ABSTRACT
This chapter reviews the principal mechanisms involved in DNA homeostasis. DNA replication is a process in which all organisms must duplicate their genome with extreme accuracy before each cell division. DNA repair processes exist in prokaryotic and eukaryotic organisms, and many of the proteins involved are much conserved. All organisms have developed a complex network of DNA repair pathways: direct repair, base excision repair, nucleotide excision repair, mismatch repair, and recombination repair pathways. As telomere length shortens with age, gradual shortening of telomeres drives cells to senescence, apoptosis, oncogenic transformation of somatic cells, or increase the incidence of diseases. Some clinical data revealed that telomere length is shorter in patients with different types of cancer, including cancers of the head and neck, breast, bladder, prostate, lung, and kidney. Mutated proteins required for telomere structure, replication, repair and length maintenance have been linked to several debilitating human genetic disorders known as telomere biology disorders (TBDs).
