Causes and consequences of the DNA damage response.

A prerequisite for maintaining genome stability in all cell types is the accurate repair and efficient signaling of DNA double strand breaks (DSBs). It is believed that DSBs are initially detected by damage sensors that trigger the activation of transducing kinases. These transducers amplify the damage signal, which is then relayed to effector proteins, which regulate the progression of the cell cycle, DNA repair and apoptosis. Errors in the execution of the repair and/or signaling of DSBs can give rise to multi-systemic disorders characterized by tissue degeneration, infertility, immune system dysfunction, age-related pathologies and cancer. This special Spotlight issue of Cell Cycle highlights recent advances in our understanding of the biology and significance of the DNA damage response. A range of issues are addressed including mechanistic ones: What is the aberrant DNA structure that triggers the activation of the checkpoint? How does chromatin structure influence the recruitment of repair and checkpoint proteins? How does chromosomal instability contribute to the evolution of cancer? In addition, questions related to the physiology of the DNA damage response in normal and abnormal cells is explored: What is the in vivo consequence of altering specific amino acids in a DNA damage sensor? Does DNA damage accumulation in stem cells cause aging? How is neurodegeneration linked to deficiencies in specific DNA repair pathways? And finally, what is the biological basis for selection of aberrant DNA damage responses in cancer cells?