Kang R, Yamada K, Tanaka T, Lu T, Noguchi T
Department of Nutrition and Physiological Chemistry, Osaka University Medical School, Suita.
J Biochem. 1996 Jan;119(1):162-6. doi: 10.1093/oxfordjournals.jbchem.a021203.
Previous studies have suggested that some glycolytic intermediates are involved in the regulation of L-type pyruvate kinase gene expression by carbohydrates such as glucose and fructose. To find such intermediates, we examined the relationship between the levels of L-type pyruvate kinase mRNA and glycolytic metabolites in hepatocytes cultured under various conditions. Of the metabolites, the levels of 3-phosphoglycerate and phosphoenol-pyruvate only increased significantly under conditions under which the expression of the L-type pyruvate kinase gene was stimulated. The level of glucose 6-phosphate, which was reported to be involved in dietary stimulation of this gene expression, was not correlated with the mRNA level since marked accumulation of deoxyglucose 6-phosphate occurring on the addition of deoxyglucose, a nonmetabolizable glucose analog, was not accompanied by an increase in the L-type pyruvate kinase mRNA level. In addition, we found that fructose at a low concentration in the presence of glucose failed to increase the mRNA and metabolite levels in contrast to other reports that the promoter activity of the L-type pyruvate kinase gene is stimulated by this treatment. Thus we propose that 3-phosphoglycerate and/or phosphoenolpyruvate are involved in the carbohydrate regulation of L-type pyruvate kinase gene expression.
先前的研究表明，一些糖酵解中间产物参与了碳水化合物（如葡萄糖和果糖）对L型丙酮酸激酶基因表达的调控。为了找到这些中间产物，我们研究了在各种条件下培养的肝细胞中L型丙酮酸激酶mRNA水平与糖酵解代谢产物之间的关系。在这些代谢产物中，只有3-磷酸甘油酸和磷酸烯醇丙酮酸的水平在L型丙酮酸激酶基因表达受到刺激的条件下显著升高。据报道，6-磷酸葡萄糖参与了该基因表达的饮食刺激，但由于添加不可代谢的葡萄糖类似物脱氧葡萄糖后，6-磷酸脱氧葡萄糖显著积累，而L型丙酮酸激酶mRNA水平并未随之增加，因此6-磷酸葡萄糖水平与mRNA水平不相关。此外，我们发现，与其他报道称这种处理可刺激L型丙酮酸激酶基因的启动子活性相反，在葡萄糖存在的情况下，低浓度的果糖未能增加mRNA和代谢产物水平。因此，我们认为3-磷酸甘油酸和/或磷酸烯醇丙酮酸参与了L型丙酮酸激酶基因表达的碳水化合物调控。
