We describe the effects of modulating the activities of glucokinase, phosphofructokinase, and phosphoglucomutase on the branching point between sugar degradation and the biosynthesis of sugar nucleotides involved in the production of exopolysaccharide biosynthesis by Lactococcus lactis. This was realized by using a described isogenic L. lactis mutant with reduced enzyme activities or by control...

In type 2 diabetes, glucose phosphorylation, a regulatory step in glucose utilization by skeletal muscle, is impaired. Since glucokinase expression in skeletal muscle of transgenic mice increases glucose phosphorylation, we examined whether such mice counteract the obesity and insulin resistance induced by 12 wk of a high-fat diet. When fed this diet, control mice became obese, whereas transgen...

Exercise training results not only in enhanced insulin sensitivity but also in a reduction in insulin secretion. In this study, we examined the effects of exercise training on the expression of genes potentially related to insulin synthesis and glucose-stimulated insulin release by measuring pancreatic islet proinsulin, glucose-transporter (GLUT2), and glucokinase mRNAs. Female Wistar rats were...

To examine the possible involvement of insulin and glucose in regulation of pancreatic islet gene expression, hyperinsulinemic (insulin infusion 4.1 mU/kg per min) clamps were performed for 12 h in rats at two different levels of glycemia (either 3 or 8 mM). A control group received a saline infusion for 12 h. At the end of the 12-h study period, pancreatic RNA was extracted, proinsulin and amy...

In pancreatic beta-cells, insulin selectively up-regulates the transcription of its own gene and that of the glucokinase gene by signaling through the two isoforms of the insulin receptor, i.e., A-type (Ex11-) and B-type (Ex11+), using different signaling pathways. However, the molecular mechanism(s) that allows the discrete activation of signaling cascades via the two receptor isoforms remains...

The transcription factor Foxa2 is implicated in blood glucose homeostasis. Conditional expression of Foxa2 or its dominant-negative mutant DN-Foxa2 in INS-1 cells reveals that Foxa2 regulates the expression of genes important for glucose sensing in pancreatic beta-cells. Overexpression of Foxa2 results in blunted glucose-stimulated insulin secretion, whereas induction of DN-Foxa2 causes a left ...

The reason(s) for glucose sensitivity in certain cyanobacterial strains is poorly understood. Inactivation of genes encoding the putative sensor kinase Hik31 in Synechocystis sp. strain PCC 6803 resulted in a mutant unable to grow in the presence of D-glucose. Sensitivities to D-glucose, its analogue 2-deoxy-D-glucose, and fructose, were alleviated in mutants in which glcP, encoding the glucose...

Type 2 diabetes is characterized by islet dysfunction resulting in hyperglycemia, which can then lead to further deterioration in islet function. A possible mechanism for hyperglycemia-induced islet dysfunction is the accumulation of advanced glycation end products (AGE). The DBA/2 mouse develops pancreatic islet dysfunction when exposed to a high glucose environment and/or obesity-induced insu...

Glucokinase (EC 2.7.1.2) first appears in the liver of the rat 2 weeks after birth and increases after weaning on to a high-carbohydrate diet. We investigated the hormonal regulation of glucokinase (GK) mRNA in primary cultures of hepatocytes from 10-12-day-old suckling rats. GK mRNA was undetectable in such cells after 48 h of culture in serum-free medium devoid of hormones. Addition of insuli...

The effect of diet on the desaturation of linoleic acid to y-linolenic acid by liver microsomal preparations, on blood glucose and insulin levels, and on activities of glucokinase, hexokinase, pyruvate kinase, and a-glycerophosphate dehydrogenase have been studied. The female rats used in these experiments were maintained on one of the following dietary regimes: (a) fasted, (6) fasted for 96 hr...