Activation of nuclear factor kappaB In vivo selectively protects the murine small intestine against ionizing radiation-induced damage.

Exposure of mice to total body irradiation induces nuclear factor kappaB (NFkappaB) activation in a tissue-specific manner. In addition to the spleen, lymph nodes, and bone marrow, the tissues that exhibit NFkappaB activation now include the newly identified site of the intestinal epithelial cells. NFkappaB activated by total body irradiation mainly consists of NFkappaB p50/RelA heterodimers, and genetically targeted disruption of the NFkappaB p50 gene in mice significantly decreased the activation.