Sakamoto Kotaro, Kanematsu-Yamaki Yoko, Kamada Yusuke, Oka Masahiro, Ohnishi Toshiyuki, Miwa Masanori, Asami Taiji, Inooka Hiroshi
Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan.
Biochem Biophys Rep. 2017 Jun 10;11:33-39. doi: 10.1016/j.bbrep.2017.06.001. eCollection 2017 Sep.
ActRIIB (activin receptor type-2B) is an activin receptor subtype constitutively expressed in the whole body, playing a role in cellular proliferation, differentiation, and metabolism. For its various physiological activities, ActRIIB interacts with activin and multiple other ligands including myostatin (MSTN), growth differentiation factor 11 (GDF11), and bone morphogenetic protein 9 (BMP9). Notably, the protein-protein interaction (PPI) between ActRIIB and MSTN negatively controls muscular development. Therefore, this PPI has been targeted for effective treatment of muscle degenerative diseases such as muscular dystrophy and sarcopenia. Here, we report the identification of ligand-selective peptidic ActRIIB-antagonists by phage display technology. Our peptides bound to the extracellular domain of ActRIIB, inhibited PPIs between ActRIIB expressed on the cell surface and its ligands, and subsequently suppressed activation of Smad that serves as the downstream signal of the ActRIIB pathway. Interestingly, these peptidic antagonists displayed different ligand selectivities; the AR2mini peptide inhibited multiple ligands (activin A, MSTN, GDF11, and BMP9), AR9 inhibited MSTN and GDF11, while AR8 selectively inhibited MSTN. This is the first report of artificial peptidic ActRIIB-antagonists possessing ligand-selectivity.
激活素受体IIB（ActRIIB）是一种在全身组成性表达的激活素受体亚型，在细胞增殖、分化和代谢中发挥作用。由于其多种生理活性，ActRIIB与激活素以及多种其他配体相互作用，包括肌肉生长抑制素（MSTN）、生长分化因子11（GDF11）和骨形态发生蛋白9（BMP9）。值得注意的是，ActRIIB与MSTN之间的蛋白质-蛋白质相互作用（PPI）对肌肉发育起负调控作用。因此，这种PPI已成为有效治疗肌肉萎缩症和肌肉减少症等肌肉退行性疾病的靶点。在此，我们报告通过噬菌体展示技术鉴定出配体选择性肽类ActRIIB拮抗剂。我们的肽与ActRIIB的胞外域结合，抑制细胞表面表达的ActRIIB与其配体之间的PPI，并随后抑制作为ActRIIB途径下游信号的Smad的激活。有趣的是，这些肽类拮抗剂表现出不同的配体选择性；AR2mini肽抑制多种配体（激活素A、MSTN、GDF11和BMP9），AR9抑制MSTN和GDF11，而AR8选择性抑制MSTN。这是关于具有配体选择性的人工肽类ActRIIB拮抗剂的首次报道。
