[The role of the DNA damage response in apoptosis and cell senescence].

The genetic material is constantly subjected to DNA damage which is caused by physiological processes occuring in the cell and is exposed to exogenous DNA damaging agents. Eucariotic cells have developed a system called the DNA damage response (DDR), which is responsible for maintaining genomic inegrity. DNA damage can lead to senescence, DNA repair as well as to cell death. The key protein in the DDR pathway is p53. This protein undergoes numerous posttranslational modifications and can be involved in the activation of many genes and proteins leading to survival or cell death. In cell senescence the p53 protein leads to the induction of p21, which causes cell cycle arrest. In apoptosis p53 participates in the activation of caspases, which are responsible for the degradation of many proteins.