Pathophysiological levels of GDF11 activate Smad2/Smad3 signaling and induce muscle atrophy in human iPSC-derived myocytes

• Published in: American Journal of Physiology: Cell Physiology 2022-11, Vol.323 (5), p.C1402-C1409
• Main Authors: Honda, Mikako, Makino, Takumi, Zhao, Xiaolin, Matsuto, Mariko, Sakurai, Hidetoshi, Takahashi, Yu, Shimizu, Makoto, Sato, Ryuichiro, Yamauchi, Yoshio
• Format: Article
• Language: English
• Subjects: Atrophy; Bone Morphogenetic Proteins - metabolism; FOXO1 protein; Growth Differentiation Factors - genetics; Growth Differentiation Factors - metabolism; Growth Differentiation Factors - pharmacology; Humans; Induced Pluripotent Stem Cells - metabolism; Muscle Cells - metabolism; Muscle, Skeletal - metabolism; Muscular Atrophy - pathology; Musculoskeletal system; Myocytes; Myostatin; Myostatin - genetics; Myostatin - metabolism; Phenotypes; Skeletal muscle; Smad2 protein; Smad2 Protein - genetics; Smad3 protein; Smad3 Protein - metabolism; Transforming Growth Factor beta - metabolism; Ubiquitin; Ubiquitin-protein ligase; Ubiquitin-Protein Ligases - metabolism
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00341.2022

Skeletal muscle mass is negatively regulated by several TGF-β superfamily members. Myostatin (MSTN) is the most prominent negative regulator of muscle mass. Recent studies show that in addition to MSTN, GDF11, which shares a high sequence identity with MSTN, induces muscle atrophy in vitro and in vivo at supraphysiological levels, whereas controversy regarding its roles exists. Furthermore, higher circulating GDF11 levels associate with frailty in humans. On the other hand, little is known about the effect of pathophysiological levels of GDF11 on muscle atrophy. Here we seek to determine whether pathophysiological levels of GDF11 are sufficient to activate Smad2/Smad3 signaling and induce muscle atrophy using human iPSC-derived myocytes (hiPSC myocytes). We first show that incubating hiPSC myocytes with pathophysiological concentrations of GDF11 significantly reduces myocyte diameters. We next demonstrate that pathophysiological levels of GDF11 are sufficient to activate Smad2/3 signaling. Finally, we show that pathophysiological levels of GDF11 are capable of inducing the expression of Atrogin-1, an atrophy-promoting E3 ubiquitin ligase and that FOXO1 blockage reverses the GDF11-induced Atrogin-1 expression and atrophic phenotype. Collectively, our results suggest that GDF11 induces skeletal muscle atrophy at the pathophysiological levels through the GDF11-FOXO1 axis.