Common and distinct roles of AMPKγ isoforms in small-molecule activator-stimulated glucose uptake in mouse skeletal muscle - Research Findings

Sep 28, 2026

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Small-molecule AMPK activators targeting the ADaM allosteric site increase insulin-independent glucose uptake in skeletal muscle and reduce glucose in preclinical hyperglycemia models. The regulatory AMPKγ subunit is central to energy sensing, with γ3 required for AMP/ZMP-driven uptake. Using single-nucleus RNA sequencing and inducible AMPKγ1/γ3 knockout mice, the study tests whether γ1 is required for ADaM activator-stimulated glucose uptake. Results show γ1 is ubiquitous, γ3 enriched in glycolytic myofibers, and both AICAR and MK-8722 responses differ by isoform loss.

LanguageEnglish

CategoryHealthcare

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Pages14

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ABSTRACT

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INTRODUCTION

Original Article Common and distinct roles of AMPKγ isoforms in small-molecule activator-stimulated glucose uptake in mouse skeletal muscle Dipsikha Biswas1, Ever Espino-Gonzalez1, Danial Ahwazi1, Jordana B. Freemantle1, Amy M. Ehrlich1, Charline Jomard 2, Jonas Brorson 3, 4, Agnete N. Schou5, 6, Jean Farup3, 4, Julien Gondin2, Jesper Just5, 6, Marc Foretz 7, Jonas T. Treebak1, Marianne Agerholm1, Kei Sakamoto1, * ABSTRACT Objectives: Small-molecule activators targeting the allosteric drug and metabolite (ADaM) site of AMPK enhance insulin-independent glucose uptake in skeletal muscle and lower glucose in preclinical models of hyperglycemia. The regulatory AMPKγ subunit plays a central role in energy sensing. While the skeletal muscle-selective γ3 isoform is essential for AMP/ZMP-induced glucose uptake, it is dispensable for ADaM site-binding activators. We hypothesized that the predominant γ1 isoform is required for ADaM site activator-stimulated glucose uptake in skeletal muscle. Methods: Single-nucleus RNA sequencing (snRNA-seq) was performed on mouse and human skeletal muscle mapping AMPK subunit isoform distribution across resident cell types. To determine γ isoform-specific requirements for activator-stimulated glucose uptake, skeletal musclespecific inducible AMPKγ1/γ3 double knockout (imγ1 − / − /γ3 − / − ) and single knockout (imγ1 − / − and imγ3 − / − ) mice were generated. Ex vivo glucose uptake was measured following treatment with AICAR (AMP-mimetic) or MK-8722 (ADaM site activator), and in vivo MK-8722-induced blood glucose lowering was assessed. Results: snRNA-seq revealed distinct AMPK isoform distribution: γ1 was ubiquitously expressed, whereas γ3 was enriched in glycolytic myofibers in both mouse and human skeletal muscle. Ex vivo, glucose uptake stimulated by either AICAR or MK-8722 was severely blunted in imγ1 − / − /γ3 − / − muscle, and MK-8722-induced blood glucose lowering was significantly blunted in vivo. AICAR but not MK-8722-stimulated muscle glucose uptake was abolished in imγ3 − / − , whereas both activators fully retained effects on glucose uptake and glucose lowering in imγ1 − / − mice. Conclusions: While γ1 predominates in stabilizing the AMPKα2β2γ1 complex, it is dispensable for AMPK activator-stimulated glucose uptake in skeletal muscle, whether mediated via the nucleotide-binding or ADaM site. © 2025 The Author(s) . 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/](http://creativecommons.org/licenses/by-nc-nd/4.0/).)[).](http://creativecommons.org/licenses/by-nc-nd/4.0/).) Keywords AMP-activated protein kinase; AICAR; MK-8722; Glucose uptake; Single nucleus RNA sequencing 1. INTRODUCTION AMP-activated protein kinase (AMPK) is a central energy sensor that plays a pivotal role in maintaining cellular homeostasis through coordinating metabolic signaling pathways in response to acute energetic perturbations, such as during physical exercise and muscle contractions, hypoxia, and mitochondrial poisoning [1 ,2] . AMPK functions as a heterotrimeric complex composed of a catalytic α -subunit and regulatory β -and γ-subunits. In both humans and rodents, each subunit has multiple isoforms (α1, -α2; -β1, -β2; -γ1,-γ2, -γ3) encoded by distinct genes (PRKAA1, PRKAA2; PRKAB1, PRKAB2; PRKAG1, PRKAG2, PRKAG3), allowing for twelve possible heterotrimeric combinations with tissue- and cell type-specific expression profiles [3 ,4] . Compositional analyses of skeletal muscle from humans and mice have shown that AMPKα2β2γ1 and AMPKα2β2γ3 are the predominant complexes, accounting for approximately 85—90% of total AMPK trimers in human vastus lateralis [5] and mouse extensor digitorum longus (EDL) muscle [6], with the α2β2γ3 isoform contributing approximately 20% of this pool. AMPKγ3 is expressed almost exclusively in glycolytic skeletal muscle [7], with negligible expression detected in other tissues,

FAQs

What is the study’s main goal regarding AMPKγ isoforms?

To determine whether the predominant AMPKγ1 isoform is required for ADaM-site activator-stimulated glucose uptake in skeletal muscle, and how it differs from γ3.

How were AMPKγ isoform distributions and glucose uptake effects assessed?

Single-nucleus RNA sequencing mapped AMPK isoform distribution across resident cell types, and glucose uptake was tested ex vivo with AICAR or MK-8722. In vivo, MK-8722-induced blood glucose lowering was also measured.

What key results were found about γ1 versus γ3 roles?

γ1 was ubiquitously expressed, while γ3 was enriched in glycolytic myofibers. ADaM activator (MK-8722) and AICAR responses were differentially blunted or preserved depending on whether γ1 or γ3 was knocked out.

Sep 28, 2026

Uploaded by Bintang