Activation of GSK3 Prevents Termination of TNF-Induced Signaling

© 2021 Welz et al..

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 AND METHODS: 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/β-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 GSK3β and PKCβ expression and GSK3α/β-Ser21/9 and PKCα/βII-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/β-knockdown modestly increased, whereas GSK3α/β-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/β-Ser176/180 phosphorylation were not affected. Moreover, PKCβ-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.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:14

Enthalten in:

Journal of inflammation research - 14(2021) vom: 13., Seite 1717-1730

Sprache:

Englisch

Beteiligte Personen:

Welz, Bastian [VerfasserIn]
Bikker, Rolf [VerfasserIn]
Hoffmeister, Leonie [VerfasserIn]
Diekmann, Mareike [VerfasserIn]
Christmann, Martin [VerfasserIn]
Brand, Korbinian [VerfasserIn]
Huber, René [VerfasserIn]

Links:

Volltext

Themen:

GSK3
IL-8
Journal Article
NF-κB
PKC
Staurosporine
TNF
Termination of TNF-induced signaling
Termination of inflammation

Anmerkungen:

Date Revised 23.04.2022

published: Electronic-eCollection

Citation Status PubMed-not-MEDLINE

doi:

10.2147/JIR.S300806

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM325379769