Mice with Whole-Body Disruption of AMPK-Glycogen Binding Have Increased Adiposity, Reduced Fat Oxidation and Altered Tissue Glycogen Dynamics.

ABSTRACT

The AMP-activated protein kinase (AMPK), a central regulator of cellular energy balance and metabolism, binds glycogen via its ß subunit. However, the physiological effects of disrupting AMPK-glycogen interactions remain incompletely understood. To chronically disrupt AMPK-glycogen binding, AMPK ß double knock-in (DKI) mice were generated with mutations in residues critical for glycogen binding in both the ß1 (W100A) and ß2 (W98A) subunit isoforms. We examined the effects of this DKI mutation on whole-body substrate utilization, glucose homeostasis, and tissue glycogen dynamics. Body composition, metabolic caging, glucose and insulin tolerance, serum hormone and lipid profiles, and tissue glycogen and protein content were analyzed in chow-fed male DKI and age-matched wild-type (WT) mice. DKI mice displayed increased whole-body fat mass and glucose intolerance associated with reduced fat oxidation relative to WT. DKI mice had reduced liver glycogen content in the fed state concomitant with increased utilization and no repletion of skeletal muscle glycogen in response to fasting and refeeding, respectively, despite similar glycogen-associated protein content relative to WT. DKI liver and skeletal muscle displayed reductions in AMPK protein content versus WT. These findings identify phenotypic effects of the AMPK DKI mutation on whole-body metabolism and tissue AMPK content and glycogen dynamics.