ALK7

ALK7 (ACVR1C) is a human type I receptor serine/threonine kinase in the TGF-β receptor system^[1]. Mechanistically, activin isoforms signal through ALK7, and activin C activates SMAD2/3 signaling through ALK7 in differentiated adipocytes^[2][3]. In pancreatic islets, activin B receptor ALK7 negatively regulates β-cell function, and ALK7 activation induces pancreatic β-cell apoptosis through Akt suppression and the SMAD2-caspase-3 cascade^[4][5]. In adipose models, GDF3-ALK7 signaling regulates adipose-tissue homeostasis under nutrient overload, while ALK7 dysfunction increases lipolysis and reduces fat accumulation^[6][7]. In cancer models, ALK7 signaling functions as a suppressive tissue barrier to tumorigenesis and metastasis, and activin B-ALK7 activation induces apoptosis in neoplastic cells^[8]. Compared with related isoforms, placental ALK7 transcripts include full-length, truncated, and soluble variants generated by alternative splicing, which distinguishes receptor-bound signaling from potential soluble or truncated forms^[9]. For experimental applications, SB-431542 inhibits the highly related ALK4, ALK5, and ALK7 kinases, so it supports pathway blockade but does not isolate ALK7-specific biology^[10].- ALK7 links activin-family signaling to SMAD2/3, β-cell regulation, adipose lipid metabolism, and apoptosis.- SB-431542 blocks ALK4/5/7 together, requiring isoform-aware controls in ALK7-focused experiments.