Generation and characterization of a novel transgenic mouse harboring conditional nuclear factor-kappa B/RelA knockout alleles

Background: Nuclear Factor-Kappa B (NF-kB) is a family of transcription factors that are important in embryonic development, inflammation, epithelial-to-mesenchymal transition and cancer. The 65 kDa RelA subunit is the major transcriptional activator of the NF-kB pathways. Whole-body deficiency of RelA leads to massive apoptosis of liver hepatocytes and death in utero. To study the role of RelA in physiology and in disease states in a manner that circumvents this embryonic lethal phenotype, we have generated a mouse with RelA conditional knockout (CKO) alleles containing loxP sites that are deleted by activated Cre recombinase. Results: We demonstrate that RelA(CKO/CKO) mice are fertile, do not display any developmental defects and can be crossed with Cre-expressing mice to delete RelA in a temporal, tissue-specific manner. Our mating of RelA(CKO/CKO) mice with Zp3-Cre transgenic led to embryonic lethality of RelA-deficient embryos. In contrast, mating of RelA(CKO/CKO) mice with Col1 alpha 2-CreER mice allowed for the generation of double transgenics which could be stimulated with tamoxifen to induce fibroblast-specific RelA deletion in adulthood. Conclusions: Based on our collective data, we conclude that this novel RelA(CKO/CKO) mouse allows for efficient deletion of RelA in a tissue-specific manner. This RelA(CKO/CKO) mouse will be an invaluable tool for deciphering the mechanistic roles of RelA in various cells and tissues during development and in disease.