p53-dependent and independent apoptosis induced by ionizing radiation in murine bone marrow cells

摘要

APOPTOSIS or programmed cell death is a model of cell death, along with typical morphological and biochemical changes. The cell death, occurring during embryonic development, T and B cell maturation and endocrine-induced atrophy, is a physiological apoptosis which controls the amount of cells in the body. Apoptosis can also be induced by various factors, such as ionizing radiation and anti-tumour agents which damage DNA, and has been proposed to be a consequence of the induced expression of some tumour-related genes or increase of the proteins stability. p53 gene is an oncosuppressor, involved in the cellular proliferation controls through induced Gl/S block, In recent years it has been found that p53 gene plays an important role in the process of apoptosis triggered by DNA damage. In mouse thymocytes or epithelial stem cells of small intestinal tract, apoptosis induced by ionizing radiation is p53-dependent, including the increase of p53 gene expression or p53 protein stability. Owing to loss of p53 gene function, ionizing radiation failed to induce any apoptosis in the above tissues. In the present note, apoptosis induced by ionizing radiation is studied in the bone marrow cells from wild-type mice, p53 heterozygous and homozygous mutant mice.