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Imeglimin Attenuates Skeletal Muscle Atrophy in Mouse Models of Obesity and Aging

ABSTRACT: Abstract Background Sarcopenia is a major contributor to frailty and mortality in aging and obesity and is tightly linked to metabolic dysfunction. Imeglimin is a first-in-class oral hypoglycemic agent targeting mitochondrial function; however, despite the central role of mitochondria in skeletal muscle homeostasis, its effects on skeletal muscle under sarcopenia-relevant conditions remain unclear. Methods Imeglimin was administered to male C57BL/6 mice with high-fat diet (HFD)–induced obesity for six weeks and to naturally aged (18-month-old) male mice for 12 weeks. Skeletal muscle fiber morphology and transcriptomic profiles were analyzed in fast- and slow-twitch muscles. In parallel, C2C12 myotubes were exposed to palmitate with or without imeglimin, and inflammatory gene expression and reactive oxygen species (ROS) generation were assessed. Results Imeglimin significantly increased the cross-sectional area (CSA) of Type II fibers in the extensor digitorum longus (EDL) muscle of HFD-fed mice (+66%, P < 0.01 vs. controls). Transcriptomic analyses revealed suppression of conserved molecular signatures of muscle atrophy, including activation of immediate-early genes and inflammatory pathways (-62 to -79%, P < 0.05 vs. HFD-fed mice). In palmitate-treated C2C12 myotubes, imeglimin attenuated lipotoxicity-induced inflammatory gene expression (-28 to -72%, P < 0.05 vs. controls) with reduced ROS generation, consistent with its cell-autonomous effect on myocytes. Notably, in naturally aged mice, 12-week imeglimin treatment preserved EDL muscle fiber size (+14%, P < 0.05 vs. controls) without altering systemic glucose tolerance, accompanied by transcriptomic changes overlapping with those observed in the HFD model (-27 to -82%, P < 0.05 vs. aged controls). Conclusions Imeglimin attenuates skeletal muscle atrophy in obesity and aging, accompanied by coordinated suppression of stress- and inflammation-associated transcriptional programs. These findings indicate that pharmacological regulation of mitochondrial stress responses influences skeletal muscle vulnerability under chronic metabolic stress and identify skeletal muscle as a previously underappreciated target of imeglimin action.

ORGANISM(S): Mus musculus

PROVIDER: GSE334796 | GEO | 2026/06/18

REPOSITORIES: GEO

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Project description:Mitochondrial dysfunction caused by mitochondrial (mtDNA) deletions have been associated with skeletal muscle atrophy and myofiber loss. However, whether such defects occurring in myofibers cause sarcopenia is unclear. Also, the contribution of mtDNA alterations in muscle stem cells (MuSCs) to sarcopenia remain to be investigated. We expressed a dominant-negative variant of the mitochondrial helicase, which induces mtDNA alterations, specifically in differentiated myofibers (K320Eskm mice) and MuSCs (K320Emsc mice), respectively, and investigated their impact on muscle structure and function by immunohistochemistry, analysis of mtDNA and respiratory chain content, muscle transcriptome and functional tests. K320Eskm mice at 24 months of age had higher levels of mtDNA deletions compared to controls in soleus (SOL, 0.07673 % vs 0.00015 %, p=0.0167), extensor digitorium longi (EDL, 0.0649 vs 0.000925, p= 0.0015) and gastrocnemius (GAS, 0.09353 vs 0.000425, p=0.0004). K320Eskm mice revealed a progressive increase in the proportion of cytochrome c oxidase deficient fibers (COX-) in cross sections, reaching a maximum of 3.03%, 4.36%, 13.58% and 17.08% in EDL, SOL, tibialis anterior (TA) and GAS, respectively. However, mice did not show accelerated loss of muscle mass, muscle strength or physical performance. Histological analyses revealed ragged red fibers but also stimulated regeneration, indicating activation of MuSCs. RNAseq demonstrated enhanced expression of genes associated with protein synthesis, but also degradation, as well as muscle fiber differentiation and cell proliferation. In contrast, 7 days after destruction by cardiotoxin, regenerating TA of K320Emsc mice showed 30% of COX- fibers. Notably, regenerated muscle showed dystrophic changes, increased fibrosis (2.5% vs 1.6%, p=0.0003), increased abundance of fat cells (2.76% vs 0.23%, p=0.0144) and reduced muscle mass (regenerated TA: 40.0mg vs 60.2mg, p=0.0171). In contrast to muscles from K320Eskm mice, freshly isolated MuSCs from aged K320Emsc mice were completely devoid of mtDNA alterations. However, after passaging, mtDNA copy number as well as respiratory chain subunits and p62 levels gradually decreased.Taken together, accumulation of large-scale mtDNA alterations in myofibers alone is not sufficient to cause sarcopenia. Expression of K320E is tolerated in quiescent MuSCs, but progressively leads to mtDNA and respiratory chain depletion upon activation, in vivo and in vitro, possibly caused by an increased mitochondrial removal. Altogether, our results suggest that the accumulation of mtDNA alterations in myofibers activates regeneration during aging, which leads to sarcopenia if such alterations have expanded in MuSCs as well.

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Imeglimin Attenuates Skeletal Muscle Atrophy in Mouse Models of Obesity and Aging

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