Title: Compound- and fiber type-selective requirement of AMPKy3 for insulin-independent glucose uptake in skeletal muscle
Authors: Rhein, P
Desjardins, EM
Rong, P
Ahwazi, D
Bonhoure, N
Stolte, J
Santos, MD
Ovens, AJ
Ehrlich, AM
Garcia, JLS
Ouyang, Q
Yabut, JM
Membrez, M
Kjolby, M
Jessen, N
Oakhill, JS
Treebak, JT
Maire, P
Scott, JW
Sanders, MJ
Descombes, P
Chen, S
Steinberg, GR
Sakamoto, K
Issue Year: 2021
Publisher ELSEVIER
Abstract Objective: The metabolic master-switch AMP-activated protein kinase (AMPK) mediates insulin-independent glucose uptake in muscle and regulates the metabolic activity of brown and beige adipose tissue (BAT). The regulatory AMPKy3 isoform is uniquely expressed in skeletal muscle and potentially in BAT. Herein, we investigated the role that AMPKy3 plays in mediating skeletal muscle glucose uptake and whole-body glucose clearance in response to small-molecule activators that act on AMPK via distinct mechanisms. We also assessed whether y3 plays a role in adipose thermogenesis and browning. Methods: Global AMPKy3 knockout (KO) mice were generated. A systematic whole-body, tissue, and molecular phenotyping linked to glucose homeostasis was performed in y3 KO and wild-type (WT) mice. Glucose uptake in glycolytic and oxidative skeletal muscle ex vivo as well as blood glucose clearance in response to small molecule AMPK activators that target the nucleotide-binding domain of they subunit (AICAR) and allosteric drug and metabolite (ADaM) site located at the interface of the a and 13 subunit (991, MK-8722) were assessed. Oxygen consumption, thermography, and molecular phenotyping with a 133-adrenergic receptor agonist (CL-316,243) treatment were performed to assess BAT thermogenesis, characteristics, and function. Results: Genetic ablation of y3 did not affect body weight, body composition, physical activity, and parameters associated with glucose homeostasis under chow or high-fat diet. y3 deficiency had no effect on fiber-type composition, mitochondrial content and components, or insulinstimulated glucose uptake in skeletal muscle. Glycolytic muscles in y3 KO mice showed a partial loss of AMPKa2 activity, which was associated with reduced levels of AMPKa2 and 132 subunit isoforms. Notably, y3 deficiency resulted in a selective loss of AICAR-, but not MK-8722-induced blood glucose-lowering in vivo and glucose uptake specifically in glycolytic muscle ex vivo. We detected y3 in BAT and found that it preferentially interacts with a2 and 132. We observed no differences in oxygen consumption, thermogenesis, morphology of BAT and inguinal white adipose tissue (iWAT), or markers of BAT activity between WT and y3 KO mice. Conclusions: These results demonstrate that y3 plays a key role in mediating AICAR- but not ADaM site binding drug-stimulated blood glucose clearance and glucose uptake specifically in glycolytic skeletal muscle. We also showed that y3 is dispensable for 133-adrenergic receptor agonist-induced thermogenesis and browning of iWAT. (c) 2021 The Authors. Published by Elsevier GmbH. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
URI: https://publications.svi.edu.au/publications/8442
Other Identifiers 10.1016/j.molmet.2021.101228
Publication type Article