p38γ and p38δ modulate innate immune response by regulating MEF2D activation
- Centro Nacional de Biotecnología/CSIC, Spain
- The Francis Crick Institute, United Kingdom
- Université de Montréal, Canada
- McGill University, Canada
- Queen's University Belfast, United Kingdom
- University College London, United Kingdom
Abstract
Evidence implicating p38γ and p38δ (p38γ/p38δ) in inflammation are mainly based on experiments using Mapk12/Mapk13 deficient (p38γ/δKO) mice, which show low levels of TPL2, the kinase upstream of MKK1-ERK1/2 in myeloid cells. This could obscure p38γ/p38δ roles, since TPL2 is essential for regulating inflammation. Here we generated a Mapk12D171A/D171A/Mapk13-/- (p38γ/δKIKO) mouse, expressing kinase-inactive p38γ and lacking p38δ. This mouse exhibited normal TPL2 levels, making it an excellent tool to elucidate specific p38γ/p38δ functions. p38γ/δKIKO mice showed a reduced inflammatory response and less susceptibility to LPS-induced septic shock and Candida albicans infection than wild-type mice. Gene expression analyses in LPS-activated WT and p38γ/δKIKO macrophages revealed that p38γ/p38δ regulated numerous genes implicated in innate immune response. Additionally, phospho-proteomic analyses and in vitro kinase assays showed that the transcription factor myocyte enhancer factor-2D (MEF2D) was phosphorylated at Ser444 via p38γ/p38δ. Mutation of MEF2D Ser444 to the non-phosphorylatable residue Ala increased its transcriptional activity and the expression of Nos2 and Il1b mRNA. These results suggest that p38γ/p38δ govern innate immune responses by regulating MEF2D phosphorylation and transcriptional activity.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting file
Article and author information
Author details
Diego González-Romero
Seyed Mehdi Jafarnejad
Juan José Sanz-Ezquerro
Funding
Ministerio de Ciencia e Innovación (PID2019-108349RB-100)
- Juan José Sanz-Ezquerro
- Ana Cuenda
Ministerio de Ciencia e Innovación (SAF2016-79792R)
- Juan José Sanz-Ezquerro
- Ana Cuenda
Wellcome Trust (FC001103)
- Steven C Ley
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All mice were housed in specific pathogen‐free conditions in the CNB‐CSIC animal house. Animal procedures were performed in accordance with national and EU guidelines, with the approval of the Centro Nacional de Biotecnología Animal Ethics Committee, CSIC and Comunidad de Madrid (Reference: PROEX 316/15 and PROEX 071/19).
Copyright
© 2023, Escós et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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p38γ and p38δ modulate innate immune response by regulating MEF2D activation
eLife 12:e86200.
https://doi.org/10.7554/eLife.86200
Further reading
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Teichoic acids (TA) are linear phospho-saccharidic polymers and important constituents of the cell envelope of Gram-positive bacteria, either bound to the peptidoglycan as wall teichoic acids (WTA) or to the membrane as lipoteichoic acids (LTA). The composition of TA varies greatly but the presence of both WTA and LTA is highly conserved, hinting at an underlying fundamental function that is distinct from their specific roles in diverse organisms. We report the observation of a periplasmic space in Streptococcus pneumoniae by cryo-electron microscopy of vitreous sections. The thickness and appearance of this region change upon deletion of genes involved in the attachment of TA, supporting their role in the maintenance of a periplasmic space in Gram-positive bacteria as a possible universal function. Consequences of these mutations were further examined by super-resolved microscopy, following metabolic labeling and fluorophore coupling by click chemistry. This novel labeling method also enabled in-gel analysis of cell fractions. With this approach, we were able to titrate the actual amount of TA per cell and to determine the ratio of WTA to LTA. In addition, we followed the change of TA length during growth phases, and discovered that a mutant devoid of LTA accumulates the membrane-bound polymerized TA precursor.
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