Phosphofructokinase-1 and fructose bisphosphatase-1 in canine liver andkidney

摘要

In healthy individuals, plasma glucose levels are maintained within a normal range.During fasting, endogenous glucose is released either through glycogenolysis orgluconeogenesis. Gluconeogenesis involves the formation of glucose-6-phosphate from avariety of precursors followed by its subsequent hydrolysis to glucose. Gluconeogenesisoccurs in the liver and the kidney. In order to compare gluconeogenesis in canine liverand kidney, the activity and expression of the rate limiting enzymes that catalyze thefructose-6-phosphate and fructose 1,6-bisphosphate steps, namely, phosphofructokinase-1(PFK-1) (glycolysis) and fructose bisphosphatase-1 (FBP-1) (gluconeogenesis), wereexamined. Healthy male and female beagle dogs aged 1–2 years were euthanized humanely, andsamples of their liver and kidney were obtained for analysis. The levels of PFK-1 andFBP-1 in canine liver and kidney were assessed by enzymatic assays, Western blotting, andRT-qPCR. Enzyme assays showed that, in dogs, the kidney had higher specific activity ofPFK-1 and FBP-1 than the liver. Western blotting and RT-qPCR data demonstrated that of thethree different subunits (PFK-M, PFK-L, and PFK-P) the PFK-1 in canine liver mainlycomprised PFK-L, whereas the PFK-1 in the canine kidney comprised all three subunits. As aresult of these differences in the subunit composition of PFK-1, glucose metabolism mightbe regulated differently in the liver and kidney.