balanced salt solutions. Widely varying chloride concentrations had no effect on normal or heat shock protein (hsp) expression. Increasing glutamate concentrations from zero to 15 mM increased hsp expression more than 100-fold while affecting expression of non-heat-shock proteins minimally. Glutamine was 20-100-fold more potent than glutamate in supporting hsp expression, while other amino acids were less effective or supported no detectable hsp synthesis in heat shock. Inhibition of glutamine synthetase with methionine-sulfoximine resulted in very low hsp expression with glutamate and normal high level expression with glutamine, confirming the importance of glutamine. The absence of glucose and treatment with 2-deoxyglucose did not change the requirement for adequate glutamine for hsp expression. Cells heat shocked under conditions which gave very low hsp expression resumed growth when returned to normal medium as well as cells which expressed normal levels of hsps. Measurements of free amino acid levels in cells heat shocked in the presence and absence of glutamine showed a correlation between glutamine levels and amount of hsp expression. We conclude that a physiological process regulated by glutamine or a glutamine metabolite is important for normal hsp expression in heat shock conditions in Drosophila.
我们研究了细胞外阴离子对在特定平衡盐溶液中培养的果蝇Kc细胞热休克反应表达调控的影响。广泛变化的氯化物浓度对正常或热休克蛋白（hsp）表达没有影响。将谷氨酸浓度从零增加到15 mM可使hsp表达增加100倍以上，而对非热休克蛋白表达的影响最小。谷氨酰胺在支持hsp表达方面比谷氨酸强20 - 100倍，而其他氨基酸效果较差或在热休克中不支持可检测到的hsp合成。用甲硫氨酸亚砜亚胺抑制谷氨酰胺合成酶会导致在有谷氨酸时hsp表达非常低，而在有谷氨酰胺时表达正常高水平，证实了谷氨酰胺的重要性。葡萄糖的缺失和用2 - 脱氧葡萄糖处理并没有改变hsp表达对充足谷氨酰胺的需求。在给予非常低hsp表达的条件下热休克的细胞，当回到正常培养基时恢复生长，表达正常水平hsp的细胞也是如此。对在有和没有谷氨酰胺的情况下热休克的细胞中游离氨基酸水平的测量表明，谷氨酰胺水平与hsp表达量之间存在相关性。我们得出结论，由谷氨酰胺或谷氨酰胺代谢物调节的生理过程对于果蝇热休克条件下的正常hsp表达很重要。
