The December 5, 2016 issue of Nature Structural & Molecular Biology contains a study that deepens our understanding stem cell biology. This could lead to the advancement of stem cell-based treatments, particularly in relation to aging and regenerative medicines.
Telomeres, or telomeric structures, are found at the ends chromosomes. The same DNA sequence is repeated repeatedly. Telomeres are a region with repetitive nucleotide patterns at the ends of each chromosome. They protect the chromosome end from degradation or fusion. Telomeres are composed of TTAGGG nucleotides. The complementary DNA strand is AATCCC with an overhanging single-stranded sequence TTAGGG. The sequence TTAGGG occurs approximately 2,500 times per human. The average telomere size in humans decreases over time, from 11 kilobases when born to less than 4 kilobases as we age. Men experience a faster rate of decline than women.
The telomeres themselves are protected by a complex of shelterin proteins, as well as the RNA that telomeric DNA encodes (TERRA). Telomeres are protected both by a complex shelterin protein and by the RNA encoded by telomeric DNA (TERRA).
The chromosome can no longer replicate itself when the telomere is too short. This ‘critical’ length triggers the cell’s death by a process known as apoptosis.
Telomerase is an enzyme which adds the TTAGGG telomere to the ends of chromosomes. Telomerase can only be found in very small concentrations in somatic cells. These cells age because they do not use telomerase regularly.
Scientists say that the procedure, which uses a modified form of RNA, improves the researchers’ ability to produce large numbers of cells, either for drug development or study. The procedure allowed skin cells to multiply up to 40 times more than cells that were not treated. This research could lead to new treatments for diseases that are caused by shortened or damaged telomeres.
The modified RNA has been designed to reduce a cell’s response to treatment, and to allow the message encoded by TERT to remain in the cell for a little longer than if it were not modified. It dissipates within 48 hours. The newly lengthened Telomeres will begin to gradually shorten with each new cell division.
The aging process is caused by a combination of oxidative stress and glycation as well as chronological age, various genes, and telomere lengthening.
