Expression of interferon regulatory factors (IRF-1 and IRF-2) during radiation-induced damage and regeneration of bone marrow by transplantation in mouse.

Interferon regulatory factors (IRF-1 and IRF-2) are transcription factors of IRF-family that regulate expression of genes for cytokines, chemokines and growth factors in mammalian cells. IRF-1 and IRF-2 play crucial roles in the differentiation of bone marrow cells for immune response. Bone marrow (BM) is the soft lymphoid organ that contains many types of stem cells and produces different types of cells of the blood and immune system. Genetic alterations and damage of the bone marrow cells can lead to different types of blood and immune system-related diseases including anemia and cancer. We have studied the expression of IRF-1 and IRF-2 during radiation-induced damage and regeneration of bone marrow cells after transplantation of freshly isolated bone marrow cells in the mouse. Cell cycle analysis, colony forming unit-fibroblast (CFU-F) assay and bone marrow histology showed that after radiation-induced damage, the bone marrow transplantation resulted in regeneration of the bone marrow up to 24-35% recovery. Real-time quantitative reverse transcription-polymerase chain reaction (Q-RT-PCR) for the mRNA expression showed that IRF-1 and IRF-2 were expressed at higher levels in the bone marrow cells of the irradiated (4.34× fold for IRF-1, and 3.87× fold for IRF-2) compared to control and transplanted (1.13× fold for IRF-1, and 1.12× fold IRF-2) mice and immuno-fluorescence analysis for the protein expression showed that IRF-1 and IRF-2 were expressed at higher levels in the bone marrow cells of the irradiated (2.12× fold for IRF-1 and 1.71× fold for IRF-2) compared to control and transplanted (1.73× fold for IRF-1 and 1.21× fold for IRF-2) mice. Thus, IRF-1 and IRF-2 are sensitive and responsive to radiation-induced damage in the bone marrow cells and may also be involved in the bone marrow regeneration process.