Regulation of Human Telomerase: from Molecular Interactions to Population Genetics.

Human telomeres play critical roles in protecting chromosome ends and preserving genomic integrity. Telomerase, essential for maintaining telomere length and cellular replicative capacity, is only expressed in a small subset of human cells: stem and progenitor populations. Conversely, most somatic cells' telomeres shorten with each cell division; this shortening provides a potent tumor suppressor mechanism. Thus, telomerase regulation shapes not only cellular life span and differentiation, but also the regenerative capacity and long-term integrity of tissues. Here, we review the current understanding of telomere length control and telomerase regulation in humans, from molecular interactions at chromosome ends to the tissue-specific variation of telomere length dynamics, drawing insight from pluripotent and adult stem cell populations, as well as telomerase dysregulation in cancer and telomere biology disorders.