LPS stimulation of human PBMC-derived macrophages

Immunoresponsive gene 1 (IRG1) is one of the highest induced genes in macrophages under pro-inflammatory conditions and its function has been recently described: it codes for immune-responsive gene 1 protein/cis-aconitic acid decarboxylase (IRG1/CAD), an enzyme catalyzing the production of itaconic acid from cis-aconitic acid, a tricarboxylic acid (TCA) cycle intermediate. Itaconic acid possesses specific antimicrobial properties inhibiting isocitrate lyase, the first enzyme of the glyoxylate shunt, an anaplerotic pathway that bypasses the TCA cycle and enables bacteria to survive on limited carbon conditions. To elucidate the mechanisms underlying itaconic acid production through IRG1 induction in macrophages, we examined the transcriptional regulation of IRG1. Using a combination of literature information, transcription factor prediction models and genome-wide expression arrays, we inferred the regulatory network of IRG1 in mouse and human macrophages.

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Tallam A, Perumal TM, Antony PM, Jäger C, Fritz JV, Vallar L, Balling R, Del Sol A, Michelucci A