Activin receptor type-2A and type-2B (ACVR2A/ACVR2B)

The Activin receptor type-2A (ACVR2A) and type-2B (ACVR2B) are transmembrane serine/threonine kinase receptors that mediate signaling for a broad range of TGF-beta superfamily ligands, including activins, growth differentiation factors (GDFs), and bone morphogenetic proteins (BMPs) (UniProt P27037, Q13705). Upon ligand binding, these type II receptors form heteromeric complexes with type I receptors, triggering the phosphorylation of SMAD2/3 or SMAD1/5/8 proteins to regulate gene expression (Cusabio, 2025). This signaling axis is a fundamental regulator of erythropoiesis, skeletal muscle growth, bone remodeling, and vascular homeostasis (NIH, 2024). Dysregulation of this pathway, particularly overactive SMAD2/3 signaling, is a key driver in the pathogenesis of pulmonary arterial hypertension (PAH), ineffective erythropoiesis in myelodysplastic syndromes (MDS) and beta-thalassemia, and muscle wasting conditions (Patsnap, 2024). Therapeutic intervention typically involves 'ligand traps' such as Sotatercept and Luspatercept, which are fusion proteins that sequester circulating ligands to restore signaling balance (FDA, 2024). Other approaches include monoclonal antibodies like Bimagrumab that directly block the receptors to promote muscle mass and metabolic health (Cusabio, 2025). While effective, these therapies require careful monitoring for safety concerns such as hypertension and erythrocytosis (MDPI, 2024).

Other names

ActRIIAActRIIBActivin type II receptorsACVR2TGF-beta superfamily signaling axisActivin receptor type IIAActivin receptor type IIB

Ligand trapping and receptor blockade to inhibit SMAD2/3 signaling and modulate SMAD1/5/8 pathways to restore homeostatic signaling balance.