Fig 2: Ribosomal/TRP53 pathway pattern mediated by Salmonella infection. Following the intracellular invasion of Salmonella, the bacterium secretes proteins that inhibit the transcription of RPL39 and RPL9, and then increases the accumulation of TRP53. TRP53 acts on the FAS/CASP6 sub-pathway and promotes apoptosis. TRP53 can also modulate the GADD45A sub-network and causes cell cycle arrest. Besides RPL39 and RPL9, three genes (ABL1, F2, and PTEN) which promote TRP53 activity, and four genes (AKT1, SDCBP, PSEN1, and TNFRSF8) which inhibit TRP53 activity were differentially expressed in neutrophils infected with Salmonella. The regulatoryrelationships shown in this figure were either discovered in this study or curated from gene expression regulation relationships deposited in GEREDB database [18].

Fig 3: Modulation of the ribosomal/TRP53 pathway increases evidence of apoptosis and immune system arrest. The transcription level of four apoptosis genes and two innate immunity genes were measured via RT-PCR following pre-treatment with TRL39 siRNA, RPL9 siRNA, TRP53 inhibitor, or TRP53 activator and infection with Salmonella. Gene expression was normalized to GAPDH transcription level \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${2}^{\Delta 40-\mathrm{ct}}$$\end{document}2Δ40-ct for A FAS, B RB1, C CASP6, D GADD45A, E NFKB, and F INFG. Error bars represent mean ± SD. * = P < 0.05 (ANOVA test, number of replicates = 3).

Fig 4: Reducing RPL39 and RPL9 expression through siRNA knock-down up-regulates TRP53 expression in neutrophils. Flow cytometry plots for rested and stimulated neutrophils following antibody staining for TRP53 (FITC-A) and CD14 (PE-A). Neutrophils were either untreated at zero hours (column T0), treated for four hours (column T4), or treated for eight hours (column T8) with RPL39 siRNA (row A), RPL9 siRNA (row B), TRP53 inhibitor (row C), or TRP53 activator (row D).