Telomeres are the end portions of chromosomes, among others. protecting them from inappropriate DNA repair mechanisms. Telomere length is regulated by the action of many different proteins: TRF1, TRF2, TIN2, TANK1, TANK2. TRF1 and TRF2 proteins are involved in the formation of specific structures called t-loops that protect telomeres from fusions "end to end". TANK1 and TANK2, belong to a class of proteins PARP. These proteins regulate the function of telomeres by poly-ADP-ribosylation. Because of systematic loss of telomeric repeats during cell division, and telomerase associated proteins are essential for maintaining genome stability. Interactions between all these factors are very complex and still poorly understood.