Figure 1. A schematic representation of ROS- and TLR-mediated gene expression.

Despite the diversity of microbes that are potential pathogens, there is precise molecular recognition of microbial products by molecules of the innate immune system, with the TLR family being 1 of the most intensely studied mediators of this recognition. There are 10 human TLRs that signal via 4 adaptor proteins and 2 initial kinases; this signaling is followed by the activation of distal kinases that subsequently regulate transcription factors such as NF-κB and activator protein 1 (AP-1), which control gene expression. Although the signaling cascade is quite narrow at its center, posttranslational modifications of kinase activity by ROS likely contribute to the diversity and intensity of gene expression after microbial activation of the innate immune system.