Spontaneous γH2AX foci in human dermal fibroblasts in relation to proliferation activity and aging

Abstract

We assessed the effects of donor age on clonogenicity, proliferative potential, and spontaneous γH2AX foci in the proliferating (Ki67 +) and senescent (SA β-gal +) cultures of skin fibroblasts isolated from 34 donors of different age (23-82 years). Here, we demonstrated that neither the colony forming effectiveness of proliferating (Ki67+) fraction of the fibroblasts nor the average number of γH2AX foci of the same fraction does not depend on the age of the donor. The correlation between the number of γH2AX foci and the donor’s age was reliable in quiescent (Ki67-) cells. The average number of γH2AX foci in quiescent fibroblasts of donors older than 68 years was about two times higher than in the same cells of up to 30 years old donors. The number of γH2AX foci demonstrated a statistically significant positive correlation with the fraction of proliferating cells in fibroblast cultures. On average, proliferating cells have twice as many the γH2AX foci in comparison with the quiescent cells. Within a population of proliferating (Ki67+) cells, the degree of senescence correlated with a relative declining of constitutive γH2AX foci number, whereas in the population of quiescent (Ki67-) cells, it was proportional to augmenting the number of the γH2AX foci. Our data on a statistically significant (p=0.001) correlation between the age of the donor and the number of constitutive γH2AX foci in quiescent cells, could point out the ongoing DNA-damage response due in the maintenance of the senescent state of cells.

Exposing human primary dermal fibroblasts to particulate matter induces changes associated with skin aging

“…The analysis of the results for all three donors confirms that PM dose‐dependently increases the number of H2AX‐stained nuclear foci, as shown in Figure 7A. It is also important to note that histone H2AX is also phosphorylated during the S phase of the cell cycle in proliferating cells as the replicative forks collapse during DNA synthesis 26 . This explains the smaller number of phosphorylated H2AX nuclear foci present in the DMSO‐treated control cells.…”

“…It is also important to note that histone H2AX is also phosphorylated during the S phase of the cell cycle in proliferating cells as the replicative forks collapse during DNA synthesis. 26 This explains the smaller number of phosphorylated H2AX nuclear foci present in the DMSO-treated control cells. Due to the presence of phosphorylated H2AX in untreated controls it was important to analyze any differences in DSB induction between donors.…”

“…31 It is thought that increased cellular aging correlates with increased accumulation of DSBs and the impaired capacity to repair them. 26 The dose-dependent increase in the number of DSBs caused by PM demonstrates genotoxic potential which if sustained could lead to cellular senescence, and therefore, implicate air pollution in the premature aging of human skin.…”

Cellular aging beyond cellular senescence: Markers of senescence prior to cell cycle arrest in vitro and in vivo

“…What processes could be responsible for an increase in the frequency of DSBs throughout replicative aging? In cell culture conditions, one of the strongest drivers of DSBs is replication and especially, so‐called “replication stress” (Gelot et al, 2015; Lopez‐Contreras & Fernandez‐Capetillo, 2010; Zorin et al, 2019). Increase in cell cycle duration as well as the abovementioned changes in metabolism of primary cells is among the main inducers of replication stress (Magdalou et al, 2014).…”

Aging of Liver in Its Different Diseases

“…Cells reach their maximum while they still have the possibility of replication, that is, until they became senescent [ 40 ]. In research conducted on cell cultures, it has been proven that the factors that lead to the formation of double-strand breaks are stressors that affect cell replication and are important for the induction of reproductive senescence [ 43 , 44 ].…”