LPS stimulation of human PBMC-derived macrophages. Homo sapiens

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. Overall design: 3 unstimulated (Control) and 3 LPS-stimulated human PBMC-derived macrophages

免疫反应性基因1（Immunoresponsive gene 1, IRG1）是促炎条件下巨噬细胞中诱导表达水平最高的基因之一，其功能近期已被阐明：它编码免疫反应性基因1蛋白/顺乌头酸脱羧酶（IRG1/CAD），该酶可催化顺乌头酸——一种三羧酸（TCA）循环中间产物——生成衣康酸。衣康酸具有特异性抗菌活性，能够抑制异柠檬酸裂解酶，而异柠檬酸裂解酶是乙醛酸分流的首个酶；乙醛酸分流是一条绕过TCA循环的回补途径，可帮助细菌在有限碳源条件下存活。为阐明巨噬细胞中通过IRG1诱导产生衣康酸的潜在机制，我们对IRG1的转录调控展开了研究。我们结合文献信息、转录因子预测模型与全基因组表达芯片，推断了小鼠及人源巨噬细胞中IRG1的调控网络。实验设计概述：3株未刺激（对照）的人外周血单个核细胞（peripheral blood mononuclear cell, PBMC）来源巨噬细胞，以及3株经脂多糖（lipopolysaccharide, LPS）刺激的该类巨噬细胞。