ABSTRACT
The cellular senescence definition comes to the fact of cells irreversible proliferation disability. Besides the cell cycle arrest, senescent cells go through some morphological, biochemical, and functional changes which are the signs of cellular senescence. The senescent cells (including replicative senescence and stress-induced premature senescence) of all the tissues look alike. They are metabolically active and possess the set of characteristics in vitro and in vivo, which are known as biomarkers of aging and cellular senescence. Among biomarkers of cellular senescence telomere shortening is a rather elegant frequently used biomarker. Validity of telomere shortening as a marker for cellular senescence is based on theoretical and experimental data.
Subject(s)
Aging/metabolism , Cellular Senescence , Telomere Shortening , Telomere/metabolism , Age Factors , Aging/genetics , Aging/pathology , Animals , Cell Cycle Checkpoints , Cell Proliferation , Chromatin Assembly and Disassembly , Genetic Markers , Genetic Predisposition to Disease , Heterochromatin/metabolism , Histones/metabolism , Humans , Phenotype , Reproducibility of Results , Telomere/geneticsABSTRACT
We adduce proof that telomere shortening is the sole mechanism of aging. All apparent contradictions, particularly the absence of an inverse correlation between residual telomere length and donor age, are explained within the bounds of telomere theory. We explain in what way telomere shortening might be the cause of aging and lifespan restriction. We also show the inability of the oxidative theory to explain a number of indisputable (and easily explained by telomere theory) facts, such as malignant growth of tumor cells and why children begin aging not from the level reached by the cells of their parents at the moment of conception but from nothing. We postulate that if oxidative damage was entirely absent, telomeres would, nevertheless, shorten with each mitotic cycle because this is the mechanism of DNA replication. Aging would occur all the same, and it is the very thing we can observe under the effect of any antioxidants. If telomeres do not shorten, as is the case in transformed cells in which telomerase is working, aging will do stop and transformed cells will show no senescence. We also observe this in spite of the damaging effect of reactive oxygen species, which is even more intensive in transformed cells than in normal cells.
