Activation of GSK3 Prevents Termination of TNF-Induced Signaling.
J Inflamm Res
; 14: 1717-1730, 2021.
Article
em En
| MEDLINE
| ID: mdl-33986607
ABSTRACT
BACKGROUND:
Termination of TNF-induced signaling plays a key role in the resolution of inflammation with dysregulations leading to severe pathophysiological conditions (sepsis, chronic inflammatory disease, cancer). Since a recent phospho-proteome analysis in human monocytes suggested GSK3 as a relevant kinase during signal termination, we aimed at further elucidating its role in this context. MATERIALS ANDMETHODS:
For the analyses, THP-1 monocytic cells and primary human monocytes were used. Staurosporine (Stauro) was applied to activate GSK3 by inhibiting kinases that mediate inhibitory GSK3α/ß-Ser21/9 phosphorylation (eg, PKC). For GSK3 inhibition, Kenpaulone (Ken) was used. GSK3- and PKC-siRNAs were applied for knockdown experiments. Protein expression and phosphorylation were assessed by Western blot or ELISA and mRNA expression by qPCR. NF-κB activation was addressed using reporter gene assays.RESULTS:
Constitutive GSK3ß and PKCß expression and GSK3α/ß-Ser21/9 and PKCα/ßII-Thr638/641 phosphorylation were not altered during TNF long-term incubation. Stauro-induced GSK3 activation (demonstrated by Bcl3 reduction) prevented termination of TNF-induced signaling as reflected by strongly elevated IL-8 expression (used as an indicator) following TNF long-term incubation. A similar increase was observed in TNF short-term-exposed cells, and this effect was inhibited by Ken. PKCα/ß-knockdown modestly increased, whereas GSK3α/ß-knockdown inhibited TNF-induced IL-8 expression. TNF-dependent activation of two NF-κB-dependent indicator plasmids was enhanced by Stauro, demonstrating transcriptional effects. A TNF-induced increase in p65-Ser536 phosphorylation was further enhanced by Stauro, whereas IκBα proteolysis and IKKα/ß-Ser176/180 phosphorylation were not affected. Moreover, PKCß-knockdown reduced levels of Bcl3. A20 and IκBα mRNA, both coding for signaling inhibitors, were dramatically less affected under our conditions when compared to IL-8, suggesting differential transcriptional effects.CONCLUSION:
Our results suggest that GSK3 activation is involved in preventing the termination of TNF-induced signaling. Our data demonstrate that activation of GSK3 - either pathophysiologically or pharmacologically induced - may destroy the finely balanced condition necessary for the termination of inflammation-associated signaling.
Texto completo:
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Inflamm Res
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Alemanha