Snon facilitates alk1-smad1/5 signaling duringembryonic angiogenesis
n endothelial cells, two type I receptors of the transforming growth factor ? (TGF-β) family, ALK1 and ALK5, coordinate to regulate embryonic angiogenesis in response to BMP9/10 and TGF-β. Whereas TGF-β binds to and activates ALK5, leading to Smad2/3 phosphorylation and inhibition of endothelial cell proliferation and migration, BMP9/10 and TGF-β also bind to ALK1, resulting in the activation of Smad1/5. SnoN is a negative regulator of ALK5 signaling through the binding and repression of Smad2/3. Here we uncover a positive role of SnoN in enhancing Smad1/5 activation in endothelial cells to promote angiogenesis. Upon ligand binding, SnoN directly bound to ALK1 on the plasma membrane and facilitated the interaction between ALK1 and Smad1/5, enhancing Smad1/5 phosphorylation. Disruption of this SnoN-Smad interaction impaired Smad1/5 activation and up-regulated Smad2/3 activity. This resulted in defective angiogenesis and arteriovenous malformations, leading to embryonic lethality at E12.5. Thus, SnoN is essential for TGF-β/BMP9-dependent biological processes by its ability to both positively and negatively modulate the activities of Smad-dependent pathways.©2013 Zhu et al.
Journal of Cell Biology
Digital Object Identifier (DOI)
Zhu, Qingwei; Kim, Yong Hwan; Wang, Douglas; Oh, S. Paul; and Luo, Kunxin, "Snon facilitates alk1-smad1/5 signaling duringembryonic angiogenesis" (2013). Neurobiology. 673.