PMID: 22921829

Authors:

Aragon E, Goerner N, Xi Q, Gomes T, Gao S, Massague J, Macias MJ

Title:

Structural Basis for the Versatile Interactions of Smad7 with Regulator WW Domains in TGF-beta Pathways.

Journal:

Structure. 2012 Oct 10;20(10):1726-36. doi: 10.1016/j.str.2012.07.014. Epub 2012 , Aug 23.

Abstract:

Transforming growth factor (TGF)-beta and BMP signaling is mediated by Smads 1-5 (R-Smads and Co-Smads) and inhibited by Smad7, a major hub of regulation of TGF-beta and BMP receptors by negative feedback and antagonistic signals. The transcription coactivator YAP and the E3 ubiquitin ligases Smurf1/2 and Nedd4L target R-Smads for activation or degradation, respectively. Pairs of WW domain in these regulators bind PY motifs and adjacent CDK/MAPK and GSK3 phosphorylation sites in R-Smads in a selective and regulated manner. In contrast, here we show that Smad7 binds YAP, Smurf1, Smurf2, and Nedd4L constitutively, the binding involving a PY motif in Smad7 and no phosphorylation. We also provide a structural basis for how regulators that use WW domain pairs for selective interactions with R-Smads, resort to one single versatile WW domain for binding Smad7 to centralize regulation in the TGF-beta and BMP pathways.