Sizing the ends: normal length of human telomeres.
The ends of human chromosomes are constituted of telomeres, a nucleoprotein complex. They are mainly formed by the entanglement of repeat DNA and telomeric and non-telomeric proteins. Telomeric sequences are lost in each cell division and this loss happens in vitro as well as in vivo. The diminution of telomere length over the cell cycle has led to the consideration of telomeres as a 'mitotic clock'. Telomere lengths are heterogeneous because they differ among tissues, cells, and chromosome arms. Cell proliferation capacity, cellular environment, and epigenetic factors are some elements that affect this telomere heterogeneity. Also, genetic and environmental factors modulate the difference in telomere lengths between individuals. Telomere length is regulated by telomere structure, telomerase, the enzyme that elongates the 3'-end of telomeres, and alternative lengthening of telomeres (ALT) used exclusively in immortalized and cancer cells. The understanding of telomere length dynamic in the normal population is essential to develop a deeper insight into the role of telomere function in pathological settings.
Samassekou
Oumar
O
Division of Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, QC J1H 5N4, Canada.
Gadji
Macoura
M
Drouin
Régen
R
Yan
Ju
J
D002453:Cell Cycle / Q000235:genetics; D002455:Cell Division; D002877:Chromosomes, Human / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D006801:Humans; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000737:chemistry / Q000378:metabolism*
D004247:DNA; D019098:Telomerase