c-MAF deletion in adult C57BL/6J mice induces cataract formation and abnormal differentiation of lens fiber cells

The transcription factor c-MAF is a member of the large MAF family, members of which possess transactivation and bZIP domains. c-MAF plays an important role in lens formation, T-lymphocyte differentiation, hypertrophic chondrocyte differentiation, and kidney development in mouse embryos. However, because homozygous deletion of c-Maf in C57BL/6J mice causes embryonic lethality, the functions of c-MAF in adult mice remain largely uninvestigated. To address this issue, we generated c-Maf floxed (c-Maf(fl/fl)) C57BL/6J mice and established tamoxifen-inducible c-Maf knockout mice (c-Maf(fl/fl); CAG-Cre-ER(TM) mice, c-Maf(ΔTAM)). After tamoxifen injection, adult c-Maf(ΔTAM) mice showed successful deletion of c-Maf protein and developed severe cataracts; cataracts are also seen in human patients who have mutations in the c-MAF DNA binding domain. Furthermore, adult c-Maf(ΔTAM) mice exhibited abnormal lens structure and impaired differentiation of lens fiber cells. In summary, we established c-Maf(fl/fl) and c-Maf(ΔTAM) C57BL/6J mice, which can be useful animal models for the investigation of c-MAF function in various developmental stages and can also be used as a disease model for cataracts.