Glycogen Synthase Kinase 3α Is the Main Isoform That Regulates the Transcription Factors Nuclear Factor-Kappa B and cAMP Response Element Binding in Bovine Endothelial Cells Infected with Staphylococcus aureus

Abstract

Glycogen synthase kinase 3 (GSK3) is a constitutive enzyme implicated in the regulation of cytokine expression and the inflammatory response during bacterial infections. Mammals have two GSK3 isoforms named GSK3α and GSK3β that plays different but often overlapping functions. Although the role of GSK3β in cytokine regulation during the inflammatory response caused by bacteria is well described, GSK3α has not been found to participate in this process. Therefore, we tested if GSK3α may act as a regulatory isoform in the cytokine expression by bovine endothelial cells infected with Staphylococcus aureus because this bacterium is one of the major pathogens that cause tissue damage associated with inflammatory dysfunction. Interestingly, although both isoforms were phosphorylated–inactivated, we consistently observed a higher phosphorylation of GSK3α at Ser21 than that of GSK3β at Ser9 after bacterial challenge. During a temporal course of infection, we characterized a molecular switch from pro-inflammatory cytokine expression (IL-8), promoted by nuclear factor-kappa B (NF-κB), at an early stage (2 h) to an anti-inflammatory cytokine expression (IL-10), promoted by cAMP response element binding (CREB), at a later stage (6 h). We observed an indirect effect of GSK3α activity on NF-κB activation that resulted in a low phosphorylation of CREB at Ser133, a decreased interaction between CREB and the co-activator CREB-binding protein (CBP), and a lower expression level of IL-10. Gene silencing of GSK3α and GSK3β with siRNA indicated that GSK3α knockout promoted the interaction between CREB and CBP that, in turn, increased the expression of IL-10, reduced the interaction of NF-κB with CBP, and reduced the expression of IL-8. These results indicate that GSK3α functions as the primary isoform that regulates the expression of IL-10 in endothelial cells infected with S. aureus.

Glycogen synthase kinase-3 beta inhibitors protectagainst the acute lung injuries resulting from acute necrotizing pancreatitis

“…NF-κB needs to be transferred from the cytoplasm to the nucleus to activate the NF-κB pathway, which binds to the promoter regions of various pro-inflammatory genes and activates transcription 18 . Cumulative evidence shows that NF-κB p65, especially the COOH-terminus of p65 at Ser 536, can be phosphorylated by GSK-3β, to strengthen transcriptional responses of NF-κB 19 . The peculiarity of GSK-3β rests with its capability of affecting the activity of the transcription factor NF-κB 20 .…”

Staphylococcus aureus internalisation enhances bacterial survival through modulation of host immune responses and mast cell activation

“…GSK-3β inhibition has been shown to suppress generation of pro-inflammatory cytokines whilst augmenting production of anti-inflammatory IL-10 in response to multiple TLR signalling pathways, through NF-κB and CREB interacting with the coactivator CREB-binding protein (CBP) 10. Downregulation of GSK-3β phosphorylation has also been shown to reduce the pro-inflammatory response, and thereby favour survival of S aureus 11. Downregulation of GSK-3β in response to IgE sensitization and S aureus infection of LAD2 cells may constitute a possible route by which S aureus downregulates cytokine production within mast cells which have previously been sensitized with anti-S aureus IgE.…”

Spatially-targeted proteomics of the host-pathogen interface during staphylococcal abscess formation

“…The presence of Gsk3a exclusively in the cortex at 10 dpi suggests a decreased metabolic demand for glucose and possible glycogen formation. In addition, Gsk3a plays a central role in regulating the transition between pro-inflammatory and immune-suppressive response to S. aureus by controlling cytokine production 111 . These results suggest a specific role for Gsk3a in altering the metabolic and cytokine landscape of the cortex 10 dpi during S. aureus infection of the kidney.…”