Biomarkers of aging
Biogerontologists have continued efforts to find and validate biomarkers of aging, but success thus far has been limited.
[7] Further studies of the hematological clock on the large datasets from South Korean, Canadian, and Eastern European populations demonstrated that biomarkers of aging may be population-specific and predictive of mortality.
In aging and dividing yeast MNase-seq (Micrococcal Nuclease sequencing) showed a loss of nucleosomes of ~50%.
In human primary fibroblasts, reduced synthesis of new histones was seen to be a consequence of shortened telomeres that activate the DNA damage response.
In C. elegans, the loss of any of the three Trithorax proteins that catalyze the trimethylation of H3K4 such as, WDR-5 and the methyltransferases SET-2 and ASH-2, lowers the levels of H3K4me3 and increases lifespan.
[13] In the rhesus macaque brain prefrontal cortex, H3K4me2 increases at promoters and enhancers during postnatal development and aging.
These changes may form an epigenetic memory of stresses and damages experienced by the organism as it develops and ages.
Utx-1 knockdowns showed an increase in lifespan[13] Changes in H3K27me3 levels also have affects on aging cells in Drosophila and humans.
Many studies have shown that there is a loss of DNA methylation during ageing in many species such as, rats, mice, cows, hamsters, and humans.
[15] Hypomethylation of DNA can lower genomic stability, induce the reactivation of transposable elements, and cause the loss of imprinting, all of which can contribute to cancer progression and pathogenesis.
[16] Recently, Hashimoto and coworkers profiled thousands of circulating immune cells from supercentenarians at single-cell resolution.
The conversion of helper CD4 T-cells to a cytotoxic variety might be an adaptation to the late stage of aging aiding in the fighting infections and potentially enhancing tumor surveillance.
Thus after establishing a biomarker of aging, humans would be able to dive into research on extending life spans and finding timelines for the arise of potential genetic diseases.
