Telomeres are nucleo-protein structures located at the end of chromosomes that protect them from degradation. Telomeres length is maintained by the activity of the telomerase complex. These structures are protected by a specialized protein complex named shelterin. In the absence of telomerase activity and/or protection telomeres are shortened after each round of DNA replication. When a critical size is reached, telomeres are recognized as damaged DNA by the cell p53-dependent DNA-repair system. Persistent activation of this pathway finally results in cell apoptosis or senescence.
Part of the book: Telomere