Interleukin 1 β-induced SMAD2/3 linker modifications are TAK1 dependent and delay TGFβ signaling in primary human mesenchymal stem cells.

Autor: van den Akker GG; Radboud University Medical Center, Department of Rheumatology, Experimental Rheumatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands., van Beuningen HM; Radboud University Medical Center, Department of Rheumatology, Experimental Rheumatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands., Vitters EL; Radboud University Medical Center, Department of Rheumatology, Experimental Rheumatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands., Koenders MI; Radboud University Medical Center, Department of Rheumatology, Experimental Rheumatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands., van de Loo FA; Radboud University Medical Center, Department of Rheumatology, Experimental Rheumatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands., van Lent PL; Radboud University Medical Center, Department of Rheumatology, Experimental Rheumatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands., Blaney Davidson EN; Radboud University Medical Center, Department of Rheumatology, Experimental Rheumatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands., van der Kraan PM; Radboud University Medical Center, Department of Rheumatology, Experimental Rheumatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands. Electronic address: p.vanderkraan@reuma.umcn.nl.
Jazyk: angličtina
Zdroj: Cellular signalling [Cell Signal] 2017 Dec; Vol. 40, pp. 190-199. Date of Electronic Publication: 2017 Sep 21.
DOI: 10.1016/j.cellsig.2017.09.010
Abstrakt: Background: Chondrogenic differentiation of mesenchymal stem cells (MSC) requires transforming growth factor beta (TGFβ) signaling. TGFβ binds to the type I receptor activin-like kinase (ALK)5 and results in C-terminal SMAD2/3 phosphorylation (pSMAD2/3C). In turn pSMAD2/3C translocates to the nucleus and regulates target gene expression. Inflammatory mediators are known to exert an inhibitory effect on MSC differentiation. In this study we investigated the effect of interleukin 1 β (IL1β) on SMAD2/3 signaling dynamics and post-translational modifications.
Results: Co-stimulation of MSC with TGFβ and IL1β did not affect peak pSMAD2C levels at 1h post-stimulation. Surprisingly, SMAD3 transcriptional activity, as determined by the CAGA 12 -luciferase reporter construct, was enhanced by co-stimulation of TGFβ and IL1β compared to TGFβ alone. Furthermore, IL1β stimulation induced CAGA 12 -luciferase activity in a SMAD dependent way. As SMAD function can be modulated independent of canonical TGFβ signaling through the SMAD linker domain, we studied SMAD2 linker phosphorylation at specific threonine and serine residues. SMAD2 linker threonine and serine modifications were observed within 1h following TGFβ, IL1β or TGFβ and IL1β stimulation. Upon co-stimulation linker modified SMAD2 accumulated in the cytoplasm and SMAD2/3 target gene transcription (ID1, JUNB) at 2-4h was inhibited. A detailed time course analysis of IL1β-induced SMAD2 linker modifications revealed a distinct temperospatial pattern compared to TGFβ. Co-stimulation with both factors resulted in a similar kinetic profile as TGFβ alone. Nevertheless, IL1β did subtly alter TGFβ-induced pSMAD2C levels between 8 and 24h post-stimulation, which was reflected by TGFβ target gene expression (PAI1, JUNB). Direct evidence for the importance of SMAD3 linker modifications for the effect of IL1β on TGFβ signaling was obtained by over-expression of SMAD3 or a SMAD3 linker phospho-mutant. Finally, an inhibitor screening was performed to identify kinases involved in SMAD2/3 linker modifications. We identified TAK1 kinase activity as crucial for IL1β-induced SMAD2 linker modifications and CAGA 12 -luciferase activity.
Conclusions: TGFβ and IL1β signaling interact at the SMAD2/3 level in human primary MSC. Down-stream TGFβ target genes were repressed by IL1β independent of C-terminal SMAD2 phosphorylation. We demonstrate that SMAD2/3 linker modifications are required for this interplay and identified TAK1 as a crucial mediator of IL1β-induced TGFβ signal modulation.
(Copyright © 2017 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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