Metformin induces muscle atrophy by transcriptional regulation of myostatin via HDAC6 and FoxO3a

Abstract

Background Skeletal muscle atrophy is a severe condition that involves loss of muscle mass and quality. Drug intake can also cause muscle atrophy. Biguanide metformin is the first-line and most widely prescribed anti-diabetic drug for patients with type 2 diabetes. The molecular mechanism of metformin in muscle is unclear. Methods Myostatin expression was investigated at the protein and transcript levels after metformin administration. To investigate the pathways associated with myostatin signalling, we used real-time polymerase chain reaction, immunoblotting, luciferase assay, chromatin immunoprecipitation assay, co-immunoprecipitation, immunofluorescence, primary culture, and confocal microscopy. Serum analysis, physical performance, and immunohistochemistry were performed using our in vivo model. Results Metformin induced the expression of myostatin, a key molecule that regulates muscle volume and triggers the phosphorylation of AMPK. AMPK alpha2 knockdown in the background of metformin treatment reduced the myostatin expression of C2C12 myotubes (À49.86 ± 12.03%, P < 0.01) and resulted in increased myotube diameter compared with metformin (+46.62 ± 0.88%, P < 0.001). Metformin induced the interaction between AMPK and FoxO3a, a key transcription factor of myostatin. Metformin also altered the histone deacetylase activity in muscle cells (>3.12fold ± 0.13, P < 0.001). The interaction between HDAC6 and FoxO3a induced after metformin treatment. Confocal microscopy revealed that metformin increased the nuclear localization of FoxO3a (>3.3-fold, P < 0.001). Chromatin immunoprecipitation revealed that metformin induced the binding of FoxO3a to the myostatin promoter. The transcript-level expression of myostatin was higher in the gastrocnemius (GC) muscles of metformin-treated wildtype (WT) (+68.9 ± 10.01%, P < 0.001) and db/db mice (+55.84 ± 6.62%, P < 0.001) than that in the GC of controls (n = 4 per group). Average fibre cross-sectional area data also showed that the metformin-treated C57BL/6J (WT) (À31.74 ± 0.75%, P < 0.001) and C57BLKS/J-db/db (À18.11 ± 0.94%, P < 0.001) mice had decreased fibre size of GC compared to the controls. The serum myoglobin level was significantly decreased in metformin-treated WT mice (À66.6 ± 9.03%, P < 0.01). Conclusions Our results demonstrate that metformin treatment impairs muscle function through the regulation of myostatin in skeletal muscle cells via AMPK-FoxO3a-HDAC6 axis. The muscle-wasting effect of metformin is more evident in WT than in db/db mice, indicating that more complicated mechanisms may be involved in metformin-mediated muscular dysfunction.

A Study of the Ameliorative Effect of Gryllus bimaculatus on Sarcopenia

“…마이오스타틴은 골격근에서 발현되어 근육 성장 음성 조절자 역할을 하는 MuRF1 및 atrogin-1의 발현을 유도함으로써 근육 단백질(류신, 이소류신, 발린) 합성을 억제하여 근육 성장을 억 제한다 (Lee & McPherron, 2001). 이러한 마이오스타틴 억제를 통해 근성장을 유도하는 것이 근감소증 치료의 주된 표적으로 알려져 있 다 (Kang et al, 2021). 근육단백질의 구성성분인 분지아미노산인 류 신, 이소류신, 발린은 그릴루스 비마클루투스에 많이 함유되어 있어 (Kim et al, 2020)…”

Potential Benefits of Combined Statin and Metformin Therapy on Resistance Training Response in Older Individuals

“…Reduced mitochondrial content and function, disruptions in glucose and calcium metabolism, and inhibition of mTORC1 signaling resulting in protein breakdown via FOXO and atrogin-1 pathways are proposed mechanisms for statin intolerance ( Bonifacio et al, 2015 ; Du Souich et al, 2017 ; Elsaid et al, 2017 ). A new report also shows metformin affects the FOXO-myostatin signaling axis causing muscle atrophy ( Kang et al, 2021 ). With many overlapping and parallel mechanisms of action, the possible benefit of combination therapy has been proposed ( van Stee et al, 2018 ).…”

Identification of Agents That Ameliorate Hyperphosphatemia-Suppressed Myogenin Expression Involved in the Nrf2/p62 Pathway in C2C12 Skeletal Muscle Cells

“…In our drug-screening results, we identified many potential drugs, including metformin and phenformin. The effects of metformin on muscle are still uncertain and, therefore, a matter of debate [ 29 , 30 ], because metformin use does not alter mTOR expression, thus appearing to negate this theory [ 31 ]. The use of metformin in preventing the development of sarcopenia in older people with prediabetes is supported by the results of a clinical trial [ 32 ].…”