TMEPAI, a transmembrane TGF-beta-inducible protein, sequesters Smad proteins from active participation in TGF-beta signaling.
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Watanabe Y, Itoh S, Goto T, Ohnishi E, Inamitsu M, Itoh F, Satoh K, Wiercinska E, Yang W, Shi L, Tanaka A, Nakano N, Mommaas AM, Shibuya H, Ten Dijke P, Kato M
TMEPAI, a transmembrane TGF-beta-inducible protein, sequesters Smad proteins from active participation in TGF-beta signaling.
Mol Cell. 2010 Jan 15;37(1):123-34. doi: 10.1016/j.molcel.2009.10.028.
- PubMed ID
- 20129061 [ View in PubMed]
- Abstract
Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine of key importance for controlling embryogenesis and tissue homeostasis. How TGF-beta signals are attenuated and terminated is not well understood. Here, we show that TMEPAI, a direct target gene of TGF-beta signaling, antagonizes TGF-beta signaling by interfering with TGF-beta type I receptor (TbetaRI)-induced R-Smad phosphorylation. TMEPAI can directly interact with R-Smads via a Smad interaction motif. TMEPAI competes with Smad anchor for receptor activation for R-Smad binding, thereby sequestering R-Smads from TbetaRI kinase activation. In mammalian cells, ectopic expression of TMEPAI inhibited TGF-beta-dependent regulation of plasminogen activator inhibitor-1, JunB, cyclin-dependent kinase inhibitors, and c-myc expression, whereas specific knockdown of TMEPAI expression prolonged duration of TGF-beta-induced Smad2 and Smad3 phosphorylation and concomitantly potentiated cellular responsiveness to TGF-beta. Consistently, TMEPAI inhibits activin-mediated mesoderm formation in Xenopus embryos. Therefore, TMEPAI participates in a negative feedback loop to control the duration and intensity of TGF-beta/Smad signaling.