ACVR2B

ACVR2B (activin A receptor type 2B, ActRIIB) is a type II serine/threonine kinase receptor of the transforming growth factor-β (TGF-β) superfamily and serves as a central signaling receptor for myostatin and activin ligands involved in the regulation of skeletal muscle mass and tissue remodeling^[1][2]. Mechanistically, myostatin and activin A bind ACVR2B and associated receptor complexes, leading to activation of downstream SMAD2/3 signaling and transcriptional programs that suppress muscle growth and myogenic progression^[3][4]. Through this pathway, ACVR2B functions as a key negative regulator of skeletal muscle development, while broader activin signaling contributes to multiple physiological and pathological processes, including metabolic regulation, musculoskeletal disorders, and tissue injury responses^[5][6]. In disease and experimental models, inhibition of ACVR2B signaling consistently increases skeletal muscle mass, improves body composition, and enhances insulin sensitivity, supporting its relevance in obesity, cachexia, muscular disorders, and metabolic disease research^[7][8][9]. Compared with the closely related receptor ACVR2A, ACVR2B is recognized as a high-affinity receptor for myostatin and is extensively studied as a major regulatory node controlling muscle growth through the myostatin/activin signaling axis^[3][10]. For experimental applications, soluble ACVR2B decoy receptors, ACVR2B-Fc fusion proteins, and dual ActRIIA/IIB-blocking antibodies such as bimagrumab are widely used to suppress ligand-mediated signaling, induce muscle hypertrophy, preserve lean mass, and investigate anabolic mechanisms in preclinical and clinical studies^{[7][9][11][12]}.