Pank1 deletion in leptin-deficient mice reduces hyperglycaemia and hyperinsulinaemia and modifies global metabolism without affecting insulin resistance.

ABSTRACT

AIMS/HYPOTHESIS: Pantothenate kinase (PANK) is the first enzyme in CoA biosynthesis. Pank1-deficient mice have 40% lower liver CoA and fasting hypoglycaemia, which results from reduced gluconeogenesis. Single-nucleotide polymorphisms in the human PANK1 gene are associated with insulin levels, suggesting a link between CoA and insulin homeostasis. We determined whether Pank1 deficiency (1) modified insulin levels, (2) ameliorated hyperglycaemia and hyperinsulinaemia, and (3) improved acute glucose and insulin tolerance of leptin (Lep)-deficient mice. METHODS: Serum insulin and responses to glucose and insulin tolerance tests were determined in Pank1-deficient mice. Levels of CoA and regulating enzymes were measured in liver and skeletal muscle of Lep-deficient mice. Double Pank1/Lep-deficient mice were analysed for the diabetes-related phenotype and global metabolism. RESULTS: Pank1-deficient mice had lower serum insulin and improved glucose tolerance and insulin sensitivity compared with wild-type mice. Hepatic and muscle CoA was abnormally high in Lep-deficient mice. Pank1 deletion reduced hepatic CoA but not muscle CoA, reduced serum glucose and insulin, but did not normalise body weight or improve acute glucose tolerance or protein kinase B phosphorylation in Lep-deficient animals. Pank1/Lep double-deficient mice exhibited reduced whole-body metabolism of fatty acids and amino acids and had a greater reliance on carbohydrate use for energy production. CONCLUSIONS/INTERPRETATION: The results indicate that Pank1 deficiency drives a whole-body metabolic adaptation that improves aspects of the diabetic phenotype and uncouples hyperglycaemia and hyperinsulinaemia from obesity in leptin-deficient mice.