Protein Phosphatase 1α and Cofilin Regulate Nuclear Translocation of NF-κB and Promote Expression of the Anti-Inflammatory Cytokine Interleukin-10 by T Cells

Abstract

While several protein serine/threonine kinases control cytokine production by T cells, the roles of serine/threonine phosphatases are largely unexplored. Here, we analyzed the involvement of protein phosphatase 1α (PP1α) in cytokine synthesis following costimulation of primary human T cells. Small interfering RNA (siRNA)-mediated knockdown of PP1α (PP1) or expression of a dominant negative PP1α (D95N-PP1) drastically diminished interleukin-10 (IL-10) production. Focusing on a key transcriptional activator of human IL-10, we demonstrate that nuclear translocation of NF-κB was significantly inhibited in PP1 or D95N-PP1 cells. Interestingly, knockdown of cofilin, a known substrate of PP1 containing a nuclear localization signal, also prevented nuclear accumulation of NF-κB. Expression of a constitutively active nonphosphorylatable S3A-cofilin in D95N-PP1 cells restored nuclear translocation of NF-κB and IL-10 expression. Subpopulation analysis revealed that defective nuclear translocation of NF-κB was most prominent in CD4 CD45RA CXCR3 T cells that included IL-10-producing T2 cells. Together these findings reveal novel functions for PP1α and its substrate cofilin in T cells namely the regulation of the nuclear translocation of NF-κB and promotion of IL-10 production. These data suggest that stimulation of PP1α could limit the overwhelming immune responses seen in chronic inflammatory diseases.

Kinome Profiling of NF1-Related MPNSTs in Response to Kinase Inhibition and Doxorubicin Reveals Therapeutic Vulnerabilities

“…We also measured an increase in PKCζ/λ (T410/T4033) and cofilin (S3) phosphorylation at the 2-day time point with both single and combined kinase inhibition ( Figure S5). Cofilin is an actin depolymerizing factor known to regulate actin dynamics and cell invasion; however, recent studies have established the role of cofilin in NFκB nuclear translocation [31,32]. The atypical protein kinase C member PKCζ is involved in several survival pathways that are deregulated in cancer and is also involved in the activation of NFκB [33,34].…”

Phosphatase inhibitor PPP1R11 modulates resistance of human T cells toward Treg-mediated suppression of cytokine expression

“…This is in agreement with our findings that PPP1R11 did not alter the NF‐κB signaling molecules studied despite affecting NF‐κB target genes. Another very recently published study confirmed that PP1A affected NF‐κB signaling in T cells and consequently cytokine expression including IL‐2, IL‐10, and to a lesser extent IFN‐γ. However, it needs to be noted that the authors used PHA‐stimulated T cell blasts that were expanded in IL‐2‐containing medium before use for functional studies and costimulation, and hence the comparability to our study may be limited, while Mock et al .…”

“…Hence, therapeutic targeting of these noncatalytic subunits may offer a unique opportunity for context‐specific modulation of PP1. Importantly, PP1A has been recently shown to be involved in T cell activation and cytokine expression via augmenting TCR‐induced NF‐κB activation without affecting classical upstream NF‐κB signaling molecules . PPP1R11 itself has been shown to be involved in apoptosis and cell cycle regulation chiefly by regulating the conformation of PP1 and affecting its interaction with PIPs rather than regulating gene expression of PP1 …”

Effect of Lycium barbarum Polysaccharide on Decreasing Serum Amyloid A3 Expression through Inhibiting NF-κB Activation in a Mouse Model of Diabetic Nephropathy

“…Upon cell activation, I κ B is phosphorylated and degraded, and the NLS is unmasked, leading to the nuclear transport of NF- κ B. The translocation in the nucleus is thought to contribute to the inflammatory gene expressions [ 47 , 48 ]. The levels of inflammatory factors such as IL2, IL6, TNF α , IFN γ , MCP-1, ICAM-1, vascular adhesion molecule 1 (VCAM-1), and toll-like receptor 4 (TLR-4) are reported to be downregulated by the inhibition of NF- κ B p65 nuclear translocation [ 23 , 49 ].…”