Knock in p38g and knock out p38d effect on gene expression in TLR4 signalling in bone marrow derived macrophages using LPS.

Evidence implicating p38γ and p38δ (p38γ/p38δ) in inflammation are mainly based on experiments using p38γ/p38δ deficient (p38γ/δ-/-) 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 p38γD171A/D171A/p38δ-/- (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. WT and p38γ/δKIKO bone marrow derived macrophages were stimulated with 100 ng/ml LPS for 0, 30 and 60 min, and gene expression was analysed by RNA-sequencing (RNA-Seq) to identify target genes specifically affected by the lack of p38γ kinase activity and p38δ expression.