The Drosophila type II receptor, Wishful thinking, binds BMP and myoglianin to activate multiple TGFβ family signaling pathways

Wishful thinking (Wit) is a Drosophila transforming growth factor-beta (TGF beta) superfamily type II receptor most related to the mammalian bone morphogenetic protein (BMP) type II receptor, BMPRII. To better understand its function, we undertook a biochemical approach to establish the ligand binding repertoire and downstream signaling pathway. We observed that BMP4 and BMP7, bound to receptor complexes comprised of Wit and the type I receptor thickveins and saxophone to activate a BMP-like signaling pathway. Further we demonstrated that both myoglianin and its most closely related mammalian ligand, myostatin, interacted with a Wit and Baboon (Babo) type II-type I receptor complex to activate TGF beta/activin-like signaling pathways. These results thereby demonstrate that Wit binds multiple ligands to activate both BMP and TGF beta-like signaling pathways. Given that myoglianin is expressed in muscle and glial-derived cells, these results also suggest that Wit may mediate myoglianin-dependent signals in the nervous system. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.