Modulation of Inflammatory Gene Expression by the Ribotoxin Deoxynivalenol Involves Coordinate Regulation of the Transcriptome and Translatome

Abstract

The trichothecene deoxynivalenol (DON), a common contaminant of cereal-based foods, is a ribotoxic mycotoxin known to activate innate immune cells in vivo and in vitro. Although it is recognized that DON induces transcription and mRNA stabilization of inflammation-associated mRNAs in mononuclear phagocytes, it is not known if this toxin affects translation of selected mRNA species in the cellular pool. To address this question, we employed a focused inflammation/autoimmunity PCR array to compare DON-induced changes in profiles of polysome-associated mRNA transcripts (translatome) to total cellular mRNA transcripts (transcriptome) in the RAW 264.7 murine macrophage model. Exposure to DON at 250 ng/ml (0.84 µM) for 6 h induced robust expression changes in inflammatory response genes including cytokines, cytokine receptors, chemokines, chemokine receptors, and transcription factors, with 73% of the changes being highly comparable within transcriptome and translatome populations. When expression changes of selected representative inflammatory response genes in the polysome and cellular mRNA pools were quantified in a follow-up study by real-time PCR, closely coordinated regulation of the translatome and transcriptome was confirmed; however, modest but significant differences in the relative expression of some genes within the two pools were also detectable. Taken together, DON's capacity to alter translation expression of inflammation-associated genes appears to be driven predominantly by selective transcription and mRNA stabilization that have been reported previously; however, a small subset of these genes appear to be further regulated at the translational level.