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Inhibition of the Transforming Growth Factor β (TGFβ) Pathway by Interleukin-1β Is Mediated through TGFβ-activated Kinase 1 Phosphorylation of SMAD3

By Germaine F.J.D. Benus, Albertus T.J. Wierenga, David J.J. de Gorter, Jan Jacob Schuringa, Ariëtte M. van Bennekum, Loes Drenth-Diephuis, Edo Vellenga and Bart J.L. Eggen

Abstract

Transforming growth factor β is the prototype of a large family of secreted factors that regulate multiple biological processes. In the immune system, TGFβ acts as an anti-inflammatory and immunosuppressive molecule, whereas the cytokine interleukin (IL)-1β is a crucial mediator of inflammatory responses and induces proinflammatory genes and acute phase proteins. Here, we present evidence for the existence of a direct inhibitory interaction between the IL-1β and TGFβ signaling cascades that is not dependent on IL-1β–induced SMAD7 expression. IL-1β and its downstream mediator TAK1 inhibit SMAD3-mediated TGFβ target gene activation, whereas SMAD3 nuclear translocation and DNA binding in response to TGFβ are not affected. IL-1β transiently induces association between TAK1 and the MAD homology 2 domain of SMAD3, resulting in SMAD3 phosphorylation. Furthermore, IL-1β alleviates the inhibitory effect of TGFβ on in vitro hematopoietic myeloid colony formation. In conclusion, our data provide evidence for the existence of a direct inhibitory effect of the IL-1β-TAK1 pathway on SMAD3-mediated TGFβ signaling, resulting in reduced TGFβ target gene activation and restored proliferation of hematopoietic progenitors

Topics: Articles
Publisher: The American Society for Cell Biology
Year: 2005
DOI identifier: 10.1091/mbc.E04-11-1033
OAI identifier: oai:pubmedcentral.nih.gov:1182292
Provided by: PubMed Central
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