The protein Sox2 can detect bacterial DNA and trigger an immune response in mouse and human specialized white blood cells called neutrophils, according to a report published in Nature Immunology.

Sox2 has a key role during embryonic development and can convert adult cells into induced pluripotent stem (iPS) cells. In embryonic stem cells Sox2 is localized in the nucleus, where it interacts with the DNA to control the expression of genes involved in development. Zusen Fan and colleagues now show that in neutrophils, which in mammals serve as the first line of defence against invading pathogens, Sox2 is localized in the cytoplasm. Here, Sox2 directly recognizes the DNA of several pathogenic bacteria and activates the pathway that leads to an antibacterial immune response in these cells.This DNA-sensing function of Sox2 is specific to neutrophils and not found in other cells of the innate immune system. The evolutionary basis for such functional diversion remains unclear, but this unexpected function may provide potential therapeutic strategies for the treatment of infectious diseases.