Mutants of glucokinase cause hypoglycaemia- and hyperglycaemia syndromes and their analysis illuminates fundamental quantitative concepts of glucose homeostasis
Mutants of glucokinase cause hypoglycaemia- and hyperglycaemia syndromes and their analysis illuminates fundamental quantitative concepts of glucose homeostasis
复制标题
DOI：
10.1007/s001250051289
复制
发表时间：
1999-10-01
期刊：
影响因子：
8.2
通讯作者：
Matschinsky, FM
中科院分区：
文献类型：
--
作者：
Davis, EA;Cuesta-Muñoz, A;Matschinsky, FM
目的/假设。葡萄糖激酶基因突变可引起高血糖或低血糖。对这些与葡萄糖激酶基因相关的葡萄糖稳态缺陷缺乏定量的了解。因此，开发了葡萄糖激酶的野生型和20种错义突变体的动力学变量的数据库，并用于数学建模以预测葡萄糖刺激的胰岛素释放的阈值。重组人葡萄糖激酶在E.杆菌测定了葡萄糖激酶的K（cat）、葡萄糖S-0.5、ATP K_m和Hill数。抑制硬脂酰辅酶A和葡萄糖激酶调节蛋白和热稳定性进行了测定的所有突变体动力学类似于野生型葡萄糖激酶。建立了预测葡萄糖刺激胰岛素释放阈值的数学模型。该模型基于葡萄糖激酶的双底物动力学和数据库中的动力学变量。假设两个葡萄糖激酶基因等位基因在β细胞中同等表达，并且葡萄糖激酶的诱导作为基础血糖的函数发生。大的变化，突变体之间的差异很大，发现几乎所有的变量。葡萄糖刺激的胰岛素释放阈值的葡萄糖激酶通量约为正常β细胞中总磷酸化潜力的25%，这被用于预测突变杂合子的阈值。与葡萄糖激酶基因相关的年轻型成熟型糖尿病和与葡萄糖激酶基因相关的家族性高胰岛素血症性低血糖的临床数据以及本研究的葡萄糖激酶动力学数据用于测试模型。该模型预测这些病例的空腹血糖在3和7 mmol/l之间。结论/解释。建立了葡萄糖激酶野生型和20种突变体的动力学数据库。许多动力学差异被发现的突变体。计算葡萄糖刺激胰岛素释放阈值的数学模型预测葡萄糖激酶基因突变受试者的空腹血糖在3 - 7 mmol/l之间。
Aims/hypothesis. Mutations of the glucokinase gene cause hyperglycaemia or hypoglycaemia. A quantitative understanding of these defects of glucose homeostasis linked to the glucokinase gene was lacking. Therefore a database of kinetic variables of wild-type and 20 missense mutants of glucokinase was developed and used in mathematical modelling to predict the thresholds for glucose-stimulated insulin release.Methods. Recombinant human glucokinase was generated in E. coli. The k(cat), glucose S-0.5, ATP K-m, and Hill number of glucokinase were determined. Inhibition by Stearoyl CoA and glucokinase regulatory protein and thermal stability were assayed for all mutants kinetically similar to wild-type glucokinase. A mathematical model predicting the threshold for glucose-stimulated insulin release was constructed. This model is based on the two substrate kinetics of glucokinase and the kinetic variables of the database. It is assumed that both glucokinase gene alleles are equally expressed in beta-cells and that induction of glucokinase occurs as a function of basal blood glucose.Results. Large changes, varying greatly between mutants were found in nearly all variables. Glucokinase flux at threshold for glucose-stimulated insulin release was about 25% of total phosphorylating potential in the normal beta-cell and this was used to predict thresholds for the mutant heterozygotes. Clinical data for maturity onset diabetes of the young type linked to the glucokinase gene and familial hyperinsulinaemic hypoglycaemia linked to the glucokinase gene and the glucokinase kinetic data of this study were used to test the model. The model predicts fasting blood glucose between 3 and 7 mmol/l in these cases.Conclusion/interpretation. A kinetics database of wild-type and 20 mutants of glucokinase was developed. Many kinetic differences were found for the mutants. The mathematical model to calculate the threshold for glucose-stimulated insulin release predicts fasting blood glucose between 3 and 7 mmol/l in subjects with glucokinase gene mutations.