Closed chromatin loops at the ends of chromosomes

T Nikitina, CL Woodcock - The Journal of cell biology, 2004 - rupress.org
T Nikitina, CL Woodcock
The Journal of cell biology, 2004rupress.org
The termini of eukaryotic chromosomes contain specialized protective structures, the
telomeres, composed of TTAGGG repeats and associated proteins which, together with
telomerase, control telomere length. Telomere shortening is associated with senescence
and inappropriate telomerase activity may lead to cancer. Little is known about the
chromatin context of telomeres, because, in most cells, telomere chromatin is tightly
anchored within the nucleus. We now report the successful release of telomere chromatin …
The termini of eukaryotic chromosomes contain specialized protective structures, the telomeres, composed of TTAGGG repeats and associated proteins which, together with telomerase, control telomere length. Telomere shortening is associated with senescence and inappropriate telomerase activity may lead to cancer. Little is known about the chromatin context of telomeres, because, in most cells, telomere chromatin is tightly anchored within the nucleus. We now report the successful release of telomere chromatin from chicken erythrocyte and mouse lymphocyte nuclei, both of which have a reduced karyoskeleton. Electron microscopy reveals telomere chromatin fibers in the form of closed terminal loops, which correspond to the “t-loop” structures adopted by telomere DNA. The ability to recognize isolated telomeres in their native chromatin conformation opens the way for detailed structural and compositional studies.
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